Patent Publication Number: US-4320324-A

Title: Flat fluorescent lamp

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a fluorescent lamp with discharge electrodes at both of its ends, and more particularly to a flat type fluorescent lamp which is rectangular in overall shape and which is formed by connecting rectangular dish-shaped halves. 
     The fluorescent lamp of the prior art is, in general, constructed in such a manner that it has discharge electrodes at both its ends, irrespective of the shape of the lamp. Voltage supply terminals are mounted on the stems which have exhaust pipes for facilitating the mounting of these electrodes. After a discharge electrode is connected between the terminals of each stem, a stem is mounted to each end of the fluorescent lamp. Therefore, the fluorescent lamp has a stem and voltage supply terminals projecting from each of its ends. Since a base is connected to the ends, it is necessary that the terminals for mounting the sockets project from both ends of the fluorescent lamp. 
     When such a fluorescent lamp serves as a projecting type display lamp used in corridors and so on, the sockets must be formed on the wall side and on the passage side. Even if a socket mounting frame is used, it is frequently the case that the base is exposed or the frame of the socket mounting portion is extremely wide at the passage side. Thus, the appearance will not be very attractive. Further, since the fluorescent lamp is a bayonet socket type, the mounting condition is unstable unless a spring biasing force is exerted on the socket toward the lamp. Thus, the lamp has the disadvantage of requiring a more complicated construction for providing the spring biasing force; further, the construction of the frame itself is complicated, and the number of manufacturing processes increases, resulting in higher cost. 
     The present invention was made to overcome these defects, and a major object of the invention is to provide a flat type fluorescent lamp in which the voltage supply terminals are provided at only one end of the lamp. 
     Another object of the invention is to provide a fluorescent lamp suitable for use as a projecting type display lamp of the kind used in corridors and so on. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a flat type fluorescent lamp comprises a pair of generally rectangular, dish-shaped halves each having a flat surface, said dish-shaped halves facing either other and being connected together at peripheral portions thereof to form a hollow body; a stem disposed at only one end of the connected hollow body, the stem containing an exhaust pipe and voltage supply terminals; a first discharge electrode coupled to the voltage supply terminals and being in the hollow body at said one end; a second discharge electrode mounted in the hollow body at the opposite end of the hollow body; a pair of lead wires connected at one end to the second discharge electrode, the lead wires extending to the side of the stem around the outside marginal area of the dish-shaped halves; and a base having two pairs of pin electrodes, the base being located in the vicinity of the stem; the other ends of the lead wires and the voltage supply terminals being connected to respective ones of the pin electrodes. 
     These objects are attained in accordance with the invention in which a pair of rectangular halves are made to face each other for connection, the overall shape of the fluorescent lamp is rectangular, a mount with an exhaust pipe and voltage supply terminals is attached to only one end, the other end faces a discharge electrode of said mount by attaching the discharge electrode to lead wires, the lead wires are gathered at the mounting terminal side for connecting them to the base, the mounting portion of the socket is disposed at one end of the fluorescent lamp, the installment of the fluorescent lamp is easy, the socket usually required at the passage side for a projecting display lamp for corridors is unnecessary, the lamp is only inserted into the socket disposed on the wall side, no additional exposed wiring is necessary and the overall appearance is improved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view illustrating the flat fluorescent lamp of the invention; 
     FIG. 2 is a front view illustrating the wiring of the flat type fluorescent lamp in which one of the dish-shaped halves is cut away; 
     FIG. 3 is a front view illustrating the finished flat type fluorescent lamp; 
     FIG. 4 is a front view illustrating a frame in which the flat type fluorescent lamp of the invention is installed; 
     FIG. 5 is an enlarged sectional view taken along the line V--V of FIG. 4; 
     FIG. 6 is an enlarged front view of the base of the flat type fluorescent lamp of the invention; and 
     FIG. 7 is a sectional view taken along the line VII--VII of FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the embodiment shown in the drawings, 1 designates dish-shaped halves made of glass which are formed in a generally rectangular shape. The flat type fluorescent lamp is formed by facing the dish-shaped halves toward each other and connecting them together. Since the dish-shaped halves 1 are similar, the construction of only one of the dish-shaped halves 1 will be explained. The dish-shaped half includes a projecting portion 2, forming a rectangular discharging tube part, and a flange 3 around projecting portion 2. A recess 4 for engaging with a stem, to be explained further hereinafter, is formed in the flange portion 3a of one of the short sides of the rectangular body. Grooves 5, 6 are formed in the flange 3 and cross both of the long sides at points close to the other short side flange portion 3b. 
     Before a pair of dish-shaped halves 1 of such construction are connected together, a stem engages with the recess 4, and the front ends 8a, 9a of the lead wires 8, 9 are placed in the grooves 5, 6. The front ends 8a, 9a are made of dumet wire, or an alloy of iron, nickel, or chrome. The remaining length of each lead wire 8, 9 disposed outside the lamp is made of copper. An exhaust pipe 11 is integrally formed with the aforementioned stem 7 which is made of glass. A pair of voltage supply terminals 12, 13 comprising dumet wires, or the like, are mounted thereon. A discharge electrode 14 is mounted across the front ends of the voltage supply terminals 12, 13 opposite a discharge electrode 10 which is connected across lead wire ends 8a,9a. The stem 7 and the lead wires 8, 9 are disposed at predetermined places. A sealing material such as soda glass or frit glass is applied to the flanges 3 of the pair of dish-shaped halves 1, where they are in contact with each other, to keep the flanges 3 impermeable and thus form a flat type fluorescent lamp which is generally of rectangular form. It is of course understood that sealing material is also applied to the recess 4, in which is disposed the stem 7, and to the grooves 5, 6, in which are disposed the lead wires 8, 9, for rendering these parts impermeable. 
     After the flanges 3 are sealed, the inner air is either discharged or substituted with an inert gas through the exhaust pipe 11 which is closed thereafter. The lead wires 8, 9 are attached to the body along the outside of the flanges 3 toward the stem 7. The other ends of the lead wires 8b, 9b are collected at the same side of the lamp as the voltage supply terminals 12, 13. 
     The connected and sealed flanges 3 are covered with an ornamental frame 15 (FIGS. 3-5) made of a synthetic resin or rubber. The voltage supply terminals 12, 13 are connected to a base 18 (FIGS. 3 and 6) and to a pair of pin electrodes 16, 17. The base 18 is securely attached to one side of the fluorescent lamp by an adhesive such as epoxy resin. 
     The frame 15 is rectangular so as to correspond to the shape of the fluorescent lamp (see FIG. 4). Grooves 19 (see FIG. 5) is formed on the inner surface of frame 15, securely engaging with the flanges 3 of the fluorescent lamp. Grooves 20, 21 (FIG. 5) are also formed in frame 15 on both sides of the groove 19 for receiving a transparent or semi-transparent display plate. 
     The base 18 is made of insulating materials such as melamine resin or urea resin. Two pairs of pin electrodes 16, 17 each consisting of conductive metal material such as brass or alloys including nickel or chrome, are mounted on the base 18. The pin electrodes are made of hollow pipe materials. The voltage supply terminals 12, 13 are inserted in the pin electrodes 16, and the free ends of the lead wires 8, 9 are respectively inseted in the pin electrodes 17. The sections of these voltage supply terminals projecting from the pin electrodes are soldered, and the unnecessary parts of them are cut away. The flat type fluorescent lamp of the invention is manufactured in this manner. Since the fluorescent lamp itself has a flat light-emitting surface, the display part 22 such as &#34;CONFERENCE ROOM&#34; can be directly displayed on it, or alternatively, a desired colored display can be attained using other suitable display plates. 
     As has been described, the flat type fluorescent lamp is quite useful as a display lamp since it is manufactured by connecting dish-shaped halves and therefore direct display on a flat surface is possible. The exhaust pipe and the voltage supply terminals are collected only at one end of the flat type fluorescent lamp so that no projecting portions are formed at the other end of the lamp. Thus, electrical wiring and exchange of new lamps are easy and the appearance is improved when this lamp is used as a projecting type display lamp of the type used in corridors. Further, since no comparatively heavy parts, such as the base and the voltage supply terminals, are included at the other end, that is, the front or free end of the projecting display lamp, the load exerted by the projecting end is less and the center of gravity is shifted toward the mounting side. Thus the fluorescent lamp of the invention is advantageous in that the mounting conditions are stable.