CN1162768A - Electrostatic printing method and apparatus employing whisker write head - Google Patents

Abstract

An electronic printing device is disclosed which uses flexible whiskers to transfer a charge corresponding to an image to a dielectric recording surface. The recording surface preferably has areas of differing conductivity so that microfields form on the dielectric surface. Ink, preferably non-charged, may then be attracted to the recording surface through dipole forces and later transferred to paper.

Description

The electrostatic printing apparatus of electrostatic printing method and use whisker write head

In general, the present invention relates to electrothermic print, more particularly, relate to a kind of contact method and make electrostatic charge be deposited on the visual device that generates on the part.

In the electrothermic print technology, for example in the technology described in patent 5325120 and 5406314, electrostatic charge is deposited on image and generates having on the slight recording surface of refusing ink character of part, to form electrostatic pattern.This electrostatic pattern comprises and the corresponding charged and territory, neutral area of electron image, can be converted to the form that can see on printed substrates.Detest ink character by what the static electric field of charge generation of deposition overcame this recording surface, and, ink is attracted on this recording surface according to electrostatic pattern.On each position of this electrostatic pattern, be transferred to normal amount on the per unit area of the ink on this recording surface or ink thickness from ink-feeding device and be directly proportional with local electric field intensity.This recording surface shifts the image that shows with contacting of printed substrates fully from this recording surface, then, this recording surface can be ready to again develop again or wipe electrostatic image.

Image generates the whole recording surface of part and makes by non electrically conductive material, as adopting in the described method of above-mentioned patent.The electrostatic charge of deposition produces charged pixel area on these recording surfaces.Image in the another kind of form described in No. 08/467200 and 469323, the patented claim that generally the has series generates the recording surface that part has anisotropic properties.Therefore, the electrostatic charge of deposition produces the non-uniform electric field that adapts with pixel on the local record surface.

Adopt the microplasma record generating the electrostatic charge pattern that forms image on the part at image, with the recording surface of any form be compatible.Though the microplasma record is a kind of effective and general technology, implements and still has some shortcomings.Several examples of these shortcomings are: the required field of ion flow that needs high voltage to drive to be produced as to set up electrostatic pattern causes igniting animating electrode (field ignitionionization electrode), pay particular attention to and avoid being used to hold a corrosion of splashing of the material in the duct that causes spark electrode, even without image transfer, also need one to safeguard electric current, so that make electrode be in stand-by state.These factors can increase the job costs of this printing equipment.

Therefore, for some application scenario, be desirable to provide a kind of picture record technology that does not need to make use to cause the igniting animating electrode.

In addition, utilize the beam type hard contact have as ' 200 and the electric finger-type described in No. 323 patented claim of ' directly to contact to write and to cause the charging of recording surface bad, because recording surface is quite coarse at microscopically.Rigid contact may be got up from this coarse recording surface " jumping ", and can not rebound in time and contact with this surface recording, to guarantee desirable electrical conductivity.In addition, hard contact described here is more crisp, therefore, can fracture or rupture in long-term use.

The present invention adopts flexible conduction " antenna " on pencil, generate the part actual contact with image, electric charge is transferred to image generates on the part, thereby and generate the electrostatic pattern that forms on part according to the figure shapeliness at this image.Pencil of the present invention is to above-mentioned, and microplasma pen recorder described in the patent of ' 120 is somewhat similar, but following main difference is arranged.' 120 patent has been announced a kind of pencil with a series of ion beam transmitters, each ion beam transmitter generates under the potential difference (PD) influence of part/pencil at image, cross the gap, give a pixel area charging on this recording surface, and of the present inventionly go out writing head and comprise that one has single the antenna perhaps matrices of many antennas or the array of pad, these matrices or pad are fixed by conductive substrate, and each matrices charges to and visual correspondent voltage.These matrices or pad by with the slip actual contact of this recording surface, electric charge is transferred on this recording surface.

As presents employed, term " antenna " is meant that a slice is superpower, superhard, and is generally the material of monocrystal.A plurality of antennas grow out from a vertical conductive substrate together with similar a plurality of parallel slips.Matrices or pad can have a single antenna, perhaps have a branch of antenna in order to set up better contact in pixel area.Generally, the diameter of antenna is 2 microns the order of magnitude, can be provided with to comprise nearly a branch of antenna of 100 antennas, a typical pixel on this suitable one this recording surface on area of 50 square microns or pad.Antenna can manufacture field with material in known any method grow out, and any material in available several suitable material makes, for example tungsten or graphite.Except suitable electric conductivity, the antenna that is used for pencil also must be flexible with chemically stable.

When use has image with the recording surface of the surf zone of different electric conductivity when generating part, the sort of image described in ' 200 He ' No. 323 patented claim above-mentioned generates part, and then the present invention can give play to the advantage of the best.This image generates part can comprise a back of the body end or basal electrode, and it is covered by the dielectric layer that one deck approaches, and has several isolated conductive regions or conducting island in this lip-deep each pixel area.Because the unevenness of recording surface and the influence of the profile of antenna, this recording surface only contacts on several points with charge member, therefore, in general, in duration of contact, have only very small amount of electric charge to be transferred on the recording surface that common medium makes, and the electric field that produces between the territory, charged and adjacent neutral area a little less than.Though the array that many antennas are formed can improve the covering situation in zone, even this low charge transfer effciency also may be restrictive factor for such structure.Yet, when the recording surface of this image generation part comprises several conducting island, even have only an antenna can in the time of nanosecond, make whole conducting island charge to the current potential of this antenna with bad the contact also of a conducting island.On this recording surface, because the edge effect of each conducting island periphery can produce the powerful non-uniform electric field that covers each pixel location.These electric fields extend on this recording surface, and descend rapidly, leave this conducting island certain distance.In addition, the electric field intensity around each conducting island is with the function of the antenna of charge deposition on conducting island according to the current potential of figure shapeliness variation.The current potential that changes according to the figure shapeliness of each antenna is selected like this, promptly makes the gathering of the electric field intensity around each conducting island be formed on the macroscopical electric field intensity on this pixel.This macroscopic view electric field intensity is the gray scale of electron image corresponding position or the monotonic quantity of colour.

When this charged recording surface is in nonconducting development medium (being preferably uncharged ink) opposite, electric field is by the dielectric polorization effect, in this medium, induce an electric moment of dipole, this medium is attracted on the charging zone of this recording surface then by the dielectrophoresis effect.The amount that medium is attracted to this charging zone is directly proportional with corresponding electric field intensity.Like this, this development medium will be stored in around each conducting island, and its amount is along with increasing monotonously in the increase of the electric field intensity of that position, develop out thereby will be recorded in the electron image that this image generates on part.Yet, also can use charged ink, like this, charged ink attracted on this recording surface by the charge compensation principle.Though this can reduce the electric contacting efficiency between the zone of the plating on antenna and the dielectric surface, yet, non-conductive and the conductive region that image generates part also can cover with the coating of detesting ink, to guarantee that ink is only according to the visual electrostatic pattern that deposits, and be bonded on this recording surface, when ink transfer is to printed substrates, just can clearly reproduce this image like this.

Will be more readily understood in the detailed description of the present invention that above discussion is carried out below in conjunction with the accompanying drawings, wherein:

Fig. 1 is the stereographic map that comprises the printing equipment of pencil of the present invention;

Fig. 2 is the backplan of the pencil embodiment of device shown in Figure 1;

Fig. 3 is got along the III-III line, the sectional view of the ratio amplification that the pencil of presentation graphs 2 combines with image generation part;

Fig. 4 is the partial cross section figure of preferred recording surface; With

Fig. 5 A and 5B are the recording surface stereographic map partly that has the anisotropic properties of conducting island, and the pencil among Fig. 5 B is reduced representation.

For the purpose of clear expression, these figure not necessarily draw in proportion.

Fig. 1 represents that according to printing equipment of the present invention it comprises a rotating paper web 10.This paper web 10 is used to support the printed substrates such as roll web W one class.Image generates part 12 and is parallel to paper web 10 placements, and roll web W can generate the gap that forms between the part 12 by this paper web 10 and image.The placed around that generates part 12 at image the e-book writing head 14 with tentaculiform charging part, with nonconducting be that the ink of electric neutrality is added to image and generates ink head 16 on the part 12, generate ink transfer station that the cylindrical shape gap between part 12 and the ink head 16 constitutes and wiping 22 by image.The work of all these elements is all by controller 24 controls.

Controller 24 receives the streamed input signal of digital data.The gray scale or the colour of the image that the input signal representative of this data stream type can finally be reproduced on this roll web.Under the situation of printing color printed matter, Fig. 1 represents to print color composition or feature, for example blue green composition printing unit of source document.For the printed matter of four kinds of colors, generate the downstream of part 12 at image, also place three printing units, be used for other color composition, i.e. peony, yellow and black are as described in No. 4792860, United States Patent (USP).Another scheme is, with device repacking shown in Figure 1, allows it comprise that a plurality of color inks add the station, makes this device itself can print all four kinds of colors, as analogy, above-mentioned described in the patent of ' 120 like that.

Represent the serial data of the order of the different colours composition on the colored original paper to be added on this device.For example, this device can receive data by the order of blue green, peony, yellow and black.Optimum scheme is that controller 24 has mass storage 24a, makes the necessary lot of data of this device work in order to storage.

In order on roll web W, to print controller 24 control pencils 14.When image generated part 12 and rotates, this pencil 14 generated the corresponding electrostatic image of at least a color composition in the shades of colour composition of record and input traffic representative on recording surface 12 a of part at image.

Ink head 16 can be to above-mentioned described in ' 860 or ' 120 patent to add China ink similar, its supplies with the thermoplasticity ink of molten state.This thermoplasticity ink is made up of the granules of pigments of a kind of color in four kinds of print colors that are dispersed in the cementing agent.Image generates the recording surface 12a of part, except the position that need are charged by pencil 14, can cover slightly one deck very thin detest ink material (inkophobic material), like this, ink just can not stick to this image and generate on this part surface of part.For example, if generate the image that will draw blue green on the part 12 at image, then this ink head 16 need be sent blue green ink.The result, electrostatic image on the recording surface 12a of image generation part is advanced, during by this ink head 16, the blue green ink that flows out from this ink 16 is obtained by this visual charging zone, thereby shows a blue green image on the recording surface 12a of this image generation part.As described in ' 860 He ' 120 patent above-mentioned, image generates part 12 and will heat, and is molten state with the ink that remains on this recording surface 12a.At this moment the ink of this fusing sticks on the surface of this visual charging zone.

As following will be explained in more detail, the quantity of ink that charging zone picked up that image generates on the part recording surface 12a is directly proportional with the electric field intensity of sending from this charging zone.Variation in the visual upper electric field intensity of this recording surface 12a is carried out the reproduction of whole gray scale easily.

When this image generation part 12 was rotated further, the part of showing of the image on this recording surface 12a advanced to the ink transfer station 18 that is made of the gap between paper web 10 and the image generation part 12.Controller 24 is controlled at the position of image on the image generation part 12.When image shows, and advance when generating gap between the part 12 by paper web 10 and image, the image that shows just is transferred on the appropriate position of roll web W.At transfer station 18 places, ink is to shift completely from the recording surface 12a that image generates part to the transfer of roll web W, because this transfer is the state exchange by ink, is undertaken by thermodynamic (al) mode.On ink and the osculatory than cool roll web W, ink is converted to solid state by the liquid condition of heat fusing.

Now, the charging zone that this image generates the recording surface 12a of part does not have ink, and this charging zone advances by wiping 22.This wiping headband has such as ultraviolet radiation one class device, makes this recording surface 12a conduction, and like this, the electric charge on this recording surface scatters and disappears.Therefore, when the recording surface 12a that generates part when this image came out from this wiping 22, this recording surface 12a was not charged fully, and generated next time or in the revolution of following of part 12 at image, can be by pencil 14 imaging once more.Simultaneously, represent a kind of color composition of former image, for example the image of blue green composition then is printed on the roll web W.

Printing equipment difference described in device shown in Figure 1 and the above-mentioned patent mainly is two elements: pencil 14 and image generate part 12.In the present invention, pencil 14 comprises an array of being made up of many antenna matrices (charge member), and each antenna matrices has at least one antenna, and this antenna flexibly contacts with the recording surface 12a of image generation part 12.When the corresponding pixel area of different contact points and this recording surface was relative, controller 24 was added in the voltage relevant with image on this different contact point.

Fig. 2 and Fig. 3 express this whisker write head 14 in more detail.Supporting member 40 made of insulating material extends on the whole width of this image generation part 12.A series of different conductive lead wire films 42 on this supporting member 40, have been laid.The lead-in wire film of each conduction is exactly matrices at conduction antenna 46 places or fills up voltage lead 44, that lead to controller 24.Like this, just provide according to the device of electron image to matrices 44 chargings.These films can pass through, and for example, corrosion is deposited on a continuous metal level on the supporting member 40 and makes.Each antenna matrices 44 comprises the substrate 44a of a conduction, it and a corresponding lead-in wire film 42 and an array electric connection that is grown in the antenna 46 there.The footprint of each group antenna corresponding to, and limit the area in image pixel district.Lead-in wire film 42 is not protected by insulation course 48 by the part that substrate covers.In writing operating process, the rotation of part 12 causes because image generates, and is placed on the piston shoes 50 that image generates on the recording surface 12a of part at the sliding force on the pencil 14 and absorbs.

The flexible assurance of antenna 46, when this image generated the part rotation by this pencil 14, antenna 46 and this recording surface be Mechanical Contact slightly.The experiment that antenna carried out to graphite system shows, generates at antenna and image with plane of all the sort of grindings as described below between the recording surface 12a of part 12 to have powerful electrostatic attraction.If recording surface 12a does not have dust or chemical pollutant, or thick dielectric film, then antenna can tripping or can not be set up close contacting with this recording surface.In addition, by the electrostatic attraction of the flexible antenna that is deposited on the charge generation on this recording surface 12a this antenna is offset towards recording surface, thereby has promoted electric contact.

Usually, antenna is made by high, the superhard single crystal material of intensity, and it generally vertically stretches out from the substrate 44a of conduction, as shown in Figure 3.Antenna can grow out with any method in the material processing field, for example comprise, article " the nearest progress of wide area field emission cold cathode " (" vacuum " magazine at D.Stewart and P.Wilson, 30 volumes, 11/12 phase) described in H.E.Cline in the method described in " the eutectiferous spininess of Ni-W (multineedle) field emission " literary composition (" applicating physical magazine " 41 volume the 1st phases (in January, 1970)).Antenna can be by suitable material, and for example any material in tungsten or the graphite is made.Except suitable electric conductivity, the antenna that is used for pencil must have flexible and chemical stability.

With above-mentioned image described in ' 120 and ' 314 patents to generate part different, this image generates part 12 and has anisotropic recording surface 12a.Therefore, in writing operating process, the electric charge skewness on this recording surface 12a from this pencil 14 obtains generates the electric field that stretches on the part surface thereby formed at this image.Like this, when this image generated part 12 and turns to the position of these inhomogeneous charged zones on the opposite of this ink head 16, this charging zone was obtained ink by the dielectrophoresis process from this ink head.That is, particles of ink is polarized by the non-uniform electric field on this recording surface 12a, and is attracted on the charging zone of cylindrical shape recording surface 12a.On this charging zone, the amount of electric field is the strongest, and this electric field amount is dull increasing along with the increase of this charging zone electric field intensity.

Can be clear that in Fig. 1 and Fig. 4 image generates the fuse 60 that part 12 comprises a rigidity, it can be made in steel or aluminum.Best, this fuse has groove, as shown in the figure, to reduce its weight and to make air pass through this fuse circulation, makes the fuse cooling.A sleeve 62 made from adiabatic and material that electrical insulation properties is good such as pottery is arranged around the fuse 60.On the surface of sleeve 62, be coated with for example metallic copper of layer of conductive material 64.This conductive layer generates the ground plane (ground plane) of part 12 as this image.

It is thin to wrap up one deck around conductive layer 64, for example 1 micron dielectric material with very high resistivity that (μ m) is thick, for example thin layer 66 made of silicon nitride or sapphire.On this dielectric layer 66, make the pattern of a plurality of conducting islands, can make this dielectric layer 66 have anisotropic properties.These conducting islands and conductive layer 64 electric insulations, and also electric insulation mutually.This conducting island 68 can make the form of the conduction spot, lead or the passage that are coated in the lip-deep small weak point of this dielectric layer 66.Have the zone that electric conductivity changes in order to form the surface, also can adopt additive method to make the surface have anisotropic character, for example metal embeds the method in the dielectric layer.Though whisker write head is best and have the surface engagement of anisotropic properties, if only use on the dielectric surface of common homogeneous, whisker write head also has some advantages, and is for example long than the pencil life-span of Metal Contact formula.Fig. 4 represents that also image generates on the part 12 can be provided with the extremely thin external coating of one deck 72, for example, teflon (teflon), it has the ink of detesting character.Though, this surface coating 72 may reduce electric charge generates the part surface to this image from this antenna desired transfer, but this coating can prevent ink and be bonded on the territory, neutral area of this cylindrical shape recording surface 12a, and should reduce to minimum by lip-deep ink smudge.

Fig. 5 A represents the possible collocation method of conducting island 68 on the pixel area 70: the row and column by form of straight lines is arranged, and for example, arranges conducting island on 2 * 2 on each pixel area 70.In order to represent conveniently, in the drawings, conducting island 68 is represented to such an extent that size is big and be spaced from each other broad.Yet in fact, the diameter of this conducting island may have only several microns (μ m) and separate each other less than a micron (μ m).Obviously, also can adopt other configuration modes.The conducting island configuration mode of each pixel area can be periodic, or fully arbitrarily.Yet, with pencil antenna 46 relatively, the size of conducting island 68 should be enough big, with guarantee when this pencil when each passes through pixel area 70 above, this antenna contact and should the recording surface of image generation part between the contact that can be necessary.That Fig. 5 A represents is this cylindrical shape recording surface 12a that does not have coating.

Like this, the contact of the slip antenna by pencil 14 can be in the following manner, and electron image directly draws on image generates the recording surface with anisotropic properties 12 of part 12.According to the difference of electron image, be added in the conducting island 68 that the voltage relevant with image on the antenna 46 gives electric charge pixel area 70.The pixel working method of the whisker write head shown in Fig. 5 B presentation graphs 2 and 3.The size of each antenna 46 can be quite little, because, charging to the full current potential of corresponding antenna 46 fully in order to make conducting island, this antenna only needs in a short period of time (the nanosecond order of magnitude) to contact with corresponding conducting island 68 on one point.Electric field line F laterally penetrates from each conduction spot, and ink is attracted around each conduction spot.Therefore, the existence of conducting island has strengthened the effect that should image generates part 12 greatly because with contact the 30 electric fields comparisons that produce by the narrow line on common dielectric surface, conducting island can produce stronger electric field.Dielectric layer 66 is thin more, and then the current potential around each conduction spot is more near earthing potential (it is desirable to produce highly horizontal electric field).

Therefore, the charging zone that generates part 12 when image turns to when relative with ink head 16, non-uniform electric field on each conduction speckle displacement makes the development dielectric polorization, and by the medium electrophoretic action, particles of ink is attracted on the recording surface 12a of image generation part.The amount of this particles of ink is along with the electric charge of each conduction spot increases and dull increasing.

Can also work as in the time range that this pencil 14 is detained in a single pixel area, with pulse mode writing voltage is changed several times between the desirable magnitude of voltage of zero-sum, and uneven CHARGE DISTRIBUTION is generated on the recording surface 12a of part at this image.In order to produce these pulses, it is suitable using 300 hertz alternating-current voltage source, and should generate the speed motion of the recording surface of part with 1 meter per second by image this moment.

Above-mentioned image with charged anisotropic properties surface generates part and can cooperatively interact greater than any other electrically non-conductive material of 1 with nonconducting development medium or specific inductive capacity.Though, we have illustrated the present invention who uses in the printing equipment that comprises the ink head that uses the thermoplasticity ink, but described printing equipment also can be used to receive the charged or uncharged toner of going up solid, not charged and nonconducting ink and in bulk or aerosol-type.

As can be seen, the above very favorable method of having represented a kind of design and having made the ink that is used for electrothermic print.As mentioned above, can imagine to draw that this whisker write head also can use with having image generation part common, uniform dielectric surface.Terminology used here and expression way are term as an illustration, rather than restriction, when using these terms and expression way, do not get rid of with shown in and the thing of described characteristics or a part of characteristics equivalence, therefore, in the claims of the present invention scope, can do various changes.

Claims (20)

1, a kind of device that is used to draw with the corresponding electrostatic pattern of electron image, it comprises:

Image with recording surface generates part; With

One to be used for electrostatic charge is transferred to pencil on this recording surface, to it is characterized in that in order contacting with this recording surface, this pencil has many antennas.

2, device as claimed in claim 1 is characterized in that, it comprises that also one is used for ink transfer to this image is generated ink transfer station on part.

3, device as claimed in claim 2 is characterized in that, this ink is charged ink not.

4, device as claimed in claim 1 is characterized in that, this image generate part comprise a conductive layer, one be placed on this above conductive layer dielectric layer and be placed on conducting island on this dielectric layer.

5, device as claimed in claim 1 is characterized in that, this recording surface is anisotropic dielectric surface.

6, device as claimed in claim 1 is characterized in that, this recording surface is common dielectric surface.

7, device as claimed in claim 1 is characterized in that, this pencil comprises a series of conductive pad, and each conductive pad has at least an antenna to stretch out from this.

8, device as claimed in claim 7 is characterized in that, each pad comprises many antennas.

9, device as claimed in claim 7 is characterized in that, each fills up corresponding to a pixel will writing on this recording surface.

10, device as claimed in claim 1 is characterized in that, antenna is for to be made by a kind of material in graphite or the tungsten.

11, device as claimed in claim 1 is characterized in that, this pencil also comprises piston shoes that contact with this recording surface.

12, device that is used to write with the corresponding electrostatic pattern of electron image, it comprises:

Image with recording surface generates part; With

One is used for electrostatic charge is transferred to pencil on this recording surface, it is characterized in that, this pencil has an array of being made up of a plurality of charge members, is used for writing on this recording surface, and each charge member has at least one antenna to stretch out from this.

13, device as claimed in claim 12 is characterized in that, it comprises that also one is used for ink transfer to this image is generated ink transfer station on part.

14, device as claimed in claim 13 is characterized in that, ink is uncharged ink.

15, device as claimed in claim 12 is characterized in that, this image generates part and comprises that a conductive layer, one are placed on the dielectric layer on this conductive layer and are placed on conducting island on this dielectric layer.

16, device as claimed in claim 12 is characterized in that, this recording surface is anisotropic dielectric surface.

17, device as claimed in claim 12 is characterized in that, this recording surface is common dielectric surface.

18, device as claimed in claim 12 is characterized in that, each charge member comprises many antennas.

19, a kind of on recording surface the method for recording picture, this method comprises the following steps:

A, generation and visual corresponding digital data, this image is printed on the printed substrates with the form that can see the most at last;

B, give the charging of the pencil with many charge members, each charge member has an antenna at least, and this pencil charges according to this numerical data; With

C, contact with antenna by making this recording surface, with the charge transport on the charge member to this recording surface.

20, method as claimed in claim 19 is characterized in that, it also is included in after charge transport goes out, with the step of ink transport to this recording surface.

Images