JPH03503221A - Noise shield for display devices - 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] Noise shield for display devices Background of the invention 1 tray standing upright The present invention provides electromagnetic interference (EMI)/radio frequency interference (RFI) shielding. It's about improvement. Noise emissions such as those mentioned above and sensitive receivers, etc. A shield is provided in front of the display terminal screen to prevent interference. Ru.

Measures from ′ in this The need for EMI/RF I shielding for display terminal screens is increasing. I am on the path to becoming a member. These screens are generally cathode ray tubes only. In some cases, it is a flat type panel device. The need for these filters is For several reasons. One of them is EMI and RFI emitted from display devices. There is a health issue for operators exposed to In addition, EM between devices The influence of I/RFI is also a problem. This problem is highly dependent on the source of the interference noise. This is particularly severe when a high-sensitivity image receiver is installed nearby. This particular example This may be the case if the cathode ray tube is located very close to a highly sensitive navigational image receptor. For example, a depth finder display, radar display, or other Display devices are often found on personal and commercial vessels and aircraft. LORAN (Long Range Navigation System, LORAN). Ru. LORAN signals are relatively weak and easily disturbed by EMI from CRTs. It will be done.

To solve this problem, a comparative interpretation method for various complex electrical signals has been proposed. There is. These methods require advanced technology and are expensive. Instead of this An alternative method is to physically mask the interfering noise at the source.

Shielding most of the surfaces of the equipment that emit interference By covering with a conductive shield such as a shield or metal box. shielding the surface of the display device itself, where securing the field of view is important. is even more difficult. Traditionally, wire mesh-based shields were used as display devices. proposed for surface use. These solutions generally work for black and white screens. is suitable, but in the case of a dot matrix type color display device, the white Yarmetsch significantly degrades the signal pattern to produce moiré patterns. be given This disturbance also results in a color shift.

Glass panel shields with transparent metal coatings have also been proposed.

These materials have a transparent substrate provided with a metal layer on the negative side. how many are they It has some disadvantages.

For one, it is extremely expensive and difficult to handle because it is glass. . Additionally, such panels are thick and heavy.

Representative for EMI/RFI shielding and use of shielding in safety environments Specific disclosures include: Bruce E., Kuhoian and Mar. c. A. Granted to Kemerling on October 25, 1983. National Patent No. 4.412.255; and the parent application of this application.

As is clear from the above explanation, high-performance E is suitable for use in display terminal devices. The need for MI/RFI shielding is well recognized. This need is new Not only for new equipment, but also for additions to existing units. . No such addition is found in known shields, and therefore it is necessary to supplement this. This is the object of this invention.

Summary of the invention This is an improved type of EMI/RFI filter for use on the front of the display terminal. It was invented here. These filters consist of a multilayer structure. Its multilayer structure makes it easy to see Fully glare-free, located closest to the user and farthest from the display surface. Equipped with a hard coating. The surface of this hard coating is transparent. It does not easily cause scratches and has a thickness of generally 3 to 10 microns. The next layer has a thickness of approx. 1 to about 50 mils plastic sheet. This plastic has a flat surface or a non-flat surface as necessary to fit along the surface of the display device. It is given a shape and molded by heat. The innermost layer itself is a dielectric and metal layer It is a laminate of. This layer has a dielectric-metal-dielectric shape or a dielectric One or more metal layers are sandwiched between them. The thickness of these layers is It is expressed as the electrical resistance value. (A thin layer has a high resistance value and a thick layer has a low resistance value.) vinegar). Using this numerical relationship, the metal layer has a resistance of 20 ohms or less. be done. These metal layers are electrically connected to a ground terminal.

This connection is usually made approximately at the outer periphery of the shield.

The shield is further characterized by optical transparency as well as the electrical conductivity mentioned above. in the visual field Typical transparency is 25% or more.

It should further be noted that the present invention facilitates consumer use of the above-described shields. We also provide kits for this purpose.

This kit has: (a) the size of the cathode ray tube display surface determined by the user; Transparent conductive film can be cut to the required size and processed according to the shape. and (b) pasted along the outer periphery of the sheet and then electrically Conductive tape that can be connected to the ground.

Detailed description of the invention 45 love respects The EMr/RFI filter of the present invention will be further detailed with reference to the accompanying drawings.

FIG. 1 is a partially cutaway sketch showing how the shield of the present invention can be used in a display terminal device. Shown as previously installed.

FIG. 2 is an enlarged cross-sectional view of the shield of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a method of laminating filter materials.

FIG. 4 shows one use of the invention step-by-step through six diagrams.

Awesome second The present invention combines high transparency and high conductivity to provide a high shielding effect. Provides MI/RFI shielding. This shield is located close to each other It is sufficiently effective in preventing mutual interference between the CRT and the high-sensitivity receiver. I can do that.

According to FIG. 1, a shield 10 of the present invention is shown in a position in front of a cathode ray tube 11. There is. The shield 10 is flat or molded to follow the surface of the vacuum tube 1. be done. This molding is usually a three-dimensional molding. Shield 10 is transparent inside central portion 12 and ground connector 13. Has 13a, 13b and 13c . These ground connectors preferably connect essentially transparent areas of shield 10. Fully surrounding (i.e. 360° grounded). In fact, the back area of the CRT and the remainder of the display unit/unit are also surrounded by a ground shield. simple For simplicity, these are not shown in FIG.

FIG. 2 shows a cross section of the shield of the invention. Shield 10 is at least all A hard coat 21 that does not cause glare on the surface, a transparent plastic substrate 22, and a conductive It has a metal-metal oxide layer 23 of a certain type. Further, in FIG. 2, the electrically conductive layer 23 and and is also electrically connected to a conductor 25 connected to the ground. Ground conductor 24 is shown; 24 and 25 are functionally similar to conductor 13 of FIG. is the same.

A full hard coat 21 is used to increase wear resistance. Usually this The layer is accessible to the operator of the display terminal when in use and is Others can touch it. Therefore, a full hard coat is required for operators. It has an important function of minimizing the possibility of damage caused by The hard coat 21 has For example, using hardened silica or acrylic based coatings I can do it. These types of hard coats are relatively matte. This is it The glare level due to light scattering on the outer surface of the shield is suppressed to 0.1 or less. I can get it. This also prevents fingerprints from forming if you touch the panel. . The thickness of the anti-reflective hard coat ranges from about 0.5 to about 20 mils, preferably In the range of about 1 to about 10 mils, preferably about 1.5 to about 8 mils. desirable. An example of a typical hard coat is Roll Coat, sold by MPV. Dyalex material or Ter Marno, a roll-coated product sold by t) Contains materials.

The shield IO has a flexible plastic substrate 22.

This substrate can be made of materials such as polycarbonate, polyester, polyether sulfone, etc. It is composed of a plasticized polymer. polycarbonate, polyester , polyethylene terephthalate (PET) for its chemical resistance and toughness. It is preferred as a substrate. The plastic substrate 22 is about 1 to about 50 mils. It has a thickness of If possible, it can be made even thicker. The thickness of the substrate is from approx. About 25 mils is preferred, and about 5 to about 20 mils is more preferred. The substrate 21 is , transparent, or dyed or pigmented. This is the shield It gives color to the light passing through it or helps sharpen the image on the screen.

For example, simple gray is often used to increase contrast, as well as green and orange. Orange is used to give a special color to the transmitted light. This coloring is done by plasti dyes or pigments can be incorporated into the coloring substrate itself, or colored layers can be added to the plastic. It is done by applying it on top of. The visibility required for the shield of the present invention is , the translucency of the plastic substrate usually exhibits a value between 30 and 100%. It will be realized when Generally, when the light transmittance is about 30% or less, the conductive metal layer Due to the additional loss of transmission due to This will deviate from the permissible range. The plastic matrix suppresses its translucency. Generally, the percentage is about 35% to about 95%, preferably about 40%. The range is approximately 80%. Light absorption into plastic substrates reduces translucency. by any of the known methods. Although not limited to this The methods include methods of incorporating pigments or dyes into the substrate 22; methods of incorporating pigments or dyes; There are methods to apply an overcoat, methods to impart circular polarization to the plastic layer, etc. be. In terms of ease of use, ease of handling and durability are important for controlling translucency. Generally preferred is the method of incorporating pigments into plastic substrates.

A transparent conductive layer 23 is provided on the inner surface of the substrate 22 . The details are shown in Figure 3. As can be seen, the layer 23 itself is composed of one or more layers. Figure 3 Smell 21 is the overall hard coat, 22 is the plastic substrate, and layer 23 is the dielectric layer. It has a body layer 31, a metal layer 32, and a dielectric layer 33. The shape of this conductor is metal It does not produce moiré pattern disturbances and has excellent optical It has definite advantages over traditional metal conductors due to its transparent nature. . The thickness of this multiple layer ranges from about 500 angstroms to about 2,000 angstroms. It is within the Roam range. The metal layer 32 is made of a conductive metal and has a thickness of about 50 angstroms. The range is approximately 500 angstroms from the trom.

The metals used include silver, gold, copper, nickel, and alloys thereof. The dielectric layer is It can be chosen independently of other layers and is typically about 100 angstroms thick. and 1.000 angstroms. Typical dielectric material is titanium dioxide , lead oxide, tin oxide, bismuth oxide, zircon oxide, iron oxide, isosium oxide, etc. and metal sulfides such as zinc sulfide. These dielectrics - gold The metal-dielectric sandwich structure is about 30% to about 80%, especially about 40% to about It is characterized by a translucency range of 80%.

An important property of a metal layer that is directly related to the performance of an EMI/RFI shield is its conductivity. It has high electrical conductivity. This layer should be 15 ohms per square or less, and If possible, it is desirable to have a conductivity of 12 ohm to 0.5 ohm per square. Yes.

The conductive layer 23 is further connected to a grounding conductor 24. This connection is made of conductive ink. This can be done using busbars, metal contacts, etc. Conductive adhesive tape can be used as a conductor This is preferable.

It can be seen from the figure that the conductor 24 is in contact with the dielectric layer 33. death However, it is often thought that good electrical connections are not possible with this method. why If so, this is because layer 33 is a dielectric. In fact, the concatenation method described here has the property of passing through the dielectric material, and the contact of 24 actually contacts the conductive layer 32. That is what you have done.

The conductive layer consists of a continuous layer. Such layers can be sputter deposited and vacuum deposited. Laminated by. According to the applicant's experience, S. 5chfleer, U, Hesfg and T by Geod joke h1n 5olfd F+) ms 54 (1978) 33; R, ni, Wa its, 12. J, L, Vossens and V/, Kern ( eds, ) by Th1n Fil Processes, Acad emic Press, New York, 197g, p.

131; J, A, Tboronton and A, S, Penfold , J., L. Vossen and W. Kern (eds, ). h1n Film Processes Academic Press.

New York, 1978; Andori, B. Fraser, 12. J. , L. Vossen and W. Kern (eds, ). lm Processes, Acadeo+jc Press.

The magnetron buttering described in New York, 1978, It is an excellent method for depositing layers in a precisely controlled manner.

The process for making the RFI/EMI shield of the present invention typically includes the following steps: Ru.

First, a hard coat is applied to one side of the plastic substrate. The hard coat is mainly This is done first for economic reasons.

Because it uses relatively low-cost materials, there is a risk that the product will be defective later. This is because other processes that use more expensive materials do not cause any damage. Second work In the step, a dielectric-metal-dielectric layer is applied. This is commercially used as a magnetron. This is done using a puttering machine, in which various layers are successively deposited in one pass. Either by using a standard electrode for each application, or by using a spattering device several times. A bus method is selected. In the case of the latter device, the plastic substrate is usually Supplied in rolls with a hard coating. Next, apply a hard coat and The roll material coated with a conductive layer is rewound to obtain the desired shield size. cut into sheets. The sheet is then heat-formed to conform to the shape of the display tube. be molded. If the display tube is an essentially flat panel, the shielding material should be Just trim it to the correct size. As in the case of conventional CRT units, the table If the surface of the tube is curved, the shield is heated using a conventional process. It can be molded. These are done using a mold press, but in this case the The operating temperature is about 110 to about 150°C for carbonate and about 150°C for polyester. from about 175°C to about 250°C. Other conventionally used methods There are vacuum forming and pressure forming methods, in which the plastic substrate is a layered material. By being drawn or pressurized into the mold with the material by pressure or vacuum. The molding is completed. These processes are carried out under exactly the same conditions as the mold press described above. be done.

The advantage of the shield of the present invention is that it is coated with a hard coat and a conductive layer. It can also be applied along the surface of the display without damaging or breaking these layers. The reason is that it can be molded to fit. As a result, processing costs are relatively reduced, and It is possible to reduce product costs.

The shield of this invention can be incorporated into equipment as an OEM component or later. It can be commercially available as a post-sale product for installation. Typical after sale For applications, the shield is used as shown in FIG. In Figure 4(a) The first step is shown. The user should hold the front cover in front of the CRT screen. Or remove the edge frame. The second step is shown in FIG. 4(b), and in this case, is the area of the display plus the area under the edge or cover, which is the length A. ) and width (B). In the third step, FIG. 4(c), the shield The material is cut to size according to the dimensions of (A) and (B).

The shield as supplied preferably has a peelable protective layer over the metal conductive layer. Delicious. This protective layer is peeled off in step 4 (FIG. 4(d)), and this In this case, it is important not to touch the exposed conductive layer directly with your fingers. In this case, the tree It is best to wear cotton gloves or hold only the edge F. It's a method. In the fifth step (Figure 4 (e)), the conductive adhesive tape is applied to the outer periphery of the shield. be pasted on. This can be done by cutting the tape to lengths A and B or by cutting the tape to lengths A and B. It is best to bend the tape at the corners. The conductive side of the tape is the conductive side of the film be contacted. The tape is firmly crimped onto the film for good adhesion.

In the sixth step (Figure 4(f)), the shield is attached to the front of the CRT display. The conductive side must face the display when installed. Outside the conductive tape The perimeter is connected to the chassis of the display device or other ground to ground. This is an additional This can be easily done by using additional conductive tape. After that, the edge flap The tray or cover plate is reinstalled.

The shield of the invention is further illustrated by the following example. This represents an embodiment of the invention. For illustrative purposes only, they should not be construed as limiting the scope of the invention. do not have.

Example 1 Based on the present invention, the EM I/RF I shield is fabricated as follows; Mass, polyester (polyethylene terephthalate) roll material is acrylic Coated on one side with a diffusive, non-glare hard coat made of The diameter is approximately 5 microns. The nominal thickness of the polyester is 15 mils. child The material is made using a magnetron evaporation system to form three layers of dielectric, metal, and dielectric. administered. Each of the dielectric layers has a thickness of approximately 300-500 angstroms. Two. The metal is primarily silver and the thickness is approximately 100 angstroms. 2 The two dielectric layers are similar to each other. This conductive laminate has approximately 10 It has a resistance value of ohms. The light transmittance of the conductive laminate is approximately 60%. plastic The black substrate is colored with a neutral gray pigment, giving it a translucency of 40 to 50%.

The overall level of transparency will be 25 to 30%.

The product molded as described above is taken out from the magnetron vapor deposition equipment, and a sheet is formed. cut to size. The sheet is then thermoformed, trimmed and stressed The molding process conforms to the surface of the cathode ray tube. Silver ink bus bar becomes conductive layer These then form a copper mesh that surrounds the outer circumference of the shield over 360°. Glued to the electrode. Alternatively, a conductive adhesive tape is applied to the outer edge of the conductive layer.

When the shield is visually inspected, it appears to exhibit a continuous metallic layer; this layer is transparent. It is clear. Shield because it doesn't have anything like Messico line The image that passes through is not obstructed.

When this shield is grounded via a conductor surrounding its outer periphery, the cathode ray tube Provides an effective EMI/RFI shield to prevent radio waves from being transmitted.

Example 2 The method of manufacturing the shield described in Example 1 is modified as follows. The shield is flat It is designed for use in front of a front panel display. Therefore, the seal The dome itself has a flat cross-section and no thermoforming as required in Example 1 takes place. .

Example 3 The manufacturing method of Example 2 is further modified as follows; colored neutral gray. Uncolored polyester is a popular alternative to polyester. For this purpose, the total Excellent sealing of the materials of Examples 1 and 2, even though the combined light transmission is approximately 60%. The code characteristics are maintained.

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Claims (1)

[Claims] Scope of patent claims; 1. Cathode ray tube display to prevent EMI/RFI radiation from the surface of the tube A transparent EMI/RFI shield used on the front of the device, Fully anti-glare hard cord outer layer and size and shape to match the display an intermediate plastic substrate provided with a shape; having a metal film layer and an intermediate dielectric layer, and covering the entire visible spectrum. Transparency of at least about 30% and electrical resistance of less than about 20 ohms per square and is connected to a conductive body that can be grounded on almost its entire circumference. an inner conductive layer; Transparent EMI/RFI shield with 2. The plastic substrate is coated with dye to give it 30 to 100% translucency. 2. The transparent EMI/RFI shield of claim 1, wherein a pigment is added. 3. The transparent EMI according to claim 1, wherein the resistance value is about 15 ohms or less per square. /RFI shield. 4. 2. The transparent EMI/RFI shield of claim 1 having a curved cross section. 5. 2. The transparent EMI/RFI shield of claim 1 having a flat cross section. 6. Claim 1, wherein the conductive layer sandwiches a metal layer between dielectric layers. Transparent EMI/RFI shield. 7. The metal layer has a conductive metal layer with a thickness of 50 to 500 angstroms. The transparent EMI/RFI shield according to claim 6. 8. 8. The transparent EMI/RFI shield of claim 7, wherein the metal comprises silver. 9. Transparent EMI/R according to claim 1, wherein the groundable electrical conductor is a conductive adhesive tape. FI shield. 10. Claims where the conductive layer includes multiple layers of metal tubing sandwiched and separated by dielectric layers Transparent EMI/RFI shield according to item 1. 11. 11. The transparent EMI/RFI shield of claim 10, wherein multiple refers to two. 12. 11. The transparent EMI/RFI shield of claim 10, wherein the number refers to three. 13. 12. The transparent EMI/RFI shield of claim 11, wherein the metal comprises silver. 14. 14. The transparent EMI/RFI seal of claim 13, wherein the dielectric comprises a metal oxide. Do. 15. two dielectrics/metals/ one located on each side of the plastic substrate The transparent EMI/RFI shield of claim 1 having a dielectric conductive layer. 15. The shield is used to prevent EMI/RFI noise radiation through the surface of the cathode tube. A kit for shielding electrode tubes after they are sold, (a) An outer layer of full-scale anti-glare hard cord and a an intermediate plastic substrate which is given a size and shape; having a metal film layer and an intermediate dielectric layer, and covering the entire visible spectrum. Transparency of at least about 30% and electrical resistance of less than about 20 ohms per square and is connected to a conductive body that can be grounded on almost its entire circumference. an inner conductive layer; one sheet-like transparent shielding material having (b) almost the outer periphery of the inner conductive layer; a conductive adhesive tape surrounding and capable of being conductively adhered to and grounded; A kit for shielding cathode tubes after sale. 17. Claim 1 further comprising a protective layer releasably adhered to the inner conductive layer. The kit described in 6. 18. Using the kit of claim 17, sealing a cathode ray tube of a video display device after sale. (b) exposing the outer periphery of the surface of the cathode ray tube; by trimming the sheet of metal material to match the outer circumference of the cathode ray tube surface. (c) conductive adhesive tape around the outer periphery of the trimmed sheet. (d) the trimmed sheet; When trimming, ground the conductive layer to the surface of the cathode ray tube, and place the conductive layer facing the cathode ray tube. ground the conductive adhesive tape that surrounds the sheet, and ground the outer periphery of the cathode ray tube surface. to cover again, How to include.