Device for locating a film transparency

Claim 2

For use in a projector, a device for locating in a reference position a film transparency having opposed first and second surfaces, said device comprising: means for supporting such a film transparency for movement relative to said reference position in a path generally perpendicular to the film transparency surfaces and with the second surface exposed to a reference pressure, said reference pressure producing a resultant force acting on the second surface; means for applying a fluid pressure to the first surface, which fluid pressure in cooperation with said reference pressure effects movement of the film transparency along said path, said fluid pressure applying means including means for producing a first pressure having a magnitude greater than said reference pressure and a second pressure having a magnitude less than said reference pressure, said first and said second pressures respectively producing first and second forces acting on the first surface; and means for varying the respective magnitudes of said first and said second pressures relative to each other as a function of the position of the supported film transparency along said path so that said first and second forces produce a resultant force acting on the first surface equal to said resultant force acting on the second surface when the film transparency is moved into said reference position.

Claim 3

A device as defined in claim 1 wherein said pressure varying means includes means for simultaneously increasing said first force over a first portion of the first surface and for decreasing said second force over a second portion of the first surface upon movement of the film transparency from said reference position in the direction faced by the first surface such that the fluid pressure over the first surface exerts a total force thereon greater than said resultant force exerted over the second surface, whereby the film transparency is moved toward said reference position by the force differential.

Claim 4

A device as defined in claim 1 wherein said pressure varying means includes means for simultaneously decreasing said first force over a first portion of the first surface and for increasing said second force over a second portion of the first surface upon movement of the film transparency from said reference position in the direction faced by the second surface of the film transparency such that the fluid pressure over the first surface exerts a total force thereon less than said resultant force exerted on the second surface, whereby the film transparency is moved toward said reference position by the force differential.

Claim 5

A device as defined in claim 3 wherein said pressure varying means includes means for directing fluid toward the first portion of the first surface and for causing the fluid to flow radially outward across the second portion of the first surface.

Claim 6

For use in a projector, a device for locating in a reference position a film transparency having opposed first and second surfaces, said device comprising: means for supporting such a transparency for movement relative to said reference position in a path generally perpendicular to the film transparency surfaces and with the second surface exposed to air at atmospheric pressure; means cooperable with the first surface of the transparency for defining an air chamber to subject the first surface to the influence of a variable air pressure, said chamber having a first portion positioned to receive air under pressure greater than atmospheric and a second portion communicating with said first portion and positioned to receive air flowing out of said first chamber portion, said second chamber portion being shaped to cause such air flowing out of said first chamber portion to increase in speed such that the air pressure in said second chamber portion will be below atmospheric while the air pressure in said first chamber portion is above atmospheric; and means for applying air to said first chamber portion under a pressure such that the resultant force of the pressures in said first and second chamber portions against the first surface is equal to the resultant force of the atmospheric pressure against the second surface when the transparency is in the reference position and such that a differential resultant force exists urging the transparency toward the reference position when the transparency is away from the reference position.

Claim 7

For use in a projector, a device for locating in a reference position a film transparency having opposed first and second surfaces, said device comprising: means for supporting such a transparency for movement relative to said reference position in a path generally perpendicular to the film transparency surfaces and with the second surface exposed to air at atmospheric pressure; means cooperable with the first surface of the transparency for defining an air chamber to subject the first surface to the influence of a variable air pressure, said chamber having a first portion positioned to receive air under pressure greater than atmospheric and a second portion communicating with said first portion and positioned to receive air flowing out of said first chamber portion, said second chamber portion being shaped to cause such air flowing out of said first chamber portion to increase in speed such that the air pressure in said second chamber portion will be below atmospheric while the air pressure in said first chamber portion is above atmospheric; and means for applying air to said first chamber portion under a pressure such that the resultant force of the pressures in said first and second chamber portions against the first surface is equal to the resultant force of the atmospheric pressure against the second surface when the transparency is in the reference position and such that a differential resultant force exists urging the transparency toward the reference position when the transparency is away from the reference position.

Claim 8

For use in a projectoR having an optical axis, means for directing a beam of light along the optical axis, and projecting means for projecting such light onto a viewing surface, a device for locating in a reference position along the optical axis an image bearing transparency having first and second surfaces, said device comprising: means for mounting the transparency to extend across a given cross-section of the light beam such that the light appearing within said given cross-section projects the image thereon through said projecting means onto the viewing surface, said transparency mounting means further including means for supporting such a film transparency to permit movement relative to said reference position along the optical axis with the second surface exposed to atmospheric pressure; a transparent member having an aperture located about said optical axis, said transparent member extending across said given cross-section of said projected light beam and being spaced along the optical axis relative to said transparency mounting means such that said transparent member is out of the depth of field of said projecting means; a source of fluid under pressure; means for directing fluid from said source through said aperture of said transparent member toward the first surface of the supported film transparency to create a first pressure, having a magnitude greater than atmospheric pressure, acting against a first portion of the first surface; and means for directing at least a portion of the fluid acting against the first portion of the first surface between said transparent member and a second portion of the first surface of the transparency to create a second pressure, having a magnitude less than atmospheric pressure, acting against the second portion of the first surface, whereby the resultant of said first and said second pressures produce a force equal to the force produced by said atmospheric pressure acting on the second surface when the film transparency is positioned at said reference position.

Claim 9

For use in a projectoR having an optical axis, means for directing a beam of light along the optical axis, and projecting means for projecting such light onto a viewing surface, a device for locating in a reference position along the optical axis an image bearing transparency having first and second surfaces, said device comprising: means for mounting the transparency to extend across a given cross-section of the light beam such that the light appearing within said given cross-section projects the image thereon through said projecting means onto the viewing surface, said transparency mounting means further including means for supporting such a film transparency to permit movement relative to said reference position along the optical axis with the second surface exposed to atmospheric pressure; a transparent member having an aperture located about said optical axis, said transparent member extending across said given cross-section of said projected light beam and being spaced along the optical axis relative to said transparency mounting means such that said transparent member is out of the depth of field of said projecting means; a source of fluid under pressure; means for directing fluid from said source through said aperture of said transparent member toward the first surface of the supported film transparency to create a first pressure, having a magnitude greater than atmospheric pressure, acting against a first portion of the first surface; and means for directing at least a portion of the fluid acting against the first portion of the first surface between said transparent member and a second portion of the first surface of the transparency to create a second pressure, having a magnitude less than atmospheric pressure, acting against the second portion of the first surface, whereby the resultant of said first and said second pressures produce a force equal to the force produced by said atmospheric pressure acting on the second surface when the film transparency is positioned at said reference position.

Claim 10

For use in a projector having an optical axis, means for projecting a beam of light along the optical axis, and projecting means for projecting such light onto a view-ing surface, a device for locating in a reference position along the optical axis an image bearing transparency having first and second surfaces, said device comprising: means for mounting the transparency to extend across at least a given portion of the light beam such that light defining said given portion of the beam causes the image on the transparency to be projected onto the viewing surface, said transparency mounting means further including means for supporting such a film transparency for movement in either direction along the optical axis relative to the reference position with the second surface exposed to atmospheric pressure; a transparent wall spaced along the optical axis from said reference position, said wall having (1) a first area defining with a first portion of the supported transparency a first chamber portion and (2) a second area radially outwardly from said first area defining with a second portion of the supported transparency a second chamber portion surrounding, contiguous with and open to said first chamber portion, said transparent wall extending across said given portion of the light beam and being spaced along the optical axis relative to said transparency mounting means such that said transparent wall is out of the depth of field of said projecting means; means for admitting fluid under pressure into said first chamber portion, said fluid admitting means including means for creating within said first chamber portion a pressure having a magnitude greater than atmospheric pressure and for creating within said second chamber portion a pressure having a magnitude less than atmospheric pressure, said pressure in said first chamber portion producing a first force acting on the first portion of the transparency and said pressure in said second chamber portion producing a secOnd force acting on the second portion of the transparency, the magnitudes of said first and second forces being related to the position of the transparency relative to the reference position whereby the resultant of said forces moves the transparency to the reference position.

Claim 11

For use in a projector having an optical axis, means for projecting a beam of light along the optical axis, and projecting means for projecting such light onto a view-ing surface, a device for locating in a reference position along the optical axis an image bearing transparency having first and second surfaces, said device comprising: means for mounting the transparency to extend across at least a given portion of the light beam such that light defining said given portion of the beam causes the image on the transparency to be projected onto the viewing surface, said transparency mounting means further including means for supporting such a film transparency for movement in either direction along the optical axis relative to the reference position with the second surface exposed to atmospheric pressure; a transparent wall spaced along the optical axis from said reference position, said wall having (1) a first area defining with a first portion of the supported transparency a first chamber portion and (2) a second area radially outwardly from said first area defining with a second portion of the supported transparency a second chamber portion surrounding, contiguous with and open to said first chamber portion, said transparent wall extending across said given portion of the light beam and being spaced along the optical axis relative to said transparency mounting means such that said transparent wall is out of the depth of field of said projecting means; means for admitting fluid under pressure into said first chamber portion, said fluid admitting means including means for creating within said first chamber portion a pressure having a magnitude greater than atmospheric pressure and for creating within said second chamber portion a pressure having a magnitude less than atmospheric pressure, said pressure in said first chamber portion producing a first force acting on the first portion of the transparency and said pressure in said second chamber portion producing a secOnd force acting on the second portion of the transparency, the magnitudes of said first and second forces being related to the position of the transparency relative to the reference position whereby the resultant of said forces moves the transparency to the reference position.

Claim 12

A device as defined in claim 7 wherein said means for admitting fluid into said first chamber portion comprises: an opening defined by said wall in said first area; a source of fluid under pressure; and means interconnecting said opening to said source.

Claim 13

For use in a projector having an optical axis, a device for locating in a reference position along an optical axis a film transparency having first and second surfaces, said device comprising: means for supporting such a film transparency for movement in either direction relative to said reference position along the optical axis with the second surface exposed to atmospheric pressure; a transparent wall spaced from said transparency supporting means so as to define a passage between said wall and the first surface of the transparency, said wall having a first portion in the shape of a hollow frustum opening toward the transparency and a second portion contiguous with and surrounding said first portion; a source of fluid pressure; and means for directing fluid from said source into said passage so as to create two individually distinct zones of pressure therein consisting of a zone of relatively high pressure having a magnitude greater than atmospheric pressure between said first portion of said wall and the transparency and a zone of relatively low pressure having a magnitude less than atmospheric pressure between said second portion and the transparency.

Claim 14

For use in a projector having an optical axis, a device for locating in a reference position along an optical axis a film transparency having first and second surfaces, said device comprising: means for supporting such a film transparency for movement in either direction relative to said reference position along the optical axis with the second surface exposed to atmospheric pressure; a transparent wall spaced from said transparency supporting means so as to define a passage between said wall and the first surface of the transparency, said wall having a first portion in the shape of a hollow frustum opening toward the transparency and a second portion contiguous with and surrounding said first portion; a source of fluid pressure; and means for directing fluid from said source into said passage so as to create two individually distinct zones of pressure therein consisting of a zone of relatively high pressure having a magnitude greater than atmospheric pressure between said first portion of said wall and the transparency and a zone of relatively low pressure having a magnitude less than atmospheric pressure between said second portion and the transparency.