CA1224239A - Flat cathode ray tube - Google Patents
Flat cathode ray tubeInfo
- Publication number
- CA1224239A CA1224239A CA000477839A CA477839A CA1224239A CA 1224239 A CA1224239 A CA 1224239A CA 000477839 A CA000477839 A CA 000477839A CA 477839 A CA477839 A CA 477839A CA 1224239 A CA1224239 A CA 1224239A
- Authority
- CA
- Canada
- Prior art keywords
- cathode ray
- electron
- ray tube
- electrode array
- electron beam
- 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
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- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
Abstract
ABSTRACT:
A flat cathode ray tube having a micro-channel plate electron multiplier spaced a short distance from a fluorescent screen applied to a substantially flat face-plate. A deflection electrode array is disposed behind and spaced from the electron multiplier so as to he parallel therewith. An electron gun is disposed laterally of the space between the electron multiplier and the deflection electrode array so that in operation an electron beam produced by the electron gun enters the space along a path of movement substantially parallel to the deflection elec-trode array. Magnetic scanning means are provided to deflect the electron beam in a plane parallel to the deflec-tion electrode array. The magnetic scanning means enables a range of different screen shapes and sizes to be made without the risk of deflection defocusing at the edges of the screen and the deflection electrode array enables the depth of the tube envelope to be substantially independent of the screen size.
A flat cathode ray tube having a micro-channel plate electron multiplier spaced a short distance from a fluorescent screen applied to a substantially flat face-plate. A deflection electrode array is disposed behind and spaced from the electron multiplier so as to he parallel therewith. An electron gun is disposed laterally of the space between the electron multiplier and the deflection electrode array so that in operation an electron beam produced by the electron gun enters the space along a path of movement substantially parallel to the deflection elec-trode array. Magnetic scanning means are provided to deflect the electron beam in a plane parallel to the deflec-tion electrode array. The magnetic scanning means enables a range of different screen shapes and sizes to be made without the risk of deflection defocusing at the edges of the screen and the deflection electrode array enables the depth of the tube envelope to be substantially independent of the screen size.
Description
~.2~3~
FLAT CATHODE R~Y TUBE
The present inventlon relates to a flat cathode ray tube.
There have been many proposals for the deslgn of flat cathode ray tubes soma of which have been more practlcal than the others.
Generally these known proposals can be put lnto three classes.
Flrstly those ln whlch a repelllng field ls established between a transparent electrode carrled by a fluorescent screen and a rear electrode space therefrom and the electron beam is introduced along a tra~ectory which makes a constant acute angle with the fluorsscent screen. The electron beam under the influence of the repelllng field follows a parabolic tra~ectory to strike the fluorescent screen at a substaneially constant angle. The range of the beam is determined by the strength of the repelling field which can be varied by altering the voltage applied to the rear electrode. Such a type of cathode ray tube is disclosed in British Patent Speclfication 865667. One drawback to such a proposal tube is that the larger the fluorescent screen size, the greater the depth of the s,pace between the fluorescent screen and the rear electrode. Another drawback ls that the electron beam enters the repelling fleld with its final energy, for example 15keV and a large repelling field is required which has to be varied a~ frame or line frequency.
Secondly there is the type of cathode ray tube in which the electron beam enters laterally into an electrostatlc field between two spaced apart electrodes one of which is carrled by a fluorescent screen, which ~n certain cases ls provided on a rear wall of an envelope, whilst the other electrode is transparent and ls prov~ded on the faceplate. The electron beam is introduced laterally into tbe electrostatic field by a pair of deflection plates, the voltage applied to them being varied at frame rates to alter the angle of entry into the electrostatic field and thereby the range. This operation may bs regarded as lobbing the electron beam into the electrostatic field. Examples of this type of cathode ray tube are disclosed in 8riti~h Patent Specifications :~2~423~
FLAT CATHODE R~Y TUBE
The present inventlon relates to a flat cathode ray tube.
There have been many proposals for the deslgn of flat cathode ray tubes soma of which have been more practlcal than the others.
Generally these known proposals can be put lnto three classes.
Flrstly those ln whlch a repelllng field ls established between a transparent electrode carrled by a fluorescent screen and a rear electrode space therefrom and the electron beam is introduced along a tra~ectory which makes a constant acute angle with the fluorsscent screen. The electron beam under the influence of the repelllng field follows a parabolic tra~ectory to strike the fluorescent screen at a substaneially constant angle. The range of the beam is determined by the strength of the repelling field which can be varied by altering the voltage applied to the rear electrode. Such a type of cathode ray tube is disclosed in British Patent Speclfication 865667. One drawback to such a proposal tube is that the larger the fluorescent screen size, the greater the depth of the s,pace between the fluorescent screen and the rear electrode. Another drawback ls that the electron beam enters the repelling fleld with its final energy, for example 15keV and a large repelling field is required which has to be varied a~ frame or line frequency.
Secondly there is the type of cathode ray tube in which the electron beam enters laterally into an electrostatlc field between two spaced apart electrodes one of which is carrled by a fluorescent screen, which ~n certain cases ls provided on a rear wall of an envelope, whilst the other electrode is transparent and ls prov~ded on the faceplate. The electron beam is introduced laterally into tbe electrostatic field by a pair of deflection plates, the voltage applied to them being varied at frame rates to alter the angle of entry into the electrostatic field and thereby the range. This operation may bs regarded as lobbing the electron beam into the electrostatic field. Examples of this type of cathode ray tube are disclosed in 8riti~h Patent Specifications :~2~423~
2 PHB 3305~
1592571 and 2071402 and Speclfication W0 83/00406. These display tubes suffer from the same drawbacks as the first type of cathode ray tubes.
Thirdly there is the type of cathode ray tube in which the electron beam is produced by an electron gun mounted behind a screen with lts axis parallel to the plane of the screen. The electron beam produced undergoes llne scanning after lt has left the electron gun. Thereafter it ls reflected through 1~0 before being deflected towards the fluorescent screen. This type of lD display tube is disclosed in British Patent Specification 739~96.
In a variation of this type of cathode ray tube it i6 known from British Patent Specification 2101396A to provide an electron multiplier adjacent to, but spaced from, the fluorescent screen.
This has the advantage that the scanning and deflection of the electron beam can be separated from producing a light output from the cathode ray tube. In both these known proposals the scanning o~ the electron beam as it leaves the electron gun is done electrostatically using deflection plates which are inclined relative to each other. Further experimental work has shown that there can be a limitation on the length of a llne which can be scanned becaus~ deflection defocusslng is introduced by the scanning syste~ causing poor edge resolution. Such poor edge resolution can~ot be tolerated in datagraphic and instrument cathode ray tubes whlch frequently have different aspect ratios for ehe display area to that ratio of 4:3 used for television display.
The deflection defocussing is due to the maximum scan angle not being great enough to keep the beam spot in focus over the desired display area, the scan angle having to change depsnding on the throw of the electron beam from the electron gun.
It is an ob~ect of the present invention ~o provide a flat cathode ray tu'be in which the envelope thickness is subs~antially independent of screen size and in which the maximum scan angle is such that greater line lengths, relative to frame height, are obtainable.
According to the p~esent invention there is provided
1592571 and 2071402 and Speclfication W0 83/00406. These display tubes suffer from the same drawbacks as the first type of cathode ray tubes.
Thirdly there is the type of cathode ray tube in which the electron beam is produced by an electron gun mounted behind a screen with lts axis parallel to the plane of the screen. The electron beam produced undergoes llne scanning after lt has left the electron gun. Thereafter it ls reflected through 1~0 before being deflected towards the fluorescent screen. This type of lD display tube is disclosed in British Patent Specification 739~96.
In a variation of this type of cathode ray tube it i6 known from British Patent Specification 2101396A to provide an electron multiplier adjacent to, but spaced from, the fluorescent screen.
This has the advantage that the scanning and deflection of the electron beam can be separated from producing a light output from the cathode ray tube. In both these known proposals the scanning o~ the electron beam as it leaves the electron gun is done electrostatically using deflection plates which are inclined relative to each other. Further experimental work has shown that there can be a limitation on the length of a llne which can be scanned becaus~ deflection defocusslng is introduced by the scanning syste~ causing poor edge resolution. Such poor edge resolution can~ot be tolerated in datagraphic and instrument cathode ray tubes whlch frequently have different aspect ratios for ehe display area to that ratio of 4:3 used for television display.
The deflection defocussing is due to the maximum scan angle not being great enough to keep the beam spot in focus over the desired display area, the scan angle having to change depsnding on the throw of the electron beam from the electron gun.
It is an ob~ect of the present invention ~o provide a flat cathode ray tu'be in which the envelope thickness is subs~antially independent of screen size and in which the maximum scan angle is such that greater line lengths, relative to frame height, are obtainable.
According to the p~esent invention there is provided
3 PHB 33054 a flat cathode ray tube having an envelope wieh a substantiall~
planar faceplate and a rear wall opposite to, and spaced from, sald faceplate, and, within the envelope, a fluorescent screen on the inside of the faceplate, an electron multiplier dispoRed substantially parallel to, but spaced from, ~he faceplate, a deflection electrode array disposed adjacent a rear wall of the envelope, opposite the faceplate, said deflection electrode array being substantially parallel to and co-extensive with the elertron Lultiplier, means for producing an electron beam, said means being disposed laterally of a space formed between the electron multiplier ansl the deflection electrode array, said means in use introducing an electron beam into said space in a direction substantially parallel to the deflection electrode array, magnetic means disposed downstream of the path of movement of the electron beam for deflecting the electron beam laterally of its path of movement from the electron gun and means for connecting the electrodes of the deflection electrode array to a sourca o~
deflection voltages whereby in response to said deflection voltages the electron ~eam is deflected towards the electron multiplier.
Compared with the known proposals for cathode ray tubes described above, the cathode ray tube used in the apparatus made in accordance with the present invention has the advantages of having s~bstantially the same envelope thickness for a range screen size and also a greater maximum scan angle than is obtainable with electrostatic beam deflectors thereby enabling a wider variety of screen shapes to be made without the problem of de~lection defocussing causing poor edge resolution. Further by using an electron multiplier, particularly a micro-channel plate elec~ron multipller, a high resolution image is obtainable on the fluorescent screen and also the addressing of the electron multiplier cal~ be carried out using a low voltage, low current electron beam, The present lnvention will now be described, by way o~
example, wlth reference to the accompanying drawings, whereia:
Figure 1 is a perspective view, partly broken away, of a cathode ray tube made in accordance with the present inventlon, 3~3
planar faceplate and a rear wall opposite to, and spaced from, sald faceplate, and, within the envelope, a fluorescent screen on the inside of the faceplate, an electron multiplier dispoRed substantially parallel to, but spaced from, ~he faceplate, a deflection electrode array disposed adjacent a rear wall of the envelope, opposite the faceplate, said deflection electrode array being substantially parallel to and co-extensive with the elertron Lultiplier, means for producing an electron beam, said means being disposed laterally of a space formed between the electron multiplier ansl the deflection electrode array, said means in use introducing an electron beam into said space in a direction substantially parallel to the deflection electrode array, magnetic means disposed downstream of the path of movement of the electron beam for deflecting the electron beam laterally of its path of movement from the electron gun and means for connecting the electrodes of the deflection electrode array to a sourca o~
deflection voltages whereby in response to said deflection voltages the electron ~eam is deflected towards the electron multiplier.
Compared with the known proposals for cathode ray tubes described above, the cathode ray tube used in the apparatus made in accordance with the present invention has the advantages of having s~bstantially the same envelope thickness for a range screen size and also a greater maximum scan angle than is obtainable with electrostatic beam deflectors thereby enabling a wider variety of screen shapes to be made without the problem of de~lection defocussing causing poor edge resolution. Further by using an electron multiplier, particularly a micro-channel plate elec~ron multipller, a high resolution image is obtainable on the fluorescent screen and also the addressing of the electron multiplier cal~ be carried out using a low voltage, low current electron beam, The present lnvention will now be described, by way o~
example, wlth reference to the accompanying drawings, whereia:
Figure 1 is a perspective view, partly broken away, of a cathode ray tube made in accordance with the present inventlon, 3~3
4 PHB 33054 Figure 2 Ls a plan view of the cathode ray tube shown in Figure 1, and Figure 3 is a diagrammatic cross sectional view along the longitudinal a:~ls of the cathode ray tube shown in Figure 1.
The cathode ray tube 10 comprisei an envelope formed essentially of three parts: a generally box-like display section 12, a cylindrical neck 14 and and a divergent &ection, hereinafter termed a fan 16, connecting the neck 14 to an edge wall 18 of the display section 12. The display ~ection 12 comprises a substantlally planar, optically transparent faceplate 20, a substantially planar rear wall 22 (Figure 3) which is parallel to the faceplate 20 and edge walls interconnecting the faceplate 20 and the rear wall 22.
A fluorescent screen 24 is provided on the internal surface of the faceplate 20. A mlcro-channel plate electron multipl~er 26 is mounted within the dlsplay section 12 so that it is parallel to, and co-extensive with, the faceplate 20. A deflection electrode array 28 is provided either on the rear wall 22 if it is of an electrically insulating material or on an electrically insulating substrate which is carried by the rear wall 22. The electrode array 28 comprises a plurality of separate, generally elongate electrodes 30 which may be straight or curved. Electrical connections to the electrodes 30, the electron multiplier 26 and to a transparent electrode on the faceplate 20 are brought out of the envelope via connectors or lead-throughs 32, 34 in ~he edge wall 18.
An electron gun 36 ls provided in ehe neck 14 and is arranged ~ so that its longitudinal axis coincides with the plane of symmetry extending through the thickness of the envelope. The fan 16 has substantially flat upper and lower surfaces with the lower surface being arranged to be co-extensive with the rear wall 22. The cross-sectional height of the fan 16 is less than that of the display section 12. ConAequently the electron beam 38 eme!rges from the electron gun 36 on a path of movement which is closer ~o the deflection electrode array 28 than the electron multiplier 26. The 3~
depth of a space 40 between the electron multiplier 26 an~l the deflection electrode array 28 is such that the electron b~am 38 can be turned from a path of movement parallel to the def].ection electrode array 28 to approach the electron multiplier 26 at a substantially constant angle under the influence of the flelds produced betwsen the electrodes 30 and the electron multiplier 26.
Thus irrespective of the length of the throw of the electron beam 38 from the electron gun 36 the depth of the space 40 remalns same.
Scanning coils 42 are provided on the outside of the envelope at the neck-fan transition. As indicated in Figure 2 in l:he case of a square display area of say 125mm by 125mm, the deflet:tion angle for the electron beam to reach the corners furthest from the electron gun 36 i~ 37 whilst that to reach the nearest corners is 90. In consequence in use of the cathode ray tube 10 the deflection angle varies from 0 to 90 and at the same time the beam spot size at the input to the electron multiplier 26 has to be substantially constant. This has been found possible by using electromagnetic scanning, rather than elec.rostatic scanning, and providing focusing modulation for the electron spot and keystone correction for the raster.
In operation a low voltage, low current electron beaDI 38 is produced by the electron gun 36 which has a final anode voltage of +400V relative to the cathode voltage (for example OV). The electron beam 38 undergoes line scanning by mean~ of appropriate currents through the scan coils 42.
The inpu~ side of the electron multiplier 26 is at a voltage corresponding to the final anode voltage of the electron gun (+40 W 3 and the voltage applied to the output side is lkV greater.
Finally the voltage applied to the electron on the fluorescent screen is of the order of lOkV higher than that applied to the output side of the electron multiplier 26. Suitably the electrodes 30 of the electrode array 28 are at OV so that the electron beam 38 enters a repelling field causing it to be deflected towards the nearer edge of the fluorescent screen. Beginning with the electrode 30 nearest the electron gun 36, its voltage is :lncreased ~2~4~3~
substantially linearly to -~400V so that a field free space i5 produced through which the tra~ectory of the electron beam 38 passes substantially undisturbed until it reache~ the repelllng field which causes it to be deflected towards the electron multiplier 26. In order to produce a substantlally linear scan, it is arranged that when the voltage of one of the electrodes 30 i8 approximately half the final voltage that is +400V in this example3 then the voltage applied to the next electrode 3() in the array 28 is increased at the same rate and so on.
Obvlously if it is desired to deflect the electron beam in the opposite direction, then all but the two mose distant elec~rodes 30 from the electron gun 36 which are respectively a~ OV and ~200V, are initially at ~400V and then in reverse sequence the voltages on the electrodes are progressively reduced to OV in turn.
In variant of the illustrated cathode ray tube arrangement, the externally mounted acan coils 42 are replaced by internally arranged pole pieces and/or deflection coils.
The number of electrodes 30 in the array 28 is a compromise between the acceptable thlckness of the tube and the number of the frame scan voltage generators required. By way of example for a screen si~e of 125mm by 12~mm the tube thickness could be reduced to 25mm if twe~ty-one electrodes were used or alternatively if the number of electrodes is of the order of seven then the th~ckness would be of the order of 40mm.
If it is desired to produce a coloured display for datagraphic and instrumentltion purposes then this can be achieved by making the fluorescent screen 24 from a penetron phosphor. Different colours are prcduced by suitably varying the voltage applied to the transparent electrode on the faceplate 20, the voltage on the output side of the electron multiplier 26 being held constant.
The cathode ray tube 10 comprisei an envelope formed essentially of three parts: a generally box-like display section 12, a cylindrical neck 14 and and a divergent &ection, hereinafter termed a fan 16, connecting the neck 14 to an edge wall 18 of the display section 12. The display ~ection 12 comprises a substantlally planar, optically transparent faceplate 20, a substantially planar rear wall 22 (Figure 3) which is parallel to the faceplate 20 and edge walls interconnecting the faceplate 20 and the rear wall 22.
A fluorescent screen 24 is provided on the internal surface of the faceplate 20. A mlcro-channel plate electron multipl~er 26 is mounted within the dlsplay section 12 so that it is parallel to, and co-extensive with, the faceplate 20. A deflection electrode array 28 is provided either on the rear wall 22 if it is of an electrically insulating material or on an electrically insulating substrate which is carried by the rear wall 22. The electrode array 28 comprises a plurality of separate, generally elongate electrodes 30 which may be straight or curved. Electrical connections to the electrodes 30, the electron multiplier 26 and to a transparent electrode on the faceplate 20 are brought out of the envelope via connectors or lead-throughs 32, 34 in ~he edge wall 18.
An electron gun 36 ls provided in ehe neck 14 and is arranged ~ so that its longitudinal axis coincides with the plane of symmetry extending through the thickness of the envelope. The fan 16 has substantially flat upper and lower surfaces with the lower surface being arranged to be co-extensive with the rear wall 22. The cross-sectional height of the fan 16 is less than that of the display section 12. ConAequently the electron beam 38 eme!rges from the electron gun 36 on a path of movement which is closer ~o the deflection electrode array 28 than the electron multiplier 26. The 3~
depth of a space 40 between the electron multiplier 26 an~l the deflection electrode array 28 is such that the electron b~am 38 can be turned from a path of movement parallel to the def].ection electrode array 28 to approach the electron multiplier 26 at a substantially constant angle under the influence of the flelds produced betwsen the electrodes 30 and the electron multiplier 26.
Thus irrespective of the length of the throw of the electron beam 38 from the electron gun 36 the depth of the space 40 remalns same.
Scanning coils 42 are provided on the outside of the envelope at the neck-fan transition. As indicated in Figure 2 in l:he case of a square display area of say 125mm by 125mm, the deflet:tion angle for the electron beam to reach the corners furthest from the electron gun 36 i~ 37 whilst that to reach the nearest corners is 90. In consequence in use of the cathode ray tube 10 the deflection angle varies from 0 to 90 and at the same time the beam spot size at the input to the electron multiplier 26 has to be substantially constant. This has been found possible by using electromagnetic scanning, rather than elec.rostatic scanning, and providing focusing modulation for the electron spot and keystone correction for the raster.
In operation a low voltage, low current electron beaDI 38 is produced by the electron gun 36 which has a final anode voltage of +400V relative to the cathode voltage (for example OV). The electron beam 38 undergoes line scanning by mean~ of appropriate currents through the scan coils 42.
The inpu~ side of the electron multiplier 26 is at a voltage corresponding to the final anode voltage of the electron gun (+40 W 3 and the voltage applied to the output side is lkV greater.
Finally the voltage applied to the electron on the fluorescent screen is of the order of lOkV higher than that applied to the output side of the electron multiplier 26. Suitably the electrodes 30 of the electrode array 28 are at OV so that the electron beam 38 enters a repelling field causing it to be deflected towards the nearer edge of the fluorescent screen. Beginning with the electrode 30 nearest the electron gun 36, its voltage is :lncreased ~2~4~3~
substantially linearly to -~400V so that a field free space i5 produced through which the tra~ectory of the electron beam 38 passes substantially undisturbed until it reache~ the repelllng field which causes it to be deflected towards the electron multiplier 26. In order to produce a substantlally linear scan, it is arranged that when the voltage of one of the electrodes 30 i8 approximately half the final voltage that is +400V in this example3 then the voltage applied to the next electrode 3() in the array 28 is increased at the same rate and so on.
Obvlously if it is desired to deflect the electron beam in the opposite direction, then all but the two mose distant elec~rodes 30 from the electron gun 36 which are respectively a~ OV and ~200V, are initially at ~400V and then in reverse sequence the voltages on the electrodes are progressively reduced to OV in turn.
In variant of the illustrated cathode ray tube arrangement, the externally mounted acan coils 42 are replaced by internally arranged pole pieces and/or deflection coils.
The number of electrodes 30 in the array 28 is a compromise between the acceptable thlckness of the tube and the number of the frame scan voltage generators required. By way of example for a screen si~e of 125mm by 12~mm the tube thickness could be reduced to 25mm if twe~ty-one electrodes were used or alternatively if the number of electrodes is of the order of seven then the th~ckness would be of the order of 40mm.
If it is desired to produce a coloured display for datagraphic and instrumentltion purposes then this can be achieved by making the fluorescent screen 24 from a penetron phosphor. Different colours are prcduced by suitably varying the voltage applied to the transparent electrode on the faceplate 20, the voltage on the output side of the electron multiplier 26 being held constant.
Claims (8)
1. A flat cathode ray tube having an envelope including a substantially planar faceplate and a rear wall opposite to, and spaced from, said faceplate and within the envelope, a fluorescent screen on the inside of said faceplate, a channel plate electron multiplier disposed substantially parallel to, but spaced from, said faceplate, a deflection electrode array disposed adjacent said rear wall, said deflection electrode array being substantially parallel to and co-extensive with the electron multiplier, means for producing an electron beam, said means being dis-posed laterally of a space formed between the electron multiplier and the deflection electrode array said means in use introducing an electron beam into said space along a path substantially parallel to the deflection electrode array, magnetic deflection means disposed downstream of the elec-tron beam producing means adjacent the path of the electron beam for deflecting the electron beam laterally of its path of movement from the electron beam producing means and means for connecting the electrodes of the deflection electrode array to a source of deflection voltages for effecting deflection of the electron beam towards the electron multi-plier
2. A cathode ray tube as claimed in Claim 1, where-in the magnetic means comprises coils mounted on the out-side of the envelope.
3. A cathode ray tube as claimed in Claim 1, where-in the magnetic means are disposed within the envelope.
4. A cathode ray tube as claimed in Claim 1, where-in the fluorescent screen is square.
5. A cathode ray tube as claimed in Claim 1, where-in the envelope comprises a laterally extending neck con-taining the electron beam producing means and wherein the longitudinal axis of the electron gun is closer to the deflection electrode array than the fluorescent screen.
6. A cathode ray tube as claimed in Claim 5, where-in a portion of the envelope containing the screen is of rectilinear shape and the neck is coupled to an edge of said envelope portion by a divergent section.
7. A cathode ray tube as claimed in Claim 6, where-in said magnetic means are disposed in the vicinity of a junction of the neck and the divergent section.
8. A cathode ray tube as claimed in Claim 1, where-in the fluorescent screen comprises a penetration type of phosphor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000477839A CA1224239A (en) | 1985-03-28 | 1985-03-28 | Flat cathode ray tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000477839A CA1224239A (en) | 1985-03-28 | 1985-03-28 | Flat cathode ray tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1224239A true CA1224239A (en) | 1987-07-14 |
Family
ID=4130145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000477839A Expired CA1224239A (en) | 1985-03-28 | 1985-03-28 | Flat cathode ray tube |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1224239A (en) |
-
1985
- 1985-03-28 CA CA000477839A patent/CA1224239A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |