JPH04296852A - Image forming method - Google Patents

Abstract

PURPOSE:To permit powder to exist at an image part with the superior contrast and permit the writing on a white part by selectively removing the developer on a light exposed part from a photosensitive sheet to a photoconductor and copying the residual developer to an image receiving paper. CONSTITUTION:A developer 17 which is previously electrified is loaded on a carrying roller 13 which is set oppositely to an electrode roller 12. The developer 17 is attracted to the electrode roller 12 by the electric field formed between the electrode roller 12 and the carrying roller 13, and the developer 17 is applied uniformly on a photosensitive sheet 11. When a photoconductor drum 23 is exposed through the photosensitive sheet 11 on which the developer 17 is applied, the polarity of an electric power source 21 is set so that the electric charge having the same polarity to the electrification polarity of the developer 17 is generated. Accordingly, a chemical latent image is formed on the photosensitive sheet 11, and the developer 17 on the white part of an original, i.e., the part where reflection light is obtained, is copied on the photoconductor drum 23 from the photosensitive sheet 11 and removed. The developer 17 is recovered by a cleaning unit 67.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an image forming method, in particular, a photosensitive pressure sensitive medium carrying microcapsules, and a powder that contributes to the color development of an image in cooperation with the contents of the microcapsules. It relates to a method of forming an image on paper.

0002

[Prior Art] Conventionally, a photosensitive pressure-sensitive medium (hereinafter referred to as a photosensitive sheet) carrying microcapsules containing a dye precursor and forming a chemical latent image whose mechanical strength changes in response to light has been used. , an apparatus that forms an image by applying a color developer to plain paper only to the image area using a color developer which is a powder that contributes to the formation of an image together with the contents of the microcapsules. This is proposed in Japanese Unexamined Patent Publication No. 2-137861.

FIG. 6 shows an embodiment of the device disclosed in this publication.
Explain with reference to. Inside the copying device 100,
A photosensitive sheet 11 carrying microcapsules is mounted on a photosensitive drum 108 charged by a charging corotron 120.
3 are stacked. The exposure device 109 forms an image of reflected light from the original on the surface of the photoreceptor drum 108 , forming an electrostatic latent image on the photoreceptor drum 108 and, at the same time, forming a chemical latent image on the photoreceptor sheet 113 .

[0004] Next, by developing the electrostatic latent image with a color developer 117, the color developer 117 is applied to the unexposed portions of the photosensitive sheet 113. The photosensitive sheet 113 coated with the color developer in this manner and the image receiving paper 121 which is plain paper are superimposed and pressure development is performed.
An image is formed on 21. According to this image forming method, since the color developer is not transferred to the portion of the image receiving paper 121 that corresponds to the white background portion of the document, it is possible to write on that portion with a pencil or the like, and it can be used as plain paper. Since the texture is maintained and the color developer is present in only the necessary minimum amount, there is an advantage that the image receiving paper does not curl due to heat shrinkage of the color developer.

[0005]

However, the surface resistance of the photosensitive sheet used in this device is three to four orders of magnitude lower than that of a so-called insulating film. This is because the electrical resistance of microcapsules is low. Therefore, even if an electrostatic latent image is formed on the photoreceptor, the distribution of charges induced on the photoreceptor becomes gentle when the photoreceptor is passed through the photoreceptor. It was impossible to obtain contrast. For this reason, the contrast of the color developer applied to the photosensitive sheet is disrupted, and the image on plain paper becomes unclear, resulting in insufficient color developer in the image area, or color developer being applied to the white area where there is no image. There was a problem of existence.

The present invention has been made in order to solve the above-mentioned problems, and provides an image forming method that is capable of forming an image on image-receiving paper so that a color developer is present only in the image area. The purpose is to provide a method.

[0007]

[Means for Solving the Problems] In order to achieve this object, the image forming method of the present invention provides a method of forming an image on the microcapsule-supporting surface of a photosensitive sheet, which contributes to the color development of an image in cooperation with the inclusions of the microcapsules. a powder coating step in which the powder is charged and uniformly applied; a charging step in which the surface of the photoreceptor is charged with the same polarity as that of the powder; a photosensitive sheet coated with the powder; A facing step in which charged photoreceptors are faced to each other with a predetermined gap, and the opposed photoreceptor sheet and photoreceptor are exposed to light to form a chemical latent image on the photoreceptor sheet, and the powder is selectively removed from the photoreceptor sheet. and an exposure removal step.

[0008]

[Function] In the image forming method of the present invention having the above-mentioned configuration, the charged powder is uniformly applied to the capsule supporting surface of the photosensitive sheet in the powder coating step, and separately from this, the charged powder is applied to the capsule supporting surface of the photosensitive sheet in the charging step. A charge of the same polarity as that of the powder is uniformly applied to the surface of the powder. Then, by the opposite process,
a capsule-supporting surface of the photosensitive sheet coated with the powder;
Charge retaining surfaces of the charged photoreceptor are opposed to each other. Next, when image exposure is performed in the exposure removal process, a chemical latent image is formed that hardens the capsules in the exposed areas of the photosensitive sheet, and the light that passes through the photosensitive sheet and powder causes the charge retention surface of the photoreceptor to is also exposed. Therefore, when the charge on the exposed charge-retaining surface disappears, there is no electrostatic repulsion between the photoreceptor and the charged powder on the photosensitive sheet facing the charge-retaining surface, causing the mirror image to disappear. The force causes the powder to adhere to the photoreceptor. In other words, the powder only in the exposed area is
It is selectively removed from the photosensitive sheet and transferred to the photoreceptor.

[0009] Thereafter, the photosensitive sheet is superimposed on an image receiving paper, which is plain paper, and pressure development is performed to form an image on the image receiving paper. In this way, an image-receiving paper is obtained in which powder is not present in areas other than the image, so-called white areas of the original.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In this example, the present invention is applied to an apparatus for forming a full-color image using microcapsules containing a dye precursor and a color developer, which is a powder that reacts with the dye precursor to form a color. It was applied.

First, in implementing the powder coating process, that is, the color developer coating process, a color developer coating apparatus 1 shown in FIG.
A color developer was applied to a photosensitive sheet cut into approximately A4 size. This device is the same as that already disclosed in Japanese Utility Model Application Publication No. 2-90838. A powdered color developer 17 is charged and supported on the support roller 13 . A support 11 is installed on the electrode roller 12 via a conveyor belt 18 . Further, an electric field is formed in the space between the electrode roller 12 and the support roller 13 by a power source 19. The color developer 17 supported on the support roller 13 receives an attractive force toward the electrode roller 12 due to this electric field, so that the color developer 17 is applied to the support 11. This time, a photosensitive sheet in which microcapsules are coated on a transparent polyethylene terephthalate (PET) film with a thickness of 25 μm was used as the support 11, and the space between the electrode roller 12 and the support roller 13 was applied at 2 to 3 kV/m.
An electric field of m was formed by a power source 19, and a developer 17 charged with - (minus) polarity was uniformly applied to the photosensitive sheet.

Next, the charging process was performed as shown in FIG. A so-called sheet-like OPC photoreceptor 23 having a transparent film coated with a transparent electrode and a photoconductive organic substance was placed on a grounded base 24, and the transparent electrode and the base were electrically connected. A corotron 22 is installed above the photoreceptor 23 so as to be movable with respect to the photoreceptor 23,
A voltage 21 of -6 kV was applied to uniformly give a charge 25 of (-) polarity to the surface of the photoreceptor 23. Photoreceptor 2 at this time
The surface potential of No. 3 was approximately -600V.

Next, the facing process was performed as shown in FIG. An original 31 such as a color photograph is placed on a glass plate 32, and the photosensitive sheet 11 is further coated with a color developer 1.
I installed it so that 7b was on top. Furthermore, photosensitive sheet 1
The photoreceptor 23 was placed above the photosensitive sheet 11 so as to face the photosensitive sheet 11 with the charge 25 facing downward. At this time, a spacer 37 was provided so that the photosensitive sheet 11 and the photoreceptor 23 faced each other with a gap of 0.3 to 1 mm. Further, below the glass plate 32, an exposure light source 35 consisting of a halogen lamp 33 is provided so as to be movable in the left-right direction in the figure by a guide rail 36. 34 is a reflecting plate. Here, both the charge polarity of the color developer 17b on the surface of the photosensitive sheet 11 and the polarity of the charge 25 on the photoreceptor 23 are (-
), the developer 17 and the photoreceptor 23 repel each other, and the developer 17 remains supported on the photoreceptor sheet 11.

Next, the latent image forming process will be explained with reference to FIG. After turning on the exposure light source 35, the guide rail 36
By moving the light source 35 in the left-right direction in the figure, the photosensitive sheet 11 is exposed to light from the back side of the document 31. That is, the light transmitted through the white background portion 31 a of the original hardens the capsules (not shown) of the photosensitive sheet 11 and passes through the color developer layer 17 to reach the photoreceptor 23 . Since the conductive layer of the photoreceptor 23 is grounded, the charge 25 on the exposed portion of the photoreceptor 23 disappears, and the surface potential drops to approximately 0V. Therefore, an image force acts between the (-) polarized color developer 17 and the photoreceptor surface 23, and the color developer leaves the photosensitive sheet 11 and adheres to the photoreceptor 23.

In the image portion 31b of the original, since light cannot pass through the original, the capsules of the photosensitive sheet 11 are not hardened, and the charge 25 on the photoreceptor 23 is not changed. Therefore, the color developer 17 in this portion remains on the photosensitive sheet 11. In this way, a state was obtained in which the capsules were not hardened and the color developer 17 remained applied only to the portion of the photosensitive sheet 11 corresponding to the image portion 31b of the original.

The photosensitive sheet thus obtained was placed on a plain image receiving paper and subjected to pressure development. The device used for pressure development is the same as the pressure development device of the image recording apparatus disclosed in Japanese Utility Model Application Publication No. 2-90838, and will therefore be omitted. After pressure development was performed, the photosensitive sheet and the image-receiving paper were peeled off to obtain an image on the image-receiving paper.

Next, the operation of an image forming apparatus embodying the image forming method of the present invention will be explained with reference to FIG. In the description, the same parts as used in the description of the image forming method described above are given the same reference numerals.

When the image forming apparatus 50 starts operating, the photosensitive sheet 11 is first fed out from the feeding cartridge 51 and conveyed to the electrode roller 12. Electrode roller 1
2 is connected to a power source 19. A pre-charged color developer 17 is supported on a support roller 13 facing the electrode roller 12 . This color developer 17 is
Due to the electric field formed between the electrode roller 12 and the support roller 13, an attractive force is applied in the direction of the electrode roller 12, so that the color developer 17 is uniformly applied to the photosensitive sheet 11. The above corresponds to the color developer application step. The photosensitive sheet 11 is further conveyed and reaches the photosensitive drum 23.

The surface of the photosensitive drum 23 is charged in advance by a corotron 22 to which a power source 21 is connected. This corresponds to the charging process described above.

At this point, the halogen lamp 33 is turned on, and the reflected light that passes through the slit 65 and the original table glass 32 and is reflected on the original 31 reaches the photosensitive drum 23. That is, the photosensitive drum 23 is exposed to light through the photosensitive sheet 11 coated with the color developer 17 . At this time, the polarity of the power source 21 is set so that a charge having the same polarity as the charging polarity of the color developer 17 is generated. Therefore, according to the principle explained earlier, a chemical latent image is formed on the photosensitive sheet 11, and the color developer 17 in the white background area of the document, that is, the area where the reflected light is obtained, is transferred from the photosensitive sheet 11 to the photosensitive drum. 23 and is removed. The color developer 17 transferred to the photosensitive drum 23 is recovered from the drum 23 by a cleaning unit 67. The above corresponds to the exposure and removal process.

The photosensitive sheet 11 is further provided with a developing unit 60.
will be transported towards. On the other hand, plain paper 61 serving as image-receiving paper is taken out from the stocker 62 and sent to the developing unit 60. In the developing unit 60, the photosensitive sheet 11 and the image receiving paper 61 are overlapped and pressed, and an image is developed on the image receiving paper 61. The image receiving paper 61 and the photosensitive sheet 11 are separated, and the photosensitive sheet 11 is collected into the take-up cartridge 52. An image is thermally fixed on the image receiving paper 61 by a fixing device 70, and the image is outputted to the outside of the apparatus.

The image forming method of the present invention described above can be implemented with partial modifications as follows. That is, the microcapsules of the photosensitive medium may contain colored dyes or pigments. in this case,
The powder that contributes to image formation includes dye absorbers and the like.

Furthermore, as a method for uniformly charging the photoreceptor in the charging process, instead of using a corona discharge such as a corotron or scorotron, a method is used in which a brush or roller connected to a power source is brought into contact with the photoreceptor. May be used. Further, in the exposure and removal step, the photosensitive sheet and the photoreceptor may be exposed to light using a semiconductor laser or the like. Further, in this embodiment, the photosensitive sheet is exposed from the back side, but the same effect can be obtained by exposing the photosensitive member first and transmitting the light to expose the photosensitive sheet. This method can be realized by providing an exposure light source such as a semiconductor laser inside the photosensitive drum shown in FIG.

[0025]

[Effects of the Invention] As is clear from the above explanation, according to the image forming method of the present invention, a chemical latent image is formed and a powder is transferred by a single exposure. , ensure that the area where the dye adheres and the area where the powder is present match. Furthermore, even if a photosensitive sheet with relatively low electrical resistance is used, powder is present only in the image area of the image receiving paper with good contrast. Therefore, it is possible to write on the blank area with a pencil or the like, the texture of the receiving paper itself is maintained, and curling caused by powder is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a powder coating step of the image forming method of the present invention.

FIG. 2 is a diagram showing a charging step of the image forming method of the present invention.

FIG. 3 is a diagram showing opposing steps of the image forming method of the present invention.

FIG. 4 is a diagram showing the exposure removal step of the image forming method of the present invention.

FIG. 5 is a diagram showing an image forming apparatus using the image forming method of the present invention.

FIG. 6 is a diagram showing a conventional image forming apparatus.

[Explanation of symbols]

10 Color developer coating device 11 Photosensitive sheet 12 Electrode roller 13 Support roller 17 Color developer 22 Corotron 23 Photoreceptor 25 Charge 31 Manuscript 32 Glass plate 35 Exposure light source 37 Spacer

Claims (1)

[Claims] 1. A microcapsule-supporting surface of a photosensitive pressure-sensitive medium whose mechanical strength changes in response to light is charged with powder that contributes to the formation of an image in cooperation with the contents of the microcapsules. a charging step of applying a charge of the same polarity as that of the powder to the surface of the photoreceptor; a photosensitive pressure-sensitive medium coated with the powder; and the charged photoreceptor. a facing step in which the photosensitive pressure sensitive medium and the photoreceptor are exposed to light to form a chemical latent image on the photosensitive pressure sensitive medium, and the powder is selectively exposed to the photosensitive pressure sensitive medium with a predetermined gap therebetween; An image forming method comprising an exposure removal step of removing the image.