JP4882345B2 - Copying apparatus and copying method - Google Patents

Description

  The present invention relates to a technique for faithfully reproducing and copying an original.

In a copying apparatus for copying an original, one of the basic characteristics is required to be a faithful copy of the original. Copy fidelity is realized by, for example, high resolution and accurate color reproduction. In order to perform accurate color reproduction, it is necessary to accurately read the color of the document and accurately reproduce the read color. There are various techniques for performing accurate color reproduction. For example, in the technique described in Patent Document 1, an image containing a fluorescent material is recognized by irradiating an original with ultraviolet light, and this image is converted into a fluorescent toner. It has been reproduced using. In this way, it is possible to more faithfully reproduce a fluorescent color image that has been apt to be reproduced with a different color.
JP-A-10-107970

  Incidentally, a fluorescent material is added to some sheets for the purpose of improving the whiteness of the sheet. Also, some papers containing waste paper or the like and unbleached papers have low whiteness. Therefore, the whiteness of the original paper and the copy paper does not necessarily match, but if the whiteness of the original paper and the copy paper do not match, the appearance of the copy will be different from that of the original. There is a problem. However, as is the case with the technique described in Patent Document 1, the conventional color reproduction technique is a technique mainly for an image formed on the surface of a document. For this reason, no consideration has been given to the area where the background paper itself is exposed.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a technique that allows a document to be copied more faithfully in consideration of the whiteness of a sheet.

In order to achieve the above-described object, according to the present invention, the irradiating means for irradiating the original on which the original image is formed, and the diffuse reflected light and the fluorescence from the original irradiated with light by the irradiating means are different from each other. Light receiving means that receives light with spectral sensitivity and generates image information indicating the intensity of diffusely reflected light from the original and fluorescence information indicating the intensity of fluorescence from the original, and a light receiving means generated by the light receiving means A determination unit that determines whether the fluorescence intensity indicated by the fluorescence information exceeds a predetermined threshold; and an image forming unit that forms an image corresponding to the image information generated by the light receiving unit on a sheet using a color material. there, when the intensity of the fluorescence is determined to exceed the predetermined threshold value by the determination means, while at least impart color material colored to a region corresponding to the original image, at least the document image By applying a colorant containing a fluorescent material with respect to not formed the background region to provide a copying apparatus and an image forming means for forming an image.
According to this copying apparatus, when the intensity of fluorescence from a document is high, a toner image is formed on a sheet (recording paper) with a color material including a fluorescent material. As a result, the apparent whiteness of the copy is improved and the color of the entire copy is closer to that of the original.

  In the copying apparatus, it is preferable that the irradiating unit irradiates the original with light having a spectral energy distribution over at least the entire visible region. Preferably, the light receiving means has a plurality of light receiving element rows of at least four rows, and each light receiving element row has a different spectral sensitivity. With such a configuration, it is possible to read the document more accurately.

  In this copying apparatus, it is preferable that the light receiving means is configured to selectively receive light having a wavelength of 430 ± 30 nm and generate fluorescence information indicating the intensity of fluorescence from the original. This is because the fluorescent wavelength of the fluorescent material contained in the paper is generally around 430 nm. Further, by selectively receiving light in a narrow wavelength region, diffuse reflected light from the original can be separated well, so it is possible to more easily determine whether or not the light is fluorescent. .

  In the copying apparatus, the color material including the fluorescent material is, for example, a color material that is transparent on the sheet. Here, the color material is, for example, toner. However, of course, this color material may be white.

Further, the copying apparatus is provided with detection means for detecting the intensity of the fluorescence sheet emits an image is formed by the image forming means, said image forming means, wherein the fluorescence information and the detected intensity by the detection means In the case where there is a difference of a predetermined level or more with the fluorescence intensity to be displayed, a configuration may be adopted in which an image is formed by applying a color material including a fluorescent material to the background region .

The present invention can also be specified as a copying method performed by a copying apparatus. In this copying method, an irradiation step of irradiating light on a document on which a document image is formed, and diffuse reflected light and fluorescence from the document irradiated with light in the irradiation step are received with different spectral sensitivities, respectively. A light receiving step for generating image information indicating the intensity of diffusely reflected light from the document and fluorescence information indicating the intensity of fluorescence from the document, and a fluorescence intensity indicated by the fluorescence information generated in the light receiving step. A determination step of determining whether or not a predetermined threshold value is exceeded, and an image formation step of forming an image corresponding to the image information generated in the light receiving step on a sheet using a color material, wherein the determination step includes the step If it is determined that the intensity of the fluorescence exceeds a predetermined threshold value, at least a colored color material is applied to the area corresponding to the original image, and Both those characterized by having an image forming step of forming an image by applying a colorant containing a fluorescent material with respect to a background region where the original image is not formed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, an electrophotographic copying apparatus will be described as an embodiment of the present invention. In the following description, “original” to be read is defined as “paper on which some image is formed”, and an area where no image is formed is defined as “background”. However, this does not mean that the original in the present invention is limited to such a sheet.

[1. Constitution]
FIG. 1 is a block diagram schematically showing the configuration of a copying apparatus 100 according to an embodiment of the present invention. FIG. 2 is a diagram more specifically showing the configuration of the image reading unit 10 and the image forming unit 20 of the copying apparatus 100. First, the configuration of the image reading unit 10 and the image forming unit 20 will be described in detail.

  The image reading unit 10 has a so-called image scanner function, and the image forming unit 20 has a so-called printer function. Among these, the image reading unit 10 includes a platen glass 11, a platen cover 12, a full rate carriage 13, a half rate carriage 14, an imaging lens 15, and a line sensor 16.

  The platen glass 11 is a transparent glass plate on which the document O to be read is placed. The platen glass 11 is installed so that the surface thereof is horizontal. Further, a reflection suppressing layer such as a multilayer dielectric film is formed on the surface of the platen glass 11 so that reflection on the surface of the platen glass 11 is reduced. This is to prevent the reflected light component from the surface of the original O, which is a component to be read, and the reflected light component from the surface of the platen glass 11, which is an unnecessary component, from being read in a combined state. For the purpose of separating the reflected light component from the original O and the reflected light component from the surface of the platen glass 11, for example, a spacer is provided so that the surface of the original O and the surface of the platen glass 11 are separated by a predetermined distance. It may be.

  The platen cover 12 is provided so as to cover the platen glass 11 and blocks the external light to facilitate reading of the document O placed on the platen glass 11. The full rate carriage 13 includes a light source 131 and a mirror 132. The light source 131 is a single light source whose spectral energy distribution covers at least the entire visible region, and is, for example, a tungsten halogen lamp or a xenon arc lamp. The light source 131 irradiates the original O with light having a predetermined intensity at an incident angle of about 45 °. The spectral energy distribution of the light source 131 preferably includes the ultraviolet region as much as natural light. In this way, accurate reading can be performed even when the excitation wavelength of the fluorescent material is included in the ultraviolet region.

  The mirror 132 further reflects the reflected light from the document O, and forms an optical path (one-dot chain line in the figure) that guides this light to the half-rate carriage 14. Since the light incident on the mirror 132 is light reflected at a reflection angle of about 0 ° with respect to the reflection surface of the document O, most of the light is diffusely reflected light. The full-rate carriage 13 moves in the direction of arrow A or B in FIG. 2 during scanning, and scans the entire surface while irradiating the original O with light.

  The half-rate carriage 14 includes mirrors 141 and 142 and forms an optical path that guides light from the full-rate carriage 13 to the imaging lens 15. The half-rate carriage 14 is driven by a drive mechanism (not shown), and is moved in the same direction as the full-rate carriage 13 at a half speed of the full-rate carriage 13 during scanning.

  The imaging lens 15 is provided on the optical path connecting the mirror 142 and the line sensor 16, and images the light from the document O at the position of the line sensor 16. The line sensor 16 is, for example, a multi-line CCD image sensor (light receiving element array) provided with an on-chip color filter. This CCD image sensor images the original O with different spectral sensitivities for each line, and generates an image signal. In the present embodiment, a CCD image sensor having peaks in the wavelength regions of four colors of purple (P), blue (B), green (G), and red (R) is used.

  For convenience of explanation, these four color CCD image sensors are hereinafter referred to as “P sensor”, “B sensor”, “G sensor”, and “R sensor”. The image signals output from these CCD image sensors are referred to as “P image signal”, “B image signal”, “G image signal”, and “R image signal”, respectively.

  The color filters of the R sensor, G sensor, and B sensor are normal primary color filters. On the other hand, the color filter of the P sensor is a narrow band filter having a light receiving sensitivity peak in the vicinity of 430 nm, and its half width is about 20 to 30 nm. This P sensor selectively receives light having a wavelength near 430 nm. By selectively receiving light in this wavelength region, it is possible to detect fluorescence emitted by the paper.

  FIG. 3 is a diagram showing the spectral reflectance of various types of paper (here, papers on which images are not formed). In the figure, the vertical axis represents the spectral reflectance R, and the horizontal axis represents the wavelength λ of the incident light. As shown in the figure, some of the paper has a reflectance peak near 430 nm, and some of the reflectance exceeds 100%. The reflectance exceeding 100% means that there is reflection more than the incident light, which means that fluorescence is generated. The fluorescence emitted from the paper is caused by the fluorescent material added to the paper. The fluorescent wavelength of the fluorescent material contained in the paper is generally around 430 nm.

  The configuration of the image reading unit 10 is as described above. Next, the configuration of the image forming unit 20 will be described with reference to FIG. 2 again. The image forming unit 20 includes a plurality of paper feed trays 21, a plurality of transport rolls 22, primary transfer units 23 a, 23 b, 23 c and 23 d, an intermediate transfer belt 24, a secondary transfer roll 25, and a backup roll 26. And a fixing mechanism 27.

  Each of the paper feed trays 21 stores recording paper of a predetermined size and supplies the recording paper in accordance with image formation. Here, the recording sheet is a sheet for recording an image, and is a sheet-like recording material usually used in image formation such as a so-called PPC (Plain Paper Copier) sheet. In addition, a recording material made of a material other than paper or paper whose surface is coated with resin or the like can be used. Note that the recording paper used in the present embodiment is a paper having a predetermined whiteness.

  The transport roll 22 forms a transport path for transporting the recording paper supplied from the paper feed tray 21 to a position where the secondary transfer roll 25 and the backup roll 26 face each other. The recording paper conveyance path is a path indicated by a broken line in FIG. The primary transfer units 23 a, 23 b, 23 c and 23 d form toner images corresponding to the supplied image data, and transfer the formed toner images to the intermediate transfer belt 24.

  Here, the configuration of the primary transfer unit 23a will be described in more detail with reference to FIG. The primary transfer unit 23 includes a photosensitive drum 231, a charger 232, an exposure device 233, developing units 234 and 235, and a primary transfer roll 236. The photosensitive drum 231 is an image carrier having a photoconductive layer made of OPC (Organic Photo Conductor) as a charge acceptor formed on the surface thereof, and is rotated in the direction of arrow C in the figure. The charger 232 includes a charging roller, and uniformly charges the surface of the photosensitive drum 231. The exposure device 233 irradiates the photosensitive drum 231 with light by a laser diode, and forms an electrostatic latent image with a predetermined potential on the surface thereof. The developing units 234 and 235 each store toner of different colors and generate a predetermined potential difference (development bias) between the surface of the photosensitive drum 231 and electrostatic potential formed on the surface of the photosensitive drum 231 by this potential difference. A toner image is formed by attaching toner to the latent image. The developing units 234 and 235 constitute a so-called rotary developing device. The primary transfer roll 236 generates a predetermined potential difference (primary transfer bias) at a position where the intermediate transfer belt 24 faces the photosensitive drum 231, and transfers a toner image onto the surface of the intermediate transfer belt 24 by this potential difference.

The toners stored in the developing units 234 and 235 are yellow (Y) and transparent toner, respectively. Here, the transparent toner is a toner that does not contain a color material. For example, SiO ₂ (silicon dioxide) or TiO ₂ (titanium dioxide) is externally added to a low molecular weight polyester resin. The transparent toner is fixed on the recording paper in a state of being transparent by heating. A fluorescent material is added to the transparent toner of this embodiment, and the apparent whiteness of the recording paper surface can be increased by forming an image with the transparent toner.

  The primary transfer units 23b, 23c, and 23d have the same configuration as the primary transfer unit 23a except that the development units are different. The developing units of the primary transfer units 23b, 23c, and 23d are monochromatic developing devices, and form magenta (M), cyan (C), and black (K) toner images, respectively.

  Here, referring back to FIG. 2, the other components of the image forming unit 20 will be described. The intermediate transfer belt 24 is an endless belt member that is moved in the direction of arrow D in the drawing by a driving mechanism (not shown). The intermediate transfer belt 24 transfers (primary transfer) a toner image at a position facing the photosensitive drums 231a to 231d, and moves the toner image to transfer (secondary transfer) onto a recording sheet. The secondary transfer roll 25 and the backup roll 26 cause a predetermined potential difference (secondary transfer bias) at a position where the intermediate transfer belt 24 faces the recording sheet, and transfers the toner image onto the recording sheet. The fixing mechanism 27 includes a roll member for heating and pressurizing the recording paper, and fixes the toner image transferred to the surface of the recording paper.

  The configurations of the image reading unit 10 and the image forming unit 20 are as described above. Next, another configuration of the copying apparatus 100 will be described with reference to the block diagram of FIG. The copying apparatus 100 includes a control unit 30, a storage unit 40, an image processing unit 50, an operation unit 60, and a communication unit 70 in addition to the image reading unit 10 and the image forming unit 20 described above.

  The control unit 30 is an arithmetic unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. (not shown), and is copied by executing a program stored in the storage unit 40. The operation of each part of the apparatus 100 is controlled. The storage unit 40 is a large-capacity storage device such as an HDD (Hard Disk Drive), and stores various data including programs for operating the respective units of the copying apparatus 100 described above. The storage unit 40 stores a threshold value Th used for comparison with fluorescence data described later.

  The image processing unit 50 includes an image processing circuit such as an ASIC (Application Specific Integrated Circuit) or an LSI (Large Scale Integration), and an image memory that temporarily stores image data, and executes predetermined image processing. Here, the image processing includes basic image processing such as AD conversion and shading correction, and processing such as color space conversion, image rotation, image enlargement / reduction, under color removal (UCR) processing, and screen processing.

  The operation unit 60 is, for example, an input device including a touch panel display and various buttons, and receives an input instruction from an operator. This input instruction is supplied to the control unit 30. The communication unit 70 is an interface device for exchanging data with an external device. The copying apparatus 100 can output image data generated by the image reading unit 10 to an external device such as a computer, or can receive image data from the external device as necessary.

[2. Operation]
With the above configuration, the copying apparatus 100 scans the document O placed on the platen glass 11 to generate image data indicating the document O, and forms an image based on the image data on a recording sheet. To do. Hereinafter, a series of processing performed by the copying apparatus 100 from scanning of the document O to image formation will be described with reference to the flowchart of FIG.

  When the document O is placed on the platen glass 11 and the operator instructs the start of image formation, the control unit 30 of the copying apparatus 100 scans the document O placed on the image reading unit 10 (step S1). . In response to this instruction, the image reading unit 10 irradiates the original O with light while moving the full-rate carriage 13 and the half-rate carriage 14, picks up the reflected light with the line sensor 16, and R, G, B, and P An image signal for each color is generated.

  Subsequently, the control unit 30 supplies the image signal generated by the image reading unit 10 to the image processing unit 50, and generates data based on the image signal. At this time, the image processing unit 50 performs image processing such as AD conversion, shading correction, color space conversion, UCR processing, and screen processing on the R, G, and B image signals, thereby forming the image signal on the surface of the document O. Image data representing the captured image is generated (step S2).

  Further, the image processing unit 50 executes image processing such as AD conversion and shading correction on the P image signal, and generates fluorescence data as a result of the execution (step S3). As described above, since the P image signal is generated by selectively receiving light in the vicinity of 430 nm, it represents the intensity of fluorescence from the document O. The image processing unit 50 supplies this fluorescence data to the control unit 30.

  The control unit 30 supplied with the fluorescence data determines whether or not to form a toner image with transparent toner based on this data (step S4). Whether or not to form a toner image with transparent toner is determined by comparing the intensity of received light indicated by the fluorescence data with the above-mentioned threshold value Th. Specifically, for example, the fluorescence data corresponding to a predetermined area of the document may be compared with the threshold Th, or the average value of the fluorescence data corresponding to the entire area of the document may be compared with the threshold Th. Good. Note that the value of the threshold Th is arbitrary, but an example is a value corresponding to the received light intensity when the spectral reflectance is 100%.

  In this determination process, when the intensity (or the average value) indicated by the fluorescence data exceeds the threshold value Th (step S4; YES), the control unit 30 determines to form a toner image with transparent toner. Therefore, the control unit 30 instructs the image forming unit 20 to form a toner image with transparent toner (step S5). In response to this instruction, the image forming unit 20 forms a toner image with transparent toner in the primary transfer unit 23 a and transfers the toner image to the intermediate transfer belt 24.

  The toner image formed at this time may be a toner image that covers the entire surface of the recording paper, or a toner image that covers only an area on the recording paper where an image corresponding to image data is not formed, that is, a background area. It may be. Further, for example, the amount of the fluorescent toner may be varied according to the intensity indicated by the fluorescence data, such that the amount of the fluorescent toner increases as the intensity indicated by the fluorescence data increases.

  In this determination process, when the intensity (or the average value) indicated by the fluorescence data is equal to or less than the threshold Th (step S4; NO), the control unit 30 omits the process of step S5 described above.

  Subsequently, the control unit 30 instructs the image forming unit 20 to form a toner image corresponding to the image data (step S6). In response to this instruction, the image forming unit 20 forms toner images of the respective Y, M, C, and K toners in the primary transfer units 23a, 23b, 23c, and 23d, and transfers the toner images to the intermediate transfer belt 24. . Thereafter, the image forming unit 20 transfers and fixes the toner image formed on the intermediate transfer belt 24 onto a recording sheet.

  Since the recording paper on which the image is formed in this manner forms a toner image with transparent toner in the background area, the apparent whiteness is improved by this toner image. As a result, the color of the recording paper, which is a copy, and the color of the original paper are well approximated, and the colors perceived by the observer match well. Therefore, according to the copying apparatus 100 of the present embodiment, it is possible to perform faithful copying to the original.

  Further, the copying apparatus 100 can form an image in which a so-called metamerism (conditional color) hardly occurs by irradiating the original with light having a spectral energy distribution over the entire visible region. Thereby, even if the light source used for observation is different, the color of the copy is less likely to change. Therefore, it is possible to observe the copy in a state where the original is faithfully reproduced, regardless of the observation conditions such as the light source.

[3. Modified example]
In addition, this invention is not limited only to embodiment mentioned above, It is possible to implement in a various aspect. Specifically, the following modifications are mentioned, for example. These modifications can be combined as appropriate.

  In the above-described embodiment, the line sensor 16 is shown as means for receiving light from the document. However, a configuration different from this can be adopted. For example, a light receiving element different from the CCD image sensor may be used. In addition, although it has been described that each light receiving element has a peak in the wavelength region of four colors, a configuration in which peaks of five colors or more are provided in order to perform more accurate reading.

  In the above-described embodiment, the toner (transparent toner) for improving the whiteness of the recording paper is a toner that does not contain a color material, that is, a toner that becomes transparent on the recording paper. Including toner may be used. Even when such toner is used, the whiteness of the recording paper can be improved.

  In the above-described embodiment, whether or not to form a toner image using transparent toner is determined by comparing the intensity of received light indicated by the fluorescence data with a predetermined threshold. You may compare. Specifically, for example, an optical sensor may be provided in the middle of the recording paper conveyance path or inside the paper feed tray to detect the whiteness of the recording paper, and the detection result may be compared with the fluorescence data. Then, when it is determined that the whiteness of the recording paper is lower than the whiteness of the original paper, or when it is determined that there is a difference of a predetermined level or more, a toner image is formed with transparent toner. In this way, since the whiteness of the recording paper can be taken into consideration, even if various different papers are used as the recording paper, it is possible to perform processing according to each paper. Of course, the operator can input the whiteness of the recording paper via the operation unit.

  In the above-described embodiment, an example in which a toner image using transparent toner is formed only in the background area has been described. However, in the case of an electrophotographic copying apparatus as in the above-described embodiment, a part of the image area (half In the tone area or the like, there may be an area where no toner image is formed, that is, an area where the recording paper is exposed. Therefore, in such a case, a toner image made of transparent toner may be formed in the entire area where the recording paper is exposed.

  Although the above-described embodiment shows an electrophotographic copying apparatus, the recording method is not limited to the electrophotographic method as a matter of course, and other recording methods such as an ink jet method are adopted. Is also possible.

1 is a block diagram schematically showing a configuration of a copying apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating configurations of an image reading unit and an image forming unit of the copying apparatus. It is the figure which showed the spectral reflectance of various paper. FIG. 2 is a diagram illustrating a configuration of a primary transfer unit of a copying apparatus. 5 is a flowchart illustrating a series of processing performed by the copying apparatus from scanning of a document to image formation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Copy machine, 10 ... Image reading part, 11 ... Platen glass, 12 ... Platen cover, 13 ... Full-rate carriage, 14 ... Half-rate carriage, 15 ... Imaging lens, 16 ... Line sensor, 20 ... Image formation part, 21 ... Feeding tray, 22 ... Conveying roll, 23, 23a, 23b, 23c, 23d ... Primary transfer unit, 24 ... Intermediate transfer belt, 25 ... Secondary transfer roll, 26 ... Backup roll, 27 ... Fixing mechanism, 30 ... Control 40, storage unit, 50 ... image processing unit, 60 ... operation unit, 70 ... communication unit

Claims (7)

Irradiating means for irradiating light on a document on which a document image is formed ;
The diffuse reflection light and the fluorescence from the document irradiated with light by the irradiation means are received with different spectral sensitivities, and image information indicating the intensity of the diffuse reflection light from the document and the fluorescence intensity from the document are obtained. A light receiving means for generating the fluorescence information in association with each other;
Determination means for determining whether the intensity of fluorescence indicated by the fluorescence information generated by the light receiving means exceeds a predetermined threshold;
An image forming unit that forms an image corresponding to the image information generated by the light receiving unit on a sheet using a color material, and the determination unit determines that the fluorescence intensity exceeds a predetermined threshold value. , while at least impart color material colored with respect to the corresponding regions in the original image, the image formation to form an image by applying a colorant containing a fluorescent material to at least the original image is not formed the background area And a copying apparatus. The irradiation means includes
The copying apparatus according to claim 1, wherein the original is irradiated with light having a spectral energy distribution over at least the entire visible region. The light receiving means is
The copying apparatus according to claim 1, wherein the copying apparatus includes at least four light receiving element arrays, and each light receiving element array has a different spectral sensitivity. The light receiving means is
2. The copying apparatus according to claim 1, wherein light having a wavelength of 430 ± 30 nm is selectively received, and fluorescence information representing the intensity of fluorescence from the original is generated. The copying apparatus according to claim 1, wherein the color material including the fluorescent material is a color material that is transparent on a sheet. A detecting means for detecting the intensity of fluorescence emitted by a sheet on which an image is formed by the image forming means;
The image forming unit applies a color material including a fluorescent material to the background region when there is a difference of a predetermined level or more between the intensity detected by the detecting unit and the intensity of fluorescence indicated by the fluorescence information. The copying apparatus according to claim 1, wherein an image is formed . An irradiation step for irradiating the original on which the original image is formed;
In the irradiation step, diffuse reflected light and fluorescence from the document irradiated with light are received with different spectral sensitivities, and image information indicating the intensity of the diffuse reflected light from the document and fluorescence intensity from the document are obtained. A light receiving step for generating the fluorescence information in association with each other;
A determination step of determining whether or not the fluorescence intensity indicated by the fluorescence information generated in the light receiving step exceeds a predetermined threshold;
An image forming step of forming an image according to the image information generated in the light receiving step on a sheet using a color material, and when it is determined in the determining step that the fluorescence intensity exceeds a predetermined threshold value The image formation for forming an image by applying a color material containing a fluorescent material to at least a background area where the original image is not formed while at least applying a colored color material to an area corresponding to the original image Step and
Copying method characterized by having a.

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