JPH05501584A - Electroluminescent phosphor with long service life and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Field of invention: electroluminescent phosphors with long service life and methods for their production The present invention relates to an electroluminescent phosphor (or phosphor material) and a method of manufacturing the same. especially, This invention provides a long-life phosphor, preferably an initially fired crystalline zinc sulfide phosphor. Based on zinc sulfide obtained by specially controlled mechanical deformation of precursors Regarding phosphors. The phosphors of the invention emit light over a broad spectrum of colors. However, the present invention is capable of controlling the blue and blue-green spectrum. It is particularly suitable for producing phosphor corpus luteum that emits in green and yellow parts.

This invention also relates to electroluminescent lamps and such This invention relates to a method of manufacturing a lamp. In particular, the present invention provides unexpectedly long life and long-lasting brightness. It relates to an electroluminescent lamp with a certain degree of brightness.

Background of the invention Electroluminescent (EL) phosphors, particularly zinc sulfide phosphors, and their preparation are well known. be. Such phosphors can be controlled to emit light over a broad spectrum. In particular, common phosphors emit light in the green and blue parts of the spectrum. shoot

Blue EL phosphors are known to have short lifetimes. Halving of many blue EL phosphors period (the time when the phosphor's brightness is half of its initial brightness), the phosphor is at 115 volts, Range of approximately 100 hours to approximately 300 hours when excited at 400 Hz (Hertz) It is surrounded by These phosphors can be used at higher voltages and frequencies. In other cases, the half-life is even shorter.

Green EL phosphors have a longer half-life than blue EL phosphors, typically 115 ports. , about 10-1000 hours at 400Hz, but at higher voltages and/or At higher frequencies, the half-life is much shorter. The above data is typical for blue phosphors. emit light in the 15ft-L range; green EL phosphors typically emit light in the 25ft-L range. It is based on a typical EL clamp construction type that emits ambient light.

Blue EL phosphors typically contain zinc sulfide, a copper activator, and one or more halogens. Prepared by calcination of halide flux at high temperature be done. ZnS:Cu:X containing about 0.05% by weight or more of Cu (X=C1 or Br) phosphors are typically blue-green rather than blue. Contains Cu (copper) It is known that as the amount increases, the luminescence gradually softens from blue to green. . Similarly, adding manganese to a conventional Zn5-Cu phosphor changes the emission color to yellow-orange. can be shifted to. West German Patent No. 3.011.81.5 (F 1sc (her) “Zinc-cadmium containing magnesium sulfide for blue shift.” claims a long-lived blue phosphor material composed of mu sulfides, but this No absolute value of "long life" to substantiate the claim is given in the patent.

Over the years, seeds have been developed to improve the brightness and half-life of copper-activated zinc sulfide phosphors. Various techniques have been proposed. These techniques often involve one or more Halides (e.g. C1, Br, I) or trivalent ions (aluminum, gas) Co-activators (co-activators, such as lithium, indium, etc.) compounds or complexes vator). For the production method of phosphor for the purpose of improving brightness For example, US Patent No. 3.082.344 (T horn ton ), No. 3,152.995 (S track) and the paper by P eters et al. ( J, Appl, Phys, vol. 34, pp. 2210-2215 (196 See 3)).

A typical electroluminescent phosphor material according to the prior art was prepared via the following steps.

(a) Zinc sulfide is by far the main component, about 1 weight percent electroluminescent activator. (e.g. copper compounds such as Cu5O) and a few percent (by weight) of Preparing a mixture comprising a halogenide-assisted activated flux compound, (b) Firing at a temperature of, for example, about 1000°C to 1300°C: (C) this first firing natural cooling of the fired material to room temperature and washing with water; (d) mechanical response to the first fired material; Force loading (e.g. grinding) + (e) strained powder at high temperature, e.g. For example, baking at approximately 600°C to 950°C: and (f) this Return the second fired powder to room temperature (e.g., remove it from the oven and slowly Either let it cool naturally or cool it slowly and then rapidly. Therefore).

In the method described above, the first firing produces an initial dominant cubic structure of the phosphor precursor. This causes a transition from the dominant hexagonal configuration to the dominant hexagonal configuration. then when it cools down There is some reversion from hexagonal to cubic system, but such reversion is minimal. . The mechanically stressing step pushes even more phosphor back into the original cubic system. back, introducing "defects" into the particles of phosphor material. Second firing and cooling cycle further causes a transition back to the original predominant cubic structure of the phosphor particles.

The phenomenon of a phosphor reverting back to its original dominant cubic structure or atomic arrangement is called phosphorescence. The technique of phosphor is necessary to obtain brightness (brightness or brightness) and longevity. generally accepted in the art. Subsequently, stress is applied (causes distortion) steps to achieve a sufficient level of cubic structure to obtain a commercially useful phosphor. of critical importance in promoting or achieving reversal. such distortion Typically, the first fired material is heated for a standard amount of time, i.e., conventional experimentation and/or Experience shows that the time when maximum illumination is obtained, milling or grinding ( This is achieved by (mulling).

The technology involves a step of crushing the zinc sulfide crystals during the first firing and applying various stresses to them. However, none of these methods are suitable for use with phosphors such as those of the present invention. Sulfide with a long half-life that maintains high initial brightness and sustained high brightness Zinc phosphor material did not result.

Summary of the invention As mentioned above, the present invention relates to electroluminescent phosphors and methods of making such phosphors. Ru. In particular, the present invention provides special control of pre-calcined crystalline zinc sulfide phosphor precursor materials. Concerning long-life phosphors obtained by controlled mechanical deformation.

In phosphor technology, the duration of mechanical stress loading is essential for maximum brightness. is known to be a key parameter of the mechanical stress loading stage.

Generally, the initial brightness of a phosphor product is highest during the initial early period of mechanical stress loading. The brightness increases to a high brightness level, and then decreases as the stress load continues. It is shown. See the paper by Peters et al., supra. electroluminescent phosphor The characteristic time until the product's brightness decreases by half (i.e., half-life) is determined by the mechanical stress load. is a positive function of the time until the brightness reaches its peak. Surprisingly, it was discovered that it includes not only the time of , but also the time after that. this present Elephants, so far as we have been able to find, have not been used to produce electroluminescent phosphors. found to exist for any variation of the parameters used in the process. It was issued.

Furthermore, the brightness of the phosphor is proportional to the duration of the stress load after it reaches its peak brightness. The rate at which the phosphor's brightness tends to decrease effectively reaches its brightness peak It is virtually slower than the rate at which brightness increases in proportion to the stress loading time. discovered. Thus, the present invention exploits the extreme capabilities of pre-calcined phosphor precursor materials. Mechanical stress loads, i.e. for long periods beyond the point at which peak brightness is normally achieved. When subjected to stress, unexpectedly superior properties in terms of brightness and service life (i.e. Made of electroluminescent phosphor with improved half-life without sacrificing much brightness It is based on the discovery that a product can be obtained.

According to the present invention, the critical factors for obtaining improved properties in the electroluminescent phosphor are: , the method of mechanical stress loading of the initially fired phosphor precursor.

As mentioned above, this mechanical stress load consists of the maximum The critical factor is to carry out the process for a long time beyond the point at which light is obtained. .

The specific parameters chosen for the application of mechanical stress depend on the starting material, the phosphor. A form of mechanical stress applied, used to stress the phosphor precursor material. The efficiency or methodology of the equipment used as well as the desired brightness of the phosphor final product. and varies depending on the service life. Regarding starting materials, copper activators are used to a high standard. In addition to producing green phosphor when added at lower levels, copper activators were used at lower levels. It has been found to have a longer service life and higher brightness than similar phosphors. has been done. Furthermore, if a small amount of zinc selenide is added to the starting material, the produced EL The quality of the phosphor, especially in the production of green phosphors with high brightness and excellent long life. It was also found to contribute to benefits.

The method of the invention thus comprises the following steps: (a) mostly zinc sulfide; A mixture containing a small amount of activator, preferably a copper-containing activator compound, is prepared. to make; (b) form particles with overwhelmingly (>50%) hexagonal crystal structure; (c) firing said mixture at a temperature sufficient to Mechanical treatment of the mixture for an extended period of time beyond the point at which maximum phosphor brightness is achieved Applying stress, e.g. grinding in a mortar, crushing or grinding: (d) Mechanical response to revert the crystal structure to an overwhelmingly cubic arrangement. to perform a second firing (second firing) on a substance to which force has been applied; (e) after that, twice. Cool the fired material to produce the desired electroluminescent material with high brightness and long half-life. Obtain a phosphor product.

The present invention is generally applicable to all electroluminescent phosphors, regardless of the color they emit. can, but especially phosphors that emit in the blue, green and yellow parts of the spectrum can be optimally applied to The ultimate luminescent color of the finished phosphor is It also depends in part on the starting materials used. Have normal proficiency in phosphor technology As is well known to people, changes in luminescent color are caused by the composition of the starting materials and their relative properties. affected by changes in quantity. For example, the brightness and color may be different from copper and/or It can be controlled by shifting the content of zinc renide.

In any case, compared to typical comparable phosphors, the A number of improvements and attributes are realized from the phosphors that have been synthesized, e.g. Phosphors produced in Compared to its standard counterpart, which has a half-life of 2000 hours to 10,0 It has a half-life of over 00 hours. Similarly, blue lights made in accordance with the practice of the present invention Electroluminescent phosphors typically have a half-life that is three to five times longer than traditional blue phosphors. have

In addition to the improved phosphors and methods of making improved phosphors described above, the present invention further provides Electroluminescent lamp with excellent longevity and brightness properties Also related to group elements. The improved electroluminescent lamp of the present invention comprises: Phosphor materials produced in accordance with the practice of the present invention can be used in a typical electroluminescent arises from its incorporation into playing cards. These EL clamp configurations and their manufacture The manufacturing method is well known and is described in detail in the patent literature.

Brief description of the drawing Figure 1 shows the electroluminescent lamp used to test the phosphor of this invention. FIG.

Figures 2-6 show the many differences incorporated into the test electroluminescent lamp. Characteristics of each phosphor product, with plotted curves corresponding to each of the phosphor compositions. How the brightness and service life vary as a function of the time of mechanical stress loading during machining. FIG.

Figure 7 shows the brightness and service life characteristics of the phosphor composition V5. Shows the relationship between stress loading time In this case, the method of applying stress is pulverization (+++ulling).

Figure 8 shows zinc sulfide:copper stressed for 20 minutes by mortaring. shows the lifetime characteristics of the phosphor. In this case, the content of Cu retained in zinc sulfide is , was continuously increased stepwise from 0.054% to 0.091%. In addition, for comparison Therefore, the lifetime characteristics of commercial green electroluminescent phosphor are also shown. commercial The retained Cu content of the phosphor of the physical product is 0.08% and 0.054% C according to the present invention. It exhibited a shorter lifetime than U-content phosphors.

Preferred embodiment The methods of the invention are generally applicable to any electroluminescent phosphor precursor material or composition. Can be used. Their compositions are well known and available to those of ordinary skill in the art. easily recognized.

Typical phosphor precursor materials generally consist of zinc sulfide alone or its active combination with the oxidizing agent zinc selenide and one or more co-activators. It consists of A preferred phosphor precursor composition includes a combination of zinc sulfide and zinc selenide. is used. The zinc sulfoselenide mixture generally has at least 80% Preferably 90%, most preferably at least 96% by weight zinc sulfide and selenide. Consists of the remainder of zinc.

Activating agents used in the phosphor precursor compositions of the present invention include: but not limited to. Copper, silver, gold, phosphorus, arsenic, vanadium, antimony lead, tin, manganese, iron, sodium, lithium, gallium, tellurium, Candium, indium, and rare earth compounds. A preferred activator is a single copper compound. alone or in combination with one or more of the above-mentioned inhibitor compounds.

Preferred copper compounds include steel sulfate, copper nitrate, steel chloride, copper bromide, copper acetate, copper fluoride, and iodine. Among them, copper sulfate is most preferably used. general In addition, the activator is quadruple based on the aforementioned zinc sulfide or zinc sulfoselenide substances. % by weight or less, preferably about 1% by weight or less.

Coactivators that can be used in the practice of this invention include halides (C1, B r.

■) and trivalent ions (Al, Ga, In, etc.). . Preferred co-activators include halide-based complexes, most preferably is a halide flux. Suitable co-activators can be identified by those of ordinary skill in the art. It is well known to those who have it. Representative examples of suitable coactivators include barium bromide, Magnesium, sodium bromide, magnesium chloride, ammonium bromide, sodium chloride Thorium, barium chloride, magnesium iodide, ammonium iodide, barium iodide , sodium iodide, etc. Generally, co-activators include, for example, magnesium chloride. It exists in a hydrated form, such as MgC1□6H20. The auxiliary active inhibitor component is It consists of one or more co-activators, the amount of which is generally used is zinc sulfide or 20% by weight or less, preferably 1% by weight based on the weight of zinc sulfoselenide 0% by weight or less, most preferably about 8% by weight or less.

As previously mentioned, the phosphor precursor mixture or composition, if desired, may be supplemented with additional ingredients. It can be added or incorporated into a mixture. Their additional ingredients include zinc sulfate , zinc oxide, sulfur, etc., but will be readily known to those skilled in the art. .

The exact reasons for the improved results obtained by the applicant's method are still unclear. Although not fully understood, the results are clear. When it emits light in the green part, it has a half-life of more than 2000 hours, and it is the blue part of the spectrum. When emitting light, a zinc sulfide phosphor with a half-life of over 1000 hours is applied. Both represent dramatic improvements over existing comparable luminescent phosphors. are doing.

Briefly, the present invention starts from the aforementioned phosphor precursor materials or compositions. Ru. Preferably, the mixture comprises cubic or predominantly cubic zinc sulfide. a copper activator, such as copper sulfate, and at least one halide flux, e.g. , chloride flux or bromide flux). This pioneer group The composition converts the cubic arrangement of zinc sulfide into a dominant (>50%) hexagonal arrangement. It is fired at a temperature and time sufficient to convert the The appropriate temperature and time for this firing are It will be readily apparent to those of ordinary skill in the art. Typically, the first Calcination is at least about 1000°C, preferably at least 1100°C, most preferably The process may be carried out at a temperature of at least about 1200°C. However, the maximum firing temperature will generally not exceed 1400°C. The phosphor precursor material is fired The time of exposure will vary depending on the precursor material and the calcination temperature itself. general The first baking time is about 1 hour to 6 hours, preferably about 2 hours to about 4 hours. It will be. In this specification, including examples, all references to firing time refer to the temperature of the material. Phosphor precursor material or phosphor from the time the temperature reaches the firing temperature until the firing is completed It should be noted that this should be understood as referring to the actual firing time is necessary. Therefore, the actual residence time in the furnace will vary until the phosphor reaches the desired firing temperature. If you include the time it takes to do this, it will probably be a little longer than the baking time.

After firing, the first fired material was cooled for further processing. room temperature cooling or In either forced cooling, some of the crystalline zinc sulfide becomes hexagonal during the cooling cycle. The configuration will revert back to the cubic configuration.

The first calcined material is then passed through a mortar-grinder, such as Retsch Gmb of West Germany. The time required to obtain maximum brightness in the mortar grinder made by H, model RM○ ( Tb) was milled or mortared.

Tb can be easily determined through simple and undue experimentation for any given phosphor composition. are well known in the art for determined and/or standard phosphor compositions. . The purpose of the extended milling process is to produce highly fractured zinc sulfide crystals. That's true.

Phosphors are typically valued by their brightness, so if they are finely ground, they can be It is known that lead particles will cause defects or breakage in their crystal structure. However, prolonged pulverization for extended periods of time is harmful and can cause maximum Do not cause major defects or damage that exceeds the degree of pulverization at which brightness is obtained. I was believed. However, unexpectedly, long-term grinding and subsequent removal of zinc sulfide Inducing a high degree of defects or breakage in the crystal results in minimal brightness. It has been found that the phosphor has a much better service life with only losses. It was.

In addition to producing more highly damaged or defective zinc sulfide crystals, Grinding is the same (and also changes some of the zinc sulfide crystals from a hexagonal arrangement to a cubic arrangement). and, perhaps more importantly, milling subsequently transforms the higher range of crystals into Phase transition, i.e. from hexagonal to cubic arrangement developed by the second firing step. It appears to facilitate phase transition. Also, long-term grinding is probably more This results in a uniform and small particle size, which makes electroluminescent lamps Although desirable from the standpoint of phosphors useful in manufacturing, otherwise It is believed that a considerable amount of ash has been removed.

The amount of time the first fired material is mechanically stressed is determined by the material itself. depending on the final properties and properties and the mechanical stressing technique or methodology used. Ru. Typical methods of applying stress include grinding with a mortar, mortar, etc.) , mixing-grinding, ball milling, fluid energy grinding, jet pulverization, grinding, Includes vibratory milling, centrifugal milling, hydrostatic pressure, -axial or biaxial pressure, etc. Furthermore, this The term also refers to mechanical It is also intended to include methods of applying stress. I haven't tried it yet, but measures that most reliably impose mechanical stress on individual particles in the process. It also includes methods of subjecting materials to wax thermal shock or other shocks.

Additional activators, co-activators simultaneously with or after the mechanical stress loading step , or other auxiliary components can also be added to the in-process phosphor mixture. That's it additives or dopants (as they are often called) are defined as It is a thing. Generally, an additional activator, preferably a copper activator, may be used alone or is preferably added in combination with other auxiliary ingredients. The code used at this point is A preferred combination of -pants includes copper sulfate and zinc sulfate. Generally, within the process The amount of activator added to the phosphor is based on the total weight of phosphor in the process. It will be about 0.5% to about 5%, preferably about 1% to about 3%. Use of activator Lower doses may be used, but lower doses will reduce the brightness and service life of the final composition. It is unlikely that there will be much improvement. However, using less activator Such compositions will still have superior properties to conventional phosphors. similar More activator can be used, but more than 5% (by weight) The amount is above the saturation point of the composition and generally has no effect on brightness and/or longevity. does not provide any further improvement.

Regarding auxiliary ingredients, the auxiliary ingredients preferably account for the total weight of the phosphor in the process. As a standard, it is used within the range of about 1% to about 20%, preferably about 1% to about 16%. used. As previously mentioned, dosing added during or after the first firing stage A preferred combination of punts consists of copper sulfate and zinc sulfate.

The dopant-doped mixture is then heated to a temperature lower than that of the first firing, typically , at a temperature below about 1050°C, preferably below about 900°C. most Preferred second firing temperatures range from about 750°C to about 800°C. Perform the second firing The aging time generally depends on the firing temperature, the material itself and the properties desired in the final phosphor. It will depend on the nature. Generally, the firing time is such that the crystal structure changes from a hexagonal arrangement to This is sufficient time to completely revert to the square configuration. This time is generally 17 2 to 3 hours or more, more specifically about 1 to 2 hours It is.

After the second firing, the phosphor material is cooled at atmospheric pressure or by induction cooling or quenching. cooled down. The phosphor particles then remove the excess activator from the surface of the zinc sulfide crystals. , that is, treated or cleaned to remove copper compounds. This cleaning is done using the relevant technology. This can be done by any method known to those skilled in the art. Such cleaning methods are sequential and multiple washings using hydrochloric acid (4N), water, and 4% sodium cyanide solution.

After washing, the phosphor material is dried.

After drying, the phosphor is preferably passed through a 325 ml sieve to remove all excess large Remove phosphor particles. High brightness and long life even with unsieved phosphor The grains are preferred to ensure a good phosphor layer in its composition. Manufacture of electroluminescent lamps with tight tolerances regarding child size It is not very suitable for use.

In addition to the foregoing steps, further steps or manipulations may be performed at various times within the foregoing process. You can also do it in points. For example, after the initial firing, the phosphor being processed may be washed with water. Excess co-activation containing ions generated by calcination, especially excess halogen ions It may be desirable to remove the agent. This wash is repeated using hot deionized water. The conductivity of the cleaning water is below a certain level, preferably about 50 microns. It will progress to less than ohm cm-'. In addition, a second step is used to remove excessively large particles. It is desirable to screen the unfired material. Generally, at this stage, Preferably, a 100 meter screen is used for sieving purposes.

While not wishing to be bound by any theory, the process of this invention In combination with initial firing at high temperatures and excessively long mechanical stress loading times, Phosphor material particles with a high degree of defects or breakage in the crystal structure as well as hexagonal Phosphor compositions containing higher levels or percentages of cubic than cubic configurations It is believed that a product can be obtained. The number of breaks or defects in the zinc sulfide crystal grains is If the number increases, the number of sites where the copper compound, which is an activator, will be deposited will increase during the second firing period. It is believed that

Doping the first fired material with additional copper activator will increase the number of defects in the crystal structure. Or the damage tends to be more likely to be saturated by copper compounds. clearly, When the amount of copper activator in the in-process mixture is at very low levels, copper compounds may form. The chance or possibility of penetrating breaks or defects in the crystal structure is reduced by high levels of copper activators. It will be less than when using . In general, copper is present from the beginning and copper is added later. The added copper is retained in the phosphor at a sufficiently high concentration during the two firing stages so that it is not washed away. The total content of copper retained in the future final product is at least 0.02% by weight, preferably preferably at least 0.06% by weight. Generally, the total copper retention content of the phosphor is Preferably from 0.4% to about 0.25%, most preferably about 0.25%, by weight. It ranges from 0.006% to about 0.02%. Subject to the foregoing limits, in accordance with the practice of the invention: The compositions produced generally provide phosphors with high initial brightness and long half-lives. I can do it.

Several series of electric fields were used to determine the effect of milling time on phosphor performance. Manufacture a luminescent phosphor and an electroluminescent lamp for testing using the phosphor did. Each series includes a method for producing electroluminescent phosphors and/or a pioneer in phosphor production. They differ from each other due to slight variations in the composition of their body substances. of each series In this study, the phosphor and its manufacturing method were kept the same, and the grinding time of the phosphor was varied. Ta. Samples of each phosphor were then placed in five electroluminescent lamps. installed and tested the lamp.

The EL test lamp (shown in FIG. 1) was manufactured as follows. electroluminescent phosphor A paste was prepared by dispersing the powder in a dielectric (i.e., nonconducting) resin. .

A layer 30 of paste containing phosphor powder and a layer 34 of barium titanate paste. , an opaque metal foil (aluminum foil) serving as the rear electrode 20 and a transparent front electrode ( (indium tin oxide) 22. on top of the transparent front electrode 22 A desiccant layer 24 was formed to cover the electrodes. A pair of lead wires 26 and 28 They were connected to the front electrode 22 and the rear electrode 20, respectively. Extending outward from this assembly A protective film 32 covers the entire assembly except for the lead wires 26 and 28 that are attached to the lamp. It is encapsulated to provide physical support and a moisture barrier. of the phosphor layer 30 The thickness is 0.04 mm. The thickness of the barium titanate layer 34 is 0.015 mm. It is.

A more detailed description of the construction of electroluminescent lamps can be found in U.S. Pat. No. 4.104.555 (Fleming). This patent The disclosure is herein incorporated by reference.

The general manufacturing method of phosphor materials as described above will be referred to as the cited method from now on. Make it.

In the examples below, the brightness (or brightness) of each test lamp was 115 volts, 400 volts. Measured in Hertzian excited state. Brightness and service life data for each phosphor produced The data points are the brightness and service life measured for each of the five test lamps per group. It was determined as the average value of lifespan. Electroluminescent phosphor (or the same phosphor The half-life of a lamp (including the body) is the period when the initial brightness (Bo) decreases to 172 of its initial value. It is defined as the time it takes to reach a certain point. This amount of time may reach several thousand hours. Therefore, accelerated service life testing is almost inevitable. One such test method is the English devised by the National Aeronautics and Space Administration, it uses elevated temperatures and frequencies. Consists of driving a ramp under. This method is described by R.H. Marion et al. Paper, “Analysis of service life and powder method electroluminescent phosphorescent materials”, E1electroluI Ilinescene, S hinoya, S, and Kobayash i, H,, ed., S pringer-Verlag, 332 pages, 1989 It was written in the year.

The accompanying figures are constructed in accordance with the practice of the invention as set forth in the Examples below. It represents the brightness and service life data realized from the evaluation of various phosphors.

Figures 2-6 show service life and brightness vs. for compositions made in accordance with the practice of the present invention. .

It is a graph showing the relationship between grinding times. Figure 7 shows that in mortaring It shows the effect of mulling on brightness and service life. Figure 8 is , demonstrating the effect of various levels of copper retained in phosphor materials on service life. Show data. Figures 2°3 and 6 are based on actual service life test data.

All other figures show service life data based on the results of accelerated service life tests.

Figure 2 shows the actual data points of brightness achieved and lifetime, while Figures 3-7 show the target Normalized brightness and lifetime data, i.e. a data point indicating the maximum level measured. Comparative numerical values are shown when each count is set to 1.0.

The examples given below are intended to aid in understanding the invention and are This should not be considered to limit the invention. Phosphor precursors unless otherwise specified All amounts for various components of body materials and in-process additives are expressed in parts by weight. It is. All temperatures are expressed in degrees Celsius (°C).

A series of compositions consisting of phosphor materials that emit at the fringes of the visible light spectrum are described below. Prepared according to the procedure.

98 parts zinc sulfide, 2 parts zinc selenide, 03 parts copper sulfate (anhydrous), 3 parts odor Barium chloride (hydrate), 3 parts magnesium bromide (hydrate) and 2 parts sodium bromide Tri-blend the mixture in an I-blender for at least 30 minutes.

Next, put the blended ingredients into a quartz crucible, cover it, and heat it at 1200℃ for 3 hours. Baked for a while. After firing for 3 hours, remove the crucible from the furnace and blow cold air into the bottom of the crucible. I put it on and cooled it down quickly. Once the phosphor has cooled, ions, especially bromide ions, Wash with hot film iodine and water at least 6 times until the conductivity of the washing water reaches 5. It was set to 0 micro ohm Cll1-1 or less. The phosphor is then filtered, It was dried and sorted through a 100 sieve sieve. obtained at this stage of the process The substance will be referred to as the first fired substance.

Next, two aliquots of the first fired material are each We decided to grind 00 grams at various grinding times and demonstrate the effect.

In this example, milling times of 0,5,10,20,30,40 minutes were used.

Each ground sample was then treated with 5 grams of copper sulfate (CuSO4) and 32 grams of sulfur. Zinc acid (ZnSO4) doped and blended in a capped quartz crucible It was baked at 800°C for 1 hour. After this second firing, the phosphor is cooled and then continued The phosphor was washed with hydrochloric acid (4N), water, and finally a 4% NaCN solution. All excess copper compounds found on the surface of the particles of material were removed. Then, The phosphor was dried, sieved through a 400 mesh screen, and electroluminescent. Processed into a Nessent lamp.

Brightness levels and half-lives obtained for various samples made according to this example. The data representing is depicted in Figure 2 above. As shown in the figure, the brightness (curve 35) peaks at about 5 minutes of grinding time, while the half-life (curve 36) The grinding time continues to increase until it reaches 30 minutes. Furthermore, after the brightness has passed its peak, Although it decreases as the grinding time progresses, the rate of decrease is at the initial stage of grinding. The rate of increase is much slower. Based on this data, the phosphor peaks in brightness. It is clearly beneficial to grind for more than 5 minutes, and it also reduces the brightness. Substantial increases in half-life can be obtained at the cost of minimal losses. same The same plots are depicted in standardized form in Figure 3 as curves 41 and 42, respectively. The procedure of Example 1 was followed except that the temperature of the second firing was 750°C instead of 800°C. A second phosphor composition was therefore prepared. Is the composition of this phosphor a compounded formula? The difference is that zinc selenide was removed from Example 1, and the same weight was used instead of magnesium bromide in Example 1. It is slightly different from the composition shown in Example] in that the composition was replaced with a small amount of magnesium chloride (hydrate). It's very different. Brightness and lifetime data for this phosphor sample are , are shown in standardized form in curves 45 and 46, respectively, of FIG.

Example 3 Example 1 except that the copper sulfate starting material was increased from 0.03 parts by weight to 0.04 parts by weight. A composition of phosphor material was prepared following the same procedure. Upon grinding of this phosphor composition The luminance and service life data as a function of the curves 51 and 52 are shown in Figure 4, respectively. It is expressed as

Example 4 A phosphor composition that emits in the blue part of the spectrum was prepared according to the procedure of Example 1. Ta. This time, the difference from Example 1 is that the level of copper sulfate was changed from 0.30 parts by weight to 0. ．． 15 parts by weight, and three types of fluxing agents (barium bromide (hydrate), barium bromide (hydrate), 1 part by weight of ammonium bromide instead of gnesium (hydrate), sodium bromide) 1 part by weight of sulfur was added as an auxiliary component.

The brightness and lifetime data of the prepared phosphors are shown in Figure 4 as curves 55 and 56, respectively. It is depicted as

Example 5 An additional series of phosphors were prepared using the same procedure as in Example 1. Different from the case of Example 1 The point is that the starting materials are wet mixed by adding water, and then the moisture is removed by heating and drying. The second firing was performed at a temperature of 750°C. Furthermore, examples 1, with the same weight of magnesium chloride (hydrated) instead of magnesium bromide. A slight modification was made by replacing it with (object). Measurement data of brightness and lifetime of prepared phosphors The tap points are depicted in FIG. 5 as opposing curves 61 and 62.

Example 6 A series of phosphor compositions were prepared following the general procedure of Example 1, with the exception of the present The firing time was changed as shown below, and magnesium bromide (hydrate) was replaced. The same weight of magnesium chloride (hydrate) was used as a fluxing agent. Curve in Figure 6 The first series of phosphors represented by curve 71 (brightness) and curve 72 (lifetime) is Both the first firing and the second firing were fired for 2 hours. On the other hand, curves 75 and 76 are exceptions. A similar series of phosphorus with a first firing of 2 hours and a second firing of 4 hours. FIG. 2 is a plot corresponding to the behavior of luminance and service life of a light body. As shown in Figure 6 , again, despite various changes in the conditions of the phosphor manufacturing method, these For all of the changes, the benefit of grinding beyond the grinding time that gives maximum brightness. The benefits are as clear as last time.

Example 7 A series of phosphor compositions similar to those described in Example 1 according to the method of Example 1 I prepared something. The exception this time is that the starting material is ground (mortari) after the first calcination. ng), but fine pulverization (mulling) L, second firing at 750℃ That's what happened. The pulverizer used was manufactured by National, Chicago, Illinois. S Impson Mix M made by Engineering Company uller, model LF, style UD. This device is connected to the center of the mandrel. and two heavy crushers mounted on the ends of a horizontal shaft which rotates in a horizontal plane. It consists of a turret wheel. The sweaver wheels the material to be pulverized push it under.

As shown in Figure 7, the phosphor produced according to the above teachings was The maximum brightness is shown in (curve 81). Phosphor composition exceeds the peak period of 30 minutes Keeping things pulverized results in phosphors that have a longer service life with minimal loss of brightness. (curve 82). This example uses another method to mechanically stress the phosphor material. This demonstrates the fact that the method can also be used to implement the present invention. kind of mechanical Stress loading methodologies may take longer to achieve the same results right. Nevertheless, improved phosphor compositions can still be obtained by practicing the present invention. Electroluminescent lamp with enhanced brightness and long lifespan You can get

Example 8 A series of phosphor compositions were prepared according to the methodology of Example 1 and the formulation of Example 1. Ta. As an exception, this time the amount of copper added at the beginning was set to 0. ．． 06%, 0.08%, 010%, and 0.12% (all % by weight) of phosphor The composition was changed to give a composition of as a function of copper content and milling time The brightness and half-life data for actual lamps are shown in Table I.

Grinding time, initial brightness, half-life %Cu (minutes) (Ft-L) (hours) 0, 06 0 18.9 150 20 23, 2 1900 0, 08 0 9.6 200 20 20, 1 4900 0, 10 0 9.4 250 20 24, 6 6150 0, 12 0 9.5 500 5 27, 5 3200 10 25, 3 5300 20 22, 5 5650 30 19, 3 7700 40 17, 5 7600 note) Ft-L is an abbreviation for Foot-Lamberts. Ground samples always have higher initial brightness and longer half-time than unground samples. It showed a decline. The half-life was the same (and improved as the copper content increased.30 The brightness of the sample ground for 10 minutes decreased slightly when the copper content was 0.12%; However, it subsequently showed a very good half-life.

The relationship between brightness and lifetime versus copper content is shown in Table H and depicted in FIG. same Figure 8 shows a typical commercial product green with a retained copper content of 0.08%. Phosphor plots are shown. EL clamp brightness after 600 hours of operation was only 66% of the initial brightness level.

Initial operating time (Hours) Weight Brightness 19th ±"-1 Kai-12" Town J Prisoner of Work 0.06 22.7 1Q1.981 04.9 10 (1,988,981,776,47Q, 50.08 19.9 101.0 100.5 98.8 g3.5 90.5 88.0 84. 70.10 23.5 101.2 102.3 100.9 96.0 92 ．． 5 90.5 g7.20.12 22.8 100.9 103.1 10 2.1 96.4 93.3 91.9 87.9 Operating hours (Hours (Continued from) Weight 1 (state Danfu rules shellfish vine H deaf league Karhie Wangji 0.06 64.7 61 ．． 5 59.6 56.4 53.8 51.5 48.8 47.3 26. 50.08 80.0? 9.9 78.1 75.4 73.6 71.1 70.7 69.0. 4g, 70.10 83.7 83.4 81.2 7 9.7 76.5 76.1 73.5 72.8 53.40.12 g2. 5 82.8 80.5 78.2 77.9 75.2 73.3 71.9 51.7 The invention has been described above in detail, including preferred embodiments. deer However, after reading the disclosure of this specification, a person skilled in the art would be able to understand the following Without departing from the scope and spirit of this invention as set forth in "Scope" (various modifications and It will be readily recognized that/or improvements can be made.

FIG.1 FIGB FIG. 5 Floating 1 season (Kariooo Hat 1 season) FIG 8 Summary 1 A mixture consisting mostly of zinc sulfide with small amounts of thermostatic inhibitor compounds and fluxing agents, First, a first firing is performed at about 1200° C. to form particles having a hexagonal crystal structure. this the first fired mixture for a time exceeding the stress loading time at which its maximum brightness is obtained; Grind or otherwise apply mechanical stress. This material was heated at about 750°C. Calcinate for 2 hours and cool to obtain phosphor powder. Various phosphors and different grinding times produced a large number of electroluminescent test lamps. each manufactured For these phosphors, the brightness increases as the grinding time increases and reaches a peak. , decreased, but the service life was proportional to the grinding time longer than the point at which the brightness decreased. It showed an increasing trend. Excellent combination of brightness and service life required for maximum brightness Obtained by grinding for more than the required time.

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Claims (1)

[Claims] 1. (a) Phosphor precursor consisting mostly of zinc sulfide with a small amount of copper activator compound preparing a mixture of body substances; (b) first firing the mixture to form particles having a primarily hexagonal crystal structure; ; (c) mechanically stressing the first fired material to produce a crystalline powder; A portion of the powder is converted into a cubic structure by the stress loading, and the mechanical stress loading (d) continues beyond the time at which the maximum brightness of the final product phosphor is achieved; After that, the stress-loaded crystal powder is fired to change the structure of the crystal powder to a mainly cubic system. and (e) cooling the subsequently fired powder; A method for producing an electroluminescent phosphor having a long service life, comprising (a) to (e) of 2. The time to apply the stress is short enough to achieve the maximum brightness of the final phosphor. 2. The method according to claim 1, wherein the increase is at least 1.25 times. 3. Additional copper activator alone during or after the mechanically stressing step or added to the mixture in combination with co-activators or other additives. The method described in paragraph 1. 4. Claim 3, wherein an additive is used, and the additive is zinc sulfate. the method of. 5. the first calcination is carried out at a temperature of at least 1100°C; the second calcination comprises: A method according to claim 1, which is carried out at a temperature of 900°C or lower. 6. the first firing is performed at a temperature of about 1200°C or higher; 2. The method of claim 1, wherein said step is carried out at a temperature of about 800 DEG C. or less. 7. The amount of copper activator compound is about 1% or less based on the weight of zinc sulfide. A method according to claim 1. 8. The method according to claim 1, wherein the phosphor precursor material further comprises an auxiliary activator. Law. 9. 9. The method of claim 8, wherein the co-activator is a halide flux. 10. To remove any excess coactivator to the coactivator ions, 9. The method of claim 8, further comprising the step of washing the unfired material. 11. The person according to claim 1, wherein the phosphor precursor material further contains zinc selenide. Law. 12. Powdered electroluminescent material produced according to the method of claim 1. phosphor. 13. A powdered electroluminescent material produced according to the method of claim 8. phosphor. 14. (a) a phosphor consisting mostly of zinc sulfide with a small amount of copper activator compound; preparing a mixture of precursor materials; (b) first firing the mixture to form particles having a primarily hexagonal crystal structure; death; (c) mechanically stressing the first fired material to produce a crystalline powder; A part of the crystal powder is converted into a cubic crystal structure by the stress loading and the machine The stress loading is continued beyond the time when maximum brightness of the final product phosphor is achieved. ; (d) After that, the stress-loaded crystal powder is fired to mainly change the structure of the crystal powder. (e) cooling the fired crystal powder; (f) dielectric sandwiched between the rear electrode and the optically transparent front electrode; forming a laminate using a layer of said second fired crystal powder dispersed in a resin; ;and (g) connecting a pair of conductive lead wires to the rear electrode and the front electrode, respectively; A method for manufacturing an electroluminescent lamp comprising the above (a) to (g). 15. The mechanically stressing time is such that the maximum brightness of the final produced phosphor is achieved. 15. The method of claim 14, which takes at least 1.25 times as long. 16. Additional copper activator alone during or after the mechanical stressing step , or added to the mixture in combination with co-activators or other additives. The method described in box 14. 17. Claim 16: An additive is used, and the additive is zinc sulfate. Method described. 18. said first firing is carried out at a temperature of at least 1100°C; said second firing is carried out at a temperature of at least 1100°C; 15. The method of claim 14, which is carried out at a temperature of 900°C or lower. 19. the first firing is performed at a temperature of about 1200°C or higher; Claim 14, wherein the calcination is carried out at a temperature of about 800°C or less. Method. 20. The amount of copper activator compound is about 1% or less based on the weight of zinc sulfide. 15. The method according to claim 14. 21. 15. The method according to claim 14, wherein the phosphor precursor material further comprises a co-activator. Law. 22, (a) rear electrode; (b) optically transparent front electrode; (c) an electroluminescent phosphor dispersed in a layer of dielectric resin; Consisting of copper doped zinc sulfide prepared according to the method described in item 1, a phosphor comprising a dielectric resin layer sandwiched between the rear electrode and the front electrode; ;and (d) a pair of conductive lead wires connected to the rear electrode and the front electrode, respectively; An electroluminescent lamp comprising the above (a) to (d). 23. The copper-doped electroluminescent phosphor has a maximum brightness of the final phosphor. Mechanically stressed for at least 1.25 times the time achieved An electroluminescent lamp according to claim 22.