SU690660A1 - Method of manufacturing electroluminescent screen - Google Patents

Description

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The invention relates to electronic engineering and lighting engineering, in particular, to methods for producing electroluminescent matrix or mosaic screens based on powder electroluminescent materials that are excited by a constant electric current (ELPT).

It is known that in any method of manufacturing electroluminescent screens (EL screens) a powder layer B is applied to a substrate with electrodes, and an opaque metal electrode is applied to its surface.

The pulverization method is widely used to fabricate EL layers excited by alternating field 1. It is not suitable for producing EL layers excited by a constant field, since with low binder contents the suspension becomes unstable and the layers are loose and uneven, and In layers with a high binder content (dielectric), it is impossible to obtain high brightness, since brightness is proportional to the current flowing through the electroluminescent powder.

The casting method makes it possible to obtain layers with weight filling by the phosphor in the ratio of 5: 1, which is insufficient for an ELPT (a ratio of 20:: 1 is necessary) 2.

Also known electrophoretic method, allowing to apply the EL layer without bonding. In the electrophoretic method, fine particles are preferably deposited. The application of the fine fraction of the electroluminor is due to the fact that the electrophoresis is carried out from the bottom up, i.e. the electrophoretic and sedimentation sedimentation rates of the particles are directed in different directions 3.

For small amounts of binder, the roughness of the EL layer depends on the size of the powder particles and the metal electrode sprayed in vacuum on a rough surface has cracks and tears, which drastically reduces the reliability of the device.

The closest solution to the technical essence and the achieved result to the invention is the sedimentation method of making a screen with a layer of electroluminophore excited by a direct current 4.

The manufacture of the screen by means of sedimentation deposition consists in the following: a thin layer of varnish is applied on a glass substrate with a conductive layer, dried slightly, then an electroluminescent layer is deposited on the substrate. The deposition is carried out by placing the substrate in a well mixed and spaced to remove coarse particles from the layer, an electroluminophor suspension. The substrate is kept in this suspension for 0.5-1 min, then the suspension is quickly sucked off and the sample is subjected to the substance. The dried sample is compacted with a pressure of 300-400 kg / cm and dried at room temperature for 15-20 hours. Thereafter, a lacquer layer is re-applied over the EL layer, polymerized, and then an opaque electrode is applied. The disadvantage of this method is that when the substrate is lowered into the suspension vessel and when it is rapidly aspirated, vortex flows appear that cause uneven coating thickness and, correspondingly, luminance intensity.

The described method has the following disadvantages:

1. Double application of lacquer and its drying dramatically lengthens the technological cycle of manufacturing the screen and reduces labor productivity.

, 2) Applying varnish on a conductive substrate makes it difficult to directly contact the grains of the electroluminescent material with the electrodes. In this method, the electroluminor is not fully used, since the coarse fraction settles to the bottom of the vessel, and a part is removed during suction.

The aim of the invention is to save the phosphor, increase the brightness and improve the uniformity of the emission of the EL screen.

For this, in the method of manufacturing an electroluminescent screen consisting in forming an electroluminescent layer of a substrate With an electrode for nyteM sedimentation, impregnation of a binder, compaction and polymerization, a new piece is first applied to the substrate with electrodes with a portion of a fine phosphorus fraction by electroshore from a solution of an oxidase oxygen dispersed electrode; and then on the obtained fine layer, the same suspension is sedimented until it is completely precipitated. The seal is made with a pressure of not more than 1 kg / cm2. This pressure reduces the amount of scrap on the layer, since there is no stratification and cracking of the substrate, thereby increasing the percentage of yield of screens.

As a result of the formation of the EL layer by electrophoresis, then sedimentation followed by impregnation with a binder and compaction, it is sufficient to compact the EL layer with a pressure of not more than 1 kg / cm 2 rather than 300-400 kg / cm as in the known methods.

The presence of a large fraction in the middle of the layer reduces the number of grain contacts

690660

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in the layer, which leads to a decrease in the total resistance and an increase in the passage of current, and hence the luminance of the EL layer. The brightness of the EL screen, manufactured by the proposed method (if the thickness of the electroluminescent layers is the same) by 10 -

15% higher than the screens manufactured by known methods.

FIG. Figure 1 shows the first stage of panel manufacturing (precipitation of the fine fraction during electrophoresis); FIG. 2 - sectional panel construction.

Example. First, a fine electroluminescent fraction is applied to a glass substrate 1 with transparent strip electrodes 2 in two or five monolayers - by electrophoresis from a suspension of polydisperse powder in isopropyl alcohol (Fig. 1). Then, sedimentation deposition of the same suspension is performed on the entire surface of the screen, as in electrophoresis, until the electroluminor is completely deposited, so that fine fraction 3 of electroluminophore settles on the layer surface.

The fine fraction of the electroluminescent powder at the transparent electrode (on

strip electrodes) will have the maximum number of contacts of contact with the electrode, which ensures high brightness of the EL-layer, and

the fraction of the powder on the surface of the layer reduces the roughness, increasing the quality and reliability of the opaque electrode. The coarse fraction is enclosed in the middle of the EL layer. The thickness of the electrophoresis EL layer is 3-5 µm, and the total thickness of the EL layer usually lies within 20

50 microns -

The fabricated structure of the EL layer (Fig; 2) consists of a glass substrate 1, a transparent electrode 2 SnOj. or ZniOj, fine fraction of the anode memory, coarse particles 4 in the middle of the layer, fine fraction 5 on the surface of the EL layer, metal electrode 6, is impregnated with a binder solution (varnish that holds the powder grains together.

After evaporation of the volatile components of the varnish (15 min), the EL layer is compacted with a pressure of at least 1 kg / cm to obtain a more dense and smooth layer and the binder is polymerized. An opaque metal electrode (e.g., aluminum) is then applied. .

Thus, it was possible to obtain matrix EL screens with high brightness, improved uniformity of luminescence across the field, and a reliable second electrode.

Claims (4)

The use of the proposed method of using an EL screen from a suspension of polydisperse powder by electrophoresis and precipitation provides the following advantages compared to existing methods: increase in brightness by 10-15% due to reduction in the total resistance of the layer when using large-scale electroluminophore; the elimination of vortex flows improves the uniformity of the glow across the screen field and increases the percentage of usable EL screens; increase in labor productivity by 6-8 times due to reduction of the technological cycle of screen manufacturing (absence of double application of lacquer and its polymerization); reducing the consumption of expensive electroluminescent material through the use of all its fractions. In the known methods up to 40% of the electroluminescent material is used, in the proposed method 90%; the possibility of producing an EL screen without the additional cost of electroluminescent powder fractionation. Claim 1. A method of manufacturing an electroluminescent screen, comprising forming an electroluminescent layer on a substrate with electrodes by sedimentation, impregnating a binder, compaction and polymerization, characterized in that, in order to save phosphor and increase brightness and uniformity of screen luminescence, first onto the substrate with electrodes are applied to a portion of the fine fraction of the phosphor by electrophoresis from a suspension of a polydisperse powder, and then the same suspension is sedimented onto the resulting finely dispersed layer Suspension until complete precipitation: 2. The method according to p. I, characterized in that the seal is produced with a pressure of not more than I kg / cm. Sources of information taken into account in the examination 1.Derkach V.P., Koreunsky V.M. Electroluminescent devices. “Naukova Dumka, Kiev, 1968. 2. Application electroluminescence, under. ed. Fock M.W.M., “Owls. radio, 1974. 3. Lavrov I. S., A report summarizing the published works submitted for the degree of Doctor of Engineering. Sciences LTI Lensoveta, 1967. 4. Luminescent materials and high-purity substances, Coll. works, vol. 13, Stavropol, 1975, p. 97-99.