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
  • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
  • H01J29/06—Screens for shielding; Masks interposed in the electron stream
  • H01J29/07—Shadow masks for colour television tubes
  • H01J29/073—Mounting arrangements associated with shadow masks
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2229/00—Details of cathode ray tubes or electron beam tubes
  • H01J2229/07—Shadow masks
  • H01J2229/0705—Mounting arrangement of assembly to vessel
  • H01J2229/0711—Spring and plate (clip) type

Definitions

• the present invention relates to a color cathode ray tube having a substantially flat screen, and more precisely to the device for holding a frame / mask for color selection assembly fitted to such a tube.
• the invention finds its application in any type of tube comprising a mask for selecting colors, and is also well suited to tubes, the mask of which is produced by stamping and is held in place inside the tube by a rigid frame on which it is secured to the tubes whose mask is stretched in at least one direction and kept in tension by fixing on at least one pair of opposite sides of the frame.
• a conventional color cathode ray tube is composed of a vacuum glass envelope.
• the tube has, inside the envelope, a color selection mask located at a precise distance from the glass front face of the tube, front face on which are deposited arrays of red, green and blue phosphors to form a screen.
• An electromagnetic deflection device generally placed outside the tube and close to the electron gun, has the function of deflecting the electron beams in order to make them scan the surface of the panel on which the phosphor networks are arranged. Under the influence of three electron beams each corresponding to a specific primary color, the phosphor networks allow the reproduction of color images on the screen, the mask allowing each determined beam to illuminate only the luminophore of the color. corresponding.
• the color selection mask must be placed and maintained during the operation of the tube in a precise position inside the tube. The mask maintenance functions are carried out thanks to
• the frame / mask assembly is suspended in the front face of the tube by means of elastic support means secured to the frame and cooperating with the pins inserted in the glass wall of the tube.
• the support means must have sufficient elasticity to allow the frame / mask assembly to be disassembled several times from the front face during the various phases of the phosphor network manufacturing process.
• the support means are generally arranged either in the middle of the sides of the frame, as illustrated by patent US4528475 or at the corners of said frame as illustrated for example by patent EP207724; In all cases, given the large number of operations for inserting and removing the frame / mask assembly relative to the front face, it may result that the final position of said assembly, and therefore of the mask relative to the phosphor screen, or slightly offset from said screen. This offset causes discoloration of the images by the fact that the mask is not at the right distance from the screen. Furthermore, in the case of a tube whose appearance of the screen is yaws, the radii of curvature defining the surface of the mask are large values.
• the mask then becomes very sensitive to external vibrations; under the influence of shock or external mechanical vibrations, for example acoustic vibrations due to the loudspeakers of the television set in which the tube is inserted; the mask can then enter into vibration according to its natural frequency of resonance.
• the vibrations of the mask have the effect of modifying the landing zone of the electron beams on the screen of the tube, the points of impact of each beam then being offset with respect to the associated phosphor network, thus creating a discoloration of the image reproduced on the screen.
• the invention provides a support structure for the frame / mask assembly offering good elasticity and which is not very sensitive to shock and vibrations to best guarantee the required distance between the mask and the phosphor screen.
• the color cathode ray tube comprises: - a substantially rectangular front face on the internal surface of which a luminescent screen is deposited, - a color selection mask placed facing the luminescent screen, said mask being secured to a substantially rectangular frame, comprising a pair of long sides and a pair of short sides, - elastic support means for the frame / mask assembly inside the tube, at least one of these support means comprising a first metallic member comprising an elastic central part, a first end portion comprising an orifice intended to engage around a pin integral with the front face of the tube, and a second end portion attached by welding directly or indirectly to the frame, characterized in that the welding is carried out on the surface of the second end portion in at least two distinct zones arranged with so as to form with the orifice of the first end portion an acute angle ⁇ greater than 10 °.
• FIG. 1 illustrates a section of a cathode ray tube with color selection mask along the longitudinal axis
• Figure 2 shows means for supporting a frame / mask assembly according to the prior art
• Figure 3 illustrates a first embodiment according to the present invention
• Figure 4 illustrates a second embodiment of the present invention
• Figures 5a and 5b illustrate an alternative embodiment of the present invention, respectively by a front view and in section.
• FIG. 1 shows a cathode ray tube 1 composed of a vacuum envelope 2 comprising a substantially rectangular front face 3 and a funnel-shaped rear part 4 ending in a cylindrical neck 5.
• the front face is defined from a horizontal axis X, parallel to its largest dimension, and a vertical axis Y, parallel to its smallest dimension; the axes X and Y intersect at the center of the front face and are perpendicular to the main longitudinal axis Z which passes through the center of the cylindrical neck 5 and through the center of the front face 3.
• a screen 6 of luminescent materials On the internal part of the front face 3 is deposited a screen 6 of luminescent materials, the latter being excited by the scanning of the electron beams 7 coming from an electron gun 8 disposed in the neck of the tube.
• the scanning of the electron beams is carried out by a magnetic deflection device 12 disposed on the neck of the tube.
• a color selection mask 9 comprising a perforated surface 10, substantially parallel to the surface of the screen 6, and a skirt 11, folded in a direction substantially parallel to the longitudinal axis Z.
• a frame 20, of L-shaped section is mounted inside the glass envelope so as to position the mask at a precise distance from the luminescent screen.
• the frame has a flange 21 which extends practically in a direction parallel to the axis Z.
• the skirt 11 of the mask is placed inside the frame and spot welded to the flange 21.
• FIG. 2 illustrates a structure of support means 100 according to the state of the art.
• This support is produced for example from an elongated metal plate, comprising an elastic central part 101, a first end 102 of which is provided with an opening 106 intended to come engage around pin 13 of the glass envelope; the metal plate 100 has a second end 103 folded so that its surface can be welded, for example at two points 104 and 105 on the flange of the frame.
• the support according to this structure is advantageously secured in the middle of the sides of the frame, the weld points 104 and 105 being substantially aligned with the opening 106.
• the metal plate 101 can be formed by a single type of alloy, for example stainless steel, or by a bimetal intended to compensate in a known manner for the transient movements of the frame / mask assembly due to the thermal behavior of said assembly when the tube is put into operation.
• this type of support structure may not offer sufficient mechanical rigidity, in particular for tubes whose front face and surface of the mask are substantially planar.
• the support structure according to the invention makes it possible to increase its rigidity and to make the tube less sensitive to vibrations from its environment.
• FIG. 3 illustrates a first embodiment of the invention.
• the support 200 is made from a metal plate of substantially constant thickness, made from a single alloy or from a bimetal. It comprises a central part 201 forming a spring, a first end portion 202 folded relative to the central part and pierced with an opening 106 intended to engage around a pin included in the front face of the tube and a second end portion 203 folded so as to be able to bear against the surface of the frame.
• the central part 201 of the support 200 widens from the first end portion 202 towards the second end portion 203. In this way the second end portion 203 has a width along the direction of the longitudinal axis Z plus important than the first end portion 202.
• the second end portion 203 is welded at at least two points 204, 205 to the flange of the frame; these two weld points are arranged in a direction substantially parallel to the axis Z so as to form with the vertex represented by the opening 106 an acute angle ⁇ .
• this angle ⁇ should preferably be chosen to be greater than 10 ° to offer an increase in mechanical rigidity sufficient to improve the behavior of the tube in the face of external vibrations. Given the constraints of space and the size of the different parts constituting the tube, the best compromise in terms of mechanical rigidity of the supports 200 with respect to these constraints leads to choosing ⁇ between 10 e and 50 °.
• FIG. 4 illustrates a second embodiment of the invention.
• the support 210 according to this mode is produced from a metal plate of substantially constant thickness, made from a single alloy or from a bimetal. It comprises a first end portion 202 pierced with an opening 106 intended to engage around a pin included in the front face of the tube, a central portion 211 consisting of two arms 211a and 211b connected to the first portion d end, the folded ends 213a and 213b of the two arms constituting the second end portion 213 of said support 210.
• the two arms form an angle preferably chosen between 10 ° and 50 ° for the same reasons of compromise as for the first mode of production and the welds on the frame flange are carried out on said ends 213a and 213b.
• This embodiment has two advantages: - it reduces the amount of material used to implement the invention - the support structure with two arms more substantially attenuates the vibrations of the frame / mask assembly at the resonance frequency of this last, frequency usually between 60 Hz and 100hz.
• FIGS. 5a and 5b illustrate an alternative embodiment for which the support means comprise a first elastic member as described in the previous exemplary embodiments, said first member being
• FIG. 5a shows a partial view of the support means composed of a first elastic member 200 comprising two arms 211a and 211b, the ends of which are attached to a second member 300.
• This second member is produced using a metal plate whose ends 302 and 303 are folded relative to its central part 301 so that these ends can be attached respectively to the ends 213a and 213b of the arms of the first member and to the surface of the flange 21 of the frame.
• FIG. 5b shows the support means in place along a section plane AA 'parallel to the longitudinal axis Z and perpendicular to one of the arms of the first member 200.
• the second member makes it possible to attach the first elastic member 200 to the frame at a point in space where the frame itself is not physically located. Furthermore, this second member can contribute to the movements of the frame / mask assembly during the heating transients when the tube is lit, movements due to the expansion of the frame. At that moment.
• the control of these movements is carried out by choosing for example the thickness of the material constituting the second member; either this thickness is of the same order as the material of the first member and the expansion of the frame is then absorbed by the elasticity of the two members, or this thickness is greater making the second member rigid relative to the first and the expansion of the frame is then absorbed only by the first member.
• the above examples are not limitative.
• a cathode ray tube may comprise a single support in accordance with the invention in combination with other supports according to the state of the art.
• this support according to the invention will be attached to the middle of one of the sides of the frame in association with four supports according to the state of the art themselves arranged at the four corners of said frame.
• two supports according to the invention can be attached to two opposite sides of the frame.
• all of the supports for the frame can be made up of supports in accordance with the present invention.

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• Electrodes For Cathode-Ray Tubes (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (5)

Family Cites Families (11)

• 2004
  • 2004-02-23 IT IT000302A patent/ITMI20040302A1/it unknown
• 2005
  • 2005-01-31 EP EP05717698A patent/EP1719149A2/de not_active Withdrawn
  • 2005-01-31 US US10/589,816 patent/US20070164650A1/en not_active Abandoned
  • 2005-01-31 WO PCT/FR2005/050059 patent/WO2005086200A2/fr not_active Ceased
  • 2005-01-31 CN CNA200580005748XA patent/CN1922704A/zh active Pending

Non-Patent Citations (1)

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