Background Art As well known to those skilled in the art, mother-of- pearl is a natural, hard, iridescent substance that forms the inner layer of certain mollusk shells, and has a beautiful, magnificent, brilliant pattern and color. From the past up to now, mother-of-pearl has thus been preferably, widely used as a high-grade ornamental material

for furniture or a variety of accessories, such as buttons, beads, etc. In order to inlay the surface of a thing, such as furniture, with mother-of-pearl to decorate the surface through a traditional process, a pattern cut along a desired design is primarily attached to the mother-of-pearl of a natural shell. Thereafter, the mother-of-pearl of the shell is manually and precisely cut along the attached pattern by an inlayer to form a plurality of desired mother-of-pearl pieces prior to inlaying the pieces at desired positions on the target surface one by one to form a desired entire pattern of mother-of-pearl on the target surface.

Such traditional process of inlaying the mother-of- pearl on the surface of a thing requires highly skilled, sophisticated inlayers and is excessively complex in its process, and necessarily uses highly expensive natural mother-of-pearl. In addition, it is necessary to cut the curved mother-of-pearl of natural shells to form desired mother-of-pearl pieces, and so the traditional process excessively consumes the expensive natural mother-of-pearl.

In an effort to overcome the above-mentioned problems experienced in the traditional process, another process of primarily forming a thin mother-of-pearl sheet by integrating a plurality of mother-of-pearl slices into a single flat sheet, and secondarily cutting the sheet to form desired ornamental pieces prior to inlaying the pieces on a target surface has been proposed.

In order to produce a thin mother-of-pearl sheet

having a desired effective area using the mother-of-pearl of natural shells, a natural shell is cut into a plurality of rectangular primary pieces, each having a width of 1 cm- 1.5 cm and a length of 5 cm cm, prior to slicing each primary piece into a plurality of thin mother-of-pearl slices using a slicing machine. Thereafter, the thin mother-of-pearl slices are attached to the bonding surface of an adhesive tape such that the edges of the slices are overlapped together, thus forming a mother-of-pearl slice assembly having a width of 20 cm cm and a length of 15 cm cm. The mother-of-pearl slice assembly is, thereafter, coated with a mixture of 2: 1 or 4: 1 of epoxy resin and polyamide resin, on its pattern surface. A plurality of mother-of-pearl slice assemblies coated with the mixture are laminated together to form a laminated structure with release sheets interposed between the assemblies. In such a case, the maximum number of slice assemblies preferably laminated in one laminated structure may be set to 500. The laminated structure is, thereafter, continuously compressed by a compression press machine under pressure of 1.5 ton, at a temperature of 70- 80°C and for 2 -3 hours, with upper and lower compression plates of the press machine provided with heating wires. After the laminating and compressing process, the release sheets are removed from the junctions of the mother-of-pearl slice assemblies to separate the compressed slice assemblies from each other and form thin mother-of-pearl sheets. Each of

the thin mother-of-pearl sheets is, thereafter, ground on its opposite surfaces once, twice or three times using a grinder, such as a diamond grinding wheel, to finally form a smooth, flat, thin mother-of-pearl sheet.

Korean Patent Publication No. 92-8871 allowed to Jong- soo Kim discloses another process of manufacturing smooth, thin mother-of-pearl sheets. This process comprises a slicing step, a sheet forming step, a coating step, a compressing step, a primary heating step, a primary cooling step, a secondary heating and cooling step, and a surface finishing step. At the slicing step, waste mother-of-pearl, obtained from a traditional mother-of-pearl cutting process, are sliced to form thin mother-of-pearl slices. At the sheet forming step, the mother-of-pearl slices are attached to a paper such that the edges of the slices are overlapped together to form a mother-of-pearl sheet having a desired area. The mother-of-pearl sheet is, thereafter, coated with a transparent epoxy resin layer at the coating step prior to hardening the epoxy resin layer. At the compressing step, 20 sheets coated with the epoxy resin layer are primarily laminated together to form a laminated structure.

The laminated structure is, thereafter, continuously compressed by a compression press machine under pressure of 150 ton for about 5 minutes. The laminated structure from the compressing step is heated within a hermetically sealed heating cabinet at a temperature of about 120°C and for about 90 minutes at the heating step. The heated structure

is, thereafter, naturally cooled for about 3 hours. The heating and cooling steps are performed twice. Thereafter, the surface finishing step is performed to remove impurities, such as resin bonded to the opposite surfaces of the mother-of-pearl sheets, from the surfaces through a grinding process using a diamond grinding wheel, thus producing desired smooth, flat mother-of-pearl sheets having a large area suitable for forming an ornamental pattern having a desired size.

The above-mentioned processes have an advantage in that they produce smooth, flat mother-of-pearl sheets having a large area suitable for easily forming desired patterns, thus improving work efficiency while forming the desired patterns. However, the mother-of-pearl sheets produced through the processes are problematic in that they are excessively thin with a thickness of 0.2 mm 5 mm, and so they are inferior in their structural strength and are fragile and brittle. The mother-of-pearl sheets produced through the above-mentioned processes are thus easily cracked along fissures and ridges during a treatment and are too thin, so that they are not preferable to be inlaid on the surface of a thing, such as furniture. Since the thin mother-of-pearl sheets are not effectively usable as an individual sheet during an inlaying process due to the above-mentioned structural fault, it is necessary to form a mother-of-pearl panel having a desired thickness by laminating a predetermined number of thin mother-of-pearl

sheets, for example, 3-10 sheets, together prior to cutting the mother-of-pearl panel into desired patterns prior to an inlaying process. Such a mother-of-pearl panel has a flat and smooth surface similar to that of paper and a desired thickness, in addition to an area sufficiently larger than the mother-of-pearl sheet of a natural shell, and so the mother-of-pearl panels highly improve work efficiency while designing patterns of mother-of-pearl and cutting the patterns from the panels, in comparison with the case of designing and cutting patterns using the thin natural mother-of-pearl sheets. In addition, an inlayer is able to simply and easily cut a fine, complex pattern as an integrated pattern from such a mother-of-pearl panel through a single cutting step, and so it is possible to reduce the amount of waste of expensive mother-of-pearl during an inlaying process.

Even though such mother-of-pearl panels produced through the above-mentioned processes desirably improve work efficiency while designing patterns of mother-of-pearl and cutting the patterns from the panels as described above, the processes are problematic in that it is necessary to use a great number of mother-of-pearl slices from natural shells to produce one desired mother-of-pearl panel. In order to produce a mother-of-pearl panel having desired area and thickness, a plurality of mother-of-pearl sheets are primarily produced through a complex process, and are laminated together to form a desired panel. Due to the

consumption of such a great number of expensive mother-of- pearl slices and the complex production process, the final products of the processes, or the mother-of-pearl panels, are very expensive, excessively increasing the production cost of a thing inlaid with patterns of mother-of-pearl. In the prior art, desired patterns may be automatically and precisely cut from such a mother-of-pearl panel through a laser cutting process. However, such a laser cutting process may undesirably burn the cut edges of the patterns since the mother-of-pearl consists of calcium, thus discoloring the cut edges of the mother-of-pearl patterns and making ash at the cut edges. Therefore, it is very difficult to obtain a fine pattern of mother-of-pearl having desired quality during a laser cutting process. This forces an inlayer to manually cut desired patterns from the mother- of-pearl panel using a conventional cutting machine.

However, such a manual cutting of the mother-of-pearl patterns using a conventional cutting machine reduces work efficiency while cutting the patterns, increases the cutting time, and does not allow an inlayer to finely or precisely cut the mother-of-pearl patterns. Therefore, it is very difficult for inlayers to cut complex and fine patterns from the mother-of-pearl panels through such a manual cutting process.

As described above, mother-of-pearl is a natural, hard, iridescent substance having a beautiful, magnificent, brilliant pattern and color, and so mother-of-pearl has been

preferably, widely used as a high-grade ornamental material for furniture, music instruments, or a variety of accessories from the past up to now. For example, mother- of-pearl is preferably used as functional markers, ornamental patterns, or decorative symbols inlaid on the surfaces of the fingerboards and/or the hollow bodies of high-grade stringed instruments. Such functional markers, ornamental patterns, or decorative symbols formed on the surfaces of high-grade stringed instruments are desired to be made of a high-grade ornamental material capable of increasing the value of such instruments. Mother-of-pearl sufficiently meets the above-mentioned requirement for high- grade ornamental material usable as the material of functional markers, ornamental patterns, or decorative symbols inlaid on the surfaces of the fingerboards and/or the hollow bodies of high-grade stringed instruments.

When desired patterns, such as butterflies, bees, roses and/or other symbols made by cutting mother-of-pearl panels produced by laminating a plurality of mother-of-pearl sheets together as described above, are used as, for example, position markers formed on the top surface of the fingerboard of a stringed instrument, such as a guitar, through an inlaying process, the patterns are primarily implanted on the flat rough top surface of the fingerboard before the top surface of the fingerboard with the patterns is subjected to a surface finishing process, in which the surface is ground or cut to form a smooth flat surface or a

smooth rounded surface having a desired radius of curvature.

During such a surface finishing process, the mother-of-pearl patterns inlaid on the top surface are ground or cut to be sanded at their upper surfaces. This means that the mother- of-pearl patterns, primarily inlaid as position markers on the fingerboard of a stringed instrument before a surface finishing process, must have a sufficient thickness, including the portion to be sanded during the surface finishing process. This forces the mother-of-pearl panels for the patterns to have a substantial thickness capable of meeting the desired requirements.

However, in order to produce the thin mother-of-pearl sheets, each having a thickness of 0.2 mm 5 mm, through the above-mentioned processes, it is necessary to overlap several ten mother-of-pearl slices of natural shells together and perform a complex treatment steps, thus excessively increasing the production cost of such sheets.

Furthermore, in order to produce a desired mother-of-pearl panel having a desired thickness, it is necessary to laminate a predetermined number of expensive mother-of-pearl sheets, for example, 5-10 sheets, together. Therefore, such a mother-of-pearl panel becomes excessively expensive.

It is thus necessary to provide a mother-of-pearl plate, which is made of one thin mother-of-pearl sheet without laminating several mother-of-pearl sheets together, different from the above-mentioned mother-of-pearl panels, and which has a sufficient thickness including the portion

to be sanded during a surface finishing process for a target surface after a mother-of-pearl pattern inlaying step, and which has improved structural strength, improved resistance to cranking, and improved flexibility, thus being improved in work efficiency while designing patterns and cutting the patterns from the mother-of-pearl plate, and which is less likely to be thermally damaged at its cut edges during a laser cutting process, thus allowing an inlayer to easily form desired patterns of mother-of-pearl having fine, clean and precise edges through such a laser cutting process.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and the primary object of the present invention is to provide a mother-of-pearl ornamental plate, which effectively provides a desired pattern of mother-of-pearl using one thin mother-of-pearl sheet, thus remarkably reducing the production cost of such patterns.

Another object of the present invention is to provide a mother-of-pearl ornamental plate, which is less likely to be thermally damaged at its cut edges during a laser cutting process, thus allowing an inlayer to easily form desired patterns of mother-of-pearl having fine, clean and precise edges, different from the conventional cases of laser- cutting desired patterns from natural shells having mother-

of-pearl layers or laser-cutting desired patterns from mother-of-pearl panels made by laminating a plurality of thin mother-of-pearl sheets together.

A further object of the present invention is to provide a mother-of-pearl ornamental plate, which is preferably usable as the material of patterned position markers inlaid on the fingerboard of a stringed instrument, such as a guitar, and is less likely to crack during a fret implanting process or another process of adjusting the radius of curvature of the entire frets after the fret implanting process.

Still another object of the present invention is to provide a mother-of-pearl ornamental plate, which is highly flexible to allow a mother-of-pearl strip, made by cutting the plate, to be easily bent without being broken even when the strip is somewhat excessively bent to have a desired radius of curvature.

Still another object of the present invention is to provide a mother-of-pearl ornamental plate, which is fabricated using one thin mother-of-pearl sheet without laminating several mother-of-pearl sheets together, and has a desired thickness including the portion to be sanded during a surface finishing process of grinding or cutting a target surface inlaid with patterns made by cutting the mother-of-pearl plate.

Still another object of the present invention is to provide a stringed instrument having or inlaid with

functional or decorative patterns, made of the above- mentioned mother-of-pearl plate through a cutting process.

In order to accomplish the above objects, the present invention provides a mother-of-pearl ornamental plate. This mother-of-pearl ornamental plate has a double-or triple- layered structure with a sufficient thickness, and consists of a conventionally produced thin mother-of-pearl sheet having a thickness of about 0.2 mm 5 mm, with a transparent synthetic resin layer formed on at least one surface of the sheet by coating transparent liquid epoxy, transparent liquid acryl, or transparent liquid Formica on the surface to a predetermined thickness, or laminating a transparent epoxy film, a transparent acryl film, or a transparent Formica film, having a predetermined thickness, on the surface. The mother-of-pearl ornamental plate of the present invention has the same high-grade pattern as expected from natural mother-of-pearl, and has a desired thickness (about 0.5 mm mm) including the portion to be sanded during a surface finishing process of cutting or grinding a target surface inlaid with patterns made by cutting the ornamental plate. The mother-of-pearl plate of this invention also has improved structural strength, improved resistance to cracking, and improved flexibility, thus being improved in work efficiency while designing patterns and cutting the patterns from the mother-of-pearl plate. This plate is also less likely to be thermally damaged at its cut edges during a laser cutting process,

thus allowing an inlayer to easily form desired patterns of mother-of-pearl having fine, clean and precise edges through such a laser cutting process. The present invention also provides a stringed instrument having or inlaid with patterns made of the ornamental plate, used as the pickguard, the sound hole inlay, the bridge and/or the position markers of the fingerboard.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a flowchart of a process of manufacturing a thin mother-of-pearl sheet used in the ornamental plate of the present invention; Fig. 2 is a sectional view of an ornamental plate made of a thin mother-of-pearl sheet and coated or laminated with transparent synthetic resin layers or films on its opposite surfaces in accordance with an embodiment of the present invention; Fig. 3 is a sectional view of the fingerboard of a guitar inlaid with a cut piece of the ornamental plate of this invention on its top surface before a surface finishing process; Figs. 4a and 4b are sectional views of the fingerboard

of Fig. 3, in which: Fig. 4a shows a surface finishing process of grinding the top surface of the fingerboard with the cut ornamental piece to form a rounded top surface having a predetermined radius of curvature, and Fig. 4b shows the cross-section of the fingerboard after the surface finishing process; Fig. 5 is a perspective view of a part of the fingerboard of a guitar inlaid with an art pattern, or a rose pattern, made of the ornamental plates of this invention, on its top surface before a fret implanting process; and Fig. 6 is a front view of a guitar having or inlaid with a variety of patterns, made of the ornamental plates of this invention, and used as the inlay of the sound hole, the pickguard, the bridge and the position markers on the top surface of the fingerboard.

Best Mode for Carrying Out the Invention Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

Fig. 1 is a flowchart of a process of manufacturing a thin mother-of-pearl sheet 10a used in the ornamental plate 10 of the present invention. As shown in the drawing, it is necessary to primarily produce a thin mother-of-pearl sheet

10a in order to manufacture a desired mother-of-pearl ornamental plate 10 of this invention. The process of producing the thin mother-of-pearl sheet of this invention remains the same as that described for the prior art as follows.

First process of manufacturing a thin mother-of-pearl sheet In order to produce a thin mother-of-pearl sheet 10a using natural shells having mother-of-pearl layers, each natural shell is primarily cut using a cutter, such as diamond cutting wheel, into a plurality of rectangular primary pieces, each having a width of 1 cm ~ 1. 5 cm and a length of 5 cm cm, at a shell cutting step. Each primary piece from the shell cutting step is, thereafter, sliced into a plurality of thin mother-of-pearl slices using a slicing machine at a slicing step. Thereafter, a slice assembly forming step is performed. At the slice assembly forming step, the thin mother-of-pearl slices are attached to the bonding surface of an adhesive tape such that the edges of the slices are overlapped together, thus forming a mother-of-pearl slice assembly having a width of 20 cm-30 cm and a length of 15 cm-25 cm. The mother-of-pearl slice assembly is, thereafter, coated with a mixture of 2: 1 or 4: 1 of epoxy resin and polyamide resin, on its pattern surface at a resin coating step. A laminating and compressing step is performed after the resin coating step. At the

laminating and compressing step, a plurality of mother-of- pearl slice assemblies coated with the mixture are laminated together to form a laminated structure with release sheets interposed between the slice assemblies. In such a case, the maximum number of slice assemblies preferably laminated in one laminated structure may be set to 500. The laminated structure is continuously compressed by a compression press machine under pressure of 1.5 ton, at a temperature of 70- 80°C and for 2-3 hours, with upper and lower compression plates of the press machine provided with heating wires.

After the laminating and compressing step, the release sheets are removed from the junctions of the mother-of-pearl slice assemblies to separate the compressed slice assemblies from each other and form thin mother-of-pearl sheets. Each of the thin mother-of-pearl sheets is, thereafter, ground on its opposite surfaces once, twice or three times using a grinder, such as a diamond grinding wheel, at a surface grinding step to finally form a smooth, flat, thin mother- of-pearl sheet lOa having a thickness of about 0.2 mm 5 mm.

Second process of coating or laminating synthetic resin layers or films In order to produce a mother-of-pearl ornamental plate 10 of this invention, a process of coating or laminating a synthetic resin layer 10b on at least one surface of the thin mother-of-pearl sheet 10a is performed. This coating

or laminating process is the important process of the present invention. In the coating or laminating process, a synthetic resin layer 10b is formed on at least one surface of the mother-of-pearl sheet 10a manufactured at the above- mentioned first process. In order to form the synthetic resin layer 10b on the sheet 10a, transparent liquid epoxy, transparent liquid acryl, or transparent liquid Formica may be coated on at least one surface of the sheet 10a to a thickness of 0.1 mm 3 mm through a roller coating process or a spray coating process. Alternatively, the synthetic resin layer 10b may be formed on the thin mother- of-pearl sheet 10a by laminating a transparent epoxy film, a transparent acryl film, or a transparent Formica film, each having a thickness of 0.1 mm 3 mm, on at least one surface of the sheet 10a. Therefore, a desired mother-of- pearl ornamental plate 10, having a double-or triple- layered structure with the thin mother-of-pearl sheet lOa and an entire thickness of 0.5 mm mm, is produced. In a brief description, the mother-of-pearl ornamental plate 10 of this invention is produced by coating or laminating a synthetic resin layer or film having a predetermined thickness on at least one surface of a thin mother-of-pearl sheet 10a having a thickness of about 0.2 mm 5 mm. The mother-of-pearl ornamental plate 10 of this invention has improved structural strength, improved resistance to cracking, and improved flexibility, thus being improved in work efficiency while designing patterns and cutting the

patterns from the mother-of-pearl plate. This plate 10 also has a sufficient thickness including the portion to be sanded during a surface finishing process for a target surface after a mother-of-pearl pattern inlaying step. Such a mother-of-pearl ornamental plate 10 or a process of manufacturing such plates 10 is not disclosed in or easily induced from the prior technique relating to the art, but is newly proposed by the inventor of this invention.

Fig. 2 is a sectional view of the ornamental plate 10, made of a thin mother-of-pearl sheet 10a and coated or laminated with transparent synthetic resin layers or films 10b on its opposite surfaces in accordance with an embodiment of the present invention.

Position markers are typically arranged on the fingerboard of a stringed instrument, such as a guitar, at positions between frets, and allow a person to easily set chords and tones while playing the stringed instrument.

Such a position marker typically consists of a cylindrical piece, which is made of a plastic material and has a diameter of about 3 mm mm, and is implanted on the wood fingerboard at a desired position to a predetermined depth such that the top surfaces of the position markers are level with the top surface of the fingerboard. Such position markers of stringed instruments have been typically recognized as functional markers rather than decorative items. However, when position markers, defined by beautiful patterns made of a high-grade ornamental material, are

inlaid on the fingerboard while keeping their original functions as position markers, it is possible to decorate the top surface of the fingerboard and increase the value of a stringed instrument.

In order to give such a decorative function of the position makers in addition to the original function of the markers, desired patterns made of the mother-of-pearl ornamental plate 10, such as a variety of flowers, butterflies, bees, spiders and other symbols, designs, and logos expressing the manufacturer of the stringed instrument, may be inlaid on the fingerboard of a stringed instrument so as to be used as position markers.

Alternatively, an art pattern, for example, a rose pattern, made of the mother-of-pearl ornamental plate 10 and having a stem, leaves and several flowers of different sizes, may be inlaid on the fingerboard of a stringed instrument, in addition to inlaying differently colored flowers, bees, butterflies, or spiders made of the mother-of-pearl ornamental plate 10 at desired positions between the rose pattern so as to be used as position markers. As a further alternative, a variety of geometrical figure patterns, such as differently sized circles, ovals, or rectangles made of the mother-of-pearl ornamental plate 10, may be inlaid on the fingerboard at desired positions so as to be used as position markers. When position markers, defined by beautiful patterns made of the mother-of-pearl ornamental plate 10 of this invention, are inlaid on the fingerboard of

a stringed instrument as described above, it is possible to decorate the fingerboard and increase the value of the stringed instrument.

The mother-of-pearl ornamental plate 10 of Fig. 2 is a triple-layered structure having a sufficient thickness, and consists of a thin mother-of-pearl sheet 10a having a thickness of about 0.2 mm 5 mm, with a synthetic resin layer lOb having a predetermined thickness and formed on each of opposite surfaces of the sheet 10a through a resin coating process or a resin film laminating process. When a pattern, formed by cutting the mother-of-pearl ornamental plate 10 of Fig. 2, is implanted on the top surface of a fingerboard 20 as shown in Fig. 3, only the upper synthetic resin layer 10b coated or laminated on the upper surface of the sheet lOa is sanded from the pattern during a surface finishing process of cutting or grinding the fingerboard 20 with the pattern to form a desired radius"r"of curvature of the fingerboard 20 as shown in Figs. 4a and 4b, without sanding the thin mother-of-pearl sheet 10a. Therefore, it is possible for the mother-of-pearl plate 10 of this invention to remarkably reduce the cost of mother-of-pearl during such a pattern inlaying process without deteriorating the quality of inlaid patterns in comparison with a conventional technique of cutting desired mother-of-pearl patterns from natural shells or from mother-of-pearl panels each made by laminating a plurality of thin mother-of-pearl sheets together.

Since the mother-of-pearl ornamental plate 10 of this invention comprises a thin mother-of-pearl sheet 10a having a thickness of about 0.2 mm 5 mm, with a synthetic resin layer lOb having a predetermined thickness and formed on each surface of the sheet 10a through a resin coating process or a resin film laminating process so as to protect the sheet 10a as described above, the plate 10 is less likely to be burnt, discolored, or form ash at the cut edges of the thin mother-of-pearl sheet 10a during a laser cutting process of cutting desired patterns from the plate 10. In a brief description, the mother-of-pearl plate 10 of this invention is less likely to be thermally damaged during a laser cutting process. In addition, the synthetic resin layers 10b of the plate 10 are cleanly cut through the laser cutting process, and so it is possible to more precisely, cleanly and quickly cut desired patterns from the mother-of- pearl plate 10 through such a laser cutting process regardless of profiles of the patterns, different from a conventional process of cutting mother-of-pearl patterns from natural shells through a laser or mechanical cutting process, or cutting patterns from a mother-of-pearl panel made by laminating a plurality of thin mother-of-pearl sheets together.

The mother-of-pearl plate 10 of this invention is made by coating or laminating an elastic, flexible synthetic resin layer or film on at least one surface of a thin, brittle mother-of-pearl sheet having a low structural

strength. Therefore, when a fret implanting process is performed to set a plurality of frets 30 on the fingerboard of a stringed instrument after an art pattern, such as a rose pattern made by cutting the mother-of-pearl plate 10 of this invention, is inlaid on the fingerboard, the art pattern inlaid on the fingerboard is less likely to be damaged, deformed or broken irrespective of external force applied to the pattern from the frets. That is, even though the frets 30 are implanted on the fingerboard 20 across the art pattern, for example, the stem of a rose pattern, inlaid on the fingerboard as shown in Fig. 5, or are forcibly adjusted in their radiuses of curvature or their heights by an external impact after a fret implanting process, any impact applied to the pattern is effectively absorbed by the elastic and flexible synthetic resin layers lOb without causing any cracks on the thin mother-of-pearl sheet 10a.

In addition, since the mother-of-pearl plate 10 of this invention is highly flexible due to the synthetic resin layers lOb, it is possible for a mother-of-pearl strip, made by longitudinally cutting the plate 10, to be easily bent without being cracked or broken even when the strip is somewhat excessively bent to have a desired radius of curvature. Therefore, the mother-of-pearl plate 10 of this invention may be preferably usable as an ornamental pattern of the sound hole inlay 40, which is formed by inlaying the pattern along the edge of the excessively curved sound hole of the hollow body of a stringed instrument as shown in Fig.

6, in addition to the use as the position markers inlaid on the fingerboard.

Some stringed instruments, for example, guitars have a guard-functional accessory, so-called a pickguard 50, which is attached to the surface of the hollow body at a position around the sound hole and has a decorative function, in addition to its original function of protecting the smooth surface of the hollow body from finger nails or a plectrum when a person plucks the strings with fingers or the plectrum. Such a pickguard 50 has a large area and a thickness of about 0.5 mm ~ 2 mm, and has been typically made of a plastic plate. Since the pickguards are different in their materials, colors, and shapes from those of the hollow bodies of stringed instruments, and may be somewhat freely changed in their shapes as desired, it is possible to increase the value of the stringed instruments by changing the materials, colors, shapes and patterns of such pickguards. In the same manner as that described for the pickguards 50, it is also possible to increase the value of stringed instruments by changing the materials, colors and patterns of bridges 60, which are provided on the hollow bodies of the stringed instruments for holding the ends of strings on the bodies. The mother-of-pearl plate 10 of this invention is preferably and effectively used as the material of such pickguards and bridges of stringed instruments. In such a case, the pickguard and bridge may be entirely made of a mother-of-pearl plate 10 of this invention, or may be

inlaid with desired patterns made by cutting the plate 10.

When a pickguard or a bridge, entirely made of the mother- of-pearl plate 10 of this invention, is used with a stringed instrument, it is possible to remarkably reduce the cost of the pickguard or the bridge in comparison with using natural shells or conventional mother-of-pearl panels each made by laminating a plurality of thin mother-of-pearl sheets together since the area of the pickguard or the bridge is remarkably larger than that of position makers. When a pickguard or a bridge, inlaid with desired patterns made by cutting the plate 10, is used with a stringed instrument, the mother-of-pearl patterns are inlaid on the pickguard or the bridge made of a plastic material. Of course, it should be understood that the sound hole inlay 40 may be entirely made of a mother-of-pearl plate 10 of this invention, or may be inlaid with desired patterns made by cutting the plate 10.

In the preferred embodiment, the mother-of-pearl plate 10 of this invention is used as the material of ornamental patterns for guitars, a kind of stringed instrument.

However, it should be understood that the mother-of-pearl plate 10 of this invention may be preferably usable as the material of ornamental patterns for another type of stringed instrument, decorative patterns for surfaces of furniture, and basic patterns for a variety of signboards.

In the preferred embodiment, the mother-of-pearl plate 10 of this invention has a triple-layered structure with a

thin mother-of-pearl sheet coated or laminated with two transparent synthetic resin layers or films on opposite surfaces of the thin mother-of-pearl sheet. However, it should be understood that the mother-of-pearl plate of this invention may have a double-layered structure, with a thin mother-of-pearl sheet coated or laminated with one transparent synthetic resin layer or film on either surface of the thin mother-of-pearl sheet, without affecting the functioning of this invention. It should be also understood that the mother-of-pearl plate of this invention may have a triple-layered structure, with a thin mother-of-pearl sheet coated or laminated with one opaque synthetic resin layer or film on one surface of the thin mother-of-pearl sheet and one transparent synthetic resin layer or film on the other surface of the sheet, without affecting the functioning of this invention. In the case of the triple-layered mother- of-pearl plate with one opaque synthetic resin layer or film and one transparent synthetic resin layer or film, it is possible to reflect light beams at the opaque synthetic resin layer or film, and make the mother-of-pearl pattern of the sheet become more iridescent.

Industrial Applicability As described above, the present invention provides a mother-of-pearl ornamental plate, which is made of one thin mother-of-pearl sheet without laminating several mother-of-

pearl sheets together. That is, the mother-of-pearl plate of this invention is easily and simply produced by coating or laminating a transparent synthetic resin layer or film on at least one surface of the thin mother-of-pearl sheet. The mother-of-pearl plate is thus improved in its work efficiency while designing or cutting mother-of-pearl patterns from the plate, in addition to an improvement in its physical and chemical properties. The mother-of-pearl plate of this invention also has a sufficient thickness including the portion to be sanded during a surface finishing process of cutting or grinding a target surface after a mother-of-pearl pattern inlaying step, and so the patterns made of the mother-of-pearl plate are less likely to be damaged to the thin mother-of-pearl sheet regardless of such a surface finishing process. Therefore, the mother- of-pearl plate remarkably reduces the cost of mother-of- pearl patterns in comparison with the conventional cases of cutting desired patterns from natural shells having mother- of-pearl layers or cutting desired patterns from mother-of- pearl panels made by laminating a plurality of thin mother- of-pearl sheets together.

In addition, the mother-of-pearl plate of this invention is cleanly cut through a laser cutting process due to the presence of the synthetic resin layer or film, and so it is possible to more precisely, cleanly and quickly cut desired patterns from the mother-of-pearl plate through such an automatic laser cutting process in a commercial quantity

regardless of profiles of patterns, different from a conventional process of mechanically cutting mother-of-pearl patterns from natural shells, or mechanically cutting patterns from a mother-of-pearl panel made by laminating a plurality of thin mother-of-pearl sheets together.

Furthermore, when the mother-of-pearl plate of this invention is preferably usable as the material of patterned position markers inlaid on the fingerboard of a stringed instrument, such as a guitar, and is less likely to crack during a fret implanting process or another process of adjusting the radius of curvature of the entire frets after the fret implanting process. This reduces the proportion of defective stringed instruments inlaid with mother-of-pearl patterns used as position markers on the fingerboards. This mother-of-pearl plate is also highly elastic and flexible to allow a mother-of-pearl strip, made by cutting the plate, to be easily bent without being cracked or broken even when the strip is somewhat excessively bent to have a desired radius of curvature. Therefore, the mother-of-pearl plate is preferably usable as the material of continuously and variously curved ornamental patterns having substantial lengths.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.