Abstract:
A display apparatus for a vehicle is capable to change a display condition to display information for driving in a field of a front view of a driver. The display apparatus for a vehicle, installed in a dashboard of the vehicle for displaying a virtual image of the information in a field of front view of a driver by projecting the information displayed on an LCD illuminated by a lighting device on a member of projection disposed at an outside of the dashboard, includes display-size change means  4  for changing a display size of the LCD  3  and illuminating-area change means  20   a  for changing illuminating area in accordance with the changed display size interlockingly with said display-size change means.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a display apparatus for a vehicle, installed in a dashboard of the vehicle and displays a virtual image of information of the vehicle within a field of front view of a vehicle driver by projecting the information of the vehicle displayed on an image plane of an LCD illuminated by a lighting device on a windshield or a combiner disposed at an outside of the dashboard. 
   2. Description of the Related Art 
   This kind of the display apparatus for the vehicle, called a head up display (HUD), is applied to display auxiliary information for driving in a filed of a front view, as disclosed in J.U.M Application Laid-open H4-54020, and has a feature to recognize auxiliary information without moving eye point during driving. 
     FIG. 28  shows an outline drawing of a usual display apparatus for the vehicle as mentioned above. A virtual image  10  of a speed meter is displayed on a windshield  2  located above an instrument panel  2   a  of a vehicle  1 . 
     FIG. 29  shows a structure for displaying the virtual image  10 . The instrument panel  2   a  is provided inside thereof with a convex lens  5 , LCD (Liquid Crystal Display)  3 , a light source  6  and an LCD drive circuit  4 . The LCD  3  is disposed on a focal point of the convex lens  5 . The light source  6  is disposed behind a semi-transparent mirror  12  at opposite side against the convex lens  5  regarding the LCD  3 . 
   The LCD  3  includes a display plate  3   a , a negative-positive image switching plate  3   b  and a polarizing plate  3   c . The LCD  3  is connected to the LCD drive circuit  4  connected to a car speed sensor  13 . 
   The light source  6  has a high brightness lamp  6   a  and a low brightness lamp  6   b  those are separated by the semi-transparent mirror  12  in a lamp case  14 . Each light of the lamps  6   a ,  6   b  enters respectively from a bottom side of the LCD  3  into the convex lens  5  by the semi-transparent mirror  12 . A negative-positive image select switch  15  is connected between the negative-positive image switching plate  3   b  and the LCD drive circuit  4 . A lamp select switch  16  is connected between the high brightness lamp  6   a  and the low brightness lamp  6   b . The both select switches  15 ,  16  are switched interlockingly with a side lamp switch  17  of the vehicle. 
   According to above structure, a display image Q is generated on the LCD  3  by converting a signal of the car speed sensor  13  to an LCD drive signal in the LCD drive circuit  4 . A polarizing direction of the polarizing plate  3   c  attached on the bottom side of the LCD is selected so as to show the display image Q by a negative image in the field of the front view as  FIG. 30A . In the daytime, the high bright lamp  6   a  is turned ON at the same time when the LCD displays an image. Light of the high brightness lamp reflected in the lamp case  14  is reflected at the semi-transparent mirror  12  to illuminate the display image Q of the LCD  3  and goes through the convex lens  5 . The light is reflected on the windshield  2  so as to display the negative image (virtual image  10 ) in the front view as shown in  FIG. 30A . 
   In the nighttime, the side lamp  17  is turned ON and the light source  6  is selected to the low brightness lamp  6   b  by the lamp select switch  16 . Simultaneously, the negative-positive image select switch  15  is turned ON and the virtual image  10  in the front view is switched to the positive image as shown in  FIG. 30B . This selection of images is done by driver&#39;s judgement. 
   Objects to be Solved 
   The head up display is required to select display only for nighttime other than common display for daytime and nighttime. The display only for nighttime may be an image by a night vision camera or an image processed the image by the night vision camera. When such image is displayed, a display condition, such as a display size or display brightness, may be different from the common display (for daytime) preferably to be seen easily by the driver. 
   In the above-mentioned usual display apparatus for a vehicle, the display size of the virtual image in the front view is the same in the daytime and the nighttime, and cannot change the display size as occasion demands. 
   To overcome the above drawback of a usual display apparatus for a vehicle, one object of this invention is to provide a display apparatus for a vehicle which can change a display condition to display information for driving in a field of a front view of a vehicle driver. 
   SUMMARY OF THE INVENTION 
   How to Attain the Object 
   In order to attain the objects, a display apparatus for a vehicle according to this invention, which is installed in a dashboard of the vehicle and displays a virtual image of information of the vehicle within a field of front view of a vehicle driver by projecting the information of the vehicle displayed on an image plane of an LCD illuminated by a lighting device on a member of projection disposed at an outside of the dashboard, includes display-size change means for changing a display size on the image plane of the LCD, and illuminating-area change means for changing an illuminating area in accordance with the changed display size interlockingly with said display-size change means. 
   As mentioned above, the display apparatus for the vehicle is installed in the dashboard of the vehicle and displays the virtual image of information of the vehicle in the front view of the vehicle by projecting the information of the vehicle displayed on the image plane of the LCD illuminated by the lighting device on a member of projection disposed at an outside of the dashboard and includes display-size change means for changing the display size on the image plane of the LCD, and illuminating-area change means for changing an illuminating area in accordance with the changed display size interlockingly with the display-size change means. Therefore, in normal display condition including daytime a small size image can be displayed in high resolution, and in display condition for nighttime a large size image can be displayed in low brightness. Thus, display conditions of information for driving in the field of a front view can be selected. 
   The display apparatus according to this invention is more specified by that the display-size change means includes a drive circuit for driving the LCD and a display-size change switch connected to the drive circuit for outputting a switching signal for changing the display size of the LCD in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the display-size change means includes the drive circuit for driving the LCD and the display-size change switch connected to the drive circuit for outputting the switching signal for changing the display size of the LCD so that the display size of the LCD can be changed to a small display size for normal display condition including daytime or to a large display size for nighttime. 
   The display apparatus according to this invention is more specified by that the illuminating-area change means includes an illuminating-area change switch for outputting a switching signal for changing the illuminating area of the lighting device interlockingly with said display-size change switch in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the illuminating-area change means includes an illuminating-area change switch for outputting a switching signal for changing the illuminating area of the lighting device interlockingly with said display-size change switch so that the illuminating area of the LCD can be changed in accordance with the display size. 
   The display apparatus according to this invention is more specified by that the display-size change switch and the illuminating-area change switch interlock a side-lamp switch of the vehicle, and when the side-lamp switch is turned ON, the display-size change means changes the display size of the LCD larger than before, and the illuminating-area change means changes the illuminating area in accordance with the changed display size larger than before in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the display-size change switch and the illuminating-area change switch interlock a side-lamp switch of the vehicle, and when the side-lamp switch is turned ON, the display-size change means changes the display size of the LCD larger than before, and the illuminating-area change means changes the illuminating area in accordance with the changed display size larger than before so that, by turning the side lamp ON in the nighttime, the large image size for nighttime can be displayed automatically in low brightness. 
   The display apparatus according to this invention is more specified by that the lighting device includes a back light having a first light source, a reflector for reflecting light from the first light source and a light-guide plate disposed in parallel to the LCD for radiating plane light to the LCD, the plane light being converted from reflected light by the reflector to be entered into the light-guide plate from an edge thereof, and a second light source to be turned ON when the first light source is turned OFF and apply light onto one surface of the light-guide plate to be reflected on the one surface for radiating the reflected light to the LCD, and the illuminating-area change means has a light-guide plate angle change mechanism for changing an angle of the light-guide plate against the LCD to other than in parallel when the second light source is turned ON in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lighting device includes the back light and the second light source, the back light having the first light source, the reflector for reflecting light from the first light source and the light-guide plate disposed in parallel to the LCD for radiating plane light to the LCD, the plane light being converted from reflected light by the reflector entered into the edge of the light-guide plate, second light source to be turned ON when the first light source is turned OFF and apply light onto one surface of the light-guide plate to be reflected on the one surface for radiating the reflected light to the LCD, and the illuminating-area change means has the light-guide plate angle change mechanism for changing an angle of the light-guide plate against the LCD to other than in parallel when the second light source is turned ON, so that the illuminating area of the LCD can be changed by using the light-guide plate of the back light. 
   The display apparatus according to this invention is more specified by that the second light source emits diverging light in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the second light source emits diverging light so that the reflector can be miniaturized. 
   The display apparatus according to this invention is more specified by that the light-guide plate angle change mechanism changes the angle of a part of the light-guide plate or the whole thereof against the LCD to other than in parallel in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the light-guide plate angle change mechanism changes the angle of a part of the light-guide plate or the whole thereof against the LCD to other than in parallel so that the illuminating area can be changed by using a part of the light-guide plate or the whole thereof. 
   The display apparatus according to this invention is more specified by that the light-guide plate angle change mechanism is provided with a plurality of stays and support walls disposed at the both sides of the light-guide plate, one end of the stay being fixed on a predetermined position of the light-guide plate and the other end of the stay being provided with a support shaft, the guide wall having guide grooves in which support shafts of the plurality of stays are respectively inserted movably for supporting the light-guide plate rotatably in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the light-guide plate angle change mechanism is provided with the plurality of stays and support walls disposed at the both sides of the light-guide plate, one end of the stay being fixed on the predetermined position of the light-guide plate and the other end of the stay being provided with the support shaft, the guide wall having guide grooves in which support shafts of the plurality of stays are respectively inserted movably for supporting the light-guide plate rotatably so that the light-guide plate angle can be changed smoothly. 
   The display apparatus according to this invention is more specified by that the light-guide plate is provided on a rear surface thereof with a reflective film in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the light-guide plate is provided on a rear surface thereof with a reflective film so that the rear surface of the light-guide plate can be used for a reflective surface. 
   The display apparatus according to this invention is more specified by that the light-guide plate is formed at a partial surface thereof into convex or concave shape in the display mentioned above. 
   In the display apparatus for a vehicle mentioned above, the light-guide plate is formed at a partial surface thereof into convex or concave shape so that changing the illuminating area can be enhanced. 
   The display apparatus according to this invention is more specified by that the lighting device includes a light source, a first reflector for reflecting light from the light source and a second reflector having a different size from that of the first reflector for reflecting the light from the light source, and the illuminating-area change means has a reflector change mechanism for changing reflectors to illuminate the LCD at different illuminating area with the reflected light by the first or second reflector which are disposed changeably against the light source in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lighting device includes the light source, the first reflector for reflecting the light from the light source and the second reflector having a different size from that of the first reflector for reflecting the light from the light source, and the illuminating-area change means has the reflector change mechanism for changing reflectors to illuminate the LCD at different illuminating area with the reflected light by the first or second reflector which are disposed changeably against the light source so that the illuminating area of the LCD can be changed by using one light source. 
   The display apparatus according to this invention is more specified by that the reflector change mechanism includes a rack fixed on the first or second reflector, a pinion engaging with the rack and driving means for rotating the pinion in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the reflector change mechanism includes the rack fixed on the first or second reflector, the pinion engaging with the rack and driving means for rotating the pinion so that the first or second reflector can be changed securely. 
   The display apparatus according to this invention is more specified by that the lighting device includes a first lighting device and a second lighting device, the first lighting device having a first light source and a first reflector for reflecting light from the first light source toward the LCD for illuminating a part of the LCD, the second lighting device having a second light source and a second reflector for reflecting light from the second light source toward the LCD for illuminating a part of the LCD, and the illuminating-area change means has a radiating direction change mechanism for changing radiating directions of the first and second light sources to separate or superimpose respective illuminating areas on the LCD of the first and second lighting devices in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lighting device includes the first lighting device and the second lighting device, the first lighting device having the first light source and the first reflector for reflecting the light from the first light source toward the LCD for illuminating the part of the LCD, the second lighting device having the second light source and the second reflector for reflecting the light from the second light source toward the LCD for illuminating the part of the LCD, and the illuminating-area change means has a radiating direction change mechanism for changing radiating directions of the first and second light sources to separate or superimpose respective illuminating areas on the LCD of the first and second lighting devices so that the illuminating area of the LCD can be changed by separating or superimposing the lights of two lighting devices. 
   The display apparatus according to this invention is more specified by that the radiating direction change mechanism includes a first gear mounted on the first lighting device, a second gear mounted on the second lighting device and having a same number of teeth as the first gear, a third gear engaging with the first gear, a fourth gear engaging with the second gear and the third gear and having a same number of teeth as the third gear, and driving means for rotating the third or fourth gear in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the radiating direction change mechanism includes the first gear mounted on the first lighting device, the second gear mounted on the second lighting device and having the same number of teeth as the first gear, the third gear engaging with the first gear, the fourth gear engaging with the second gear and the third gear and having the same number of teeth as the third gear, and driving means for rotating the third or fourth gear so that the radiating directions of two lighting devices can be changed securely so as to separate or superimpose illuminating areas of the LCD by two lighting devices. 
   The display apparatus according to this invention is more specified by that the lighting device includes a light source and a concave reflector for reflecting light from the light source to the LCD, and the illuminating-area change means has a position change mechanism for changing a relative position between the light source and the concave reflector so as to position the light source on a focal point, or in front or in back of the focal point of the concave reflector in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lighting device includes the light source and the concave reflector for reflecting the light from the light source to the LCD, and the illuminating-area change means has the position change mechanism for changing the relative position between the light source and the concave reflector to position the light source on the focal point, or in front or in back of the focal point of the concave reflector so that the illuminating area of the LCD can be changed by using one light source. 
   The display apparatus according to this invention is more specified by that a lens is disposed between the light source and the LCD in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lens is disposed between the light source and the LCD so that changing the illuminating area can be enhanced. 
   The display apparatus according to this invention is more specified by that the lighting device includes a light source, convex reflector for reflecting light from the light source to the LCD and a concave reflector for reflecting the light from the light source to the LCD, and the illuminating-area change means has a reflector change mechanism for changing reflectors to illuminate the LCD at different illuminating area with the reflected light by the convex or concave reflector which are disposed changeably against the light source in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the lighting device includes the light source, convex reflector for reflecting the light from the light source to the LCD and the concave reflector for reflecting the light from the light source to the LCD, and the illuminating-area change means has the reflector change mechanism for changing reflectors to illuminate the LCD at different illuminating area with the reflected light by the convex or concave reflector which are disposed changeably against the light source so that the illuminating area of the LCD can be changed by using one light source. 
   The display apparatus according to this invention is more specified by that the reflector change mechanism includes a stay and a motor, and the convex reflector is fixed on one end of the stay and the concave reflector is fixed on the other end of the stay, and a rotating shaft of the motor is fixed on a middle portion of the stay and the motor rotates the convex reflector or the concave reflector by rotating the stay for changing reflectors between the light source and the LCD in the display apparatus mentioned above. 
   In the display apparatus for a vehicle mentioned above, the reflector change mechanism includes the stay and the motor, and the convex reflector is fixed on one end of the stay and the concave reflector is fixed on the other end of the stay, and the rotating shaft of the motor is fixed on the middle portion of the stay and the motor rotates the convex reflector or the concave reflector by rotating the stay for changing reflectors between the light source and the LCD so that the convex reflector or the concave reflector can be changed securely. 
   The above and other objects and features of this invention will become more apparent from the following description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of a display apparatus for a vehicle according to this invention; 
       FIG. 2  is an outline drawing to explain an example of display by the display apparatus for the vehicle in  FIG. 1 ; 
       FIG. 3A  is a drawing, showing an example of displaying in the daytime; 
       FIG. 3B  is a drawing, showing an example of displaying in the nighttime; 
       FIG. 4  is a perspective view, showing a first embodiment of the lighting device of the display apparatus for a vehicle in  FIG. 1 ; 
       FIG. 5  is a perspective view of the lighting device removed a part from the lighting device in  FIG. 4 ; 
       FIG. 6  is a drawing for explaining operation of the lighting device in  FIG. 4 ; 
       FIG. 7  is a drawing, showing the other example of a light source of the lighting device in  FIG. 4 ; 
       FIGS. 8A ,  8 B are drawings, showing the other examples of the lighting device in  FIG. 4 ; 
       FIG. 9  is a perspective view, showing a further modified example of the lighting device in  FIG. 4 ; 
       FIG. 10  is a perspective view of the lighting device removed a part from the lighting device in  FIG. 9 ; 
       FIG. 11  is a drawing for explaining operation of the lighting device in  FIG. 9 ; 
       FIG. 12  is a drawing, showing the other example of a light source of the lighting device in  FIG. 9 ; 
       FIG. 13  is a drawing, showing the other example of a light-guide plate of the lighting device in  FIG. 9 ; 
       FIG. 14  is a drawing, showing a second embodiment of the lighting device of the display apparatus for a vehicle in  FIG. 1 ; 
       FIG. 15  is a drawing, showing relative position of the light source and the reflector in  FIG. 14 ; 
       FIGS. 16A ,  16 B are perspective views of the lighting device in  FIG. 14 ; 
       FIGS. 17A ,  17 B are drawings for explaining operation of the lighting device in  FIG. 14 ; 
       FIGS. 18A ,  18 B are drawings, showing a third embodiment of the lighting device of the display apparatus for a vehicle in  FIG. 1 ; 
       FIG. 19  is a drawing, showing relative position of the light source and the reflector in  FIG. 18A  or  18 B; 
       FIGS. 20A ,  20 B are perspective views of the lighting device in  FIGS. 18A and 18B ; 
       FIGS. 21A ,  21 B,  21 C are drawings, showing a fourth embodiment of the lighting device of the display apparatus for a vehicle in  FIG. 1 ; 
       FIGS. 22A ,  22 B are perspective views of the lighting device in  FIGS. 21A ,  21 B; 
       FIGS. 23A ,  23 B are drawings, showing the other examples of the lighting device in  FIGS. 21A ,  21 B; 
       FIG. 24  is a schematic perspective view of the lighting device in  FIG. 23A ; 
       FIG. 25  is a schematic perspective view for explaining operation of mounting and dismounting a lens of the lighting device in  FIG. 24 ; 
       FIGS. 26A ,  26 B are drawings, showing a fifth embodiment of the lighting device of the display apparatus for a vehicle in  FIG. 1 ; 
       FIGS. 27A ,  27 B are schematic perspective views of the lighting devices in  FIGS. 26A ,  26 B; 
       FIG. 28  is an outline drawing of a usual display apparatus for the vehicle; 
       FIG. 29  is a whole diagram of a usual display apparatus for a vehicle; and 
       FIGS. 30A ,  30 B are drawings, showing examples of display by the usual display apparatus for the vehicle. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An embodiment of a display apparatus for a vehicle according to this invention will be described with reference to drawings.  FIG. 1  is a schematic diagram of the embodiment of the display apparatus for the vehicle according to this invention. In  FIG. 1 , the display apparatus for the vehicle installed in the dashboard (not shown) includes a convex lens  5 , an LCD (Liquid Crystal Display)  3 , an LCD drive circuit  4  and an illuminating device  20 . The LCD  3  is positioned on a focal point of the convex lens  5 . The illuminating device  20  is disposed at an opposite side against the convex lens  5  regarding the LCD  3 . 
   The LCD  3  includes a display plate  3   a  and a light control plate  3   d  for guiding effectively light from the later-described lighting device  20  and performing as a light diffusion plate to prevent non-uniformity of brightness. The LCD  3  is connected to the LCD drive circuit  4  for performing a part of a display-size change means. The LCD drive circuit is connected to a display-size change switch  4   a  for performing a part of the display-size change means. 
   The lighting device  20  for lighting the LCD  3  from behind through the light control plate  3   d  interlocks the display-size change switch  4   a  and is connected to a illuminating-area change switch  20   a  for outputting a illuminating-area change signal to the lighting device  20 . 
   According to the above-mentioned structure, in the daytime, the display-size change switch  4   a  and the illuminating-area change switch  20   a  are set OFF, and the LCD drive circuit drives the LCD  3  to display in normal display size, and the lighting device  20  applies high-brightness light through the light control plate  3   d  in the illuminating area for normal display size in accordance with the normal display size of the LCD  3 . 
   In the nighttime, when the display-size change switch  4   a  and the illuminating-area change switch  20   a  are turned ON, the display-size change switch  4   a  outputs a display-size change signal to the LCD drive circuit  4  so that the LCD drive circuit  4  drives the LCD  3  to display in a display size for night larger than the normal display size. The illuminating-area change switch  20   a  outputs an illuminating-area change signal to the lighting device  20  so that the lighting device  20  applies low-brightness light through the light control plate  3   d  in the illuminating area for night in accordance with the display size for night of the LCD  3 . 
     FIG. 2  is an outline drawing to explain an example of display by the display apparatus for the vehicle in  FIG. 1 . A normal display  3 A having a small display size or a display for night  3 B having larger display size than that of the normal display  3 A is displayed as a virtual image  10  correspondingly to switching display size of the LCD  3  on the windshield  2  above the dashboard of the vehicle  1 . 
   The normal display  3 A is, for example shown in  FIG. 3A , display for car speed and is required high brightness to be recognized the display at background brightness of the daylight (sunlight or reflected light of sunlight on a road or a snow ground). 
   The display for night  3 B may be displayed in the same display size as the normal display size shown in  FIG. 3A  by darkening (i.e. reducing the brightness lower than that of normal display) or can be displayed in larger display size than that of the normal display  3 A in case of displaying a rear monitor image of an infrared camera as shown in  FIG. 3B . 
   The lighting device  20  is physically structured as following. 
     FIGS. 4–13  show a first embodiment of the lighting device  20 . In  FIG. 4 , the lighting device  20  includes a back-light  201  having a rod-like light source  201   a  (white light source such as a cold-cathode tube or a xenon lamp) for applying low brightness light as a first light source, a reflector  201   b  for reflecting light from the rod-like light source  201   a  and a light-guide plate  201   c  disposed in parallel to the LCD  3  for radiating plane light, converted from reflected light by the reflector entered into an edge of the light-guide plate, toward the LCD  3 , and a lamp  202  applying high-brightness parallel light as a second light source for radiating reflected light on one surface of the light-guide plate  201   c  toward the LCD  3 . The lamp  202  is a light source for normal display and the back-light  201  is a light source mainly for a display at night. A part  201   c   1  of the light-guide plate  201   c  is also used as a reflecting plate for reflecting parallel light from the lamp  202  at normal displaying. 
   Angle of the part  201   c   1  of the light-guide plate  201   c  can be changed to an angle other than in parallel to the LCD  3  by a light-guide plate angle change mechanism as a part of the illuminating-area change means having a plurality of stays  203  and support walls  204  disposed at the both sides of the light-guide plate  201   c , one end of the stay  203  being fixed on a predetermined position of the part  201   c   1  of the light-guide plate  201   c  and the other end of the stay  203  being provided with a support shaft  203   a , the guide wall  204  having guide grooves  204   a  in which support shafts  203   a  of the plurality of stays  203  are respectively inserted movably for supporting the part  201   c   1  of the light-guide plate  201   c  rotatably. 
     FIG. 5  is a drawing by removing the support walls  204  in  FIG. 4  to see locations of the stays  203  easily. 
   According to the above structure, in the daytime, the rod-like light source  201   a  is turned OFF and the lamp  202  is turned ON, and the part  201   c   1  of the light-guide plate  201   c  is rotated by the light-guide plate angle change mechanism operated on turning the illuminating-area change switch  20   a  OFF to a predetermined angle other than in parallel to the LCD  3 , as shown in  FIG. 6 . The high-brightness parallel light of the lamp  202  is reflected on top surface and rear surface of the rotated part  201   c   1  of the light-guide plate  201   c  to be used for a reflecting plate, and radiated through the light control plate  3   d  in illuminating area in accordance with the normal display size on the LCD  3  set by turning the display-size change switch  4   a  OFF. 
   In the nighttime, the rod-like light source  201   a  is turned ON and the lamp  202  is turned OFF, and the part  201   c   1  of the light-guide plate  201   c  is rotated toward in parallel to the LCD  3  by the light-guide plate angle change mechanism operated when turning the illuminating-area change switch  20   a  ON, as shown in  FIG. 4 . The low-brightness light of the rod-like light source  201   a  is converted to plane light through the whole of the light-guide plate  201   c , and radiated through the light control plate  3   d  in large illuminating area in accordance with the display size for night on the LCD  3  set by turning the display-size change switch  4   a  ON. 
   Light of the lamp  202  can be diffuse light, not parallel light as mentioned above, accordingly to a reflector (not shown) for miniaturizing the reflector, as shown in  FIG. 7 . 
   If normal display size of the LCD  3  is smaller than the display size shown in  FIG. 6 , rotating area for reflecting plate of the light-guide plate  201   c  may be a part  201   c   2  ( FIGS. 4 ,  5 ) smaller than the part  201   c   1  mentioned above, as shown in  FIGS. 8A ,  8 B. In this case, the lamp  202  and the reflector can be miniaturized more and the lamp  202  can be disposed below the light-guide plate  201   c  as shown in  FIG. 8A  or above the light-guide plate  201   c  as shown in  FIG. 8B . 
     FIG. 9  is a more modified embodiment of the lighting device  20  in  FIG. 4 . Rear surface of the light-guide plate  201   c  (opposite surface to a top surface facing to the LCD  3 ) is coated with reflecting film and the part  201   c  of the light-guide plate  201   c  is supported by the light-guide plate angle change mechanism including a plurality of stays  203  and support walls  204  having guide grooves  204   a  those are modified to rotate counter-clockwise from a position in parallel to the LCD  3 . 
     FIG. 10  is a drawing by removing the support walls  204  in  FIG. 9  to see locations of the stays  203  easily. 
   According to the above structure, in the daytime, the rod-like light source  201   a  is turned OFF and the lamp  202  is turned ON, and the part  201   c   1  of the light-guide plate  201   c  is rotated counter-clockwise by the light-guide plate angle change mechanism operated on turning the illuminating-area change switch  20   a  OFF to a predetermined angle other than in parallel to the LCD  3 , as shown in  FIG. 11 . The high-brightness parallel light of the lamp  202  is reflected on the reflecting film on the rear surface of the rotated part  201   c   1  of the light-guide plate  201   c , and radiated through the light control plate  3   d  in illuminating area in accordance with the normal display size on the LCD  3  set by turning the display-size change switch  4   a  OFF. 
   In the nighttime, the rod-like light source  201   a  is turned ON and the lamp  202  is turned OFF, and the part  201   c   1  of the light-guide plate  201   c  is rotated by the light-guide plate angle change mechanism operated on turning the illuminating-area change switch  20   a  ON to make the whole of the light-guide plate  201   c  in parallel to the LCD  3 , as shown in  FIG. 9 . The low-brightness light of the rod-like light source  201   a  is converted to plane light through the whole of the light-guide plate  201   c , and radiated through the light control plate  3   d  in large illuminating area in accordance with the display size for night on the LCD  3  set by turning the display-size change switch  4   a  ON. 
   Light of the lamp  202  can be diffuse light, not parallel light as mentioned above, accordingly to a reflector (not shown) for miniaturizing the reflector, as shown in  FIG. 12 . 
   By miniaturizing the lamp  202  for radiating parallel light and forming rear surface of the light-guide plate into convex surface  201   c   3  as shown in  FIG. 13 , diffuse light converted from the parallel light of the lamp  202  on the convex surface  201   c   3  may be radiated to the LCD  3 . 
     FIGS. 14–17  show examples according to a second embodiment of the lighting device  20 . In  FIG. 14 , the lighting device  20  includes a lamp  211  as a light source, a first semicylindrical-concave reflector  212  disposed with a predetermined distance from the lamp  211  for reflecting light from the lamp  211  and a second semicylindrical-concave reflector  213  larger than the first reflector  212 , disposed with a more distance than that of the first reflector  212  from the lamp  211 , for reflecting light from the lamp  211 . 
   The light of the lamp  211  can be reflected on the first reflector  212  so as to be converted to parallel light by disposing the lamp  211  at a focal point F (or in the vicinity of the focal point F) of the first reflector  212  and the second reflector  213  (not shown in  FIG. 15 ) as shown in  FIG. 15 . If higher brightness is required, the lamp  211  may be disposed at a far side of the focal point F from the first reflector  212 , and if wider illuminating area is required, the lamp  211  may be disposed at a near side of the focal point F to the first reflector  212 . 
   The first reflector  212  is mounted on a reflector change mechanism as shown in  FIG. 16A . The reflector change mechanism includes a rack  214  fixed on the first reflector  212 , a pinion  215  engaging with the rack  214  and driving means having a motor  216  and a gearing portion  217  for rotating the pinion  215 . 
   The reflector change mechanism moves the first reflector  212  in a position to reflect the light from the lamp  211  as shown in  FIG. 16A , and moves the first reflector  212  from the position to reflect the light from the lamp  211  by the gearing portion  217 , the pinion  215  and the rack  214  driven by the motor  216  so as to reflect the light from the lamp  211  on the second reflector  213  instead of the first reflector  212  as shown in  FIG. 16B . 
   According to the above structure, in the daytime, the first reflector  212  is set in the position to reflect the light from the lamp  211  by the reflector change mechanism operated by turning the illuminating-area change switch  20   a  OFF as shown in  FIG. 17A . The high-brightness light of the lamp  211  reflected on the first reflector  212  is radiated in illuminating area in accordance with the normal display size on the LCD  3  set by turning the display-size change switch  4   a  OFF. 
   In the nighttime, image brightness of the LCD  3  can be reduced by means of decreasing input voltage of the lamp  211  by operating a darkening switch (not shown) with keeping the display size and the illuminating area shown in  FIG. 17A . 
   Furthermore, in the nighttime, by moving the first reflector  212  from the position to reflect the light from the lamp  211  by the reflector change mechanism operated by turning the illuminating-area change switch  20   a  OFF as shown in  FIG. 17A , the light of the lamp  211  is reflected on the second reflector  213 . The second reflector  213  is farther than the first reflector  212  from the lamp  211  so that brightness of the light of the lamp  211  reflected on the second reflector  213  is reduced lower than the brightness of the case in  FIG. 17A  and the reflected light is radiated in large illuminating area in accordance with the display size for night on the LCD  3  set by turning the display-size change switch  4   a  ON. 
     FIGS. 18A–20  show examples of the third embodiment of the lighting device  20 . In  FIG. 18A , the lighting device  20  includes a first light source device  221  and a second light source device  224 . The first light source device  221  has a lamp  222  as a first light source and a first spherical concave reflector  223  fixed on the lamp  222  for reflecting the light from the lamp  222  to illuminate a half of the LCD  3 . The second light source device  224  has a lamp  225  as a second light source and a second spherical concave reflector  226  fixed on the lamp  225  for reflecting the light from the lamp  225  to illuminate the other half of the LCD  3 . 
   The light of the lamp  222  or the lamp  225  can be reflected on the first reflector  223  or the second reflector  226  so as to be converted to parallel light by disposing the lamp  222  or the lamp  225  at a focal point F (or in the vicinity of the focal point F) of the first reflector  223  or the second reflector  226  as shown in  FIG. 19 . If higher brightness is required, the lamp  222  or the lamp  225  may be disposed at a far side of the focal point F from the first reflector  223  or the second reflector  226 , and if wider illuminating area is required, the lamp  222  or the lamp  225  may be disposed at a near side of the focal point F to the first reflector  223  or the second reflector  226 . 
   The first light source device  221  and the second light source device  224  are mounted on a radiating direction change mechanism as shown in  FIGS. 20A ,  20 B. The radiating direction change mechanism includes a first gear  227  mounted rotatably on a predetermined position of the first reflector  223 , a second gear  228  mounted rotatably on a predetermined position of the second reflector  226  and having the same number of teeth as the first gear  227 , a third gear  229  engaging with the first gear  227 , a fourth gear  230  engaging with the second gear  228  and the third gear  229  and having the same number of teeth as the third gear  229 , and a motor  231  as driving means for rotating the third gear  229 . 
   The radiating direction change mechanism can adjust a radiating direction of the first light source device  221  and a radiating direction of the second light source device  224  to be in parallel to each other as shown in  FIG. 20A , or to intersect each other as shown in  FIG. 20B , driven by rotation of the motor  231 . 
   According to the above structure, in the nighttime, the radiating directions of the first light source device  221  and a the second light source device  224  are adjusted to be in parallel to each other as shown in  FIG. 18A  by the radiating direction change mechanism operated by turning the illuminating-area change switch  20   a  ON. Thereby, respective illuminating areas are separated so that the first light source device  221  may radiate a half of the LCD  3  and the second light source device  224  may radiate the other half of the LCD  3 , and the whole area of the large display size for night of the LCD  3  set by turning the display-size change switch  4   a  ON is illuminated by low-brightness light. 
   In the daytime, the radiating directions of the first light source device  221  and a the second light source device  224  are adjusted to intersect to each other as shown in  FIG. 18B  by the radiating direction change mechanism operated by turning the illuminating-area change switch  20   a  OFF. Thereby, the area of the normal display size of the LCD  3  set by turning the display-size change switch  4   a  OFF is illuminated by high-brightness light. 
     FIGS. 21A–25  show examples of the fourth embodiment of the lighting device  20 . In  FIGS. 21A ,  21 B,  21 C, the lighting device  20  includes a lamp  241  as a light source and a spherical concave reflector  242  disposed with a predetermined distance from the lamp  241  for reflecting light from the lamp  241  toward the LCD  3 . 
   In the lighting device  20 , the light of the lamp  241  can be radiated on the illuminating area of the LCD  3  so as to be converted to parallel light by being reflected on the concave reflector  242  when the lamp  241  is disposed at the focal point F of the concave reflector  242 , as shown in  FIG. 21A . 
   The light of the lamp  241  can be radiated on the narrower illuminating area of the LCD  3  with higher brightness than that of the case in  FIG. 21A  when the lamp  241  is disposed at far side of the focal point F from the concave reflector  242 , as shown in  FIG. 21B . 
   The light of the lamp  241  can be radiated on the wider illuminating area of the LCD  3  with lower brightness than that of the case in  FIG. 21A  when the lamp  241  is disposed at near side of the focal point F from the concave reflector  242 , as shown in  FIG. 21C . 
   Physically, the concave reflector  242  is fixed on a support device  243  having support posts and a base plate  245 , and the lamp  241  is mounted on a relative-position change mechanism (not shown). The relative-position change mechanism can move the lamp  241  from the focal point F of the concave reflector  242  toward far side thereof from the concave reflector  242  (corresponding to  FIG. 21B ) as shown in  FIG. 22A , or from the focal point F of the concave reflector  242  toward near side thereof from the concave reflector  242  (corresponding to  FIG. 21C ) as shown in  FIG. 22B . 
   When a relative position of the lamp  241  and the concave reflector  242  is set as shown in  FIG. 21B  and  FIG. 22A , the display size of the LCD  3  is set in a small size for normal displaying including daytime displaying. When a relative position of the lamp  241  and the concave reflector  242  is set as shown in  FIG. 21C  and  FIG. 22B , the display size of the LCD  3  is set in a large size for nighttime displaying. Thereby, in normal displaying, high-brightness light is radiated in small illuminating area in accordance with the small display size of the LCD  3 , and in nighttime displaying, low-brightness light is radiated in large illuminating area in accordance with the large display size of the LCD  3 . 
   As shown in  FIGS. 23A and 23B , it may be preferable that the lamp  241  is fixed at the focal point F of the concave reflector  242  and a lens is disposed between the lamp  241  and the LCD  3 . 
     FIG. 23A  shows an embodiment of disposing a convex lens  246  between the lamp  241  and the LCD  3 . The light of the lamp  241  reflected on the concave reflector  242  is condensed by the convex lens  246  so as to be radiated in a small display size of the LCD  3  with high brightness, so that it is suitable for normal displaying including daytime displaying. 
     FIG. 23B  shows an embodiment of disposing a concave lens  247  between the lamp  241  and the LCD  3 . The light of the lamp  241  reflected on the concave reflector  242  is diffused by the concave lens  247  so as to be radiated in a large display size of the LCD  3  with low brightness, so that it is suitable for nighttime displaying. 
     FIG. 24  shows a schematic perspective view of the lighting device  20  in which the lens  246  or  247  is disposed between the lamp  241  and the LCD  3 . 
     FIG. 24  shows a schematic perspective view of the lighting device  20  in which the lens  246  or  247  is mounted or dismounted between the lamp  241  and the LCD  3 . 
     FIGS. 26A ,  26 B,  27 A and  27 B show an example of the fifth embodiment of the lighting device  20 . In  FIGS. 26A ,  26 B, the lighting device  20  includes a lamp  251  as a light source, a semi-cylindrical convex reflector  252  for reflecting light from the lamp  251  and a semi-cylindrical concave reflector  253  for reflecting the light from the lamp  251 . 
   The convex reflector  252  and the concave reflector  253  are mounted on a reflector change mechanism having a stay  254  and a motor  255  whose rotating shaft  255   a  is fixed on the middle of the stay  254 , at one end of which the convex reflector  252  is fixed and at the other end thereof the concave reflector  253  is fixed. 
   When the convex reflector  252  is set in a position for reflecting the light from the lamp  251  by rotation drive of the motor  255  of the reflector change mechanism, the light of the lamp  251  diffused by the convex reflector  252  is radiated on a large illuminating area of the LCD  3  with low brightness, as shown in  FIG. 26A . 
   When the concave reflector  253  is set in a position for reflecting the light from the lamp  251  to be changed from the convex reflector  252  by rotation drive of the motor  255  of the reflector change mechanism, the light of the lamp  251  condensed by the concave reflector  253  is radiated on a small illuminating area of the LCD  3  with high brightness, as shown in  FIG. 26B . 
     FIGS. 27A and 27B  are schematic perspective views respectively corresponding to  FIGS. 26A and 26B . 
   According to the above structure, in the nighttime, the convex reflector  252  is selected by the reflector change mechanism operated by turning the illuminating-area change switch  20   a  ON, as shown in  FIGS. 26A and 27A . Thereby, the light of the lamp  251  reflected by the convex reflector  252  is radiated with low brightness in the whole area of the large display size for night on the LCD  3  set by turning the display-size change switch  4   a  ON. 
   In the daytime, the concave reflector  253  is selected by the reflector change mechanism operated by turning the illuminating-area change switch  20   a  OFF, as shown in  FIGS. 26B and 27B . Thereby, the light of the lamp  251  reflected by the concave reflector  253  is radiated with high brightness in the small area of the normal display size on the LCD  3  set by turning the display-size change switch  4   a  OFF. 
   The embodiments of this invention have been described as mentioned above, however, this invention is not limited in above, and various modification and applications can be considered. 
   For example, a display image of the LCD  3  is projected on the windshield  2  in  FIG. 1 . Instead of this, the display image may be projected on a combiner disposed on the dashboard. 
   In  FIG. 1 , the display-size change switch  4   a  and the illuminating-area change switch  20   a  are interlocked. The both switches may be interlocked with the side lamp switch. Physically, when the side lamp switch is turned OFF, the display-size change switch  4   a  and the illuminating-area change switch  20   a  are turned OFF interlockingly, and when the side lamp switch is turned ON, the display-size change switch  4   a  and the illuminating-area change switch  20   a  are turned ON interlockingly. For other example, the display-size change switch  4   a  and the illuminating-area change switch  20   a  may be turned ON/OFF by a signal of a light sensor. 
   In the example of  FIG. 4 , the angle of the part  201   c   1  of the light-guide plate  201   c  is changed. An angle of the whole of the light-guide plate  201   c  may be changed. 
   In the example of  FIG. 13 , the rear surface of the light-guide plate  201   c  is formed into the convex surface  201   c   3 . Instead of the convex surface, the rear surface may be formed into a concave surface. 
   In the example of  FIG. 16A , the first reflector  212  is mounted on the reflector change mechanism including a rack  214  fixed on the first reflector  212 , a pinion  215  and driving means having a motor  216  and a gearing portion  217  and the second reflector  213  is fixed. Instead of this, the second reflector  213  may be mounted on a reflector change mechanism having similar structure as mentioned above, and the first reflector  212  and the second reflector  213  may be changed alternately in a position to reflect the light from the lamp  211  toward the LCD  3 . 
   In the example of  FIG. 20A , the third gear  229  is driven rotatively by the motor  231  as driving means. Instead of this, the fourth gear  230  may be driven rotatively by the motor  231 . 
   Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted that various change and modifications can be made with the scope of the present invention.