Annular unframed pleated air filter

1 . A disposable, annular, unframed, pleated air filter, the air filter being configured to be in a compacted shape and being openable to a generally cylindrical, ready-for-use shape, and the air filter comprising:

a length of pleated air filter media comprising a longitudinal axis and comprising at least one joint so that the length of pleated air filter media is in a continuous annular shape, the pleated air filter media further comprising a transverse axis and exhibiting a pleat direction that is at least generally aligned with the transverse axis, and the pleated air filter media comprising an inward side with inward pleat tips and inward pleat valleys and an outward side with outward pleat tips and outward pleat valleys;

and,

at least one adhesive strand that is on the inward side of the length of pleated air filter media and is disposed on the inward pleat tips and penetrates at least partially into at least some of the inward pleat valleys;

wherein the length of pleated air filter media comprises a first preferred-bending zone and a second preferred-bending zone that is located diametrically opposite the first preferred-bending zone along the longitudinal axis of the pleated air filter media,

wherein the at least one adhesive strand comprises a first interruption at the first preferred-bending zone and comprises a second interruption at the second preferred-bending zone,

wherein at least one of the first and second preferred-bending zones is a jointed, non-integral preferred bending zone that is located at the at least one joint,

wherein the at least one joint is a single joint and wherein the first preferred-bending zone is an integral preferred-bending zone and the second preferred-bending zone is a jointed, non-integral preferred bending zone that is located at the single joint,

wherein the first, integral preferred-bending zone comprises a first, integral hinge-pleat with an outward pleat tip and with an inward pleat valley that is flanked by first and second flanking inward pleat tips,

wherein the first, integral hinge-pleat comprises first and second integral pleat-panels and wherein the first and second integral pleat-panels are non-separably bonded to each other in a bonding zone of each pleat-panel, so that the first, integral hinge-pleat is a bonded hinge-pleat,

and

wherein a non-integral tab is provided at the first, integral bonded hinge-pleat by way of being co-bonded to at least one of the first and second integral pleat-panels of the first, integral bonded hinge-pleat by the same bonding mechanism by which the first and second integral pleat-panels are bonded to each other to form the first, integral bonded hinge-pleat.

2 . The air filter of claim 1 wherein the first interruption of the at least one adhesive strand is configured so that the at least one adhesive strand does not extend beyond the first and second flanking inward pleat tips substantially into the inward pleat valley of the first, integral hinge-pleat.

3 . The air filter of claim 1 wherein when the air filter is in the generally cylindrical, ready-for-use shape, inward pleat valleys other than the inward pleat valley of the hinge-pleat exhibit, on average, a nominal inward valley angle; and, wherein the inward pleat valley of the bonded hinge-pleat exhibits an inward valley angle that is less than 20% of the nominal inward valley angle of the non-hinge-pleat inward pleat valleys.

4 . The air filter of claim 1 wherein the second, jointed, non-integral preferred-bending zone comprises a second, jointed, non-integral hinge-pleat with an outward pleat end and with an inward pleat valley that is flanked by first and second flanking inward pleat tips.

5 . The air filter of claim 4 wherein the second, jointed, non-integral hinge-pleat comprises at least two non-integral pleat-panels that are non-separably bonded to each other in a bonding zone of each pleat-panel to form the joint, so that the second, jointed, non-integral hinge-pleat is a bonded hinge-pleat.

6 . The air filter of claim 5 wherein the second, jointed, non-integral hinge-pleat comprises first and second integral pleat-panels and comprises third and fourth pleat-panels that are integral with each other but not with the first and second integral pleat-panels, and wherein at least the first and second integral pleat panels are non-separably bonded to each other, the third and fourth integral pleat panels are non-separably bonded to each other, and the first and third non-integral pleat-panels are non-separably bonded to each other, in a bonding zone of each pleat-panel to form the joint, so that the second, jointed, non-integral hinge-pleat is a many-layer hinge pleat.

7 . The air filter of claim 5 wherein a non-integral tab is provided at the second, jointed, non-integral bonded hinge-pleat by way of being co-bonded to at least one of the at least two non-integral pleat-panels by the same bonding mechanism by which the at least two non-integral pleat-panels are bonded to each other to form the second, jointed, non-integral bonded hinge-pleat.

8 . The air filter of claim 1 wherein sections of the at least one adhesive strand that penetrate at least partially into the inward pleat valleys are arranged in a bridging configuration such that in the portions of the inward pleat valleys into which the at least one adhesive strand penetrates, a section of the adhesive strand that is disposed on a first pleat-panel of the inward pleat valley is in contact with, and is non-separably bonded to, a section of the adhesive strand that is disposed on a second, opposing pleat-panel of the inward pleat valley, excepting in inward pleat valleys of the preferred-bending zones, where no such bridging configuration is present.

9 . The air filter of claim 8 wherein the sections of the at least one adhesive strand penetrate only partially into the inward pleat valleys so that the at least one adhesive strand exhibits a repeating intermittent pattern that is registered with the pleat pattern of the pleated air filter media, with the first and second interruptions of the at least one adhesive strand at the first preferred-bending zone and at the second preferred-bending zone, being superimposed on the repeating intermittent pattern of the at least one adhesive strand.

10 . The air filter of claim 1 wherein the at least one adhesive strand comprises at least four adhesive strands that are parallel to each other and are spaced apart from each other along the pleat direction of the pleated air filter media.

11 . The air filter of claim 1 wherein when the air filter is in the compacted shape it exhibits a volumetric compaction ratio of less than or equal to 30%, relative to when the air filter is in the opened, generally cylindrical, ready-for-use shape.

12 . The air filter of claim 1 wherein the air filter is in a flattened shape in which it exhibits a volumetric compaction ratio of less than 10%, relative to when the air filter is in the opened, generally cylindrical, ready-for-use shape.

13 . The air filter of claim 12 wherein the first preferred-bending zone comprises a first bonded hinge-pleat with an outward pleat tip and wherein first and second outward pleat valleys flank the first bonded hinge-pleat, and wherein when the air filter is in the flattened shape at least one of the first and second outward pleat valleys that flank the first bonded hinge-pleat exhibits an outward valley angle of at least 70 degrees.

14 . The air filter of claim 12 wherein the air filter is configured to be packaged in the flattened shape with there being no spacer present within an interior space defined within the air filter.

15 . A method of installing the air filter of claim 1 into a room air purifier, the air filter being in a flattened shape in which it exhibits a volumetric compaction ratio of less than 10% relative to when the air filter is in the opened, generally cylindrical, ready-for-use shape, and the method comprising:

opening the air filter from its flattened configuration into the opened, generally cylindrical, ready-for-use shape, and

slidably moving the opened air filter onto a generally cylindrical support mandrel of the air filter.

16 . A room air purifier with the air filter of claim 1 installed therein, the air filter being in the opened, generally cylindrical, ready-for-use shape and being disposed radially-outwardly on a mandrel of the room air purifier with the pleat direction of the air filter aligned with a vertical axis of the room air purifier.