U.S. patent number 3,887,766 [Application Number 05/422,444] was granted by the patent office on 1975-06-03 for crt assembly.
This patent grant is currently assigned to Rockwell International Corporation. Invention is credited to Robert L. Caswell.
United States Patent |
3,887,766 |
Caswell |
June 3, 1975 |
CRT assembly
Abstract
A simplified means for supporting the components of a high
resolution CRT assembly without utilizing a separate rigid metal
frame is disclosed. The components including the CRT, coils and
coil positioners are supported by the magnetic shield thereby
eliminating the necessity of the intermediate rigid frame without
impairing the precision and performance of the CRT function.
Inventors: |
Caswell; Robert L. (Placentia,
CA) |
Assignee: |
Rockwell International
Corporation (El Sequndo, CA)
|
Family
ID: |
23674911 |
Appl.
No.: |
05/422,444 |
Filed: |
December 6, 1973 |
Current U.S.
Class: |
348/820;
348/E5.129; 348/825 |
Current CPC
Class: |
H01J
29/823 (20130101); H04N 5/645 (20130101) |
Current International
Class: |
H01J
29/82 (20060101); H04N 5/645 (20060101); H01j
029/06 (); H04n 005/645 () |
Field of
Search: |
;178/7.82 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Britton; Howard W.
Attorney, Agent or Firm: Hamann; H. Fredrick Weber, Jr.; G.
Donald Rubalcava; Roland G.
Claims
What is claimed is:
1. A cathode ray tube assembly for housing a CRT comprising:
at least one precision positioner means having an aperture to
accommodate said CRT;
front plate means for securing the face end portion of said
CRT;
at least one coil holder means having an aperture to accommodate
another portion of said CRT;
clamp means for securing still another portion of said CRT;
said clamp means comprising a housing having a threaded aperture
therein through which said CRT extends, a retainer ring having a
threaded outer surface, and a pliable spacer, which expands into
said aperture when said retainer ring is threaded into said
threaded aperture of the clamp housing and compresses said spacer
thereby forcing said pliable spacer to grip said CRT; and
magnetic shield means connected to said front plate means, said
precision positioner, said coil holder and said clamp housing to
provide a support structure therefor.
2. The cathode ray tube assembly as recited in claim 1 wherein said
magnetic shield further includes control circuitry attached thereto
for setting and regulating at least one of the currents of said CRT
assembly.
3. The cathode ray tube assembly as recited in claim 1 wherein said
front plate means for securing the face end of said CRT
includes:
a metal band;
a resilient member interposed between said metal band and the
interior surface of an aperture in said front mounting plate means;
and
means connected to each end of said metal band for adjusting the
portion of said metal band relative to the sides of the flared end
of said CRT and drawing said CRT against one side of said
aperture.
4. The cathode ray tube assembly as recited in claim 1 wherein said
clamp means includes washer means intermediate said retainer ring
and said pliable spacer.
5. The cathode ray tube assembly as recited in claim 1 wherein said
magnetic shield means has an enlarged, flared end adjacent said
front plate means.
6. The cathode ray tube assembly as recited in claim 1 wherein said
magnetic shield includes a pair of spaced apart layers separated by
spacers.
7. The cathode ray tube assembly as recited in claim 6 wherein each
layer of said pair of spaced apart layers has a different
configuration.
8. The cathode ray tube assembly as recited in claim 7 wherein at
least one of said layers is of substantially cylindrical
configuration.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved, low-cost, simplified means
for supporting and magnetically shielding the components used in a
high resolution CRT assembly or similar devices such as vidicons,
orthicons and image converters.
2. Description of Prior Art
Many cathode ray tube (CRT) assemblies include a high resolution
CRT and its associated components including a rigid metal structure
to which are attached the CRT, coils and micropositioners.
Reference is made to Litton Industries Model 1019 Precision
Universal Mount which is typical of a rugged mount for use with
magnetically deflected CRT's. Most known mounts of this type
utilize a rigid support structure including four steel bars with
the CRT and the related deflection, focus and other components
attached to the rigid support structure for support. A separate
magnetic shield which covers all of the CRT components including
the rigid structure is provided to prevent external magnetic
influences on CRT operation. Unfortunately, such an assembly is
quite bulky, expensive to produce and difficult to maintain.
SUMMARY OF THE INVENTION
This invention relates to an improved low cost cathode ray tube
(CRT) assembly which permits the use of the magnetic shield for (1)
shielding the CRT from external magnetic effects and (2) supporting
the CRT and all of the CRT related components. The CRT components,
including the CRT, coils, micropositioners and the like are mounted
on the magnetic shield in a unique assembly thereby eliminating
completely the use of a separate support frame and the supporting
of the components thereby. The result is elimination of extensive
assembly and maintenance problems, cost saving of material used in
the rigid structure and the like. These advantages are obtained
without reducing the performance of the CRT assembly or its
function.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a prior art CRT support
assembly.
FIG. 2 is a side view, partially in section, of one embodiment of
the assembly of the invention.
FIG. 3 is a front view of the embodiment shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following description, the same reference numeral is used in
conjunction with similar components. However, the suffix P is
included in all reference numerals associated with the prior art
device shown in FIG. 1.
FIGS. 2 and 3 are referred to concurrently. CRT assembly 10 is an
assembly which may be utilized in the system described in
co-pending applications bearing U.S. Ser. Nos. 359,590 and 359,591
both entitled Character Generating Method and System by R. L.
Caswell and G. D. Evans, respectively and assigned to the common
assignee. Magnetic shield 12 is shaped to encase all the CRT
components and substantially all of CRT 14. In a preferred
embodiment, magnetic shield 12 comprises two layers 11 and 13 of
magnetic shielding material such as permalloy or mu-metal which
provides proper magnetic shielding of a CRT. In a preferred
embodiment, the inner layer 11 of magnetic shield 12 is used as the
frame for supporting the CRT and the related components. Thus,
magnetic shield 12 has the dual purpose of magnetically shielding
CRT 14 and providing a rigid structure to which all CRT components
including the CRT are mounted. CRT 14 is secured to inner layer 11
essentially by neck clamp 16 and front clamp 18.
Referring initially to FIG. 1, there is shown one embodiment of a
typical prior art CRT assembly including a CRT and related
components. Briefly, this prior art embodiment has the CRT
components and the CRT 14P mounted on a rigid frame consisting of a
front plate 20P and an end plate 90P connected by four metal bars
or rods 80P. This rigid frame is covered by a magnetic shield 13P
which is shown broken away for convenience.
In the embodiment of the prior art shown in FIG. 1, the respective
micropositioners or holders 46P and 48P have four holes therein in
order to be mounted to the four connecting metal rods 80. This is,
of course, one requirement that is eliminated by the present
invention.
In the preferred embodiment of this invention neck clamp 16 is a
simple self-centering clamp which holds CRT 14 securely yet
minimizes substantially the possibility of a fracture. Clamp
housing 34 is mounted on inner layer 11 by suitable means such as
screws 51. Neck clamp 16 secures the neck section of CRT 14 and
includes teflon washer 28, rubber ring 30, and clamp retainer ring
32 and housing 34. Housing 34 is in the preferred embodiment,
generally annulus-shaped although other configurations are
contemplated. A substantially centrally located threaded aperture
is included in housing 34. Clamp retainer ring 32 is threaded on
its outer surface and threads into the threaded aperture in housing
34 against teflon washer 28 and rubber ring 30 until rubber ring 30
expands and securely grips the neck of CRT 14. Teflon washer 28
serves to reduce the torsion effects on rubber ring 30 which can
result from the tightening of clamp retainer ring 32.
Housing 34 also supports alignment coil 36. That is, housing 34
also includes a raised portion, or neck 34A in which coil 36 is
secured by set screws 76. For convenience, neck 34A is on the
opposite side of housing 34 relative to the threaded aperture.
Centering coil 38 is similarly supported by coil holder 40. Coil
holder 40 is mounted at inner layer 11 by suitable means such as
screws 75. Holder 40 is also generally annulus-shaped with either a
central aperture or neck for receiving centering coil 38. Coil 38
is retained in holder 40 by suitable means such as set screws 76.
In general, coils 36 and 38 are intended to be fixed relative to
CRT 14 whereby precision positioners (i.e. micropositioners) are
not required.
Conversely, focus coil 42 and deflection yoke 44 frequently require
precision adjustment. Consequently, these coils are mounted in
micropositioners 46 and 48, respectively. Typically,
micropositioners 46 and 48 are of the type described in detail in
co-pending application U.S. Ser. No. 398,731, entitled Simplified
Micropositioner by R. L. Caswell, filed on Sept. 17, 1973, which is
incorporated herein by reference. The coils 36, 38, 42, and 44 and
clamp housing 34 have apertures to accommodate the neck section of
CRT 14.
Micropositioners 46 and 48 are attached to inner layer 11 of
magnetic shield 12 by suitable means such as machine screws 50 in
each respective member spaced equally as shown in FIG. 2.
Front mounting plate 20 (better seen in FIG. 3) is attached to the
front, flared section of inner layer 11 of magnetic shield 12.
Front plate 20 has an aperture therein which is shaped to fit the
front of CRT 14. In the preferred embodiment, the front or face
fiber optics element 90 of CRT 14 projects into or through the
aperture in plate 20. Front clamp 18 is arranged within the
aperture in front plate 20. Clamp 18 includes a stainless steel
band 22 which engages or wraps around three sides of CRT 14. When
band 22 is tightened, it draws CRT 14 against one side of the
aperture in front mounting plate 20. This aperture side is lined
with rubber pad 23.
Front mounting plate 20 includes a pair of slots 24 adjacent to and
extending from the ends of the aperture. Clearance holes 77 are
provided in the face plate which holes communicate with slots 24.
Machine screws 26 which are mounted in clearance holes 77 provide
the means for tightening front clamp 18. That is, band 22 has an
enlarged section at the ends thereof. These enlarged sections
included tapped holes which engage screws 26. The enlarged section
fits in slot 24 to prevent band 20 from turning with machine screws
26 when adjusted. As screws 26 are turned, the enlarged sections of
band 22 are moved wherein band 22 is adjusted relative to CRT
14.
This type of band adjustment assures that the flared end of CRT 14
will be rigidly secured and that the prealignment adjustments will
be maintained without impairing the flexibility of rapid and simple
disassembly if required.
The control circuitry for CRT assembly 10 is channeled through
prefabricated holes in both layers of magnetic shield 12.
Electrical leads from the respective coils and the CRT anode are
brought out through insulating bushings 52 which are press fitted
in the magnetic shield 12. Focus coil 42 and deflection yoke 44
leads go to connector 54 as shown in FIG. 2. The conductor leads of
centering coil 40 and alignment coil 38 go to printed circuit board
56. PC board 56 contains circuitry which is the primary source for
regulating the currents for coils 38 and 40. Power for PC board 56
is provided through connector 54. It is advantageous to incorporate
the current control as part of the CRT assembly inasmuch as this
permits prealignment of CRT assembly 10 when it is assembled
utilizing the same current settings used when the CRT assembly is
set in operation. Prealignment of the CRT assembly using these
settings provides more accuracy and eliminates the effort of
additional later current settings.
The time and materials saved by elimination of the frame and
attachments thereto of the prior art as well as incorporation of
the centering and alignment current settings into the same physical
assembly can readily be seen.
The mechanical characteristics, i.e. the cross-section moment of
inertia and Young's modulus of a typical magnetic shield are well
adapted for use as a rigid support when properly rigid attachments
to it are made as in the present invention. Frequently the magnetic
shield weighs more than the total of other CRT components; hence
the magnetic properties of the shield (which could be impaired by
high stresses) are not significantly affected by supporting the
weight of the other CRT components.
Access to the CRT base 58 to connect or remove the CRT socket which
plugs into CRT base 58 is made by removing shield cap 60.
In describing the actual assemblng of CRT assembly 10 consider that
inner magnetic shield 11 is the mounting structure for all of the
CRT components; i.e. all the CRT components, including front plate
20, will be attached to the inner magnetic shield. The deflection
yoke 44 is mounted in the micropositioner 48 which is installed in
the inner magnetic shield through the unflared end of the shield.
The same procedure is followed with focus coil 42 and
micropositioner 46. The respective electrical leads are fed through
the insulating bushings in prefabricated holes in inner magnetic
shield 11. Next, centering coil 38 is mounted on coil holder 40 and
positioned in inner magnetic shield 11 through the rear section of
the inner magnetic shield 11. The coil leads are fed through
prefabricated holes in inner magnetic shield 11. Finally, alignment
coil 36 is mounted on neck clamp housing 34 and positioned in the
inner magnetic shield assembly and its respective leads are fed
through the insulated, prefabricated holes in magnetic shield 11.
Each respective micropositioner and holder is physically attached
to the magnetic shield by machine screws 50 or 51. Spacers 53 are
positioned on the surface of inner magnetic shield 11 to support
outer magnetic shield 13. These spacers may be in the nature of a
plurality of individual stand offs or alternatively appropriate
plate-like members. In the preferred embodiment, spacers 53 are
generally rectangular with substantially circular apertures
therein. Thus, outer layer 13 is rectangular while inner layer 11
is circular. Of course, these configurations can be readily
modified without departing from the inventive teachings herein.
The respective electrical leads are fed through holes in outer
magnetic shield 13, insulating bushings 52 are fitted over the
leads, and the bushings are press-fitted through the prefabricated
holes in outer magnetic shield 13. PC board 56 is mounted on outer
magnetic shield 13 and centering coil 38 leads and alignment coil
36 leads are connected to PC board 56. PC board 56 is electrically
connected to connector 54. The CRT anode 57 lead, deflection and
focus coil leads also are fed through prefabricated holes and
through bushings and are connected directly to connector 54. Front
mounting plate 20 is attached to the front of the inner shield
11.
The CRT 14 is now ready to be mounted. The CRT neck is passed
through the front end of the magnetic shield assembly and through
the apertures in deflection yoke 46, focus coil 44, centering coil
40, alignment coil 38, clamp housing 30, and neck clamp 16. As this
is being done the anode lead is attached to the CRT. Neck clamp 16
is lightly adjusted on the CRT neck. At this point front clamp 18
is installed in front mounting plate 20 and adjusted to secure the
flared end of CRT 14. Neck clamp 16 is then adjusted to secure the
neck of CRT 14. The shield cap is attached and CRT 10 is now
assembled and ready to be aligned.
Once the CRT assembly is aligned and ready for operation, it is
physically mounted to a system by its front mounting plate, i.e.
supported by only the front mounting plate, and installed for
operation vertically with the front mounting plate face up. The
mechanical rigidity of this CRT assembly is more than adequate to
withstand operation use without noticeable degradation of the
alignment.
Thus, there has been shown a CRT assembly without the conventional
rigid structure, and which maintains the precision and performance
of the CRT function by utilizing the magnetic shield as the
supporting structure as well as for magentic shielding
purposes.
In addition to eliminating the rigid metal structure, another
advantage of mounting the CRT components directly to the shield is
that it can be accomplished by simply tapping four holes in each
respective assembly to be mounted and engaging same by four machine
screws through four holes in the shield. Whereas in the
conventional rugged type mount assembly four precision jig bored
holes are required in each component to be mounted on the frame to
accommodate the four rods of the structure and in addition four
tapped holes and four set screws are necessary to secure each mount
to the rods and finally the mounting of the magnetic shield onto
the rigid structure requires additional tapped holes and set screws
to secure the magnetic shield to the rigid structure.
Thus, elimination of the frame in a CRT assembly not only
eliminates the cost of the frame and additional cost for attachment
of other CRT components to it but the size of the shield is also
reduced and thus it is less expensive to manufacture.
The embodiment shown and described is illustrative only. It is not
meant to be limitative of the invention. Certain modifications will
be suggested to those skilled in the art. For example, outer layer
13 may be eliminated in some cases. Moreover, it should be clear
that the assembly is fabricated of suitable non-magnetic material
such as plastic, aluminum and the like, except for shield 12 which
is a high permeability at low induction magnetic shielding
material. The scope of the invention is to be defined only by the
claims appended hereto.
* * * * *