Abstract: A filter media and a pleated filter with a first layer of filtration media, a layer of support material and a second layer of filtration media on the opposite side of the support material as the first layer of filter media. All three layers are laminated together and pleated. The support material provides the required stiffness and rigidity for the pleating process. The physical characteristics of the upstream layer of filtration media are contemplated to be different than the characteristics of the downstream layer of filtration media.

Abstract: A collapsible HVAC filter that includes a pleated filter media pack with ends that attach to ends of a planar filter frame member. The structure collapses by folding the filter frame member along score lines and compressing the pleated filter media while the media and frame member are attached. The collapsed components occupy little space relative to the expanded filter, and can be expanded to form a completed filter with little effort required by the end user. Most of the filter media is collapsed in a generally U-shaped channel formed from the folded filter frame member.

Abstract: An air filter and frame that cooperate to require alignment of the filter in a desired orientation in order for insertion to occur. At least one edge of the filter is offset from a right angle relative to other edges and the faces of the filter, and an obstruction is formed in the frame so that the filter can be inserted into the frame in only the desired orientation. Preferably two opposing edges of the frame are angled, and obstructions, such as small rails, are mounted in opposing sidewalls of the frame.

Abstract: An air filter including a plurality of air-pervious sheets of electret filtration material. The sheets are disposed in a parallel relationship to form a stack of sheets, and each of the sheets has a plurality of slits formed therein for subsequent expanding to form openings. The stack is connected together at opposing ends, such as by bonding. The sheets can be pleated by mounting in a frame. The frame has opposing ends to which the opposing ends of the stack are mounted. The filter media initially has no frame and is not pleated, but is in a flat pad form that is expanded to be installed into a frame. The frame is then mounted in an appliance, such as a room air filter. When the filter is inserted into the filter housing it is expanded and can take a pleated form.

Abstract: An air filter and frame that cooperate to require alignment of the filter in a desired orientation in order for insertion to occur. At least one edge of the filter is offset from a right angle relative to other edges and the faces of the filter, and an obstruction is formed in the frame so that the filter can be inserted into the frame in only the desired orientation. Preferably two opposing edges of the frame are angled, and obstructions, such as small rails, are mounted in opposing sidewalls of the frame.

Abstract: An air filter including a plurality of air-pervious sheets of electret filtration material. The sheets are disposed in a parallel relationship to form a stack of sheets, and each of the sheets has a plurality of slits formed therein for subsequent expanding to form openings. The stack is connected together at opposing ends, such as by bonding. The sheets can be pleated by mounting in a frame. The frame has opposing ends to which the opposing ends of the stack are mounted. The filter media initially has no frame and is not pleated, but is in a flat pad form that is expanded to be installed into a frame. The frame is then mounted in an appliance, such as a room air filter. When the filter is inserted into the filter housing it is expanded and can take a pleated form.

Abstract: An air filter including a plurality of air-pervious sheets of electret filtration material. The sheets are disposed in a parallel relationship to form a stack of sheets, and each of the sheets has a plurality of slits formed therein for subsequent expanding to form openings. The stack is connected together at opposing ends, such as by bonding. The sheets can be pleated by mounting in a frame. The frame has opposing ends to which the opposing ends of the stack are mounted. The filter media initially has no frame and is not pleated, but is in a flat pad form that is expanded to be installed into a frame. The frame is then mounted in an appliance, such as a room air filter. When the filter is inserted into the filter housing it is expanded and can take a pleated form.

Abstract: A filter media and a pleated filter with a first layer of filtration media, a layer of support material and a second layer of filtration media on the opposite side of the support material as the first layer of filter media. All three layers are laminated together and pleated. The support material provides the required stiffness and rigidity for the pleating process. The physical characteristics of the upstream layer of filtration media are contemplated to be different than the characteristics of the downstream layer of filtration media.

Abstract: An air filter including a plurality of air-pervious sheets of electret filtration material. The sheets are disposed in a parallel relationship to form a stack of sheets, and each of the sheets has a plurality of slits formed therein for subsequent expanding to form openings. The stack is connected together at opposing ends, such as by bonding. The sheets can be pleated by mounting in a frame. The frame has opposing ends to which the opposing ends of the stack are mounted. The filter media initially has no frame and is not pleated, but is in a flat pad form that is expanded to be installed into a frame. The frame is then mounted in an appliance, such as a room air filter. When the filter is inserted into the filter housing it is expanded and can take a pleated form.