JPH01206541A - Face plate of color cathode ray tube and method of forming color fluorescent material arrangement on it - Google Patents

Abstract

PURPOSE: To reduce pollution between a photosensitive resist layer and a face plate, by forming the photosensitive resist layer on an opaque layer, formed on the inside of the face plate of a color cathode-ray tube, and inserting the face plate into an unfittable vacuum tube including a shadow mask and an electron gun means for generating plural electron beams to make a resist an active condition. CONSTITUTION: A CRT face plate 1, a shadow mask 2 matching the face plate 1, and a shadow mask frame 3 is mounted on the shell 4 of an unfittable CRT system. A dual electron gun 8 is provided on the inner side of the neck part of the shell 4 to scan an electron beam by a scanning coil 9 provided on the outer side of a neck 7. When a phosphor screen is manufactured, the opaque coating 30 of the plate 1 is formed to form electronic photosensitive resists 31-34 on the coating 30. The respective resists 32-34 are exposed on the screen of the face plate 1 by scanning the electron beam to be turned into an active condition.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method of preparing a phosphor screen.

A color cathode ray tube (CRT) comprises a screen in which an array of different phosphors that emit light of different colors in response to an electron beam are precisely positioned on the screen of the CRT with respect to the holes (or slits) in the jade maze. ing. The electron gun arrangement produces a different electron beam for each color. Many methods of making phosphor arrays are known.

U.S. Patent No. 4,251,610 (Tektronix Inc.)
An exemplary method is disclosed in which an opaque layer is first formed on the interior surface of the screen.

Assuming that three different "colored" phosphors are used, three arrays of holes are created in the opaque layer. this is,
By coating an opaque layer with a photoresist and illuminating the coating through a shadow mask with light from a light source simulating three electron beams, developing the resist and using the developed resist as a mask. This is done by etching the layer and removing the resist.

A phosphor of one color, for example green, is placed in one of the arrays using the following process.

A coating of photoresist is placed over the entire opaque layer and holes. This coating is exposed to ultraviolet (UV) light from a light source simulating a green electron beam through a shadow mask. The coating is then developed to expose the "green" array of holes, leaving two other arrays covered by resist. A "green" phosphor and a photosensitive adhesive are placed on the screen. The phosphor and bonding material are exposed to ultraviolet light through a screen to fix the green phosphor in the green hole. Excess phosphor and binder are removed, and the photoresist is removed.

This process is repeated for other colors. Each iteration begins with a new coat of photoresist covering the previously deposited phosphor, thus protecting the previously deposited phosphor from cross-contamination.

While the light beam moves in a straight line, the electron beam follows a path controlled by magnetic and electrostatic fields. It is known to use the electron beam itself to precisely form an array of holes in an opaque layer. It refers in particular to, for example, the British patent application G published on 31 December 1986.
B 2 176 647A (Rank Electronic Tubes Limited)
r.

Ni'c Tubes Ltd)).

In one exemplary method disclosed in CB 2 176 647A, an opaque layer is first formed on the inner surface of a CRT screen.

An array of phosphors is placed using the following steps.

The layer is coated with an electron beam-sensitive resist that is exposed to, for example, a "green" electron beam through a shadow mask. The electron beam resist is developed and the layer is etched to create an array of "green" apertures or holes thereon.

A "green" phosphor plus a photosensitive binder is applied and exposed to UV light through a screen to fix the phosphor in the aperture. The electron beam resist is removed. A new coat of electron beam resist is then placed and the process repeated for that or each color of phosphor. Although this method is effective, there is some cross-contamination of phosphors that actually reduces color purity.

In another method proposed in GB 2 176 647A, three arrays of apertures are first created in an opaque layer using electron beam exposure of an electron beam sensitive resist to be removed.

Another e-beam resist is then placed, exposed and developed using, for example, a "green" e-beam, and a "green" phosphor and photosensitive binder are irradiated through a screen. is fixed in the "green" aperture by UV. The phosphors of that color or of each color are fixed in the array of apertures in a similar manner. As in Tektronix US Pat. No. 4,251,610, UV light illuminates all apertures in the opaque layer. In the Tektronix patent, a layer of photoresist blocks UV light in apertures other than those associated with the color of the phosphor on which it is placed because the layer of photoresist is thick. However, e-beam resists are usually not thick enough to completely block UV light. Therefore, the resist may be partially photosensitized on other holes, which may cause contamination of other holes upon development.

According to one aspect of the invention, it is desirable to provide a phosphor screen with precise placement of phosphors while reducing cross-contamination of phosphors.

In accordance with the above-mentioned aspects, there is provided a method of forming a plurality of different interspersed arrays of phosphors inside a faceplate of a color cathode ray tube, the method comprising: for each array a completed tube; A mask is formed by irradiating the electron-sensitive resist layer with an electron gun in a removable vacuum tube substantially co-located with respect to the array with an electron gun energizing the array in the mask; Fixed in place, the masks are formed in sequence, and each mask and phosphor array is coated with a layer of resist that is used to fabricate the next mask before the next mask and phosphor array is formed. , all resist layers are held until all phosphor arrays are formed.

According to another aspect of the invention, the difficulties associated with removing excess phosphor are at least reduced, while providing different phosphors of good color purity for the electron guns that energize them during operation of the screen. It would be desirable to provide a method of preparing a phosphor screen that is accurately positioned.

According to another aspect, a method is provided for forming a plurality of interspersed color phosphor arrays on the inside of a faceplate of a color cathode ray tube, which comprises: A) forming an opaque layer on the inside of the faceplate; B) providing a first layer of electron-sensitive resist on the opaque layer; C) a removable mask comprising a shadow mask and electron gun means for generating a plurality of electron beams; D) assembling a faceplate into a vacuum tube and pumping to a vacuum; irradiating said layer of resist through a shadow mask with a beam of at least one of the following: E) removing the faceplate from the vacuum tube; G) providing a phosphor and a photosensitive binder on the formed mask; (i) exposing the phosphor and photosensitive binder through the aperture to light such that the portion thereof that is located in alignment with the aperture in the mask is activated; J) further processing the faceplate to form a first said array of phosphors of a first color in registration with the aperture; K) providing a second layer of electron-sensitive resist over the first array; K) directing a second of said beams to form a second said array of phosphors of a second color; Step C)
repeating steps 1) to 1).

For a better understanding of the invention, and to show how the invention may be carried out, reference will now be made to the accompanying drawings by way of example.

FIG. 1 shows an actual CRT face plate 1 and its matching shadow mask 2 and shadow mask frame 3.
1 illustrates a "removable" CRT system that accurately simulates a completed CRT using a . These are installed in a jacket 4, which can be made of metal, glass or ceramic, and which is connected by a tube 5 to a vacuum pump system 6. A dual electron gun 8 is provided inside the neck of the jacket 4, and a CRT scanning coil 9 is provided outside the neck 7, so that the electron beam emitted by the electron gun 8 has an appropriate voltage waveform. It can be made to scan by application. To be clear,
Although only two electron beams are shown, any number of electron beams and their corresponding phosphor arrays may be used. In use, the entire assembly within the envelope 4 is vacuum tight and the faceplate 1 is connected to the envelope 4 by a gasket 10.

The process of manufacturing a phosphor screen will now be described with reference to FIGS. 2A-2M.

The CRT faceplate 1 is separated from the shadow mask 2 and provided with an opaque coating 30.

This coating may be reflective, for example aluminum, or it may be a black coating, such as black chrome, applied by vapor deposition in a gaseous atmosphere by well-known and well-established methods. obtain. A thin first layer of electron-sensitive resist 31 is then applied to the faceplate 1, for example by spinning. Next, the resist layer is hardened by baking. (The type of resist is "positive" or "positive" depending on whether it is softened or hardened, respectively, under the action of the m-beam.
For convenience, the method described here is a process for a "positive" resist).
. Various types of electron-sensitive resists may be used, such as those consisting of methyl methacrylic acid (metbyxm
ethacrylic acid) and methacryloyl chl
oride) and other methacrylates (methac
rylates), i.e. PM type resist. As an alternative, cellosolve acetate (cel
polymethylmethacrylate (losolve acetate)
Electro-sensitive resists of the PMMA type may be used, including PMMA-type electron-sensitive resists (Rylates).

A particular commercially available electron-sensitive resist that may be used is 15OFINE E-8 positive resist grade P7.

Next, the face plate 1 and the shadow mask 2 are assembled together to form a removable CRT as in FIG.
will be placed in A suitable voltage is applied and the resist 31 is further exposed to the second C from one electron gun in the electron gun housing 8, such as the gun responsible for the green content on the screen, through the shadow mask 2. It is exposed to a scanning electron beam from the direction indicated by the arrow in the figure. The portions of the resist 31 that receive the electron beam through the holes in the shadow mask are softened. Next, the faceplate assembly is a removable CRT
The resist layer 31 is then treated with a developer solution, in which case the properly exposed dots or lines are removed, leaving unexposed areas. This step is illustrated in Figure 2D, where the opaque layer 30 on the faceplate 1 is overlaid with an apertured layer of developed resist 31.

The exposed portions of opaque layer 30 are then etched away through apertures or holes in resist 31, allowing unexposed portions of opaque layer 30 to remain, as shown in FIG. 2E. , thus forming a mask having an aperture 32 therein. If the opaque layer 30 is black chrome, the etchant used is ferric ammonium nitrate.
perchloric acid and demineralized water. If aluminum forms the opaque layer 30, it may be etched using dilute caustic soda.

A first phosphor material emitting a first color, such as green, when bombarded with electrons forms a mixture 33 that is slurried or precipitated onto the faceplate layer. For example, polyvinyl alcohol (polyvinyl alcohol) is sensitized with ammonium bichromate.
lyvinylalcohol). This stage is shown in the m2F diagram. The faceplate 1 is exposed to UV from a light source shining through the glass faceplate 1 in the direction of the arrow shown in FIG. 2G, so that the photoresist and phosphor mixture 3 present in the apertures 32
Part 3 is polymerized. As a result of developing the resist, the second G
A dot or line 33' of cured phosphor remains in the aperture 32 as shown. The remaining electron-sensitive resist 31 is retained.

A second layer 34 of electron-sensitive resist is now applied by spinning as before, as shown in FIG. 2H. A second layer of resist 34 covers the first layer of resist, for example a green phosphor. Next, the face plate 1 is assembled together with the shadow mask 2,
placed on the removable CRT shown in FIG.
Furthermore, the first and second layers 34 of resist are exposed to a scanning electron beam through the shadow mask 2 from the direction indicated by the arrows in FIG.

In this case a different one of the electron guns is used to generate the beam, for example the gun responsible for the red content on the screen. A first layer 31 of resist and a second layer receiving an electron beam through holes in a shadow mask.
portions of layer 34 are now in a softened state, and as before, the faceplate assembly is then removed from the removable CRT and first resist layer 31 and second resist layer 34 are exposed to a developer solution. The exposed dots or lines 35 of the resists 31 and 34 are then removed, leaving unexposed areas.

The further exposed portions of the opaque layer 30 are then etched away through the apertures 35 in the resist layers 31 and 34, and the opaque layer 30 is then etched away, as shown in the figure.
0 unexposed areas are allowed to remain.

A second phosphor material emitting a second color, for example red, is dichromated so as to form a mixture which, when bombarded with electrons, is slurried onto the faceplate layer as before. bLchromated polyvinyla
mixed with a UV sensitive photoresist such as lcohol).

The faceplate is exposed to UV light from a diffuse source illuminated through the glass faceplate 1 so that the portions of the photoresist and phosphor mixture residing in the apertures 35 polymerize.

Developing the photoresist results in a dot or line 36 of hardened phosphor remaining in the aperture 35, as shown in FIG. 2L. The first and second layers of electron-sensitive resist are retained.

This process is repeated by applying a third layer of resist over the first and second layers and over the red and green phosphors. The third layer is exposed to a "blue" electron gun through a shadow mask and developed, the opaque layer is etched, and the "blue" phosphor is fixed in the aperture as described above. Ru. The results are shown in Figure 2M.

As shown in FIG. 2M, the arrays of red phosphor 33', green phosphor 36 and blue phosphor 37 are used to generate a red electron beam and a green electron beam, respectively. A blue electron beam is placed in a scattered relationship on the faceplate 1 in alignment with the point at which it irradiates the faceplate 1 .

The second iteration of this process can be omitted if it is necessary to make a screen with only two colors of phosphors. Similarly, creating screens with more than three colors may require additional iterations.

By holding the resist layer, each phosphor to be fixed in place is protected from cross-contamination by later phosphors.

Because sets of holes 32, 35, etc. are made one at a time, and the opaque layer thus acts as a mask, even when two or more layers of resist are present, they are usually too thin to be exposed to UV light. It is possible to use an electron-sensitive resist that cannot itself act as a mask.

Once all the required phosphors are fixed in place on the screen, the various resist layers 31, 34 etc. are removed and the phosphors and opaque layers are removed as shown in FIG. 2M. It is lacquered and aluminized (38) in a manner known in the art.

Although reference has been made to red, green, and blue fluores, other colored fluores may be used, such as yellow, magenta, and blue-green. .

[Brief explanation of the drawing]

FIG. 1 is a side view in longitudinal section of a "removable" cathode ray tube (CRT) for use in the present invention. 2A-2M are partial schematic diagrams in cross-section of a CRT faceplate illustrating different stages in the manufacture of a cathode ray tube screen. In the figure, 1 is a CRT face plate, 2 is a shadow mask, 3 is a shadow mask frame, 4 is an outer cover, and 8
is a multiple electron gun, 9 is a scanning coil, 10 is a gasket, 3
0 is an opaque layer, 31 and 34 are resist layers. Patent Applicant: Rank Brimer Limited Drawing 8
(No change in content) Procedural amendment calculation (method) % formula % 1. Indication of the case 1988 Patent Application No. 323162 2. Name of the invention Face plate of color cathode ray tube and formation of color phosphor array thereon Method 3: Relationship with the person making the amendment Patent applicant address: Middleton Greenside Way, Middleton Greenside Way, Manchester, M24, UK (no street address) Name: Rank Brimer Limited Representative: G.
Earl Bonyer 4, Agent Address: 6, Sumitomo Bank Minamimorimachi Building, 2-1-29 Minamimorimachi, Kita-ku, Osaka, 4. Column for the representative of the patent applicant, all drawings, power of attorney and translation 7, and contents of the amendment as shown in the attached sheet. Please note that there are no changes to the content of the drawings. that's all

Claims (9)

[Claims] (1) A) forming an opaque layer on the inside of the faceplate; B) providing a first layer of electron-sensitive resist on the opaque layer; and C) generating a shadow mask and multiple electron beams. D) assembling the faceplate into a removable vacuum tube containing electron gun means for causing the shadow mask to emit an aperture in the shadow mask and the resist at a location corresponding to one of the beams; irradiating the layer of resist with the single beam through a shadow mask so as to activate the layer of resist; E) removing the faceplate from the removable vacuum tube; F) in the position. G) treating the faceplate utilizing an activated electronic resist material to form a mask in the opaque layer having apertures; and G) disposing a phosphor and a photosensitive binder on the formed mask. H) exposing the phosphor and photosensitive binder through the aperture to light from the other side of the faceplate, a portion thereof being positioned in alignment with the aperture in the mask; I) further processing the faceplate to form a first array of phosphors of a first color in alignment with the aperture; and J) forming a second array of phosphors of a second color;
A method for forming a plurality of interspersed color phosphor arrays inside a faceplate of a color cathode ray tube, the method comprising repeating steps C) to I) above using a second of said beams. K) between the first stage I) and the second stage C),
a second layer of electron-sensitive resist over the first array of phosphors. (2) providing a third layer of electron-sensitive resist over the first and second layers of resist and over the first and second arrays of phosphors; 2. Further comprising repeating steps C) through I) utilizing a third of said beams to form a third said array of phosphors of a third color. The method described in. 3. The method of claim 1 or claim 2, further comprising the step of: (3) removing the layer of electron-sensitive resist after all arrays of phosphors have been formed on the faceplate. (4) The method according to any one of claims 1 to 3, wherein the opaque layer is a metal layer. (5) The method according to any one of claims 1 to 4, wherein the opaque layer is black. (6) A method of forming a plurality of different interspersed arrays of phosphors on the inside of a faceplate of a color cathode ray tube, the method comprising: forming a completed CR for each array;
A mask is formed by irradiating the electron-sensitive resist layer with an electron gun in a removable vacuum tube that is substantially co-located with respect to the array with an electron gun energizing the array at T, and the phosphor is in contact with said mask. the masks are formed in sequence, and each mask and phosphor array is covered with a layer of resist that is used to make the next mask before the next mask and phosphor array is formed. and all resist layers are retained until all phosphor arrays are formed. (7) forming an opaque layer on the faceplate, the mask being formed on the opaque layer using the resist layer, the mask being used to form a respective array of apertures in the opaque layer; 7. The method of claim 6, wherein the phosphor is mixed with a photosensitive binder and fixed in each array of holes by illuminating them with light through the faceplate. (8) A face plate manufactured by the method according to any one of claims 1 to 7. (9) A cathode ray tube comprising the face plate according to claim 8.