Monitor display unit
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a monitor display unit, and more particularly to a three-dimensional monitor display unit employing holography. 
     2. Description of the Prior Art 
     Conventionally, in order to monitor equipments mounted on a vehicle from a driver&#39;s seat, display lamps, each corresponding to each of the equipments have been provided on an instrument panel. However, in this case, the number of display lamps is restricted because of the limited space. 
     Recently, the number of equipments to be monitored has been increased due to the development of car electronics. 
     Therefore, such a monitor display unit as being capable of informing a driver of monitor information from a large number of equipments mounted on a vehicle without occupying large space has been demanded. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide a monitor display unit capable of displaying monitor information from a large number of equipments on a display surface of limited space. 
     It is another object of the present invention to provide a monitor display unit by which the arranged positions of equipments to be monitored can be certainly observed by a monitoring person with his single glance. 
     The monitor display unit of the present invention comprises a hologram dry plate for multiply recording light interference fringes of a plurality of three-dimensional images which indicate the arrangement of equipments to be monitored, image reproduction light illuminating means, each being directed toward the hologram dry plate at a different angle from each other for illuminating reproduction light toward the hologram dry plate thereby to reproduce one of the three-dimensional images on the hologram dry plate, light emitting means, each being provided in a position corresponding to each of the equipments of the three-dimensional images reproduced by the image reproduction light illuminating means, and control means for operating the image reproduction light illuminating means to reproduce a desired one of the three-dimensional images, which indicates the arrangement of equipments to be monitored and for lighting the light emitting means corresponding to the equipments to be monitored. 
     One of the reproduction illuminating means is operated by the control means in accordance with monitor signals. And one of the three-dimensional images is reproduced and at the same time the light emitting means corresponding to a specific portion of the three-dimensional images is operated. 
     According to the monitor display unit of the present invention, a three-dimensional image is displayed in accordance with the monitor signal and the specific portion of the displayed image is made emit light. This results in the monitor information can be speedily and certainly observed. 
     Furthermore, a plurality of three-dimensional images can be selectively displayed on a display surface of limited space. This results in the whole device can be made compact. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram of a monitor display unit according to the present invention, including a sectional view of a main portion thereof; 
     FIG. 2 is a front view of a dry plate, taken in the direction of the arrow A of FIG. 1; 
     FIGS. 3 and 4 are front views of dry plates on which three-dimensional images are reproduced; 
     FIG. 5 is a front view of an instrument panel of a vehicle, in which a monitor display unit according to the present invention is installed; 
     FIG. 6 is a block diagram of a control circuit; and 
     FIG. 7 is a flow chart of a computer program. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In FIG. 5, a monitor display unit M according to the present invention is installed in an instrument panel P of a driver&#39;s seat. 
     As shown in FIG. 1, the monitor display unit M has a casing 1 having an open end. The opening edge of the casing 1 is fixed to the instrument panel P by caulking. The opening of the casing 1 is covered with a hologram dry plate 2 on the same level as the panel P and the periphery of the dry plate 2 is fixed to the opening edge of the casing 1. 
     The dry plate 2 is composed of a glass base plate 21, a sensitive material 22 coated on the glass base plate 21 and a transparent protecting cover 23. 
     A three-dimensional image S1 seen from the front of a vehicle and a three-dimensional image S2 seen from the rear of a vehicle are multiply recorded as light interference fringes on the dry plate 2 as shown in FIG. 2. 
     White lamps for image reproduction 31 and 32 are supported by supporting members (not shown) on the right and the left of the front of the dry plate 2. Light from the lamps 31 and 32 enters the dry plate 2 at different incident angles from each other. 
     When the lamp 31 is lighted, the three-dimensional image S1 seen from the front of the vehicle is reproduced as shown in FIG. 3 and when the lamp 32 is lighted, the three-dimensional image S2 seen from the rear of the vehicle is reproduced as shown in FIG. 4 
     A large number of light emission diodes (LED)4 are provided on a print base plate 41 within the casing 1 in the rearward of the dry plate 2. These light emission diodes 4 are provided so as to correspond to the positions of right and left head lamps S11 of the image S1 (FIG. 3) or right and left brake lamps S21 of the image S2 (FIG. 4), for example. The light emission diodes 4 are connected to the control circuit 7 through a connector 42 provided near the under surface of the casing 1. 
     The lamps 31 and 32, an alarm buzzer 6, a lamp failure sensor 7 and an ignition key 8 are connected to the control circuit 5. And an electric current is supplied to the control circuit 5 from a battery 9. 
     To the lamp failure sensor 7 are connected brake lamps S21, parking lamps S12, head lamps S11, winker lamps S13 tail lamps S22 and a licence plate lamps S23 as shown in FIG. 6. The sensor 7 transmits signals indicating the operation of these lamps and abnormal signals indicating disconnecton or the like. 
     The control circuit 5 is composed of a microcomputer 51, an input interface 52, and an output interface 53. The lamp failure sensor 7 and the ignition key 8 are connected to the input interface 52. 
     The alarm buzzer 6, the lamps 31 and 32 and the light emission diodes 4 are connected to the output interface 53. 
     Hereinafter, the operation of the monitor display unit of the present invention will be explained in accordance with the program flowchart shown in FIG. 7. 
     In the step 101, the confirmation whether the ignition key 8 is turned on or off is effected and in the step 102, the output of the lamp failure sensor 7 is read in. 
     When any of the lamps S11 S13, S21 S23 is not abnormal, the step proceeds from the step 103 to the step 104. 
     In the step 104, the lamp 31 for image reproduction is lighted to reproduce the three-dimensional image S1 seen from the front of a vehicle. And in the step 105, the light emission diodes 4 corresponding to the operated lamps are lighted. 
     When one lamp mounted on a vehicle is abnormal in th step 103, the judgement whether the abnormal lamp is positioned in the front of a vehicle or not, is effected in the step 106. When the abnormal lamp is positioned in the front of the vehicle, the lamp 31 is lighted to reproduce the three-dimensional image S1 seen from the front of the vehicle and at the same time the light emission diode 4 corresponding to the abnormal lamp is lighted on and off (Steps 109, 110) and the alarm buzzer 6 is operated. 
     When the abnormal lamp is positioned in the rear of the vehicle, the lamp 32 is lighted in the step 107 to reproduce the three-dimensional image S2 seen from the rear of the vehicle. 
     And then the light emission diode 4 corresponding to the abnormal lamp is lighted on and off in the step 108 and at the same time the alarm buzzer 6 is operated. 
     As described above, according to the monitor display unit of the present invention, the condition of the monitored lamps are displayed on the three-dimensional images of a vehicle in positions corresponding to the actual installed position thereof. 
     Therefore, the monitor information can be judged speedily and certainly by an occupant. 
     Furthermore, a plurality of three-dimensioinal images can be previously recorded on a dry plate of the monitor display unit of the present invention. By selectively reproducing these three-dimensional images, a large amount of monitor information can be displayed without requiring large space for the monitor display unit. 
     The monitor display unit of the present invention can be also employed for monitoring other equipments mounted on a vehicle such as equipments of an engine. In addition, the monitor display unit of the present invention can be also employed for monitoring other than equipments of a vehicle. 
     In the above described display unit, the lamp for image reproduction can have a green filter therewithin. In this case, cleaner and distinct three-dimensional images can be obtained.