Abstract:
A large sized display device including a number of heat generating display elements such as lights, etc. is provided internally with a cooling mechanism which prevents external moisture, etc. from creating problems in the internal equipment.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a movable large display device for displaying characters and images, and more particularly, to a display device wherein the internal air is circulated by air conditioners provided inside of the display device body, to thereby cool the heat generating elements of a light emitting section which is adapted to display characters and images, and to protect the internal equipment from problems which might otherwise be caused by the external air including dust and moisture. 
     Portable display devices of large size are known in the art, as for example in U.S. Pat. No. 4,110,792 to Long. However, this device is removed in both design and character from that of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view outlining a movable large display device according to one emodiment of this invention; 
     FIG. 2 is a sectional side view of the display device shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the invention will now be described. With reference to FIGS. 1 and 2, reference numeral 1 designates a display device body which is moved by a trailer. A light emitting display section 2 is disposed on the front wall of the display device body 1, the section 2 comprising a plurality of light emitting elements (such as monochromatic cathode ray tubes or colored light emitting tubes) and having a cooling air passage on the rear wall, which is formed by a removable separator 3. Air cooling type air conditioners 4 are provided inside of the display device body 1, and a duct 5 is connected to each air conditioner 4, the duct 5 having air blowing outlets 6 through which cooling air is directed to the cooling air passage. The air conditioners are installed on the internal wall of the display device body 1 and have two openings, namely, an external cooling air inlet 7 and an external air discharging outlet 8. The two openings 7 and 8 are provided with covers 9 which are vertically swingable to close when the large display device is moved or the air conditioners 4 are not in operation. 
     The large display device thus constructed will now be described in more detail. 
     The light emitting display section 2 defines a kind of duct, which is the aforementioned cooling air passage, between its rear surface and the separator 3. Cooling air from the air blowing outlet 6 flows along the rear wall of the light emitting display section 2 to effectively cool the latter, and is then introduced to the air conditioners 4 from below the light emitting display section 2. 
     In FIG. 2, the broken line indicates the flow of cooling air. 
     Since the separator 3 can be readily removed, inspection or replacement of the light emitting display section 2 can be readily achieved. In each air conditioner 4, the cooling air is introduced thereinto through a lower portion of the rear wall of the air conditioner and is discharged through an upper portion of the rear wall. In the air conditioner 4, the internal circulating air is completely separated from the external air. 
     As is apparent from the above description, according to the invention, only the internal air is circulated for cooling. Therefore, the internal equipment is not affected by the external air, that is, equipment trouble due to external airborne dust and moisture will not be caused. Covers which can be vertically swung are provided for the external air intake and the external air discharging outlet, and therefore the formation of an external air short-circuiting loop is prevented.