US3928669A

US3928669A - Image-forming method

Info

Publication number: US3928669A
Application number: US423800A
Authority: US
Inventors: Isoji Takahashi
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1972-12-12
Filing date: 1973-12-11
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: JPS4982344A; GB1449518A

Abstract

An image-forming method, which comprises positioning a grounded conductive pattern in contact with one side of an insulating sheet having on the opposite side a uniform, fine uneven surface of depressions and projections, forming, on the opposite surface of the insulating sheet, an electrostatic latent image in conformity with the conductive pattern by subjecting the surface to corona discharging, supplying toner particles thereto whereby the toner particles adhere only to the depressions in the surface corresponding to the latent image, and then transferring the toner particles to a receiving material by facing the surface to the receiving material.

Description

[4 1 Dec. 23, 1975 IMAGE-FORMING METHOD [75] Inventor: lsoji Takahashi, Asaka, Japan [73] Assignee: Fqii Photo Film Co., Ltd.,

Minami-ashigara, Japan 22 Filed: Dec.11,l973

2| App1.No.:423,800

[30] Foreign Application Priority Data f Dec. 12, 1972 Japan 47-124563 [52] US. Cl. 427/19; 427/24; lOl/DIG. 13 [51] Int. Cl. G036 13/08; 003G 13/22 [58] Field of Search 117/175; 96/] R, 1 SD,

96/1.4; 118/637; 355/3 R, 3 DD, 17; 101/D1G. 13; 427/14, 24, 19

3,561,358 2/1971 Weigl 96/1 R 3,585,061 6/1971 Allinger et a1 117/175 3.765.330 10/1973 Gundlach 101/010. 13 3,801,315 4/1974 Gundlach et a1. 96/1.4

Primary Examiner Michael Sofocleous Attorney, Agent, or Firm-Gera1d J. Ferguson, Jr.; Joseph J. Baker [57] ABSTRACT An image-forming method, which comprises positioning a grounded conductive pattern in contact with one side of an insulating sheet having on the opposite side a uniform, fine uneven surface of depressions and projections, forming, on the opposite surface of the insulating sheet, an electrostatic latent image in conformity with the conductive pattern by subjecting the surface to corona discharging, supplying toner particles thereto whereby the toner particles adhere only to the depressions in the surface corresponding to the latent image, and then transferring the toner particles to a receiving material by facing the surface to the receiving material.

12 Claims, 4 Drawing Figures US. Patent Dec. 23, 1975 Sheet 1 of2 3,928,669

FIG. 2

US. Patent Dec. 23, 1975 Sheet 2 of2 3,928,669

FIG. 3

FIG.4

IMAGE-FORMING METHOD BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to a method for form ing images and, more particularly, it relates to a method for forming images, which comprises electrostatically forming a powder image in conformity with a conductive pattern and transferring the powder image to a receiving material.

2. Description of the Prior Art Heretofore, a method for electrostatically forming a toner image, such as the method described in, e.g., U.S. Pat. No. 3,326,709, is known. In this known method, a conductive pattern is formed on the back side of an insulating sheet and, after connecting this conductive pattern to a ground, corona discharging is conducted from the surface side of the insulating sheet. Thus, corona ions adhere only to the area of the surface directly over the conductive pattern due to the difference in electrical capacity, forming an electrostatic latent image in conformity with the conductive pattern. Thereafter, this electrostatic latent image is developed according to a suitable known electrophotographic develping method.

When a toner image is formed according to the above-described method, the toner image formed projects above the surface of the insulating sheet. Therefore, when such a toner image is transfered to a receiving material, there is the possibility that, upon superposing the toner image-bearing insulating sheet and the receiving sheet one over one another, the toner image might be destroyed due to friction with the receiving material which is caused by possible sliding movement between the two. Accordingly, in the conventional image-forming method, the toner image-carrying insulating layer and the receiving material must be superposed one over one another so that no sliding movement therebetween occurs. When materials which are light in weight and are definite in size or surface area, such as paper, a resin film or the like, are used as the receiving material, the superposition of the insulating sheet and the receiving material one over the other can be mechanically effected with ease without causing any friction due to sliding. However, when materials which are heavy, such as an iron plate, or which are different in form, surface area or thickness are used as the receiving material, or when the insulating sheet and the receiving material are to be superposed over each other and the position adjusted, a superposing apparatus having an extremely complicated structure becomes necessary to satisfy all the above requirements. Such an apparatus, however, is quite expensive and the maintainance thereof is difficult. In actually, such an apparatus is impossible to make. As is described above, in the case of transferring toner images to receiving materials which are heavy, thick or different in form, surface area or thickness, or in the case of transferring after adjusting the position, the insulating sheet and the receiving material must be superposed one over the other manually with sufficient care. It is quite difficult to manually superpose the two over each other without causing any relative movement of a sliding nature. In particular, in the case of superposing an insulating sheet and a receiving material having a large surface area, or in the case of superposing the two while adjusting the position, manual operation becomes so difficult that there is a great possiblility that the powder image adhering to the insulating sheet and projecting will be rubbed against the surface of the receiving material, resulting in a damage of the image.

The present invention provides an image-forming method in which the possibility of the damage of the image due to the friction between the toner image and the receiving material is reduced even when a relative sliding movement is produced upon superposing the toner image-carrying sheet and the receiving material one over the other.

SUMMARY OF THE INVENTION The present invention comprises forming an unevenness on the surface of an insulating sheet having a conductive pattern on the opposite side, conducting corona discharging from the back side of the insulating sheet while connecting the conductive pattern to a ground, then forming an electrostatic latent image in the depressions of the surface of the insulating sheet in conformity with the conductive pattern, and adhering toner particles only to the depressions of the surface of said insulating sheet to form a toner image in conformity with said pattern.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIGS. 1 and 2 are cross sectional views showing one embodiment of the present invention.

FIGS. 3 and 4 are cross sectional views showing another embodiments of the present invention.

In these Figures, numerals 1 and l designate insulating sheets having an uneven surface, numeral 2 a con' ductive pattern, numeral 3 a corona charging element, numeral 4 a high voltage D.C. electric source, numeral 8 a receiving material and numeral 21 a light-sensitive material.

DETAILED DESCRIPTION OF THE INVENTION According to this method, the toner image will not be destroyed since the toner image is barely rubbed by the receiving material even when a relative movement between the insulating sheet and the receiving material is produced in a direction parallel to the sheets upon transferring the image by superposing the toner imagecarrying insulating sheet and the receiving material one over the other.

The present invention will now be described in detail by reference to the drawings. FIGS. 1 and 2 are cross sectional views showing an embodiment of the present invention. In FIG. 1, numeral 1 denotes an insulating sheet having a conductive pattern 2 on the back side thereof and unevenness on the opposite surface. Numeral 3 denotes a corona charging element which is connected to a direct current high voltage electric source 4. The conductive pattern 2 is connected to a ground through a suitable means. The insulating sheet I is made ofa highly insulating resin film of about 50 to 500 microns in thickness. For example, polyvinyl chloride, polyethylene, polypropylene, cellulose triacetate, a polyester, a fluorine-containing resin, etc. can be used.

The conductive pattern 2 can be formed, for example, by applying a conductive ink to the back side of the insulating sheet 1, a pattern-like metal deposition layer, a plated metal layer, etc. Also, a conductive pattern prepared by bringing a patternlike metal mass into contact with the back side of the insulating sheet I can be used.

The unevenness on the surface of the insulating sheet 1 can be formed by, e.g., sound mat processing, chemical mat processing, or by bringing a rough-surfaced hot roller into contact therewith. Furthermore, the unevenness can be formed by applying particles of a size of 5 to 200 microns to the surface of the insulating sheet 1 together with a binder; by insulation-processing an embossed paper; or by any optional known methods.

The depth of the depressions, i.e., from the top of the projections forming the depressions, must be about 5 to 200 microns since it is necessary for the toner particles to get thereinto. The sizes of the depressions and the projections will vary depending upon the purpose for use. However, it is sufficient for them to be small enough with respect to the picture element to be reprodueed.

When the corona charging element 3 is moved in the direction shown by the arrow 5, the generated corona ions selectively adhere only to the area of the surface of the insulating sheet 1 directly over the conductive pattern 2. By suitably selecting the voltage of the direct current high voltage electric source, corona ions can selectively be adhered to the bottom of the depressions as shown by positive signs 6. This phenomenon occurs since the difference in thickness due to the unevenness on the support of the insulating layer 1 produces a difference in the electrostatic capacity between the depressions and the projections, which results in the corona ions gathering in the depressions having a larger electrostatic capacity. Suitable corona generating devices are disclosed in US. Pat. No. 2,588,699.

Thus, an electrostatic latent image in conformity with the conductive pattern is formed in the depressions on the surface of the insulating sheet 1. This electrostatic latent image can be developed using known electrophotographic developing methods such as a cascade method as disclosed in US. Pat. No. 3,618,55 l, a magnetic brush method as disclosed in US. Pat. No. 2,786,440, a powder cloud method as disclosed in US. Pat. No. 2,725,304, a fur brush method as disclosed in US. Pat. No. 2,902,974 or the like.

When the charge of the toner particles contained in a developer is of the opposite polarity to that of the electrostatic latent image, the toner particles are attracted by the electrostatic latent image and adhere to the depressions. Thus, a toner image is formed.

In FIG. 2, the insulating sheet 1 carrying the thus formed toner image 7 is superposed on the receiving material 8. On superposition, since the toner image 7 is formed on the depressions of the surface of the insulating sheet 1, the toner image is not destroyed even when a relative sliding movement is produced between the insulating sheet 1 and the receiving material 8.

Suitable examples of the receiving material 8 are conductive materials such as metals and alloys (e.g., iron, copper, aluminum, brass, etc. insulating materials such as paper and resin films, composite materials wherein a conductive layer and an insulating layer are integrated, and the like. When the receiving material contains a conductive portion, the conductive portion is grounded, while when an insulating material is used, it is placed on a grounded conductive base plate. FIG. 2 shows the case where a conductive material is used as the receiving material 8.

The following methods are effective to adhere toner particles only to the depressions of the surface of the insulating sheet:

i. Corona discharging conditions are suitably selected so that more charges are generated in the depressions utilizing the fact that the depressions are larger than the projections in electrical capacity. A suitable resistance is a resistance of more than l0 Q/cm", preferably [0 Q/cm ii. Only the depressions on the receiving material side are made insulating and the projections are made comparatively low in resistance. However, the resistance of the projections should be sufficiently high, since too low a resistance of the projections would make it difficult to generate charges in the depressions. To be specific, the resistance of the projections should be more than 10'" Q/cm preferably about 10 to l0" ohm/cm? iii. Toner particles are initially adhered to both the depressions and the projections. The resistance should be more than 10 fl/cm' preferably than l0 .Q/cm Then, the toner particles adhered on the projections are removed e.g., using a doctor blade.

After the formation of electrostatic latent image, the conductive pattern 2, provided on the surface of the insulating sheet 1, is electrically disconnected from the ground or is removed.

Then, the assembly of the insulating sheet 1 and the receiving material 8 is subjected to corona discharging from the back side of the insulating sheet by moving, in the direction shown by the arrow 9, a corona charging element 3 to which an electric potential of the same polarity as that of the toner particles is applied. The corona ions induced electrostatically repell the toner image 7 to transfer it to the back side of the receiving material 8. In this occasion, where the conductive pattern 2 remains on the back side of the insulating sheet I, an electric potential can be applied between the conductive pattern 2 and the conductive portion of the conductive material 8 so as to shift the toner image to the receiving material 8.

The toner image, thus transferred to the receiving material 8, can be fixed according to known electrophotographic fixing methods using heat or solvents.

This embodiment was conducted as follows.

One side of a I00 u-thick polyester resin (a polyethylene terephthalate film, made by Toray Industries, Inc.) was sound mat processed to provide a substantially uniform unevenness of about 20 microns in depth. Then, a conductive pattern was manually drawn on the opposite smooth side using a conductive paint (Dotite Paint, made by Fujikura Kasei Co., Ltd, containing approximately silver powder 30% by weight, epoxy resin binder l% by weight and an amine group containing compound). This conductive pattern was connected to a ground, and corona discharging was conducted from the uneven surface side of the polyester resin using a corona charging element connected to a high voltage direct current electric source of-Ha KV. Then, the uneven surface side was subjected to development processing using a copier cascade developer (Model 9 l4, made by Fuji Xerox Co., Ltd.). Thus, toner particles were adhered to the depressions of the surface corresponding to the conductive pattern. This polyester resin carrying toner particles was then superposed on a 5 mm-thick iron plate with the toner image facing the iron plate. During this superposition the toner image was not destroyed even when a relative sliding movement was produced between the polyester resin and the iron plate. Thereafter, the iron plate was connected to a ground. Upon conducting corona discharging from the smooth surface side of the polyester resin using a corona charging element connected to a high voltage D.C. electric source of 8 KV, the toner particles were transferred and adhered to the iron plate. When this toner image-carrying iron plate was exposed to a trichlene solvent vapor, the toner image was fixed.

FIG. 3 is a cross sectional view showing another embodiment of the present invention.

In FIG. 3, numeral 21 designates a light-sensitive material which undergoes a change in conductivity upon exposure to light. Numeral 22 designates a photoconductive insulating layer of the light-sensitive material 21. As the photoconductive insulating layer, there can be used, e.g., a layer prepared by dispersing a photoconductive powder such as S, ZnS, ZnO, CdS, PbCl or TiO in a binder such as a silicone resin, an alkyd resin, an acryl resin, an epoxy resin, etc. an amorphous Se layer, ZnO layer etc. an organic photoconductive layer, such as N-vinyl carbozole, anthracene, polyvinylcarbazole, phthalocyanine etc. Numeral 23 is a conductive layer of the light-sensitive material 21. As this conductive layer, a light-transmitting material, such as a thin film of a metal (e.g., Ag, Cu, Al, etc.), a CuI layer or a 100 p. polyethylene terephthalate film (such as Luminar trade name produced by Toray Industries Co., Ltd.) having thereon a CuI layer and having thereon a layer of zinc oxide in a silicone resin such as Kr 2] I (trade name produced by Shin-etsu Chem. Co., Ltd.) can be used. Numeral 24 designates a support which must be transparent or semi-transparent. Suit able such supports, are e.g., a paper, a resin film, etc. Where a paper rendered conductive is used as the support 24, the conductive layer 23 is not necessary.

The thus constituted light-sensitive material 21 is superposed. in the same manner as in the aforesaid embodiment, on the back side of the insulating sheet 1 having an uneven surface on the opposite side while connecting the conductive layer 23 to a ground. Then, corona discharging is conducted from the uneven surface side of the insulating sheet by moving a corona charging element 3 in the direction shown by the arrow 5 while exposing the light-sensitive material 21 from the side of the support 24 to a light image. In this occasion, corona discharging can, of course, be conducted after exposure.

Corona ions, generated by means of the corona charging element 3, adhere to the area of the surface of the insulating sheet I which corresponds to the conductive area 25 in the photoconductive insulating layer 22, this conductive area 25 being rendered conductive by irradiation with light, thus forming an electrostatic latent image. At this point, these corona ions can be selectively adhered to the depressions by suitably selecting the voltage of the high voltage D.C. electric source 4 and the exposure amount.

Thereafter, the insulating sheet 1 and the light-sensL tive material 21 are separated from each other and, upon supplying toner particles in the same manner as described in the embodiment shown in FIGS. 1 and 2 to develop the electrostatic latent image 6, the toner particles adhere only to the depressions. The thus formed toner image cannot be destroyed even when a relative sliding movement is produced between the receiving material and the insulating sheet upon superposing the two one over the other, since the toner image is formed in the depressions of the surface of the insulating sheet I. In this embodiment, imagewise irradiation is conducted after superposing the light-sensitive material on the insulating sheet. However, when a light-sensitive material containing a photoconductive insulating layer whose conductivity lasts imagewise irradiation (e.g., those materials having a conductivity of IO Qcm in dark and 10"" .Qcm after exposure) is used, such a light-sensitive material can be exposed in advance prior to superposing on the insulating sheet. In this case, the conductive layer and the support can be opaque since the exposure can be conducted from the side of the photoconductive insulating layer. In addition, although imagewise irradiation is conducted in this embodiment from the side of the support of the light-sensitive material, the imagewise irradiation can be conducted from the side of the insulating sheet if the insulating sheet is transparent or semi-transparent. In such case, the conductive layer and the support of the lightsensitive material can be opaque.

FIG. 4 shows a further embodiment of the present invention, wherein numeral 1' designates as embossed paper, prepared by incorporating a highly insulating silicone resin such as KR 2l I trade name of a methyl phenyl polysiloxane produced by Shin-etsu Chem. Co., Ltd. in a paper provided with uneven pattern by embossing, which functions as an insulating sheet. Such an embossed paper, can be, e.g., a paper about 150 athick wherein the embossing cycle is 600 Mprojection: 250 pr, depression: 350 p.) and the depth of the embossing is about [.L, the embossment being formed on the back side 1' a of the paper. On the opposite surface 1'!) of the embossed paper, a slightly less embossed pattern remains.

A conductive pattern 2' is drawn on the back side I of this embossed paper using a conductive ink. Then, a toner image 7' is formed in the same manner as in the embodiment shown in FIGS. 1 and 2. Thus, the toner image 7' is formed on both the projections and the depressions of the surface lu of the embossed paper 1' in conformity with the pattern. The toner image can be formed only on the depressions by removing the toner particles adhering to the projections using a doctor blade.

With this embodiment, the present invention can be practiced by transferring and fixing the thus formed toner image in the same manner as in the aforesaid embodiments.

In the above explanation, corona charging is conducted by inducing positive corona ions. However, the present invention can of course be practiced by inducing negative ions.

As is described above, according to the present invention, toner images are not destroyed even when a relative sliding movement is generated between the insulating sheet and the receiving material. Therefore, the present invention is useful particularly in the case where aforesaid relative movement cannot be avoided because of the manual work of superposing a heavy or thick receiving material or of superposing various receiving materials different in form, surface area or thickness to transfer images.

Further, where the superposing is mechanical, the present invention is very effective, because destruction of toner image due to the friction between the insulating sheet and the receiving material can be completely avoided.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

1. An image-forming method, which comprises positioning a grounded conductive pattern in contact with the back side of an insulating sheet having on the front side a uniform, fine uneven surface of depressions and projections, the depth of said depressions being about to 200 microns,

forming, on said front surface of said insulating sheet,

an electrostatic latent image in conformity with said conductive pattern by subjecting said surface to corona discharging,

supplying toner particles thereto to deposit said toner particles only in the depressions in said front surface corresponding to the latent image, and

then transferring said deposited toner particles to a receiving material by facing said front surface to said receiving material, said receiving material tending to damage the developed latent image but being prevented from doing so since the toner particles are deposited only in the said depressions.

2. The image-forming method of claim 1, wherein said insulating sheet comprises an insulating resin film of polyvinyl chloride, polyethylene, polypropylene, cellulose triacetate, a polyester, or a fluorine-containing resin.

3. The image-forming method of claim 1, wherein said receiving material is a conductive material, an insulating material, or a composite material containing a conductive layer and an insulated layer.

4. The image-forming method of claim 1, including forming said electrostatic latent image by charging the depressions of said surface to a greater extent than the projections of said surface.

5. The image-forming method ofclaim I, wherein the depressions of said surface are electrically insulating areas and the projections of said surface are of low electrical resistance.

6. The image-forming method of claim 5, wherein said projections have a resistance of greater than 10" fl/cm 7. the image-forming method of claim 6, wherein ll projections have a resistance of greater than I cling/(1H2.

8. The image-forming method of claim 1, including supplying said toner particles to said surface and subsequently physically removing those toner particles from the projections of said surface so that said toner particles adhere only to and are only deposited in the depressions of said surface.

9. The image-forming method of claim 1 wherein said electrostatic latent image is formed by applying a conductive ink to the back side of said insulating sheet and simultaneously subjecting said front surface to said corona discharging.

10. The image-forming method of claim I wherein said electrostatic latent image is formed by applying a pattern-like metal deposition layer to the back side of said insulating sheet and simultaneously subjecting said front surface to said corona discharging.

11. The image-forming method of claim I wherein said electrostatic latent image is formed by plating a metal layer in the form of an image on the back side of said insulating layer and simultaneously subjecting said front surface to said corona discharging.

12. The image-fon'ning method of claim 1 wherein said electrostatic latent image is formed by contacting a pattern-like metal mass with the back side of said insulating sheet and simultaneously subjecting said front surface to said corona discharging.

Claims

1. AN IMAGE-FORMING METHOD, WHICH COMPRISES POSITIONING A GROUNDED CONDUCTIVE PATTERN IN CONTACT WITH THE BACK SIDE OF AN INSULATING SHEET HAVING ON THE FRONT SIDE A UNIFORM, FINE UNEVEN SURFACE OF DEPRESSIONS AND PROJECTIONS, THE DEPTH OF SAID DEPRESSIONS BEING ABOUT 5 TO 200 MICRONS, FORMING, ON SAID FRONT SURFACE OF SAID INSULATING SHEET, AN ELECTROSTATIC LATENT IMAGE IN CONFORMITY WITH SAID CONDUCTIVE PATTERN BY SUBJECTING SAID SURFACE TO CORONA DISCHARING, SUPPLYING TONER PARTICLES THERETO TO DEPOSIT SAID TONER PARTICLES ONLY IN THE DEPRESSIONS IN SAID FRONT SURFACE CORRESPONDING TO THE LATENT IMAGE, AND THEN TRANSFERRING SAID DEPOSITED TONER PARTICLES TO A RECEIVING MATERIAL BY FACING SAID FRONT SURFACE TO SAID RECEIVING MATERIAL, SAID RECEIVING MATERIAL TENDING TO DAMAGE THE DEVELOPED LATENT IMAGE BUT BEING PREVENTED FROM DOING SO SINCE THE TONER PARTICLES ARE DEPOSITED ONLY IN THE SAID DEPRESSIONS.

5. The image-forming method of claim 1, wherein the depressions of said surface are electrically insulating areas and the projections of said surface are of low electrical resistance.

6. The image-forming method of claim 5, wherein said projections have a resistance of greater than 1010 Omega /cm2.

7. the image-forming method of claim 6, wherein 11 projections have a resistance of greater than 1011 Omega Omega /cm2.

10. The image-forming method of claim 1 wherein said electrostatic latent image is formed by applying a pattern-like metal deposition layer to the back side of said insulating sheet and simultaneously subjecting said front surface to said corona discharging.

11. The image-forming method of claim 1 wherein said electrostatic latent image is formed by plating a metal 11in the form of a image on the back side of said insulating layer and simultaneously subjecting said front surface to said corona discharging.

12. The image-forming method of claim 1 wherein said electrostatic latent image is formed by contacting a pattern-like metal mass with the back side of said insulating sheet and simultaneously subjecting said front surface to said corona discharging.