CA1043846A - Cathode ray tube - Google Patents
Cathode ray tubeInfo
- Publication number
- CA1043846A CA1043846A CA249,392A CA249392A CA1043846A CA 1043846 A CA1043846 A CA 1043846A CA 249392 A CA249392 A CA 249392A CA 1043846 A CA1043846 A CA 1043846A
- Authority
- CA
- Canada
- Prior art keywords
- conductive layer
- cathode ray
- ray tube
- glass
- envelope
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/86—Vessels; Containers; Vacuum locks
- H01J29/88—Vessels; Containers; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/88—Coatings
- H01J2229/882—Coatings having particular electrical resistive or conductive properties
Landscapes
- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
- Electrodes For Cathode-Ray Tubes (AREA)
Abstract
ABSTRACT:
By roughening the glass surface of the envelope of a cathode ray tube below the conductive layer, a good adhesion of the conductive layer to the glass surface is obtained. A good contact is obtained by smoothing the glass surface below the layer at the area of the point of contact of a contact spring with the conductive layer, which contact spring constitutes the connection between an electrode and the conductive layer, and flash-overs (sparks) will not occur.
- ? -
By roughening the glass surface of the envelope of a cathode ray tube below the conductive layer, a good adhesion of the conductive layer to the glass surface is obtained. A good contact is obtained by smoothing the glass surface below the layer at the area of the point of contact of a contact spring with the conductive layer, which contact spring constitutes the connection between an electrode and the conductive layer, and flash-overs (sparks) will not occur.
- ? -
Description
PHN. 8225.
4~
"Cathode ray tube" -' ' :' ' :.
The invention relates to a cathode ray tube ;
for displaying pictures and cc~prising in an evacuated glass enveloFe means to generate at least one electmn beam, a display screen on a wall part of the envelope which constitutes the display windbw, an electrically ;~
conductive layer on a wall p æt of the envelope which is present between the said neans and the display screen, and an electmde which is connected to said ;
layer by nEans of a oontact spring which presses ~;against the conductive layer.
Su~h a cathode ray tbbe is kncwn from the United States Patent Specification 2,829,292, in which resilient oontacts constitute the ccnnection between one of the electm des of the nEans to generate an electrDn beam and an electri~lly oonductive layer.
This layer in turn constitutes the oonnection to the display screen which serves as a target for the said electnon beam~s) and hence obtains the character of ~
a seoond anode. It is the object of the oonductive ~;
layer bo create a field-free spaae also in a region '~':'!.. '.'".''".' ' of the cathode ray tube where the electran beam(s) ~ -is n3t deflected. In similar cathode ray tubes of the shad~w nask type which are used for the display of oolour pictures, the so~called shad~w mask .; :
' ' .,'':
PHN. 8225.
~0;~3~
:
which is usually connected to the oonductive layer via resilient oDntacts is present in front of the display `~
screen.
It has been found that at the area where the resilient oontacts press ag~inct the conductive layer (the contact place) electric flash-overs (sparks) occur. As a result of said flashrovars, the oonductive layer is sputtered away around the contact place after a nu~ber of hours in cperation, so that the distance ;~
over which the fl~shrcwels take pla oe becomes larger. -It has been found that said phenomenon can even become visible on the display screen. Xbreover, such flash-overs may damage electranic circuits in the devioe in which the cathDde ray tube is present.
It is the cbject of the invention to prevent such fllsh-cwers and to ensure a good contact and to neintain the good adhesion of the conductive layer to -the envelope.
Ac~r~ding to the invention, a cathode ray tube ~t -of the kind mentioned in the first paragraph is charac-terized in that the glass surace of the envelope below said oonductive layer is rcugh with the exception of the place where the oontact spring presses against the conductive layer, in which place the glass surface is smDothd over a small surfaoe part. This can be realized by pDlishing the glass surfa oe of the envelope belcw the cQnductive layer or by ~mo~hing the .' ': '.
- 3 - ~
... :
. .
- ' PHN 8225 ' 9.12.75 4~;
.--die with which the envelope is manufactured in and around the place where the corltact point will be pro-vided.
The invention is based on the recognition that the sparks occur when the contact spring presses on a projection of the glass protruding through the conduc-tive layer. In this case the contact is maintained only by flash-overs. The roughness of the glass which is the cause of the projections, however, promotes a good, adhesion of the conductive layer to the envelope.
With the construction according to this invention a , good adhesion of the layer is ensured and a good con-tact is obtained in which no flash-overs occur.
~elow the contact spring the surface roughness ',15 of the glass should be at least 25% smaller than the layer thickness of the conductive layer.
The conductive layer preferably has a thick-ness between 8 and 12/um. The glass surface preferably has a surface roughness'of approximately 20/um (ap-proximatel~ 800 ru) and at the area of the contact ' less th&n 3/um (approximately 120 ru). Suxface rough-ness is to be understood to mean herein the average , of the absolute values of the deviation from a 100%
smooth surface'which indicates the average level of -' the surface with which a sensing pin having a radius , of curvature R of 3/um is measured.
The invention will now be described in greater .,.' ~ 4 ,- '~ , 9.12.75 ~043~46 detail with reference to a drawing in whic-h:
Figure 1 shows a cathode ray tube according to the invention, Figure 2 shows a bad contact, whil:e Figure 3 shows a graph indicating the glass roughness measurement, and ~ Figure 4 shows the influence of the use of the¦ . invention, while 1 Figure 5 shows a cathode ray tube for dis-¦ 10 playing coloured pictures.
J Figure 1 shows a cathode ray tube according to the invention. A display screen 3 is present in the evacuated envelope 1 on the wall part which con-stitutes the display window 2. The envelope 1 moreover comprises means 4 to generate an electron beam. In most j cathode ray tubes the last electrode 5 of the said means 4 are brought at a high potential to accelerate the electron beam. Said high potential is applied via contact springs 6 extending from the electrode 5 and contacting the conductive layer 7 which is present on a wall part between the display screen 3 and the said means 4.
The part of the en~elope wh~ch is covered with the conductive layer is rather rough (see also Figure 3). This has for its result that, as is shown - in Figure 2 J projections of the glass 8 protrude through the conductive layer 7. This is the case in .
' . : ' . , ' ~ - 5 9.~2-75 :~a43~4~
particular when the conductive layer is provided by spraying. When the metal contact spring 6 presses against such a projection 8, sparks will cause the transport of charge carriers from the conductive layer 7 to the contact spring 6. As a result of this the conductive layer 7 is sputtered away near the contact point and the track to be covered by the sparks ~ecomes larger.
Figure 3 shows a glass roughness measurement.
This measurement has been performed with a sensing instrument, A very sharp sensing pin suspended from an extremely truly processed parallel guide is dragged over the surface to be checked. The measuring pressure is extremely low so that no scratches are formed. The sensing pin which has a given radius of curvature follows nearly all unevenesses of the surface. ~The ~ relative horizontal movement d and vertical movement h of the sensing pin are ~hown on an enlarged scale in Figure 3. In the case of Figure 3 the radius of curvature of the sensing pin is 3 um. Therefore Fi-,J ,,. ~ /
gure 3 is a very good representation of t~e rough glass surface.
Taking into account the fact that the conduc-tive layer usually has a thickness from 8 to 12/um, it will be obvious that projections of the glass protrude through the conductive layer.
It will ~e obvious from Figure 4 that at the ' ~ - .
, 9.12.75 4~ ;
area of the contact of contact spring 6 with the con-ductive layer7a readily conductive contact which does not give rise to the formation of sparks has been ob-tained by smoothing the glass surface of the~nvelope 1.
It will be obvious that the invention is Dot restricted to cathode ray tubes shown in Figure 1 and that it also relates to cathode ray tubes for displaying coloured pictures as is shown in Figure 5.
This kind of tubes is usually provided with a colour selection electrode 9 (also termed shadow mask) which is secured to a support~ng frame 12 and consists of a plate-shaped electrode having round or elongate aper-tures which is present in front of the display screen ; 15 and is conductively connected to the conductive layer by mean~ of contact spring~ 10. Such a cathode ray . ~ . . .
tube usually comprises in addition a screening cap 11. The invention can successfully be used in those .
cases in which a good high voltage contact by means of contact springs with the conductive layer is neces-sary, ., .
-. , .
, .~ ~' ~ .. ' . . .
.
4~
"Cathode ray tube" -' ' :' ' :.
The invention relates to a cathode ray tube ;
for displaying pictures and cc~prising in an evacuated glass enveloFe means to generate at least one electmn beam, a display screen on a wall part of the envelope which constitutes the display windbw, an electrically ;~
conductive layer on a wall p æt of the envelope which is present between the said neans and the display screen, and an electmde which is connected to said ;
layer by nEans of a oontact spring which presses ~;against the conductive layer.
Su~h a cathode ray tbbe is kncwn from the United States Patent Specification 2,829,292, in which resilient oontacts constitute the ccnnection between one of the electm des of the nEans to generate an electrDn beam and an electri~lly oonductive layer.
This layer in turn constitutes the oonnection to the display screen which serves as a target for the said electnon beam~s) and hence obtains the character of ~
a seoond anode. It is the object of the oonductive ~;
layer bo create a field-free spaae also in a region '~':'!.. '.'".''".' ' of the cathode ray tube where the electran beam(s) ~ -is n3t deflected. In similar cathode ray tubes of the shad~w nask type which are used for the display of oolour pictures, the so~called shad~w mask .; :
' ' .,'':
PHN. 8225.
~0;~3~
:
which is usually connected to the oonductive layer via resilient oDntacts is present in front of the display `~
screen.
It has been found that at the area where the resilient oontacts press ag~inct the conductive layer (the contact place) electric flash-overs (sparks) occur. As a result of said flashrovars, the oonductive layer is sputtered away around the contact place after a nu~ber of hours in cperation, so that the distance ;~
over which the fl~shrcwels take pla oe becomes larger. -It has been found that said phenomenon can even become visible on the display screen. Xbreover, such flash-overs may damage electranic circuits in the devioe in which the cathDde ray tube is present.
It is the cbject of the invention to prevent such fllsh-cwers and to ensure a good contact and to neintain the good adhesion of the conductive layer to -the envelope.
Ac~r~ding to the invention, a cathode ray tube ~t -of the kind mentioned in the first paragraph is charac-terized in that the glass surace of the envelope below said oonductive layer is rcugh with the exception of the place where the oontact spring presses against the conductive layer, in which place the glass surface is smDothd over a small surfaoe part. This can be realized by pDlishing the glass surfa oe of the envelope belcw the cQnductive layer or by ~mo~hing the .' ': '.
- 3 - ~
... :
. .
- ' PHN 8225 ' 9.12.75 4~;
.--die with which the envelope is manufactured in and around the place where the corltact point will be pro-vided.
The invention is based on the recognition that the sparks occur when the contact spring presses on a projection of the glass protruding through the conduc-tive layer. In this case the contact is maintained only by flash-overs. The roughness of the glass which is the cause of the projections, however, promotes a good, adhesion of the conductive layer to the envelope.
With the construction according to this invention a , good adhesion of the layer is ensured and a good con-tact is obtained in which no flash-overs occur.
~elow the contact spring the surface roughness ',15 of the glass should be at least 25% smaller than the layer thickness of the conductive layer.
The conductive layer preferably has a thick-ness between 8 and 12/um. The glass surface preferably has a surface roughness'of approximately 20/um (ap-proximatel~ 800 ru) and at the area of the contact ' less th&n 3/um (approximately 120 ru). Suxface rough-ness is to be understood to mean herein the average , of the absolute values of the deviation from a 100%
smooth surface'which indicates the average level of -' the surface with which a sensing pin having a radius , of curvature R of 3/um is measured.
The invention will now be described in greater .,.' ~ 4 ,- '~ , 9.12.75 ~043~46 detail with reference to a drawing in whic-h:
Figure 1 shows a cathode ray tube according to the invention, Figure 2 shows a bad contact, whil:e Figure 3 shows a graph indicating the glass roughness measurement, and ~ Figure 4 shows the influence of the use of the¦ . invention, while 1 Figure 5 shows a cathode ray tube for dis-¦ 10 playing coloured pictures.
J Figure 1 shows a cathode ray tube according to the invention. A display screen 3 is present in the evacuated envelope 1 on the wall part which con-stitutes the display window 2. The envelope 1 moreover comprises means 4 to generate an electron beam. In most j cathode ray tubes the last electrode 5 of the said means 4 are brought at a high potential to accelerate the electron beam. Said high potential is applied via contact springs 6 extending from the electrode 5 and contacting the conductive layer 7 which is present on a wall part between the display screen 3 and the said means 4.
The part of the en~elope wh~ch is covered with the conductive layer is rather rough (see also Figure 3). This has for its result that, as is shown - in Figure 2 J projections of the glass 8 protrude through the conductive layer 7. This is the case in .
' . : ' . , ' ~ - 5 9.~2-75 :~a43~4~
particular when the conductive layer is provided by spraying. When the metal contact spring 6 presses against such a projection 8, sparks will cause the transport of charge carriers from the conductive layer 7 to the contact spring 6. As a result of this the conductive layer 7 is sputtered away near the contact point and the track to be covered by the sparks ~ecomes larger.
Figure 3 shows a glass roughness measurement.
This measurement has been performed with a sensing instrument, A very sharp sensing pin suspended from an extremely truly processed parallel guide is dragged over the surface to be checked. The measuring pressure is extremely low so that no scratches are formed. The sensing pin which has a given radius of curvature follows nearly all unevenesses of the surface. ~The ~ relative horizontal movement d and vertical movement h of the sensing pin are ~hown on an enlarged scale in Figure 3. In the case of Figure 3 the radius of curvature of the sensing pin is 3 um. Therefore Fi-,J ,,. ~ /
gure 3 is a very good representation of t~e rough glass surface.
Taking into account the fact that the conduc-tive layer usually has a thickness from 8 to 12/um, it will be obvious that projections of the glass protrude through the conductive layer.
It will ~e obvious from Figure 4 that at the ' ~ - .
, 9.12.75 4~ ;
area of the contact of contact spring 6 with the con-ductive layer7a readily conductive contact which does not give rise to the formation of sparks has been ob-tained by smoothing the glass surface of the~nvelope 1.
It will be obvious that the invention is Dot restricted to cathode ray tubes shown in Figure 1 and that it also relates to cathode ray tubes for displaying coloured pictures as is shown in Figure 5.
This kind of tubes is usually provided with a colour selection electrode 9 (also termed shadow mask) which is secured to a support~ng frame 12 and consists of a plate-shaped electrode having round or elongate aper-tures which is present in front of the display screen ; 15 and is conductively connected to the conductive layer by mean~ of contact spring~ 10. Such a cathode ray . ~ . . .
tube usually comprises in addition a screening cap 11. The invention can successfully be used in those .
cases in which a good high voltage contact by means of contact springs with the conductive layer is neces-sary, ., .
-. , .
, .~ ~' ~ .. ' . . .
.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. A cathode ray tube for displaying pictures and comprising in an evacuated glass envelope means to generate at least one electron beam, a display screen on a wall part of the envelope which constitutes the display window, an electrically conductive layer on a wall part of the envelope which is present be-tween the said means and the display screen, and an electrode which is connected to said layer by means of a contact spring which presses against the conduc-tive layer, characterized in that the glass surface of the envelope below said conductive layer is rough with the exception of the place where the contact spring presses against the conductive layer, in which place the glass surface is smoothed over a small surface part.
2. A cathode ray tube as claimed in Claim 1, characterized in that the surface roughness of the glass below the contact spring is at least 25% smaller than the thickness of the conductive layer.
3. A cathode ray tube as claimed in Claim 1, characterized in that the surface roughness of the glass below the contact spring is less than 3µm and the thickness of the conductive layer is approxima-tely between 8 and 12µm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19752555765 DE2555765C2 (en) | 1975-12-11 | 1975-12-11 | Picture display tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043846A true CA1043846A (en) | 1978-12-05 |
Family
ID=5964096
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA249,392A Expired CA1043846A (en) | 1975-12-11 | 1976-04-01 | Cathode ray tube |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS583582B2 (en) |
| CA (1) | CA1043846A (en) |
| DE (1) | DE2555765C2 (en) |
| GB (1) | GB1502510A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54141556A (en) * | 1978-04-26 | 1979-11-02 | Matsushita Electronics Corp | Manufacture for cathode-ray tube |
-
1975
- 1975-12-11 DE DE19752555765 patent/DE2555765C2/en not_active Expired
- 1975-12-29 GB GB5297575A patent/GB1502510A/en not_active Expired
-
1976
- 1976-01-21 JP JP51005094A patent/JPS583582B2/en not_active Expired
- 1976-04-01 CA CA249,392A patent/CA1043846A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS583582B2 (en) | 1983-01-21 |
| DE2555765B1 (en) | 1977-06-02 |
| DE2555765C2 (en) | 1978-01-12 |
| GB1502510A (en) | 1978-03-01 |
| JPS5272157A (en) | 1977-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0209346A2 (en) | Colour cathode ray tube | |
| CA1043846A (en) | Cathode ray tube | |
| US20020140341A1 (en) | Ac-driven surface discharge plasma display panel having transparent electrodes with minute openings | |
| US4119885A (en) | Cathode ray tube | |
| US20020105262A1 (en) | Slim cathode ray tube and method of fabricating the same | |
| EP0392615B1 (en) | Colour display tube and display device comprising such a colour display tube | |
| US4626737A (en) | Mask focusing color picture tube | |
| US4567400A (en) | CRT Comprising metallized glass beads for suppressing arcing therein | |
| GB2115603A (en) | Cathode-ray tube | |
| EP0196827B1 (en) | Colour cathode ray tube | |
| US2563474A (en) | Electron emissive cathode | |
| US3798477A (en) | Storage tube with target having conductive surface exposed through random cracks in dielectric coating | |
| KR100337869B1 (en) | Cathode ray tube | |
| TW522429B (en) | Color cathode ray tube having an improved electron gun electrode | |
| KR20060123640A (en) | Image display | |
| US5196764A (en) | Cathode ray tube having symmetrical anode potential | |
| JP2000502499A (en) | Method of manufacturing color cathode ray tube and color selection electrode | |
| Knoll et al. | Viewing storage tubes | |
| JP2589565B2 (en) | Cathode ray tube | |
| KR200159849Y1 (en) | Shadow mask of cathode ray tube | |
| KR950002052Y1 (en) | Metal back for crt | |
| KR0129777Y1 (en) | Un-stoppage power supply of cathode ray tube | |
| JPH0743934Y2 (en) | Flat light emitting device | |
| KR100689558B1 (en) | Electrode structure of field emission display | |
| JPH0326495B2 (en) |