JP5257170B2 - Gloss unevenness evaluation apparatus, gloss unevenness evaluation method, image forming apparatus, and recording medium - Google Patents

Description

  The present invention quantitatively measures uneven gloss on the surface of an object, which is used for image forming apparatuses such as copying machines, facsimiles, printers, and printing machines, and other surface states of metals and resins other than image forming. The present invention relates to a gloss unevenness evaluation device to be evaluated, a gloss unevenness evaluation method, such an image forming apparatus having such a gloss unevenness evaluation device, and a computer-readable recording medium storing a program for executing such a gloss unevenness evaluation method.

  In recent years, transparent toner has been used as a toner in image forming apparatuses such as copying machines, facsimiles, printers, and so-called electrophotographic systems, and other image forming apparatuses such as ink jet printers and printers. Gloss imparting technology has become widespread, for example, UV coating is applied to printed paper, and glossiness, image clarity, and gloss unevenness of the surface of printed matter have come to be regarded as important evaluation items in image quality.

For such glossiness, measurement methods have already been standardized, and many glossiness measuring instruments are commercially available.
However, in many cases, gloss unevenness is evaluated by visual inspection and visual inspection by an inspector, so that it is easy for personal subjectivity to enter and lacks quantitativeness. Need a lot.

Therefore, as an optical inspection method for uneven gloss, the appearance of the object surface is imaged with an imaging device such as a camera, and the evaluation of uneven gloss is quantified from the reflected light intensity distribution of the captured image and the size and distribution of the uneven gloss. Techniques to perform automatically have been proposed.
For example, a technique for evaluating gloss unevenness using a luminance level distribution has been proposed (see, for example, [Non-Patent Document 1]). However, this technique has a problem that it may not always correspond to the result of visual determination. In addition, although techniques for performing image analysis using Fourier transform have been proposed (see, for example, [Patent Document 1] and [Patent Document 2]), these all take into account human visual characteristics as described below. This is a situation that is not sufficient for quantitatively evaluating the uneven gloss.

As human visual characteristics, it is known that the gloss perceived by humans varies depending on the color of the sample. That is, it is known that even if the reflection characteristics on the object surface are the same and the reflection luminance is the same, if the gloss is felt strongly depending on the sample color, it may be hardly felt.
Therefore, a technique that takes such visual characteristics into consideration when evaluating gloss unevenness has been proposed (see, for example, [Patent Document 3]).

  However, in such a technique, the calculation required for the evaluation of gloss unevenness is relatively large and complicated, and a new method that makes it possible to perform the evaluation with a simpler calculation has been awaited.

  The present invention provides a relatively simple technique for uneven gloss on an object surface, which is used for image forming apparatuses such as copying machines, facsimile machines, printers, and printing machines, and other surface states of metals and resins other than image forming. Gloss unevenness evaluation apparatus for quantitative measurement and evaluation, gloss unevenness evaluation method, such image forming apparatus having such gloss unevenness evaluation apparatus, and computer-readable recording medium storing a program for executing such gloss unevenness evaluation method The purpose is to provide.

  In order to achieve the above object, the invention according to claim 1 is an imaging means capable of capturing an image including specularly reflected light of the sample to be evaluated, and the brightness of pixels included in the image captured by the imaging means. First calculation means for calculating a sensation component and a color component; second calculation means for calculating an average value of the glitter component and an average value of the color component calculated by the first calculation means; Third calculation means for calculating a predetermined value by integrating a spatial frequency characteristic of the deviation from the average value of the luminous component calculated by the second calculation means by performing a weighting process in consideration of human visual characteristics; The gloss unevenness evaluation value is calculated by weighting the predetermined value calculated by the third calculating unit with the degree of color using the average value of the color components calculated by the second calculating unit. The fourth calculation hand In uneven glossiness evaluation device with and.

  According to a second aspect of the present invention, in the gloss unevenness evaluation apparatus according to the first aspect, the imaging unit includes a light source unit for irradiating light toward the sample to be evaluated, and a sample to be evaluated that is irradiated from the light source unit. A light receiving unit for receiving the reflected light, and the light source unit and the light receiving unit include polarizing elements having polarization angles of 0 ° or more and less than 90 °.

  According to a third aspect of the invention, in the gloss unevenness evaluation apparatus according to the second aspect, the polarizing elements are in phase with each other.

  According to a fourth aspect of the present invention, in the gloss unevenness evaluation apparatus according to the second or third aspect, the incident angle of the light irradiated by the light source unit to the sample to be evaluated and the light irradiated from the light source unit and reflected by the sample to be evaluated The outgoing angle of the emitted light to the light receiving portion is 0 °.

  According to a fifth aspect of the present invention, in the gloss unevenness evaluation apparatus according to the first aspect, the imaging unit includes a light source unit for irradiating light toward the sample to be evaluated, and a sample to be evaluated that is irradiated from the light source unit. A light receiving unit for receiving the reflected light, an incident angle of the light irradiated by the light source unit to the sample to be evaluated, and the light reception of the light irradiated from the light source unit and reflected by the sample to be evaluated The emission angle to the part is 0 °.

  The invention according to claim 6 is the gloss unevenness evaluation apparatus according to any one of claims 2 to 5, wherein the light irradiated by the light source unit and incident on the sample to be evaluated is parallel light. Features.

According to a seventh aspect of the present invention, in the gloss unevenness evaluation apparatus according to any one of the first to sixth aspects, the first calculation means uses a CIE color system for the glitter component and the color component. The brightness component calculated by the first calculation means is an L ^* value of the CIE color system, and the degree used by the fourth calculation means is whiteness or c ^* value. It is characterized by being.

  According to an eighth aspect of the present invention, the first component for calculating the brightness component and the color component of the pixel included in the image captured by the imaging step capable of capturing an image including the specularly reflected light of the sample to be evaluated is calculated. A calculation step; a second calculation step of calculating an average value of the glitter component and an average value of the color component calculated by the first calculator; and the glitter sense calculated by the second calculator. A third calculation step of calculating a predetermined value by performing a weighting process in consideration of human visual characteristics on the spatial frequency characteristic of the deviation from the average value of the component, and the predetermined value calculated by the third calculating means Gloss unevenness using a fourth calculation step for calculating a gloss unevenness evaluation value obtained by weighting the value with a degree of color using the average value of the color components calculated by the second calculation means In the value method.

  A ninth aspect of the invention is an image forming apparatus having the gloss unevenness evaluation apparatus according to any one of claims 1 to 7 or using the gloss unevenness evaluation method according to claim 8.

  A tenth aspect of the present invention resides in a computer-readable recording medium storing a program for executing the gloss unevenness evaluation method according to the eighth aspect.

  The present invention provides a first imaging unit capable of capturing an image including specularly reflected light of a sample to be evaluated, and a first brightness component and a color component of a pixel included in the image captured by the imaging unit. Calculating means, a second calculating means for calculating an average value of the glitter component and an average value of the color component calculated by the first calculating means, and the glitter calculated by the second calculating means. Third calculation means for calculating a predetermined value by performing a weighting process in consideration of human visual characteristics on the spatial frequency characteristic of the deviation from the average value of the sensation component, and calculating the predetermined value by the third calculation means 4th calculating means for calculating a gloss unevenness evaluation value obtained by weighting the predetermined value with the degree of color using the average value of the color components calculated by the second calculating means. In the evaluation device Provided is a gloss unevenness evaluation apparatus capable of accurately and quickly performing glossy unevenness on a surface of a sample to be evaluated by quantitatively measuring and evaluating the surface using a relatively simple method regardless of the color of the sample to be evaluated. be able to.

  The imaging means includes a light source unit for irradiating light toward the sample to be evaluated, and a light receiving unit for receiving light irradiated from the light source unit and reflected by the sample to be evaluated. Assuming that the light receiving part has a polarizing element having a polarization angle of 0 ° or more and less than 90 °, it is possible to quantitatively measure and evaluate gloss unevenness on the surface of the sample to be evaluated by a relatively simple method. Can be performed by suppressing the internal reflection scattered light of the sample to be evaluated and improving the detection accuracy of the surface reflection component, and can be performed more accurately and quickly regardless of the color of the sample to be evaluated. Can be provided.

  If the polarizing elements are in phase with each other, the gloss unevenness on the surface of the sample to be evaluated is quantitatively measured and evaluated by a relatively simple method. Further, it is possible to provide a gloss unevenness evaluation apparatus that can be further suppressed and further improved in the accuracy of detecting the surface reflection component, and can be performed more accurately and promptly regardless of the color of the sample to be evaluated.

  If the incident angle of the light irradiated by the light source unit to the sample to be evaluated and the emission angle of the light irradiated from the light source unit and reflected by the sample to be evaluated to the light receiving unit are 0 ° This means that the gloss unevenness on the surface of the sample to be evaluated is quantitatively measured and evaluated by a relatively simple method, and the light from the light source unit irradiated to the sample to be evaluated is made uniform, and the color of the sample to be evaluated Accordingly, it is possible to provide a gloss unevenness evaluation apparatus that can be performed more accurately and promptly and can be advantageous for downsizing.

  If the light irradiated by the light source unit and incident on the sample to be evaluated is parallel light, the gloss unevenness on the surface of the sample to be evaluated is quantitatively measured and evaluated by a relatively simple method. Therefore, it is possible to provide a gloss unevenness evaluation apparatus that can be performed more accurately and promptly regardless of the color of the sample to be evaluated.

The first calculating means calculates the glitter component and the color component using a CIE color system, and the glitter component calculated by the first calculator is an L of the CIE color system. ^* Value, and if the degree used by the fourth calculation means is whiteness or c ^* value, the gloss unevenness of the sample surface to be evaluated is quantitatively measured and evaluated by a relatively simple method. By performing this in response to human perception of gloss unevenness, it is possible to provide a gloss unevenness evaluation device that can be performed with high accuracy and speed, regardless of the color of the sample to be evaluated.

  The present invention includes a first calculation step for calculating a brightness component and a color component of a pixel included in the image captured by the imaging step capable of capturing an image including specularly reflected light of the sample to be evaluated; A second calculation step of calculating an average value of the glitter component and an average value of the color component calculated by the first calculator; and an average value of the glitter component calculated by the second calculator A third calculation step of calculating a predetermined value by performing a weighting process in consideration of human visual characteristics to the spatial frequency characteristic of the deviation from the predetermined value calculated by a third calculation means, And a fourth calculation step of calculating a gloss unevenness evaluation value obtained by performing weighting processing with a degree of color using the average value of the color components calculated by the second calculation means. Therefore, it is possible to provide a gloss unevenness evaluation method capable of accurately and promptly measuring and evaluating gloss unevenness on the surface of the sample to be evaluated quantitatively by a relatively simple method regardless of the color of the sample to be evaluated. can do.

  Since the present invention has such a gloss unevenness evaluation apparatus or is in an image forming apparatus using such a gloss unevenness evaluation method, gloss unevenness on the surface of the sample to be evaluated is quantitatively measured and evaluated by a relatively simple method. This can be done with high accuracy and speed regardless of the color of the sample to be evaluated. For example, if the gloss unevenness exceeds the allowable range, the deterioration of the fixing device is displayed to the user or service person. It is possible to provide an image forming apparatus that can be configured to notify the user.

  Since the present invention resides in a computer-readable recording medium storing a program for executing such a gloss unevenness evaluation method, even if an existing system is used, the gloss unevenness of the surface of the sample to be evaluated can be obtained with a relatively simple method. It is possible to provide a recording medium capable of providing a program for executing a gloss unevenness evaluation method capable of performing quantitative measurement and evaluation independently of the color of the sample to be evaluated with high accuracy and speed.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic view of a gloss unevenness evaluation apparatus to which the present invention is applied, which is provided in the image forming apparatus shown in FIG. 1 or can be used alone. FIG. 7 is a schematic diagram of another configuration of the gloss unevenness evaluation apparatus to which the present invention is applied, which is provided in the image forming apparatus shown in FIG. 1 or can be used as a single unit. FIG. 4 is a principle diagram showing an operation of a polarizing element provided in the gloss unevenness evaluation apparatus shown in FIG. 2 or FIG. 3. It is the figure which showed the subjective evaluation experiment result of the scale sample used in order to evaluate gloss unevenness in the gloss unevenness evaluation apparatus shown in FIG. FIG. 4 is a block diagram of the gloss unevenness evaluation apparatus shown in FIG. 2 or FIG. 3. FIG. 4 is a correlation diagram showing a correlation between a gloss unevenness evaluation value and a subjective evaluation point in the gloss unevenness evaluation apparatus shown in FIG. 3. FIG. 4 is a schematic diagram illustrating an example of displaying and notifying the fact in the image forming apparatus illustrated in FIG. 1 when it is determined by the gloss unevenness evaluation apparatus illustrated in FIG. 3 that the gloss unevenness exceeds an allowable range. It is the correlation figure which showed the correlation with the gloss unevenness evaluation value and the subjective evaluation score in the conventional gloss unevenness evaluation apparatus.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a multifunction device of a printer and a facsimile machine, and can perform four-color full-color image formation. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside, as will be described later, when used as a printer or a facsimile.

  The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is.

  The image forming apparatus 100 includes a sheet feeding device 90 as a sheet feeding cassette as a sheet feeding device as a sheet feeding table positioned at the bottom of a transfer sheet as a recording medium as a recording medium, and a sheet feeding device. And a main body 91 on which transfer paper is supplied by the sheet feeding device 90.

  The main body 91 includes a photosensitive drum 20 as a photosensitive drum, which is a photosensitive member as an image bearing member capable of carrying an image as a toner image corresponding to each color separated into yellow, magenta, cyan, and black. A charging device 30 serving as a charging unit as a charging unit disposed around the photosensitive drum 20 along a rotation direction R1 that is counterclockwise in the figure, and above the photosensitive drum 20. An optical scanning device 40 as an exposure device as an optical writing unit as an optical writing device as a writing means, a developing device 10 as a developing unit as a developing means, and an intermediate transfer as an intermediate transfer member as an image carrier. It has a drum 50 and a cleaning device 60 as a cleaning means.

  The main body 91 also irradiates and irradiates light around the intermediate transfer drum 50 toward the intermediate transfer drum 50 along the rotation direction R2 which is the clockwise direction in the drawing, in addition to the photosensitive drum 20. An optical sensor 61 that detects the reflected light of the light from the intermediate transfer drum 50, a secondary transfer device 51 that transfers the toner image on the intermediate transfer drum 50 to the transfer paper, and the toner image after the toner image is transferred to the transfer paper And an intermediate transfer member cleaning device 52 as an intermediate transfer member cleaning means for cleaning the intermediate transfer drum 50.

  The main body 91 also has a sheet feeding device 90 at a predetermined timing that matches the timing at which the toner image on the intermediate transfer drum 50 reaches the position facing the secondary transfer device 51 by the rotation of the intermediate transfer drum 50 in the R2 direction. A registration roller pair 54 as a conveyance member that is a conveyance unit that feeds the transfer paper conveyed from the intermediate transfer drum 50 toward the secondary transfer unit 53 between the intermediate transfer drum 50 and the secondary transfer device 51, and a registration roller pair 54. And a guide plate 55 for guiding the transfer paper fed out by the second transfer unit 53.

  The main body 91 also transports the transfer paper on which the toner image on the intermediate transfer drum 50 is transferred in the secondary transfer unit 53, and the transfer paper transported by the transport means 56 enters and enters the transfer paper. Fixing device 57 as a fixing unit for fixing a toner image, gloss unevenness evaluation device 70 as gloss unevenness evaluation means for evaluating the gloss unevenness of a fixed transfer paper, and transfer paper that has passed through gloss unevenness evaluation device 70 Are discharged to the outside of the main body 91, and a discharge tray 59 as a stack portion on which the transfer paper discharged by the discharge roller 58 is stacked.

  The main body 91 is also provided in a control unit 80 as a control unit that controls the operation of the entire image forming apparatus 100 shown in FIG. 2 and an operation panel (not shown) that performs various operations of the image forming apparatus 100 shown in FIG. A display device 92 that is a liquid crystal display device serving as a display unit that also serves as a touch panel and displays various types of information regarding the image forming apparatus 100 is provided.

  The main body 91 also includes a photosensitive member driving means (not shown) that rotates the photosensitive drum 20 in the R1 direction, an intermediate transfer member driving means (not shown) that rotates the intermediate transfer drum 50 in the R2 direction, and a photosensitive drum 20 on the photosensitive drum 20. There is a primary transfer bias application power source as transfer bias application means (not shown) for applying a transfer bias for performing primary transfer by transferring the toner image to the intermediate transfer drum 50.

The charging device 30 includes a voltage applying unit (not shown) that uniformly charges the surface of the photosensitive drum 20 to a predetermined potential with a predetermined polarity in a charging region facing the photosensitive drum 20.
In this embodiment, the charging device 30 employs a non-contact type charging system, but the charging system may use a proximity roller or a contact roller.

  The exposure device 40 scans and exposes a surface to be scanned formed by the surface of the photosensitive drum 20 to form an electrostatic latent image, and a laser diode 41 as a light source that emits laser light based on an image signal. A polygon mirror 42 as a polygon mirror that scans the laser light emitted by the laser diode 41 by its rotation, a polygon motor 43 that is a high-speed motor as a driving means for rotating the polygon mirror 42 at high speed, and a polygon mirror An f-θ lens 44 that forms an image of the laser beam scanned by the image 43 on the photosensitive drum 20 and a reflection mirror 45 that reflects the laser beam transmitted through the f-θ lens 44 and scans the photosensitive drum 20. Have. The light emission intensity of the laser diode 41, that is, the exposure intensity, in other words, the exposure amount can be adjusted by the control of the control unit 80.

  The cleaning device 60 intermediateizes the toner remaining on the photosensitive drum 20 after the toner image is transferred to the intermediate transfer drum 50 as the photosensitive drum 20 rotates in the R1 direction, that is, the primary transfer residual toner. A fur brush, a web, and the like (not shown) that are removed from the transfer drum 50 are provided.

  The intermediate transfer drum 50 is configured by providing an elastic layer on the outer peripheral surface of a cylindrical substrate, is in contact with the surface of the photosensitive drum 20, and is a primary transfer portion between the photosensitive drum 20 and the intermediate transfer drum 50. A transfer nip 59 is formed.

  The secondary transfer device 51 applies a secondary transfer bias application power source as a transfer bias application unit (not shown) that applies a transfer bias for performing the secondary transfer by transferring the toner image on the intermediate transfer drum 50 onto a transfer sheet. Have.

  The intermediate transfer member cleaning device 52 removes the toner remaining on the intermediate transfer drum 50 after the toner image is transferred onto the transfer paper as the intermediate transfer drum 50 rotates in the R2 direction, that is, the secondary transfer residual toner. A fur brush, a web, and the like (not shown) that are removed from the intermediate transfer drum 50 are provided.

  The fixing device 57 includes a fixing roller 57a having a heat source therein, and a pressure roller 57b that is in pressure contact with the fixing roller 57a and forms a fixing nip as a fixing portion that is a pressure contact portion between the fixing roller 57a. Yes. The fixing device 57 fixes the toner image carried on the surface of the transfer paper by the action of heat and pressure by passing the transfer paper carrying the toner image through the fixing nip.

  Although not shown, the optical sensor 61 is reflected by the intermediate transfer drum among the light emitting unit as a light source that irradiates infrared light toward the intermediate transfer drum 50 and the infrared light emitted from the light emitting unit. It has a light receiving portion that detects reflected light that is scattered light, and a holder that holds them. The light receiving unit inputs a signal having an output voltage corresponding to the detected intensity of the reflected light to the control unit 80.

  The developing device 10 develops and visualizes the electrostatic latent image formed by the exposure device 40. The electrostatic latent image is stored in yellow (Y), cyan (C), magenta (M), and black. Development units 10Y, 10C, 10M, and 10BK, which are respectively developed with toners of the respective colors (BK) and carry the respective color toner images of yellow, cyan, magenta, and black on the photosensitive drum 20, respectively, and a rotary incorporating these 11, a rotary drive unit (not shown) that rotates the rotary 11 in the R3 direction to selectively position one of the developing units 10Y, 10C, 10M, and 10BK to face the photosensitive drum 20, and a developing unit 10Y. The figure which applies the developing bias for adjusting the toner amount of each color which transfers to the photosensitive drum 20 from 10C, 10M, 10BK There and a developing bias applying means. The developing device 10 is a revolver-type developing device in that development is performed with one of the developing devices 10Y, 10C, 10M, and 10BK selectively opposed to the photosensitive drum 20.

  As shown in FIG. 2, the gloss unevenness evaluation device 70 can capture an image including specularly reflected light of the sample SA to be evaluated, which is a transfer sheet that has passed through the fixing device 57 in this embodiment, which is a target for inspection of gloss unevenness. An imaging device 71 as an imaging means, and a flat plate-like placement plate 72 as a placement portion on which the sample SA to be evaluated that is placed opposite to the imaging device 71 and is imaged by the imaging device 71 is placed. Yes.

  The imaging device 71 has a light source unit 73 as a light emitting unit for irradiating light toward the sample SA to be evaluated mounted on the mounting plate 72, and is reflected from the sample SA to be irradiated from the light source unit 73. A light receiving unit 74 that receives light, that is, reflected light, and images the sample SA to be evaluated, and a gloss that performs processing related to gloss unevenness evaluation for an image of the sample SA to be evaluated that is realized as a function of the control unit 80 The light source unit 73 and the light receiving unit are configured so that the incident angle of the light from the light emitting unit 73 and the reflection angle that is the incident angle of the reflected light to the light receiving unit 74 are both θ with respect to the surface of the unevenness evaluation processing unit SA. There is an incident / reflection angle adjusting means (not shown) for adjusting the position of the portion 74.

  The light source unit 73 transmits a light source 73a that is an illumination light source that emits light toward the sample SA to be evaluated, a pinhole 73b that transmits part of the light emitted by the light source 73a, and light that has passed through the pinhole 73b. A lens 73c that collimates the light emitted from the light source 73a together with the pinhole 73b, a polarizing filter 73d as a polarizing element that transmits light passing through the lens 73c, and a holder 73e that holds these lenses. .

  The light receiving unit 74 includes a polarizing filter 74a serving as a polarizing element through which reflected light is transmitted, a CMOS camera 74b serving as a light receiving camera that receives the reflected light transmitted through the polarizing filter 74a and captures an image of the sample SA to be evaluated, and the like. And a holder 74c that holds The CMOS camera 74b converts the received light into an image signal for each pixel and inputs it to the control unit 80 as a gloss unevenness evaluation processing unit.

  The incident / reflection angle adjusting means includes a support member that supports the holder 73e and the holder 74c, and a gear mechanism that rotates the support members in synchronization with each other, and the surface of the sample SA to be evaluated is driven by the gear mechanism. The positions of the light source unit 73 and the light receiving unit 74 are adjusted in synchronization so that the incident angle of light from the light emitting unit 73 and the reflection angle of reflected light to the light receiving unit 74 are both θ. Accordingly, it is possible to perform highly accurate gloss unevenness evaluation by setting each angle θ to the same angle as the observation angle of the sample to be evaluated in the subjective evaluation experiment described later.

  The imaging device 71 may be configured as shown in FIG. In addition, about the structure similar to the structure shown in FIG. 2 and shown in FIG. 2, the code | symbol same as the code | symbol shown in FIG. 2 is attached | subjected, and description is abbreviate | omitted suitably.

  The imaging device 71 shown in FIG. 3 includes a half mirror 75 that reflects the light emitted from the light source unit 73 toward the sample SA to be evaluated and transmits the light reflected by the sample SA to be evaluated and transmitted to the light receiving unit 74. Yes. The light source unit 73 includes a diffusion plate 73f that transmits light emitted from the light source 73a and a light control film 73g that transmits light that has passed through the diffusion plate 73f.

  In the imaging apparatus 71 shown in the figure, the internal configuration of the light source unit 73 may be the same as the internal configuration of the light source unit 73 shown in FIG. 2, or the internal configuration of the light source unit 73 shown in FIG. 3 may be the same as the internal configuration of the light source unit 73 shown in FIG. 3, or an appropriate combination of the internal configuration of the light source unit 73 shown in FIG. 2 and the internal configuration of the light source unit 73 shown in FIG. The internal configuration of the unit 73 may be used. However, the light incident on the sample SA to be evaluated is preferably collimated from the viewpoint of improving the accuracy of detecting uneven gloss.

  The imaging device 71 shown in FIG. 3 has an incident angle of the light emitted from the light source unit 73 to the sample SA to be evaluated and the reflection of the light emitted from the light source unit 73 and reflected by the sample SA to be evaluated to the light receiving unit 74. Both angles are 0 °. Thereby, the uniform illumination with respect to the sample SA to be evaluated is possible.

  In both the imaging device 71 shown in FIG. 2 and the imaging device 71 shown in FIG. 3, the polarizing filter 73d and the polarizing filter 74a are in phase with each other. Thereby, as will be described below, half of the internal diffuse reflection component contained in the reflected light from the sample SA to be evaluated is blocked, and the detection accuracy of optical unevenness is improved.

  The light reflected by the surface of the incident light has a polarizing property, but the internally diffuse reflected light emitted after entering the toner and repeatedly scattering and absorbing by the colorant and the transfer paper has no polarizing property. The polarizing filter 73d and the polarizing filter 74a can suppress internal diffuse reflection light by incorporating them in parallel using this polarization characteristic.

FIG. 4 is a diagram showing the principle of separating the surface reflection component and the internal diffuse reflection light using the polarization filter 73d and the polarization filter 74a. The polarizing filter 73d and the polarizing filter 74a transmit the S-polarized component. Uppercase letters S and D represent surface reflection and internal reflection, respectively, and lowercase letters p and s represent a P-polarized component and an S-polarized component, respectively. At this time, since the internal diffuse reflection light loses its polarization property, this value is expressed as Dsp. Further, the S-polarized component of the internally diffuse reflected light reflected from the sample SA to be evaluated, which is an object, is represented as I (Ds), and the S-polarized component of the surface reflected light is represented as I (Ss). S-polarized light components transmitted through 74a are defined as I (Dss) and I (Sss).
Then
I (Sss) = I (Ss), I (Dss) = I (Ds) = Dsp / 2
Assuming that the component imaged by the CMOS camera 74b is Iss, Iss is the sum of I (Sss) and I (Dss).

  Therefore, half of the internally diffuse reflected light Dsp is blocked by the light received by the CMOS camera 74b, thereby improving the detection accuracy of the surface reflection component and improving the gloss unevenness evaluation accuracy. That is, for example, when there is a sample having a low glossiness but a large gloss unevenness perceived by humans, the detection sensitivity of the gloss unevenness can be lowered unless internal diffuse reflection is suppressed. However, the polarizing filter 73d and the polarizing filter 74a are provided. If used, internal diffuse reflection is suppressed, so that the accuracy of detecting uneven glossiness is improved. In particular, as described later, in this embodiment, not only R, G, B, and K having low lightness, but also samples of C, M, and Y having high lightness are used. By using the filter 73d and the polarizing filter 74a, quantitative evaluation of gloss unevenness can be performed satisfactorily.

  Note that the polarization filter 73d and the polarization filter 74a have a surface reflection component detection accuracy due to the blocking action of the internal diffuse reflection light Dsp as long as the deflection angle of the polarization filter 73d and the polarization filter 74a is not in the range of 0 ° but within a range of 0 ° to less than 90 °. And the gloss unevenness evaluation system is improved.

The control unit 80 includes a CPU as information calculation means, a memory as storage means, and the like.
The control unit 80 as the gloss unevenness evaluation processing unit is configured by the CPU to control the light emission of the light source 73a, drive the CMOS camera 74b, and reflect light from the sample SA to be evaluated received by the CMOS camera 74b. Is stored in the memory as an image signal for each pixel which is an output value of the CMOS camera 74b. In this respect, the control unit 80 as the gloss unevenness evaluation processing unit functions as a light emission control unit, an imaging control unit, and an imaging storage unit.
The controller 80 adjusts the developing bias applied by the developing bias applying means.
The control unit 80 performs communication for exchanging information with the external information input / output device, and also drives the display device 92 to display the status of the image forming apparatus 100 on the display device 92. The control unit 80 functions as a gloss unevenness evaluation processing unit when causing the display device 92 to perform a display to be described later regarding gloss unevenness.

  Although not shown in detail, the sheet feeding device 90 is configured to feed the uppermost transfer paper loaded toward the registration roller pair 54 by rotating the feeding roller and operating the separation roller. The transferred transfer paper is guided to 91 and stopped by abutting against the registration roller pair 54.

  In the image forming apparatus 100 having such a configuration, the image formation is performed by the input unit including image data for performing image formation from an external information input / output device (not shown) connected to the image forming apparatus 100 and data relating to an image formation start instruction. It is started by inputting to 80.

  Based on the input image data, the control unit 80 repeatedly forms an image on the photosensitive drum 20 for each color based on the image data of the color components included in the image data. The image data for each color component is video data having 8-bit density information.

  Specifically, video data relating to a yellow image is included in the image data. When this image is formed, the photosensitive drum 20 is driven in the R1 direction and charged by the charging device 30. Based on the optical information, the photosensitive drum 20 is irradiated with laser light from the laser diode 41 by driving the control unit 80 so as to form an electrostatic latent image corresponding to the yellow image pattern. The photosensitive drum 20 is charged with a laser beam, and an electrostatic latent image is formed.

  The control unit 80 drives the rotary 11 in the R3 direction so that the developing device 10Y occupies the developing position facing the photosensitive drum 20, and the electrostatic latent image reaches the developing position by rotating the photosensitive drum 20 in the R1 direction. The electrostatic latent image is developed as a yellow toner image by the developing device 10Y.

  The yellow toner image is primarily transferred to the intermediate transfer drum 50 when it reaches the primary transfer nip 59 by the rotation of the photosensitive drum 20 in the R1 direction. The primary transfer residual toner remaining on the photoconductive drum 20 after the primary transfer is performed is removed by the cleaning device 60, and the photoconductive drum 20 thus cleaned is re-imaged. Served for formation.

  When the image data input to the control unit 80 as described above includes video data relating to an image of another color, the image of the other color is formed as the re-image formation. In addition, as described above, a series of image forming processes, that is, charging, exposure, development, primary transfer, and cleaning steps are repeated. For example, when the image data input to the control unit 80 is full-color image data, following the formation of the yellow toner image, magenta, cyan, and black toner images are formed. Are sequentially transferred so as to overlap the same position of the intermediate transfer drum 50, so that four color toner images are carried on the intermediate transfer drum 50 in an overlapping manner.

  When the intermediate transfer drum 50 carries toner images of all the colors included in the image data input to the control unit 80, it is carried by the secondary transfer unit 53 by the operation of the secondary transfer device 51. The toner images are transferred to the transfer paper at once. The transfer paper is fed from the sheet feeding device 90 and supplied through the guide plate 55 by the registration roller pair 54 so that the toner image enters the secondary transfer unit 53 at the timing when the toner image reaches the secondary transfer unit 53. It has been done.

  The transfer paper carrying the toner image enters the fixing device 57 through the conveying means 56, and is carried by the action of heat and pressure when passing through the fixing portion between the fixing roller 57a and the pressure roller 57b. The toner image is fixed, and a color image is formed on the transfer paper. The fixed transfer paper that has passed through the fixing device 56 is evaluated for gloss unevenness as will be described later when passing through the gloss unevenness evaluation device 70, and is stacked on the paper discharge tray 59 by the discharge roller 58. On the other hand, the intermediate transfer drum 50 that has finished the secondary transfer is cleaned by removing the residual secondary transfer toner remaining on the intermediate transfer body cleaning device 52 to prepare for the next image formation.

  When such image formation is performed in the image forming apparatus 100, the density of the toner image varies depending on the environment such as temperature and humidity, and various conditions such as the number of images to be formed, that is, the number of prints, particularly when forming a color image. In this case, even a slight change in the density of each toner image can greatly change the color tone as a color image, and the original desired color tone may not be obtained.

  Therefore, in order to determine the density of the toner image, the image forming apparatus 100 forms a patch which is a toner image for detecting each color density under the same conditions regarding the above-described image forming process, and the density of the patch is optically determined. By detecting with the type sensor 61 and feeding back the detection result, the condition relating to the image forming process, for example, the exposure amount, the developing bias, and the like are adjusted, and control for making the color tone constant is performed.

  Further, when such image formation is performed in the image forming apparatus 100, the fixing device 57 deteriorates depending on the environment such as temperature and humidity, and various conditions such as the number of image formations, that is, the number of prints, especially when forming a color image. As a result, the glossiness can be greatly changed, and uneven glossiness can occur, making it impossible to obtain the original desired printed matter.

  Therefore, in the image forming apparatus 100, the gloss unevenness evaluation device 70 evaluates the gloss unevenness of the transfer paper that has passed through the fixing device 57. Further, if the evaluated gloss unevenness exceeds the allowable range, As shown in FIG. 8, the display device 92 is driven to display on the display device 92 that the gloss unevenness exceeds the allowable range and that the fixing device 57 should be replaced.

Evaluation of gloss unevenness requires an evaluation standard.
Therefore, first, a subjective evaluation experiment performed in producing such a reference will be described, and then a gloss unevenness evaluation value calculation method derived based on the result obtained from this experiment will be described.

(Subjective evaluation experiment)
In the subjective evaluation experiment, the subject is presented with one sample to be evaluated at a time, and the score is given in advance to the position of the scale sample in which the gloss unevenness is stepped in advance. This is a technique called a stage evaluation method.

  In order to perform the stage evaluation method, a solid image sample as a sample to be evaluated as a reference for evaluating the sample SA to be evaluated by an electrophotographic output device such as the image forming apparatus 100, and a reference for evaluating the solid image sample A scale sample was created.

  In creating a solid image sample, C and M were used in order to measure psychological gloss unevenness due to color differences, changing the paper type, output model, fixing temperature, etc., and changing the degree of gloss unevenness and glossiness. , Y, R, G, B, K 7 solid images, a total of 35 samples were created. The image size was 30 × 30 mm, and it was attached to an 80 × 50 mm white mount for easy handling.

  As scale samples, seven types of samples with different glossiness and glossiness were prepared using K toner. The sample size was 30 × 30 mm. The glossiness of the prepared scale sample is as shown in the following table. The glossiness was measured at an angle corresponding to the angle θ described above of 60 °.

  The scale samples arranged in stages need to have an equal interval of the subjective evaluation score between adjacent scale samples. Then, in order to confirm whether the subjective score distance between the scale samples is equal, a subjective evaluation experiment was performed using Scheffe's paired comparison method.

Here, the pair comparison method will be described.
A pair of scale samples A and B presented to the subject are compared. When the gloss unevenness of the scale sample B is A >> B with respect to the scale sample A, when +2 point A> B, and when +1 point A = B, 0 When point A <B, -1 point A << B When -2 points, the scale samples are scored.

  The test subject was evaluated from a position 350 mm away under an observation environment set to directly see the specularly reflected light on the surface of the scale sample. The test was conducted on a total of 25 subjects, image evaluation engineers and fixing engineers. The evaluation score for each scale sample was calculated by applying the quantification type III analysis method to the result of the evaluation experiment.

  The results are shown in FIG. The horizontal axis shows the scale samples in the order of subjective evaluation points, and the vertical axis shows the subjective evaluation points. The smaller the value, the smaller the gloss unevenness. Looking at the subjective evaluation points of the scale samples, it was confirmed that the adjacent evaluation points were equally spaced, and there was no problem using these scale samples as scale samples.

Therefore, a stage evaluation experiment is performed using such a scale sample.
The scale sample is pasted on the mount with a numerical value (score) of 1 to 7 written so that the unevenness is arranged in order. The larger the numerical value, the smaller the unevenness becomes.

  A total of 35 solid image samples of C, M, Y, R, G, B, and K7 colors are presented one by one at random, and the numerical value of the scale sample that feels uneven glossiness is selected. The score is given in increments of 0.5. The solid image sample whose score was out of the scale range was finally excluded from the verification sample because the score distance to the scale sample was not accurately determined.

  After conducting the above experiment, the average value of the points assigned to each solid image sample is converted to the scale of the paired comparison evaluation experiment result calculated in advance using quantification type III, and the final subjective evaluation score And

(Calculation of gloss unevenness evaluation value)
A method for calculating the evaluation value of psychological unevenness quantified by the subjective evaluation experiment will be described with reference to FIG. 6 as appropriate. In FIG. 6, arrows indicate the direction in which signals, data, and the like flow.

  In this embodiment, the gloss unevenness evaluation value calculation method uses a reference sample having a uniform gloss for correcting illuminance unevenness and an evaluation sample corresponding to the sample SA to be evaluated, and includes a specularly reflected light to be evaluated. An image is obtained by imaging, and a gloss unevenness evaluation value is calculated using a value obtained by weighting the variation of the brightness component of the image in consideration of human visual characteristics and a color component, and evaluating the gloss unevenness. Including doing.

  These samples were imaged using the imaging device 71 which is the imaging means shown in FIG. 3 (FIG. 6 (S1): imaging step). A black polyester film having a 60 ° specular gloss of 103.8% was used as the reference sample. As the CMOS camera 74b, a three-layer CMOS camera (model number: CSF5M7C3L18NR) manufactured by Toshiba TELI having a reading resolution of 2092.7 dpi was used. However, the type and resolution of the CMOS camera 74b are not limited to this. For the light source 73a, a CCS coaxial illumination device (model number: LFV2-50a-SW2) was used as a white LED which is an LED light source. Both the light control film 73f and the polarizing filter 73g were manufactured by Edmund Optics Japan.

  For the evaluation value calculation, the center portion of the photographed image is trimmed to 512 × 512 pixels (trimming step). Although this time is calculated with 512 × 512 pixels, the size used for the calculation is not limited to this. The control unit 80 as the gloss unevenness evaluation processing unit stores and holds at least the first image of the trimmed reference sample and the second image of the evaluation sample. Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as an image storage unit that performs an image storage step (FIG. 6 (S2)).

  The color image signals of the reference sample imaged under these conditions are Rref (x, y), Gref (x, y), and Bref (x, y). Similarly, the color image signals of the evaluation samples are Rs (x, y), Gs (x, y), and Bs (x, y).

  Next, as shown in the following equation, the second image of the evaluation sample is divided by the first image of the reference sample and normalized. The normalized results are R (x, y), G (x, y), and B (x, y). Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as a dividing unit that calculates a third image in which a light source variation with time and illuminance unevenness in the image are corrected by performing a division step (see FIG. 6 (S3)). K in the equation is a proportionality constant and has a meaning of preventing a digit loss after the calculation, and is not essential in the present invention. In this experiment, k = 100.

R (x, y) = k × Rs (x, y) / Rref (x, y)
G (x, y) = k × Gs (x, y) / Gref (x, y) (Expression 2)
B (x, y) = k × Bs (x, y) / Bref (x, y)

  From the image data R (x, y), G (x, y), and B (x, y) normalized by (Expression 2), as shown in the following expression, tristimulus values (X, Y, Z).

In (Expression 3), the sRGB space is used to convert the color image signal into the tristimulus values. This is because the conversion matrix is known, and other spaces may be used.
A conversion formula for converting a color image signal into a tristimulus value in an arbitrary color space (for example, a tristimulus value on an arbitrary monitor) is, for example, a chromaticity point or tristimulus value of a phosphor of the monitor, and If the white point or tristimulus value of the monitor is known, a conversion matrix can be obtained. This conversion matrix derivation method is a known technique and is not limited.

X, Y, and Z calculated in (Expression 3) are converted into CIELAB color values (L ^* , a ^* , b ^* ). Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as an L ^* a ^* b ^* conversion unit in the CIE that performs the L ^* a ^* b ^* conversion step in the CIE color system as the CIELAB color specification value ( FIG. 6 (S4).

In this way, the control unit 80 as the gloss unevenness evaluation processing unit includes the glitter component L ^* and the color components a ^* and b ^* that are included in the captured image of the evaluation sample imaged by the imaging device 71. It functions as a first calculation means for performing a first calculation step for calculating.

The conversion from the tristimulus values X, Y, Z to the CIELAB color values L ^* , a ^* , b ^* is already a well-known method and is omitted here. The color image data represented by the CIELAB color values L ^* , a ^* , b ^* is L ^* (x, y), a ^* (x, y), b ^* (x, y).
The CIELAB color specification value is calculated from the tristimulus values X, Y, and Z, but other color spaces can be used as long as they can be converted into a brightness component that is a glitter component and a chromaticity component that is a color component. May be. For example, a CIELch uniform color space may be used.

Average values L ^* ave, a ^* ave, L ^* (x, y), a ^* (x, y), b ^* (x, y) represented by CIELAB color values L ^* , a ^* , b ^* b ^* ave is calculated, a deviation from the average value L ^* ave for each pixel of the lightness component L ^* (x, y) is calculated, and a deviation image hL (x, y) is output.
hL (x, y) = (L ^* (x, y) −L ^* ave) (Expression 4)

Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as an average value calculating unit that performs an average value calculating step of calculating the average values L ^* ave, a ^* ave, and b ^* ave (FIG. 6 (S5)). ).

  In this manner, the control unit 80 as the gloss unevenness evaluation processing unit calculates the average value of the glitter component and the average value of the color component calculated by the control unit 80 as the first calculation unit. It functions as second calculation means for performing the calculation step.

Further, the control unit 80 as the gloss unevenness evaluation processing unit functions as a deviation image calculation unit that performs a deviation image calculation step of calculating a deviation image by subtracting the average value L ^* ave from the L ^* component (S6 in FIG. 6). )).

  A two-dimensional Fourier transform is performed on the lightness deviation image hL (x, y) obtained by (Expression 4) to obtain a two-dimensional Wiener spectrum. At this time, a two-dimensional winner spectrum is displayed in polar coordinates. The Wiener spectrum displayed in polar coordinates is defined as hL ′ (λ, θ) (λ is the spatial frequency (c / deg), and θ indicates the image direction). The winner spectrum hL ′ (λ, θ) is integrated in the range of 0 to 2π to be one-dimensional. Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as a spatial frequency characteristic calculating unit that performs a spatial frequency characteristic calculating step of calculating a spatial frequency characteristic by Fourier transform on the deviation image (FIG. 6 (S7)). ).

Next, the one-dimensional winner spectrum hL ′ (λ) is multiplied by the human visual spatial frequency characteristic VTF (λ) (Visual Transfer Function) (see, for example, Equation (5)) shown in FIG. Then, as shown in (Equation 6), the calculation result is HL ^* . Here, the control unit 80 as the gloss unevenness evaluation processing unit functions as a visual characteristic multiplication unit that performs a visual characteristic multiplication step of calculating a spatial frequency distribution by multiplying the spatial frequency characteristic by the spatial frequency characteristic of human vision ( Together with FIG. 6 (S8)), it functions as an integral calculating means for performing an integral calculating step for performing integration in a predetermined section with respect to such a spatial frequency distribution (FIG. 6 (S9)).

In this way, the control unit 80 as the gloss unevenness evaluation processing unit changes the human visual characteristic to the spatial frequency characteristic of the deviation from the average value of the glitter component calculated by the control unit 80 as the second calculation unit. It functions as a third calculation means for performing a third calculation step of calculating an integral value HL ^* which is a predetermined value by performing a weighting process in consideration of the above.

Some VTF (λ) have already been reported, for example
VTF (λ) = 5.05 · exp (−0.138 · λ) · (1-exp (−0.1 · λ)) (Expression 5)
There is a report that it is expressed. However, the present invention is not limited to VTF (λ) in (Formula 5), and other VTF (λ) may be used.

  Further, the hunter whiteness W is calculated by the following equation as a correction term for correcting the influence of the appearance of unevenness due to the degree of color.

Using the HL ^* calculated by (Expression 6) and the Hunter whiteness W that is the color component calculated by (Expression 7), a gloss unevenness evaluation value model represented by the following expression is created. Here, the control unit 80 as the gloss unevenness evaluation processing unit evaluates the gloss unevenness as the gloss unevenness evaluation amount using the integrated value HL ^* and the average value of the color components calculated by the control unit 80 as the average value calculating means. It functions as gloss unevenness evaluation value calculating means for performing a gloss unevenness evaluation value calculating step for calculating a value (FIG. 6 (S10)).
Gloss unevenness evaluation value = p1 · (100−W) ^p2 · HL ^* + p3 (8 formulas)

In this way, the control unit 80 as the gloss unevenness evaluation processing unit calculates the integral value HL ^* calculated by the control unit 80 as the third calculation unit by the control unit 80 as the second calculation unit. It functions as a fourth calculation means for performing a fourth calculation step of calculating a gloss unevenness evaluation value that has been weighted with the degree of color using the average value of the color components.

In (Equation 8), p1 to p3 are coefficients. When HL ^* and W are explanatory variables, the gloss unevenness subjective evaluation value of each sample which is priced by subjective evaluation is set as an objective variable, a model shown in (Equation 8) is established, and p1 to p3 are obtained by the least square method. The coefficient values are p1 = 1.21179, p2 = 0.44816, and p3 = −1.5000157. As shown in FIG. 7, the contribution rate is 0.94, which indicates that gloss unevenness can be quantitatively evaluated with very high accuracy. It was done.

As weighting according to the degree of color, hunter whiteness may not be used as a color component, but saturation may be used as a color component. When using saturation, in the L ^* , a ^* , b ^* color system, the saturation c ^* is calculated by the following equation.

In this case, using the HL ^* calculated in (Equation 6) and the saturation c ^* calculated in (Equation 9), a gloss unevenness evaluation value model represented by the following equation is created, and the coefficient is determined based on the subjective evaluation result. To do. Also in this case, the control unit 80 as the gloss unevenness evaluation processing unit uses the integrated value HL ^* and the average value of the color components calculated by the control unit 80 as the average value calculating means as the gloss unevenness evaluation amount. It functions as gloss unevenness evaluation value calculating means for performing the gloss unevenness evaluation value calculating step for calculating the evaluation value (FIG. 6 (S10)). Similarly, the control unit 80 as the gloss unevenness evaluation processing unit adds the color calculated by the control unit 80 as the second calculation unit to the integral value HL ^* calculated by the control unit 80 as the third calculation unit. It functions as a fourth calculation means for performing a fourth calculation step of calculating a gloss unevenness evaluation value obtained by performing weighting processing with a degree of color using an average value of components.
Gloss unevenness evaluation value = p1 · c ^{* p2} · HL ^* + p3 (10 formulas)

For reference comparison, FIG. 9 shows the results of measurement and analysis of samples prepared this time with uneven gloss of C, M, Y, R, G, B, and K according to the example of [Patent Document 3]. The contribution rate is 0.77. In the example of [Patent Document 3], only four colors K, R, G, and B have been verified, and it has been found that the accuracy of gloss unevenness evaluation is low for the specific sample prepared this time. . That is, according to the gloss unevenness evaluation apparatus 70 to which the present invention is applied, it has been found that the gloss unevenness evaluation accuracy is improved as compared with the conventional apparatus. In addition, the gloss unevenness evaluation apparatus 70 does not perform Fourier transform of a ^* and b ^* when calculating the Hunter whiteness W and the chroma c ^* used to calculate the gloss unevenness evaluation value. In comparison, since the calculation required for evaluating gloss unevenness is relatively small and simple, it is possible to perform evaluation in a shorter time.

  The control unit 80 serving as the gloss unevenness evaluation processing unit stores in advance a threshold value to be compared with the gloss unevenness evaluation value calculated by the control unit 80 serving as the fourth calculating unit. 6 functions as gloss unevenness occurrence determination means for performing a gloss unevenness occurrence determination step of determining whether or not gloss unevenness has occurred (FIG. 6 (S11)). Specifically, the control unit 80 as gloss unevenness occurrence determination means divides the threshold value from the gloss unevenness evaluation value, determines whether this value is a positive value, and if it is a positive value, It is determined that gloss unevenness has occurred, and when the value is 0 or less, it is determined that gloss unevenness has not occurred.

  In this way, the control unit 80 as the gloss unevenness evaluation processing unit calculates a value obtained by dividing the threshold value, that is, the gloss unevenness determination reference value, from the gloss unevenness evaluation value calculated by the control unit 80 as the fourth calculation unit. It functions as a fifth calculation means for performing the fifth calculation step.

Note that the control unit 80 as the gloss unevenness evaluation processing unit functions as gloss unevenness determination reference value storage means in that the threshold value is stored.
In addition, in the case of using the hunter whiteness W or the saturation c ^* to calculate the gloss unevenness evaluation value, when the imaging device 71 shown in FIG. Further, for example, the image is picked up by changing the angle θ by 10 ° to calculate the gloss unevenness evaluation value for each, and the average value is compared with the threshold value to be used for the final gloss unevenness evaluation. Anyway. In this way, a more accurate evaluation can be made in consideration of various illumination angle conditions.

When the control unit 80 serving as the gloss unevenness evaluation processing unit determines that the gloss unevenness has occurred by the control unit 80 serving as the gloss unevenness generation determining unit, the control unit 80 drives the display device 92 serving as the display unit. As shown, a display step is performed to display on the display device 92 that the gloss unevenness exceeds the allowable range and that the fixing device 57 should be replaced (FIG. 6 (S12)). Gloss unevenness often occurs due to deterioration of the fixing device 57, particularly the fixing roller 57a, etc., and since such deterioration does not recover naturally, once it deteriorates, an image with large gloss unevenness will continue to be output. . Therefore, when the gloss unevenness exceeds the threshold and exceeds the allowable range, the fixing device 57 has reached the end of its life, and the user or serviceman is notified that replacement should be performed. In this respect, the display device 92 functions as a display unit and a notification unit, and the above-described display step is also performed as a notification step.
In FIG. 8, the threshold value and the gloss unevenness evaluation value are displayed, but these displays are arbitrary. Further, such a threshold value may be changed by an appropriate input unit and stored in the control unit 80 as a gloss unevenness determination reference value storage unit.

  The operation, function, and execution of the gloss unevenness evaluation method of the gloss unevenness evaluation apparatus 70 as described above are realized by executing the gloss unevenness evaluation program stored in the memory. In this respect, the memory functions as gloss unevenness evaluation program storage means.

  The gloss unevenness evaluation program and the computer-readable recording medium on which the gloss unevenness evaluation program is described will be described. Such a program is stored in the memory of the control unit 80 and executed by the CPU of the control unit 80. It corresponds to a possible recording medium. However, a computer-readable recording medium storing such a program includes a semiconductor medium (for example, ROM, nonvolatile memory, etc.), an optical medium (for example, DVD, MO, MD, CD-R, etc.), a magnetic medium (for example, Any of hard disks, magnetic tapes, flexible disks, etc. may be used. In such a recording medium, a storage device such as a hard disk of a server computer in an external information input device or the like storing such a program is also downloaded and distributed through a user computer connected via a network such as the Internet or a LAN. It is included in this case. The execution mode of the program includes a case where the operating system or the like performs part or all of the actual processing based on the instruction of the loaded program, and the above-described method is realized by the processing.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the gloss unevenness evaluation apparatus may be used not only in a state where it is incorporated in the image forming apparatus, but also as an independent apparatus used alone. In this case, for example, the surface of metal, resin, etc. It is used as an apparatus for quantitatively measuring and evaluating uneven gloss on the surface of an object, used for state analysis and the like. In consideration of such points, the gloss unevenness evaluation program can perform at least steps S4 to S10 or at least the first calculation step to the fourth calculation step among the above-described steps. good.

  When the gloss unevenness evaluation apparatus is incorporated in an image forming apparatus, the image forming apparatus forms a toner image of each color sequentially on a single photosensitive drum as in the above-described revolver type image forming apparatus, and converts each color toner image. A so-called one-drum system that obtains a color image by superimposing sequentially may be used, but a so-called tandem-type image forming apparatus may be used, or only a mono-color image may be formed.

  In any type of image forming apparatus, the toner image of each color may be directly transferred onto a sheet such as the transfer sheet S without using an intermediate transfer member. In this case, the toner images on the plurality of image carriers are directly transferred to the sheet in a process in which the sheet is conveyed by, for example, a conveyance belt as a sheet conveyance body.

The image forming apparatus may be a copying machine, a printer, a facsimile machine, or a plotter as a single unit instead of a printer / facsimile multifunction machine, or a combination machine such as a copying machine / printer multifunction machine. There may be.
In addition, the image forming apparatus may be an ink jet printer that forms an image using ink instead of toner, or may be a printing machine such as a stencil printing apparatus or an offset printing apparatus.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 70 Gloss unevenness evaluation apparatus 71 Imaging means 73 Light source part 73d Polarization element 74 Light receiving part 74a Polarization element 80 1st-4th calculation means 100 Image forming apparatus S4 1st calculation step S5 2nd calculation step S6-S9 3rd Calculation step S10 Fourth calculation step SA Sample to be evaluated θ Incident angle, outgoing angle

Japanese Patent Laid-Open No. 08-297092 Japanese Patent Application Laid-Open No. 10-096669 JP 2002-350355 A

H. Fujiwara et. al. 1990 TAPPI Coat. Conf. Proc. , 209 (1990)

Claims (10)

Imaging means capable of imaging an image including specularly reflected light of the sample to be evaluated;
First calculation means for calculating the brightness component and the color component of the pixels included in the image picked up by the image pickup means;
Second calculation means for calculating an average value of the glitter components and an average value of the color components calculated by the first calculation means;
Third calculation means for calculating a predetermined value by integrating a spatial frequency characteristic of the deviation from the average value of the luminous component calculated by the second calculation means by performing a weighting process in consideration of human visual characteristics; ,
A gloss unevenness evaluation value is calculated by performing a weighting process on the predetermined value calculated by the third calculation unit with the degree of color using the average value of the color components calculated by the second calculation unit. A gloss unevenness evaluation apparatus having fourth calculation means. The gloss unevenness evaluation apparatus according to claim 1,
The imaging means includes a light source unit for irradiating light toward the sample to be evaluated, and a light receiving unit for receiving light irradiated from the light source unit and reflected by the sample to be evaluated.
The gloss unevenness evaluation apparatus, wherein the light source unit and the light receiving unit have polarizing elements having polarization angles of 0 ° or more and less than 90 °. The gloss unevenness evaluation apparatus according to claim 2,
The gloss unevenness evaluation apparatus, wherein the polarizing elements are in phase with each other. In the gloss unevenness evaluation apparatus according to claim 2 or 3,
The incident angle of the light irradiated by the light source unit to the sample to be evaluated and the emission angle of the light irradiated from the light source unit and reflected by the sample to be evaluated are 0 °. Gloss unevenness evaluation device. The gloss unevenness evaluation apparatus according to claim 1,
The imaging means includes a light source unit for irradiating light toward the sample to be evaluated, and a light receiving unit for receiving light irradiated from the light source unit and reflected by the sample to be evaluated.
The incident angle of the light irradiated by the light source unit to the sample to be evaluated and the emission angle of the light irradiated from the light source unit and reflected by the sample to be evaluated are 0 °. Gloss unevenness evaluation device. In the gloss nonuniformity evaluation apparatus as described in any one of Claims 2 thru | or 5,
The gloss unevenness evaluation apparatus, wherein the light irradiated by the light source unit and incident on the sample to be evaluated is parallel light. In the gloss unevenness evaluation apparatus according to any one of claims 1 to 6,
The first calculation means calculates the glitter component and the color component using a CIE color system,
The gloss component calculated by the first calculation means is an L ^* value of the CIE color system, and the degree used by the fourth calculation means is whiteness or c ^* value. Unevenness evaluation device. A first calculation step of calculating a brightness component and a color component of a pixel included in the image captured by the imaging step capable of capturing an image including specularly reflected light of the sample to be evaluated;
A second calculation step of calculating an average value of the glitter component and an average value of the color component calculated by the first calculation means;
A third calculation step of calculating a predetermined value by performing a weighting process considering human visual characteristics and integrating the spatial frequency characteristic of the deviation from the average value of the luminous component calculated by the second calculation means; ,
A gloss unevenness evaluation value is calculated by performing a weighting process on the predetermined value calculated by the third calculation unit with the degree of color using the average value of the color components calculated by the second calculation unit. A gloss unevenness evaluation method using the fourth calculation step.   An image forming apparatus comprising the gloss unevenness evaluation apparatus according to claim 1 or using the gloss unevenness evaluation method according to claim 8.   A computer-readable recording medium storing a program for executing the gloss unevenness evaluation method according to claim 8.

Images