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

• US 6,285,416 B1
• Filed: 05/06/1999
• Issued: 09/04/2001
• Est. Priority Date: 05/06/1999
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: Corning Precision Lens
• Inventors: Mitchell, John David, Okorocha, Livyn Obiajuru
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Tran, Trang U.
• Application Number:
  US09/306,471
• Time in Patent Office: 852 Days
• Field of Search: 348/745, 359/819, 359/820, 359/822, 359/823, 359/824, 359/826
• US Class Current: 348/745
• CPC Class Codes: G02B 7/04 with mechanism for focusing or varying magnification

Abstract

An apparatus and method for locking a focus position of a lens assembly without causing the lens cell to tilt, comprising: a spacer interposed between the lens cell and the focus mount. The spacer is received into a sleeve that is integral with the focus mount. The sleeve projects radially outward from the focus mount such that the spacer can be raised and lowered radially with respect to the focus mount. The spacer has a cylindrical body with a radial flange at one end. Moreover, the spacer has two ridges that extend downward from a lower surface of the flange, each of which is received into a corresponding groove on the sleeve, thus, preventing the spacer from rotating within the sleeve. The spacer also has an upwardly raised rim extending from an upper surface of the flange. The rim is slidably secured into a slot of the focus mount, which prevents lateral movement of the spacer. Further, a bolt is coupled to an opening within the spacer, such that one end of the bolt is disposed and secured within the spacer and the other end of the bolt extends radially outward through the slot of the focus mount. A nut is secured onto the bolt. After focusing the lens cell assembly, the nut is tightened onto the bolt in order to maintain focus of the lens cell assembly. The tightening of the nut brings an upper surface of the flange of the spacer into frictional engagement with an interior surface of the focus mount, which prevents the tilting of the lens cell within the focus mount, thus, maintaining a focus position of the lens assembly.

Claims

1. A projection television lens assembly, comprising:

a focus mount;

a lens cell having a longitudinal axis and a plurality of optical lens units mounted therein, said lens cell being telescopically mounted within said focus mount;

a spacer interposed between said lens cell and said focus mount, said spacer lying along a transverse axis relative to said longitudinal axis and being coupled to said lens cell such that, (i) when said spacer undergoes a rotational force about said transverse axis, a longitudinal force is not exerted on said lens cell and (ii) said spacer may be moved radially along said transverse axis without exerting a radial force on said lens cell; and

a fastener coupled to said spacer, said fastener operative to move said spacer radially for locking a focus position of said projection television lens assembly.

2. The projection television lens assembly of claim 1, wherein said spacer is received into a sleeve, said sleeve projecting radially from and being integral with said lens cell, said 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.

3. The projection television lens assembly of claim 2, wherein said spacer further comprises a cylindrical body with a radial flange at one end, said cylindrical body of said spacer being disposed within said sleeve the bottom of said cylindrical body being spaced apart from said sleeve, said spacer 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.

4. The projection television lens assembly of claim 3, wherein said spacer further comprises an upwardly raised rim extending from an upper surface of said flange, said raised rim of said spacer being securely held within a slot of said focus mount, and wherein said spacer has an opening traversing said spacer from said raised rim through said cylindrical body.

5. The projection television lens assembly of claim 4, wherein said fastener further comprises a bolt and a nut, one end of said bolt being coupled into said opening within said cylindrical body of said spacer, and an opposite end of said bolt extending radially outward through said focus mount, said nut being secured onto said bolt.

6. The projection television lens assembly of claim 5, wherein the tightening of said nut onto said bolt causes said upper surface of said flange to radially move outward toward said focus mount and to become frictionally engaged with an interior surface of said focus mount.

7. 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.

8. The focus position lock device of claim 7, further comprising

a first washer placed around said bolt, said first washer being proximate to an outer surface of said slot of said focus mount, said first washer being bigger in size than said slot of said focus mount; and

a second washer placed around said bolt, said second washer being positioned above said first washer and below said nut.

9. The focus position lock device of claim 7, wherein said lower surface of said flange of said spacer abuts said upper surface of said rim of said sleeve, and wherein said spacer is adapted for radial movement with respect to said focus mount.

10. The focus position lock device of claim 7, wherein the tightening of said nut onto said bolt draws together said spacer and said focus mount, whereby said upper surface of said flange of said spacer is brought into frictional engagement with an interior surface of said focus mount.

11. The focus position lock device of claim 7, wherein said lens cell, said focus mount, said sleeve and said spacer are each made of a plastic material.

12. The focus position lock device of claim 7, wherein said first washer is made of rubber.

13. The focus position lock device of claim 7, wherein said second washer, said bolt and said nut are each made of metal.

14. 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.

15. The projection television lens system of claim 14, wherein said lens assembly further comprises:

a first washer placed around said first bolt, said first washer being positioned on top of said first slot of said focus mount, said first washer being bigger in size than said first slot of said focus mount; and

a second washer placed around said first bolt, said second washer being positioned above said first washer and below said first nut.

16. The projection television lens system of claim 15, wherein said lens cell, said focus mount, said sleeve and said spacer are each made of a plastic material.

17. The projection television lens system of claim 15, wherein said focus mount further comprises a second slot, said second slot being positioned approximately 180°

apart from said first slot on said focus mount.

18. The projection television lens assembly of claim 15, wherein each of said grooves are aligned to define a groove axis line that is parallel to the central axis line passing through the core of said lens cell.

19. The projection television lens system of claim 18, further comprising:

a second focus position lock device for locking the focus position of said lens assembly, said second focus position lock device, further comprising;

a second sleeve projecting radially outward from and integral with said lens cell, said second sleeve being positioned approximately 180°

apart from said first sleeve on said lens cell, said second sleeve having a rim at an end distal to said lens cell, said rim of said second sleeve having two grooves on an upper surface, each of said grooves being spaced approximately 180°

apart on said rim of said second sleeve, each of said grooves being aligned to define a second groove axis line that is parallel to the central axis line passing through the core of said lens cell, said second sleeve being aligned below said second slot of said focus mount;

a second spacer comprising a cylindrical body with a radial flange at one end, said cylindrical body of said second spacer being disposed within said second sleeve, said second spacer having an upwardly raised rim extending from an upper surface of said flange, said second spacer having an opening traversing said second spacer from said raised rim through said cylindrical body, said raised rim of said second spacer being securely held within said second slot of said focus mount, a lower surface of said flange further comprising two ridges extending downward, each of said ridges being spaced approximately 180°

apart on said flange, each of said ridges of said second spacer being received within each of said grooves of said second sleeve;

a second bolt coupled to said opening of said raised rim of said second spacer, one end of said second bolt being disposed and secured within said cylindrical body of said second spacer and an opposite end of said second bolt extending outward through said second slot of said focus mount; and

a second nut secured onto said second bolt, said second nut being adapted to lock the focus position of said lens cell of said projection television lens system.

20. The projection television lens system of claim 19, wherein said lens assembly further comprises:

a third washer placed around said second bolt, said third washer being positioned on top of said second slot of said focus mount, said third washer being bigger in size than said second slot of said focus mount; and

a fourth washer placed around said second bolt, said fourth washer being positioned above said third washer and below said second nut.

21. The projection television lens assembly of claim 20, wherein the tightening of said first nut onto said first bolt and the tightening of said second nut onto said second bolt draws together said focus mount and each of said first spacer and said second spacer.

22. The projection television lens system of claim 21, wherein upon tightening each of said first nut and said second nut of said lens assembly, said upper surface of said flange of each of said first spacer and said second spacer becomes frictionally engaged with a corresponding interior surface of said focus mount.

23. The projection television lens assembly of claim 21, wherein each of said first washer and said third washer is made of a rubber material, and wherein each of said second washer and said fourth washer is made of metal.

24. 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.

25. The method of claim 24, wherein said step of locking further comprises the steps of:

coupling one end of a first bolt to an opening within a cylindrical body of said first spacer, wherein an opposite end of said first bolt extends outward through a first slot of said focus mount; and

securing a first nut onto said opposite end of said first bolt.

26. The method of claim 24, wherein said providing step further comprises:

providing said lens cell with a second sleeve that projects radially outward from and is integral with said lens cell, said second sleeve having a second spacer secured therein, said second sleeve being approximately 180°

apart from said first sleeve on said lens cell.

27. The method of claim 26, wherein said locking step further comprises:

coupling one end of a second bolt to an opening within a cylindrical body of said second spacer, wherein an opposite end of said second bolt extends outward through a second slot of said focus mount, said second slot being approximately 180°

apart from said first slot on said focus mount; and

securing a second nut onto said opposite end of said second bolt.

28. The method of claim 25, wherein said step of securing a first nut further comprises the step of first placing a first washer around said first bolt.

29. The method of claim 27, wherein said step of securing a second nut further comprises the step of first placing a second washer around said second bolt.

30. The method of claim 28, wherein said step of securing said first nut further comprises the step of tightening said first nut onto said first bolt such that an upper surface of a radial flange of said first spacer becomes frictionally engaged with a first interior surface of said focus mount.

31. The method of claim 29, wherein said step of securing said second nut further comprises the step of tightening said second nut onto said second bolt such that an upper surface of a radial flange of said second spacer becomes frictionally engaged with a second interior surface of said focus mount.

32. 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.

33. The method of claim 32, wherein the coupling step further comprises:

coupling said spacer to an integral projecting portion of said lens cell aligned along said transverse axis.