JP4896523B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using electrophotography.

  In recent years, as digital cameras have become popular, the demand for direct photo printing by users themselves has increased rapidly. Inkjet printers met that expectation. Advances in the technology of inkjet printers have progressed rapidly, and today, image quality superior to silver halide photography has been achieved using special paper. However, there are problems such as light resistance and durability.

On the other hand, it is difficult to achieve photographic image quality with current electrophotographic printers. The first problem is the texture of the image surface such as gloss and smoothness. In the electrophotographic system, a toner having a particle size of 5 μm or more is placed on the surface of the paper, so that high gloss is difficult, and there is a problem that the difference in texture between the surface on which the toner is placed and the surface on which the toner is not worried. .
The second problem is image quality represented by an index called graininess. This is an index representing unevenness in image density, and the graininess of an electrophotographic image has been improved by reducing the particle size of toner, but it is still inferior to silver salt photography.

The digital camera print that Fuji Xerox installed at Seven-Eleven was commercialized overcoming the first issue, technically through the joint development of a cooling peel fixing device (MACS) and Fuji Photo Film. A dedicated media is used. Specifically, toner is embedded in a special paper whose surface is a thermoplastic resin by heat and pressure, and the toner is cooled while being in close contact with the high-gloss belt to copy the surface smoothness of the belt surface. . As a result, it achieves a high gloss and smooth surface quality equivalent to that of silver halide photographs, and has the same light resistance and durability as silver halide photographs.
However, the image quality represented by the graininess, which is the second problem, does not reach the silver salt photography level. In addition, a considerably large-scale device is required, and there will be many problems for general-purpose deployment.

  In addition, a method of laminating a printed image is well known, and it is commonly performed for an image output by an electrophotographic method, and a patent application regarding a laminate sheet for electrophotography has been made (for example, a patent). Reference 1). Many proposals have also been made regarding an electrophotographic image forming apparatus having a laminating function (for example, Patent Documents 2 to 7).

  However, these conventional techniques all require a large-scale device and are not practical. Furthermore, although high gloss can be obtained by the laminate method, this cannot be improved when the original image quality represented by the graininess is poor.

  In addition, a proposal for an image forming method in which a mirror image of an original image transferred and fixed on a transparent film is turned upside down and adhered to a blank sheet to obtain a high-gloss and high-quality image (Patent Document 8). ), But this proposal does not mention specific embodiments.

JP 2002-67504 A JP-A-62-161170 Japanese Patent Laid-Open No. 62-182781 JP-A-63-6684 JP 63-6585 A JP-A-9-150456 Japanese Patent No. 3213969 Japanese Patent Laid-Open No. 3-50586

In view of the above background, the present invention aims to provide a sheet-like laminate having a structure in which a toner image is recorded between a transparent film and a white substrate, and has the following two objects.
(1) An image having high gloss, smooth surface quality, and high image quality (good graininess) is realized by an electrophotographic method.
(2) The above-described object is achieved while having the same functions as those of the conventional image forming apparatus without making a significant change to the conventional image forming apparatus.

  In the image forming apparatus of the present invention, a mirror image toner image (an image with the original image turned upside down) is transferred and fixed on a transparent film sent from a dedicated paper feeding cassette. This transparent film is returned to the normal sheet conveying path using the sheet conveying path for double-sided output, and is similarly bonded to the white substrate sent from the dedicated sheet feeding cassette. In this case, the side of the transparent film on which the toner image is fixed is superimposed on the white substrate. Then, the overlapping sheet is adhered again through the fixing unit, thereby obtaining an image in which the toner image is sandwiched between the transparent film and the white substrate.

  According to the first aspect of the present invention, after a toner image of a mirror image of a document is transferred and fixed on a transparent film in a transfer unit / fixing unit, the transparent film is transferred to a normal sheet conveying path using a sheet conveying path for double-sided output. Then, the white substrate conveyed by the normal sheet conveyance path and the surface of the transparent film on which the toner image is transferred and fixed are overlapped to form a polymer sheet, and the polymer sheet is passed through the fixing unit. An image forming apparatus characterized in that an image having a toner image sandwiched between a transparent film and a white substrate (a laminate on which the toner image is recorded) is obtained by bonding the transparent film and the white substrate. .

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a normal double-sided image output mode and an image in which a toner image is sandwiched between a transparent film and a white substrate are output (nipping). And an image output mode.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, a mode in which a switching claw for switching a paper conveyance direction is installed in the conveyance path for double-sided output to perform normal double-sided image output, and transparent The image forming apparatus is characterized in that the sheet conveyance path is switched in a mode in which an image in a form in which a toner image is sandwiched between a film and a white substrate is output (clamped image output).
According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect, the transparent film and the white substrate are superimposed on a registration roller positioned upstream of the transfer portion. Forming device.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, an adhesive layer made of a heat-fusible resin is applied to the surface of the white substrate to a thickness of 1 to 20 μm. The image forming apparatus is characterized in that the transparent film and the white substrate are adhered by melting the toner at the fixing portion.
A sixth aspect of the present invention is the image forming apparatus according to the fifth aspect, wherein the softening point of the adhesive layer applied to the white substrate is lower than the softening point of the toner.
According to a seventh aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth or sixth aspect, the transparent film and the white substrate have a temperature higher than the first fixing temperature at which the toner image is fixed on the transparent film. The image forming apparatus is characterized in that the fixing temperature at the second time of bonding is lower.

The effects of the present invention are the following two.
(1) A high-gloss, smooth surface quality and high-quality (good graininess) image was realized by electrophotography.
(2) The above object has been achieved with the same functions as those of the conventional image forming apparatus without significant changes to the conventional image forming apparatus.

Hereinafter, the effects of the present invention will be described according to the claims.
According to the first aspect of the present invention, it is possible to obtain an image having high gloss, smooth surface quality, and high image quality (good graininess). Once the toner image is transferred and fixed on a transparent film, it leads to high image quality. By using the conveyance path for double-sided output, a large-scale device for bonding the transparent film and the white substrate is not necessary, and it is not necessary to make a significant change to the conventional image forming apparatus.
According to the second aspect of the present invention, both the normal image double-sided output, the high glossy and smooth surface quality using the transparent film, and the high image quality (granularity) can be achieved without significantly changing the conventional image forming apparatus. The same device can output the image.
According to the invention of claim 3, in order to adhere the surface side of the transparent film on which the toner image is fixed to the white substrate, it is not necessary to reverse the transparent film. In the mode in which the normal double-sided image output is performed, it is possible to invert the paper, and in the mode in which the toner image is output to the transparent film and the white substrate, the transparent film is not inverted.
According to the invention of claim 4, the transparent film and the white substrate can be superimposed without greatly changing the configuration of the conventional image forming apparatus. If you try to overlap in other places, extra space is required.
According to the invention of claim 5, the transparent film and the white substrate can be bonded at the fixing portion.
According to the sixth and seventh aspects of the invention, the transparent film and the white substrate can be bonded without disturbing the toner image formed on the transparent film.

  First, a conventional general image forming apparatus will be described. FIG. 1 is an explanatory diagram of the overall configuration showing an example thereof. A conventional general image forming apparatus 1 includes an image forming apparatus main body (hereinafter referred to as an apparatus main body) 1A having elements for forming an image by an electrophotographic process, and is detachably provided on the apparatus main body 1A. And a double-sided transfer unit 1B.

  A four-stage sheet cassette 3 is provided at the lower part of the apparatus main body 1A. In the sheet conveyance path extending upward from the sheet feeding cassette 3, that is, the vertical conveyance path of the transfer paper (transfer material, paper) P, the registration roller 4 and the drum-shaped photosensitive are sequentially arranged from the upstream side in the conveyance direction of the transfer paper P. An image forming unit 5 comprising an electrophotographic process means (element) around the body 5a, a transfer unit 6 for transferring a toner image formed on the photoconductor 5a onto a transfer paper P, and a fixing unit 7 are arranged. ing. The transfer unit 6 has a transfer roller 6a. A transfer paper conveyance guide member 8 is disposed between the transfer unit 6 and the fixing unit 7. The transfer paper transport guide member 8 forms a substantially vertical transport path for transporting the transfer paper P from the transfer unit 6 to the fixing unit 7. A switching claw 9 is provided on the downstream side of the fixing unit 7. The transfer sheet P that has passed through the fixing unit 7 is discharged by the switching claw 9 to the sheet discharge tray 11 on the upper surface of the apparatus main body 1A, and the double-sided conveyance path for conveyance to the double-sided transfer unit 1B side. 12 is sent to either.

  A paper discharge roller 13 is provided on the downstream side of the paper discharge path 10, and this paper discharge roller 13 is provided at a position facing the paper discharge tray 11. The double-sided conveyance path 12 communicates with an upper opening 14 serving as an entrance of the transfer paper P of the double-sided transfer unit 1B, and the transfer paper P is sent into the double-sided transfer unit 1B. Inside the double-sided transfer unit 1B, a retreat path 15 and a transport path 16 from the retreat path 15 to the registration roller 4 of the apparatus main body 1 are provided. Further, reversing rollers 17 and 18 and a switching claw 19 are arranged inside the double-sided transfer unit 1B.

  The transfer paper P transported into the double-sided transfer unit 1B is switched back by the reverse rollers 17 and 18, and is reversed with the rear end side of the transfer paper P as the leading edge. Next, the position of the switching claw 19 is switched, and the transfer paper P is guided and conveyed by the switching claw 19 into the conveyance path 16 and enters the apparatus main body 1A again from the lower opening 20. Next, the transfer paper P is sent to the registration roller 4 so that the surface opposite to the surface on which the toner image is first formed faces the image forming unit 5. As a result, the transfer paper P re-fed to the image forming unit 5 forms a toner image on the back surface, and after the toner image on the back surface is fixed by the fixing unit 7, it is placed on the paper discharge tray 11 by the paper discharge roller 13. The paper is ejected.

The present invention will be described below with reference to an embodiment shown in the drawings, but the present invention is not limited to this embodiment.
FIG. 2 is a diagram illustrating the overall configuration of the image forming apparatus 100 according to the present invention. The difference from the conventional image forming apparatus 1 described above is that the image forming apparatus main body 100A is provided with a dedicated paper feeding cassette 101 for outputting a high-gloss and high-quality image, and the double-side transfer unit 100B is special. This is the point that a simple switching claw 102 is provided. Thus, it is a feature of the present invention that no significant changes are made to the conventional image forming apparatus. Furthermore, it is a feature of the present invention that it has the same function as a conventional image forming apparatus and can output a high-gloss and high-quality image.

  The image forming apparatus of the present invention performs the same operation as a conventional image forming apparatus during normal image output. This is the same as that described above for the conventional general image forming apparatus.

  The image forming apparatus 100 of the present invention further includes an operation mode for outputting a high-gloss and high-quality image. The high gloss / high quality image output mode will be described. In this operation mode, the dedicated paper feed cassette 101 is used. In the dedicated paper cassette 101, transparent films Q and white substrates W are alternately stacked as shown in FIG.

  The operation of the image forming apparatus will be described. First, the transparent film Q is transported along a normal transport path. The image forming unit 5 forms a mirror image toner image as an output target image. Then, the mirror image is transferred onto the transparent film by the transfer unit 6 and fixed by the fixing unit 7. The transparent film that has passed through the fixing unit 7 is sent by the switching claw 9 to the double-sided transfer path 12 for transfer to the double-sided transfer unit 100B, and is sent into the double-sided transfer unit 100B from the opening 14. In the case of normal double-sided output, since it is necessary to reverse the paper, the paper is once entered into the retreat path 15 via the reverse rollers 17 and 18. In this high-gloss / high-quality image output mode, a transparent film is used. Since there is no need to reverse, the transparent claw is sent directly to the conveyance path 16 by the switching claw 102. Then, the transparent film is returned to the normal conveyance path through the opening 20 and sent to the registration roller 4. At the same time, the white substrate W is sent from the dedicated paper cassette 101 to the registration roller 4. In other words, the transparent film Q and the white substrate W are superimposed on the registration roller 4.

  The situation is illustrated in FIG. The transparent film Q has the surface on which the toner image is formed facing the white substrate W. Thereafter, the image forming section 5 and the transfer section 6 are not operated, and the superposed film of the transparent film and the white substrate is transported along the transport path. Then, the heat-sealable resin (adhesive layer) previously applied on the white substrate is melted by the fixing unit 7 to bond the transparent film and the white substrate, and the adhesive (polymerized sheet) is discharged by the discharge roller 13. The paper is discharged onto the tray 11.

  The image G (laminated body on which the toner image is recorded) output by the above operation is obtained by superimposing the transparent film Q, the toner image T, and the white substrate W in this order as shown in FIG. The obtained image is viewed from the transparent film side. Since the mirror image toner image of the target image is transferred and fixed on the transparent film, the normal image is viewed.

The switching claw 102 of the double-sided transfer unit 100B, which is a feature of the present invention, will be described with reference to FIGS.
When duplex printing is performed on normal paper, the duplex transfer unit 100B of the present invention operates in the same manner as a conventional image forming apparatus. In this case, first, as shown in FIG. 6, the paper P is fed toward the reverse rollers 17 and 18. After the paper is sufficiently fed, the position of the switching claw 102 is switched (rotated) as shown in FIG. 7, and the paper is fed in the reverse direction to reverse the paper.

  In the operation mode for outputting a high-gloss and high-quality image, the switching claw 102 is as shown in FIG. 8 (rotates), and the transparent film Q is fed without being reversed. This is because, in order to obtain a high-gloss and high-quality image, the side of the transparent film on which the toner image is fixed needs to be in contact with the white substrate.

  In the present invention, the mechanism using the double-sided transfer conveyance path provided with the switching claw 102 allows the transparent film and the white substrate to be supplied from the same dedicated paper feed cassette 101 (FIGS. 2 to 4). There is no need to provide a conveyance path, and the image forming apparatus is prevented from having a complicated configuration.

  The transparent film of this invention can use the thing of the conventional OHP use as it is. Specifically, it is a heat-resistant resin film having a maximum use temperature of 100 ° C. or higher without causing significant thermal deformation by heating during fixing (usually 100 ° C. or higher). As the material, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (nylon), polyimide or the like is used. Among these, PET is particularly preferable in terms of heat resistance and transparency.

  The thickness of the transparent film formed from the material as described above should be such that wrinkles do not occur even when the sheet becomes soft due to heating during toner image fixing. For example, in the case of polyethylene terephthalate, 20 μm or more is desirable. . Further, when the thickness is increased, the transmissivity is lowered and there is a problem in image quality. Therefore, the thickness is desirably 200 μm or less. That is, the thickness of the transparent film is suitably 30 to 200 μm.

  The white substrate W of the present invention is formed by applying an adhesive layer A to a white substrate B as shown in FIG. It is desirable to use paper for the white substrate, and the type of paper is not particularly limited. In some cases, a white resin with high heat resistance may be used (for example, synthetic paper).

  A transparent heat-fusible resin is used for the adhesive layer. Conventionally, it is common to laminate a surface with a transparent film after forming a toner image on paper, and a technique of providing an adhesive layer of a heat-fusible resin on a transparent film and laminating the paper with heat is known. . In the present invention, an adhesive layer of heat-fusible resin is provided on the paper side, but the same adhesive can be used because the purpose of bonding the paper and the transparent film is the same.

  That is, the adhesive layer can be formed by applying a thermoplastic resin as a main component and an additive added as necessary. Examples of the thermoplastic resin that forms the adhesive layer include polyester resins, polystyrene resins, acrylic resins, polyurethane resins, acrylic urethane resins, epoxy resins, phenoxy resins, resins obtained by modifying these resins with silicone, Examples thereof include a mixture and an ultraviolet blocking resin. In addition to this, an ultraviolet absorber, an organic filler and / or an inorganic filler can be appropriately added as necessary. The thickness of the adhesive layer is desirably 1 to 20 μm.

  In the present invention, it is desirable that the softening point of the resin used for the adhesive layer of the white substrate is 20 ° C. or more lower than the softening point of the toner binder resin. The softening point referred to here is a 1/2 method softening point. Under a specific condition, while applying a predetermined extrusion load, a preheating time at an initial set temperature (for example, 50 ° C.), for example, after 300 seconds, It is evaluated by a temperature that is one-half of the difference in piston stroke at the start and end of outflow at each temperature when the temperature is increased at a constant temperature increase rate of, for example, a flow tester CFT-500 or 500D manufactured by Shimadzu Corporation. Can be measured.

  As a feature of the present invention, a toner image is once fixed on a transparent film, and then fixed (adhered) again by being superimposed on a white substrate. At this time, the toner image formed on the transparent film by the first fixing may be disturbed because the toner is excessively melted by the second fixing. In order to prevent this, it is desirable for the second fixing to have a smaller heat energy than to the first fixing. Therefore, it is desirable that the second fixing temperature is lower than the first fixing temperature. Other methods include shortening the passage time by increasing the linear speed of the fixing unit, or narrowing the nip width of the fixing roller. Therefore, there is a condition that the softening point of the resin used for the adhesive layer of the white substrate is preferably lower than the softening point of the binder resin of the toner so that the transparent film and the white substrate are properly bonded even at low heat energy. Arise.

In the present invention, an image having high gloss, smooth surface quality and high image quality (good graininess) can be obtained. This will be described.
(1) High Glossy and Smooth Surface Quality As shown in FIG. 5, since the outermost surface of the image obtained by the present invention is a transparent film, a high glossy image is obtained reflecting the glossiness of the transparent film. Can do. It is well known that high gloss makes the color darker and more vivid.

Furthermore, in the present invention, unlike the ordinary laminating method, the toner is first transferred and fixed on the transparent film side, so that the toner surface adheres smoothly to the transparent film as shown in FIG. This makes it possible to achieve a smooth surface quality that exceeds that of a normal laminating method. In the normal laminating method, the state as shown in FIG. 11 is obtained, and the toner surface cannot be completely adhered to the transparent film. Therefore, scattering and reflection of light occur at the boundary, which hinders smooth surface quality. Become.
On the other hand, the image obtained by the present invention adheres smoothly as shown in FIG. 10, and since the difference in the refractive index between the toner and the film is small, the light is almost scattered / reflected at the boundary surface between the toner and the film. Pass through without being. As a result, a very smooth surface quality can be achieved.

(2) High image quality (good graininess)
The graininess represents “feeling of roughness” due to uneven image density, and is an index most regarded as important when evaluating images such as photographs. This can be quantified as granularity. That is, the graininess is defined as “subjective evaluation value indicating how rough the image that should be uniform is”. An amount that objectively represents the granularity, which is a subjective evaluation value, is an evaluation scale of granularity, and is “granularity”. RMS granularity is standardized as this granularity, and is standardized by ANSI · PH-2.40-1985.
In an electrophotographic image forming apparatus, since large particles such as toner are used, the size and position of dots vary, so it is difficult to achieve image quality with good graininess. In the present invention, by transferring and fixing the toner on the transparent film, an image having better graininess than the conventional image forming apparatus can be achieved. This will be described below.

  First, unlike a paper, a transparent film has a smooth surface and a uniform dielectric constant, so that the dot disturbance at the transfer portion is small. Furthermore, when a toner image is fixed on paper, the toner enters the unevenness of the paper and the fibers of the paper are exposed, which leads to deterioration of the graininess, but the transparent film has a smooth surface. There is no problem.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to the following Example, unless it deviates from the meaning.
[Example 1]
A commercially available electrophotographic copying machine was modified to obtain the image forming apparatus of the present invention shown in FIG. As the transparent film, a PET film having a thickness of 80 μm was used. Ricoh FC glossy paper <thick mouth> was used for the white base substrate, and an adhesive layer was applied thereon so that the thickness was about 10 μm. The resin used for the adhesive layer is appropriately mixed with polyester resin, toluene, and methyl ethyl ketone so that the softening point is approximately 20 degrees lower than the toner used, and the second fixing temperature for bonding the transparent film and the white substrate is The temperature was controlled to be 20 degrees lower than the normal fixing temperature.

The measurement results of the obtained image are shown in Table 1 below. Since there is no measurement method for the smoothness index, it was judged visually by the following criteria.
○: Very smooth.
Δ: Smooth.
X: Not smooth.

[Comparative Example 1]
In the image forming apparatus of Example 1, an image was output to Ricoh FC glossy paper <thick mouth> using a normal image output mode. The measurement results of the obtained image are shown in Table 1 below. Since there is no measurement method for the smoothness index, it was judged visually based on the above criteria.

[Comparative Example 2]
In the image forming apparatus of Example 1, an image was output to Ricoh FC glossy paper <thick mouth> using a normal image output mode, and then the surface was laminated by a commercially available laminator. The measurement results of the obtained image are shown in Table 1 below. Since there is no measurement method for the smoothness index, it was judged visually based on the above criteria.

It is explanatory drawing which shows the structure of the conventional image forming apparatus. 1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to the present invention. It is explanatory drawing which shows the set state of the transparent film and white base | substrate to a dedicated paper feeding cassette. It is a schematic diagram which shows the superimposition of the transparent film and white base | substrate with a registration roller. It is a schematic diagram of an image (a laminate on which a toner image is recorded) obtained by the present invention. It is operation | movement explanatory drawing (the 1) of a switching claw. It is operation | movement explanatory drawing (the 2) of a switching nail | claw. It is operation | movement explanatory drawing (the 3) of a switching nail | claw. It is explanatory drawing of a white base | substrate. It is explanatory drawing which shows the image obtained by this invention. It is explanatory drawing which shows the image by a normal laminating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Image forming apparatus main body 1B Duplex transfer unit 3 Paper feed cassette 4 Registration roller 5a Photoreceptor 5 Image forming part 6 Transfer part 6a Transfer roller 7 Fixing part 8 Transfer paper conveyance guide member 9 Switching claw 10 Paper discharge path 11 Paper discharge tray 12 Double-side transport path 13 Paper discharge roller 14 Opening 15 Retraction path 16 Transport path 17, 18 Reverse roller 19 Switching claw 20 Opening 100 Image forming apparatus 100A Image forming apparatus main body 100B Duplex transfer unit 101 Dedicated paper feed cassette 102 Switching claw A Adhesive layer B White substrate G Laminate with toner image recorded P Transfer paper (transfer material, paper)
Q Transparent film W White substrate

Claims (7)

  After the toner image of the mirror image of the original is transferred and fixed on the transparent film in the transfer unit / fixing unit, the transparent film is returned to the normal sheet transport path using the sheet transport path for double-sided output, and the normal sheet transport is performed. The white substrate conveyed by the road and the transparent film are superposed so that the surface on which the toner image of the transparent film is transferred and fixed are in contact with each other to form a polymer sheet. The polymer sheet is bonded to the transparent film and the white substrate through the fixing unit. By doing so, an image forming apparatus is obtained in which a toner image is sandwiched between a transparent film and a white substrate.   The image forming apparatus according to claim 1, further comprising: a mode for performing normal double-sided image output; and a mode for outputting an image in which a toner image is sandwiched between a transparent film and a white substrate. An image forming apparatus.   The image forming apparatus according to claim 2, wherein a switching claw for switching a paper conveyance direction is installed in the conveyance path for double-sided output to perform normal double-sided image output, and between the transparent film and the white substrate. An image forming apparatus, wherein a sheet conveyance path is switched between a mode in which an image in a form in which a toner image is sandwiched is output.   4. The image forming apparatus according to claim 1, wherein the transparent film and the white substrate are superposed on a registration roller located upstream of the transfer portion.   5. The image forming apparatus according to claim 1, wherein an adhesive layer made of a heat-fusible resin is applied to a white substrate surface in a thickness of 1 to 20 [mu] m and melted at a fixing portion. An image forming apparatus characterized in that a transparent film and a white substrate are adhered.   6. The image forming apparatus according to claim 5, wherein the softening point of the adhesive layer applied to the white substrate is lower than the softening point of the toner. 7. The image forming apparatus according to claim 1, wherein the second fixing for bonding the transparent film and the white substrate is performed at a temperature higher than the first fixing temperature for fixing the toner image on the transparent film. An image forming apparatus having a lower temperature.

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