KR100322783B1 - Method of developing a latent charge image - Google Patents

Abstract

In the method for developing the electrostatic potential charge image formed on the photoreceptor 36 provided on the inner surface of the faceplate panel 12 of the CRT 10, the side wall 50 and the other end sealed by the bottom end 44 are provided. The developing device 40 having the developing chamber 42 having the panel support 46 is used. The opening 48 is formed through the panel support 46 to provide access and support to the faceplate panel 12. The panel grid 74 is provided adjacent to the inner surface of the faceplate panel 12 and operates at a first potential to control the electric field from the latent charge image. The tank grid 56 is provided in the developer 40 and is spaced apart from the side wall 50, the bottom surface 44 and the panel grid 74. A triboelectric gun 84 is provided in the developer 40 for delivering the desired charge polarity to the screen material and for distributing the charged screen material on a latent charge image. Voltmeter 66 and phosphorus application monitor 90 monitor the application of the charged screen component onto the latent charge image, and controller 68 controls the application of the charged screen component when sufficient material is applied. Terminate The tank grid 56 operates at a potential different from that on the panel grid 74 so that the tank grid 56 controls the electrostatic force in the developer 40.

Description

Latent charge image development method {METHOD OF DEVELOPING A LATENT CHARGE IMAGE}

E. An apparatus for developing latent charge images on a photoreceptor provided on an inner surface of a viewing faceplate of a display device such as a cathode-ray tube (CRT) using triboelectrically charged particles. H. yen. G. H. N. Riddle et al., US Pat. No. 5,477,285, issued December 19, 1995. In a first embodiment of the patent for the developing apparatus, a developing chamber having an insulating side wall and an insulating panel support is disclosed. A triboelectric gun is provided in the developing chamber for directing the charged screen component material onto the photoreceptor provided on the inner surface of the CRT faceplate panel. This developing chamber has the disadvantage of generating an electrical charge that builds up on the insulating sidewalls of the electrostatically charged screen component. The electrostatic force on this sidewall is not well controlled, and this electrostatic force changes as the charge changes. For example, when cleaning the developing chamber to remove excess screen structure materials from the sidewalls, the electrostatic charge is reduced. Electrostatic charges also change when moisture changes. The measured electrostatic field in the developing chamber operating has been reported to vary from 500 to 5000 volts. In another embodiment of the development chamber disclosed in US Pat. No. 5,477,285, referenced above, an interior chamber of conductive material comprising sidewalls and bottom surfaces is provided in the development chamber. The conductive inner chamber is electrically fluid and induces excess screen constituents out of the powder cloud created in the inner chamber by the friction stun gun, thereby accumulating space charge in the inner chamber and high electrostatic charge on the chamber wall. Prevent both potentials. However, screen components that accumulate in the form of 'snow banks', which are agglomerated particles on the conductive sidewalls of the inner chamber, may produce large agglomerated particles on the screen if the agglomerated particles are removed from the sidewall. Reported. Therefore, it is desirable to eliminate the disadvantages of the conventional developing apparatus discussed above.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of developing a latent charge image on a photoreceptor provided on an inner surface of a face plate of a water tube (CRT). A method of operating a tank grid to control it.

1 is a partial plan view along an axial direction of a color CRT manufactured according to the present invention;

2 is a partial view of a CRT faceplate panel having a matrix on its inner surface during one stage of the manufacturing process;

3 is a partial view of the completed screen assembly of the tube shown in FIG. 1, FIG.

4 is a partial view of a CRT faceplate panel showing a photoreceptor covering a matrix during another stage of the manufacturing process

5 is a front view of a developing apparatus used in the method of the present invention.

According to the present invention, a method of developing an electrostatic latent charge image formed on a photoreceptor provided on an inner surface of a faceplate panel of a CRT is disclosed. In the present invention, a developer tank having one end portion closed by a bottom surface portion and the other end portion closed by a panel support having openings through the panel support for providing access to the faceplate panel is used. . The panel grid is provided proximate to the inner surface of the faceplate panel and operates at a first potential to control the electrostatic field of the latent charge image. The tank grid is provided in the developer tank and is spaced apart from the side walls, the bottom surface and the panel grid. The trickle gun assembly is provided in a developer tank for delivering the desired charge polarity to the screen material and for distributing the charged screen material onto the latent charge image. According to the present invention, means are provided for monitoring the application of the charged screen component on a latent charge image and a means for terminating the application of the charged screen component. A novel aspect of the present invention is that the tank grid controls the electrostatic force in the developer tank by operating the tank grid at a potential different from that on the panel grid.

1 shows a color CRT 10 having a glass envelope 11 comprising a rectangular faceplate panel 12 connected by a rectangular funnel 15 and a tubular neck 14. Funnel 15 has an internal conductive coating (not shown) that contacts anode button 16 and extends to tubular neck 14. The panel 12 includes a viewing faceplate 17 and a vertical flange or sidewall 18, which are sealed to the funnel 15 by a glass fleet 19. As shown in FIG. 2, a relatively thin light absorbing matrix 20 having a plurality of openings 21 is provided on the inner surface of the viewing face plate 17. The fluorescent tricolor screen 22 reaches the inner surface of the faceplate 17 and covers the matrix 20. The screen 22 shown in FIG. 3 is preferably located in the center of one of the different ones of the matrix openings 21 and arranged in a circular order, in color groups or pixels or three sets of three strips. A line screen comprising multiple screen elements consisting of strips R, B, G, blue, and green-emitting. This strip extends generally in the normal direction to the plane of the electron beam being generated. In the viewing position of the normal in the present embodiment, the in strip extends in the vertical direction. Preferably, the phosphor strip portion covers at least a portion of the light absorbing matrix 20 surrounding the opening 21. In this regard, a dot screen may also be used. The thin conductive layer 24 (preferably aluminum) covers the screen 22 and provides a means for reflecting light emitted from the phosphorus element through the faceplate 17 as well as applying a uniform potential to the screen. to provide. Screen 22 and covering aluminum layer 24 comprise a screen assembly. Referring again to FIG. 1, a multi-opening color selection electrode 25, such as a shadow mask or a focus mask, is removably mounted to the screen assembly by conventional means at a predetermined spacing ratio. The color selection electrode 25 is detachably attached to a plurality of studs 26 embedded in the side wall 18 of the panel 12.

An electron gun (shown roughly in dashed lines) 27 generates three electron beams 28 and directs them along the converging path to the screen 22 through the opening of the color selection electrode 25 to the center of the neck 14. Mounted. The electron gun is conventional and may be any suitable gun known in the art.

Tube 10 is designed for use by an external magnetic deflection yoke, such as yoke 30 located at the junction of the funnel and neck. When initiating operation, yoke 30 controls the three beams 28 with a magnetic field to scan the beam horizontally and vertically on the screen 22 with a square raster. The first deflection plane (when deflection is zero) is shown by the P-P line at approximately the center of the yoke 30 in FIG. 1. For simplicity, in the deflection zone, the actual curvature of the deflection beam path is not shown.

Screen 22 was manufactured by an electrophotographic screening (EPS) process disclosed in US Pat. No. 4,921,767, issued May 1, 1990 to Datta et al. Initially, the panel 12 is washed by rinsing with a corrosive solution, as is known in the art, then rinsed with water, then etched with buffered hydrofluoric acid and again rinsed with water. The inner surface of the viewing faceplate 17 is then light, preferably using a conventional wet matrix process disclosed in US Pat. No. 3,558,310, issued Mayaud, January 26, 1971. Provided to the absorbent matrix 20. In this wet matrix process, a suitable photoresist solution is applied to the inner surface, for example by spin coating, and the photoresist solution is dried to form a photoresist layer. Thereafter, the color selection electrode 25 is inserted into the panel 12, and the panel is a three-in-one lighthouse that exposes the chemical radiation to the photoresist layer from a light source that projects light through the opening of the color selection electrode. -in-one lighthouse (not shown). The exposure is repeated two or more times by a light source positioned to mimic the path of the electron beam from the three electron guns. Light selectively changes the solubility of the exposed areas of the photoresist layer. After three exposures, the panel is removed from the lighthouse and the color selection electrode is removed from the panel. The photoresist layer is developed using water to remove the higher solubility region in the photoresist layer by exposing the basic inner surface of the viewing faceplate, leaving the exposed but lower solubility region in the photoresist layer. Thereafter, a suitable solution of the light absorbing material is uniformly provided on the inner surface of the faceplate panel so that the exposed portion of the viewing faceplate and the exposed but less soluble region of the photoresist layer are maintained. The layer of light absorbing material that has been dried and developed using a suitable solution dissolves the basic light absorbing material that forms the opening 21 in the retained portion of the photoresist layer and the matrix 20 attached to the inner surface of the viewing faceplate. Will be removed. For panel 12 having a diagonal diameter of 51 cm (20 inches), openings 21 formed in matrix 20 have a width of about 0.13 to 0.18 mm, and opaque matrix lines have a width of about 0.1 to 0.15 mm. Has The inner surface of the viewing faceplate 17 is then covered with a suitable layer of volatile organic conductive (OC) material (not shown) that provides an electrode (not shown) for the coated volatile organic photoconductive (OPC) layer. do. In bonding, the OC layer and the OPC layer include the photoreceptor 36 shown in FIG.

Suitable materials for the OC layer containing any tetrachloride polyelectrolyte are described by December 6, 1994. US Pat. No. 5,370,952 to P. Datta et al. Preferably, the OPC layer is made of polystyrene; Electron donor materials such as 1,4-di (2,4-methylphenyl) -1,4 diphenylbutatriene (2,4-DMPBT); Electron acceptor materials such as 2,4,7-trinitro-9-fluorenone (TNF) and 2-ethyllanthroquinone (2-EAQ); And a layer of OC with a solution containing a suitable solvent such as toluene, silane, or a mixture of toluene and silylene. Surfactants such as silicone U-7602 and plasticizers such as dioctyl phthalate (DOP) may also be added to the solution. Surfactant U-7602 is available from Union Carbide, Danbury, CT. Photoreceptor 36 was disclosed in US Pat. No. 5,519,217 issued to Wilbur et al. On May 21, 1996, but the photoreceptor 36 has a voltage in the range of approximately +200 to +700 volts. By using a corona discharge device (not shown) that charges, the charge is uniformly electrostatically charged. Thereafter, the color selection electrode 25 is inserted into the panel 12 located on the lighthouse (not shown), and the positively charged OPC layer of the photoreceptor 36 forms the color selection electrode 25. It is exposed to light from other light sources of sufficient intensity, such as xenon flash lamps or mercury arcs provided in the lighthouse. The light passing through the opening in the color selection electrode 25 at the same angle as one of the beams of electrons from the electron gun of the tube discharges the illuminated area on the photoreceptor 36 and causes a latent charge image (not shown). ). The color selection electrode 25 is removed from the panel 12, and the panel is located on the first phosphor developer 40 as shown in FIG.

The developer 40 includes a developing chamber 42 having a bottom end 44 and an upper end or panel support 46. The panel support 46 is preferably formed of an insulating material and includes an opening 48 with dimensions slightly larger than the CRT faceplate panel 12. The panel 12 is supported on the panel support 46. The developing chamber 42 further includes an outer side wall 50 extending between the bottom end 44 and the panel support 46. The conductive inner side wall 52 is spaced apart from the outer side wall 50 and extends from the conductive inner bottom end 54 to the plane A-A adjacent the panel support 46. The conductive inner side wall 52 and the bottom end 54 are connected to the high voltage source 55 and biased at a potential of at least 2V, but preferably to a positively charged cloud of phosphorus particles in the chamber 42. It forms a tank grid 56 that is in the range of 3 to 15 kV to provide repulsion and provides control of the clouds. The spacing 57 (between the outer and inner sidewalls 50 and 52) located around the top of the chamber 42 removes excess phosphorus particles that are not applied on the latent charge image formed on the photoreceptor 36. To provide. The exhaust port 58 is connected to a pump (not shown) which removes excess phosphorus from the developer 40.

Electrical contacts 60, such as stud contact springs, are provided to connect to one of the studs 26 embedded in the sidewall 18 of the faceplate panel 12. The conductive sheath of the photoreceptor 36 is electrically connected to the stud 26 by a contact patch (not shown). The contact patch disclosed in US Pat. No. 5,156,770 was issued to Wetzel et al. On October 20, 1990. The electrical contact 60 is connected to and grounded to a capacitor 64 that develops a voltage proportional to the charge of the triboelectrically charged phosphorus particles applied to the latent charge image on the photoreceptor 36. The voltage developed on capacitor 64 is monitored by voltmeter 66 and connected to a controller 68 that is programmed to terminate phosphorus application when the generated voltage reaches a predetermined value corresponding to the thickness of phosphorus required. It is. In each conventional power generation cycle, the voltage on capacitor 64 is grounded and discharged through contact 70 by the operation of controller 68. The high voltage source 72 is connected to the panel grid 74 to remove the electric field near the latent charge image formed on the photoreceptor 36. The structure and function of the panel grid 74 is disclosed in US Pat. No. 5,093,217, issued March 3, 1992 to Datta et al. Grid 74 is positively biased at about 2-3 kV and has the same polarity as the triboelectrically charged phosphor particles applied on the latent charge image.

Separate developer 40 is required for each of the three color emitters to prevent cross contamination, while a single developer is used and the color emitter material described above is fed into a common chamber, heterogeneous mixing. Pollution occurs. The external device for the development chamber 42 is a phosphorus reservoir 76 which includes a supply of dried powdered phosphorus particles.

During the development operation, phosphor particles are transported from reservoir 76 to venturi chamber 78 where phosphor particles are mixed by the appropriate amount of air. Actuation by air supply is achieved by opening the valve 80 controlled by the controller 68. The air pressure is set by the pressure regulator 82. Phosphorus particles are transported into the chamber 42 through the triboelectric gun 84, which is positively triboelectrically charged and directed towards the latent charge image on the photoreceptor 36. The positively charged first colored emission particles are repelled by the positively charged region on photoreceptor 36 and positively charged by a process known as technology such as 'reverse' phenomenon. It is applied on the area covered with. In the reverse phenomenon, triboelectrically charged particles in the screen construction material are repelled by similarly charged regions of the photoreceptor 36 and applied onto the discharged regions of the photoreceptor. The in-line of the first color emitting phosphorus is applied in a selected one of the openings 21 in the matrix 20, making the width and height from the center of the opening 21 to the edge of the surrounding matrix. When the application is complete, as shown in Fig. 3, each opening is completely larger than the size of the opening 21 in the light absorption matrix 20 so as to completely fill each opening and slightly cover the light absorption matrix around the opening. In line is required.

Referring to FIG. 5, a phosphor deposition monitor (PDM) device 90 is a pair of side rails 92 and 93 mounted to the support surface 46 of the developer 40 adjacent to the opening 48. And a support assembly having a). The side rails 92 and 93 are sufficiently spaced to permit the faceplate panel 12 located on the support surface 46 without interference from the side rails. A first pair of crossrails (only one pair is shown) is slidably attached to the side rails 92 and 93 and supports the first image device 96 that is slidably attached to the crossrail 94. The second image device 99 is also attached to the crossrail 94 in a sliding manner. Imaging devices 96 and 99 are mounted on 15 cm (6 inches) of viewing faceplate 17. Each imaging device 96 and 99 is movable in the x-y plane and can be tilted substantially parallel to the curvature of the viewing faceplate 17. Imaging devices 96 and 99 may be located anywhere on viewing faceplate 17 and provide a means for visually monitoring the application of the in-screen construction material. PDM apparatus 90 is disclosed in co-pending US patent application 728,010, filed Oct. 9, 1996 by Robert Junior Jr., et al.

In this process, the potential applied to the charged phosphorus cloud is controlled by the potentials on tank grid 56 and panel grid 74. The tank grid can be adjusted within the range of 3-15 kV by optimizing the uniformity of the flux of phosphorus in the developing process and powder cloud to control the electrostatic force in the developing chamber 42.

Another advantage of the tank grid 56 is that the tank grid eliminates phosphorus accumulated from the panel grid by 'reverse' biasing the two grids with negative voltage (i.e., biasing the grids 56 and 74). As such, phosphor particles may be withdrawn from panel grid 74 into developer tank 40 where phosphor particles may be removed through discharge port 58.

Although disclosed with respect to embodiments of phosphorus developers, the present invention also relates to EPS coated phosphorus to improve the cohesion of phosphorus to the basic photoreceptor and to planarize a film such as a layer comprising a photoconductor applied onto the matrix layer. It may also be used in electrostatic spray applications of aerosols, such as fixed materials sprayed onto the screen.

Claims (4)

One side is closed by the bottom 44 and the other end is closed by the panel support 46 having an opening 48 through the panel support to provide access to the faceplate panel 12. A developing chamber 42 having a; A panel grid (74) adjacent the inner surface of the faceplate panel (12); A tank grid (56) provided in said developing chamber (42) and spaced apart from said side wall (50), said bottom surface (44) and said panel grid (74); A triboelectric gun (84) for delivering a desired charge polarity for the screen construction material and for distributing the screen construction material onto the latent charge image; Means (66, 90) for monitoring the application of the charged screen component material onto the latent charge image; Photoreceptor 36 provided on the inner surface of the faceplate panel 12 of the CRT 10 using a developing device 40 comprising means 68 for terminating the application of the charged screen constituent material. A method of developing an electrostatic latent charge image formed on a screen component material that is suitably triboelectrically charged and dried powder form, Operating the panel grid 74 at a first potential to control an electric field from the latent charge image; Operating the tank grid (56) at a second potential different from the first potential to control the electrostatic force in the developer tank. The developing method according to claim 1, wherein the second potential is higher than the first potential. The method of claim 2, wherein the first potential is about 2 kV. The method of claim 2, wherein the second potential is in the range of about 3 to 15 kV.