JP2013137208A - Spectral characteristic acquisition device, image evaluation device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectral characteristic acquisition device and an image evaluation device that accurately evaluate colors possessed by an object such as a coloring material, and an image forming apparatus.SOLUTION: A spectral characteristic acquisition device includes light irradiation means 101 for irradiating a medium 10 with light, area dividing means 102 for dividing the light radiated from the light irradiation means and transmitted the medium into areas, light guide means 103 for guiding the light divided into areas by the area dividing means; spectroscopic means 104 for dispersing the light guided by the light guide means; and light-receiving means 105 for receiving the light dispersed by the spectroscopic means. The spectral characteristic acquisition device acquires spectral characteristics from the light transmitted the medium.

Description

  The present invention relates to a spectral characteristic acquisition device, an image evaluation device, and an image forming device.

  As an image forming method employed in an image forming apparatus such as a printer or a copying machine, various methods such as an electrophotographic method, an ink jet method, and a thermal method are known. In recent years, in the field of production printing, both sheet-fed machines and continuous book machines have been digitized, and many different products have been put on the market.

  In such an image forming apparatus, multi-dimensional, high-definition, and high-density images have been developed in the transition from monochrome printing to color printing, and personal preference for high-quality photo printing, catalog printing, receipts, etc. Service forms for consumers are diversifying, such as advertisement placement corresponding to. Accordingly, there is a growing demand for image quality improvement and color reproducibility for image forming apparatuses in accordance with diversified service forms.

  For example, in the electrophotographic system, a technology that stabilizes the toner supply amount by installing a density sensor that detects the toner density before fixing on the intermediate transfer member or the photosensitive member has been put to practical use as a technology that supports high image quality. ing. Further, as a technique for improving color reproducibility, for example, a technique for performing calibration by outputting a color patch and performing color measurement at one or more points with a spectrometer has been put into practical use. In such a technique, it is preferable to be able to deal with image fluctuations between pages or within a page of a medium such as paper, and it is desirable to measure spectral characteristics over the entire width of the medium.

  In addition to the demand for higher image quality, for example, in addition to cyan, yellow, magenta, and black, which are commonly used for image formation, multicolorization using different color materials and special color materials that express unique colors, etc. Correspondence to is also important. Even when color materials are evaluated for multi-coloring, spectral characteristics are measured over the full width of the medium to separate the influence of the surface condition of the medium and variations in the image forming process from the characteristic variations inherent to the color material. Therefore, it is desirable to evaluate the color material and the like.

  Therefore, as a technique for measuring and evaluating an image on a medium with a full width, for example, Patent Document 1 discloses a measurement device that can move above a measurement table to scan a pixel line to be measured, and a line sensor. There has been proposed a measuring device having a measuring device provided and a processing device for processing and evaluating a measurement signal from the measuring device.

  For example, Patent Document 2 discloses a full-width array light image including a long irradiation array including LED illumination sources that emit a plurality of different colors over the entire width of a moving print medium sheet, and a long array including a multi-color photodetector. A full-width array spectrophotometer has been proposed that has a scanning bar and performs full-width scanning color analysis of print media sheets.

  However, when evaluating a color material or the like from an image fixed on a medium such as paper, the color of the paper becomes the brightest color, and from this, for example, the color is determined by subtractive color mixing. Will be affected by the color of the. In addition, the reflection state of light varies depending on the surface state of the paper, and the color information mainly affects the brightness, so the color material has a color from the reflected light such as an image fixed on a medium such as paper. Individual measurements with high accuracy may be difficult.

  The present invention has been made in view of the above, and an object of the present invention is to provide a spectral characteristic acquisition apparatus capable of evaluating a color of a color material formed on a medium such as paper with high accuracy.

  The spectral characteristic acquisition apparatus according to an aspect of the present invention includes a light irradiating unit that irradiates light to a medium, a region dividing unit that divides the light irradiated from the light irradiating unit and transmitted through the medium, and the region dividing A light guide unit that guides the light divided into regions by the unit, a spectroscopic unit that splits the light guided by the light guide unit, and a light receiving unit that receives the light split by the spectroscopic unit. Then, spectral characteristics are acquired from the light transmitted through the medium.

  According to the embodiment of the present invention, for example, it is possible to provide a spectral characteristic acquisition device that can accurately evaluate the color of a color material formed on a medium such as paper.

It is the schematic which shows the structural example of the spectral characteristic acquisition apparatus which concerns on 1st Embodiment. It is a figure which illustrates typically pixel structure of a line sensor concerning a 1st embodiment. It is the photograph which shows the state which looked at the light which injects into a line sensor from the entrance plane side. It is a figure explaining the structural example of the diffraction element with respect to the pixel of the line sensor which concerns on 1st Embodiment. It is a photograph which illustrates the state which looked at the light which injects into the line sensor which concerns on 1st Embodiment from the entrance plane side. It is a figure which illustrates the spectral distribution of the toner image used for simulation. It is a figure which illustrates a simulation result. It is a figure which illustrates the measurement result of the spectral distribution of the image on a different medium. It is the schematic which shows the other structural example of the spectral characteristic acquisition apparatus which concerns on 1st Embodiment. It is the schematic which shows the structural example of the spectral characteristic acquisition apparatus which concerns on 2nd Embodiment. It is the elements on larger scale which illustrate the optical path of the spectral characteristics acquisition device concerning a 2nd embodiment. It is a figure which shows the example of the measurement result of the light quantity in the width direction of a medium in the case shown in FIG. It is a figure which shows the structural example of the lens array and aperture array which concern on 2nd Embodiment. It is the elements on larger scale which illustrate the optical path of the spectral characteristic acquisition apparatus in the composition of Drawing 13 (b). It is a figure which shows the example of the measurement result of the light quantity in the width direction of the medium in the case shown in FIG. It is the schematic which shows the structural example of the spectral characteristic acquisition apparatus which concerns on 3rd Embodiment. It is a figure which shows the structural example of the medium fixing means and lens array which concern on 3rd Embodiment. It is a figure which shows the other structural example of the medium fixing means and lens array which concern on 3rd Embodiment. It is the schematic which shows the other structural example of the spectral characteristic acquisition apparatus which concerns on 3rd Embodiment. It is a side view which shows the structural example of the image evaluation apparatus which concerns on 4th Embodiment. It is the schematic which shows the structural example of the image forming apparatus which concerns on 5th Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted. In the present application, the spectral characteristic refers to the amount of diffuse reflected light expressed as a function of wavelength, and the spectral characteristic includes spectral reflectance.
[First Embodiment]
FIG. 1 is a schematic diagram illustrating a configuration example of a spectral characteristic acquisition apparatus 1 according to the first embodiment. In the following description, the X direction is the pixel array direction of the light receiving means 105, the Y direction is the direction orthogonal to the pixel array direction on the light receiving surface of the light receiving means 105, the Z direction is orthogonal to the pixel array direction of the light receiving means 105, and the measurement object The direction perpendicular to the surface of

  The spectral characteristic acquisition apparatus 1 includes a line illumination light source 101 as a light irradiation unit, an aperture array 102 as a region dividing unit, an optical system 103 as a light guiding unit, a diffraction element 104 as a spectral unit, and a line sensor 105 as a light receiving unit. Have

  The line illumination light source 101 as the light irradiating means irradiates a transparent medium 10 such as an OHP film with linear light spreading in the width direction (X direction). On the surface of the medium 10, an image made of, for example, toner or ink, which is an object for measuring spectral characteristics, is formed.

  As the line illumination light source 101, for example, a white LED (Light Emitting Diode) array having an intensity in almost the entire visible light region can be used. Further, for example, a fluorescent lamp such as a cold cathode tube or a lamp light source can be used. However, it is preferable that the line illumination light source 101 emits light in a wavelength region necessary for spectroscopy and can illuminate uniformly over the entire measurement region. Further, the configuration in which the cylindrical lens is provided between the line illumination light source 101 and the medium 10 can improve the S / N ratio by converging the light amount on the line.

  The opening array 102 is, for example, a pinhole array or a slit array, and includes a plurality of openings formed in a row and is disposed in the vicinity of the medium 10. The aperture array 102 is a light-shielding portion that blocks light at portions other than the aperture, and divides the light that is irradiated by the line illumination light source 101 and transmitted through the medium 10 into regions. As the opening array 102, for example, a metal or black resin material in which openings are formed, a glass or transparent resin or the like obtained by patterning and applying a metal film or black resin, or the like can be used. The shape of the opening is not limited to a circle and a rectangle, and may be another shape such as an ellipse. In addition, a plurality of openings may be arranged in two or more rows.

  The optical system 103 includes a plurality of lenses, and has a function as an image forming unit that forms an image of the light beam that has passed through the aperture array 102 on the light receiving surface of the line sensor 105 via the diffraction element 104. As the optical system 103, for example, a lens used for a general scanner optical system or an industrially used lens for a line sensor can be used. The broken line shown in FIG. 1 schematically shows a typical optical path after the light irradiated on the OHP film 10 is diffusely reflected.

  The line sensor 105 includes a plurality of pixels, and has a function as a light receiving unit that acquires a diffuse reflection light amount of a predetermined wavelength band incident through the diffraction element 104. As the line sensor 105, for example, a metal oxide semiconductor device (MOS), a complementary metal oxide semiconductor device (CMOS), a charge coupled device (CCD), a photo diode array (PDA), or the like can be used.

  FIG. 2 is a diagram schematically illustrating the pixel structure of the line sensor 105. In FIG. 2, the line sensor 105 has a pixel structure in which a plurality of pixels are arranged in a line in the X direction. The line sensor 105 is a spectroscopic sensor array in which a plurality of first spectroscopic sensors 105a, second spectroscopic sensors 105b, third spectroscopic sensors 105c, and the like, each having a group of N pixels arranged together, are arranged. Yes. The first spectroscopic sensor 105a, the second spectroscopic sensor 105b, the third spectroscopic sensor 105c, and the like have N pixels that receive light having different spectral characteristics. Note that the plurality of pixels included in the line sensor 105 is not limited to a pixel structure arranged in a line, and may be arranged in two or more lines.

  The light from one aperture of the aperture array 102 is incident on N pixels of one spectroscopic sensor of the line sensor 105, and the N of the spectroscopic sensors of the aperture array 102 and the line sensor 105 are aligned. The pixel is in an imaging relationship.

For the diffraction element 104, for example, a sawtooth shape formed on a transparent substrate at a predetermined interval is preferable because it can enhance the + 1st order diffracted light, but other shapes such as a stepped shape can also be used. When the interval of the sawtooth shape of the diffractive element 104 is p, light having a wavelength λ incident on the diffractive element 104 at an angle θ _in is diffracted to an angle θ _m expressed by the equation (1). In Expression (1), m is the diffraction order by the diffraction element 104, and can take a positive or negative integer value.

The wavelength dependency of the diffraction angle theta _m of formula (1), it is possible to incident light having different spectral characteristics to N pixels.

  For example, when the pixel period of the line sensor 105 is 10 μm, the period of the diffraction element 104 is 10 μm, and the distance between the diffraction part of the diffraction element 104 and the line sensor 105 is 2 mm, the visible light is split into approximately 6 pixels and incident. can do.

  Here, when the diffraction element 104 diffracts light in the pixel arrangement direction (X direction) of the line sensor 105, the light beam is a 0th-order light, a second-order diffraction image, a diffraction image transmitted through an adjacent opening, or the like. There may be overlap on the sensor 105. In such a case, the crosstalk shown in FIG. 3 occurs, making it difficult to obtain accurate spectral characteristics.

  Therefore, as shown in FIGS. 4 and 5, for example, the diffraction element 104 is rotated in a plane perpendicular to the optical axis of the optical system in FIG. 1, or the angle of the teeth of the diffraction element 104 is set as appropriate. The light diffraction direction and the arrangement direction of the pixels of the line sensor 105 are configured to have a predetermined angle β. With this configuration, it is possible to obtain spectral characteristics by eliminating crosstalk of diffraction images. 4 and 5 are examples in which the diffraction element 104 is tilted by 10 degrees.

  As described above, the line sensor 105 according to the first embodiment includes the first spectroscopic sensor 105a, the second spectroscopic sensor 105b, the third spectroscopic sensor 105c, and the like, each of which includes N pixels arranged as a group. This is a multiband spectroscopic sensor arranged in plural.

  In multiband spectroscopy, the more the number N of pixels that each spectral sensor has, the more detailed measurement results of the spectral distribution can be obtained, which is preferable. However, when the number of pixels of the line sensor 105 is constant, the number of spectral sensors that can be arrayed decreases as the number of N increases. Therefore, it is preferable that the spectral characteristic acquisition apparatus 1 includes processing (spectral estimation processing) in which the number of N is minimized and spectral distribution is estimated by estimation means such as Wiener estimation. Many methods have been proposed for the spectral estimation processing, and are described in detail, for example, in “Non-patent literature“ Analysis and evaluation of digital color images: University of Tokyo Press: p154-157 ””.

  An example of a technique for estimating the spectral distribution from the output vi from one spectroscopic sensor will be shown below. From the row vector v storing the signal outputs vi (i = 1 to N) from the N pixels constituting one spectroscopic sensor and the conversion matrix G, the spectral reflectance (for example, 400 to 700 nm) of each wavelength band. (31 of 10 nm pitch) is stored as a row vector r expressed by the equation (2).

As shown in the equations (3) to (5), the transformation matrix G includes a matrix R that stores the spectral distributions of a large number (n) of samples whose spectral distributions are known in advance, and the spectral samples obtained by the spectral characteristic acquisition apparatus 1. From the matrix V storing v when measured, it is obtained by minimizing the square norm ‖ · ‖2 of the error using the least square method.

The regression coefficient matrix G of the regression equation from V to R, where V is the explanatory variable and R is the objective variable, is obtained by using the Moore-Penrose generalized inverse matrix that gives the least-squares norm solution of the matrix V. Is calculated as follows.

Here, the superscript T represents the transpose of the matrix, and the superscript -1 represents the inverse matrix. By storing G obtained by Expression (6), the spectral distribution r of an arbitrary object is estimated by taking the product of the transformation matrix G and the signal output v during actual measurement.

  For example, a toner image output by an electrophotographic image forming apparatus is read by the spectral sensor array in the first embodiment to estimate a spectral distribution, and a simulation is performed to calculate a color difference that is an estimation error from the estimated spectral distribution. It was. In the simulation, the color difference (ΔE) between the side color result when the value of N is changed and the side color result obtained from a more detailed spectroscopic device is obtained.

  FIG. 6 is a diagram illustrating the spectral distribution of the toner image used in the simulation, and FIG. 7 is a diagram illustrating the simulation result. From the results shown in FIG. 7, it can be seen that as N increases, the measurement accuracy improves, and when N is 6 or more, there is no significant difference in the error of the estimated value. This result changes depending on the object to be measured, the spectral distribution of the signal received by the sensor, etc., but when the number of N is 6 or more to color the output result of the toner of the image forming apparatus, etc. The error of the spectral estimation value is sufficiently small, indicating that a suitable spectral sensor array can be realized.

  FIG. 8 shows an example of the measurement result of the spectral distribution of images on different media. FIGS. 8A and 8B show the results of forming the same image on different media and measuring the spectral characteristics from the respective media using the spectral characteristic acquisition apparatus 1. As shown in FIG. 8, when different media are used, different spectral distributions are measured even for the same image due to the color of the media itself and the difference in surface condition.

  Therefore, by measuring and storing the spectral distribution of the medium before forming the image and canceling the color component of the medium from the spectral distribution of the medium after forming the image, it is possible to acquire the spectral characteristics with higher accuracy. It becomes possible.

  As shown in FIG. 9, when evaluating an image on a medium such as an OHP film, for example, a medium fixing means 106 formed of, for example, glass is installed to suppress a change in posture of the medium 10 and the like. It is effective.

  As described above, in the spectral characteristic acquisition device 1 according to the first embodiment, for example, a color included in an object such as an image by acquiring spectral characteristics from transmitted light such as an image formed on a transparent medium. Colors of materials etc. can be evaluated with high accuracy.

[Second Embodiment]
Next, a second embodiment will be described based on the drawings. FIG. 10 is a schematic diagram illustrating a configuration example of the spectral characteristic acquisition apparatus 2 according to the second embodiment.

  As shown in FIG. 10, the spectral characteristic acquisition apparatus 2 includes a line illumination light source 101 as a light irradiation unit, an aperture array 102 as a region dividing unit, an optical system 103 as a light guide unit, a diffraction element 104 as a spectral unit, A line sensor 105 as a light receiving unit and a lens array 107 as an imaging unit are included.

  In the spectral characteristic acquisition device 2, among the light emitted from the line illumination light source 101, the light transmitted through the medium 10 is collected by the lens array 107 and imaged on the aperture array 102, and the light flux that has passed through the aperture array 102. Is condensed on the optical system 103, diffracted by the diffraction element 104, and formed on the light receiving surface of the line sensor 105.

  The lens array 107 has a function of forming an image or the like formed on the medium 10 on the aperture array 102 as described above. However, it is not always necessary to form an image accurately on the aperture array 102, and it may be in a defocused state on the aperture array 102. In this embodiment, a configuration using a SELFOC (registered trademark) lens array is shown, but instead of the SELFOC (registered trademark) lens array, a microlens array, other equal-magnification imaging optical elements, and a plurality of lenses are used. An imaging lens can be used.

  In this way, by providing the lens array 107 between the medium 10 and the aperture array 102, light including color information of the color material of the measurement object on the medium is once coupled to the aperture array 102 in the middle of the optical system. As a result, the clearance between the measurement object and the measurement device can be secured.

  FIG. 11 is a partially enlarged view illustrating the optical path of the spectral characteristic acquisition device 2 according to the second embodiment.

  As illustrated in FIG. 11, when a SELFOC (registered trademark) lens array is used as the lens array 107, the optical system 103 may be an aperture array depending on the specifications of the optical system 103 due to the straightness of the light beam passing through the lens. In some cases, the diffused light that has passed through 102 cannot be completely captured. In addition, a light / dark distribution may occur in the amount of light due to the difference between the lens interval of the lens array 107 and the aperture interval of the aperture array 102 in the X direction in the figure.

  FIG. 12 shows an example of the measurement result of the light quantity in the width direction of the medium in the case shown in FIG. As shown in FIG. 12, when the optical system 103 cannot capture the diffused light that has passed through the aperture array 102, the periphery of the medium 10 cannot be measured, and the measurement range becomes narrow.

  Therefore, for example, by configuring the lens array 107, the aperture array 102, and the like as shown in FIG. 13, the surface of the medium 10 can be measured over a wide range. FIG. 13 is a diagram illustrating a configuration example of the lens array 107 and the aperture array 102 as viewed from the side from which light is emitted from the apertures of the aperture array 102. In the drawing, only the openings of the opening array 102 are shown, and the light shielding portion is omitted, and a plurality of lenses and openings are further arranged in the X direction in the drawing.

  As shown in FIG. 13, first, the lenses 107a, 107b, 107c, etc. of the lens array 107 and the openings 102a, 102b, 102c, etc. of the aperture array 102 are combined in pairs. Here, the position of the opening is configured to be shifted or matched with respect to the center of the lens according to the measurement target position (FIG. 13A), or the position at which the transmitted light from the measurement target enters the lens. Is configured to be limited by, for example, the slit 108 (FIG. 13B).

  FIG. 14 is a partially enlarged view illustrating the optical path of the spectral characteristic acquisition device 2 in the configuration of FIG. FIG. 15 is a diagram illustrating an example of a measurement result of the light amount in the width direction of the medium 10 in the case illustrated in FIG. 13.

  As shown in FIG. 14, the center of the lens of the lens array 107 and the opening of the aperture array 102 are configured as a pair, and a slit 108 is provided to limit the light incident on the lens. It becomes possible to capture all the transmitted light from. Further, as shown in FIG. 15, the entire range in the width direction of the medium 10 can be measured.

  As described above, in the spectral characteristic acquisition apparatus 2 according to the second embodiment, by providing the lens array 107 between the medium 10 and the aperture array 102, light is imaged once in the middle of the optical system. The clearance between the optical system 10 and the optical system can be secured. Therefore, the degree of freedom in designing the optical system 103 and the like can be improved. Also in such a configuration, the lens of the lens array 107 and the aperture of the aperture array 102 are configured as a pair, and for example, the center of the lens and the position of the aperture are arranged so as to be shifted according to the position of the measurement target. Alternatively, the measurement range of the medium 10 can be expanded by providing the slit 108.

[Third Embodiment]
Next, a third embodiment will be described based on the drawings. FIG. 16 is a schematic diagram illustrating a configuration example of the spectral characteristic acquisition apparatus 3 according to the third embodiment.

  As shown in FIG. 16, the spectral characteristic acquisition device 3 includes a line illumination light source 101 as a light irradiating means, an aperture array 102 as a region dividing means, an optical system 103 as a light guiding means, a diffraction element 104 as a spectral means, It has a line sensor 105 as a light receiving means, a medium fixing means 106 for fixing and holding the medium, and a lens array 107 as an imaging means.

  The medium fixing means 106 is formed of a transparent material such as glass, and holds the medium 10 in close contact. The medium fixing means 106 has a fixing member such as a clip that fixes and holds the end of the medium 10, for example, and corrects the posture of the medium 10. By providing the medium fixing means 106, it is possible to keep the distance between the medium 10 and the line illumination light source 101 uniform, and to prevent the measurement result from varying depending on the position of the medium 10.

  Although the lens array 107 can be configured separately from the medium fixing means 106, it is preferable that the lens array 107 and the medium fixing means 106 are integrally formed. By forming them integrally, the distance between the medium 10 and the lens array 107 can be kept constant, displacement of the optical system in the optical axis direction can be eliminated, and measurement accuracy can be improved.

  Here, as shown in FIG. 17, the medium fixing means 106 and the lens array 107 are preferably large enough to cover the entire medium 10, and the lens array 107 is preferably formed over the entire surface. In addition, as shown in FIG. 18, the lens array 107 is limited to one line or a plurality of lines in the width direction of the medium 10, and either the medium 10 or the spectral characteristic acquisition device 3 is moved to measure the entire surface of the medium 10. It can also be configured to do. In any configuration, it is possible to eliminate the positional deviation in the optical axis direction of the light beam transmitted through the medium 10.

  Further, as shown in FIG. 19, by providing a light shielding member 110 having a plurality of openings on the surface of the medium fixing unit 106 that fixes and holds the medium 10, the measurement target region is divided and adjacent to the medium 10. It is possible to reduce the influence received from the image to be generated and prevent an error from occurring. Further, by aligning the measurement target area of the medium 10 with the position of the opening of the light shielding member 110, it is possible to easily confirm which position on the medium 10 is being measured.

  As described above, according to the third embodiment, by providing the medium fixing means 106 that fixes and holds the medium 10, the distance between the medium 10 and the line illumination light source 101 is kept uniform, and the measurement accuracy is improved. Can do. Further, by forming the lens array 107 and the medium fixing means 106 as the imaging means integrally, the distance between the medium 10 and the lens array 107 is kept constant, and displacement of the optical system in the optical axis direction is eliminated. In addition, the measurement accuracy can be further increased.

[Fourth Embodiment]
In the fourth embodiment, an example in which an image evaluation apparatus is configured using a spectral characteristic acquisition apparatus will be described. FIG. 20 is a side view illustrating a configuration example of the image evaluation device 4 according to the fourth embodiment.

  The image evaluation apparatus 4 evaluates an image formed on the medium 10 by, for example, an electrophotographic image forming apparatus over the entire width. The image evaluation apparatus 4 is configured by arranging one or more spectral characteristic acquisition apparatuses 1 of the first embodiment in parallel in the width direction (X direction) of the medium 10.

  The image evaluation apparatus 4 includes an image evaluation unit 112 and a conveyance roller 111 that is a moving unit that moves the medium 10. The transport roller 111 transports the medium 10 in the Y direction in FIG. Note that the image evaluation apparatus 5 is configured to move the medium 10, but the image evaluation apparatus 4 may be configured to move relative to the medium 10. In addition to the transport roller, a transport belt or the like can be used as the moving means.

  The image evaluation unit 112 combines the outputs from the line sensor 105 to calculate side color data such as XYZ and L * a * b *, and evaluates the color of the image formed on the medium 10 with a plurality of colors. Have The image evaluation unit 112 can calculate spectral image data over the entire image forming unit of the medium 10 based on speed information from an encoder sensor that is known or mounted on the recording medium conveyance mechanism.

  In the image evaluation device 4, it is preferable that the image evaluation unit 112 compares the side color result obtained by the line sensor 105 with the master image, and extracts and displays the difference from the master image. As a result, the operator can easily perform comparison with the master image. Further, the master image may be configured so that a digital master image can be input from the outside, and the measurement result of a certain medium 10 measured by the image evaluation device 5 may be set as the master image.

  In addition, in the image evaluation apparatus 5, it can replace with the spectral characteristic acquisition apparatus 1 of 1st Embodiment, and can also use the spectral characteristic acquisition apparatus of 2nd or 3rd Embodiment.

  As described above, according to the fourth embodiment, by configuring the image evaluation apparatus using the spectral characteristic acquisition apparatus, the color of an object such as an image formed on the transported recording medium can be evaluated at high speed. It is possible to realize an image evaluation apparatus that can be performed in a simple manner.

[Fifth Embodiment]
In the fifth embodiment, an example of an image forming apparatus 5 having the image evaluation apparatus 4 of the fourth embodiment is shown. FIG. 21 is a diagram illustrating a configuration example of the image forming apparatus 5 according to the fifth embodiment.

  As shown in FIG. 21, the image forming apparatus 5 includes an image evaluation apparatus 4 according to the fourth embodiment, paper feed cassettes 501a and 501b, a paper feed roller 502, a controller 503, a scanning optical system 504, and a photosensitive. A body 505, an intermediate transfer body 506, a fixing roller 507, and a paper discharge roller 508 are formed to form an image on the surface of the medium 10.

  In the image forming apparatus 5, the medium 10 conveyed from the paper feed cassettes 501 a and 501 b by a guide (not shown) and the paper feed roller 502 is exposed to the photosensitive member 505 by the scanning optical system 504, and development is performed by applying a color material. Is done. The developed image is primarily transferred onto the intermediate transfer member 506 and then secondarily transferred from the intermediate transfer member 506 onto the medium 10.

  The image transferred onto the medium 10 is fixed by the fixing roller 507, and the image-formed medium 10 is discharged by the paper discharge roller 508. The image evaluation device 5 is installed at the subsequent stage of the fixing roller 507 in order to perform evaluation with an image formed on the recording medium 10.

  As described above, according to the fifth embodiment, by including the image evaluation device 4, the evaluation result of the image formed on the medium 10 is reflected in the image forming conditions in the development, transfer, fixing process, and the like. Therefore, it is possible to realize a highly reliable image forming apparatus that can always provide a high-quality image free from color fluctuations.

  Note that the spectral characteristic acquisition apparatus and the image evaluation apparatus according to the embodiment can evaluate spectral characteristics by acquiring spectral characteristics from an image printed on, for example, plastic other than paper, for example, authenticity of banknotes and credit cards. It is also possible to apply to an evaluation device that evaluates fake and types.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations shown here, such as combinations with other elements, etc., in the configurations described in the above embodiments. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

1-3 Spectral characteristic acquisition device 4 Image evaluation device 5 Image forming device 10 Medium 101 Line illumination light source (light irradiation means)
102 Aperture array (area dividing means)
103 Optical system (light guiding means)
104 Diffraction element (spectral means)
105 Line sensor (light receiving means)
106 Medium fixing means 107 Lens array (imaging means)
110 Shading member 111 Conveying roller (moving means)
112 Image evaluation means

Special table 2008-518218 gazette JP 2005-315883 A

Claims (6)

A light irradiation means for irradiating the medium with light;
Area dividing means for dividing the light irradiated from the light irradiation means and transmitted through the medium;
A light guiding means for guiding the light divided by the area dividing means;
A spectroscopic means for splitting the light guided by the light guide means;
A light receiving means for receiving the light split by the spectroscopic means;
A spectral characteristic acquisition device for acquiring spectral characteristics,
The spectral characteristic acquisition apparatus according to claim 1, wherein the light irradiation means transmits light to the medium. The spectral characteristic acquisition apparatus according to claim 1, further comprising an imaging unit that is provided between the medium and the region dividing unit and forms an image of the light transmitted through the medium on the region dividing unit. Having plate-like medium fixing means made of a transparent material for fixing and holding the medium;
The spectral characteristic acquisition apparatus according to claim 2, wherein the imaging unit is formed integrally with the medium fixing unit. The spectral characteristic acquisition apparatus according to claim 3, wherein the medium fixing unit includes a light shielding member having a plurality of openings on a surface for fixing and holding the medium. The spectral characteristic acquisition device according to any one of claims 1 to 4,
Moving means for moving one of the medium and the spectral characteristic acquisition device;
The spectral characteristic acquisition device evaluates the color of the object based on the spectral characteristic acquired from the object on the medium; and
An image evaluation apparatus comprising:   An image forming apparatus comprising the image evaluation apparatus according to claim 5.