Patent Description:
Glass panel units with excellent thermal insulation properties have been proposed in the known art. For example, in a multi-pane glazing disclosed in Patent Literature <NUM>, a sealant is interposed between a pair of glass panes. In this state, the whole assembly is heated to a temperature higher than a melting temperature of the sealant, thereby bonding the pair of glass panes together with the sealant thus melted. In this manner, a hermetically sealed space (internal space) is created between the pair of glass panes and the sealant.

Next, a gas is exhausted from the hermetically sealed space with the temperature of a melting furnace kept lower than the melting temperature of the sealant, thus activating an adsorbent. Thereafter, the hermetically sealed space is sealed up with the evacuated state maintained by a so-called "tip off' technique, by which a tip portion of an exhaust pipe, protruding from one of the glass panes, is melted to close its exhaust port and thereby seal the internal space.

In the known multi-pane glazing, however, the exhaust port is conspicuous through the other glass pane with no exhaust ports, thus marring its appearance, which is a problem with the known multi-pane glazing.

In view of the foregoing background, it is therefore an object of the present disclosure to provide a glass panel unit and a glass window, both of which are designed to make the exhaust port much less conspicuous when viewed through the glass pane with no exhaust ports.

A glass panel unit according to an implementation of the present disclosure includes: a first panel including a glass pane; a second panel including another glass pane; a sealing portion; an exhaust port; and a printed portion. The second panel is arranged to face the first panel. The sealing portion is formed in a frame shape and hermetically bonds respective peripheral edge portions of the first and second panels to create an evacuated, hermetically sealed space between the first panel and the second panel. The exhaust port is provided for one panel selected from the group consisting of the first and second panels. The printed portion is provided for the other panel selected from the group consisting of the first and second panels. The printed portion is located in an area, facing the exhaust port, of one surface of the other panel. The one surface either faces toward, or faces away from, the hermetically sealed space.

A glass window according to another implementation of the present disclosure includes the glass panel unit described above, and a window frame into which peripheral edge portions of the glass panel unit are fitted.

A glass panel unit and glass window according to the present disclosure will be described with reference to the accompanying drawings. Note that on those drawings, respective constituent members of a glass panel unit are depicted only schematically. That is to say, the dimensions and shapes of those constituent members illustrated on the drawings are different from actual ones.

First of all, a glass panel unit according to a first embodiment may be used as a glass panel unit for refrigerator showcases, for example. However, this is only an exemplary use of the present disclosure and should not be construed as limiting. The respective constituent elements of the glass panel unit according to the first embodiment will be described with reference to <FIG>.

The glass panel unit according to the first embodiment includes a first panel <NUM>, a second panel <NUM>, a sealing portion <NUM>, a port sealing member <NUM>, and a printed portion <NUM>.

The first panel <NUM> and the second panel <NUM> are arranged to face each other with a narrow gap left between them. The first panel <NUM> and the second panel <NUM> are parallel to each other. Between the first panel <NUM> and the second panel <NUM>, arranged are the sealing portion <NUM>, a plurality of (multiple) pillars <NUM>, and a gas adsorbent <NUM>.

The first panel <NUM> includes a glass pane <NUM> and a low emissivity film <NUM> (see <FIG>) stacked on the glass pane <NUM>. The low emissivity film <NUM> is a film containing a metal with low emissivity such as silver and has the capability of reducing the transfer of heat due to heat radiation. The low emissivity film <NUM> is formed on one surface, facing toward a hermetically sealed space <NUM>, of the glass pane <NUM>. In the first embodiment, the low emissivity film <NUM> is implemented as a so-called "low-E film. " The size of the glass pane <NUM> determines the size of the first panel <NUM>. In the first embodiment, the glass pane <NUM> has a rectangular shape in a front view.

The second panel <NUM> includes a glass pane <NUM>. The second panel <NUM> is arranged to face the first panel <NUM>. The size of the glass pane <NUM> determines the size of the second panel <NUM>. In the first embodiment, the glass pane <NUM> has a rectangular shape in a front view.

The size and shape of the glass pane <NUM> in a front view (i.e., the size and shape of the surface of the glass pane <NUM> as viewed perpendicularly to the surface of the glass pane <NUM>) are the same as the size and shape of the glass pane <NUM> in a front view.

The glass pane <NUM> and the glass pane <NUM> may be configured as any of various types of glass panes made of soda lime glass, high strain point glass, chemically tempered glass, alkali-free glass, quartz glass, Neoceram, thermally tempered glass, or any other suitable glass.

Most of a counter surface <NUM>, facing the second panel <NUM>, of the first panel <NUM> (i.e., a surface facing toward the hermetically sealed space <NUM> as will be described later) is constituted of the surface of the low emissivity film <NUM>. Most of a counter surface <NUM>, facing the first panel <NUM>, of the second panel <NUM> (i.e., another surface facing toward the hermetically sealed space <NUM>) is constituted of the surface of the second glass pane <NUM>. Note that in an area where the printed portion <NUM> is provided, that area is constituted of the surface of the printed portion <NUM>.

The sealing portion <NUM> is formed in a frame shape and may be made of a material having a predetermined melting point (softening point) (such as glass frit with a low melting point in the first embodiment). The melting point (softening point) of the sealing portion <NUM> may be <NUM> in the first embodiment but is not limited to any particular value. The sealing portion <NUM> is located between the first panel <NUM> and the second panel <NUM> and is hermetically bonded to respective peripheral edge portions of the first and second panels <NUM> and <NUM>. In other words, the respective peripheral edge portions of the first and second panels <NUM> and <NUM> are hermetically bonded together via the sealing portion <NUM>.

The plurality of pillars <NUM> are dispersed so as to be spaced apart from each other. Each of the pillars <NUM> is arranged in contact with both of the respective counter surfaces <NUM> and <NUM> of the first and second panels <NUM> and <NUM>.

The plurality of pillars <NUM> are arranged to be surrounded with the sealing portion <NUM> in the frame shape. The plurality of pillars <NUM> has the capability of keeping a predetermined gap distance between the first and second panels <NUM> and <NUM>. The plurality of pillars <NUM> is suitably made of a resin such as polyimide either entirely or only partially.

The gas adsorbent <NUM> is provided on one surface, facing toward the hermetically sealed space <NUM>, of either the first panel <NUM> or the second panel <NUM>. In the first embodiment, the gas adsorbent <NUM> is provided on one surface, facing toward the hermetically sealed space <NUM>, of the first panel <NUM>.

The glass panel unit according to the first embodiment has an exhaust port <NUM>. The exhaust port <NUM> is provided for one panel selected from the first panel <NUM> and the second panel <NUM>. In the first embodiment, the exhaust port <NUM> is provided for the first panel <NUM>, out of the first panel <NUM> and the second panel <NUM>. The port sealing member <NUM> is made of a material having a predetermined melting point (softening point) (such as a glass frit according to the first embodiment). The melting point (softening point) of the port sealing member <NUM> may be <NUM> in the first embodiment but is not limited to any particular value. The exhaust port <NUM> is hermetically sealed with the port sealing member <NUM>. The exhaust port <NUM> will be used to exhaust a gas in a process step (i.e., an evacuation step to be described later) during the manufacturing process of the glass panel unit. The exhaust port <NUM> penetrates through the first panel <NUM> in a thickness direction D1. As used herein, the "thickness direction D1" is defined along the thickness of the entire glass panel unit, the thickness of the first panel <NUM>, and the thickness of the second panel <NUM>.

The hermetically sealed space <NUM>, surrounded with the first panel <NUM>, the second panel <NUM>, and the sealing portion <NUM>, is entirely sealed hermetically by closing the exhaust port <NUM>. The hermetically sealed space <NUM> may be a thermally insulated space, which has been evacuated to a degree of vacuum of <NUM> Pa or less, for example.

A plate <NUM> arranged inside the exhaust port <NUM> is a member that has been used in a process step (that is a sealing step to be described later) during the manufacturing process of the glass panel unit. Optionally, the exhaust port <NUM> may be further stuffed with a resin to cover the plate <NUM>.

As shown in <FIG>, the printed portion <NUM> is provided on the counter surface <NUM>, facing the exhaust port <NUM>, of the second panel <NUM>. The printed portion <NUM> is made of a material having a predetermined melting point (softening point) (such as a glass frit according to the first embodiment). The melting point (softening point) of the printed portion <NUM> is higher than the melting point of the sealing portion <NUM>. In the first embodiment, the melting point of the printed portion <NUM> is <NUM>, which is higher by <NUM> than <NUM> as the melting point of the sealing portion <NUM> and the port sealing member <NUM>. Furthermore, the melting point of the printed portion <NUM> is more suitably a temperature higher than <NUM>. Note that the respective melting points of the printed portion <NUM>, the sealing portion <NUM>, and the port sealing member <NUM> are not limited to any specific numerical values. Alternatively, the printed portion <NUM> may also be made of a material including a ceramic and does not have to be a glass frit. If the printed portion <NUM> is made of a material including a ceramic, then the melting point of the printed portion <NUM> is higher than the melting point of the sealing portion <NUM> made of a glass frit. In addition, making the printed portion <NUM> of such a material including a ceramic allows the sealing portion <NUM> made of the glass frit to adhere more easily to the printed portion <NUM> provided on the second panel <NUM>.

The printed portion <NUM> has opacity. In the first embodiment, the printed portion <NUM> includes a pigment such as a black pigment, which is dispersed in the entire printed portion <NUM>, thus rendering the printed portion <NUM> entirely opaque. However, this is only an example and should not be construed as limiting. Alternatively, the printed portion <NUM> may have opacity not entirely but mostly and may have a light-transmitting property locally. In that case, the shapes, ratio, and other parameters of the opaque part and the light-transmitting part of the printed portion <NUM> are not limited to particular ones.

In the first embodiment, the printed portion <NUM> has a predetermined width as measured inward from the edges in a front view of the second panel <NUM> and a predetermined length as measured along the edges of the second panel <NUM> as shown in <FIG>. In particular, in this first embodiment, the printed portion <NUM> forms the shape of a frame extending along the entire edges of the second panel <NUM>.

As shown in <FIG>, the exhaust port <NUM> and the gas adsorbent <NUM> are provided on the surface, facing toward the hermetically sealed space <NUM>, (i.e., the counter surface <NUM>) of a specific area of the first panel <NUM>. The specific area of the first panel <NUM> faces the printed portion <NUM>.

The printed portion <NUM> has opacity, and therefore, when the glass panel unit is viewed through the second panel <NUM>, the exhaust port <NUM>, the port sealing member <NUM>, the plate <NUM>, the sealing portion <NUM>, and the gas adsorbent <NUM> are hidden behind the printed portion <NUM> and invisible as shown in <FIG>. This reduces, when the glass panel unit is viewed through the second panel <NUM>, the chances of the conspicuous exhaust port <NUM>, port sealing member <NUM>, plate <NUM>, sealing portion <NUM>, and gas adsorbent <NUM> (e.g., the exhaust port <NUM>, among other things) marring the appearance of the glass panel unit.

Note that the port sealing member <NUM> and the gas adsorbent <NUM> are not always hidden behind the printed portion <NUM>. In addition, the printed portion <NUM> does not have to be formed in the frame shape. Rather, the shape, dimensions, number, and other parameters of the printed portion <NUM> are not limited to particular ones.

Next, a method for manufacturing the glass panel unit according to the first embodiment will be described.

A glass panel unit manufacturing method according to the first embodiment includes a providing step, a pillar placement step, a gas adsorbent arrangement step, a bonding step, an evacuation step, and a sealing step.

As shown in <FIG>, the providing step includes providing a first substrate <NUM> and a second substrate <NUM>. The first substrate <NUM> will constitute the first panel <NUM> of the glass panel unit when the first substrate <NUM> goes through respective manufacturing process steps. The second substrate <NUM> will constitute the second panel <NUM> of the glass panel unit when the second substrate <NUM> goes through respective manufacturing process steps.

The first substrate <NUM> includes a glass pane <NUM> and a low emissivity film <NUM> stacked on the glass pane <NUM> (see <FIG>). The second substrate <NUM> includes a glass pane <NUM>. In the following description, the glass pane <NUM> will be hereinafter referred to as a "first glass pane <NUM>" and the glass pane <NUM> will be hereinafter referred to as a "second glass pane <NUM>.

The first glass pane <NUM> will constitute the glass pane <NUM> of the first panel <NUM> to be obtained through the respective manufacturing process steps. Likewise, the low emissivity film <NUM> will constitute the low emissivity film <NUM> of the first panel <NUM>, and the second glass pane <NUM> will constitute the glass pane <NUM> of the second panel <NUM> when these members go through the respective manufacturing process steps.

The pillar placement step includes placing a plurality of (or multiple) pillars <NUM> on one surface (upper surface) along the thickness D1 of the second substrate <NUM> such that the pillars <NUM> are spaced apart from each other as shown in <FIG> and other drawings.

The gas adsorbent arrangement step includes arranging the gas adsorbent <NUM> on one surface (e.g., the lower surface) along the thickness D1 of the first substrate <NUM>. Specifically, a paste of the gas adsorbent <NUM>, containing a getter material, is applied onto the one surface along the thickness D1 of the first substrate <NUM>, using an applicator such as a dispenser.

The getter material contained in the gas adsorbent <NUM> may be a metallic getter material.

The pillar placement step and the gas adsorbent arrangement step do not have to be performed in this order but may also be performed in reverse order or even in parallel with each other.

The bonding step includes bonding the first substrate <NUM> and the second substrate <NUM> together with a sealant <NUM> in a frame shape. Specifically, the first substrate <NUM> and the second substrate <NUM> that have been loaded into a furnace with the sealant <NUM> and the plurality of pillars <NUM> interposed between them are heated in the furnace to a first temperature. The first temperature is set at a temperature higher than the melting point of the sealant <NUM> but lower than the melting point of the printed portion <NUM>, and may be <NUM>, for example. This heating step is conducted with the first substrate <NUM> and second substrate <NUM>, having the sealant <NUM> and the plurality of pillars <NUM> thereon, loaded into the furnace. Thereafter, the first substrate <NUM> and the second substrate <NUM> with the sealant <NUM> and the plurality of pillars <NUM> will be unloaded from the furnace.

Bonding the sealant <NUM> that has been melted through heating onto the first substrate <NUM> and the second substrate <NUM> creates an internal space <NUM> between the first and second substrates <NUM> and <NUM> and the sealing material <NUM> as shown in <FIG>. The plurality of pillars <NUM> and the gas adsorbent <NUM> are located in the internal space <NUM>. The sealant <NUM> will constitute the sealing portion <NUM> of the glass panel unit when the sealant <NUM> goes through the respective process steps.

In the bonding step, the first substrate <NUM> and the second substrate <NUM> are heated to no more than the first temperature that is lower than the melting point of the printed portion <NUM>, thus reducing the chances of the printed portion <NUM> being melted (softened).

The sealant <NUM> is applied, using an appropriate applicator, onto an outer peripheral portion of one surface along the thickness D1 of the second substrate <NUM> (second glass pane <NUM>) to form a frame pattern (see <FIG>).

The sealant <NUM> may be arranged before, after, or in parallel with, the pillar placement step. Likewise, the sealant <NUM> may also be arranged before, after, or in parallel with, the gas adsorbent arrangement step.

A work in progress <NUM> shown in <FIG> is obtained as a result of these manufacturing process steps. The work in progress <NUM> is an intermediate product obtained during the manufacturing process of the glass panel unit.

This work in progress <NUM> will be further subjected to an evacuation step and a sealing step.

The evacuation step and the sealing step are performed with the system shown in <FIG> and <FIG>. This system includes an evacuation mechanism <NUM>, a heating mechanism <NUM>, and a pressing mechanism <NUM>.

The evacuation mechanism <NUM> includes: an exhaust head <NUM> to be pressed against the work in progress <NUM>; and a connection pipe <NUM> connected to the exhaust head <NUM>. The evacuation mechanism <NUM> is configured to evacuate, through the exhaust port <NUM>, the internal space <NUM> created in the work in progress <NUM> and keep the internal space <NUM> evacuated.

The heating mechanism <NUM> is arranged opposite from the exhaust head <NUM> with respect to the work in progress <NUM> (see <FIG>). The heating mechanism <NUM> is configured to heat the port sealing member <NUM>, inserted into the exhaust port <NUM>, without making physical contact with the port sealing member <NUM>.

The heating mechanism <NUM> includes an irradiator <NUM>. The irradiator <NUM> is configured to irradiate the port sealing member <NUM>, inserted into the exhaust port <NUM>, with an infrared ray (e.g., a near-infrared ray) externally incident through the second substrate <NUM> (second glass pane <NUM>) and thereby heat the port sealing member <NUM>.

The pressing mechanism <NUM> is provided for the exhaust head <NUM>. The pressing mechanism <NUM> is configured to press, in a state where the internal space <NUM> is evacuated by the evacuation mechanism <NUM>, the port sealing member <NUM> inserted into the exhaust port <NUM> toward the second substrate <NUM>.

In the evacuation step, the port sealing member <NUM> and a plate <NUM>, each having a smaller diameter than the exhaust port <NUM>, are inserted into the exhaust port <NUM> of the work in progress <NUM> (see <FIG>). The port sealing member <NUM> is a solid sealing member made of a glass frit, for example. In this embodiment, the port sealing member <NUM> has a block shape. However, this is only an example and should not be construed as limiting. Alternatively, the port sealing member <NUM> may also have the shape of a cylinder with a vertically penetrating through hole. The plate <NUM> is arranged opposite from the second substrate <NUM> with respect to the port sealing member <NUM>.

The exhaust head <NUM> is brought into airtight contact with a region, surrounding the opening formed by the exhaust port <NUM>, of the first substrate <NUM>. At this time, the port sealing member <NUM> and the plate <NUM> are pressed elastically toward the second substrate <NUM>.

Exhausting the air in the exhaust head <NUM> in such a state by vacuum pumping through the connection pipe <NUM> (as indicated by the open arrow shown in <FIG>) allows the internal space <NUM> to be evacuated through the exhaust port <NUM>.

The sealing step includes sealing, using the heating mechanism <NUM> and the pressing mechanism <NUM>, the internal space <NUM> while keeping the internal space <NUM> evacuated.

Specifically, the sealing step includes heating and melting the port sealing member <NUM> using the heating mechanism <NUM> and pressing the port sealing member <NUM> against the second substrate <NUM> with the biasing force applied by the pressing mechanism <NUM> via the plate <NUM>. The port sealing member <NUM> is deformed in the internal space <NUM>.

This allows the exhaust port <NUM> to be closed with the port sealing member <NUM>, thus hermetically sealing the internal space <NUM> while keeping the internal space <NUM> evacuated. This internal space <NUM> will constitute the hermetically sealed space <NUM> of the glass panel unit when the internal space goes through the respective process steps.

Optionally, an activation step may be performed after that. The activation step includes locally heating the gas adsorbent <NUM>, arranged in the internal space <NUM> of the work in progress <NUM>, using a local heating mechanism, for example. The activation step is suitably carried out in parallel with the evacuation step. That is to say, while the internal space <NUM> is being evacuated using the exhaust head <NUM>, the gas adsorbent <NUM> is suitably heated locally by a contactless technique and activated in the evacuated internal space <NUM>. Alternatively, the gas adsorbent <NUM> may also be locally heated in the activation step after the sealing step has been performed. In that case, the internal space <NUM> that has been sealed in the evacuated state is irradiated with a laser beam and locally heated, thereby activating the gas adsorbent <NUM>.

The glass panel unit obtained by the manufacturing method described above has the hermetically sealed space <NUM> that has been sealed in the evacuated state and a sufficiently activated gas adsorbent <NUM> is housed in the hermetically sealed space <NUM>. This curbs a decline in the degree of vacuum of the hermetically sealed space <NUM>, thus maintaining the thermal insulation properties of the overall glass panel unit.

Optionally, the respective constituent elements of the glass panel unit described above and the respective manufacturing process steps of the glass panel unit may be modified in various manners as appropriate depending on a design choice or any other factor.

For example, a plurality of glass panel units may be obtained by further dividing, by a so-called "sectioning technique," the glass panel unit that has been formed by the same method as the one described above. In that case, partitions to divide the hermetically sealed space <NUM> into multiple spaces are provided between the first substrate <NUM> and the second substrate <NUM>.

When sectioning is performed, a section of the first substrate <NUM> that has been used during the manufacturing process will constitute the first panel <NUM> of the glass panel unit as a final product. Likewise, a section of the second substrate <NUM> that has been used during the manufacturing process will constitute the second panel <NUM> of the glass panel unit as a final product and a section of the sealant <NUM> will constitute the sealing portion <NUM> of the glass panel unit as a final product.

In the glass panel unit manufacturing method described above, the plurality of pillars <NUM> are placed on the one surface of the second substrate <NUM> in the pillar placement step. However, the plurality of pillars <NUM> may be placed on at least one of the first and second substrates <NUM>, <NUM>. That is to say, the plurality of pillars <NUM> may be placed on the first substrate <NUM> or may be distributed on the first substrate <NUM> and the second substrate <NUM>.

In the glass panel unit manufacturing method described above, the gas adsorbent <NUM> is irradiated, in the activation step, with a laser beam through the second substrate <NUM>. However, this is only an example and should not be construed as limiting. Rather, the gas adsorbent <NUM> may be irradiated with the laser beam through at least one of the first substrate <NUM> or the second substrate <NUM>. When the gas adsorbent <NUM> is irradiated with a laser beam through the first substrate <NUM>, the first substrate <NUM> suitably includes no low emissivity film <NUM>.

Next, a glass panel unit according to a second embodiment will be described with reference to <FIG>, and <FIG>. Note that the glass panel unit according to the second embodiment has mostly the same configuration as the glass panel unit according to the first embodiment. Thus, their common features will not be described all over again to avoid redundancies.

The glass panel unit according to the second embodiment uses annealed glass. The exhaust port <NUM> is isolated from the hermetically sealed space <NUM> by isolating a region surrounding the exhaust port <NUM> with a sealing portion <NUM>. The printed portion <NUM> is provided on the surface, facing toward the hermetically sealed space <NUM>, of a specific area of the second substrate <NUM>. The specific area of the second substrate <NUM> faces the sealing portion <NUM> and the exhaust port <NUM>. Since the exhaust port <NUM> is isolated from the hermetically sealed space <NUM> in this embodiment, the port sealing member <NUM> (and the plate <NUM>) may be eliminated.

In the second embodiment, the melting point (softening point) of the sealing portion <NUM> is <NUM> and the melting point (softening point) of the printed portion <NUM> is <NUM>, which is higher by <NUM> than <NUM> as the melting point of the sealing portion <NUM>.

The gas adsorbent <NUM> applied linearly is a non-metallic getter material with a porous structure. Examples of the non-metallic getter materials include zeolite-based, active carbon, and magnesium oxide getter materials. The zeolite-based getter materials include an ion exchanged zeolite. Examples of ion exchange materials include K, NH<NUM>, Ba, Sr, Na, Ca, Fe, Al, Mg, Li, H, and Cu. These are metallic getter materials.

The gas adsorbent <NUM> contains the non-metallic getter material with the porous structure, and therefore, is able to effectively adsorb gas molecules of a hydrocarbon based gas (such as CH<NUM> or C<NUM>H<NUM>) or an ammonia gas (NH<NUM>).

The glass panel unit according to the second embodiment achieves the same advantages as the glass panel unit according to the first embodiment does.

Next, a glass panel unit according to a third embodiment will be described with reference to <FIG>.

In the third embodiment, the glass panel unit is warped, which is a major difference from the first and second embodiments.

The glass panel unit is warped along the longitudinal axis thereof to have a predetermined curvature (or radius of curvature). On the other hand, the glass panel unit is not warped along the latitudinal axis thereof and its surface is straight.

The glass panel unit according to the third embodiment achieves the same advantages as the glass panel units according to the first and second embodiments. In addition, the third embodiment also facilitates arranging glass panel units onto a curved surface so that the respective surfaces of the glass panel units are continuous with each other.

<FIG> illustrate a glass panel unit according to a fourth embodiment. The glass panel unit according to the fourth embodiment includes not only the first panel <NUM> and second panel <NUM> of the glass panel unit shown in <FIG> but also a third panel <NUM> as well.

In the glass panel unit according to the fourth embodiment, the third panel <NUM> is laid on top of the first panel <NUM> to face the first panel <NUM>, and a hermetically sealed space <NUM> is created between the first panel <NUM> and the third panel <NUM>. Note that this arrangement of the third panel <NUM> is only an example. Alternatively, the third panel <NUM> may be laid on top of the second panel <NUM>, and a hermetically sealed space <NUM> may be created between the second panel <NUM> and the third panel <NUM>.

The third panel <NUM> includes at least a glass pane <NUM>. Optionally, the third panel <NUM> may have an appropriate coating.

Between the respective peripheral edge portions of the third panel <NUM> and first panel <NUM>, interposed are a frame-shaped spacer <NUM> with a hollow portion and a second sealing portion <NUM> formed in the shape of a frame covering the outer surfaces of the spacer <NUM>. The hollow portion of the spacer <NUM> is filled with a desiccant <NUM>. The space <NUM> is a space which is hermetically sealed by being surrounded with the third panel <NUM>, the first panel <NUM>, the second sealing portion <NUM>, and the spacer <NUM>.

The spacer <NUM> is made of a metal such as aluminum and has vent holes <NUM> provided through inner peripheral portions thereof. The hollow portion of the spacer <NUM> communicates with the space <NUM> through the vent holes <NUM>. The desiccant <NUM> may be a silica gel, for example. The second sealing portion <NUM> is suitably made of a highly airtight resin such as silicone resin or butyl rubber and hermetically bonded to the third panel <NUM> and the first panel <NUM>. The space <NUM> is filled with a dry gas (e.g., a dry rare gas such as argon gas or dry air).

A method for manufacturing the glass panel unit according to the fourth embodiment includes not only all of the process steps described above but also a second bonding step as well. The second bonding step includes hermetically bonding the first panel <NUM> and the third panel <NUM> (or the second panel <NUM> and the third panel <NUM>) together via the second sealing portion <NUM> with the spacer <NUM> interposed between them.

Next, a glass window according to a fifth embodiment will be described. The glass window according to the fifth embodiment includes the glass panel unit according to the first or fourth embodiment.

<FIG> illustrates a glass window including the glass panel unit according to the first embodiment. In this glass window, the peripheral edge portions of the glass panel unit shown in <FIG> are fitted into a frame <NUM>.

For example, the frame <NUM> may be a window frame. In that case, the glass window shown in <FIG> is a glass window including the glass panel unit according to the first embodiment. The glass window does not have to be an openable window but may also be a fixed window such as a show window.

Furthermore, examples of glass windows including the glass panel unit according to the first embodiment include not only glass windows but also other glazing for entrance doors and interior doors as well.

A method for manufacturing a glass window including the glass panel unit according to the first embodiment includes not only the respective process steps of the method for manufacturing the glass panel unit according to the first embodiment but also an assembling step as well. The assembling step includes fitting the rectangular frame <NUM> onto peripheral edge portions of the glass panel unit. A glass window manufactured through these process steps exhibits excellent thermal insulation properties.

In the glass window shown in <FIG>, the frame <NUM> is fitted onto the glass panel unit shown in <FIG>. However, the frame <NUM> is not necessarily fitted onto that glass panel unit. Alternatively, the frame <NUM> may also be fitted onto a glass panel unit obtained by the sectioning technique described above, for example.

Some embodiments of a glass panel unit and a glass window including the glass panel unit have been described. Note that the glass panel unit and glass window including the glass panel unit do not have to be implemented as shown in the accompanying drawings but may also be modified in various manners as appropriate depending on a design choice or any other factor.

Optionally, the printed portion <NUM> may also be provided for the surface, facing toward the hermetically sealed space <NUM>, of the one panel with the exhaust port <NUM> so as to be superposed on the exhaust port <NUM>. This renders the exhaust port <NUM> much less conspicuous even when the glass panel unit is viewed through the one panel with the exhaust port <NUM>. Even so, this further reduces the chances of the printed portion <NUM>, which is superposed on the gas adsorbent <NUM> or formed in a frame shape, marring the appearance of the glass panel unit.

Furthermore, in the first through fifth embodiments described above, the printed portion <NUM> is provided on one surface, facing toward the hermetically sealed space <NUM>, of a specific area of the other panel (e.g., the second panel <NUM> in the first through fifth embodiments), out of the first and second panels <NUM>, <NUM>, such that the specific area faces the exhaust port <NUM>. Alternatively, the printed portion <NUM> may also be provided on the opposite surface, facing away from the hermetically sealed space <NUM>, of the specific area of the other panel (e.g., the second panel <NUM>), out of the first and second panels <NUM>, <NUM>, such that the specific area faces the exhaust port <NUM>.

The invention is a glass panel unit as defined in claim <NUM>.

According to the invention, when the glass panel unit is viewed through the second panel (<NUM>), the exhaust port (<NUM>) is rendered much less conspicuous by being hidden behind the printed portion (<NUM>), thus reducing the chances of the conspicuous exhaust port (<NUM>) marring the appearance of the glass panel unit. Furthermore, the printed portion (<NUM>) looks like a frame, thus improving the appearance of the glass panel unit.

In an aspect, the sealing portion (<NUM>) and the printed portion (<NUM>) are made of two different materials, each of which has a predetermined melting point (softening point). The printed portion (<NUM>) has a higher melting point than the sealing portion (<NUM>).

This aspect reduces the chances of the printed portion (<NUM>) being melted while the respective peripheral edge portions of the first and second panels (<NUM>, <NUM>) are hermetically bonded together by melting the sealing portion (<NUM>).

In an aspect, the printed portion (<NUM>) is made of a material including a ceramic.

This aspect easily makes the melting point of the printed portion (<NUM>) higher than the melting point of the sealing portion (<NUM>).

In an aspect, the glass panel unit further includes a gas adsorbent (<NUM>) provided on one surface, facing toward the hermetically sealed space (<NUM>), of the one panel. The printed portion (<NUM>) has a predetermined width and a predetermined length. The predetermined width is measured inward from an edge in a front view of the other panel. The predetermined length is measured along the edge of the other panel. The exhaust port (<NUM>) and the gas adsorbent (<NUM>) are located in an area of the one surface, facing toward the hermetically sealed space (<NUM>), of the one panel. The area of the one surface of the one panel faces the printed portion (<NUM>) having the predetermined width and the predetermined length.

According to this aspect, not only the exhaust port (<NUM>) but also the gas adsorbent (<NUM>) are rendered much less conspicuous by being hidden behind the printed portion (<NUM>).

In an aspect, the glass panel unit further includes a low emissivity film (<NUM>) formed on the one surface, facing toward the hermetically sealed space (<NUM>), of the one panel.

This aspect reduces the transfer of heat through heat radiation caused by the glass panel unit.

In an aspect, the glass panel unit further includes a third panel (<NUM>) and a second sealing portion (<NUM>). The third panel (<NUM>) includes still another glass pane (<NUM>) and is arranged to face an arbitrary panel selected from the group consisting of the first and second panels (<NUM>, <NUM>). The second sealing portion (<NUM>) is formed in a frame shape and is hermetically bonded to the arbitrary panel and the third panel (<NUM>) to create another hermetically sealed space (<NUM>) between the arbitrary panel and the third panel (<NUM>).

This aspect provides a glass panel unit with further improved thermal insulation properties.

In an aspect, a glass window includes the glass panel unit according to any one of the first to seventh aspects; and a window frame (<NUM>) into which peripheral edge portions of the glass panel unit are fitted.

Claim 1:
A glass panel unit comprising:
a first panel (<NUM>) including a first glass pane (<NUM>);
a second panel (<NUM>) including a second glass pane (<NUM>) and arranged to face the first panel (<NUM>);
a sealing portion (<NUM>) formed in a frame shape and hermetically bonding respective peripheral edge portions of the first and second panels to create an evacuated, hermetically sealed space (<NUM>) between the first panel (<NUM>) and the second panel (<NUM>);
an exhaust port (<NUM>) provided for one panel selected from the group consisting of the first and second panels;
a plate (<NUM>) arranged inside the exhaust port (<NUM>), and
a printed portion (<NUM>) provided for the other panel selected from the group consisting of the first and second panels, the printed portion (<NUM>) being located in an area, facing the exhaust port (<NUM>), of one surface of the other panel, the one surface either facing toward, or facing away from, the hermetically sealed space (<NUM>),
the printed portion (<NUM>) being formed in a shape of a frame having a predetermined width as measured inward from edges in a front view of the other panel and extending along the edges in their entirety,
wherein, the printed portion (<NUM>) has opacity and when the glass panel unit is viewed through the other panel, the exhaust port (<NUM>), the plate (<NUM>) and the sealing portion (<NUM>) are hidden behind the printed portion (<NUM>) and are invisible.