WO1995034087A1

WO1995034087A1 - Gas discharge light

Info

Publication number: WO1995034087A1
Application number: PCT/US1995/007104
Authority: WO
Inventors: Ferenc Mohacsi
Original assignee: Fallon Luminous Products Corporation
Priority date: 1994-06-06
Filing date: 1995-06-05
Publication date: 1995-12-14
Also published as: AU2766795A

Abstract

A gas discharge light bulb (20) of the flat panel type includes a plurality of channels (32) formed in at least one glass panel (30). A second glass panel (28) covers the channels (32) of the first glass panel (30). A plurality of windows (46) are associated with the plurality of channels (32) to enable emission of visible light from the plurality of channels (32) through the windows (46). A gas discharge light source within the plurality of channels (32), provides the light which is emitted through the windows (46).

Description

GAS DISCHARGE LIGHT

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to gas discharge lighting and, more particularly, to directional high density low pressure gas discharge light bulbs.

There are basically two types of tube light bulbs, hot cathode and cold cathode, which exist today. Hot cathode tubes popularly known as fluorescent tubes are low pressure mercury vapor discharge tubes which produce light by passing electric current through a gas. The collision of electrons into gas molecules causes the electrons to transfer some of their kinetic energy to the gas molecules which, in turn, when returning to a stable condition, radiate the gained energy. The spectral distribution of the radiated energy is characteristic of every gas or gas mix. In the case of mercury vapor, the vast majority of the radiation is in short ultraviolet light waves in the 254 nanometer wavelength range. This type of light source is produced in glass tube envelopes of various diameters.

The inside of the tubes are coated with fluorescent powder which absorbs the short wave ultraviolet radiation and emits energy in the visible spectrum. The ends of the tubes are fitted with cathodes of triple wound tungsten filament. The cathodes provide the necessary electrons for the electric current flow, however, to be able to liberate the energy, the cad ode is heated to a high enough temperature such that no extra potential is required to initiate current flow. The life expectancy of hot cathode lamps is in the range of 7,000 to 10,000 hours. The life expectancy is effected by sputtering of the relatively delicate cathode filament.

Cold cathode tubes popularly known as neon tubes are another form of low pressure gas discharge light sources. The cathode for cold cathode tubing has traditionally been made of high purity soft iron having a cylindrical or conical shape and is usually nickel plated to prevent excessive oxidation before processing takes place. The electrons for the tube current are provided by surface emission and therefore the tube current and the physical size of the cathode is in a linear relation. To liberate the electrons from the surface of the cold cathode, the electrons must be accelerated to a velocity which is adequate to leave the surface. Cold cathodes in theory should last indefinitely. However, in practice, useful life is expected to exceed 20,000 hours.

Apart from the red discharge produced by neon gas, other colors are a result of short wave radiation emitted by mercury vapor being converted to visible light by the fluorescent phosphor on the inside wall of the glass envelopes. The glass envelope is normally in a tube form and the phosphor is introduced to the inside surface in a suspension. The suspension is either poured down from the top of the tube in a way that it covers all around the inside of the glass and washes down the full length of the tube (downflash) or the tube is flooded from the bottom end and allowed to drain (upflushed). After draining and controlled drying, the result in both cases is a reasonably even coating of phosphor on the inside of the glass tubing.

The coating density needs to be carefully controlled as it effects the light output of the lamp. If the coating is too heavy, much of the visible light emitted by the phosphor will be absorbed or reflected back into the inside of the tube by the phosphor particles which are near the glass wall. If the coating is light, part of the ultraviolet radiation will miss the phosphor particles and will not be converted to visible light. Therefore, the efficiency will suffer.

U.S. Patent Nos. 4,584,501; 4,990,826; 5,066,257; and 5,036,248, the specification and drawings of which are herein expressly incorporated by reference, illustrate various types of flat plate illumination devices. These patents illustrate glass plate illumination devices which include a phosphor coating entirely about the tube envelope. Thus, the emitted light reflects into and through the phosphor coating.

The present invention provides the art with a directional high light density gas discharge light bulb. The present invention provides a plate having at least one channel with the channel coated or non coated with a phosphor coating and a window which enables light emission through the window. The window is positioned with respect to the channel such that the light is directed through the window. The light reflecting through the window is of greater intensity and is directional due to the window. The invention may be utilized in various types of lighting applications, particularly in the automotive field as turn signal indicator lights, rear and stop lights.

From the following detailed description taken in conjunction with the accompanying drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a gas discharge light bulb in accordance with the present invention.

Figure 2 is a front plan view of the light bulb of Figure 1.

Figure 3 is an unexploded view of the light bulb of Figure 1.

Figure 4 is a cross sectional view along line 4-4 of Figure 1.

Figure 5 is an additional embodiment in cross section like that of Figure 4.

Figure 6 is a perspective view of an additional embodiment in accordance with the present invention.

Figure 7 is a front plan view of the light bulb of Figure 6. - 4 - Figure 8 is an exploded view of the light bulb of Figure 6.

Figure 9 is a cross sectional view of Figure 6 along line 9-9 thereof.

Figure 9A is the same view as Figure 9 with the phosphor coating on the side of the channels.

Figure 10 is a cross sectional view of Figure 11 along line 10-10 thereof.

Figure 10A is the same view as Figure 10 with the phosphor coating on the side of the channels.

Figure 11 is a plan view of another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning to the figures, specifically Figure 1, a gas discharge light bulb is illustrated and designated with the reference numeral 20. The light bulb is of the flat panel type with a tube envelope 22, having a plasma gas therein, and electrodes or cathodes 24 and 26.

The bulb 20 includes a front plate 28 and a back plate 30. The front plate 28 is ordinarily a desired size and shape sheet of glass having desired glass characteristics. The back plate 30 includes a plurality of channels 32 connected with one another by grooves 34 at their ends. The channels 32 may be in a serpentine pattern or may be longitudinally parallel with one another. The channels 32 are separated by a portion 31 of the glass plate 30 having a thickness of about 2 mm. At one end of channels is an electrode receiving portion 36 and 38 which house the electrodes 24 and 26. The back plate 30 includes an evacuation tube 40 which enables the tube envelope 22 to be evacuated to form a vacuum within the tube 22 after the plates are bonded together to form the light bulb 20. A cap 42 is positioned onto the evacuation tube 40 to protect the tube. The electrodes include leads 25, 27 which extend from the light bulb 20 which enables the light bulb to be connected with an electrical source. Further, additional electrical elements, such as transformers and the like are connected with the leads.

Prior to bonding the cover glass plate 28 with the rear plate 30, a phosphor coating 44 is added in the channels 32 and grooves 34. As best seen in Figure 4 the channels 32 include the phosphor coating which may cover any portion of the inner surface of the channels and grooves from 0 to 100% of the inner surface of the channels and grooves. Once the front glass plate 28 is bonded to the rear plate or panel 30, the front plate 28 provides an uncoated window 46 for the tube envelope 22 as seen in Figure 4. The window 46 enables light to exit the light bulb tube envelopes 22 without significant interference, thus providing high density visible light. The intensity of the light can be increased when wattage to the electrodes is increased, providing brighter visible light.

Turning to Figure 5, an additional embodiment is shown. This embodiment is similar to that previously described with the exception that the plate 30' includes channels 32' which extend entirely through the glass. An additional backing glass plate 50 is positioned opposing the front glass plate 28. The glass plate 50 includes the evacuation tube and the electrodes continue to be mounted in the end of the channels. As illustrated in cross section in Figure 5, the channel has an overall U shape. The legs of the U are coated with the phosphor coating. Thus, windows 51, 53 are created on both the front and rear cover plates 28 and 50 to enable visible light to emit from both sides of the light bulb 20.

The light bulb 20 is a low pressure gas discharge light utilizing cold cathodes. The cathodes for cold cathode tubing are traditionally made of high purity soft iron which is cylindrical or conically shaped and usually nickel plated to prevent excessive oxidation before processing takes place. The electrons for the tube current is achieved by surface emission from the electrodes or cathodes. Thus, the tube current and the physical size of the cathode is in a linear relationship. To liberate the electrons from the surface of the cold cathode, the

electrons are accelerated to a velocity which is adequate to leave the surface. This excitation is achieved by electrical current. Cold cathodes in theory should last indefinitely, but in practice, useful life is expected to exceed about 20,000 hours.

Apart from the red discharge produced by neon gas, all other colors are the result of short wave radiation emitted by a mercury vapor being converted to visible light by the fluorescent phosphor coating on the inside surface of the glass envelopes. The glass envelope is normally in the form of a tube and the phosphor is introduced to the inside surface in a suspension.

A method of making the above described light bulb is as follows. The plate 30 is provided and the channels 32 and grooves 34 are cut into the plate by desired methods. The grooves 34 may extend into the plate or they may extend through the plate, in which case the backing plate 50 would be necessary in the process. The desired portion of the channels 32 and grooves 34 is coated with the phosphor coating. As mentioned above, 100% of the channels 32 and grooves 34 or a lesser extent to 0% of the channels or grooves may be covered with the phosphor coating. After the plate 30 has been coated with the phosphor, the electrodes are added. Next, the front plate 28 and, if necessary, the rear plate 50 is bonded or melted with the plate 30. Thus, electrodes 24, 26 and the front of the discharge tube are hermetically sealed to the phosphor coated plate 30. After sealing, the air is evacuated out of the tube 40 while heating the electrodes in order to remove any contamination which may have been trapped in the metal and also conferred to the emissive material which may have coated the cathode. The envelope is filled with gas, typically a mix of argon, neon or the like, to the required pressure and the mercury is added. Thus, since the cover plates do not include a phosphor coating, a clear window is formed in the light bulb which allows directional visible light to exit the light bulb without interruption. The phosphor particles, which are directly exposed to the ultraviolet radiation, absorb the majority of the radiation and produce visible light in the portion of absorption.

Thus, the inner surface of the phosphor coating is brighter than the outer surface. Some of the visible radiation produced on the inner surface of the light bulb is reflected by the white body color of the phosphor and a portion absorbed. The window enables the brightest surface to be visible while permitting a greater portion of the reflective light to pass through the window.

Turning to Figures 6 through 11, additional embodiments of the present invention are shown. Figure 6 illustrates a light bulb in accordance with the present invention and is designated with the reference numeral 60. The light bulb includes a tube envelope 62 as well as electrodes 64 and 66.

Turning to Figures 7 and 8, the light bulb includes a front glass plate 70, a middle channel plate 72, a middle backing plate 74, a second channel plate 76 and a rear backing plate 78. The front and rear backing plates are like those previously described. The two channel plates 72 and 76 have channels 80 and 82 which extend all the way through the plates 72 and 76. The middle backing plate 74 is similar to the other front and rear plates, however, it includes apertures 86 to enable communication between the channels of the plates 72 and 76. Also, generally only one of the channel plates 76 includes the extending channels to enable the electrodes 64, 66 to be positioned within the channels.

A phosphor coating 75 may be positioned on the sides of the channels 80, 82 in the plates 72 and 76 and a coating, aligned with the channel, may be silkscreened onto the middle and rear plates 74 and 78. The middle and rear plates make up the back of the channels in this particular embodiment. Thus, in the event that the bulb is to have a single window 81, then the plates 74 and 78 are coated with a phosphor coating 77, as seen in phantom in Figure 8. In the event that dual windows are desired, the plates 74 and 78 would not be coated with a phosphor coating, or alternately plate 74 is coated on both sides. As seen in Figure 9, the coating is on the legs and web portion of the U shaped channels, however, in embodiments where opposing windows 83 are desired, the silkscreen phosphor coating would not be utilized on the middle and rear plates 74 and 78. Also, generally in these embodiments where dual windows are required, the opposing sides of the channels are coated with a phosphor coating. However, in some embodiments, no phosphor is coated on any of the channels or the middle and rear plates.

Ordinarily, the channels 80, 82 of plates 72 and 76, when they are combined into the bulb 60, are offset with respect to one another, see Figures 7 and 9. This enables one channel to be adjacent to the next channel in the other glass plate. Thus, the envelope tubes are one next to the other, on top of one another which provides a very high intensity and dense visible light. With windows open through the different layers of glass, the visible light is very dense and close together and is reflected through the windows. As seen in Figure 9, a window 81 is created from the top plate 70 and middle plate 74 and first channel plate 72, with respect to the second channel plate 76, to reflect visible light out through the front plate 70. Likewise, if such is the case to reflect out the rear plate 78, the same occurs with respect to the middle plate 74 and second channel plate 76 with respect to the first channel plate 72.

Figure 10 shows an additional embodiment of the present invention. In Figure 10, a corrugated glass panel 90 is provided between front and rear cover plates 92, 94. The corrugated sheet 90 includes several U shaped channels as seen in cross section in Figure 10. The channels 96 include a phosphor coating 98 as explained above in the desired percentage on the inner surface of the corrugated sheet 90. Thus, the corrugated sheets 90 form channels opposing one another in opposite directions with respect to the front and rear cover plates 92, 94. If a one directional light bulb is desired, the rear sheet 94 would include a phosphor coating, aligned with the channels, silkscreened onto it in the particular channel such that the web of the channel would not contain the phosphorous coating and the legs of the channel would include the phosphor coating as well as the backing sheet. In the event windows opposing one another are desired, only the legs of the channels of the corrugated panel 90 would be coated with the phosphor coating. Thus, the corrugated panel 90 provides dense visible light to shine through the windows and provides tube envelopes which are adjacent one another.

The light bulb in accordance with Figure 6 is produced in a manner similarly to that described above. Here, the channeling plates are provided with channels cut through the glass panels. If it is desired, they are phosphored on their opposing sides. Likewise, the middle or separator panel, which includes the apertures, is silkscreened, if desired, with a phosphor coating aligned with the channels of the first channel plate. The second channel plate has its opposing sides coated with the phosphor coating. If desired, the rear plate is coated to align with the phosphored sides of the second channel sheet.

The cover front plate is secured with the first channeling plate which, in turn, is secured with the separator middle backing plate which is followed by the second channeling plate and the rear cover plate. The rear cover plate includes the evacuation tube to evacuate the tube envelope. The electrodes are positioned into the channels in the second channel plate and all the plates are placed one on top of the oilier and heated to bond the plates with one another. After the heating, a vacuum is applied to the vacuum tube to evacuate the tubes pulling out any impurities and readying the tube to receive the gas and mercury vapor. As mentioned above, the argon or neon gas as well as the mercury is inserted into the tube envelopes to provide the plasma for light generation.

The present invention provides a panel light bulb which is relatively thin and flat with respect to other types of light bulbs. This type of light bulb is highly desirable for use in the automotive field for turn signal lights as well as rear and stop lights. The bulb is flat and has a thickness of about 0.5 to .75 inches and eliminates the space required for housings which generally accompany the turn signal and rear and stop lights. Thus, the present invention enables the automotive manufacturer to provide rear lights and recover 3 to 4 inches in trunk space and front engine compartment space where these housings have previously occupied space in the automobile.

While the above detailed description describes the preferred embodiment of the present invention, the invention is susceptible to modification, variation, and alteration without deviating from the scope and fair meaning of the subjoined claims.

Claims

WHAT IS CLAIMED IS:

1. A gas discharge light comprising: at least one glass panel; a plurality of channels formed in said at least one glass panel, said channels adjacent one another; a second glass panel covering said channels, said second glass panel secured with said first panel; a window associated with said plurality of channels for enabling emission of visible light from said plurality of channels; and gas discharge light source means for providing light within said plurality of channels.

2. The gas discharge light according to claim 1 wherein said channels have an inner surface which may include a phosphor coating.

3. The gas discharge light according to claim 2 wherein said phosphor coating covers from 0 to 100% of said inner surface of said channels.

4. The gas discharge light according to claim 3 wherein said channels have an overall U shape in cross section.

5. The gas discharge light according to claim 4 wherein at least legs of said U include said phosphor coating.

6. The gas discharge light according to claim 1 wherein each channel includes a plurality of windows, said windows opposing one another.

7. The gas discharge light according to claim 1 further comprising a third glass panel, said third glass panel having a plurality of channels and said third glass panel positioned adjacent said at least one panel.

8. The gas discharge light according to claim 7 wherein said third glass panel is positioned with respect to said at least one panel such that said channels of said third panel are offset with respect to said channels of said at least one glass panel.

9. The gas discharge light according to claim 8 wherein said pluralities of channels are in communication with one another.

10. The gas discharge light according to claim 1 wherein said at least one glass panel is corrugated and a third glass panel covering said channel is positioned opposing said second glass panel.

11. A method of making a gas discharge light comprising: providing a first panel having a plurality of adjacent channels; securing a second glass panel to said first glass panel for enveloping said channels; providing a window in each said enveloped channels for enabling emission of visible light; coupling a gas discharge light source means with said panels for providing

light within said plurality of channels.

12. The method of claim 11 further comprising adding a phosphor coating of said channels such that said coating covers 0 to 100% of said channels.

13. The method of claim 11 further comprising providing a third glass panel having a plurality of channels.

14. The method of claim 12 and positioning said third glass panel with said first glass panel such that said channels in said first and third glass panel are offset with respect to one another.