DE2008892A1 - Process for melting a layer of thermoplastic powder onto a substrate - Google Patents

Description

Dipl.-Ing. H. Sauerland ■ Dr.-lng. R. King Patent Attorneys - 4000 Düsseldorf · Cecilienallee 7B ■ Telephone 43273a

Our files: 25 679 February 25, 1970 Il / Ro

International Nickel Limited, Thames House, Millbank, London, S. W. 1, Great Britain

"Process for melting a layer of thermoplastic powder onto a base"

The invention relates to the melting of a layer of thermoplastic powder onto an underlying one Area. It should find its main application in connection with the melting of images, those made from thermoplastic powder using electrostatic copiers or high-speed printers getting produced. But it can also be used to melt a surface powder, which is applied by other methods, for example powder, which is in its position by spraying means an aerosol has been brought.

In electrostatic copying machines, an image is formed on a receiving sheet by means of a dyed thermoplastic powder and the sheet is then exposed to a number of radiant heat generating devices which raise the temperature of the powder to the point where it melts on the Paper in his

009837/1966

reaches its final state, which is called freezing the image. In some electrostatic copier machines the powder is first distributed over the charged, photoconductive surface of a drum, from which it is transferred to untreated receiving sheets. In other machines they have the picture receiving sheets themselves have a photoconductive surface and receive the particles directly. In development on fast copying machines it is the speed of the fixing of the powder image the receiving sheet, which among other things affects the overall speed of the electrostatic copier draws a line because all other work steps are in can be carried out in a very short time.

It has now surprisingly been found that the melting of a powder layer or an image can be accomplished in a fraction of a second if one proceeds according to the invention. According to the invention, the surface on which an existing from powder image or consisting of the powder layer has been provided, exposed to a flash of radiant energy from an extremely short period (generally less than milliseconds) and an intensity sufficient, the powder on the surface to fix. In the preferred embodiment of the method according to the invention, a high energy discharge tube is used to generate the flash.

In an advantageous application, the invention is used in connection with a high speed printer for a computer. The one produced by the flash tubes

009837 / 19S5

The entire receiving surface on which the powder image is already formed can be exposed to light. However, parts of the uniformly powder-coated surface can also be exposed selectively, in order to use the powder in the form of selected lettering or characters that are printed supposed to fix.

Thermoplastic powders, such as those used in electrostatic copying, absorb electromagnetic Radiant energy over the entire infrared range of the spectrum. It is known that in general in such machines, white paper used only a small amount of infrared radiation from one Wavelength absorbed that is less than 1 micron, and that the absorption of infrared radiation with increasing wavelength up to 9 microns. Above this wavelength is the absorption of the paper equal to that of the powder image. The energy of radiant heat. generating heating devices, as they are commonly used used in copying machines to melt the image contains a high proportion of Long wavelength infrared light (5 to 20 microns). Therefore the paper is heated almost as much as the picture. As a result, the shorter infrared wavelengths allow the radiant energy with greater Efficiency, and in the preferred embodiment of the invention are accordingly flash discharge tubes high energy is used to fix powder images, most of which use their energy in the emit short-wave infrared band (0.7 to 1.2 microns). This radiation causes selective heating

009837/19 5 5

of the powder image with very little heating of the supporting paper.

Previously, if a powder image of the prolonged exposure has been exposed to a heat source, it was deemed necessary when using relatively short-wave radiation ^<: energy proceed with great caution, because overheating of the image areas, the paper below the image scorch both could also weaken Delt opposite was found that no scorching or weaknesses of this type occur if, according to the invention, the duration and intensities of the flashes are chosen so that they are sufficient to fix the image.

Although flash tubes that operate in the infrared range are desirable, normal xenon flash tubes can be used with success, since generally about 60% of the energy delivered by such a tube is in the waveband between 0.7 and 1.2 microns, where the lightning spectrum broad peaks at about 0.82 -: i; Microns, 0.88 microns and 0.98 microns. Although the speed of lightning only needs to be a small fraction of a second, the radiant energy emitted is surprisingly large. It has been found that the minimum of energy required is that of a.>. Bruning AM 2100 copier machine to melt the image obtained is approximately 1.5 joules / cm. < _A & $ &

■, fir, ·, ·, ■,

In one experiment, sheets of paper of 40 ce »it non-fixed powder images of the radiation energy a flash lamp working with an electron gun from Type Braun EF 300 exposed. That was what it was

009837/1056

2008O2

once 1 to © inje. ^ ppiermajsGhiiie vom Typ / Bruning AM 210, Q and in the other IFa ^] Le about a copier from ΐνρ Xerox 9H. $ £? ^ & the lamps stood by the paper bjetrug A / jt mja yn4 .4JLe Bliteda ^ ier 1/1100 Seci ^ nden. The color temperatujp (des BJ-itises- was 5600 ° IC and the abberg | .f 120 joules. The powder, vpll-

| n ^ e4n_e another example · A kappen-- pder- ^ r / | 4g filled Phptoblitzr _t eyelets * ¹ Wd a 3Ljym Bn S§3fU with a JQQ W MWisßlW ^ |! yerwendet identical. Dadwrß der. p ^ erfl |, che ypn sheets of paper fixed _? as they b, e4 Bryning- as well as tjej. Xerpx- ^ aschinen ver ^ βΐ? ^ Η | and gwar. in the circumference of an old man ypn mm gurp | 3 | 9§sser. These photoblit tubes are, dodeh .u | i # iant§r | iege.n rapid # erb.smoke. «They are not e ^ ssfn, suitable for use in ^ t | i-Qhey ■ iJ§spjk | .win4i .gkeit working .el ^ ktrpstati-

With 'TgiliSlftrpstat ^ sciien Kppiermasehinen earn naturally § ^ f jf§r | a] | fen: 4en yprzugj where 4er ⁱ lightning': sich, i | i§ _; .-gg ^ aijitg £? §pi§rpberflache jBrs.treckis »on the»

gefqriat; is and fixed; become 'spII. In | ^; f ^ en-'Weise'-can 'aifdpch 4 | ^ Fa | r | # b, latt

a ^ Efge, sits for 4 ^ ny ^: die ljirn! - 4e; | ^; djas r fixed

OR ₁ GlNAL INSPECTBD

Tube organs and lengths, the amount of radiant energy emitted, the reflector system and the electronic circuit for controlling the PliibÄgesQi3wiPidi.gk§i1b should be within the range of professional skills on the @ ebj.et 4 optics ujid dar electronics, Wm gß * - l ^ WANTED, means may be provided for controlling the flash of Geschwin4igkeit and performance to the: to obtain gewjLjnschte plonge to delivered ^energy,:; ;

Above is from looking up pictures on the upper τ Flat sheets of paper have been spoken in front of them, Yes, yes highlighted that unmelted, electrostatic generated images according to the method according to the invention on a multitude of differently designed upper » surfaces can be fixed, for example surfaces made of metal, glass, plastic, wood or ceramic scftero fabric or also on sensitive surface?}, which would be damaged if normal image fusing procedures were used.

Another advantage lies in the fact that 4ftfl 4as. ;, Short-wave infrared light selectively melts the powder by melting the dense part of the image and making it easier to remove the undesired dispersed background particles which ..; ·. Commonly, the older heating methods melted * ^{: 1} ^ ' ¹ - - ^: · ^ν · -' ■■■ · '■■■' ■ ■ ■■■■■■■ - · ■ ■ ·. ,,:,: ,;:.

| ^ findi4jag kjanh, as noted above, fcei Ifoch gesph> / indigiceitsdruckern are applied to Xn a »

consists of the light source for the f ^ thodfnstrahlro ^ re, whose referee consists of

ORIGINAL H4SPECTI

consists of high-intensity, rapidly extinguishing fluorescent material and receives signals from the computer in such a way that that the computer data is copied and reproduced line by line on the tube. The line reproduced characters or characters imaged by means of a lens on a continuously running paper strip with a photoconductive surface, which has previously received an electrostatic charge and the image is then with the Powder coating provided and fixed.

To further explain the invention, the drawing is used in which some exemplary embodiments for Apparatus are shown embodying the invention. Show it

Figs. 1 to 3

Flash tube arrangements for electrostatic copier machines,

Fig> 4 to 6

Apparatus for use in high speed printers,

7 shows a part of the apparatus according to FIG. 6,

Fig. 8 is a representation to illustrate a method for generating images of characters or lettering on the paper web using the apparatus of FIGS. 6 and 7 and.

. 9 shows a further embodiment of an apparatus

009837/1955

for use in a high speed printer.

In the embodiment of FIG. 1, a flash tube 10 is in a hood-shaped reflector 11 above the path of a conveyor system 12 arranged. A sheet of paper, that carries an image in the form of thermoplastic powder is moved into a position by means of the conveyor system brought below the reflector and then the effect exposed to a lightning bolt generated by the tube 10. The sheet can for example through the front A common Xerox machine and the powder image pattern from a photoconductive one Drum on which the image to be copied has been focused.

In Fig. 2, a sheet of paper 14 runs on a path below a linear type flash tube 15 that repeats is ignited to emit a multitude of flashes as the sheet passes under it. the Tube is located in a narrow reflector 11a. Fig. 3 shows an arrangement in which a number linear tubes are used which flash simultaneously to equal the entire surface of the sheet Time to expose.

The reflectors, which normally cover the tubes, have been omitted in the drawing to show the To make tube arrangement visible.

In the high speed printer of Fig. 4, a paper web 16 having a photoconductive surface

009837/1955

«Bf At; .- i- j ■> ·,.

withdrawn from a spool 17 and first passes under a corona discharge device 18 and on top of it in the path of a light spot which is generated by a cathode ray tube 19. Under control of signals supplied by a computer 20 and deflection signals emanating from a time base 21, a line of lettering or other characters is generated on the screen of the cathode ray tube and imaged on the paper web 16. This creates a latent electrostatic charge on the web. The train then runs under a developer brush 22, by means of which the thermoplastic powder is applied to the electrostatic image is brought on the web. This image is then fixed when the web is below a linearly shaped flash tube 23 passes therethrough. The carrier pulse for igniting the flash tube is from the Return signal derived from the time base 21 and on the Flash tube given via a connection 24.

Fig. 5 shows another example of an arrangement in connection with a high speed printer. In this example, the output signals of a computer 20 control the timing of the one Infrared flash tube 22b in order to project individual characters or other characters in this way on a transparent circumferential disk 23 to select. The selected characters or other characters are imaged one after the other on a paper web 24. This web is previously under a corona charger 18 and a brush 22a passed through it, covering the entirety of the paper surface with powder covers. The infrared flash tube 22 is used to this

009837/1955

To fix the powder where the image of the characters falls on the paper, while all the remaining powder is unfixed remain. The unmelted powder is then removed by means of a brush 25, so that on the Paper only melted powder remains in the shape of the projected characters. The removal of the powder can either be done electrostatically by means of an electrode whose charge has an opposite sign has the sign of the charge on the paper. Instead, the computer can create a line of character matrices in a manner similar to selecting a type line in a common line printer.

In the exemplary embodiment according to FIG. 6, a paper web 16 with a photoconductive surface is unwound from a spool 17 and passes under a corona charger before entering the beam of light that is based on a stroboscopic Iloch speed flash tube 30. The circuits 31 »through which the Flashes are triggered and the flash outputs depend, are controlled by signals that are sent by a Computer supplied. Synchronization signals are sent via a connection 33 to a scanning reflector 35 created. The scanning reflector consists of emai3 Fig. Y from a mirror 36, which is mounted on a pivot pin 37 and with an electromagnetic transducer;> ü connected is. The vibrations in the vertical plane, which are communicated to the mirror by the transducer, cause this to generate a vertical scan image on the paper, as indicated at 39. the Rotation of the shaft 40 on which the mirror is mounted causes the vertical scan image to be horizontal

BATH ORIGINAL

009837/1955

is shifted over the paper, as also "at 39 is arranged. The flashes generated by the stroboscope are laterally controlled by the computer to create light spots or to create spots of light that fall on the paper during scanning to create a cough, as indicated in FIG. 8, for example, by the thickened points. This creates a latent Generated charge image of lettering or other characters on the paper. The paper is running then under a developer brush 22, where the image pattern generated by the charges is provided with powder will. The powder is then fused onto the paper by means of a linear type flash tube 23. The flash tube is synchronized with the operation of the imaging apparatus through a link 41, which originates from the circuit 31 serving for controlling the power and for triggering.

A variation is to continuously advance the paper when scanning horizontally some kind of diagonal scanning is replaced. In a further modification, the scanning light spot can the charged, .photoconductive surface of a circumferential The drum is projected and, after the powder has been developed, the image is transferred to a paper tape in the usual way will.

Finally, the apparatus shown in FIG. 3 corresponds to that of FIG. 5, except that the infrared flash tube is replaced by an infrared laser 42 which is used for triggering and for controlling the power and in turn by the computer 32 is controlled. The laser beam falls on a scanning reflector 35 of the type shown in FIG.

003837/1955

_BATH

Claims (1)

International Nickel Limited, Thames House, Millbank, London, S. W. 1, Great Britain Patent claims: Process for melting a layer of thermoplastic powder onto the surface of a base, characterized in that the base (14, 16, 24) one Flash of radiant energy is exposed, the duration and intensity of which is chosen so that the Powder is fixed on the base. 2. The method according to claim 1, characterized that an electrostatically generated image is used as a layer of thermoplastic powder. 5. Method of fixing an electrostatically generated image in the form of thermoplastic Powder on a sheet used to receive the image, characterized in that that the thermoplastic powder is deposited on the image-receiving sheet (14, 16, 24) Flash of radiant energy is exposed, the duration and intensity of which are sufficient to cause the powder to enter to fix the sheet. 4. The method according to any one of claims 1 to 3, d a - BAD ORIGINAL 0 0 9 8 3 7/1955 characterized in that · the lightning consisting of radiant energy through Energizing a discharge tube (10, 15, 22b, 30, 42) high energy is generated. 5. The method according to claim 4, characterized that the spectrum generated by the discharge tube (10, 15, 22b, 30, 42) Light is chosen so that there is a substantial portion of wavelengths in the band of 0.75 contains up to 1 micron. 6. The method according to any one of claims 1 to 5, characterized in that the thermoplastic powder and the underlying area under a linear shaped flash tube (15) guided along and the tube is ignited so that it is during the passage of the surface (14) and the thermoplastic powder under the tube delivers a series of flashes of radiant energy, 7. The method according to any one of claims 1 to 6, characterized in that the surface on which the image is created is made of metal. 8. The method according to any one of claims 1 to 6, characterized in that the base on the surface of which the image is created consists of ceramic material. 9. The method according to claim 4, characterized by the use of a xenon 009837/1955 Flash tube · for generating the flash of radiant energy. 10. Method of selectively fixing an image in Form of thermoplastic powder on an image-receiving surface, characterized in that that the surface is provided with a layer of thermoplastic powder and parts of the layer selectively the effect be exposed to a flash of radiant energy, the duration and intensity of which are sufficient to produce the Fix selected parts of the picture, whereupon the powder from the remaining areas of the picture receiving surface is removed. 11. One-device electrostatic copying machine to create an image of an (object, which is made on a sheet in the form of a pattern charged particles are to be reproduced, characterized in that the Machine at least one high-energy discharge lamp (10, 15), means for Ignition of the discharge lamp to generate a flash of radiant energy and contains means, around the sheet (14) carrying the powder pattern the flash of radiant energy generated by the discharge lamp suspend. 12. Ilochgeschwindigkeitsdrucker, comprising means for forming an image of a Schrif tüiiges or other character to be printed by means of thermoplastic powder on a surface ge - ken η is characterized by having BAD ORIGfNAL 009837/1955 high energy discharge lamp (22b), means for exciting the discharge lamp and means, through which the surface to be printed, on which the powder image has been formed, a flash of 3 exposed to radiation energy from the discharge lamp can be. 13. High speed printer according to claim 12, characterized in that the sheet is made of flexible material with a photoconductive surface and the printer means for continuously advancing the sheet, means (18) for electrostatically charging the Sheet, means for depicting lettering to be printed or other characters on the loaded sheet, means for producing a coating (22, 22a) of thermoplastic powder contains the latent charge image of the sheet and a high-energy discharge lamp, which generates at least one flash of radiant energy, the effect of which is thermoplastic Powder image is exposed. 14. Printer according to claim 13, characterized that the means for depicting lettering or other characters consist on the sheet of a cathode ray tube (19) and the high energy -working Discharge lamp synchronous with the scanning 1. ,, .. J. en the Cathode ray tube is triggered. ^s j . A printer according to claim 12, characterized ge 'J .. e α ti is characterized in that the bildi'ormenden BATH 0 0 ^f JB 3 7/19 5 5 Means contain optics for focusing flashes of light emitted by a pulse-controlled light source go out and act on a photoconductive surface, and that deflection means are provided which cause that the focused light spots resulting from successive flashes are latent images create lettering or other characters on the surface, 16, high-speed printer, marked net by means for forming an image on one covered with thermoplastic powder Area using a pulse-controlled, infrared laser to form the image and at the same time Melting the image in place, with unwanted powder subsequently removed will. 17. High speed printer, characterized by means for generating a uniform coating on a surface to be printed, consisting of a layer of thermoplastic Powder consists of at least one high-energy discharge tube to generate at least one a flash of radiant energy, means that allow certain areas from the uniform to selectively select the coated area in order to expose it to the action of the lightning and that of this Thermoplastic powder exposed to the effect in forms of lettering or other su-printing To fix characters, and means to remove the powder from the unexposed areas of the Area. G ü 9 8 3 7/1 9 5 5 if Blank page