Television – Video display – Projection device
Reexamination Certificate
1999-05-06
2001-09-04
Eisenzopf, Reinhard J. (Department: 2614)
Television
Video display
Projection device
C359S819000, C359S822000, C359S823000
Reexamination Certificate
active
06285416
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to projection television lens assemblies and in particular, to a focus position lock device employed in such assemblies.
BACKGROUND OF THE INVENTION
Projection televisions are well known. In general, a projection television set or projector includes three cathode ray tubes (CRTs), corresponding to the primary colors, red, blue, and green. Associated with each of the CRTs is a projection lens assembly, which is comprised of a plurality of optical lens units. Overall, a CRT has an attached faceplate, and the function of the lens assembly is to magnify the image appearing on the faceplate of the CRT, and thereby project it onto a viewing screen, which is much larger than the faceplate of the CRT. For a typical layout of the optical lens units in a projection television lens assembly see U.S. Pat. No. 4,776,681.
Basically a projection television lens assembly is made up of a plastic tubular member, generally referred to as a lens cell. It is the lens cell that has a plurality of optical lens units mounted within it. The lens cell itself is mounted within another plastic tubular member referred to as a focus mount. The mounting of the lens cell within the focus mount allows axial movement of one with respect to the other, which results in focusing the image onto the screen. An apparatus for achieving such adjustment is shown in U.S. Pat. No. 5,276,555. After the image is focused, the axial position of the lens cell is then locked with respect to the focus mount. In the past, the basic approach has been to screw in a bolt through a slot on the focus mount, and into a boss that is integral with the lens cell, which was then followed by a washer and a nut over the bolt. By turning the nut clockwise, that is, tightening the nut, the lens cell and the focus mount were pulled together to create a frictional lock. However, when the nut was tightened securely to maintain the focus of the projection television lens assembly, this led to the deformation of the plastic lens cell and the focus mount. The tightening of the nut also caused the lens cell containing the optical lens units within the focus mount to tilt, thus, causing an increase in flare on the image appearing on the screen.
An object of the invention is to provide a focus position lock device that maintains a focus position in a projection television lens system, and prevents any tilting of the lens cell containing the optical lens units. Another object of the invention is to provide a focus position lock device that prevents any distortion of the lens cell and the focus mount in a projection television lens assembly.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a projection television lens assembly that substantially obviates one or more of the limitations and disadvantages of the related art. The present invention provides a solution to the problems described above relating to lens cell assemblies in a projection television. Specifically the invention provides a means for mounting a lens cell in a focus mount so that when it is locked in place after focusing, the locking step does not result in tilting the lens cell.
In accordance with the broadest aspect of the present invention, a spacer, made of a non-rigid material, is interposed between the lens cell and the focus mount of a projection television lens assembly, where the spacer is adapted for radial movement. A fastener coupled to the spacer, is adapted for positioning the spacer and for locking a focus position of the projection television lens assembly. In a preferred embodiment, the spacer is received into a sleeve that projects radially outward from and is integral with the lens cell. The sleeve has a rim at an end distal to the lens cell, and the rim has two grooves on an upper surface, with each of the grooves being spaced approximately 180° apart and with each of the grooves being aligned to define a groove axis that passes through the grooves, the groove axis line being parallel to the central axis line passing through the center of the lens cell. Further, the spacer has a cylindrical body with a radial flange at one end. The cylindrical body of the spacer is disposed within the sleeve and where the bottom of the cylindrical body of the spacer does not physically contact the sleeve, thus, defining a gap between the bottom of the spacer and the sleeve. Moreover, the spacer has two ridges that extend downward from a lower surface of the radial flange, each of the ridges being received into the two respective grooves on the sleeve. The receipt of the ridges into the grooves prevents the spacer from rotating within the sleeve. The spacer further 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 fastener is coupled to an opening in the spacer. The fastener is adapted for positioning the spacer and for locking the focus position. In one embodiment, the fastener comprises a bolt and a nut, where 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. The nut is secured onto the bolt. After establishing a focus position for the lens cell assembly, the nut is tightened onto the bolt in order to lock the focus position of the lens cell assembly. The tightening of the nut causes the spacer to rise radially within the sleeve and causes an upper surface of the radial flange of the spacer to frictionally engage an interior surface of the focus mount. Since the spacer is restricted from moving laterally and from rotating within the sleeve, during tightening of the nut onto the bolt, tilting of the lens cell is prevented and the focus position of the lens assembly is maintained. In another embodiment, a second sleeve identical in construction to the first sleeve is positioned approximately 180° apart from the first sleeve. Furthermore, a second spacer, made of a non-rigid material, is interposed between the lens cell and the focus mount, the second spacer being identical in construction to the first spacer. A second fastener is coupled to the second spacer, where the second fastener is adapted for positioning the second spacer and for locking the focus position of the projection television lens assembly.
In yet another embodiment of the invention, a method is provided for locking a focus position in a projection television lens assembly that comprises a lens cell and a focus mount, where the lens cell includes a plurality of lens units mounted therein, and where the lens cell is telescopically mounted within the focus mount. The method comprises the steps of interposing a spacer between the lens cell and the focus mount, the spacer being adapted for radial movement. The method further includes establishing a focus position for said projection television lens assembly and locking the focus position of the projection television lens assembly, while preventing the tilting of the lens cell within the focus mount. The interposing step further includes providing the lens cell with a sleeve that projects radially outward from and is integral with the lens cell, and where the sleeve has a spacer secured therein. The step of locking further comprises the step of coupling one end of a bolt to an opening within the spacer, where an opposite end of the bolt extends outward through a slot in the focus mount. The method further includes the step of securing a nut onto the bolt and tightening the nut such that an upper surface of a radial flange of the spacer becomes frictionally engaged with an interior surface of the focus mount. Alternatively, the method includes the step of providing the lens cell with a second sleeve that projects radially outward and is integral with the lens cell, where the respective sleeves are spaced approximately 180° apart from each other on the lens cell. Further, the method includes coupling one end of a second bolt to an opening within the second
Mitchell John David
Okorocha Livyn Obiajuru
Corning Precision Lens
Eisenzopf Reinhard J.
Michaelsen Alfred L
Tran Trang U.
LandOfFree
Apparatus and method for a focus position lock device for a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for a focus position lock device for a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for a focus position lock device for a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2452770