EP0601637B1 - Tube à rayons cathodiques muni d'une cathode semi-conductrice - Google Patents

Tube à rayons cathodiques muni d'une cathode semi-conductrice Download PDF

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Publication number
EP0601637B1
EP0601637B1 EP19930203356 EP93203356A EP0601637B1 EP 0601637 B1 EP0601637 B1 EP 0601637B1 EP 19930203356 EP19930203356 EP 19930203356 EP 93203356 A EP93203356 A EP 93203356A EP 0601637 B1 EP0601637 B1 EP 0601637B1
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EP
European Patent Office
Prior art keywords
ray tube
cathode
cathode ray
semiconductor
influencing
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
Application number
EP19930203356
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German (de)
English (en)
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EP0601637A1 (fr
Inventor
Evert C/O Int. Octrooibureau B.V. Seevinck
Tjerk Gerrit C/O Int. Octrooibureau B.V. Spanjer
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Koninklijke Philips NV
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Koninklijke Philips Electronics NV
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Priority to EP19930203356 priority Critical patent/EP0601637B1/fr
Publication of EP0601637A1 publication Critical patent/EP0601637A1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/308—Semiconductor cathodes, e.g. cathodes with PN junction layers
    • 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/04—Cathodes

Definitions

  • the invention relates to a cathode ray tube according to the introductory part of claim 1.
  • a cathode ray tube of this type, provided with a "cold cathode” is known from USP 4,303,930.
  • the semiconductor device which is a "cold cathode”
  • a pn junction is reverse-biased in such a way that there is avalanche multiplication of charge carriers. Some electrons may then acquire as much kinetic energy as is necessary for exceeding the electron work function.
  • the emission of these electrons is simplified by providing the semiconductor device with acceleration electrodes or gate electrodes on an insulating layer located on the main surface, which insulating layer leaves an aperture at the location of the emissive region. Emission is further simplified by providing the semiconductor surface at the location of the emissive region with a material reducing the work function such as, for example cesium.
  • connection wires of the substrate as well as the gate electrodes cannot, however, be considered as purely ohmic connections but have a given inductance. This results in a large voltage difference between the substrate and the gate electrode due to capacitive crosstalk between said grid and, for example, this substrate. This voltage difference is also dependent on the inductances of the connection wires, the resistance of, for example, the material of the gate electrode and the duration of the flashover. Usually, this difference is, however, so large that there may be a destructive breakdown of the insulating layer between the gate electrode and the subjacent substrate. As a result, cathode ray tubes comprising this type of cold cathodes are often rejected, notably during the spot-knocking process.
  • cathode ray tube according to the invention is characterized according to the characterizing part of claim 1.
  • the invention is based, inter alia on the recognition that the gate electrode with the subjacent insulating material and the semiconductor material can be considered to be components of a divided RC network.
  • a common connection via a high-ohmic resistor can be chosen so as to economize on the number of connections.
  • each cathode is preferably provided individually with the high-ohmic resistor which cathodes, if necessary, are connected via the same connection wire so as to reduce the number of connections. The resistors then realise a substantially complete decoupling between the different cathodes so that there is substantially no crosstalk.
  • the resistor forms part of a resistive network which is arranged on a support of ceramic material or glass on which the semiconductor cathodes are also arranged.
  • the resistive network may comprise a resistive voltage divider (so that voltage division occurs during use) with which the voltages at different gate electrodes can be set at different values. If necessary, such a resistive voltage divider may also be realised on the layer of insulating material, for example by means of resistors of polycrystalline silicon.
  • a semiconductor device for use in such a cathode ray tube is characterized in that the electrically insulating layer of the semiconductor body comprises a resistive voltage divider having tappings which are connected in a electrically conducting manner to connection wires of gate electrodes of the semiconductor cathode.
  • Fig. 1 shows diagrammatically a cathode ray tube 1 for picture display.
  • This tube has a display window 2, a cone 3 and a neck portion 4 with an end wall 5.
  • the neck portion 4 accommodates a plurality of (in this case 4) grid electrodes 8, 9, 10 and 12.
  • the cathode ray tube further has an anode 11 at the location of the display window and, if necessary, deflection electrodes. Further elements associated with such a cathode ray tube, such as deflection coils, shadow masks, etc . are omitted in Fig. 1 for the sake of simplicity.
  • the end wall 5 has leadthroughs 13 via which the connection wires for these elements are electrically interconnected to terminals 14.
  • the cathode ray tube is subjected to a process step known as spot-knocking so as to remove burrs and dust particles.
  • this process step for example grid 12 acquires a high voltage (approximately 40 kV) while the other grid electrodes are provided with pulsed or non-pulsed voltages of approximately 30 kV. Then flashovers may occur so that due to capacitive crosstalk between, for example the grid electrode 8 and the surface of the semiconductor body and gate electrodes provided on this body, voltage peaks of approximately 100 V to approximately 2 kV are generated on this surface and on the gate electrodes (also because the associated connection wire behaves as an inductance with respect to these voltage peaks at the rate at which they are generated).
  • the cathode is usually grounded while the electrodes 8, 9, 10 and 12 are maintained at voltages of 100 V, 2 kV, 8 kV and 30 kV, respectively. Such flashovers may occur also during this normal use, although the voltages at the acceleration electrodes do not necessarily occur in a rising sequence, as viewed from the cathode.
  • the semiconductor cathode comprises a gate electrode, as is described in USP 4,303,930, which is separated from the subjacent semiconductor surface by a insulating layer, there will easily be breakdown (the destructive breakdown voltage of such a layer may vary between approximately 200 V and approximately 300 V). Consequently, there may not only be a short-circuit between the gate electrode and the semiconductor body, but also silicon nitride which is associated with the insulating layer and is usually present to prevent absorption of cesium by silicon oxide may be attacked.
  • Fig. 2 shows diagrammatically a electrical substitution diagram of a part of the cathode ray tube with the grid 8 (also denoted as G 1 ) diagrammatically shown as a solid line and a semiconductor cathode whose substrate is shown by means of the solid line 15.
  • a gate electrode of, for example, polycrystalline silicon is present on the substrate and is separated from the substrate by an electrically insulating layer. This electrode is shown in Fig. 2 as a resistor divided into dividing resistors R.
  • the capacitance between the grid electrode 8 and the substrate is denoted by C 0 . Due to the resistive character of the gate electrode, the capacitance between the grid electrode 8 and this gate electrode may be considered to be a divided capacitance indicated by means of capacitances C 1 .
  • the capacitances C 2 represent a divided capacitance between the substrate and the gate electrode.
  • the inductances L denote the connection wires 24 (Fig. 1). For the sake of simplicity of the description, all these wires are connected to ground in Fig. 2.
  • Fig. 3 is a plan view and Fig. 4 is a cross-section taken on the line IV-IV in Fig. 3 of a practical embodiment of a cathode support provided with semiconductor cathodes for use in a cathode ray tube according to the invention.
  • Three cathodes 7R, 7G, 7B supplying the electron beams for the colours red, green and blue, respectively, are mounted on a support 6 of a ceramic material (aluminium oxide) or, for example glass.
  • Video signals 18R, 18G, 18B are applied to the cathodes via connection metallizations 19.
  • the beam currents are modulated via these video signals, for example by modulation of the avalanche current in a cathode as described in USP 4,303,930.
  • Gate or acceleration electrodes 22, 22' diagrammatically shown by means of rings in Fig. 3 are arranged around the actual emissive region 20 on an electrically insulating layer 21. If necessary, these electrodes may alternatively function as deflection electrodes and are made of, for example, polycrystalline silicon.
  • the further structure of the cathodes 7 is not further shown in Fig. 6 for the sake of simplicity. The cathodes are contacted at their lower sides via a metallization 28.
  • the gate electrodes 22, 22' are connected via diagrammatically shown bonding wires 23 to (terminals of) resistors 17, 17' which may be implemented as, for example, thin-film resistors; a material (for example, nickel chromium) which is conventionally used in the thin-film technology is chosen as a resistive material. Although these resistors are shown as discrete resistors in this case, they may alternatively be implemented as an uninterrupted layer of resistive material of a suitable shape.
  • the resistors 17, 17' have a resistance of 100 kOhm or more and are connected at their other terminals to common connection wires 24, 24', for example via connection metallization faces 123, 123'.
  • each cathode 7 has its own resistor 17 between the gate electrode 22 and the connection wire 22, mutual crosstalk between the cathodes is now considerably limited.
  • An interference signal at, for example the connection 18R is capacitively coupled through to the gate electrode 22 of cathode 7R via the capacitance between the semiconductor substrate in which the cathode is realised and the gate electrode.
  • Without the resistors 17 there would be a substantially ohmic connection between the gate electrodes 22 of the cathodes 7 so that the signal which has been coupled through would also influence the voltage at the gate electrodes 22.
  • Due to the presence of the high-ohmic resistors 17 a possibly occurring voltage peak at one of the gate electrodes 22 at the location of the common connection of the resistors 17 is already substantially eliminated so that said crosstalk has become negligible.
  • Fig. 5 shows diagrammatically a modification of the arrangement of Fig. 4 in which the cathode 7 is mounted at the lower side of the support 6 (for example, by means of flip-chip mounting) and the support is apertured for passing the beam at the location of the cathode 7.
  • the reference numerals in Fig. 5 further have the same significance as those in Fig. 4.
  • Fig. 6 shows another plan view in which the resistors 17, 17 a , 17 b , 17 constitute a voltage divider.
  • the mutual ratios between the resistors are chosen to be such that, dependent on the voltages at the terminals 26, 27, the tappings 29, 29', 29'' supply the correct voltages for the gate electrodes 22, 22', 22'' of the three cathodes 7R, 7G, 7B.
  • These tappings are connected to the gate electrodes via bonding wires 23 diagrammatically shown, in this example via metallization strips 30 provided on the support 6.
  • Fig. 7 is a diagrammatic plan view and Fig. 8 is a cross-section taken on the line VIII-VIII in Fig. 7 of a semiconductor device provided with such a resistive voltage divider. Fig. 8 also shows the structure of such a semiconductor device in greater detail than in the other examples.
  • the semiconductor cathode comprises a semiconductor body 31, in this example of silicon. It comprises at a main surface 32 of the semiconductor body an n-type surface region 33 which constitutes the pn junction 36 together with the p-type regions 34 and 35.
  • the p-type region 37 and hence the emissive region 20 are chosen to be annular in this example. By applying sufficiently high voltages in the reverse direction across the pn junction, electrons are generated due to avalanche multiplication, which electrons may be emitted from the semiconductor body.
  • the p-type region 35 is contacted at the lower side by a metal layer 38 in this example. This contact is preferably realised via a highly doped contact zone 37.
  • the donor concentration in the n-type region 33 at the surface is, for example 5.10 19 atoms/cm 3
  • the acceptor concentration in the p-type region 34 is much lower, for example 5.10 16 atom/cm 3 .
  • the semiconductor device is provided with a p-type region 35 of a higher doping, located within an aperture in the insulating layer 21 provided on the surface.
  • gate electrodes 22, 22' are arranged within the circular aperture 39 (and the consequently bare emissive part 20), while (also in a plan view) gate electrodes 22", 22"' are present outside this aperture.
  • a resistive strip 40 made of, for example polysilicon is present on the insulating layer 21.
  • the parts of the resistive strip denoted by braces now fulfil the same function as the resistors 17 a , 17 b in Fig. 6.
  • the resistors 17 may also be mounted on a support again.
  • connection wire 24 or a bonding wire, if the cathode is mounted on a support again
  • a high-ohmic resistor not shown

Landscapes

  • Cold Cathode And The Manufacture (AREA)

Claims (10)

  1. Tube à rayons cathodiques (10) comprenant au moins une cathode semi-conductrice (7) pour générer un faisceau d'électrons, ladite cathode comportant un substrat (15) et une surface principale (32) d'un corps de semi-conducteur (31) étant pourvue d'une couche isolante de l'électricité (21) présentant au moins une ouverture à l'endroit d'une zone émettrice d'électrons (20), et au moins une électrode (22) pour influencer le faisceau d'électrons émis, étant présente sur la couche isolante de l'électricité (21), caractérisé en ce que l'électrode (22) destinée à influencer les électrons émis est connectée à un fil de connexion (24) via une résistance (17) entre l'électrode (22) destinée à influencer les électrons émis et ledit fil de connexion (24), ladite résistance terminant le circuit RC divisé, formé par l'électrode (22) destinée à influencer les électrons émis et la couche isolante ainsi que le corps de semi-conducteur.
  2. Tube à rayons cathodiques (10) suivant la revendication 1, caractérisé en ce que la résistance (17) a une valeur ohmique qui est suffisamment élevée pour empêcher le claquage de la couche isolante dans un domaine de tension allant jusqu'à approximativement 2 kV.
  3. Tube à rayons cathodiques (10) suivant la revendications 1 ou 2, caractérisé en ce que la résistance (17) a une valeur ohmique d'au moins 100 kohms.
  4. Tube à rayons cathodiques (10) suivant les revendications 1, 2 ou 3, caractérisé en ce que l'électrode (22) destinée à influencer les électrons émis est une électrode de commande.
  5. Tube à rayons cathodiques (10) suivant les revendications 1 à 4, caractérisé en ce que la cathode semi-conductrice (7) et la résistance (17) sont présentes sur un support commun (6).
  6. Tube à rayons cathodiques (10) suivant l'une quelconque des revendications 1 à 5, caractérisé en ce qu'il comprend une pluralité de cathodes semi-conductrices (7), chaque cathode semi-conductrice étant connectée à un fil de connexion via une résistance séparée (17, 17').
  7. Tube à rayons cathodiques (10) suivant la revendication 6, caractérisé en ce que le fil de connexion (24) est commun aux résistances des différentes cathodes semi-conductrices (7).
  8. Tube à rayons cathodiques (10) suivant la revendication 6 ou 7, caractérisé en ce que le support commun (6) comprend un diviseur de tension à résistances (17, 17a, 17b) comportant des prises (29, 29', 29") qui sont connectées d'une manière conductrice de l'électricité à des électrodes (22, 22', 22") de la cathode semi-conductrice (7) pour influencer un faisceau émis.
  9. Tube à rayons cathodiques suivant la revendication 6 ou 7, caractérisé en ce qu'un diviseur de tension à résistances (17a, 17b, 17c) est présent sur la couche isolante de l'électricité (21) au niveau de la surface principale (23) du corps de semi-conducteur (31), ledit diviseur de tension à résistances comportant des prises qui sont connectées d'une manière conductrice de l'électricité à des électrodes (22, 22', 22", 22") de la cathode semi-conductrice (7) pour influencer un faisceau émis.
  10. Tube à rayons cathodiques suivant la revendication 9, caractérisé en ce que le diviseur de tension à résistances comprend une couche résistive de silicium polycristallin.
EP19930203356 1992-12-08 1993-12-01 Tube à rayons cathodiques muni d'une cathode semi-conductrice Expired - Lifetime EP0601637B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19930203356 EP0601637B1 (fr) 1992-12-08 1993-12-01 Tube à rayons cathodiques muni d'une cathode semi-conductrice

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP92203813 1992-12-08
EP92203813 1992-12-08
EP19930203356 EP0601637B1 (fr) 1992-12-08 1993-12-01 Tube à rayons cathodiques muni d'une cathode semi-conductrice

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EP0601637A1 EP0601637A1 (fr) 1994-06-15
EP0601637B1 true EP0601637B1 (fr) 1999-10-27

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Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19534228A1 (de) * 1995-09-15 1997-03-20 Licentia Gmbh Kathodenstrahlröhre mit einer Feldemissionskathode
TW365026B (en) * 1997-04-22 1999-07-21 Koninkl Philips Electronics Nv Semiconductor cathode and electron tube comprising a semiconductor cathode
DE69911012T2 (de) 1998-06-11 2004-06-17 Petr Viscor Flacher elektronenemitter

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736038A (en) * 1971-03-26 1973-05-29 Mitsubishi Kenki Kk Spot-knocking method for electronic tubes
NL184589C (nl) 1979-07-13 1989-09-01 Philips Nv Halfgeleiderinrichting voor het opwekken van een elektronenbundel en werkwijze voor het vervaardigen van een dergelijke halfgeleiderinrichting.
NL8104893A (nl) * 1981-10-29 1983-05-16 Philips Nv Kathodestraalbuis en halfgeleiderinrichting voor toepassing in een dergelijke kathodestraalbuis.

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