US2763810A - Lighting device - Google Patents

Description

Sept M, 1956 T. HEHENKAMP ET AL 2,763,810

LIGHTING DEVICE Filed May 12, 1953 IN VEN TOR5 THEODORUS HEHENKAMP JOZEF CORNELIS MOERKENS AGENT.

United States Patent LIGHTING DEVICE Theodorus H'eiiehinarnp and Jozef Cornelis: Moerliens', Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application May 12, 1953,Serial No. 354,552 Claims priority, application Netherlands May 12, 1952 1 Claim. ((11. 315-98).

This invention-relatesto lighting devices comprising a low-pressure arc-discharge lamp, preferably a fluorescent lamp, which comprises at least one, preferably two, thermionic electrodes adapted to be heated from without, which lamp. is connected in series with an inductor to. the supply of the device, said series-circuitcomprising a switch by which the circuit is interrupted in one position and completed in another position.

Bedrooms, train compartments, aircraft, vessels, motor-buses and the like, often require the use of light sources adapted to be adjusted to full operation, to zero and to limited operation. In many cases, for example for lighting childrens rooms it is desirable that full operation of the lamp be reached only via the state of limited luminous intensity.

The present invention provides simple means for at taining this end.

In accordance with the invention, the switch has two additional intermediate positions each located between the open and the closed position, in which intermediate positions the inductor is connected directly to the supply. The inductor for each thermionic electrode adapted to be heated from without comprises an auxiliary winding which is connected thereto and is so proportioned as to produce a local discharge along the connected thermionic electrode if the inductor is connected directly to the supply.

In accordance with a further feature of the invention the switch may comprise a four-polar stator, of which three successive poles are connected to one terminal of the supply, to the electrode facing this terminal and to the other electrode respectively, the switch further comprising a rotor interconnecting three successive stator poles in any one of its four positions.

In order that the invention may be readily carried into eflect, it will now be described with reference to the accompanying drawing, given by way of example, in which:

Figs. 1, 2, 3 and 4 are schematic diagrams of a preferred embodiment of the present invention in four different states of operation.

In Figs. 1, 2, 3 and 4, the reference numerals 1 and 2 denote the terminals of a source of alternating current of, say, 220 v. 50 c./s. numeral 3 a choke comprising two auxiliary windings 4 and 5 electrically insulated from each other numeral 6 a fluorescent lamp having activated, bipolar thermionic electrodes 7 and 8 and numerals 9, 10, 11 and 12 the successive poles of the stator of a switch, whose T-shaped rotor 13 has four switch positions, each being angularly offset by 90, wherein each time three successive stator poles are connected together.

The left-hand end of the choke 3 is connected to the terminal 2 of the supply, the right-hand end of the choke being connected to the left-hand end of the thermionic electrode 8. The auxiliary winding 4 is connected to the ends of a thermionic electrode 7, the auxiliary winding 5 being connected to the ends of the thermionic electrode 8. In the case illustrated, the auxiliary winding .iatented Sept. 18, 1956 2. 5 coincides with the right-hand end of the choke winding 3} Alternatively, however, the WindingflS may be a separate winding.

The right-hand end of thechoke 3' and the lefohand end of the thermionic electrode 8 are connected to. the stator pole 11,. the left-hand end of the thermionic electrode 7 being connected to the stator pole 10.

The fluorescent lamp 6 is a low-pressure mercury vapor arc-discharge tube having an internal diameter of approximately 35 mm.,. which tube contains. a small quantity of mercury and in addition argon. under a pressure of a few mm. of mercury column. The inner wall. of thetube is covered with a layer of. material for converting. ultra-violet radiation produced in the tube into. visible light. In the normal state of operation thevoltage of the tube is approximately 60 v. and its current. approximately 0.375 a., the luminous output then being. approximately 900 lumen. If a voltage of aproximately 12 v. is set up. across the thermionic electrodes and the latter. are heated. to emission temperature, a local discharge occurs along each electrode with the result that the ends of the tube become luminous. With a current of approximately 0.7 a. through the thermionic electrodes the quantity of light then produced is approximately 10 lumen and sutficient for orientation in the room thus lighted.

The auxiliary windings 4 and 5 of the choke 3 are so proportioned that a voltage of approximately 12 v. is set up across each thermionic electrode if the choke is connected directly to the current supply. In a given case, the choke 3 may have 2150 turns, each auxiliary winding 4 and 5 may have 130 turns.

In the position of the rotor 13 shown in Fig. 1, the stator poles 10, 11 and 12 are interconnected. However, the stator pole 9 does not contact the rotor, so that the device is inoperative.

In the position of the rotor 13 shown in Fig. 2, the choke 3 is connected via the stator poles 9 and 11 directly to the terminals 1 and 2 of the supply. Local discharges are produced along the thermionic electrodes and a limited quantity of light is generated. In this instance, the lamp 6 does not ignite, since the connection is only unipolar; no contact being made with the stator pole 10.

Upon further rotation of the rotor 13 to the position shown in Fig. 3, the lamp 6 is connected in series with the choke 3 and ignites. This is the normal state of operation of the lamp with full luminous intensity.

In the position of the rotor 13 shown in Fig. 4, the choke 3 is again connected directly to the terminals 1 and 2 of the supply, so that in this position, also, luminous local discharges occur along each thermionic electrode. In this instance, the lamp 6 cannot ignite, since it is short-circuited via the stator poles 10 and 11.

Upon further rotation of the rotor 13" through the condition of Fig. 1 is again reached, wherein the device is inoperative.

Of course, the rotor 13 may alternatively be turned in the reverse direction so that, starting with the posi tion shown in Fig. 1, the positions shown in Figs. 4, 3, 2 and 1 are passed.

From this it will be seen, that the normal state of operation shown in Fig. 3 can be reached only via the states illustrated in Fig. 2 or 4. Thus, upon normal operation of the switch, the full quantity of light is not immediately directly obtained, if the device has been switched otf.

What is claimed is:

A circuit arrangement comprising a lamp having a low pressure are discharge medium and two discharge electrodes spaced apart in said medium, each of said electrodes comprising a thermionic body having two portions thereof spaced apart thereby to define a discharge space within said discharge medium, an inductor member in series connection with one of the electrodes of said lamp, means for selectively applying an alternating voltage directly across said. inductor, means for selectively applying said alternating voltage across the series connection of said lamp and said inductor, means for deriving a first voltage from said inductor and for applying it to one of said electrodes, means for deriving a second voltage from said inductor and for applying it to the other of said electrodes, said first and second voltages each having a value at least equal to the breakdown voltages of the discharge space defined by the said spaced portions of the thermionic body connected thereto when said alternating voltage is applied directly across said inducter, and switching means having a plurality of positions for producing a plurality of conditions of operability of said lamp, the first position of said switching means preventing the application of said alternating voltage across said inductor and preventing the application of said alternating voltage across the said series connection whereby said lamp is rendered inoperative thereby producing no light, the second position of said switching means permitting the application of said alternating voltage directly across said inductor and pre- 4 V venting the application of said alternating voltage across the said series connection whereby said lamp is rendered partially operative thereby producing a limited quantity of light, the third position of said switching means preventing the application of said alternating voltage directly across said inductor and permitting the application of said alternating voltage across the said series connection whereby said lamp is rendered fully operative thereby producing a full quantity of light, the fourth position of said switching means permitting the application of said alternating voltage directly across said inductor and permitting the application of said alternating voltage across the said series connection whereby said lamp is rendered partially operative thereby producing a limited quantity of light.

References Cited in the file of this patent UNITED STATES PATENTS 2,056,643 Zecher Oct. 6,- 1936 2,270,368 Zccher Jan. 20, 1942 2,337,992 Hall et al Dec. 28, 1943 2,462,336 Rufi Feb. 22, 1949 FOREIGN PATENTS 525,133 Great Britain Aug. 22, 1940

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