Patent Application
20140034218
This disclosure relates generally to vacuum insulated glass (VIG) window unit configurations and methods for making VIG window units. The disclosure more particularly relates to techniques for activating getters in a process of making VIG window units. In certain example embodiments, at least one getter is activated during and/or at the end of a pump-out process in which the cavity between the substrates is evacuated (e.g., pumped-down). Getters are typically subdivided into two main classes: evaporable getters (EGs) and non-evaporable getters (NEGs). While this disclosure is applicable to both EG and NEG type getters, it is particularly useful for getters including NEG type getter material which tend to have a lower activation temperature(s).
Vacuum insulating glass (VIG) window units typically include at least two spaced apart glass substrates that enclose an evacuated low-pressure space/cavity therebetween. The substrates arc interconnected by a peripheral edge seal and typically include spacers between the glass substrates to maintain spacing between the glass substrates and to avoid collapse of the glass substrates that may be caused due to the low pressure evacuated environment that exists between the substrates. Some example VIG configurations are disclosed, for example, in U.S. Pat. Nos. 5,657,607, 5,664,395, 5,657,607, 5,902,652, 6,506,472 and 6,383,580 the disclosures of which are all hereby incorporated by reference herein in their entireties.
A pump-out tube 8 may be hermetically sealed by, for example, solder glass 9 to an aperture/hole 10 that passes from an interior surface of one of the glass substrates 2 to the bottom of an optional recess 11 in the exterior surface of the glass substrate 2, or optionally to the exterior surface of the glass substrate 2. A vacuum is attached to pump-out tube 8 to evacuate (e.g., pump-down) the interior cavity 6 to a low pressure that is less than atmospheric pressure. After evacuation of the cavity 6, a portion (e.g., the tip) of the tube 8 is melted to seal the vacuum in low pressure cavity/space 6. The optional recess 11 may retain the sealed pump-out tube 8.
As shown in
Disclosed herein are techniques for activating getters in a process of making VIG window units. In certain example embodiments, at least one getter is activated during and/or at the end of a pump-out process in which the cavity between the substrates is evacuated.
In certain example embodiments of this invention, there is provided a method of making a vacuum insulated glass (VIG) window unit, the method comprising: having first and second substantially parallel glass substrates, a plurality of spacers and a seal provided between the first and second substrates, a cavity to be evacuated to a pressure less than atmospheric pressure located between the glass substrates, and at least one getter provided in the cavity; and activating the getter during and/or substantially at an end of an evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In certain example embodiments of this invention, there is provided a method of making a vacuum insulated glass (VIG) window unit, the method comprising: having first and second substantially parallel glass substrates, an array of spacers and a seal provided between the first and second substrates, and a cavity to be evacuated to a pressure less than atmospheric pressure located between the glass substrates, and a getter supported by the first substrate; and directing a laser beam through a pump-out tube supported by the second substrate so that the laser beam impinges upon the getter and activates the getter.
These and other embodiments and advantages are described herein with respect to certain example embodiments and with reference to the following drawings in which like reference numerals refer to like elements throughout the several views, and wherein:
Certain example embodiments will be described in detail herein with reference to the foregoing drawings in which like reference numerals refer to like elements throughout the several views. It will be understood that the embodiments described herein are intended to be illustrative, not limiting, and that those skilled in the art will understand that various modifications may be made without departing from the true spirit and full scope of the claims appended hereto.
With reference to
In certain embodiments, the transparent glass substrates 2, 3 may be approximately the same size. However, in certain other example embodiments, one glass substrate 2 may be larger than the other 3 to provide, for example, an approximately L-shaped step proximate an edge of the VIG unit. One or both of the glass substrates 2, 3 may also optionally include at least one coating material (not shown) such as, for example, and without limitation, a low-E coating. It will be understood that various coatings may be present on an interior surface of at least one of the glass substrates 2, 3, and that such coatings provide various beneficial performance characteristics to the VIG window unit 1. In certain example embodiments, a low-E coating for blocking IR radiation is provided on the interior surface 3a of substrate 3 (as opposed to substrate 2 which supports the getter(s)). In certain example embodiments, the VIG window unit has a visible transmission of at least about 30%, more preferably of at least about 40%, even more preferably of at least about 50%, and even more preferably of at least about 60% or 70%.
An array of support pillars/spacers 5 is located between the glass substrates 2, 3 to maintain the spacing of the substrates in view of the lower than atmospheric pressure that is ultimately provided in low pressure evacuated cavity/space 6 between the substrates 2, 3. In certain example embodiments, the spacers may have a height, for example, of about 0.1 to 1.0 mm, more preferably from about 0.2 to 0.4 mm. The height of the spacers 5 may approximately define the height of the vacuum/evacuated cavity 6. As noted above, the spacers 5 are preferably of a size that is sufficiently small so as to be visibly unobtrusive. According to certain example embodiments, the spacers 5 may be made of or include solder glass, glass, ceramic, metal, polymer, or any other suitable material. Additionally, the spacers 5 may be, for example, generally cylindrical, round, spherical, dime-shaped, C-shaped, pillow-shaped or any other suitable shape.
A pump-out tube 8, that may be hermetically sealed for example using solder glass 9, is provided through a hole 22 in one of the glass substrates, e.g., substrate 3. The pump-out tube 8 is used in a process to evacuate the cavity 6 between the substrates 2, 3, such as, for example, by attaching a vacuum pump to the distal end of pump-out tube 8 and evacuating the cavity 6 to a low pressure, e.g., a pressure lower than atmospheric pressure. Alternatively, the cavity may be evacuated in a low-pressure chamber. In a preferred example, a pressure in the cavity 6 following evacuation is, for example, preferably below about 10-2 Torr, and more preferably below about 10-3 Torr, and even more preferably below about 5×10-4 Torr. During the evacuation process, the VIG unit may be subject to heating to help with the evacuating process, e.g., temperature(s) from about 150-300 degrees C. After evacuating the cavity 6, the pump-out tube 8 may be sealed, for example, by melting the tip 8a of the tube 8 by any suitable means, such as, for example, by laser. According to certain example embodiments, the pump-out tube 8 may or may not fully extend through the hole 22 to be flush with the interior surface 3a of the glass substrate 3, and may be left just short of the interior surface 3a by a distance of, for example, and without limitation, up to about up to 0.1 mm from the interior surface 3a in certain example embodiments.
After the pillars/spacers 5 are positioned on bottom glass substrate 2, at least one getter (e.g., EG type) 32 is positioned in getter recess 14. Then, the edge seal material is deposited on substrate 2. The other substrate 3 is brought down on substrate 2 so as to sandwich spacers/pillars 5, the glass frit solution, and getter 32 between the two substrates 2, 3. The assembly including the glass substrates 2, 3, the spacers/pillars 5, getter 32, and the edge seal material is then heated to a temperature (e.g., of at least about 500° C.) at which point the edge seal material melts, wets the surfaces of the glass substrates 2, 3, and ultimately forms a hermetic peripheral/edge seal 4.
After formation of the edge seal 4 between the substrates, a vacuum is drawn via the pump-out tube 8 to form low pressure space/cavity 6 between the substrates 2, 3. To maintain the low pressure in the space/cavity 6, substrates 2, 3 are hermetically sealed via edge seal 4, and the small spacers/pillars 5 are provided between the substrates to maintain separation of the approximately parallel substrates against atmospheric pressure. Once the space 6 between substrates 2, 3 is evacuated, the pump-out tube 8 may be sealed, for example, by melting its tip using a laser or the like. After evacuation of the cavity/space 6 to a pressure less than atmospheric, sealing of the pump-out tube may be accomplished by heating an end 8a of the pump-out tube 8 to melt the opening and thus seal the cavity of the VIG window unit. For example and without limitation, this heating and melting may be accomplished by laser irradiation of the tip 8a of the pump-out tube 8.
In various embodiments herein, the substrates 2 and/or 3 of or including glass may be from about 1-6 mm thick, more preferably from about 3-5 mm thick, with an example glass thickness being about 4 mm. In various embodiments herein, recess 14 may have a depth of from about 1.5 to 2.5 mm, with an example recess depth being about 2 mm in an example 4 mm thick sheet of glass. In certain example embodiments of forming the substrates 2 and 3, the getter recess(es) 14 is/are formed in one of the respective glass sheets, then the glass sheets may optionally be thermally tempered, then optionally a low-E coating may be provided on an interior surface of one of the substrates, then the two substrates 2, 3 (including any low-E coating, not shown) may be brought together around edge seal material and spacers as discussed herein during the VIG formation process.
Referring to
Getter 32 absorbs and/or binds with certain residual impurities (e.g., undesirable gases such as CO2 and N2) that may remain and/or are present in the cavity 6 during and/or after evacuation. The getter 32 may be located in a getter container in the getter recess 14, or alternatively may be deposited or located directly on the substrate 2 in different example embodiments of this invention. Getter 32, for purposes of simplicity, is illustrated as-deposited in non-activated form. Getters are typically subdivided into two main classes: evaporable getters (EGs) and non-evaporable getters (NEGs). EGs often include one or more alkaline earth metal(s) calcium, strontium, and/or especially barium. NEGs often include titanium, zirconium, or alloys thereof with one or more metals selected amongst aluminum and metal(s) of the first transition row. Both getter types, EGs and NEGs, require activation by heating for their operation to remove from the getter surface various oxides, carbides, and/or nitrides that otherwise inhibit the gaseous species to be removed from being sorbed on the getter's surface. Because of their high reactivity toward atmospheric gases, getters are typically made and transported in inactive form and require a suitable activating (e.g., flashing) heat treatment once they are arranged in the space to be evacuated. The getter 32 in the
Getter 32 can be provided below the pump-out tube 8 and at least partially in getter recess 14 in the glass substrate 2 as shown in
In the
Upon heating, activation for an EG type getter 32 includes evaporation of the metal (e.g., barium) onto the inner surfaces of the VIG unit, including onto the vertical, rounded or tilted sidewalls of recess 14 and/or onto the inner major surfaces of substrates 2, 3, and possibly into part of tube 8. Barium evaporation can be carried out by heating the EG 32 in accordance with the
An EG type getter 32 may be made of any suitable material that functions as an evaporable getter. Such materials include, but are not limited to, compounds comprising an element(s) chosen from among calcium, strontium, and barium. Preferably such compounds are in the form to limit the reactivity of these elements to air. An example useful EU material for a getter is an intermetallic compound BaAl4, which further may be admixed with nickel powder and possibly small quantities of one or more of Al, Fe, Ti and/or their alloys. Other EG materials will be familiar to those of skill in the art. Activation causes the evaporated getter material to form in and/or adjacent the recess 14, with evaporated getter material being the getter material that is present (e.g., present in/on one or more of: getter recess sidewall(s), getter recess, interior major surface(s) of one or both substrates proximate the getter recess, and/or pump-out tube recess and/or tube itself) following activation and/or flashing of getter that included EG type material.
Non-evaporable getter (NEG) material can also be used for getter 32 in
This invention is not limited to activating the getter 32 by a laser beam aimed through the pump-out tube as shown in
When the getter activation is performed in parallel to the evacuation (e.g., pump-out) process, the activation of the getter 32 (whether by laser, induction or microwave heating) can be sequenced so that the getter is not significantly further poisoned by residual gases in the cavity 6, When gradually heated, the technique may be designed so that the getter 32 does not exceed the temperature at which it begins to sorp (which temperature depends on the getter composition) during evacuation (e.g., pump-out) before the pressure drops to or below about 1×10-2 to 1×10-3 mbar. When shock heating is used to produce cracks in a getter including NEG material, the pressure in the cavity 6 should be close to the minimum pressure achieved during evacuation (e.g., pump-out), such as less than or equal to about 1×10-3 mbar, before the shock heating is designed to produce the cracks.
Producing cracks in the getter 32 for the purpose of exposing reactive bulk material for gettering may be facilitated by incorporating high expansion material within the bulk of the getter in certain example embodiments. The high expansion material could be a gas, liquid, or high CTE solid. Liquids or solids with transitions to high expansion phases occurring above the highest processing temperature (e.g., frit firing) may be used.
In certain example embodiments of this invention, there is provided a method of making a vacuum insulated glass (VIG) window unit, the method comprising: having first and second substantially parallel glass substrates, a plurality of spacers and a seal provided between the first and second substrates, and a cavity to be evacuated to a pressure less than atmospheric pressure located between the glass substrates, and a getter supported (directly or indirectly) by the first substrate; and directing a laser beam (focused, non-focused, or parallel) through a pump-out tube supported (directly or indirectly) by the second substrate so that the laser beam impinges upon the getter and activates the getter.
In the method of the immediately preceding paragraph, said directing the laser beam through the pump-out tube to activate the getter may be performed during and/or substantially at an end of an evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In the method of any of the preceding two paragraphs, said directing the laser beam through the pump-out tube to activate the getter may be performed at least during an evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In the method of any of the preceding three paragraphs, said directing the laser beam through the pump-out tube to activate the getter may be performed at least substantially at an end of an evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In the method of any of the preceding four paragraphs, said directing the laser beam through the pump-out tube to activate the getter may be performed so that the getter does not exceed a temperature at which it begins to absorb undesirable gas(es) before pressure in the cavity drops to or below about 1×10-2 to 1×10-3 mbar during an evacuation process.
In the method of any of the preceding five paragraphs, said directing the laser beam through the pump-out tube to activate the getter may be performed after an evacuation process causes pressure in the cavity to reach less than or equal to about 1×10-3 mbar.
In the method of any of the preceding six paragraphs, the getter may be located in a recess defined in the first substrate.
In the method of any of the preceding seven paragraphs, the getter may be located directly below the pump-out tube when the VIG unit is viewed in cross section.
In the method of any of the preceding eight paragraphs, the getter may comprise barium or including NEG material.
In the method of any of the preceding nine paragraphs, the VIG window unit may have a visible transmission of at least about 50%.
In certain example embodiments of this invention (e.g., see
In the method of the immediately preceding paragraph, said activating the getter may be performed at least during the evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In the method of any of the preceding two paragraphs, said activating the getter may be performed at least substantially at an end of the evacuation process in which the cavity is evacuated to a pressure less than atmospheric pressure.
In the method of any of the preceding three paragraphs, said activating may comprise directing a laser beam through a pump-out tube supported by the second substrate so that the laser beam impinges upon the getter and activates the getter, where the getter is supported by the first substrate.
In the method of any of the preceding four paragraphs, said activating may comprise directing a laser beam at the getter in order to at least help activate the getter.
In the method of any of the preceding five paragraphs, said activating may comprise emitting microwave radiation from a microwave source toward the getter in order to at least help activate the getter.
In the method of any of the preceding six paragraphs, said activating may comprise emitting RF radiation from at least a coil toward the getter in order to at least help activate the getter.
In the method of any of the preceding seven paragraphs, said activating may be performed so that the getter does not exceed the temperature at which it begins to sorp before pressure in the cavity drops to or below about 1×10-2 to 1×10-3 mbar during an evacuation process.
In the method of any of the preceding eight paragraphs, said activating may be performed after an evacuation process causes pressure in the cavity to reach less than or equal to about 1×10-3 mbar.
In the method of any of the preceding nine paragraphs, the getter may be located directly below a pump-out tube when the VIG unit is viewed in cross section.
In the method of any of the preceding ten paragraphs, the VIG window unit may have a visible transmission of at least about 50%.
While certain example embodiments have been described and disclosed herein, it will be understood that the embodiments described herein are intended to be illustrative, not limiting, and that those skilled in the art will understand that various modifications may be made without departing from the true spirit and full scope of the claims appended hereto.
