EP0408139B1 - Display tube and deflection unit suitable for such a display tube - Google Patents
Display tube and deflection unit suitable for such a display tube Download PDFInfo
- Publication number
- EP0408139B1 EP0408139B1 EP19900201839 EP90201839A EP0408139B1 EP 0408139 B1 EP0408139 B1 EP 0408139B1 EP 19900201839 EP19900201839 EP 19900201839 EP 90201839 A EP90201839 A EP 90201839A EP 0408139 B1 EP0408139 B1 EP 0408139B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- field
- display tube
- guiding means
- deflection
- deflection coil
- 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 - Lifetime
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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
- H01J29/70—Arrangements for deflecting ray or beam
- H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
- H01J29/76—Deflecting by magnetic fields only
Definitions
- the invention relates to a display tube comprising a deflection unit having a carrier, a field deflection coil, a line deflection coil and field-guiding means.
- the invention further relates to a deflection unit which is suitable for such a display tube.
- Such a display tube can be used in black and white, colour and projection television, in data-display equipment and in other apparatuses in which a cathode ray tube is used.
- the deflection unit When the deflection unit is energized it deflects an electron beam generated in the display tube to form an image to be displayed.
- a display tube of the type described in the opening paragraph is characterized according to the invention in that the field-guiding means are provided in the deflection unit in a manner such that they produce little or no vibration.
- the invention is based on the insight that the occurrence of undesirable sound can be largely attributed to the fact that the fields generated when the deflection unit is energized cause the field-guiding means to vibrate in an undesirable manner. Said undesirable generation of sound is largely precluded by providing the field-guiding means in a little vibration producing manner according to the invention.
- a preferred embodiment of a display tube according to the invention is characterized in that the field-guiding means are secured on the carrier and encapsulated in electrically insulating material.
- the degree to which undesirable vibrations occur is very high. The reason for this being that the forces which are exerted on the field-guiding means when the deflection unit is energized can be so large that the carrier is made to vibrate via the field-guiding means.
- the carrier acts as a resonance box causing the undesirable sound to be intensified. The vibrations are damped to a sufficient degree by encapsulating the field-guiding means in electrically insulating material.
- the encapsulation of the field-guiding means takes place by filling the space around said field-guiding means with the electrically insulating material.
- said electrically insulating material is a curing synthetic resin.
- Polyurethane foam is particularly suitable because it can be provided in a simple manner.
- a further preferred embodiment of a display tube according to the invention is characterized in that the field-guiding means are secured to one of the deflection coils. Undesirable vibrations are precluded in that the field-guiding means are not secured to the carrier but to one of the deflection coils, for example the field deflection coil. As a result thereof, the carrier no longer acts as a resonance box.
- the fixation is preferably carried out using a rapidly curing adhesive, thus obtaining a fast and accurate fixation.
- a display tube which is characterized in that the field-guiding means comprise two soft magnetic elements which are arranged to produce little vibration, diametrally opposite each other between the field deflection coil and the line deflection coil, substantially parallel to the magnetic field of the field deflection coil, near the centre of the field deflection coil, exhibits an extremely low noise behaviour during the display of an image.
- the invention further relates to a deflection unit for a display tube, said deflection unit comprising a carrier, a field deflection coil, a line deflection coil and field-guiding means, and is characterized in that the field-guiding means are arranged in the deflection unit so as to produce little vibration.
- Fig. 1 is a longitudinal sectional view of a display tube 1 comprising a neck portion 2 in which an electron-gun system 3 is mounted, a conical enveloping portion 4 and a display window 5.
- a deflection unit 7 is mounted on the display tube 1 at the transition from the neck portion 2 to the enveloping portion 4.
- Said deflection unit 7 comprises a carrier 8 of electrically insulating material having a front end portion 9 and a rear end portion 10.
- a line deflection coil 11 on the inside of the carrier 8, for generating a (line) deflection field for deflecting electron beams produced by the electron-gun system 3 in the horizontal direction
- a field deflection coil 12 on the outside of the carrier 8, for generating a (field) deflection field in the vertical direction.
- Said deflection coils 11 and 12 are surrounded by an annular core 14 of ferromagnetic material.
- field-guiding means 15 are arranged between the field deflection coil 12 and the line deflection coil 11 by securing them to the carrier 8.
- the field-guiding means 15 are arranged so as to produce little vibration by encapsulating them in electrically insulating material 16.
- the material has to be electrically insulating to preclude a short-circuit between the field deflection coil and the line deflection coil. Vibrations, if any, are damped by said electrically insulating material 16.
- the invention applies, in particular, to field-guiding means 15 which serve to influence the deflection fields in such a manner that a satisfactory astigmatic level with a tolerably small coma can be realised (so-called astigmatism laminations).
- the space between the field deflection coil 12 and the line deflection coil 11 is filled with a curing synthetic resin 16 at the location of the field-guiding means 15, so that said field-guiding means 15 are efficiently arranged in a vibrationless manner (see Fig. 2).
- the field-guiding means are preferably formed by two soft magnetic elements 17 and 18 which are arranged diametrally opposite each other, substantially parallel to the magnetic field of the field deflection coil 12.
- the synthetic resin Before the synthetic resin has cured, it can be provided in the space between the field deflection coil and the line deflection coil in a simple manner.
- Polyurethane foam is particularly suitable.
- epoxy resins and suitable adhesives can alternatively be used as electrically insulating materials.
- the electrically insulating material 16 which surrounds the field-guiding means may have two functions. Firstly, it permits the field-guiding means to be secured in the deflection unit and, secondly, it damps any vibrations. As a result hereof, the occurrence of undesirable sounds in the display tube when an image is displayed is largely precluded.
- Fig. 3 is a diagrammatic longitudinal sectional view of a deflection unit 7 in which the field-guiding means 15 are secured directly on one of the deflection coils, in this case the line deflection coil 11.
- a rapidly curing adhesive for example a UV-curing adhesive is used to secure the field-guiding means to the line deflection coil 11.
- a rapidly curing adhesive for example a UV-curing adhesive is used to secure the field-guiding means to the line deflection coil 11.
- An additional advantage of securing the field-guiding means on the deflection coils is that in the case of vibrations the positioning of the field-guiding means and the deflection coils relative to each other does not change. Consequently, the electromagnetic fields generated remain unchanged when vibrations occur. Thus, an image to be displayed by the display tube is hardly adversely influenced as a result of undesirable shifts of field-guiding means and deflection coils.
Landscapes
- Details Of Television Scanning (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Description
- The invention relates to a display tube comprising a deflection unit having a carrier, a field deflection coil, a line deflection coil and field-guiding means.
- The invention further relates to a deflection unit which is suitable for such a display tube.
- Such a display tube can be used in black and white, colour and projection television, in data-display equipment and in other apparatuses in which a cathode ray tube is used.
- When the deflection unit is energized it deflects an electron beam generated in the display tube to form an image to be displayed.
- In some cases, however, it appears that during the display of an image the display tube brings about an undesirable sound which is irritating to the viewer.
- It is an object of the invention to provide, inter alia , a display tube in which the generation of undesirable sound during the operation of the tube is at least substantially prevented.
- For this purpose, a display tube of the type described in the opening paragraph is characterized according to the invention in that the field-guiding means are provided in the deflection unit in a manner such that they produce little or no vibration.
- The invention is based on the insight that the occurrence of undesirable sound can be largely attributed to the fact that the fields generated when the deflection unit is energized cause the field-guiding means to vibrate in an undesirable manner. Said undesirable generation of sound is largely precluded by providing the field-guiding means in a little vibration producing manner according to the invention.
- A preferred embodiment of a display tube according to the invention is characterized in that the field-guiding means are secured on the carrier and encapsulated in electrically insulating material. In particular when the field-guiding means are secured on the carrier, it appears that the degree to which undesirable vibrations occur is very high. The reason for this being that the forces which are exerted on the field-guiding means when the deflection unit is energized can be so large that the carrier is made to vibrate via the field-guiding means. The carrier acts as a resonance box causing the undesirable sound to be intensified. The vibrations are damped to a sufficient degree by encapsulating the field-guiding means in electrically insulating material.
- Preferably, the encapsulation of the field-guiding means takes place by filling the space around said field-guiding means with the electrically insulating material. Preferably, said electrically insulating material is a curing synthetic resin. Polyurethane foam is particularly suitable because it can be provided in a simple manner.
- A further preferred embodiment of a display tube according to the invention is characterized in that the field-guiding means are secured to one of the deflection coils. Undesirable vibrations are precluded in that the field-guiding means are not secured to the carrier but to one of the deflection coils, for example the field deflection coil. As a result thereof, the carrier no longer acts as a resonance box. The fixation is preferably carried out using a rapidly curing adhesive, thus obtaining a fast and accurate fixation.
- A display tube according to a further preferred embodiment of the invention, which is characterized in that the field-guiding means comprise two soft magnetic elements which are arranged to produce little vibration, diametrally opposite each other between the field deflection coil and the line deflection coil, substantially parallel to the magnetic field of the field deflection coil, near the centre of the field deflection coil, exhibits an extremely low noise behaviour during the display of an image.
- The invention further relates to a deflection unit for a display tube, said deflection unit comprising a carrier, a field deflection coil, a line deflection coil and field-guiding means, and is characterized in that the field-guiding means are arranged in the deflection unit so as to produce little vibration.
- These and other aspects of the invention will be described and explained by means of the drawing and the examples, in which
- Fig. 1 is a diagrammatic longitudinal sectional view of a display tube according to the invention having a deflection unit,
- Fig. 2 is a diagrammatic cross-sectional view of a display tube according to an alternative embodiment of the invention, and
- Fig. 3 is a diagrammatic longitudinal sectional view of a deflection unit according to the invention, in which the field-guiding means are provided on one of the deflection coils.
- Fig. 1 is a longitudinal sectional view of a
display tube 1 comprising a neck portion 2 in which an electron-gun system 3 is mounted, a conical enveloping portion 4 and adisplay window 5. Adeflection unit 7 is mounted on thedisplay tube 1 at the transition from the neck portion 2 to the enveloping portion 4. Saiddeflection unit 7 comprises acarrier 8 of electrically insulating material having afront end portion 9 and arear end portion 10. Between these end portions there are aline deflection coil 11, on the inside of thecarrier 8, for generating a (line) deflection field for deflecting electron beams produced by the electron-gun system 3 in the horizontal direction, and afield deflection coil 12, on the outside of thecarrier 8, for generating a (field) deflection field in the vertical direction. Saiddeflection coils annular core 14 of ferromagnetic material. - In this embodiment, field-guiding means 15 are arranged between the
field deflection coil 12 and theline deflection coil 11 by securing them to thecarrier 8. The field-guiding means 15 are arranged so as to produce little vibration by encapsulating them in electrically insulatingmaterial 16. The material has to be electrically insulating to preclude a short-circuit between the field deflection coil and the line deflection coil. Vibrations, if any, are damped by said electrically insulatingmaterial 16. - The invention applies, in particular, to field-guiding means 15 which serve to influence the deflection fields in such a manner that a satisfactory astigmatic level with a tolerably small coma can be realised (so-called astigmatism laminations).
- Preferably, the space between the
field deflection coil 12 and theline deflection coil 11 is filled with a curingsynthetic resin 16 at the location of the field-guidingmeans 15, so that said field-guidingmeans 15 are efficiently arranged in a vibrationless manner (see Fig. 2). As diagrammatically shown in Fig. 2, the field-guiding means are preferably formed by two softmagnetic elements field deflection coil 12. Before the synthetic resin has cured, it can be provided in the space between the field deflection coil and the line deflection coil in a simple manner. Polyurethane foam is particularly suitable. In addition, epoxy resins and suitable adhesives can alternatively be used as electrically insulating materials. Thus, the electrically insulatingmaterial 16 which surrounds the field-guiding means may have two functions. Firstly, it permits the field-guiding means to be secured in the deflection unit and, secondly, it damps any vibrations. As a result hereof, the occurrence of undesirable sounds in the display tube when an image is displayed is largely precluded. - Fig. 3 is a diagrammatic longitudinal sectional view of a
deflection unit 7 in which the field-guiding means 15 are secured directly on one of the deflection coils, in this case theline deflection coil 11. Preferably, a rapidly curing adhesive, for example a UV-curing adhesive is used to secure the field-guiding means to theline deflection coil 11. To enable the electromagnetic field to be influenced in a defined manner, it must be possible to rapidly fix an accurately adjusted position of the field-guiding means 15 relative to the deflection coils. This is achieved by the use of a rapidly curing adhesive. - The use of less rapidly curing adhesives is alternatively possible, but this implies that the field-guiding means have to be held in the desired position relative to the deflection coils for a longer period of time until the adhesive has cured and the position has been fixed.
- An additional advantage of securing the field-guiding means on the deflection coils is that in the case of vibrations the positioning of the field-guiding means and the deflection coils relative to each other does not change. Consequently, the electromagnetic fields generated remain unchanged when vibrations occur. Thus, an image to be displayed by the display tube is hardly adversely influenced as a result of undesirable shifts of field-guiding means and deflection coils.
Claims (9)
- A display tube comprising a deflection unit having a carrier, a field deflection coil, a line deflection coil and field-guiding means, characterized in that the field-guiding means are provided in the deflection unit in a manner such that they produce little or no vibration.
- A display tube as claimed in Claim 1, characterized in that the field-guiding means are secured on the carrier and encapsulated in electrically insulating material.
- A display tube as claimed in Claim 2, characterized in that the space around the field-guiding means is filled with the electrically insulating material.
- A display tube as claimed in Claim 2 or 3, characterized in that the electrically insulating material is a curing synthetic resin.
- A display tube as claimed in Claim 4, characterized in that the curing synthetic resin is polyurethane foam.
- A display tube as claimed in Claim 1, characterized in that the field-guiding means are secured on one of the deflection coils.
- A display tube as claimed in Claim 6, characterized in that the field-guiding means are secured to one of the deflection coils by means of a rapidly curing adhesive.
- A display tube as claimed in one of the preceding Claims, characterized in that the field-guiding means comprise two soft magnetic elements which are arranged to produce little vibration, diametrally opposite each other between the field deflection coil and the line deflection coil, substantially parallel to the magnetic field of the deflection coil, near the centre of the field deflection coil.
- A deflection unit suitable for a display tube as claimed in one of the preceding Claims, which deflection unit comprises a carrier, a field deflection coil, a line deflection coil and field-guiding means, characterized in that the field-guiding means are arranged in the deflection unit so as to produce little vibration.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL8901820 | 1989-07-14 | ||
NL8901820A NL8901820A (en) | 1989-07-14 | 1989-07-14 | CRT for TV or graphics display - has deflection assembly damped against vibration by insulated carrier |
NL9000373 | 1990-02-16 | ||
NL9000373A NL9000373A (en) | 1989-07-14 | 1990-02-16 | PICTURE TUBE AND DEFLECTOR SUITABLE FOR SUCH A PICTURE TUBE. |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0408139A2 EP0408139A2 (en) | 1991-01-16 |
EP0408139A3 EP0408139A3 (en) | 1991-09-11 |
EP0408139B1 true EP0408139B1 (en) | 1993-10-27 |
Family
ID=26646554
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19900201839 Expired - Lifetime EP0408139B1 (en) | 1989-07-14 | 1990-07-09 | Display tube and deflection unit suitable for such a display tube |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0408139B1 (en) |
JP (1) | JP3278692B2 (en) |
DE (1) | DE69004171T2 (en) |
NL (1) | NL9000373A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE1007166A3 (en) * | 1993-05-13 | 1995-04-11 | Philips Electronics Nv | TUBE WITH deflection. |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL8601803A (en) * | 1986-07-10 | 1988-02-01 | Philips Nv | COLOR IMAGE TUBE WITH ASTIGMATIC CORRECTIVE AGENTS. |
-
1990
- 1990-02-16 NL NL9000373A patent/NL9000373A/en not_active Application Discontinuation
- 1990-07-09 EP EP19900201839 patent/EP0408139B1/en not_active Expired - Lifetime
- 1990-07-09 DE DE1990604171 patent/DE69004171T2/en not_active Expired - Fee Related
- 1990-07-11 JP JP18169090A patent/JP3278692B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
DE69004171D1 (en) | 1993-12-02 |
DE69004171T2 (en) | 1994-05-05 |
EP0408139A2 (en) | 1991-01-16 |
EP0408139A3 (en) | 1991-09-11 |
JP3278692B2 (en) | 2002-04-30 |
NL9000373A (en) | 1991-02-01 |
JPH0346736A (en) | 1991-02-28 |
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