Apparatus and method for a focus position lock device for a projection television lens assembly

A focus position lock device for use in a projection television lens system, said projection television lens system comprising:

• a lens cell having a plurality of optical lens units mounted therein;
• and a focus mount having a slot therein, said lens cell being telescopically mounted within said focus mount, said focus position lock device further comprising:
• a sleeve projecting radially outward from and integral with said lens cell, said sleeve having a rim at an end distal to said lens cell, said rim further including two grooves on an upper surface, each of said grooves being spaced approximately 180° apart on said rim of said sleeve, said sleeve being aligned below said slot of said focus mount;
• a spacer comprising a cylindrical body with a radial flange at one end, said cylindrical body of said spacer being disposed within said sleeve with the bottom of said cylindrical body being spaced apart from said sleeve, said spacer having an opening traversing said spacer from an upper surface of said flange through said cylindrical body, said opening being surrounded by an upwardly raised rim extending from said upper surface of said flange, said raised rim of said spacer being securely held within said slot of said focus mount, said flange further comprising two ridges extending downward from a lower surface of said flange, each of said ridges being spaced approximately 180° apart on said flange, each of said ridges being received within each of said grooves of said sleeve;
• a bolt coupled to said opening of said raised rim of said spacer, one end of said bolt being disposed and secured within said cylindrical body of said spacer and an opposite end of said bolt extending outward through said slot of said focus mount;
• and
• a nut secured onto said bolt.

A projection television lens system comprising:

• three cathode ray tubes;
• a screen;
• a lens assembly coupled to each of said cathode ray tubes for projecting light from each of said cathode ray tubes onto said screen to form an image, said lens assembly further comprising:
• a focus mount having a first slot;
• a lens cell having a plurality of optical lens units mounted therein, said lens cell being telescopically mounted within said focus mount;
• and
• a first focus position lock device for locking the focus position of said optical lens units, said first focus position lock device further comprising:
• a first sleeve projecting radially outward from and being integral with said lens cell, said first sleeve having a rim at an end distal to said lens cell, said rim having two grooves on an upper surface, each of said grooves being spaced approximately 180° apart on said rim of said first sleeve, each of said grooves being aligned to define a groove axis line that is parallel to the central axis line passing through the core of said lens cell, said first sleeve being aligned below said first slot of said focus mount;
• a first spacer comprising a cylindrical body with a radial flange at one end, said cylindrical body of said first spacer being disposed within said first sleeve, the bottom of said cylindrical body being spaced apart from said sleeve, said first spacer having an upwardly raised rim extending from an upper surface of said flange, said first spacer having an opening traversing said first spacer from said raised rim through said cylindrical body, said raised rim of said first spacer being adapted to securely fit into said first slot of said focus mount, said flange further comprising two ridges extending downward from a lower surface of said flange, each of said ridges being spaced approximately 180° apart on said flange, each of said ridges being received within each of said grooves of said first sleeve;
• a first bolt coupled to said opening of said raised rim of said first spacer, one end of said first bolt being disposed and secured within said cylindrical body of said first spacer and an opposite end of said first bolt extending outward through said first slot of said focus mount;
• and
• a first nut secured onto said first bolt, said first nut being adapted to lock the focus position of said lens cell of said projection television lens system.

A method of locking a focus position in a projection television lens assembly, comprising a lens cell having a plurality of optical lens units mounted therein and a focus mount, said lens cell being telescopically mounted within said focus mount, said method comprising the steps of:

• providing said lens cell with a first sleeve that projects radially outward from and is integral with said lens cell, said first sleeve having a first spacer secured therein;
• establishing a focus position for said projection television lens assembly;
• and
• locking said focus position of said projection television lens assembly such that tilting of said lens cell within said focus mount is prevented while locking.

A method of preventing tilting of a lens cell telescopically mounted within a focus mount when locking a focus position of a projection television lens assembly, said method comprising the steps of:

• interposing a spacer between said lens cell and said focus mount, said spacer lying along a transverse axis relative to a central longitudinal axis of said lens cell;
• coupling said spacer to said lens cell in a manner which prevents rotation of said spacer about said transverse axis and allows radial movement of said spacer along said transverse axis;
• establishing a focus position for said projection television lens assembly;
• coupling a fastener to said spacer;
• and
• using said fastener to move said spacer radially along said transverse axis and into frictional engagement with an interior surface of said focus mount thereby locking said focus position of said projection television lens assembly.