According to the present invention there is provided a heat mode imaging element for providing a lithographic printing plate consisting of a lithographic base with a hydrophilic surface and a top layer that is sensitive to IR-radiation, comprises a polymer soluble in an aqueous alkaline solution, and is unpenetrable for an aqueous alkaline developer, characterized in that said top layer comprises a polysiloxane surfactant.

The present invention relates to a heat mode imaging element comprising an IR sensitive top layer for preparing a lithographic printing plate.
More specifically the invention is related to a heat mode imaging element for preparing a lithographic printing plate whereof the difference in the top layer of being penetrated and/or solubilised in the exposed areas and in the non-exposed areas by an aqueous developer is increased.
Lithography is the process of printing from specially prepared surfaces, some areas of which are capable of accepting lithographic ink, whereas other areas, when moistened with water, will not accept the ink. The areas which accept ink form the printing image areas and the ink-rejecting areas form the background areas.
In the art of photolithography, a photographic material is made imagewise receptive to oily or greasy inks in the photo-exposed (negative-working) or in the non-exposed areas (positive-working) on a hydrophilic background.
In the production of common lithographic printing plates, also called surface litho plates or planographic printing plates, a support that has affinity to water or obtains such affinity by chemical treatment is coated with a thin layer of a photosensitive composition. Coatings for that purpose include light-sensitive polymer layers containing diazo compounds, dichromate-sensitized hydrophilic colloids and a large variety of synthetic photopolymers. Particularly diazo-sensitized systems are widely used.
Upon imagewise exposure of the light-sensitive layer the exposed image areas become insoluble and the unexposed areas remain soluble. The plate is then developed with a suitable liquid to remove the diazonium salt or diazo resin in the unexposed areas.
Alternatively, printing plates are known that include a photosensitive coating that upon image-wise exposure is rendered soluble at the exposed areas. Subsequent development then removes the exposed areas. A typical example of such photosensitive coating is a quinone-diazide based coating.
Typically, the above described photographic materials from which the printing plates are made are camera-exposed through a photographic film that contains the image that is to be reproduced in a lithographic printing process. Such method of working is cumbersome and labor intensive. However, on the other hand, the printing plates thus obtained are of superior lithographic quality.
Attempts have thus been made to eliminate the need for a photographic film in the above process and in particular to obtain a printing plate directly from computer data representing the image to be reproduced. However the photosensitive coating is not sensitive enough to be directly exposed with a laser. Therefor it has been proposed to coat a silver halide layer on top of the photosensitive coating. The silver halide may then directly be exposed by means of a laser under the control of a computer. Subsequently, the silver halide layer is developed leaving a silver image on top of the photosensitive coating. That silver image then serves as a mask in an overall exposure of the photosensitive coating. After the overall exposure the silver image is removed and the photosensitive coating is developed. Such method is disclosed in for example JP-A-60-61 752 but has the disadvantage that a complex development and associated developing liquids are needed.
GB-1 492 070 discloses a method wherein a metal layer or a layer containing carbon black is provided on a photosensitive coating. This metal layer is then ablated by means of a laser so that an image mask on the photosensitive layer is obtained. The photosensitive layer is then overall exposed by UV-light through the image mask. After removal of the image mask, the photosensitive layer is developed to obtain a printing plate. This method however still has the disadvantage that the image mask has to be removed prior to development of the photosensitive layer by a cumbersome processing.
Furthermore methods are known for making printing plates involving the use of imaging elements that are heat-sensitive rather than photosensitive. A particular disadvantage of photosensitive imaging elements such as described above for making a printing plate is that they have to be shielded from the light. Furthermore they have a problem of sensitivity in view of the storage stability and they show a lower resolution. The trend towards heat mode printing plate precursors is clearly seen on the market.
For example, Research Disclosure no. 33303 of January 1992 discloses a heat mode imaging element comprising on a support a cross-linked hydrophilic layer containing thermoplastic polymer particles and an infrared absorbing pigment such as e.g. carbon black. By image-wise exposure to an infrared laser, the thermoplastic polymer particles are image-wise coagulated thereby rendering the surface of the imaging element at these areas ink-acceptant without any further development. A disadvantage of this method is that the printing plate obtained is easily damaged since the non-printing areas may become ink accepting when some pressure is applied thereto. Moreover, under critical conditions, the lithographic performance of such a printing plate may be poor and accordingly such printing plate has little lithographic printing latitude.
U.S. Pat. No. 4,708,925 discloses imaging elements including a photosensitive composition comprising an alkali-soluble novolac resin and an onium-salt. This composition may optionally contain an IR-sensitizer. After image-wise exposing said imaging element to UV -visible-or IR-radiation followed by a development step with an aqueous alkali liquid there is obtained a positive or negative working printing plate. The printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor.
EP-A-625 728 discloses an imaging element comprising a layer which is sensitive to UV- and IR-irradiation and which may be positive or negative working. This layer comprises a resole resin, a novolac resin, a latent Bronsted acid and an IR-absorbing substance. The printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor.
U.S. Pat. No. 5,340,699 is almost identical with EP-A-625 728 but discloses the method for obtaining a negative working IR-laser recording imaging element. The IR-sensitive layer comprises a resole resin, a novolac resin, a latent Bronsted acid and an IR-absorbing substance. The printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor.
Furthermore EP-A-678 380 discloses a method wherein a protective layer is provided on a grained metal support underlying a laser-ablatable surface layer. Upon image-wise exposure the surface layer is fully ablated as well as some parts of the protective layer. The printing plate is then treated with a cleaning solution to remove the residu of the protective layer and thereby exposing the hydrophilic surface layer.
GB-A-1 208 415 discloses a method of recording information comprising information-wise heating a recording material comprising a support bearing, with or without an interlayer a heat-sensitive recording layer constituted so that such information-wise heating creates a record of the information in terms of a difference in the water permeabilities of different areas of the recording layer, treating the recording material with an aqueous liquid which penetrates through the water-permeable or more water-permeable areas of the recording layer and is constituted so as to effect a permanent physical and/or chemical change of at least the surface portions of the underlying support or inter-layer in the corresponding areas, and removing the whole of the recording layer to expose said inforlmation-wise changed support or interlayer.
EP-A-527.369 discloses a light sensitive recording material comprising a support and a positive working light sensitive layer with a rough surface, which comprises as light sensitive compound at least a 1,2-quinonediazide and as water insoluble and in water-alkaline solutions soluble or swellable binder a polycondensate or polymer and a filler, wherein the light-sensitive layer at a layer weight of 3 g/m2 or less (i) comprises as filler silica with a mean diameter from 3 to 5 xcexcm and a final limit of 15 xcexcm in an amount, which yields a slipperiness according to Beck from 20 till 100 seconds and (ii) furthermore comprises a surfactant with polysiloxane units.
EP-A- 823 327 discloses a positive photosensitive composition showing a difference in solubility in an alkali developer as between an exposed portion and a non-exposed portion, which comprises, as components inducing the difference in solubility, (a) a photo-thermal conversion material, and (b) a high molecular compound, of which the solubility in an alkali developer is changeable mainly by a change other than a chemical change.
EP-A- 97 200 588.8 discloses a heat mode imaging element for making lithographic printing plates comprising on a lithographic base having a hydrophilic surface an intermediate layer comprising a polymer, soluble in an aqueous alkaline solution and a top layer that is sensitive to IR-radiation wherein said top layer upon exposure to IR-radiation has a decreased or increased capacity for being penetrated and/or solubilised by an aqueous alkaline solution.
EP-A- 97 203 129.8 and EP-A- 97 203 132.2 disclose a heat mode imaging element consisting of a lithographic base with a hydrophilic surface and a top layer which top layer is sensitive to IR-radiation, comprises a polymer, soluble in an aqueous alkaline solution and is unpenetrable for an alkaline developer containing SiO2 as silicates
Said last two heat-mode imaging elements have the disadvantage that the difference between the solubility in the exposed areas and in the non-exposed areas is not very great so that also non-exposed areas are dissolved during the processing of said element so that said plates could not be used as lithographic plates.
It is an object of the invention to provide a heat mode imaging element for making lithographic printing plates in an easy way.
It is another object of the invention to provide a heat mode sensitive imaging element for making positive lithographic printing plates having excellent printing properties, developable in a selective, rapid, convenient and ecological way.
It is further an object of the present invention to provide a heat mode sensitive imaging element for making positive lithographic printing plates having a high infrared sensitivity.
It is also an object of the present invention to provide a heat mode sensitive imaging element for making positive lithographic printing plates wich has a great difference in developability in a developer between the exposed areas and the non-exposed areas.
Further objects of the present invention will become clear from the description hereinafter.
According to the present invention there is provided a heat mode imaging element for providing a lithographic printing plate consisting of a lithographic base with a hydrophilic surface and a top layer that is sensitive to IR-radiation, comprises a polymer soluble in an aqueous alkaline solution, and is unpenetrable for an aqueous alkaline developer, characterized in that said top layer comprises a polysiloxane surfactant.
It has been found that a heat-sensitive imaging element according to the invention can be obtained in an easy way, which yields a lithographic printing plate of high quality.
The top layer comprises a polysiloxane surfactant, more preferably a combination of at least two polysiloxane surfactants. Said surfactant can be a cationic, an anionc or an amphoteric surfactant, but is preferably a non-ionic surfactant. The amount of surfactant lies preferably in the range from 0.001 to 0.3 g/m2, more preferably in the range from 0.003 to 0.100 g/m2. The surfactant has in water preferably a surface tension at the critical micelle concentration of less than 35 10xe2x88x923 N/m.
The IR-sensitive layer, in accordance with the present invention comprises an IR-dye or pigment and a polymer, soluble in an aqueous alkaline solution. A mixture of IR-dyes or pigments may be used, but it is preferred to use only one IR-dye or pigment. Preferably said IR-dyes are IR-cyanines dyes. Particularly useful IR-cyanine dyes are cyanines dyes with two indolenine groups. Most preferably is compound I with the structure as indicated
Particularly useful IR-absorbing pigments are carbon black, metal carbides, borides, nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze family but lacking the A component e.g. WO2.9. It is also possible to use conductive polymer dispersion such as polypyrrole or polyaniline-based conductive polymer dispersions. The lithographic performance and in particular the print endurance obtained depends on the heat-sensitivity of the imaging element. In this respect it has been found that carbon black yields very good and favorable results. Suitable IR-dyes are also those mentioned in EP-A- 97 203 129.8.
The IR-dyes or pigments are present preferably in an amount between 2 and 50 parts, more preferably between 5 and 15 parts by weight of the total amount of said IR-sensitive top layer.
The alkali soluble polymers used in this layer are preferably hydrophobic and ink accepting polymers as used in conventional positive or negative working PS-plates e.g. carboxy substituted polymers etc. More preferably is a phenolic resin such as polymer containing hydroxystyrene units or a novolac polymer. Most preferred is a novolac polymer. Typical examples of these polymers are descibed in DE-A- 4 007 428, DE-A- 4 027 301 and DE-A- 4 445 820. The hydrophobic polymer used in connection with the present invention is further characterised by insolubility in water and at least partial solubility/swellability in an alkaline solution and/or at least partial solubility in water when combined with a cosolvent.
Furthermore this IR-sensitive layer is preferably a visible light- and UV-light desensitised layer. Still further said layer is preferably thermally hardenable. This preferably visible light- and UV-light desensitised layer does not comprise photosensitive ingredients such as diazo compounds, photoacids, photoinitiators, quinone diazides, sensitisers etc. which absorb in the wavelength range of 250 nm to 650 nm. In this way a daylight stable printing plate may be obtained.
Said IR-sensitive layer preferably also includes a low molecular acid, more preferably a carboxylic acid, still more preferably a benzoic acid, most preferably 3,4,5-trimethoxybenzoic acid or a benzofenone, more preferably trihydroxybenzofenone.
The ratio between the total amount of low molecular acid or benzofenone and polymer in the IR-sensitive layer preferably ranges from 2:98 to 40:60, more preferably from 5:95 to 30:70. The total amount of said IR-sensitive layer preferably ranges from 0.1 to 10 g/m2, more preferably from 0.3 to 2 g/m2.
In the imaging element according to the present invention, the lithographic base may be an anodised aluminum. A particularly preferred lithographic base is an electrochemically grained and anodised aluminum support. The anodised aluminum support may be treated to improve the hydrophilic properties of its surface. For example, the aluminum support may be silicated by treating its surface with sodium silicate solution at elevated temperature, e.g. 95xc2x0 C. Alternatively, a phosphate treatment may be applied which involves treating the aluminum oxide surface with a phosphate solution that may further contain an inorganic fluoride. Further, the aluminum oxide surface may be rinsed with a citric acid or citrate solution. This treatment may be carried out at room temperature or may be carried out at a slightly elevated temperature of about 30 to 50xc2x0 C. A further interesting treatment involves rinsing the aluminum oxide surface with a bicarbonate solution. Still further, the aluminum oxide surface may be treated with polyvinylphosphonic acid, polyvinylmethylphosphonic acid, phosphoric acid esters of polyvinyl alcohol, polyvinylsulphonic acid, polyvinylbenzenesulphonic acid, sulphuric acid esters of polyvinyl alcohol, and acetals of polyvinyl alcohols formed by reaction with a sulphonated aliphatic aldehyde It is further evident that one or more of these post treatments may be carried out alone or in combination. More detailed descriptions of these treatments are given in GB-A- 1 084 070, DE-A- 4 423 140, DE-A- 4 417 907, EP-A- 659 909, EP-A- 537 633, DE-A- 4 001 466, EP-A- 292 801, EP-A- 291 760 and U.S. Pat. No. 4,458,005.
According to another mode in connection with the present invention, the lithographic base having a hydrophilic surface comprises a flexible support, such as e.g. paper or plastic film, provided with a cross-linked hydrophilic layer. A particularly suitable cross-linked hydrophilic layer may be obtained from a hydrophilic binder cross-linked with a cross-linking agent such as formaldehyde, glyoxal, polyisocyanate or a hydrolysed tetra-alkylorthosilicate. The latter is particularly preferred.
As hydrophilic binder there may be used hydrophilic (co)polymers such as for example, homopolymers and copolymers of vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride/vinylmethylether copolymers. The hydrophilicity of the (co)polymer or (co)polymer mixture used is preferably the same as or higher than the hydrophilicity of polyvinyl acetate hydrolyzed to at least an extent of 60 percent by weight, preferably 80 percent by weight.
The amount of crosslinking agent, in particular of tetraalkyl orthosilicate, is preferably at least 0.2 parts by weight per part by weight of hydrophilic binder, more preferably between 0.5 and 5 parts by weight, most preferably between 1.0 parts by weight and 3 parts by weight.
A cross-linked hydrophilic layer in a lithographic base used in accordance with the present embodiment preferably also contains substances that increase the mechanical strength and the porosity of the layer. For this purpose colloidal silica may be used. The colloidal silica employed may be in the form of any commercially available water-dispersion of colloidal silica for example having an average particle size up to 40 nm, e.g. 20 nm. In addition inert particles of larger size than the colloidal silica may be added e.g. silica prepared according to Stxc3x6ber as described in J. Colloid and Interface Sci., Vol. 26, 1968, pages 62 to 69 or alumina particles or particles having an average diameter of at least 100 nm which are particles of titanium dioxide or other heavy metal oxides. By incorporating these particles the surface of the cross-linked hydrophilic layer is given a uniform rough texture consisting of microscopic hills and valleys, which serve as storage places for water in background areas.
The thickness of a cross-linked hydrophilic layer in a lithographic base in accordance with this embodiment may vary in the range of 0.2 to 25 xcexcm and is preferably 1 to 10 xcexcm.
Particular examples of suitable cross-linked hydrophilic layers for use in accordance with the present invention are disclosed in EP-A- 601 240, GB-P- 1 419 512, FR-P- 2 300 354, U.S. Pat. No. 3,971,660, U.S. Pat. No. 4,284,705 and EP-A- 514 490.
As flexible support of a lithographic base in connection with the present embodiment it is particularly preferred to use a plastic film e.g. substrated polyethylene terephthalate film, cellulose acetate film, polystyrene film, polycarbonate film etc. . . . The plastic film support may be opaque or transparent.
It is particularly preferred to use a polyester film support to which an adhesion improving layer has been provided. Particularly suitable adhesion improving layers for use in accordance with the present invention comprise a hydrophilic binder and colloidal silica as disclosed in EP-A- 619 524, EP-A- 620 502 and EP-A- 619 525. Preferably, the amount of silica in the adhesion improving layer is between 200 mg per m2 and 750 mg per m2. Further, the ratio of silica to hydrophilic binder is preferably more than 1 and the surface area of the colloidal silica is preferably at least 300 m2 per gram, more preferably at least 500 m2 per gram.
In the IR-sensitive layer a difference in the capacity of being penetrated and/or solubilised by the alkaline developer is generated upon image-wise exposure for an alkaline developer according to the invention.
Image-wise exposure in connection with the present invention is an image-wise scanning exposure involving the use of a laser that operates in the infrared or near-infrared, i.e. wavelength range of 700-1500 nm. Most preferred are laser diodes emitting in the near-infrared. Exposure of the imaging element may be performed with lasers with a short as well as with lasers with a long pixel dwell time. Preferred are lasers with a pixel dwell time between 0.005 xcexcs and 20 xcexcs.
After the image-wise exposure the heat mode imaging element is developed by rinsing it with an aqueous alkaline solution. The aqueous alkaline solutions used in the present invention are those that are used for developing conventional positive working presensitised printing plates preferably containing SiO2 in the form of silicates and having preferably a pH between 11.5 and 14. Thus the imaged parts of the top layer that were rendered more penetrable for the aqueous alkaline solution upon exposure are cleaned-out whereby a positive working printing plate is obtained.
In the present invention, the composition of the developer used is also very important.
Therefore, to perform development processing stably for a long time period particularly important are qualities such as strength of alkali and the concentration of silicates in the developer. Under such circumstances, the present inventors have found that a rapid high temperature processing can be performed, that the amount of the replenisher to be supplemented is low and that a stable development processing can be performed over a long time period of the order of not less than 3 months without exchanging the developer only when the developer having the foregoing composition is used.
The developers and replenishers for developer used in the invention are preferably aqueous solutions mainly composed of alkali metal silicates and alkali metal hydroxides represented by MOH or their oxyde, represented by M2O, wherein said developer comprises SiO2 and M2O in a molar ratio of 0.5 to 1.5 and a concentration of SiO2 of 0.5 to 5% by weight. As such alkali metal silicates, preferably used are, for instance, sodium silicate, potassium silicate, lithium silicate and sodium metasilicate. On the other hand, as such alkali metal hydroxides, preferred are sodium hydroxide, potassium hydroxide and lithium hydroxide.
The developers used in the invention may simultaneously contain other alkaline agents. Examples of such other alkaline agents include such inorganic alkaline agents as ammonium hydroxide, sodium tertiary phosphate, sodium secondary phosphate, potassium tertiary phosphate, potassium secondary phosphate, ammonium tertiary phosphate, ammonium secondary phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate and ammonium carbonate; and such organic alkaline agents as mono-, di- or triethanolamine, mono-, di- or trimethylamine, mono-, di- or triethylamine, mono- or di-isopropylamine, n-butylamine, mono-, di- or triisopropanolamine, ethyleneimine, ethylenediimine and tetramethylammonium hydroxide.
In the present invention, particularly important is the molar ratio in the developer of [SiO2]/[M2O], which is generally 0.6 to 1.5, preferably 0.7 to 1.3. This is because if the molar ratio is less than 0.6, great scattering of activity is observed, while if it exceeds 1.5, it becomes difficult to perform rapid development and the dissolving out or removal of the light-sensitive layer on non-image areas is liable to be incomplete. In addition, the concentration of SiO2 in the developer and replenisher preferably ranges from 1 to 4% by weight. Such limitation of the concentration of SiO2 makes it possible to stably provide lithographic printing plates having good finishing qualities even when a large amount of plates according to the invention are processed for a long time period.
In a particular preferred embodiment, an aqueous solution of an alkali metal silicate having a molar ratio [SiO2]/[M2O], which ranges from 1.0 to 1.5 and a concentration of SiO2 of 1 to 4% by weight is used as a developer. In such case, it is a matter of course that a replenisher having alkali strength equal to or more than that of the developer is employed. In order to decrease the amount of the replenisher to be supplied, it is advantageous that a molar ratio, [SiO2]/[M2O], of the replenisher is equal to or smaller than that of the developer, or that a concentration of SiO2 is high if the molar ratio of the developer is equal to that of the replenisher.
In the developers and the replenishers used in the invention, it is possible to simultaneously use organic solvents having solubility in water at 20xc2x0 C. of not more than 10% by weight according to need. Examples of such organic solvents are such carboxilic acid esters as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate and butyl levulinate; such ketones as ethyl butyl ketone, methyl isobutyl ketone and cyclohexanone; such alcohols as ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenylcarbinol, n-amyl alcohol and methylamyl alcohol; such alkyl-substituted aromatic hydrocarbons as xylene; and such halogenated hydrocarbons as methylene dichloride and monochlorobenzene. These organic solvents may be used alone or in combination. Particularly preferred is benzyl alcohol in the invention. These organic solvents are added to the developer or replenisher therefor generally in an amount of not more than 5% by weight and preferably not more than 4% by weight.
The developers and replenishers used in the present invention may simultaneously contain a surfactant for the purpose of improving developing properties thereof. Examples of such surfactants include salts of higher alcohol (C8xcx9cC22) sulfuric acid esters such as sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol sulfate, ammonium salt of lauryl alcohol sulfate, Teepol B-81 (trade mark, available from Shell Chemicals Co., Ltd.) and disodium alkyl sulfates; salts of aliphatic alcohol phosphoric acid esters such as sodium salt of cetyl alcohol phosphate; alkyl aryl sulfonic acid salts such as sodium salt of dodecylbenzene sulfonate, sodium salt of isopropylnaphthalene sulfonate, sodium salt of dinaphthalene disulfonate and sodium salt of metanitrobenzene sulfonate; sulfonic acid salts of alkylamides such as C17H33CON(CH3)CH2CH2SO3Na and sulfonic acid salts of dibasic aliphatic acid esters such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate. These surfactants may be used alone or in combination. Particularly preferred are sulfonic acid salts. These surfactants may be used in an amount of generally not more than 5% by weight and preferably not more than 3% by weight.
In order to enhance developing stability of the developers and replenishers used in the invention, the following compounds may simultaneously be used.
Examples of such compounds are neutral salts such as NaCl, KCl and KBr as disclosed in JN-A- 58- 75 152; chelating agents such as EDTA and NTA as disclosed in JN-A- 58- 190 952 (U.S. Pat. No. 4,469,776), complexes such as [Co(NH3)6]Cl3 as disclosed in JN-A- 59- 121 336 (U.S. Pat. No. 4,606,995); ionizable compounds of elements of the group IIa, IIIa or IIIb of the Periodic Table such as those disclosed in JN-A- 55- 25 100; anionic or amphoteric surfactants such as sodium alkyl naphthalene sulfonate and N-tetradecyl-N,N-dihydroxythyl betaine as disclosed in JN-A- 50- 51 324; tetramethyldecyne diol as disclosed in U.S. Pat. No. 4,374,920; non-ionic surfactants as disclosed in JN-A- 60- 213 943; cationic polymers such as methyl chloride quaternary products of p-dimethylaminomethyl polystyrene as disclosed in JN-A- 55- 95 946; amphoteric polyelectrolytes such as copolymer of vinylbenzyl trimethylammonium chloride and sodium acrylate as disclosed in JN-A- 56- 142 528; reducing inorganic salts such as sodium sulfite as disclosed in JN-A- 57- 192 952 (U.S. Pat. No. 4,467,027) and alkaline-soluble mercapto compounds or thioether compounds such as thiosalicylic acid, cysteine and thioglycolic acid; inorganic lithium compounds such as lithium chloride as disclosed in JN-A- 58- 59 444; organic lithium compounds such as lithium benzoate as disclosed in JN-A- 50 34 442;organometallic surfactants containing Si, Ti or the like as disclosed in JN-A- 59- 75 255; organoboron compounds as disclosed in JN-A- 59- 84 241 (U.S. Pat. No. 4,500,625); quaternary ammonium salts such as tetraalkylammonium oxides as disclosed in EP-A- 101 010; and bactericides such as sodium dehydroacetate as disclosed in JN-A- 63- 226 657. In the method for development processing of the present invention, any known means of supplementing a replenisher for developer may be employed. Examples of such methods preferably used are a method for intermittently or continuously supplementing a replenisher as a function of the amount of PS plates processed and time as disclosed in JN-A- 55- 115 039 (GB-A- 2 046 931), a method comprising disposing a sensor for detecting the degree of light-sensitive layer dissolved out in the middle portion of a developing zone and supplementing the replenisher in proportion to the detected degree of the light-sensitive layer dissolved out as disclosed in JN-A- 58- 95 349 (U.S. Pat. No. 4,537,496); a method comprising determining the impedance value of a developer and processing the detected impedance value by a computer to perform supplementation of a replenisher as disclosed in GB-A- 2 208 249.
The printing plate of the present invention can also be used in the printing process as a seamless sleeve printing plate. In this option the printing plate is soldered in a cylindrical form by means of a laser. This cylindrical printing plate which has as diameter the diameter of the print cylinder is slided on the print cylinder instead of applying in a classical way a classically formed printing plate. More details on sleeves are given in xe2x80x9cGrafisch Nieuwsxe2x80x9d ed. Keesing, 15, 1995, page 4 to 6.
After the development of an image-wise exposed imaging element with an aqueous alkaline solution and drying, the obtained plate can be used as a printing plate as such. However, to improve durability it is still possible to bake said plate at a temperature between 200xc2x0 C. and 300xc2x0 C. for a period of 30 seconds to 5 minutes. Also the imaging element can be subjected to an overall post-exposure to UV-radiation to harden the image in order to increase the run lenght of the printing plate.
The following examples illustrate the present invention without limiting it thereto. All parts and percentages are by weight unless otherwise specified.

Heat mode sensitive imaging element for making positive working printing plates


A cartridge type dental injection device capable of easily and quickly mounting or removing a cartridge loaded barrel in or from a socket therein and capable of altering orientations of a viewing window in the barrel and of a cut surface of a needle as desired.

This invention generally relates to cartridge-type dental injectors, and more particularly, to a mounting device for a barrel adapted to receive a cartridge therein.
In a manual type dental injection device, a cartridge receiving barrel is secured to a body of the injection device by fastening means such as a cramping screw. The barrel is also provided with diametrically opposite viewing windows formed therein and having a sufficient size to insert the cartridge into the barrel. In case of an electrically powered dental injection device, a cartridge receiving barrel is removably mounted in a socket defined by a mounting member which is connected to a support member for a plunger rod, the support member being secured to a nose portion of a housing of the injection device. The barrel is removed from the socket after completion of injection so that the cartridge can be inserted in the barrel, and the barrel is again mounted in the socket for injection. The barrel is provided with diametrically opposite viewing windows.
It is well known that the cartridge includes a rubber plug retained at the end of the cartridge by a metallic cap for sealing and adapted to be penetrated with an needle of a needle fitting when it is threadedly secured to the barrel at its forward end, and a plunger rubber fitted in a rear open end of the cartridge, and adapted to be pushed by the plunger rod, thereby ejecting the injection liquid contained in the cartridge, through the needle.
In the injection device of either type, the viewing windows play a important role in enabling a condition of the cartridge to be visibly ascertained, that is to say, enabling it to be determined how much injection liquid in the cartridge has been injected therefrom. The needle has at the tip end a cut surface to provide a sharp cutting edge thereto, and it is required that the gums be pierced with the sharp cutting edge with the cut surface facing the teeth of a patient.
As each dentist has a particular physique or posture for treatment to a patient, this results in an angle at which the dentist can best view the cartridge through the viewing window being changed. It is therefore required that a dentist alters an angular position of the viewing window in the barrel to one at which it is easy for the dentist to view the cartridge in the barrel through the viewing window, as well as the orientation of the cut surface defining the sharp cutting edge of the needle, against the teeth. In the case of manual type injector, the cramping screw is loosened relative to the injector body to enable the angular position of the barrel to be altered, but such manual operations for loosening and then tightening the cramping screw are troublesome and inefficient. In the case of the electrically powered dental injection device, it is impossible to alter the orientation of the viewing window so that it is oriented with the cut surface of the needle, because the barrel is installed in the socket at a fixed position. Since the barrel is arranged to enable it to be removed from the socket whenever it is to be loaded with the cartridge, there is a need for a simplified arrangement for installing the barrel in the socket.
It is an object of the invention to provide a cartridge type dental injection device capable of easily altering the orientations of the viewing window and of the cut surface of the needle as desired.
This object of the invention can be achieved by providing a device for mounting cartridge receiving barrel in a cartridge type dental injection device comprising a mounting member having a socket, a barrel adapted to be inserted in the socket and having diametrically opposite viewing windows formed therein, the mounting member having a plurality of circumferentially spaced apart ball retaining holes, and a locking ball placed in each of the holes, the barrel being provided with an annular groove adapted to receive a portion of each locking ball therein, and a locking ring having an annular cam surface and a relieving surface positioned adjacent to each other and movable between a position where when the locking balls are in alignment with the annular groove, the annular cam surface pushes the locking balls toward the annular groove to bring portions of the locking balls into engagement with the annular groove and a position where the relieving surface faces the locking balls to release them from the annular groove.
According to the invention, the movement of the locking ring from the position where the locking balls are released from the annular groove, may be in a direction toward or away from the housing of the injection device.
In the preferred embodiment of the invention, a coil spring may be provided for urging the locking ring to the position where the annular cam surface faces the locking balls.
Furthermore, there may be provided means for determining the position to which the barrel can be inserted in the socket. Such means may comprise a shoulder of the barrel, adapted to abut the forward end of the barrel.
The mounting member defining the socket may have a piece of rubber tightly fitted in an aperture drilled therein, the piece of rubber being in frictional engagement with a portion of the peripheral surface of the barrel to prevent it from unintentionally turning around it""s axis relative to the socket.
As the locking ring is manually pushed against action of the coil spring to the position where the relieving surface is opposite to the locking balls in the ball retaining holes, they are movable radially outwardly toward the relieving surface so that the barrel can be removed from or inserted in the socket for charge or removal of a cartridge, and when ceasing the pushing of the locking ring, it is returned to its original position under action of the coil spring so that the annular cam surface will engage the locking balls to push radially inwardly them into the annular groove, thereby preventing the barrel from coming out of the socket. In this position, the barrel is rotatable around it""s axis so as to be capable of altering the orientations of the viewing window and cut surface of the needle secured to the barrel as desired. The piece of rubber apples enough braking to the barrel by frictional engagement with the outer peripheral surface of the barrel, to prevent it from unintentionally turning, thereby, maintaining the desired orientations of the viewing window and cut surface of the needle during injection.

Barrel mounting device in cartridge-type dental injection device

Abstract: The cartridge type dental injection device comprises a barrel (9) adapted to be inserted in a socket (5) defined by a mounting member (5a) and having diametrically oppositee viewing windows (11) formed therein, the mounting member (5a) having a plurality of circumferentially spaced apart ball retaining holes (7), and a locking ball (8) placed in each of the holes, the barrel (9) being provided with an annular groove (12) adapted to receive a portion of each locking ball therein, and a locking ring (13) having an annular cam surface (14) and a relieving surface (15) positioned adjacent to each other and movable between a position where when the locking balls (8) are in alignment with the annular groove (12), the annular cam surface (14) pushes the locking balls (8) toward the annular groove (12) to bring portions of the locking balls into engagement with the annular groove and a position where the relieving surface (15) faces the locking balls (8) to release them from the annular groove (12).

deceasedby Kayoko Kawagishi, Masayuki Kawagishi,


A separator arrangement includes a separator having a drum with a vertical rotation axis. The drum is placed on a rotatable drive spindle and is surrounded by a shroud. A separating wall separates the separator arrangement into a sanitary area that includes the drum and the shroud and a drive area that includes the drive device. The separator and the drive device are decoupled as a unit, in terms of vibration, by at least one of the separating wall and a foundation attachment. The drive device includes a motor, a coupling, at least one bearing device, and a flange section around the drive spindle underneath a drive cover, and a sealing device. A membrane arrangement is formed in a region of the drive cover and, for vibration purposes, decouples the drive cover from the machine frame in a region around the drive spindle.

The present disclosure relates to a separator arrangement. The separator arrangement includes a separator having a drum with a vertical rotation axis. The drum is placed on a rotatable drive spindle and is surrounded by a shroud. The drum is rotatable during operation by a drive device at a rotation speed of more than 1000 rpm but less than 8500 rpm.
Separator arrangements such as these are known. WO 02/096 566 A1, for example, represents relevant prior art.
DE 43 42 471 C1 and DE 103 11 997 A1 relate to filter centrifuges. U.S. Pat. No. 5,343,282 discloses a laboratory centrifuge.
For various applications of separators, for example, in the field of medicine or foodstuffs, it is necessary to operate separators of a generic type as noted above so as to comply with particularly stringent sanitary and hygiene requirements.
The present disclosure relates to a separator arrangement which complies with these requirements using physically simple means.
The present disclosure relates to a separator arrangement including a separator having a drum with a vertical rotation axis. The drum is placed on a rotatable drive spindle and is surrounded by a shroud. The drum is configured to be rotated during operating by a drive device at a rotation speed of more than 1000 rpm, or more than 2500 rpm, but less than 8500 rpm. The separator arrangement includes a separating wall which separates the separator arrangement into a sanitary area including the drum and the shroud and into a drive area including a drive device. The separator, which includes a machine frame with the shroud and the drum, and the drive device are decoupled as a unit, in terms of vibration, by the separating wall and possibly a foundation attachment.
An arrangement of the components of the separator arrangement is selected such that work to be done on the drive device, such as work on a motor, coupling, spindle, bearing and other maintenance and repair work, can be carried out on the components of the drive device in the drive area without having to make any connection to the sanitary area.
As an example, this arrangement of components allows a lubricant change or motor replacement to be carried out in a simple manner. Conversely, it is possible to work on the shroud or the drum in the sanitary area without having to make any connection to the drive area.
In contrast to DE 36 22 886 A1 and JP 08-024714 A, which disclose centrifuges which are designed to remove fission products from dissolved core fuel, and in which the drive and the drum are separated from one another by a concrete cover, in order to shield the drive from radiation, the present disclosure advantageously provides for the entire separator, together with the machine frame, to be decoupled, in terms of vibration, by the separating wall. In addition, the drum can also advantageously be decoupled, in vibration terms, from the machine frame.
The sanitary area is arranged above the separating wall, and the drive area under the separating wall.
The present disclosure, for example, can be implemented in a simple manner by the sanitary area and the drive area being two areas of a building which are separated from one another and surrounded by the separating wall in the form of a ceiling.
The sanitary area is itself subdivided into a first sanitary region outside the shroud and a second sanitary region inside the shroud. It is, for example, generally sufficient for the first sanitary region outside the shroud to be subject to less stringent cleanliness requirements than the second sanitary region inside the shroud, which may even be in the form of a sterile region. In order to comply with such stringent cleanliness requirements, it is advantageous for the region around the shroud also to be designed to be sanitary, and not to allow any contamination from the drive area to enter the region or area around the shroud.
Vibration decoupling of the separating wall from the machine frame, with its walls, has an advantageous effect which can be achieved via sealing, flexible connecting elements such as a membrane.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.
The drive spindle 3 is mounted rotatably in a bearing housing 5 by one or more bearings 4. The bearing housing 5 is supported on an upper flange section 5a via elastic elements 6 on a machine frame 7.
The drive spindle 3 can be rotated with the aid of a motor 8 whose output-drive shaft 9 is arranged as an axial extension of the drive spindle 3. A coupling device 10 is arranged between the drive spindle 3 and the output-drive shaft 9 of the motor 8. The separator arrangement 1, according to the present disclosure, can be, for example, implemented advantageously in a compact form, as shown in the Drawing. The motor 8 is arranged entirely or partially under the machine frame 7. It is within the scope of the present disclosure, for example, to achieve a compact design, for the motor 8 to be arranged inside the machine frame 7, and for the motor 8 and the drum 2 to have a common bearing (not shown).
The drum 2 is surrounded by a shroud 11 which is connected in a firm and gas-tight manner to the machine frame 7 in a lower region 13 of shroud 11. It is within the scope of the present disclosure that a trap for solids can also be connected between the shroud 11 and the machine frame 7.
Overall, a sanitary region 25 within the shroud 11 is sealed in a gas-tight manner from another sanitary region 24 surrounding the shroud 11 and from a drive area 20. This makes it possible to design region 25 to be sanitary. Furthermore, the region 24 outside the shroud 11 is also designed to be gas-tight with respect to the drive area 20, under a separating wall 16, for which purpose suitable precautions must be taken.
A drive cover 23 is formed between the region 13 on which the shroud 11 is fixed to the machine frame 7 and the drive spindle 3. The drive cover 23 is sealed by a sealing device 12 with respect to the drive spindle 3. By way of example, this sealing device 12 may be in the form of a sliding-ring seal or a barrier chamber. The barrier chamber may have two seals which are at a distance from one another and between which a fluid such as a gas can be introduced, which may be a sterile gas. The gas pressure in the barrier chamber is then kept higher than in adjacent areas in the various operating states.
A membrane arrangement 21 is formed on the drive cover 23 between the sealing device 12 and the region 13 in which the shroud 11 is arranged on the machine frame 7. The membrane arrangement 21 decouples the machine frame 7, in terms of vibration, from the spindle 3 and the sealing device 12.
The entire separator, that is to say the machine frame 7 with the shroud 11 and the drum 2, together with drive device 22, is supported via at least one or more elastic supporting elements 14. The elastic supporting elements 14 have damping characteristics which act on a lower foundation attachment 15 of a separating wall 16. The separating wall 16 is shown as being in the form of a flat wall which separates, for example, a building area in which the separator is arranged into a sanitary area 19, which complies with the stringent sanitary requirement above the separating wall 16, and drive area 20 under the separating wall 16.
The sanitary area 19 and the drive area 20 may be, for example, two areas of a building which are separated from one another and surrounded by the separating wall 16 in the form of a ceiling.
Since the machine frame 7 is supported via elastic elements 14 on the lower foundation attachment 15 of the separating wall 16, it is advantageously decoupled, in terms of vibration, from the separating wall 16.
The sanitary area 19 is subdivided into first sanitary region 24 above the separating wall or ceiling 16 and outside the shroud 11, and into second sanitary region 25 inside the shroud 11 and above the drive cover 23. It is within the scope of the present disclosure for the second sanitary region 25 to be designed to be sterile, with the entire area inside the shroud 11 being designed such that it can be steam-sterilized. The temperatures used may be above 120° C., corresponding to a pressure of 1 bar (overpressure). Higher temperatures and pressures can also be provided, for example 134° C./2 bar, with the design of the separator arrangement 1 components being selected appropriately. This makes it possible to produce sterile regions or clean areas or very clean areas, corresponding to the normal specialist use of these terms.
A gap 17 is formed between the separating wall 16 and the machine frame 7 and gap 17 is closed by a elastic sealing element 18 in the form of a membrane. This is to allow relative movements between the separating wall 16 and the machine frame 7. The sealing element 18 closes the drive area 20 off from the sanitary area 19 in an air-tight manner, in such a way that no germs can pass through or dirt/contamination can enter the sanitary area 19.
All of the power and the oil supply from the drive or motor 8 is provided in the drive area 20 under the separating wall 16. Separator arrangement 1 is designed such that there is no need to make any connection between the sanitary area 19 and the drive area 20 even for maintenance tasks. The drum 2 and shroud 11 can therefore be removed on their own from the sanitary area 19. That is so because, according to an embodiment of the present disclosure, all the elements for fixing or working on selected components of separator arrangement 1 are accessible from the sanitary area 19.
The drive device 22 comprises the motor 8, the coupling 10, and the bearing device 4, as well as the lower region 13 of the drive spindle 3 below the sealing device 12. A region inside the machine frame 7 can form an actual drive region via which the bearing 4 is also lubricated.
The separator arrangement 1, as shown in the Drawing, complies with very stringent safety requirements. For example, in the field of medicine, the separator arrangement 1, according to the present disclosure, makes it possible to comply with clean-area or even very-clean-area conditions in region 24.
Although the present disclosure has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present disclosure is to be limited only by the terms of the appended claims.

Separator arrangement in sanitary design


A vehicle suspension system includes a fluid pump, a pair of suspension cylinders and a hydraulic control circuit for controlling pressurization of the suspension cylinders. Each suspension cylinder has a head end and a rod end. The control circuit includes a proportional rod pressure control valve with a first pilot which is exposed to a pressure which is communicated to the head end of the suspension cylinder, and a second pilot which is exposed to pressure which is communicated to the rod end of the suspension cylinder. The rod pressure control valve controls pressure in the rod end of the suspension cylinder as a function of and proportional to the pressure in the head end of the suspension cylinder. A suspension damping valve controls communication between a chamber of the cylinder and an accumulator.

The present invention relates to a suspension system for a vehicle, such as a heavy duty tractor.
Heavy duty tractors have been provided with front axle hydraulic suspension systems which include a pair of hydraulic cylinders connected between the frame and the axle of the tractor. One such system is described in German patent number DE 4242448, published Mar. 31, 1994. Such suspension systems also include hydraulic accumulators and can perform a chassis leveling function. Such tractors are subject to a wide range of axle loads, and these loads can exceed the normal pressure range of the accumulator. If an implement is attached to such a tractor, implement operation can produce large changes in load and chassis attitude which can interfere with implement control and with chassis attitude control. Leveling response time can be slow because flow to both the head and rod ends of the cylinders must be controlled by a pair of solenoid operated valves.
Such systems use a fixed pressure regulator to control rod side pressure or uses a common head and rod pressure. To achieve the maximum load range it is desirable to have a high rod pressure when the head pressure is low and a low rod pressure when the head pressure is high. To maintain level tractor attitude and better implement control it is desirable to restrict vertical chassis displacement when significant changes are anticipated. It is not desirable to block flow on both sides due to the potential to work head and rod against each other due to flow into the cylinder or thermal effects.
Such prior systems also do not allow for independent rod and head charging. As a result, flow typically goes to the rod side first, which is the path of least resistance. This results in delayed leveling operation, and results in the discharge of rod side oil that was just introduced into the rod side, thus wasting energy.
Accordingly, an object of this invention is to provide a hydraulic suspension control system which can accommodate a wide range of loads.
A further object of the invention is to provide such a system which avoids delayed leveling operation.
A further object of the invention is to provide such a system which does not waste energy by discharging rod side oil.
A further object of the invention is to provide such a system which maintains level tractor attitude and which improves implement control.
These and other objects are achieved by the present invention, wherein a hydraulic control circuit is provided for a vehicle suspension system having a fluid pump and suspension cylinders, each having a head end and a rod end. The control circuit includes a proportional rod pressure control valve with a pair of pilots. The first pilot is exposed to a pressure which is communicated to the rod end of the suspension cylinder. The second pilot is exposed to pressure which is communicated to the head end of the suspension cylinder. The rod pressure control valve controls pressure in the rod end of the suspension cylinder as a function of and proportional to the pressure in the head end of the suspension cylinder. System pressure is communicated to the rod pressure control valve via a solenoid operated raise/lower valve. In order to achieve the maximum load range, the system produces a high rod pressure when the head pressure is low and produces a low rod pressure when the head pressure is high.
Vertical chassis displacement is restricted to maintain level tractor attitude and provide better implement control by restricting flow between the cylinders and accumulator on one side of the suspension. Pilot pressure is applied to the damping valve rapidly to respond quickly to load changes. Flow between the cylinders and accumulator may be restricted or completely blocked. This results in a significant pressure differential between the cylinders and the accumulator. To control pressure equalization, pilot pressure is metered off across an orifice. The metering opens the damping valve slow enough so that the controller may respond to position changes by leveling, closing the pilot exhaust valve to hold the damping valve in position or reapplying pilot pressure to start the opening process again.
As an alternative to completely blocking flow between cylinders and accumulators, it is desirable to orifice flow between cylinders and accumulators. Gradual pressure equalization can easily be made up by leveling flow. When pressure is partially or completely taken care of by the equalization orifice, control requirements are simplified and the transition from damped to undamped operation is quick and seamless. The equalization orifice also improves safety by insuring that the cylinders and accumulators can be drained by the same elements, and insures equalization if the tractor is shut off while the suspension is in damped condition, thus avoiding unexpected motion if the damping valve opens at a later time.
The head and rod ends may be independently charged in order to achieve prompt leveling operation, and in order to avoid the discharge of rod side oil, thus saving energy. Flow can be applied to the head side first to accomplish a portion of the leveling before flow/pressure is applied to the rod side to set the rod side pressure. For this purpose, the head and rod side of the system are cross piloted.


A method and device for testing an electronic chip (10) having on the surface a plurality of addressable electrically conductive sensitive elements (12) in which the sensitive elements on the chip are put in contact with a conductive solution (52), one or more sensitive elements (12) are addressed selectively in order to apply to each sensitive element addressed an electrical test signal referred to as an input signal, and a signal, referred to as the output signal, on an electrode (60, 60a) also in contact with the conductive solution, is measured.

The present invention relates to a device and method for testing sensitive elements of the surface of an electronic chip.
More and more electronic chips are being used as an analysis support and/or an information collector in the fields of biological or chemical analysis, or for measuring physical quantities. The electronic chips have for this purpose on their surface a plurality of sensors, receivers or microsystems, hereinafter referred to as xe2x80x9csensitive elementsxe2x80x9d. The sensitive elements are, for example, electrodes which can be immersed in a fluid to be analyzed. These electrodes are then selectively covered with a lining layer sensitive to a given chemical or biological compound. In some cases, the chips can also have means for selectively addressing the sensitive elements in order to apply thereto an electrical potential or for making individual electrical measurements on these elements.
The present invention finds applications in particular in checking the correct functioning of electronic chips equipped with electrodes and in checking the quality of the sensitive lining layers which cover the electrodes.
The accompanying FIG. 1A is a schematic section of an electronic chip having electrodes.
The chip has a substrate 10 with a plurality of electrodes. For reasons of clarity only four electrodes are depicted in the figure, these electrodes bearing respectively the references 12a, 12b, 12c and 12d. A chip may, however, have a large number of electrodes. The electrodes have a bottom layer 13 made from a material such as titanium, for example, covered with a top layer 15 of a metal such as gold or platinum.
In order to confer on the electrodes their function of biological or chemical sensor, they are provided with a layer of reactive material or a material able to interact with the biological material. These materials may include electrically conductive polymers. By way of example, a modified polypyrrole can be used as a biologically sensitive layer.
All the electrodes can be covered with the same material or can be selectively covered with different materials sensitive to different compounds. By way of illustration of the use of chips equipped with electrodes, for the analysis of chemical or biological substances, reference can be made, for example, to documents (1) and (2) whose references are indicated at the end of the present description. Document (3), also referenced, relates more generally to the machining of silicon and the manufacture of sensors.
Returning to FIG. 1A, it can be seen that the electrodes 12 on the chip 10 are electrically connected to input/output terminals 14, only one of which is shown. The electrical connection is shown schematically by a dot and dash line 16.
Where the chip has a small number of electrodes, each electrode can be respectively connected to a particular input/output terminal associated with it.
However, as shown in FIG. 1A, the connection between the electrodes and the input/output terminals can also be effected by means of multiplexer circuits 18.
The multiplexer circuits enable addressing to take place from a small number of input/output terminals to several hundreds of electrodes on the surface of the chip.
In the sense of the present description, addressing means the putting of at least one electrode (or other sensitive element) in electrical connection with at least one input/output terminal. The addressing of an electrode makes it possible not only to apply a voltage or signal to it by means of one or more input/output terminals but also to make electrical measurements on this electrode.
To effect addressing, that is to say to select a certain number of electrodes, the input/output terminals are connected to external electronic control devices, not shown, for example by connection means 20, shown in outline.
In FIG. 1A, it can be seen that the top metal layer 15 of the electrode 12d has a porosity 23 able to allow a fluid to come into contact with the subjacent bottom layer 13 of the electrode.
Moreover, during the manufacture of the electrodes, residues of material may remain on the surface of the chip. For example, residues of lacquer used during operations of forming etching masks may remain.
Such residues, marked in FIG. 1A with the references 24a, 24c and 24d, may partly cover an electrode, which is the case with the electrode 12a, cover it completely, which is the case with the electrode 12c, or remain in a region with no electrodes, which is the case with the residue 24d.
As mentioned previously, the electrodes on a chip, intended for the analysis of biological or chemical environments, are covered with a layer of material which confers on them their sensitivity to a given chemical compound or biological substance.
The lining of the electrodes on the chip in FIG. 1A is illustrated by FIG. 1B. It can be seen that the electrode 12b in FIG. 1B is covered with a sensitive layer 22b, for example made of conductive polymer. The sensitive layer 22b covers the entire surface of the electrode. The sensitive layer can be formed by selective deposition methods or possibly electrochemically by selectively applying an appropriate electrolysis current to each electrode which is to be lined.
It can be seen, on the other hand, for the electrode 12a, that the material of the sensitive layer 22a covers only part of its surface not encumbered by the residue 24a. Thus the covering of the electrode 12a is not homogeneous.
For the electrode 12c, it can be seen that the residue 24c which covers the entire surface prevents the formation of a sensitive layer.
Finally, it is apparent that the electrode 12d in FIG. 1B has been partly destroyed during the lining step.
The bottom layer 13 of this electrode, by not being correctly protected by the top layer 15, because of the porosity 23, has undergone deterioration caused by the agents or fluids used for the lining of the electrodes. Thus the electrode 12d is unable to make analysis measurements.
Electrodes such as the electrode 12a or 12c which either have no sensitive layer or are equipped with a layer which only partially covers their surface, lead to erroneous analysis results.
Moreover, a residue such as the residue 24d, visible in FIGS. 1A and 1B, even if it does not directly interfere with the formation of a sensitive layer, risks interfering with the analysis measurements made on the adjacent electrodes.
All the probable faults mentioned above are liable to prevent the functioning or interfere with the functioning of a certain number of analysis electrodes on a chip.
Similar problems are posed also for chips equipped with other sensitive elements such as micromechanical elements, whose functioning may also be disturbed by residues of material or by defects caused during the manufacturing processes.
In the field of micro-electronics, a certain number of tests designed to check the correct functioning of electronic chips are known.
Amongst these tests there are notably conductimetry tests and visual tests.
Conductimetry tests consist essentially of moving movable conductive spikes on the surface of the chip in order to put them in contact with conductive elements on this chip and check the passage of a measuring current.
However, in an application to analysis chips, electrical tests with movable spikes do not make it possible to detect the electrodes which are certainly covered with a lining layer but for which the lining layer has a lack of homogeneity or porosities, or covers only part of the electrode, as in the case of the electrode 12a in FIG. 1B.
In addition, electrical tests with movable spikes offer a resolution which makes it difficult to use them for chips where the electrode pitch is less than 50 xcexcm.
In addition, the movable test spikes moved on the surface of the chip risk locally breaking a layer of residue covering an electrode and locally coming into contact with the subjacent electrode. In this case, a measuring current may be detected and the electrode is considered to be functional whilst it remains essentially covered by the layer of residue. Thus an electrode such as the electrode 12c in FIG. 1 would be wrongly considered to be valid.
In the same way, the movement of the movable test spikes on the surface of a chip may mechanically damage the electrode coating layer. The test is then destructive.
Finally, it should be added that the electrical tests on the chips by means of movable spikes prove to be too lengthy and therefore unsuitable for checking chips having numerous electrodes.
Visual tests, carried out by microscopy, are valid only when the coating layers to be checked have a certain thickness. When the electrode coating layer is formed by a very fine deposit, such as a monomolecular layer or a layer formed by adsorption of material on the electrodes, visual test methods prove unsatisfactory and unsuitable. This is the case notably for chips having analysis electrodes.
Finally, the usual known tests in the field of microelectronics prove unsuitable for checking analysis chips as described previously. In particular, these tests do not make it possible to correctly evaluate, qualitatively and quantitatively, the functioning of the electrodes.
The purpose of the present invention is to propose a test method for checking the correct functioning of a chip having sensitive elements, by means of a qualitative and quantitative check on the functioning of each sensitive element on the chip.
Another aim is to propose a test method not presenting the difficulties or limitations indicated above.
One aim is in particular to propose such a method able to be applied systematically to chips having addressable electrodes.
Another aim is to propose such a method which can be implemented before or after the formation of functional coatings on the electrodes and which allows not only the checking of the electrode addressing system but also, where applicable, the quality and homogeneity of the coating layers on them.
Another aim of the invention is to propose an inexpensive and non-destructive test method making it possible to automatically and individually test, if necessary, all the sensitive elements.
One aim of the invention is also to propose a simple and inexpensive test device intended for implementing the test method.
To achieve these aims, the object of the invention is more precisely a method of testing an electronic chip having on the surface a plurality of addressable conductive sensitive elements, in which the sensitive elements on the chip are put in contact with a conductive solution, in which one or more sensitive elements are selectively addressed in order to apply to each sensitive element addressed an electrical test signal referred to as the input signal, and a signal, referred to as the output signal, for example on a counter-electrode in contact with the conductive solution, is measured.
The conductive solution is, for example, an aqueous or organic solution sufficiently conductive to allow a measurable current to pass, and which will attack the substrate to be tested as little as possible, both during the electrochemical activation and at rest. It is possible to use, for example, water or a mixture of solvents optionally with substances such as salts added, reducing its electrical resistance.
Advantageously, the conductive solution can be a liquid identical or similar to a liquid which is subsequently to be analyzed or used for analysis.
By virtue of the method of the invention, no mechanical contact with the chip is necessary, and thus the risk of damage to the sensitive elements is removed. In addition, the method can be implemented automatically and rapidly even when the chip tested has a large number of electrodes.
According to a particular aspect of the invention, it is possible to test the sensitive elements, for example electrodes, either collectively or successively and individually.
By way of example, it is possible to carry out successive tests relating to a set of sensitive elements addressed, to which a sensitive element supplementary to each test is respectively added.
It is also possible to perform a test relating simultaneously to a plurality of sensitive elements on the chip or to all the sensitive elements on the chip.
According to a particular implementation of the method, the electrical test signal can simply be an electrical potential. Electrical potential means a difference in potential measured for example with respect to the counter-electrode.
When an electrical potential is applied to an electrode or to a sensitive (conductive) element, an electrical current is generated through the conductive solution as far as the counter-electrode. This measured current then constitutes an output signal. In the same way, when a potential is applied to several electrodes, the output signal comprises the sum of the currents generated in the conductive solution from each electrode addressed.
Optionally, the electrical potential applied to the electrodes can be adjusted with respect to a reference electrode also in contact with the conductive solution.
Another object of the invention is a device for testing addressable sensitive elements, such as the electrodes on an electronic chip. The device has:
an electrochemical cell containing a conductive solution, able to receive the addressable sensitive elements on the electronic chip,
means for selectively addressing at least one sensitive element and for applying thereto at least one signal, referred to as the input signal,
means, connected to at least one electrode in contact with the conductive solution, for measuring at least one signal, referred to as the output signal, in response to the input signal applied to at least one sensitive element on the electronic chip.
In the case where the chip has a plurality of electrodes, one or more of these electrodes can be used for measuring the output signal. A particular electrode, independent of the chip, can also be put in contact with the conductive solution in order to measure the output signal. In the remainder of the text, the electrode used for closing the circuit is designated as the counter-electrode.
The electrochemical cell can be formed by any device for putting the sensitive elements on the chip and the counter-electrode in contact with a conductive solution.
According to a particular embodiment, the electrochemical cell can include a vessel containing the conductive solution.
The counter-electrode can be separate from the chip and immersed in the conductive solution. It can also be formed directly on the chip and be put in contact with the conductive solution at the same time as the electrodes on the chip.
The means for selectively addressing the sensitive elements and applying an input signal thereto can include a power supply, capable of delivering a potential, and a system for addressing the electrodes for applying the said potential to one or more selected electrodes.
Other characteristics and advantages of the present invention will emerge more clearly from the following description, with reference to the figures in the accompanying drawings. This description is given purely as an illustration and non-limitatively.
In particular, the description which follows refers explicitly to the particular case in which the sensitive elements on the chip are electrodes for analysing chemical or biological substances.
To measure the output signal, the device can have a system for measuring a current generated in the electrochemical cell which passes through the counter-electrode, as a function of the number of sensitive elements addressed.
However, the invention is not limited to this application. This is because other more complex sensitive elements such as mechanical microsystems, accelerators or more generally elements having at least one addressable conductive armature, can be tested like the simple conductive electrodes.

Device and method for testing sensitive elements on an electronic chip