JP2007116541A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conveniently and well read an object to be imaged having metallic gloss. <P>SOLUTION: A copier has a liquid crystal sheet on a platen glass, and this liquid crystal sheet is switched between a state (diffusion state) where a voltage is applied to disperse a light, and a state (transmissive state) where the light is transmitted. The copier generates image data for determination by executing scanning after bringing the liquid crystal sheet into a diffusion state (steps S1, S2), and generates image data indicating color information by executing scanning after bringing the liquid crystal sheet into a transmissive state (steps S3, S4). The copier determines the presence or absence of a metallic gloss region, based on the difference between the image data for determination and the image data indicating color information (step S5), and if the metallic gloss region exists (YES in step S5), an image is formed on the metallic gloss region using a toner of a metallic color. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that generates image data representing an object to be imaged, and more particularly to a technique for satisfactorily reading an object to be imaged having a metallic luster.

  In general, it is difficult to scan an object to be picked up with metallic luster using an image reading device and obtain image data representing this. This is because, in a general image reading apparatus, image data is generated based on diffuse reflected light when the object to be imaged is irradiated with light from a predetermined angle. Reflected light on the surface of an object is divided into a “specular reflection component” that reflects at an angle equal to the incident angle of incident light, and a “diffuse reflection component” that reflects at all angles. The light contains a lot of specular reflection components and a slight diffuse reflection component. Therefore, even when trying to read such an object to be imaged, the diffuse reflection component is insufficient, resulting in a dark (low brightness) image, and the object to be imaged cannot be expressed faithfully.

Therefore, various efforts have been made so far to read an object to be imaged with a metallic luster well. For example, in Patent Document 1, a document is read in a state where a sheet (reflected light control member) for increasing irregular reflection is inserted between the document table and the document, and image data generated at this time and a normal state (sheet) The region having the metallic luster is discriminated by using image data generated in a state where the original is read without inserting the.
JP 2005-101726 A

  However, in the case of the technique described in Patent Document 1 described above, the user himself / herself is required to perform an operation of inserting the reflected light control member. If such an operation is performed each time a document is read, a great burden is imposed on the user. In addition, since it is necessary to remove the document once in order to insert the reflected light control member, there is a problem that the position of the document is likely to be shifted before and after insertion, and accurate reading cannot be performed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for easily and satisfactorily reading an object to be picked up having a metallic luster.

  In order to achieve the above-described object, an image reading apparatus according to the present invention includes an illuminating unit that irradiates light to an object to be imaged, and light reflected by the object to be imaged among light irradiated by the illuminating unit. A light scattering means for scattering, a light scattering means for varying the degree of scattering, and a light receiving means for receiving scattered light from the light scattering means and outputting image data corresponding to the received scattered light. Prepare. According to this image reading apparatus, since the degree of scattering of the reflected light can be changed by the light scattering means, reading according to the metallic luster of the object to be imaged can be performed. For example, when reading an image pickup object having a surface where the reflected light contains a lot of specular reflection components, that is, an image pickup object having a metallic luster, the degree of scattering of the reflected light (particularly specular reflection light) is increased. The light received by the light receiving means may be increased.

  In the present invention, a liquid crystal sheet can be used as the light scattering means. In this case, it is more preferable that the liquid crystal sheet has a configuration extending along the upper surface or the lower surface of a glass member such as platen glass.

  The present invention also provides switching means for controlling the voltage applied to the light scattering means to switch the light scattering means between the first state in which light is scattered and the second state in which light is not scattered. The structure further provided may be sufficient. In the first state, the degree of light scattering may be changed continuously or stepwise. In this way, various objects having various glossiness can be used as the object to be imaged.

  Further, the present invention compares the first image data output by the light receiving means in the first state with the second image data output by the light receiving means in the second state, and A configuration may be provided that includes a discriminating unit that discriminates an area where the difference in the image data exceeds a predetermined threshold value as a glossy area. In this way, it is possible to distinguish between a region having metallic luster and a region that is not so in the object to be imaged, and it is also possible to perform processing according to each region.

  The present invention can also be specified as an image forming apparatus including the above-described image reading apparatus. As an example of the image forming apparatus according to the present invention, an electrophotographic copying machine, which will be described later, can be cited. Of course, an image forming apparatus of another recording method can also be included.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, an electrophotographic copying machine will be described as an embodiment of the present invention. Note that, in the present embodiment, due to the configuration, an object to be imaged as an image reading target is assumed to be mainly a sheet-like object such as paper or a metal plate. However, the reading target in the present invention is not limited to such an object.

[1. Constitution]
FIG. 1 is a block diagram schematically showing a configuration of a copying machine 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 machine 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.

  FIG. 3 is a diagram showing the configuration of the platen glass 11 in more detail. The platen glass 11 includes glass plates 111 and 115, intermediate films 112 and 114, and a liquid crystal layer 113. The glass plates 111 and 115 are transparent glass members and have a predetermined width and depth. The intermediate films 112 and 114 are transparent film members made of polyester, and a conductive film made of ITO (Indium Tin Oxide) is formed on each of them. These conductive films function as transparent electrodes. The liquid crystal layer 113 is a film-like member in which microcapsules filled with nematic liquid crystal are dispersed. As the polymer serving as the base material of the liquid crystal layer 113, a material having a refractive index equivalent to the refractive index of the microcapsules when the liquid crystal is in an alignment state by applying a voltage is selected. Hereinafter, the intermediate film 112, the liquid crystal layer 113, and the intermediate film 114 are collectively referred to as “liquid crystal sheet 11a”. The liquid crystal sheet 11a extends with the same width and depth as the glass plates 111 and 115.

  A predetermined potential difference is given between the electrodes of the liquid crystal sheet 11a by a voltage application unit 50 described later. In a state where a voltage is applied, the liquid crystal contained in the liquid crystal layer 113 is in an aligned state, so that the liquid crystal sheet 11a is in a state of transmitting light. On the other hand, in a state where there is no potential difference between the electrodes, the liquid crystals included in the liquid crystal layer 113 are in an irregular state, and thus the liquid crystal sheet 11a is in a state of scattering light. The relationship between the parallel light transmittance and haze ratio of the liquid crystal sheet 11a and the potential difference is, for example, as shown in FIG. In the figure, the unit of the transmittance Tp and the haze rate Hz is “%”, and the unit of the applied voltage V is “V (effective value)”.

  The platen cover 12 is provided so as to cover the platen glass 11 and blocks the external light to facilitate reading of the object to be imaged 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 light source having high color rendering properties such as a xenon fluorescent lamp or a tungsten halogen lamp, and irradiates the object to be imaged O with light having a predetermined intensity. The mirror 132 further reflects the reflected light from the object to be imaged O and forms an optical path (one-dot chain line in the figure) for guiding this light to the half-rate carriage 14. Note that light incident on the mirror 132 is light reflected at a reflection angle of approximately 0 ° with respect to the reflection surface of the object to be imaged O, and most of the light is a diffuse reflection component. 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 object to be imaged 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 an optical path connecting the mirror 142 and the line sensor 16, and images light from the object to be imaged O at the position of the line sensor 16. The line sensor 16 splits and receives the reflected light into, for example, red (R), green (G), and blue (B) light, and photoelectrically converts each of the three colors, a CCD (Charge Coupled Device) image sensor. And outputs an image signal corresponding to the intensity of the received light.

  Next, the configuration of the image forming unit 20 will be described. 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. A primary fixing mechanism 27, a switching mechanism 28, and a secondary fixing mechanism 29.

  Each of the sheet feeding trays 21 stores a sheet of a predetermined size and supplies the sheet in accordance with image formation. Here, the sheet is a sheet normally used in image formation such as a so-called PPC (Plain Paper Copier) sheet, but if necessary, a sheet of a material other than paper or paper whose surface is coated with resin or the like is used. Can be used. The transport roll 22 forms a transport path for transporting the sheet 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 sheet 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, development units 234, 235, 236 and 237, and a primary transfer roll 238. 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 having a predetermined potential on the surface thereof. The developing units 234, 235, 236, and 237 store toners of different colors and generate a predetermined potential difference (developing bias) between the surface of the photosensitive drum 231 and are formed on the surface of the photosensitive drum 231 by the potential difference. A toner image is formed by attaching toner to the electrostatic latent image thus formed. The developing units 234 to 237 constitute a so-called rotary type developing device. The primary transfer roll 238 generates a predetermined potential difference (primary transfer bias) at a position where the intermediate transfer belt 24 faces the photosensitive drum 231, and transfers the toner image onto the surface of the intermediate transfer belt 24 by this potential difference.

The toners stored in the developing units 234, 235, 236, and 237 are yellow (Y), gold, and silver, respectively, and a transparent toner. Here, the gold and silver toners are so-called metallic toners. The transparent toner is a toner that does not contain a color material. For example, a low molecular weight polyester resin is externally added with SiO ₂ (silicon dioxide) or TiO ₂ (titanium dioxide). The surface of the image formed by the transparent toner has increased smoothness and further gloss.

  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 again, 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, 231b, 231c, and 231d, and moves the toner image to transfer (secondary transfer) to a sheet. The secondary transfer roll 25 and the backup roll 26 generate a predetermined potential difference (secondary transfer bias) at a position where the intermediate transfer belt 24 faces the sheet, and transfer the toner image onto the sheet. The primary fixing mechanism 27 includes a roll member for heating and pressing the sheet, and fixes the toner image transferred on the surface of the sheet. The switching mechanism 28 changes the sheet conveyance path according to the type of toner image formed on the surface of the sheet. Specifically, the switching mechanism 28 conveys a sheet whose toner image contains transparent toner in the direction of arrow R in the figure, and conveys and discharges other sheets in the direction of arrow L in the figure. Let

  The secondary fixing mechanism 29 includes a fixing belt 291, a heater 292, and a heat sink 293. The secondary fixing mechanism 29 further applies heat to the sheet once heated and pressure-fixed in the primary fixing mechanism 27 by the heater 292 to re-melt the toner. Then, the secondary fixing mechanism 29 cools the sheet with the heat sink 293 while keeping the sheet in close contact with the smooth fixing belt 291 and fixes the toner. By performing such a fixing process, a toner image with a smooth surface and high glossiness can be formed.

  The configurations of the image reading unit 10 and the image forming unit 20 are as described above. Next, another configuration of the copying machine 100 will be described with reference to the block diagram of FIG. The copying machine 100 includes a control unit 30, a storage unit 40, a voltage application 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 machine 100 is controlled. Note that the control unit 30 according to the present embodiment performs a predetermined process such as AD conversion, shading correction, or color space conversion on the image signal generated by the image reading unit 10 and outputs image data corresponding to the image signal. Have The image data in this embodiment is data in which each pixel has a gradation value of 8 bits for each color of YMCK.

  The storage unit 40 is a large-capacity storage device such as an HDD (Hard Disk Drive), and stores various data including a program for operating each unit of the copying machine 100 described above. The voltage application unit 50 applies a voltage to be applied to the liquid crystal sheet 11 a in accordance with an instruction from the control unit 30. The operation unit 60 is an input device including a touch panel display and various buttons, and receives an input instruction from a user. 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 machine 100 can output image data supplied to the image forming unit 20 to an external device such as a computer as necessary.

[2. Operation]
With the above configuration, the copying machine 100 scans the object to be imaged O placed on the platen glass 11 to generate image data indicating the object to be imaged O, and generates an image based on the image data. Form on a sheet. In the following, a series of operations performed by the copying machine 100 from scanning of the object to be imaged O to image formation will be described along the flow of the flowchart shown in FIG.

  When the user instructs the start of the scanning process, the control unit 30 of the copying machine 100 first scans the entire object to be imaged O without applying a voltage to the liquid crystal sheet 11a (step S1). Since no voltage is applied, the liquid crystal sheet 11a is in a state of scattering light at this time. Based on the image signal generated at this time, the control unit 30 generates image data (hereinafter referred to as “discriminating image data”) for determining the metallic gloss region of the object to be imaged O, and stores it in the RAM (step S30). S2).

  Subsequently, the control unit 30 generates a potential difference between the electrodes of the liquid crystal sheet 11a via the voltage application unit 50, and scans the entire object to be imaged O in a state where a voltage is applied to the liquid crystal sheet 11a (step S3). The liquid crystal sheet 11a to which voltage is applied is in a state of transmitting light. Based on the image signal generated at this time, the control unit 30 generates image data representing the color information of the surface of the object to be imaged O and stores it in the RAM (step S4).

  If two image data are produced | generated, the control part 30 will compare these image data for every pixel, and will determine the presence or absence of a metallic luster area | region (step S5). In this determination processing, for example, it is determined whether or not there are continuously more than a predetermined number of pixels that exceed a threshold value for which the difference between the image data representing the color information and the image data for determination is determined. A positive region is determined to be a metallic gloss region.

  When it is determined in the above-described determination processing that a glossy area exists (step S5; YES), the control unit 30 supplies image data representing color information and information about the glossy area to the image forming unit 20, and these An image is formed on the basis of (Step S6). The control unit 30 instructs the image forming unit 20 to add metallic toner to the glossy region, and instructs yellow, magenta, cyan, and black toner to the other regions. give. Note that which of the metallic color toners to select may be determined based on image data representing color information. For example, if the color information of the image data in the area determined to be a metallic glossy area is close to white, silver toner is applied. If the color information of the image data in the area determined to be a metallic glossy area is close to yellow, gold toner is applied. Can be given.

  On the other hand, when it is determined in the above-described determination process that the metallic gloss region does not exist (step S5; NO), the control unit 30 supplies the image data representing the color information to the image forming unit 20, and based on this. Then, an image is formed (step S7). That is, the image forming unit 20 forms an image using yellow, magenta, cyan, and black toner for all regions.

  By forming an image as described above, the copying machine 100 according to the present embodiment can appropriately determine a metallic glossy area and reproduce the area with metallic toner. According to the copying machine 100 of the present embodiment, two scans can be performed without moving the object to be imaged O, so that a positional deviation occurs between the image data for determination and the image data representing the color information. There is no fear. Further, since the transmission / scattering state of the liquid crystal sheet 11a can be changed by applying a voltage, it is not necessary for the user to insert a reflection light control member.

[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, it has been described that the liquid crystal sheet 11a is in the scattering state by the voltage application unit 50 giving a predetermined potential difference. However, the transmittance of the liquid crystal sheet 11a continuously changes as shown in FIG. In this case, it is possible to change the degree to which the liquid crystal sheet 11a scatters light by appropriately changing the applied voltage. By utilizing this, for example, when scanning an object to be imaged with high glossiness, the degree of light scattering is increased, and when scanning an object to be imaged with low glossiness, the degree of light scattering is decreased. You may do it. In this way, it is possible to perform scanning in an optimal state corresponding to each object to be imaged. In addition, it is good also as a structure which determines several voltages to apply beforehand and makes a user select this as a mode.

  Further, in the above-described embodiment, it has been described that the image of the metallic gloss area is formed with the metallic toner, but the metallic toner is applied to the entire metallic gloss area, and the glossiness area of the metallic gloss area is high. On the other hand, transparent toner may be applied according to the glossiness. In the above-described embodiment, only gold and silver toners are shown as metallic color toners, but other metallic colors may be employed.

  Furthermore, the form of image formation may be different depending on whether it has a metallic gloss region or not. For example, when forming an image that does not have a metallic glossy area, the fixing process is performed using only the primary fixing mechanism 27, and the sheet is conveyed in the direction of arrow L in FIG. When forming an image having a metallic glossy area, after the fixing process by the primary fixing mechanism 27, the switching mechanism 28 causes the sheet to be conveyed in the direction of arrow R in FIG. The fixing process can be performed. Alternatively, the fixing speed and the fixing temperature may be different depending on whether the metallic gloss region is provided or not.

  Moreover, in the above-mentioned embodiment, although the liquid crystal sheet 11a was the structure pinched | interposed into the two glass plates 111 and 115, it is not limited to such a structure. For example, the structure supported by the supporting member on the upper surface or lower surface of one glass plate may be sufficient. The platen glass is generally a glass plate, but of course, it may be a light-transmitting plate member (acrylic plate or the like) made of a material different from glass.

  In addition, the structure of the means to scatter light is not restricted to the liquid crystal sheet 11a mentioned above. It is sufficient that the light scattering means can change the light transmission / scattering state in accordance with the applied voltage. Therefore, for example, a liquid crystal sheet made of cholesteric liquid crystal or a liquid crystal sheet made of so-called guest / host liquid crystal can be used.

  Further, in the above-described embodiment, the image data for discriminating the metallic gloss region is generated from the image signal received by the same optical path as the image data representing the color information. Is also possible. For example, the image data for determining the metallic gloss region may be generated from an image signal received by an optical path from the specular reflection direction (that is, the direction in which the reflection angle with respect to the reflection surface is equal to the incident angle). Since the intensity of the reflected light from the specular reflection direction has a strong correlation with the glossiness of the object to be imaged, it is an effective method to use the image data generated by the reflected light for the determination of the metallic glossy area. In this case as well, when scanning an object to be imaged with high glossiness, it is preferable to increase the degree of light scattering by the liquid crystal sheet.

  When this method is used, it is also possible to use the process of reading the reflected light from the specular reflection direction as a pre-scan, and determine the presence or absence of the metallic gloss region by this pre-scan. For example, if there is a region where the brightness of image data generated by reflected light from the specular reflection direction is higher than a predetermined threshold, this region can be regarded as a metallic gloss region.

1 is a block diagram schematically showing a configuration of a copying machine according to an embodiment of the present invention. FIG. 2 is a diagram more specifically showing a configuration of a copying machine. It is the figure which showed the structure of the platen glass of a copying machine. It is the figure which showed the relationship between the transmittance | permeability of the liquid crystal sheet of a platen, and an electrical potential difference. FIG. 2 is a diagram illustrating a configuration of a primary transfer unit of a copying machine. 5 is a flowchart showing processing performed by a copying machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Copy machine, 10 ... Image reading part, 11 ... Platen glass, 11a ... Liquid crystal sheet, 111, 115 ... Glass plate, 112, 114 ... Intermediate film, 113 ... Liquid crystal layer, 12 ... Platen cover, 13 ... Full-rate carriage, DESCRIPTION OF SYMBOLS 14 ... Half-rate carriage, 15 ... Imaging lens, 16 ... Line sensor, 20 ... Image formation part, 21 ... Paper feed tray, 22 ... Conveyance roll, 23, 23a, 23b, 23c, 23d ... Primary transfer unit, 24 ... Intermediate transfer belt, 25 ... secondary transfer roll, 26 ... backup roll, 27 ... primary fixing mechanism, 28 ... switching mechanism, 29 ... secondary fixing mechanism, 30 ... control unit, 40 ... storage unit, 50 ... voltage application unit, 60 ... operation unit, 70 ... communication unit

Claims (6)

Illuminating means for irradiating the imaged object with light;
A light scattering means for scattering light reflected by the object to be imaged among the light irradiated by the illumination means, and a light scattering means for varying the degree of scattering;
An image reading apparatus comprising: light receiving means for receiving scattered light from the light scattering means and outputting image data corresponding to the received scattered light.   The image reading apparatus according to claim 1, wherein the light scattering unit is a liquid crystal sheet. A plate-like glass member for placing the object to be imaged;
The image reading apparatus according to claim 2, wherein the liquid crystal sheet extends along an upper surface or a lower surface of the glass member. The light scattering means is a light scattering means for changing the degree of scattering according to an applied voltage,
And a switching unit that controls a voltage applied to the light scattering unit and switches the light scattering unit between a first state in which light is scattered and a second state in which light is not scattered. The image reading apparatus according to claim 1. The first image data output by the light receiving means in the first state is compared with the second image data output by the light receiving means in the second state, and there is a difference between these image data. The image reading apparatus according to claim 4, further comprising: a determination unit that determines that an area exceeding a predetermined threshold is a glossy area.   An image forming apparatus comprising the image reading apparatus according to claim 1.

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