Source: http://www.google.com/patents/US7416462?dq=6948823
Timestamp: 2015-11-27 06:49:37
Document Index: 30862393

Matched Legal Cases: ['Application No. 61', 'Application No. 9', 'Application No. 05', 'Application No. 7', 'Application No. 9', 'Application No. 7', 'Application No. 64', 'Application No. 3', 'Application No. 7', 'Application No. 8']

Patent US7416462 - Glass substrate processing method and material removal process using x-ray ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsTo reuse glass used in a flat panel display, processing suitable for global environment such as processing of separating a lead component must be realized. A disassembly processing method for a flat panel display having a structure in which a face plate and rear plate mainly containing glass are airtightly...http://www.google.com/patents/US7416462?utm_source=gb-gplus-sharePatent US7416462 - Glass substrate processing method and material removal process using x-ray fluorescenceAdvanced Patent SearchPublication numberUS7416462 B2Publication typeGrantApplication numberUS 11/025,991Publication dateAug 26, 2008Filing dateJan 3, 2005Priority dateSep 9, 1998Fee statusPaidAlso published asEP1119014A1, EP1119014A4, EP1119014B1, US6632113, US6951494, US20040002276, US20050159068, WO2000014763A1, WO2000014763A8Publication number025991, 11025991, US 7416462 B2, US 7416462B2, US-B2-7416462, US7416462 B2, US7416462B2InventorsTakashi Noma, Toyoko Kobayashi, Taiko Motoi, Hiromitsu Takase, Naoko Miura, Shin KobayashiOriginal AssigneeCanon Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManPatent Citations (57), Non-Patent Citations (2), Referenced by (10), Classifications (26), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetGlass substrate processing method and material removal process using x-ray fluorescence
US 7416462 B2Abstract
To reuse glass used in a flat panel display, processing suitable for global environment such as processing of separating a lead component must be realized. A disassembly processing method for a flat panel display having a structure in which a face plate and rear plate mainly containing glass are airtightly joined via a frame with frit glass is characterized by including the step of separating the face plate and rear plate joined with the frit glass. The separation step is characterized by separating the face plate and rear plate by cutting, dissolution, or melting.
1. A glass substrate processing method of detecting a surface state of a glass substrate and processing a substrate surface in accordance with a detection result, comprising:
the detection step of irradiating the glass substrate surface with a primary X-ray, and detecting a generated fluorescent X-ray to detect an element present on the glass substrate surface; and
the removal step of removing an element other than a glass constituent element from the glass substrate surface in accordance with a detection result of the detection step.
2. A glass substrate processing method according to claim 1, characterized in that the detection step of detecting an element present on the glass substrate surface comprises changing relative positions of the glass substrate and a fluorescent X-ray detector in accordance with a size of the glass substrate.
3. A glass substrate processing method according to claim 1, characterized in that a fluorescent X-ray detector irradiates with the primary X-ray a region wider than a region in which a fluorescent X-ray can be detected.
4. A glass substrate processing method according to claim 1, characterized in that an incident angle when the primary X-ray is incident on the glass substrate is not more than a critical angle of the primary X-ray.
5. A glass substrate processing method according to claim 1, characterized in that the removal step for the glass substrate surface is performed by polishing the glass substrate surface.
6. A glass substrate processing method according to any one of claims 1 to 5, characterized in that the detection step and the removal step for the glass substrate surface are repetitively performed.
7. A glass substrate recycling processing method in a flat display including a rear plate having a plurality of electron-emitting elements formed on a glass substrate, a face plate having an image display portion formed on a glass substrate, and a support frame which joins the plates so as to face each other, wherein
the processing method defined in any one of claims 1 to 5 is applied to a substrate surface of the rear plate or the face plate after the rear plate and the face plate are separated and extracted.
8. A glass substrate recycling processing method in a flat display according to claim 7, characterized in that a wiring line mainly containing Ag is formed on the glass substrate of the rear plate.
9. A glass substrate recycling processing method in a flat display according to claim 7, characterized in that a thin film containing an element other than a glass constituent element is formed on the glass substrate surface constituting the rear plate.
10. A glass substrate recycling processing method according to claim 7, characterized in that fit glass for joining the rear plate, the face plate, and the frame is dissolved to separate the rear plate, the face plate, and the frame. Description
This application is a continuation of International Application No. PCT/JP99/04866, filed Sep. 8, 1999, which claims the benefit of Japanese Patent Application as follows.
1) 10-255171 filed on Sep. 9, 1998
2) 10-263033 filed on Sep. 17, 1998
3) 10-263034 filed on Sep. 17, 1998
4) 10-268151 filed on Sep. 22, 1998
5) 11-004575 filed on Jan. 11, 1999
6) 11-032142 filed on Feb. 10, 1999
7) 11-032143 filed on Feb. 10, 1999
8) 11-033855 filed on Feb. 12, 1999
9) 11-045372 filed on Feb. 23, 1999
10) 11-047086 filed on Feb. 24, 1999
11) 11-047087 filed on Feb. 24, 1999
12) 11-047088 filed on Feb. 24, 1999
13) 11-047166 filed on Feb. 24, 1999
14) 11-248061 filed on Sep. 1, 1999
This is a divisional of application Ser. No. 10/462,740, filed on Jun. 17, 2003, now U.S. Pat. No. 6,951,494, issued on Oct. 4, 2005 which is a divisional of application Ser. No. 09/722,543, filed on Nov. 28, 2000, now U.S. Pat. No. 6,632,113, issued on Oct. 14, 2003.
The present invention relates to, in order to protect the global environment, a method of disassembling for scraping a flat panel display constituted by airtightly joining via a frame with frit glass or the like two substrates, i.e., a face plate (front glass substrate) and rear plate (rear glass substrate) mainly containing glass, a method of reusing a flat panel display, separating and recovering lead as a hazardous metal element among metal elements used for the flat panel display, and effectively reusing other noble metal elements and rare-earth elements, a method of dismantling an image forming apparatus welded with frit glass and recycling its face plate and rear plate, a method of recovering and reusing a spacer, a method of recovering fluorescent substances from a flat display apparatus or CRT (Cathode Ray Tube) for emitting light by irradiating a fluorescent substance-coated portion with an electron beam or ultraviolet ray, a display apparatus manufacturing method, an image display apparatus suitable for dismantling, disassembly, and reuse, a residual hazardous metal amount inspection apparatus for inspecting a hazardous metal amount contained in a waste or the like, and a fluorescent substance recovery method and apparatus in a flat display panel.
Conventionally, most of scrapped home appliances are shredded, valuables such as metals are recovered, and the remainders are disposed of as industrial wastes to a “least controlled landfill site” where the wastes are merely buried in a dug hole.
In recent years, a shortage of the capacity of disposal sites poses a serious problem, and environmental pollution by hazardous substances also poses a serious problem. For example, the cathode ray tube of a television uses a large amount of lead-containing glass. According to trial calculation by the Environment Agency, lead contained in scrapped cathode ray tubes amounts to 20,000 t every year, and most of lead is buried in least controlled landfill sites. However, rainwater naturally permeates in least controlled landfill sites, and these sites are not equipped with any drainage facility. It is being recognized that lead as a hazardous substance may diffuse.
Under these circumstances, conventional processing methods must be reconsidered. As for the cathode ray tube of a television, studies of shredding cathode ray tube glass into cullets (small glass pieces) and reusing them for cathode ray tubes have been made by Association for Electric Home Appliances. Of these studies, a system of extracting a cathode ray tube from a television main body and shredding the cathode ray tube into glass cullets has been developed (see, e.g., “Electrotechnology”, January, 1997).
A method of recovering glass as cullets is disclosed in, e.g., Japanese Laid-Open Patent Application No. 61-50688. There is also known a method of shredding cathode ray tube glass into cullets (small glass pieces) and reusing them for cathode ray tubes (e.g., Japanese Laid-Open Patent Application No. 9-193762). A method of separating a cathode ray tube into a face plate and funnel in accordance with materials, and shredding them into cullets is disclosed in, e.g., Japanese Laid-Open Patent Application No. 05-185064. Further, a method of separating a cathode ray tube into a face plate and funnel, peeling fluorescent substances and a black mask from the face plate, and recycling the face place is disclosed in Japanese Laid-Open Patent Application No. 7-037509.
To reuse cathode ray tube glass, the glass must be separated into panel glass and lead-containing funnel glass. This is because, if lead is mixed in panel glass by a predetermined amount or more, a browning phenomenon occurs, and the lead-containing glass cannot be reused as a raw material of the panel glass. For this reason, a cathode ray tube is separated into a panel and funnel. For this purpose, there are proposed a method of defining a position to cut a cathode ray tube (Japanese Laid-Open Patent Application No. 9-115449), and a method of melting frit glass which joins a panel and funnel, thereby separating the panel and funnel (Japanese Laid-Open Patent Application No. 7-45198).
As a technique of separating a funnel and panel welded with frit glass, a technique of separating a funnel and panel using thermal distortion in heat treatment is known as disclosed in, e.g., Japanese Laid-Open Patent Application Nos. 5-151898, 7-029496, 9-200654, and 9-200657.
In recent years, studies for applying cold cathode elements have enthusiastically been done. Known examples of the cold cathode elements are surface-conduction type electron-emitting elements, field emission type electron-emitting elements, metal/insulator/metal type electron-emitting elements. Compared to a thermionic cathode element, the cold cathode element can emit electrons at a low temperature. The cold cathode element does not require any heater, is simpler in structure than the thermionic cathode element, and can form a small element. Even if many elements are arranged on a substrate at a high density, problems such as thermal melting of the substrate hardly arise. In addition, the response speed of the thermionic cathode element is low because it operates upon heating by a heater, whereas the response speed of the cold cathode element is high.
Of cold cathode elements, surface-conduction type electron-emitting elements have a simple structure, can be easily manufactured, and allow forming many elements in a wide area. As disclosed in Japanese Laid-Open Patent Application No. 64-31332 filed by the present applicant, a method of arranging and driving many elements has been studied.
As applications of surface-conduction type electron-emitting elements, e.g., image forming apparatuses such as an image display apparatus and image recording apparatus, charge beam sources, and the like have been studied.
Particularly as applications to image display apparatuses, as disclosed in U.S. Pat. No. 5,066,883 and Japanese Laid-Open Patent Application Nos. 2-257551 and 4-28137, an image display apparatus using a combination of a surface-conduction type electron-emitting element and a fluorescent substance which is irradiated with an electron beam to emit light has been studied. The image display apparatus using a combination of a surface-conduction type electron-emitting element and fluorescent substance is expected to exhibit more excellent characteristics than other conventional types of image display apparatuses. For example, this image display apparatus is superior to a recent popular liquid crystal display apparatus in that the image display apparatus does not require any backlight because of self-emission type and that the view angle is wide.
A method of driving many field emission type electron-emitting elements arranged side by side is disclosed in, e.g., U.S. Pat. No. 4,904,895. A known application of FE type electron-emitting elements to an image display apparatus is a flat display reported by R. Meyer et al. [R. Meyer: Recent Development on Micro-tips Display at LETI”, Tech. Digest of 4th Int. Vacuum Micro-electronics Conf., Nagahama, pp. 6-9 (1991)].
An application of many metal/insulator/metal type electron-emitting elements arranged side by side to an image display apparatus is disclosed in Japanese Laid-Open Patent Application No. 3-55738.
Of these image forming apparatuses using electron-emitting elements, a thin flat display is space-saving and lightweight, and receives a great deal of attention as a substitute for a cathode ray tube type image display apparatus.
The interior of the airtight container in the image forming apparatus is kept at a vacuum of about 10−6 Torr. As the display area of the image display apparatus increases, the airtight container requires a means for preventing a rear plate and face plate from being deformed or destructed by the difference between internal and external pressures of the airtight container. If the rear plate and face plate are made thick, this increases the weight of the image display apparatus, and generates distortion and disparity of an image when viewed diagonally. Thus, the airtight container generally employs spacers each of which is made of a relatively thin glass plate whose surface is covered with an antistatic conductive film.
Flat displays including a vacuum fluorescent display (VFD), plasma display (PDP), and surface-conduction type electron source display (SED) in addition to the field-emission type electron source display (FED) and MIM type display described above are space-saving and lightweight, and receive a great deal of attention as substitutes for cathode ray tube type display apparatuses. Many flat displays have been studied and developed.
For example, the present applicant offers several proposals for an electron source constituted by arraying on a substrate many surface-conduction type electron-emitting elements as one type of cold cathode type electron-emitting elements, and an image display apparatus using this electron source.
The structure of the surface-conduction type electron-emitting element, the structure of the image display apparatus using this, and the like are disclosed in detail in, e.g., Japanese Laid-Open Patent Application No. 7-235255, and will be described briefly.
FIGS. 68A and 68B show a structure of a surface-conduction type electron-emitting element. Reference numeral 411 denotes a substrate; 412 and 413, a pair of element electrodes; and 414, a conductive film which partially has an electron-emitting portion 415. The substrate 411, element electrodes 412 and 413, conductive film 414, and electron-emitting portion 415 constitute an electron-emitting element 416.
As a method of forming the electron-emitting portion 415, a voltage is applied between the pair of element electrodes 412 and 413 to deform, change of properties, or destruct part of the conductive film, thereby increasing the resistance. This is called “electrification forming processing”. To form an electron-emitting portion having good electron emission characteristics by this method, the conductive film is preferably made of fine conductive particles. An example of the material is fine PdO particles. The voltage applied in electrification forming processing is preferably a pulse voltage. This processing can adopt either one of a method of applying pulses having a predetermined peak value, as shown in FIG. 69A, and a method of applying pulses whose peak value gradually increases, as shown in FIG. 69B.
To form a fine conductive particle film, fine conductive particles may be directly deposited by gas deposition. Instead, a method of applying the solution of a compound (e.g., organic metal compound) containing the constituent element of the conductive film and annealing the coating into a desired conductive film is desirable because no vacuum device is required, the manufacturing cost is low, and a large electron source can be formed. As a method of applying the organic metal compound solution, a method of applying the solution to only a necessary portion using an ink-jet apparatus is desirable because the method does not require any extra step for patterning of the conductive film.
After the electron-emitting portion is formed, a pulse voltage is applied between the element electrodes in a proper atmosphere containing an organic substance (this will be called “activation processing”). Then, a deposition film mainly containing carbon is formed at the electron-emitting portion and its vicinity to increase a current flowing through the element and improve electron emission characteristics.
After that, a step called “stabilization processing” is preferably performed. In this processing, while a vacuum container and electron-emitting element are heated, the vacuum container is kept evacuated to sufficiently remove an organic substance and the like, thereby stabilizing the characteristics of the electron-emitting element.
A method of forming the conductive film of an electron source using a surface-conduction type electron-emitting element by an ink-jet apparatus is disclosed in, e.g., Japanese Laid-Open Patent Application No. 8-273529.
The ink-jet apparatus will be explained briefly. Methods of discharging ink from the ink-jet apparatus are roughly classified into two types. According to the first method, a liquid is discharged as droplets using the contraction pressure of a piezoelectric element disposed at a nozzle. This method is called a piezo-jet method. In this method, a conductive thin film material is stored in an ink reservoir, and a predetermined voltage is applied to an electrical signal input terminal to contract the cylindrical piezoelectric element, thereby discharging a liquid as droplets.
According to the second method, a liquid is heated and bubbled by a heating resistor to discharge droplets. This method is called a bubble-jet method. In a bubble-jet type ink-jet apparatus, the heating resistor generates heat to bubble a liquid, thereby discharging droplets from a nozzle.
By using this ink-jet apparatus, an organic metal compound solution is applied as droplets to only a predetermined position. After the solution is dried, the organic metal compound is thermally decomposed by heating processing to form a conductive film from small particles of a metal or metal oxide.
FIG. 1 shows a structure of an image display apparatus. In FIG. 1, reference numeral 1 denotes a rear plate; 2, a face plate having a fluorescent film 2 b, metal back 2 c, and the like formed on the inner surface of a substrate 2 a; and 3, a support frame. The rear plate 1, support frame 3, and face plate 2 are joined and tightly sealed with frit glass to constitute an image display apparatus 15.
Flat panel displays having this structure are expected to abruptly increase in size and production. In these flat panel displays, frit glass used for sealing contains lead. The fluorescent substance 2 b serving as an image forming member, a spacer 4, and the like are high-cost members. Similar to cathode ray tube glass, establishment of a recovery system becomes an important subject in terms of “non-hazardous processing”, “volume reduction”, and “recycling”.
Problems to be solved by the present invention will be described in the following order, and examples for respective solving means and embodiments will be explained in this order.
[Problem 1] The FPD has a different structure from that of a cathode ray tube, and requires another processing method. That is, the FPD is constituted by airtightly joining two substrates, i.e., a face plate and rear plate mainly containing glass via a frame with frit glass. In general, frit glass containing a large amount of lead component so as to enable low-temperature baking is used.
For the same reason as a cathode ray tube, the FPD must be separated into glass not containing any lead and glass containing lead in order to reuse glass. In reusing members other than glass, lead must be removed.
The present invention has been made to solve the above problem, and has as its object to provide a processing method of easily reusing a scrapped FPD.
[Problem 2] It is another object of the present invention to provide a disassembly processing method including a separation/recovery method for lead as a hazardous metal, and a recovery/reuse method for rare elements such as noble metal elements and rare-earth elements.
[Problem 3] When a flat display is scrapped owing to generation of defects during the manufacture or upon the lapse of a service life, the entire display is shredded and scrapped, which increases the scrap amount. Recently, social demands arise for minimizing generation of wastes along with industrial activities, and reuse of members is becoming an imminent subject.
When a constituent material contains a hazardous element or the like, the hazardous element must be separated. A rear plate having electron-emitting elements that determines the performance of an image display apparatus often uses a high-cost substrate in order to obtain uniform element characteristics. Particularly, an element electrode which is first formed on a rear plate substrate is often made of a strong material which can resist subsequent steps.
The present invention has been made to solve this problem, and has as its object to provide a disassembly method of easily reusing a rear plate as an important constituent component of a scrapped image display apparatus, to provide a separation/recovery method for an element such as lead contained in a constituent material, and to efficiently form conductive films including the electron-emitting portions of a plurality of electron-emitting elements to be formed.
[Problem 4] When a flat display is scrapped owing to generation of defects during the manufacture or upon the lapse of a service life, the entire display is shredded and scrapped, which is economically undesirable because the constituent material contains a relatively high-cost material. Especially, the panel uses many spacers, and the manufacture of spacers requires a high manufacturing cost and long time because glass must be formed into thin pieces and conductive films must be formed. Even when a display is scrapped due to any reason, the cause is rarely a defective spacer, and spacers can often be reused without any problem.
For this reason, in scraping a flat display, spacers are desirably separated from other members, recovered, and reused.
As described above, the spacer is a thin plate and formed from a glass substrate, and may be damaged while a display is dismantled. Thus, development of a method capable of recovering spacers without any damage is desired.
[Problem 5] Conventionally, rare-earth elements have hardly been recovered from a display apparatus scrapped after use.
This is because (1) the amount of rare-earth elements used per display apparatus is very small, and the recovery is difficult, (2) rare-earth elements are used not as single substances but as compounds or alloys, and the separation cost is high, and (3) relatively low-cost imported rare-earth elements can be acquired at lower cost under the influence of the strong yen.
However, the recycling of these materials is desirably promoted in terms of environmental conservation and stably supply of rare-earth element resources. A method of recovering rare-earth elements from industrial products is an important subject. Note that rare-earth elements are mainly contained in fluorescent substances.
Fluorescent substances also contain chromium and sulfur elements, and these elements are also desirably recovered in terms of environmental conservation.
On the other hand, a face plate from which fluorescent substances are recovered loses almost all the smoothness of the inner surface. For this reason, such a face plate is conventionally shredded into cullets, buried in a least controlled landfill site, or reused as a glass material. In recent years, there are proposed a method of renewing the smoothness of the inner surface again by acid treatment and reusing the face plate, instead of shredding the face plate into cullets. However, this method is no longer effective because least controlled landfill sites are being saturated. Moreover, acid treatment is wet treatment, and is not preferable in terms of the cost and work environment.
The present invention has been made in consideration of the above situation, and has as its object to provide a method of efficiently recovering fluorescent substances contained in a display apparatus, and recovering and reusing a face plate while maintaining or renewing the smoothness of the inner surface.
[Problem 6] To dismantle, disassemble, and reuse an image display apparatus having an airtight container kept at a pressure lower than the atmospheric pressure, the interior of the airtight container must be returned to the atmospheric pressure. In returning to the atmospheric pressure, as the pressure difference from the internal pressure of the airtight container is larger, a larger amount of gas such as air often abruptly flows into the airtight container to damage the interior of the airtight container or destruct the airtight container. This may unexpectedly destruct the airtight container to scatter fragments, which is not preferable in terms of safety. This does not pose a serious problem when a CRT is shredded into cullets and reused as a glass material. However, to maximally reuse each member of an image display apparatus, the destruction not only increases wastes such as garbage in terms of resource conservation, but also wastes energy and labor. Particularly in an FPD, the container incorporates many atmospheric pressure-resistant constituent members such as spacers. The destruction greatly damages the atmospheric pressure-resistant constituent members, and the destructed members damage and destruct the interior of the airtight container of the image display apparatus to inhibit reuse of these members. A spacer requires a higher cost than other members because the shape of the side surface is made uniform or the spacer is uniformly coated with a film having a conductivity corresponding to the specifications of an image display apparatus in order to prevent distortion of an image.
The present invention has been made to solve the above problem, and has as its object to reuse a member in dismantling and disassembly by smoothly returning the interior of an evacuated airtight container of an image display apparatus to an external pressure.
[Problem 7] When a flat display is scrapped owing to generation of defects during the manufacture or upon the lapse of a service life, the entire display is shredded and scrapped, which poses an environmental problem, and is not economically preferable because the constituent material of an element includes a relatively high-cost material. For example, a panel uses many spacers. The spacers require a high manufacturing cost and long time because glass must be shredded into thin pieces and conductive films must be formed. Further, a rear plate, face plate, and support frame can be reused after portions which need to be repaired in accordance with the situation are appropriately processed.
For this reason, demands arise for recovering and reusing members without any damage and efficiently recovering resources in disassembling a flat display due to generation of defects during the manufacture or upon the lapse of a service life.
It is still another object of the present invention to provide a method of safely, easily dismantling a flat display into constituent members, and a flat display panel suitable for this disassembly.
[Problem 8] In disassembling and fractionating a cathode ray tube, flat panel display, and the like, the hazar