WO2010004581A2

WO2010004581A2 - Laserscript on leaves

Info

Publication number: WO2010004581A2
Application number: PCT/IN2009/000386
Authority: WO
Inventors: Venkata Reddy Guntakanti
Original assignee: Venkata Reddy Guntakanti
Priority date: 2008-07-08
Filing date: 2009-07-08
Publication date: 2010-01-14
Also published as: WO2010004581A3

Abstract

Described herein is a method and processing technique of palm leaves and bamboo stem slices for preserving them for longer duration and a method of engraving/printing on palm leaves comprising the step of printing/engraving seasoned palm leaves using laser or stylus, removing the excess ink, followed by drying after the applications of a preservative. The present invention can be incorporated into the production of consumable products like palm leaves manuscripts, visiting cards on palm leaves or bamboo slices, wedding and all other types of invitations. It can also be used to engrave artistic designs on the said material. The life time of printed-paper is very limited whereas the palm leaves containing engraved manuscripts have been found to be ever living i.e. thousands of years it can be as it is.

Description

LASERSCRIPT ON LEAVES

FIELD OF THE INVENTION

This invention relates to a method and processing technique of palm leaves and bamboo stem slices for preserving it for longer duration and engraving/printing on palm leaf or bamboo stem slices using laser engraving or laser markings and screen printing.

BACKGROUND OF THE INVENTION

Laser is widely used in a number of applications such as cutting and peening of metals, welding, printing, engraving, holography, and medical instruments. Particularly laser engraving is used for engraving on wood, metallic surfaces, stones, glasses, jewellery, and fine art material.

Screen printing is a printing technique that creates a sharp-edged image using a stencil. Screen printing is more versatile than traditional printing techniques. The surface does not have to be printed under pressure, unlike etching or lithography, and it does not have to be planar. Screen printing inks can be used to work with a variety of materials, such as textiles, ceramics, wood, paper, glass, metal, and plastic.

Information about palm leaf manuscripts can be found in the URL given under no. 1 of the references. More information on the type, properties and writing of palm leaves can be found in the URL given under no. 2 of the references.

The earlier methods of writing over palm leaves were as follows:

1. These were written either by stylus or sharp nail. The disadvantage of this is legibility, lack of opportunity to highlight special features- and also it suffered from variations in the handwriting of one person to another. 2. Copying manuscript was equally tough, time consuming and with high probability of one committing mistakes, there by at times affecting contents, or meaning.

3. It also suffered from restrictions of depicting figures, graphics for better understanding.

DISCUSSTION OF PRIOR ART

Indian Patent application no. 967/DEL/2006 describes a Magic plant wherein the invention relates to laser — engraving on the seed, and beam will come outside with the message engraved on it.

TW 404871 (B) discloses a device and method for machining transparent medium by laser wherein the laser beam is focusing onto the support through the transparent medium to cut or scribe characters of figure in a transparent medium.

CN1760047 (A) describe and claims method for carving leaves through laser wherein the laser carving method includes steps of selecting a undried and undamaged leaf of areas not less than 30 sq.cm is dried in air, choosing a design pattern, inputting it to computer and placing the leaf on the carving platform for carving.

WO/2007/130968 discloses Method and apparatus for non-invasive laser based labeling of plant products provides a method and apparatus for labeling plant products based on laser activation of a color changing compound placed on at least a part of the surface of the plant products. The plant product may be any suitable fruit, including non- citrus and citrus fruit, vegetable, legume etc.

There has been no mention of laser engraving on palm leaves, which are storable for a hundreds of years. LASER ENGRAVING:

Laser engraving is the practice of using lasers to engrave or mark an object. (Ref. No. 3) The technique can be very technical and complex, and often a computer system is used to drive the movements of the laser head. Despite this complexity, very precise and clean engravings can be achieved at a high rate. The technique does not involve tool bits, which contact the engraving surface and wear out and will not damage the leaves/bamboo slices. This is considered an advantage over alternative engraving technologies where bit heads have to be replaced regularly.

The impact of laser engraving has been more pronounced for specially designed "laserable" materials. These include polymer and novel metal alloys.

In situations where physical alteration of a surface by engraving is undesirable, an alternative such as "marking" is available. This is a generic term that covers a broad spectrum of surfacing techniques including printing, hot-branding and laser bonding. In many instances, laser engraving machines are able to do marking that would have been done by other processes.

LASER ENGRAVING MACHINE:

A laser-engraving machine has three main parts: a laser, a controller, and a surface. The laser is like a pencil - the beam emitted from it allows the controller to trace patterns onto the surface. The controller (usually a computer) controls the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is picked to match what the laser can act on.

There are three main genres of engraving machines: The most common is the X-Y table where, usually, the workpiece (surface) is stationary and the laser moves around in X and Y directions drawing vectors. Sometimes the laser is stationary and the workpiece moves.

Sometimes the workpiece moves in the Y axis and the laser in the X axis. A second genre is for cylindrical workpieces (or flat workpieces mounted around a cylinder) where the laser effectively traverses a fine helix and on/off laser pulsing produces the desired image on a raster basis. In the third method, both the laser and workpiece are stationary and galvo mirrors move the laser beam over the workpiece surface. Laser engravers using this technology can work in either raster or vector mode.

The point where the laser (the terms "laser" and "laser beam" may be used interchangeably) touches the surface should be on the focal plane of the laser's optical system, and is usually synonymous with its focal point. This point is typically small, perhaps less than a fraction of a millimeter (depending on the optical wavelength). Only the area inside this focal point is significantly affected when the laser beam passes over the surface. The energy delivered by the laser changes the surface of the material under the focal point. It may heat up the surface and subsequently vaporize the material, or perhaps the material may fracture (known as "glass" or "glass up") and flake off the surface. This is how material is removed from the surface to create an engraving.

If the surface material is vaporized during laser engraving, ventilation through the use of blowers or a vacuum pump are almost always required to remove the noxious fumes and smoke arising from this process and for removal of debris on the surface to allow the laser to continue engraving.

A laser can remove material very efficiently because the laser beam can be designed to deliver energy to the surface in a manner which converts a high percentage of the light energy into heat. The beam is highly focused and collimated - in most non-reflective materials like wood, plastics and enamel surfaces; the conversion of light energy to heat is more than efficient. However, because of mis efficiency, the equipment used in laser engraving may heat up rather quickly. Elaborate cooling systems are required for the laser. Alternatively, the laser beam may be pulsed to decrease the amount of excessive heating. Different patterns can be engraved by programming the controller to traverse a particular path for the laser beam over time. The trace of the laser beam is carefully regulated to achieve a consistent removal depth of material. For example, criss-crossed paths are avoided to ensure that each etched surface is exposed to the laser only once, so the same amount of material is removed. The speed at which the beam moves across the material is also considered in creating engraving patterns. Changing the intensity and spread of the beam allows more flexibility in the design. For example, by changing the proportion of time (known as "duty-cycle") the laser is turned on during each pulse, the power delivered to the engraving surface can be controlled appropriately for the material.

Since the position of the laser is known exactly by the controller, it is not necessary to add barriers to the surface to prevent the laser from deviating from the prescribed engraving pattern. As a result, no resistive mask is needed in laser engraving. This is primarily why this technique is different from older engraving methods.

Laser engraving is first used to directly burn images on wood. The laser power required here is often less than 10 watts depending on the laser being used, as most are different. Hardwoods like walnut, oak, mahogany and maple produce good results. Softwoods can be judiciously engraved but tend to vaporize at less-consistent depths. Burning softwood with a fan blowing on it requires lowest power, quickest speed of cut, and enough airflow to extinguish what is trying meanwhile to ignite.

The demand for personalized jewelry has made jewelers more aware of the benefits of the laser engraving process.

Jewelers found that by using a laser, they could tackle an engraving task with greater precision. In fact, jewelers discovered that laser engraving allowed for more precision than other types of engraving. At the same time, jewelers discovered that laser applied engravings had a number of other desirable features. At one time jewelers who attempted to do laser engraving did need to use large pieces of equipment. Now the devices that perform laser engraving come in desktop units. Some entrepreneurs have placed such units in mall kiosks. That has made laser engraving jewelry much more accessible. The makers of machines for laser engraving jewelry have developed some very specialized equipment. They have designed machines that can engrave the inside of a ring. They have also created machines that have the ability to engrave the back of a watch.

A laser can cut into both flat and curved surfaces. Jewelry contains both flat and curved surfaces. That points-up the reason why jewelers have welcomed all the adaptations for the creation of laser engraved jewelry.

SUMMARY OF THE INVENTION

It is the primary object of the present invention to provide a method and processing technique of palm leaves and bamboo slices to enable preservation of the same for longer duration.

A further object of the present invention is to provide engraving or screen printing on palm leaves or bamboo stem slices, using laser engraving or screen printing technology, which can be preserved for many years.

This invention thus provides engraving/ printing on palm leaves or bamboo stem slices comprising the step of printing/engraving seasoned palm leaves using laser or stylus, removing the excess ink, followed by drying after the applications of a preservative.

The current invention of course adopts the technology of Laser engraving/ larger marking - with a computer interface. This is used to engrave anything on a palm leaf at a much faster rate. Multifold copying, CAD drawings, and letters, words, figures using any other softwares also. And any other relevant displays are also possible. Any language, any color or any font can be used to engrave. All present and future computer technology/soft wares can be used to engrave/mass produce/and circulate the manuscripts. This would help society in preserving and distributing the presently available information for the next 2000 years as how our ancestors have preserved them/manuscripts forms for the last 2000 years.

Place the leaf or bamboo stem slice on the bed of the laser engraving machine and fix it so that it is not movable; then select a) proper laser power b) proper depth of engraving/marking, c) proper speeds and start engraving. The palm leaves or bamboo stem slices are to be seasoned before engraving.

The present invention can be incorporated into the production of consumable products like palm leaves manuscripts, visiting cards on palm leaves or bamboo slices, wedding and all other types of invitations. It can also be used to engrave artistic designs on the said material.

The lifetime of printed-paper is very limited whereas the palm leaves containing engraved manuscripts have been found to be ever living i.e. thousands of years it can be as it is.

The types of palm leaves used in the invention are Palmyra and Talipot.

DETAILED DISCRIPTION OF THE INVENTION

Preparation of palm leaves or bamboo stem slices manuscripts:

The palm leaf or bamboo stem slice is removed from the tree and cleaned within 24 hours from the time it is taken out of the tree. Then the leaf or slice may be given a pre- softening treatment by dipping in hot water till it is softened. After softening, the leaves/slices are optionally earthed for some days for pre-seasoning. Leaves/slices are set tightly and leveled or cut with the help of a cutter. Then depending upon the size of the cut lealMice, two holes are made. This is for posing threads to bind the leaves/slice. The palm leaves or bamboo stem slices should be treated with boiling hot water at 60- 90°C for about 20 to 30 minutes. The softened leaves/slices are then cut to the desired shape and size and dried (not in a direct sun light). Drying in the shade ensures that the leaves/stem slices contain some amount of moisture, which will help in keeping them soft (not brittle) condition. After cutting to the desired size and shape and drying, they are made flat using weights and some special . fixtures, so that they will be free from all undulations and bends. Since the palm leaf or bamboo stem slice is brittle this process of softening is very essential. Flattening of the palm leaves or bamboo stem slices is generally carried out by placing the leaves between two wooden planks and bundle them tightly with a rope to keep them tightly held for about fifteen days.

Writing on seasoned palm leaves or bamboo stem slice:

Before starting the laser engraving, the softened leaves/slices are once again separated and cleaned to remove any fungus or undesired marks using normal water or any mild detergent or any natural detergent like lime juice or soap nut. The cleaned leaves/slices are kept in the printing/engraving machine using either a vacuum holding fixture or a frame holder to hold it flat. Vacuum holding fixture is preferred as it holds the leaves/slices in a perfect flat level.

The letters and figures in any language can be engraved or marked using laser beam engraving / marking technology or with the help of stylus, any thing may be written on this by hand also. Top edge can be taken as line and following it makes accurate straightness in engraving. The depth of engraving varies from 20 microns to 500 microns so as to get the perfect readability of the engraved matter. The laser power is kept at 10 to 40 watts max. The engraving speed is at 20 to 60 meters/ minutes and the printing density is kept at 150 to 700 dots per inch (DPI) in case of palm leaves and 150 to 1000 DPI in case of bamboo slices to get the desired good results. Then ink in any colour is applied in the engraved portion so as to highlight contents engraved the and the it is rubbed of thoroughly with a cloth or with pure cotton so that the ink remains only in the engraved portion and any extra ink here and there on the surface gets removed.

By varying the above three factors, i.e., the laser wattage, laser speed, and the DPI, one can get the desired depth of engraving i.e. from 20 microns to 500 microns for palm leaves and 50 to 1000 microns in case of bamboo slices, which will give the desired commercial value and value addition to the leaf to keep the information for thousands of years.

Vacuum fixture referred hereinabove is a fixture which holds the soft and frazil components with out damaging them by sucking the air (creating the vacuum) between the components (in our case leafs) and the fixture surface.

Preservation:

After the ink is dried, preservatives like neem oil or citrus oil is applied and dried for preserving the manuscript for hundreds of years, then two wooden planks or hard board planks are cut at least ¹A inch more (on all sides) than the size of these leaves, two holes are made at the same pitch and same place (as it is done in the leaves) and all edges are rounded off so as to remove the sharp edges on these wooden planks, then the palm leaves are placed between these two planks and a thread is passed through the holes and the whole bundle is tied with this thread and is preserved or used as a book or manuscript for generations.

One can make note of the following differences:

On jewellery more amount of material is removed and it is three dimensional engraving (3D), where as on the palm leaves the depth of the engraving varies from 20 microns to 500 microns max in case of palm leaves and 50 to lOOOmicrons in case of bamboo slices, and it is two dimensional engraving (2D).

Normal laser printing on paper involves the paper to be moved against the laser beam, where as engraving on palm leaves or bamboo stem slices involves the moving of laser beam against a fixed leaf or bamboo stem slice, so as to make required markings on the leaf or bamboo stem slice.

The life time of printed paper is very limited whereas the palm leaves containing engraved manuscripts have been found to be ever living i.e. thousands of years it can be as it is.

This non contact type of engraving technique will not damage the frazil or soft nature of palm leaves and bamboo stem slices while engraving because it will not come into contact with palm leaves / bamboo slices.

EXAMPLE:

1. Cut the leaves from the tree. 2. Take out the good leaves, clean them with normal water to remove mud, soil , and all other dust particles from the surface of the leaves , with in 24 hrs (before they get dried up). 3. Make them into bundles 25 to 50 nos. and boil them in the hot water at 60 to 90 degree centigrade for about 20 to 30 minutes. 4. Cut the flat surface of the leaf to the desired size and shape like oval, elliptical, square, rectangle, or any other shape required, with two holes to pose a thread.

5. Dry them in the shaded sun light (not direct sun light) for about one week.

6. Place these leaves between two wooden planks and bundle them tightly with a rope and keep them tightly held like this for about 15 days, so as to make the leaf flat and with out any undulations so as to make it ready for engraving / marking. 7. After this take these bundles and open them one by one and clean the leaves with the cold water to remove any fungus or any undesired marks appeared on the surface of the leaves in this process any natural detergents like lime juice or natural soap nut can be used for cleaning. 8. Dry those under normal room temperature so that a small amount of moisture about 10 to 15 % should be there in the leaf, which keeps the leaf flexible and easy to handle to engrave; now the leaf is ready for engraving.

9. Take the leaf in this condition and place it on a vacuum holding fixture, to hold it in a perfect flat level. 10. Start engraving using a laser beam (computer controlled) on the leaf in desired language, desired fonts and styles.

The above example is given with reference to palm leaves and it is to be understood that the same process can be repeated for bamboo stem slices and the depth of the engraving can be upto 1000 microns and the printing density can be varied upto 1 OOODPI.

References:

1. www.libraiT.comell.edu/preservation/librarvpreservatiori/mee/preservation/palml eafJatml 2. www.aluvihara.virusnic.org

3. www.en.wikipedia.org/wiki/Laser engraving

Claims

1. A method and processing technique of palm leaves and bamboo stem slices for preserving them for longer duration comprising the steps of: a. dipping of palm leaves/bamboo stem slices into hot water till it is softened; b. cutting of palm leaves/bamboo stem slices into required shape and size; c. dry the cut leaves/slices in shaded sunlight for about a week; and d. setting of seasoned palm leaves/bamboo slices tightly with the help of a flat surface for leveling after posing holes to enable binding.

2. A method of claim 1 wherein the hot water is maintained at a temperature of 6O⁰C to 9O⁰C for about 20 to 30 minutes.

3. A method of claim 1 wherein the palm leaves or bamboo stem slices are subjected to a pre-softening step by dipping in hot water and kept covered by mud for few days.

4. A method for laser engraving or screen printing on palm leaves or bamboo stem slices comprising the steps of: a. seasoning of palm leaves or bamboo stem slices; b. printing/ engraving seasoned palm leaves using laser or stylus; c. applying the ink of different colours on the said leaves/slices; d. removing the excess ink; and e. drying after the application of a preservative.

5. A method of claim 4 wherein the seasoning of palm leaves or bamboo stem slices comprises the steps of: a. dipping of palm leaves/bamboo stem slices into hot water till it is softened; b. cutting of palm leaves/bamboo stem slices into required shape and size; c. dry the cut leaves/slices in shaded sunlight for about a week; and d. setting of seasoned palm leaves/bamboo slices tightly with the help of a flat surface for leveling after posing holes to enable binding.

6. A method of claim 4 wherein the engraving or printing or marking is carried out in the seasoned palm leaves/bamboo stem slices by using laser beam engraving/ marking technology or with the help of stylus, to obtain the desired depth of engraving i.e. from 20 microns to 500 microns in case of palm leaves and 50 to 1000 in case of bamboo slices.

7. A method of claim 6 wherein the laser power is kept between 10 to 40 watts, the engraving speed is maintained at 20 to 60 meters/minutes and the printing density is kept at 150 to 700 dots per inch for palm leaves.

8. A method of claim 5 wherein the palm leaves/bamboo slices are cut into shapes such as oval, elliptical or square rectangle.

9. A method of claim 4 wherein the preservatives like neem oil or citrus oil is applied and dried for preserving the manuscript for hundred of years.

10. A method of claim 5 wherein the hot water is maintained at a temperature of 6O⁰C to 9O⁰C for about 20 to 30 minutes.

11. A method of claim 4, wherein the palm leaf or bamboo stem slice is fixed on the bed of the laser engraving machine with the help of vacuum fixtures

12. A method of claim 4 wherein the palm leaves or bamboo stem slices are subjected to a pre-softening step by dipping in hot water and kept covered by mud for few days.