Information
-
Patent Grant
-
6188171
-
Patent Number
6,188,171
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Date Filed
Tuesday, June 15, 199925 years ago
-
Date Issued
Tuesday, February 13, 200123 years ago
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Inventors
-
-
Examiners
Agents
- Tripoli; Joseph S.
- Irlbeck; Dennis H.
-
CPC
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US Classifications
Field of Search
US
- 513 407
- 513 402
- 513 479
- 513 482
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International Classifications
-
Abstract
A cathode-ray tube has an internal magnetic shield and at least one contact spring attached to the shield. The shield includes a land with an outer edge and an inner edge. The spring includes two portions, an improved clasp portion attached to the shield at the land, and a contact leaf portion. The improved clasp portion includes a flat body with a reverse bend hook at a first end, and a latch and a catch at an end opposite to the first end. The hook engages the outer edge of the land, and the latch engages the inner edge of the land. The catch includes a bent end portion that forms an acute angle with the remainder of the catch. The bent end portion is positioned to engage the inner edge of the land if the spring is rotated about the hook. The leaf portion is connected to and extends from the latch.
Description
This invention relates to a cathode-ray tube having an internal magnetic shield with at least one contact spring attached thereto.
BACKGROUND OF THE INVENTION
A color cathode-ray tube (CRT) typically has an internal magnetic shield located within a funnel thereof to reduce the influence of magnetic fields on electron beam trajectories. The shield is usually made of cold-rolled steel and fastened to a shadow mask frame. A flexible contact spring sometimes is attached to the shield or frame to make electrical contact with a conductive coating on the inner surface of the tube funnel. An early method of attaching a contact spring was by welding.
However, the welding method often resulted in undesirable loose particles in the tube.
There have been several improvements suggested to overcome the problem associated with welding contact springs to either a frame or an internal magnetic shield. For example, U.S. Pat. No. 4,310,779, issued to Penird et al., on Jan. 12, 1982, and U.S. Pat. No. 4,433,267, issued to Kuryla et al., on Feb. 21, 1984, disclose contact springs that include a wrap-around clip that snaps onto a flute formed at the rear end of a magnetic shield. U.S. Pat. No. 5,126,624, issued to Ji, on Jun. 30, 1992, discloses a contact spring that includes a triangular type head that fits within a hole in a shadow mask frame. U.S. Pat. No. 4,670,686, issued to Muenkel et al., on Jun. 2, 1987, discloses a spring with a leaf tab and stiffening structure that is inserted through two opposed slots in an internal magnetic shield. Each of the foregoing contact springs includes one or more disadvantages. The simpler ones may work loose or move around too much, and the more complex ones are costly to manufacture. Therefore, there is a need for a contact spring with a simple design, which will be easy to insert and will not move around.
An improved contact spring is disclosed in U.S. patent application Ser. No. 09/149,320, filed on Sep. 8, 1998, by A. W. Bucher now allowed. The Bucher application claims a contact spring that includes a clasp with a hook and latch that can be snapped onto a land of and internal shield. It has been found that there are conditions that may even cause the contact spring of Bucher to disengage from an internal shield. The present invention provides an improvement in the type of contact spring shown in the Bucher application that prevents such disengagement.
SUMMARY OF THE INVENTION
A cathode-ray tube has an internal magnetic shield and at least one contact spring attached to the shield. The shield includes a land with an outer edge and an inner edge. The spring includes two portions, an improved clasp portion attached to the shield at the land, and a contact leaf portion. The improved clasp portion includes a flat body with a reverse bend hook at a first end, and a latch and a catch at an end opposite to the first end. The hook engages the outer edge of the land, and the latch engages the inner edge of the land. The catch includes a bent end portion that forms an acute angle with the remainder of the catch. The bent end portion is positioned to engage the inner edge of the land if the spring is rotated about the hook. The leaf portion is connected to and extends from the latch.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1
is a cross-sectional view of the front portion of a cathode-ray tube illustrating a pair of contact springs attached to an internal magnetic shield within the tube.
FIG. 2
is a cross-sectional view taken along line
2
—
2
of FIG.
1
.
FIG. 3
is a plan view of a portion of the internal magnetic shield of
FIG. 1
, at a spring location.
FIG. 4
is a cross-sectional view taken along line
4
—
4
of FIG.
3
.
FIG. 5
is a bottom view of a contact spring of FIG.
1
.
FIG. 6
is a cross-sectional view taken along line
6
—
6
of FIG.
5
.
FIG. 7
is a plan view of a portion of the internal magnetic shield with a contact spring attached thereto.
FIG. 8
is a cross-sectional view taken along line
8
—
8
of FIG.
7
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2
show a cathode-ray tube
10
having a faceplate panel
12
sealed to a funnel
14
thereof along an edge
16
of the panel
12
. The tube
10
has an internal magnetic shield
18
disposed therein proximate an inner surface of the funnel
14
. The magnetic shield
18
is fastened to a shadow mask frame
22
, which is supported by mounting studs
24
that extend inwardly from the faceplate panel
12
. The inner surface
20
of the funnel
14
has a conductive coating
26
thereon extending along the surface
20
to a predetermined distance from the edge
16
. This conductive coating
26
comprises a graphite coating which serves as the positive anode for the tube. A pair of contact springs
28
are attached at the rear portion
30
of the internal magnetic shield
18
for effecting an electrical connection between the shield
18
and the conductive coating
26
.
FIGS. 3 and 4
show a part of the rear portion
30
of the internal magnetic shield
18
that is at a spring location. The part of the rear portion
30
has a land
31
that is raised from the continuation of the shield contour by a step riser
32
. At the spring location, the step riser
32
includes an elongated aperture
34
therein. A small portion of the step riser
32
forms an angled lip
37
on the land
31
. The distal end of the lip
37
forms an inner edge
35
of the land
31
, opposite an outer edge
36
of the land
31
. The outer edge
36
of the land
31
includes a notch
38
at the spring location, and the land
31
also includes a reinforcing bead
40
that parallels the inner and outer edges of the land
31
.
FIGS. 5 and 6
show the contact spring
28
having two portions, a clasp
42
and a contact leaf
44
. The clasp
42
provides for attachment of the contact spring
28
to the internal magnetic shield
18
, and the contact leaf
44
is cantilevered from the clasp portion
42
to provide contact to the internal conductive coating
26
on the inner surface of the tube. The clasp
42
includes a flat body
41
separating a reverse bend hook
46
, forming an acute angle with the body
41
, and a latch
48
and catch
43
at the proximal end of the clasp
42
. The leaf
44
extends from the latch
48
and includes two separated parallel arms,
50
and
52
, each arm having round contact surfaces
54
and
56
, respectively, at the distal ends thereof.
FIGS. 7 and 8
show the contact spring
28
connected to the internal magnetic shield
18
. The hook
46
engages the outer edge of the land
31
of the shield
18
at the notch
38
, and the latch
48
engages the inner edge
35
of the land
31
of the shield
18
at the aperture
34
. The catch
43
is a safety device to prevent disengagement of the spring
28
from the land
31
, when an excessive force is applied to the contact leaf
44
causing the spring
28
to rotate about the hook
46
. Such a force can be applied accidentally during handling of the magnetic shield
18
. The catch
43
accomplishes this safety function by hooking onto or catching the angled lip
37
of the land
31
, when the contact leaf
44
of the spring
28
rotates away from the magnetic shield. During installation of the spring
28
, the hook
46
is positioned first against the land
31
and serves as a pivot for rotating the spring, so that the latch
48
enters the aperture
34
and engages the inner edge
35
of the land
31
of the shield
18
. At this point, the catch
43
passes around the land
31
, where it is positioned to catch the land, if the spring
28
is rotated.
The interaction of the contact spring clasp portion
42
with the rear portion
30
of the shield provides a self-tightening feature when the contact leaf portion
44
contacts the conductive coating
26
on the inner wall of the funnel
14
. As the contact leaf portions
44
of both springs contact the inside of the funnel, they deflect toward the shield
18
and cause the latches
48
to further close around the inner and outer edges,
35
and
36
, respectively, of the shield lands.
The contact spring of the present invention is simpler in design and easier to install than most previous contact springs. Furthermore, the present contact spring eliminates the scraping between parts that occurs during the installation of many prior contact springs.
Claims
- 1. In a cathode-ray tube having an internal magnetic shield and at least one contact spring attached to said shield, said shield including a land with an outer edge and an inner edge, said spring including two portions, a clasp portion attached to the shield at said land, and a contact leaf portion, the improvement comprisingsaid clasp portion including a flat body with a reverse bend hook at a first end, and a latch and a catch at an end opposite to the first end, said hook engaging the outer edge of said land, said latch engaging the inner edge of said land, said catch including a bent end portion that forms an acute angle with the remainder of said catch, said bent end portion is positioned to engage said inner edge of said land when said spring is rotated about said hook, and said leaf portion is connected to and extends from said latch.
- 2. The tube as defined in claim 1, wherein said latch includes two outer portions and said catch is spaced and separated from said latch and is positioned between the two outer portions of said latch.
- 3. The tube as defined in claim 1, wherein said contact leaf portion is connected to and extends from said latch, and a distal end of said leaf portion contacts an interior surface of said tube.
US Referenced Citations (6)