Conductive light-shielding film for low-light-level image intensifier phosphor screen substrate and preparation method thereof

Abstract

The present invention discloses a conductive light-shielding film for the substrate of a low-light-level image intensifier screen and a preparation method. The conductive light-shielding film is positioned between the substrate and the stepped cylindrical surface of the optical fiber panel. The film is composed of gold and silver in a mass ratio of 9:1. The preparation method comprises: preparing a gold paste organic liquid, placing the optical fiber panel to be coated in a coating fixture; activating a rotary motor to rotate the optical fiber panel to be coated, and using a dedicated brush to apply the gold paste organic liquid to the junction of the substrate and the stepped cylindrical surface of the optical fiber panel; after coating, removing the optical fiber panel; placing the optical fiber panel coated with the gold paste organic liquid in a panel sealing furnace, activating a high-temperature baking process for sintering; cooling the panel sealing furnace, removing the optical fiber panel, and inspecting the appearance quality of the sintered film layer. The present invention effectively eliminates optical feedback caused by phosphor emission and improves image intensifier background noise.

Description

Technical Field

[0001] The invention belongs to the field of low-light-level image intensifier manufacturing, and in particular relates to a conductive light-shielding film used for a fluorescent screen substrate of a low-light-level image intensifier and a preparation method thereof. Background Art

[0002] The low-light image intensifier is the core component of the low-light night vision device. It is a high-vacuum device. It is mainly composed of a low-light image intensifier tube (hereinafter referred to as the image tube) and a high-voltage power supply. The structure of the image tube is shown in the attached figure. Figure 1 As shown, the image tube consists of a cathode input window, a microchannel plate, a tube shell, a phosphor screen and an optical fiber panel output window.

[0003] Working principle of image tube: When a weak optical image is formed on the photocathode of the image tube, it is converted into a corresponding electronic image by the photocathode. The electronic image is multiplied and amplified by the microchannel plate, and then accelerated by the anode high voltage to bombard the fluorescent screen to convert it into an optical image with enhanced brightness. Finally, it is output through the fiber optic panel of the image tube to form an optical image visible to the human eye for observation and identification.

[0004] In the functional structure of the image tube, the phosphor screen is the component that converts the enhanced electronic image into a visible optical image. The phosphor screen is manufactured by evenly coating the phosphor material on the optical fiber panel sealed with the metal flange. The conductivity and light-shielding properties of the phosphor screen base of the image tube will directly affect the performance and quality of the image tube. Since the resistivity of the phosphor material is between 10 10 ~10 14 Ω·cm is almost an insulating medium. In addition, the optical fiber panel is also an insulating medium, so the entire fluorescent screen is insulating.

[0005] When a picture tube is operating, electrons emitted from the photocathode are accelerated and focused onto the phosphor screen by a high-voltage electric field. The energy of these electrons excites the screen to emit light, causing it to heat up and generate secondary electrons. Due to the high resistance of the luminescent material, these secondary electrons cannot be promptly conducted away from the screen and instead accumulate there, negatively charging it. This continuous accumulation of negative charge on the screen gradually creates a localized high-potential field, producing bright background spots and even interelectrode discharge, which can damage the screen and lead to a low yield of picture tubes.

[0006] The fluorescent screen assembly uses glass to seal the metal flange and the optical fiber panel together. Since both the glass and the optical fiber panel have a certain degree of light transmittance, when the image tube is working, external stray light enters the image tube through the edge bevel of the optical fiber panel / glass screen (the glass seal), generating varying degrees of stray light noise on the image tube background, deteriorating the image tube's equivalent background and causing its performance to deteriorate. Summary of the Invention

[0007] The purpose of the present invention is to eliminate discharge on the fluorescent screen of a tube and improve the background noise of the product, and to provide a conductive light-shielding film for the fluorescent screen substrate of a low-light-level image intensifier and a preparation method thereof. By forming a metal film on the stepped cylindrical surface of the optical fiber panel, which is the fluorescent screen substrate of the low-light-level image intensifier, the inter-electrode discharge of the fluorescent screen of the low-light-level image intensifier is effectively eliminated and the background noise is improved.

[0008] The technical solution adopted by the present invention to solve the actual problem is:

[0009] A layer of gold paste is coated on the stepped cylindrical surface of the non-conductive optical fiber panel. After high-temperature sintering, a high-conductivity, low-transmittance, and high-stability metal film layer is formed at the coating position, connecting it to the tube shell electrode, conducting away the negative charge (secondary electrons) accumulated on the fluorescent screen, and avoiding inter-electrode discharge on the fluorescent screen; at the same time, the metal film layer can effectively prevent external stray light from entering the image intensifier tube through the edge bevel of the panel and / or glass screen (glass material sealing), effectively eliminating the light feedback phenomenon caused by the luminescence of the phosphor, and significantly improving the background noise of the image intensifier. Specifically, the technical solution of the present invention is as follows:

[0010] A conductive light-shielding film for a low-light-level image intensifier screen substrate. The film is a thin film layer prepared on the stepped cylindrical surface of the low-light-level image intensifier screen substrate (fiber optic panel). The composition of the thin film layer is a gold:silver mass ratio of 9:1.

[0011] A method for preparing a conductive light-shielding film for a fluorescent screen substrate of a low-light-level image intensifier comprises the following steps:

[0012] (1) Prepare the gold paste organic liquid and place the optical fiber panel to be coated into the coating fixture;

[0013] (2) Start the rotating motor device to drive the optical fiber panel to be coated to rotate, and use a special brush to apply the gold paste organic liquid to the designated area of ​​the optical fiber panel to be coated;

[0014] (3) After coating is completed, remove the optical fiber panel;

[0015] (4) placing the optical fiber panel coated with the gold paste organic liquid into the panel sealing furnace and starting the high-temperature baking process for sintering;

[0016] (5) Cooling the panel sealing furnace and taking out the optical fiber panel;

[0017] (6) Check the appearance quality of the sintered film layer.

[0018] Furthermore, the designated area of ​​the optical fiber panel to be coated refers to the stepped cylindrical surface of the phosphor screen substrate (optical fiber panel) of the low-light-level image intensifier.

[0019] Furthermore, the mass ratio of gold to silver in the gold paste organic liquid is 9:1.

[0020] Furthermore, the high temperature baking procedure is: heating to a baking temperature of 400°C±10°C and keeping the temperature for more than 1 hour.

[0021] Furthermore, the cooling temperature of the cooling panel sealing furnace is lower than 50°C.

[0022] Beneficial effects of the present invention:

[0023] The present invention forms a metal film layer with high conductivity, low transmittance and high stability at the coating position by coating a layer of gold paste material on the stepped cylindrical surface of the non-conductive optical fiber panel and performing a high-temperature sintering process. The metal film layer is connected to the tube shell electrode, and the negative charge (secondary electrons) accumulated on the fluorescent screen is conducted away to avoid inter-electrode discharge on the fluorescent screen. At the same time, the metal film layer can effectively prevent external stray light from entering the image intensifier tube through the edge bevel of the panel and / or glass screen (the glass material sealing point), effectively eliminating the light feedback phenomenon caused by the luminescence of the phosphor, and significantly improving the background noise of the image intensifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : Conductive shading film;

[0025] Figure 2 :The process flow of thin film preparation;

[0026] Figure 3 : Gold paste coating position;

[0027] Figure 4 : Clamping and coating.

[0028] In the figure: 1- cathode window, 2- microchannel plate, 3- conductive light-shielding film, 4- phosphor screen substrate (fiber optic panel), 5- fiber optic panel, 6- coating position, 7- coating fixture. DETAILED DESCRIPTION

[0029] Reference Figure 2 、 Figure 3 and Figure 4 , the stepped cylindrical surface of the tube screen substrate is coated with sintered gold paste material to form Figure 1 The method for preparing the metal film with high conductivity, low transmittance and high stability is as follows: The method for preparing the metal film with high conductivity, low transmittance and high stability is as follows:

[0030] Shake the gold paste organic liquid material evenly: before coating, shake the gold paste bottle left and right to mix the gold paste organic liquid evenly, and pour an appropriate amount into a small open glass (or metal) container;

[0031] Install the coating fixture 7 corresponding to the optical fiber panel to be coated onto the rotating shaft of the rotating motor equipment, tighten the screws to fix the coating fixture 7, and use special tweezers to place the optical fiber panel 5 to be coated into the coating fixture 7;

[0032] Start the rotating motor device, turn on the switch, and adjust the speed to about 5rps;

[0033] Use a special brush to coat the designated gold paste coating position 6, that is, dip the special brush into the gold paste, gently press the brush head against and cover the step column surface, stay for about 5 seconds, remove the brush, and turn off the switch;

[0034] Stop the rotation, remove the optical fiber panel 5 with special tweezers and gently place it in a glass culture dish;

[0035] Put the culture dish containing the coated optical fiber panel 5 into the panel sealing furnace and close the furnace door;

[0036] Turn on the panel sealing furnace and set the high-temperature baking program until the baking temperature reaches 400°C. Keep it warm for about 1 hour, and let the panel sealing furnace cool down until the temperature is below 50°C.

[0037] Open the furnace door to quickly cool it to room temperature, and take out the fiber optic panel;

[0038] Check the appearance quality of the conductive light-shielding film 3. The film layer should be golden yellow with a metallic luster. No obvious through holes, gaps, or film warping or peeling should be allowed.

[0039] The present invention coats the stepped cylindrical surface of the image tube fluorescent screen substrate with sintered gold paste material to form a metal film with high conductivity, low transmittance and high stability, effectively eliminating the problem of fluorescent screen discharge in low-light-level image intensifiers and improving product background noise.

Claims

1. A method for preparing a conductive light-shielding film for a low-light-level image intensifier phosphor screen substrate, characterized in that: The following steps are involved: (1) Prepare the gold paste organic liquid and place the optical fiber panel to be coated into the coating fixture; (2) Start the rotating motor device to drive the optical fiber panel to be coated to rotate, and use a special brush to apply the gold paste organic liquid to the area where the low-light image intensifier phosphor screen substrate and the optical fiber panel step cylindrical surface of the optical fiber panel to be coated are connected; (3) After coating is completed, remove the optical fiber panel; (4) Place the optical fiber panel coated with the gold paste organic liquid into the panel sealing furnace and start the high-temperature baking process for sintering. The high-temperature baking process is as follows: heat up to a baking temperature of 400°C ± 10°C and keep warm for 1 hour; the gold film formed by sintering the gold paste organic liquid has a gold:silver mass ratio of 9:1; (5) Cool the panel sealing furnace and take out the optical fiber panel; (6) Check the appearance quality of the sintered film layer.

2. The method for preparing a conductive light-shielding film for a phosphor screen substrate of a low-light-level image intensifier according to claim 1, characterized in that: The cooling panel sealing furnace is cooled to a temperature below 50°C.

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