Photochromic window with capillary flow control

Claim 2

A window assembly comprising first and second closely spaced panes, a source of liquid above the space between the panes, and means including a capillary flow passageway connecting the source of liquid with the top of the space between the panes and effective to maintain essentially constant the gravity flow of liquid to said space when the latter is filled with said liquid and the source and said passageway are at an essentially constant temperature, and a normally open outlet for free liquid flow from the bottom of said space, said passageway constituting the greatest resistance to liquid flow from said source through said space to said outlet, whereby said constant flow is independent of the temperature and viscosity of the liquid in said space.

Claim 3

The assembly of claim 1, said source of liquid comprising a first reservoir, a filling opening in said first reservoir, a second reservoir below the space between the panes, and a conduit in communication at its respective ends with saId outlet and said second reservoir.

Claim 4

The assembly of claim 2, said panes being constructed and arranged to form a canal therebetween at and extending along the top edge of said space and from which the liquid may flow to said space, said capillary passageway being in communication with said canal.

Claim 5

The assembly of claim 3, said panes being spaced a distance on the order of 0.05 mm, said passageway having an effective diameter of not more than 1 mm.

Claim 6

A photochromic window having spaced panes of pellucid material, means to flow photochromic liquid into and through the space between the panes by gravity, and including a first reservoir and means to control the flow of liquid from said first reservoir into the space between the panes, comprising a passageway of capillary size in transverse section, said passageway constituting the greatest restriction to flow in the flow path and said reservoir and passageway being installed in a zone subject to only relatively small changes in temperature which do not appreciably affect the viscosity of the liquid and size of the passageway.

Claim 7

A photochromic window having spaced panes of pellucid material, means to flow photochromic liquid into and through the space between the panes by gravity, and including a first reservoir and means to control the flow of liquid from said first reservoir into the space between the panes, comprising a passageway of capillary size in transverse section, said passageway constituting the greatest restriction to flow in the flow path and said reservoir and passageway being installed in a zone subject to only relatively small changes in temperature which do not appreciably affect the viscosity of the liquid and size of the passageway.

Claim 8

Apparatus comprising an on-edge window assembly including two spaced panes joined together at their peripheral margins to form a thin space therebetween, a sump reservoir below said space, conduit means connecting the bottom of said space to the top of said sump reservoir, a supply reservoir above said space, conduit means including a capillary flow passage connecting the bottom of the supply reservoir to the top of said space, said supply reservoir and flow passage being installed in a zone which is normally free from material temperature changes during use, said space, conduit means and reservoirs constituting a sealed system, and a liquid filling the space between the panes and at least partially filling the supply reservoir, whereby there is a constant flow of said liquid from the supply reservoir to the sump reservoir through the capillary flow passage and said space, the resistance to the flow of said liquid through said passage being substantially greater than that at any other part of the flow path.

Claim 9

Apparatus comprising an on-edge window assembly including two spaced panes joined together at their peripheral margins to form a thin space therebetween, a sump reservoir below said space, conduit means connecting the bottom of said space to the top of said sump reservoir, a supply reservoir above said space, conduit means including a capillary flow passage connecting the bottom of the supply reservoir to the top of said space, said supply reservoir and flow passage being installed in a zone which is normally free from material temperature changes during use, said space, conduit means and reservoirs constituting a sealed system, and a liquid filling the space between the panes and at least partially filling the supply reservoir, whereby there is a constant flow of said liquid from the supply reservoir to the sump reservoir through the capillary flow passage and said space, the resistance to the flow of said liquid through said passage being substantially greater than that at any other part of the flow path.

Claim 10

Apparatus as defined in claim 6 comprising conduit means connecting the tops of said reservoirs above the liquid level therein whereby the gaseous pressure in said sealed system is equalized.

Claim 11

Apparatus as defined in claim 6 comprising conduit means by-passing said flow passage and connecting the supply reservoir to the top of said space.

Claim 12

Apparatus as defined in claim 8 comprising valve means for selectively opening and closing said last-named conduit means.

Claim 13

Apparatus as defined in claim 6 comprising a normally deflated flexible bag connected to the air space in the sealed system.

Claim 14

Apparatus as defined in claim 6 comprising transverse channels between the panes at the upper and lower ends of said space connecting the latter with said conduit means.