EP0427235A2 - Tube à rayons cathodiques en couleur et son procédé de commande - Google Patents
Tube à rayons cathodiques en couleur et son procédé de commande Download PDFInfo
- Publication number
- EP0427235A2 EP0427235A2 EP90121309A EP90121309A EP0427235A2 EP 0427235 A2 EP0427235 A2 EP 0427235A2 EP 90121309 A EP90121309 A EP 90121309A EP 90121309 A EP90121309 A EP 90121309A EP 0427235 A2 EP0427235 A2 EP 0427235A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- electron
- electron beams
- electron gun
- screen
- voltage
- 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.)
- Granted
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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
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/48—Electron guns
- H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
- H01J29/503—Three or more guns, the axes of which lay in a common plane
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/48—Electron guns
- H01J2229/4834—Electrical arrangements coupled to electrodes, e.g. potentials
- H01J2229/4837—Electrical arrangements coupled to electrodes, e.g. potentials characterised by the potentials applied
- H01J2229/4841—Dynamic potentials
Definitions
- a high-quality color cathode ray tube apparatus which is in general use is made up of a panel, a funnel continuous with the panel, and a cylindrical neck connected to the funnel.
- a phosphor screen having three kinds of light-emitting layers which correspond to red, blue and green colors, respectively, is formed on the inner side of the panel, and a shadow mask is arranged in such a manner as to face the phosphor screen.
- a frame by means of which the shadow mask is supported by the panel.
- An internal magnetic shield is attached to the frame.
- An external conductive layer is formed on the outer wall of the funnel, and an anode is provided on the selected portion of the funnel.
- the electron gun is of an in-line type, and three electron beams are emitted therefrom in a line (i.e., in parallel to one another).
- the electron gun includes: an electron beam-generating section GE which generates, controls and accelerates the electron beams; and a main electron lens section ML which converges and focuses the electron beams.
- the problem can be solved to a certain extent by improving either the electron gun or the deflection device.
- the improvement of the electron gun has been more effective in solving the problem than the improvement of the deflec tion device.
- a dynamic focus method has been used in the conventional apparatuses.
- the distortion of a beam spot is corrected by changing the power of the electron lens of the electron gun in synchronism with the deflection of the electron beams. If this method is used, the distor tion of a beam spot can be corrected in the peripheral portions of the screen.
- an object of the present invention is to provide a color cathode ray tube apparatus which is suitable for use in a high-quality TV system, is capable of producing a satisfactory image, with the deflection distortion being suppressed at every portion of the entire screen, and is very useful in practical application.
- Another object of the present invention is to provide a method for driving the color cathode ray tube apparatus mentioned above.
- the present invention provides a color cathode ray tube apparatus comprising: an envelope having a tube axis and made up of a panel, a funnel and a neck; a phosphor screen formed on the inner side of the panel., an electron gun assembly, received in the neck, for emitting electron beams of three kinds; deflection means, provided around the outer wall of that envelope portion which is located between the neck and the funnel, for horizontally and vertically deflecting the electron beams emitted from the electron gun assembly; and an operating voltage-applying device for applying a predetermined voltage to the electron gun assembly.
- the electron gun assembly of the apparatus includes a cathode, and a group of electrodes which jointly form one or more electron lenses. The power of these electron lenses changes in synchronism with the deflection of electron beams at different change rates during one scanning period.
- a resistor 90 is provided for the electron gun assembly 64.
- the resistor 90 has a first end 92 electrically connected to the sixth grid G6, a first intermediate portion 94 electrically connected to the intermediate electrode 82, a second intermediate portion electrically connected to the intermediate electrode 84, and a second end 98 which is the opposing end of the first end 92.
- An operating voltage-applying device 100 is electrically connected to the first end 92 of the resistor 90, and a variable resistor 102 is connected to the second end 98 of the resistor 90.
- a d.c. voltage of about 150V is applied to the cathode K, and a modulated signal corresponding to an image is supplied to the cathode K.
- the first grid G1 serves as a grounding grid
- the second grid G2 is applied with a voltage of about 600V
- the third and fifth grids G3 and G5 is applied with a voltage of about 7 KV
- the fourth grid G4 is connected to the second grid G2
- the sixth grid G6 is applied with an anode voltage which is as high as 25 to 30 KV.
- the first grid G5, the intermediate electrodes 82 and 84, and the sixth grid G6 jointly form a main lens.
- This main lens has a long focal length, and is generally referred to as an extended electric field lens because its lens region is expanded by the intermediate electrodes 82 and 84.
- the focusing voltage is applied to the electron gun assembly 64 by a dynamic focus circuit 103 by way of a diode element 104.
- the dynamic focus circuit 103 generates a voltage having a parabolic waveform.
- the diode element 104 is located between the dynamic focus circuit 103 and the third and fifth grids G3 and G5, and serves to clamp the parabolic waveform of the voltage generated by the dynamic focus circuit 103.
- a focusing voltage used in the present invention is compared with a focusing voltage used in a conventional apparatus, the former being indicated by the solid line B and the latter being indicated by the broken line A.
- the focusing voltage used in the conventional apparatus merely increases, just like a function of the second degree.
- the focusing voltage used in the present invention describes both a straight line and a curve of the second degree.
- beam spots are formed in the manner shown in Fig. 2. As is shown in this Figure, the beam spots formed in the center and nearly perphery of the screen are satisfactory in both size and shape.
- the beam spots formed in the mid region between the center and the periphery are larger than it without dynamic focusing, since the related focusing voltage is so high that the focusing force of the main lens becomes too weak.
- the beam spots formed at the periphery of the screen are distorted since the focusing force is too strong and the deflection distortion is not sufficiently eliminated.
- the beam spots indicated by the solid line B are applied, beam spots are formed in the manner shown in Fig. 7. As is shown in this Figure, the beam spots are comparatively satisfactory at each portion of the entire screen. More specifically, the beam spots formed in the screen region between the screen center and the screen periphery are not very large since the focusing voltage VD corresponding to that screen region is not increased very much. Further the beam spots formed at the screen periphery are neither large nor distorted since the focusing voltage VD corresponding to the screen periphery is increased.
- Fig. 8 is a graph showing the size of the electron beam spots formed in a 32-inch color cathode ray tube apparatus. More specifically, the graph in Fig. 8 shows how the diameter of an electron beam varies during a scanning operation from the screen center to the screen periphery, with the diameter of the beam spot formed in the screen center being represented by 1.0.
- the broken line A in the graph indicates relative values corresponding to the diameter of a beam spot formed when the focusing voltage used in the conventional apparatus is applied, i.e., when the focusing voltage indicated by the broken line A in Fig. 7 is applied.
- the solid line B in the graph indicates relative values corresponding to the diameter of a beam spot formed when the focusing voltage used in the present invention is applied.
- the power of the main lens of the electron gun assembly changes in accordance with the position at which an electron beam lands on the screen, because of the application of the focusing voltage shown in Fig. 5.
- the present invention is applied to the horizontal-deflection coil.
- the present invention is also applicable to the vertical-deflection coil.
- the focusing voltage may describe a linear line in the neighborhood of the screen center, describe a curve of the 2.5th degree between the screen center and the screen periphery, and describe a curve of the fourth degree in the neighborhood of the screen periphery.
- the focusing voltage may be changed at two or more change rates. With the focusing voltage being changed at a number of change rates, when the beam spot has more difficult deflection characteristic, the shape of the beam spot formed by an electron beam can be controlled in an optimal manner.
- a level-changeable voltage such as the focusing voltage mentioned above, can be obtained by use of rectangular pulses, such as those shown in Fig. 11A.
- the rectangular pulses shown in Fig. 11A can be easily generated by superimposing rectangular pulses A, B and C shown in Fig. 11B.
- Fig. 13 shows a color cathode ray tube apparatus according to the second embodiment of the present invention. Since the apparatus of the second embodiment differs from that of the first embodiment only in the type of operating voltage-applying device it employs, the same reference numerals will be used to denote the structural elements which are similar to those of the apparatus of the first embodiment.
- the electron gun assembly is driven by applying a dynamic voltage VD which changes in synchronism with deflection.
- the focusing voltage changes at two change rates, as in the first embodiment, but the two change rates are defined by a curve of the second degree and a curve of the third degree, respectively.
- the focusing voltage used in the second embodiment is similar to that men tioned above with reference to Fig. 9.
- the present invention is applied to the horizontal deflection coil, as in the first embodiment. Needless to say, the present invention is also applicable to the vertical deflection coil.
- the change rates of the focusing voltage used in the second embodiment need not be limited to those defined by curves of the second and third degrees; they may be defined by curves of the other degrees.
- the second electrode serving as an accelerating electrode is made up of three electrode elements.
- a voltage which changes in synchronism with deflection is applied to the central one of the three electrode elements.
- the inven tion of the Japanese reference may be similar to the present invention, in that a voltage which is synchronous with deflection is changed at a plurality of change rates in such a manner as to eliminate deflection distortion at the screen periphery.
- the first and second embodiments employ an electron gun assembly of an in-line type. Needless to say, however, this electron gun assembly may replaced with an electron gun assembly of a delta type, if so desired.
Landscapes
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28997089 | 1989-11-09 | ||
| JP289970/89 | 1989-11-09 | ||
| JP2272247A JPH03225733A (ja) | 1989-11-09 | 1990-10-12 | 陰極線管装置及びその駆動方法 |
| JP272247/90 | 1990-10-12 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0427235A2 true EP0427235A2 (fr) | 1991-05-15 |
| EP0427235A3 EP0427235A3 (en) | 1991-09-25 |
| EP0427235B1 EP0427235B1 (fr) | 1996-01-31 |
Family
ID=26550099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90121309A Expired - Lifetime EP0427235B1 (fr) | 1989-11-09 | 1990-11-07 | Tube à rayons cathodiques en couleur et son procédé de commande |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0427235B1 (fr) |
| DE (1) | DE69025126T2 (fr) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4742279A (en) * | 1986-01-21 | 1988-05-03 | U.S. Philips Corporation | Color display tube with reduced deflection defocussing |
| US4877998A (en) * | 1988-10-27 | 1989-10-31 | Rca Licensing Corp. | Color display system having an electron gun with dual electrode modulation |
-
1990
- 1990-11-07 EP EP90121309A patent/EP0427235B1/fr not_active Expired - Lifetime
- 1990-11-07 DE DE69025126T patent/DE69025126T2/de not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4742279A (en) * | 1986-01-21 | 1988-05-03 | U.S. Philips Corporation | Color display tube with reduced deflection defocussing |
| US4877998A (en) * | 1988-10-27 | 1989-10-31 | Rca Licensing Corp. | Color display system having an electron gun with dual electrode modulation |
Also Published As
| Publication number | Publication date |
|---|---|
| DE69025126T2 (de) | 1996-06-05 |
| EP0427235B1 (fr) | 1996-01-31 |
| DE69025126D1 (de) | 1996-03-14 |
| EP0427235A3 (en) | 1991-09-25 |
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