JP2010211055A - Image forming apparatus, image forming method, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more accurately perform control of a fixing condition using surface diffused light by: measuring the surface diffused light with good accuracy even when a toner adhesion amount is varied; and measuring the surface diffused light by using paper to be actually used by a user. <P>SOLUTION: A fixing device 30 fixes a patch image transferred to recording material. A spectral colorimeter 41 measures a spectral reflectance factor 1 of the fixed patch image. The recording material is restored to the front side of the fixing device 30 by a transfer roller, and a transparent toner image is transferred to the recording material through a transfer belt. The recording material passes through the fixing device 30 again, whereby the transparent toner image is fixed on the patch image. Then, a spectral reflectance factor 2 is measured by the spectral colorimeter 41, the measured spectral reflectance factors 1 and 2 are input in an image characteristic acquiring part 150, and the surface diffused light is calculated. A fixing condition controller 110 controls a fixing condition (temperature) based on the calculated surface diffused light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a color copying machine, a color printer, and a color FAX using an electrophotographic system, and a fixing condition setting method.

  In recent years, color image forming apparatuses such as color printers and color copiers are required to improve the output image quality. In an electrophotographic image forming apparatus configured as a printer, a copier, a facsimile, or a complex machine thereof, an electrostatic latent image is written by irradiating light onto a photosensitive drum charged by a charging device. By supplying toner to the photosensitive drum by a developing device, the electrostatic latent image is developed as a toner image (forming a toner image), and the toner image is directly on a predetermined recording material such as recording paper or in the middle An image forming process is performed in which the image is indirectly transferred via an intermediate recording material such as a transfer belt and finally heated and fixed by a heating roller or the like provided in the fixing device.

  Such an image forming apparatus is formed on a recording sheet due to a change in toner adhesion amount or toner image fixability due to a change in an environment in which the apparatus is installed or aged deterioration of a photosensitive drum or a developer. The color reproducibility and glossiness typified by the image density vary. Therefore, a method is widely used in which the image density and glossiness are monitored and the results are fed back to control the density and glossiness so that the desired density and glossiness can be obtained even if each part of the apparatus fluctuates. . There are the following techniques as conventional examples related to these.

  For example, the density of the image before and after fixing of the control patch image to be output and the glossiness of the image after fixing are measured, and the density control value (image forming condition) is determined from the density measurement result, and the density There is an apparatus for controlling the gloss control value (fixing condition) based on the control value and the measurement result of the gloss level (see, for example, Patent Document 1).

  Similarly, there is also an apparatus for determining the density and the glossiness by measuring the density of the control patch before and after fixing the toner image, and controlling the image forming conditions and the fixing conditions based on them (for example, Patent Document 2). See).

  Here, the image forming conditions are, for example, a setting value of a developing bias potential, a setting value of a charging potential of an image carrier (photosensitive member), an exposure intensity for the image carrier (exposure intensity for writing an electrostatic latent image) One or a plurality of set values of the ratio between the peripheral speed of the rotating image carrier and the peripheral speed of the developing roller rotating opposite to this (so-called peripheral speed ratio). And mainly relates to control of the toner adhesion amount. The fixing conditions include, for example, one or a plurality of fixing temperatures, nip pressures, and recording material conveyance speeds, and mainly relate to control of fixing properties.

  However, the conventional technique for controlling the fixing conditions using the above-described glossiness and density as target values has a problem that a desired color cannot be reproduced for the following reasons.

  First, it will be explained that the color reproducibility depends not only on the toner adhesion amount but also on the fixing property. When the image is irradiated with light in a normal colorimetry system and the reflected light is measured, the reflected light to be measured includes surface diffused light reflected from the image surface and reflected light from the toner layer. Yes. When this surface diffused light increases, the light reflected without touching the color material inside the toner layer increases, and the reproducible color space becomes smaller (the color becomes dull).

  FIG. 17A shows the relationship between surface diffused light and saturation. FIG. 17A shows how the saturation decreases as the surface diffused light increases. Thus, it can be seen that the color reproducibility depends on the surface diffused light. Since this surface diffused light depends on the surface state of the image, that is, the fixability, it can be seen that the color reproducibility depends on the fixability.

  FIG. 18 is a diagram for explaining the measurement principle of the surface diffused light. FIG. 18A shows how the reflectance of a toner image is measured by a measurement system of 0/45 ° (0 ° incidence, 45 ° light reception). At this time, the reflected light 201 to be measured includes reflected light (surface diffused light) 201 a from the surface of the toner layer 212 and reflected light (internally reflected light) 201 b from the inside of the toner layer 212. Reference numeral 211 denotes a recording material.

  On the other hand, FIG. 18B shows a state in which a transparent film 213 having a mirror-like surface is optically adhered to the surface of the toner image of FIG. 18A, and is measured using the same optical system as in FIG. Show. Here, the A layer and the B layer are in optical contact refers to a state in which there is no air layer between them and the interface between them is optically continuous. At this time, the reflected light 202a on the surface in FIG. 18B is specularly reflected because the surface is in a mirror state as described above, and is reflected in the 0 ° direction. Further, as described above, the toner layer 212 and the transparent film 213 are in optical contact, and no air layer or the like exists between them. Further, it is preferable that the refractive indexes are equal to prevent reflected light from being generated at the interface between the toner layer 212 and the transparent film 213. Therefore, at this time, the reflected light 202 received is only the internally reflected light 202b. Since the internally reflected light 201b and 202b are equal, by subtracting 202 from the measured value 201, the internally reflected light is canceled and the surface diffused light 201a can be obtained. The surface diffused light thus obtained can be directly incorporated into the color evaluation because the color colorimetry system and the measurement system are equal as described above.

  As described above, when the fixing property changes due to deterioration of the apparatus over time, it is desirable that the fixing conditions can be controlled so that the target color reproduction can be maintained. However, as described above, the conventional technique of measuring the glossiness and density and controlling the fixing conditions cannot achieve the desired color reproduction.

  First, since the glossiness differs in color and measurement system, the color cannot be directly evaluated from the glossiness. FIG. 19 shows a measurement optical system for glossiness and color. FIG. 19A shows a glossiness measurement system, and FIG. 19B shows a color measurement system. As shown in FIG. 19A, the gloss level measures specularly reflected light, whereas as shown in FIG. 19B, the color measures diffuse light. Accordingly, the glossiness is not directly related to the color and cannot be used for the evaluation of the color (note that the 0/45 ° system (0 ° incidence, 45 ° light reception) is shown in FIG. 19B. The system also includes 0 / d (measurement with an integrating sphere), etc. In any case, the color measurement system measures diffuse light).

  Further, the glossiness has no one-to-one correlation because the measurement system is different from the surface diffused light using the same measurement system as the color. FIG. 17B shows the relationship between glossiness and surface diffused light. Glossiness measures specular reflection light as described above, and is related to surface irregularities, but as shown in FIG. 17B, surface diffused light is not uniquely determined for a certain glossiness, It has some width. Therefore, the surface diffused light cannot be controlled by the glossiness. As described above, the target color can be reproduced by controlling the surface diffused light. However, since the glossiness cannot control the surface diffused light, the target color cannot be reproduced indirectly by the glossiness.

  Next, when the density is used for controlling the fixing conditions, since the density is calculated only from the average value of the spectral reflectance or the value of the absorption band, the L * a * b * value representing the color is uniquely determined by the density. I can't. That is, even if the density is controlled to a desired value, the L * a * b * value of the reproduced color may be deviated, so that the target color cannot be controlled. Even if the spectral reflectance (spectral density) is measured and used for control, the spectral reflectance is a value including both internally reflected light and surface diffused light, that is, fluctuation in toner adhesion amount and fixability. Including both fluctuations. Therefore, when the density changes, it cannot be determined whether the toner adhesion amount fluctuation or the fixing property fluctuation is caused, and appropriate control cannot be performed.

  Accordingly, the present applicant has previously proposed an image forming apparatus that measures surface diffusion light from a patch image transferred and fixed on a recording material and controls fixing conditions based on the measured surface diffusion light. Proposed an image forming apparatus / method capable of obtaining a desired color reproduction by controlling fixing conditions based on the above (Japanese Patent Application No. 2008-238089).

  By the way, in the method proposed above, the reflection characteristic of the non-specular state corresponding to FIG. 18A is applied to the created patch image using a spectrocolorimeter or the like in the measurement principle of the surface diffused light shown in FIG. On the other hand, the reflection characteristic 2 in the specular state shown in FIG. 18B measured in advance is stored in the memory in advance, and the surface diffused light is calculated from the reflection characteristics 1 and 2. This method is based on the assumption that the toner adhesion amount does not vary.

  However, in an actual image forming apparatus, the toner adhesion amount also varies depending on the environment in which the apparatus is installed and the aging of the apparatus. At this time, the reflection characteristic 1 changes according to the fluctuation of the toner adhesion amount, but the reflection characteristic 2 stored in the memory does not follow the fluctuation of the toner adhesion amount and remains constant. Originally, the measurement principle of the surface diffused light shown in FIG. 18 is based on the premise that the toner images of (a) and (b) are the same. Since both are the same, even if the toner adhesion amount fluctuates, the fluctuation amount is common to both, so it is canceled out when the difference is taken, and the surface diffused light can be obtained correctly.

  However, in the previously proposed method, the reflection characteristics in the mirror state corresponding to FIG. 18B are handled as being fixed, so that fluctuations in the toner adhesion amount cannot be absorbed, and the surface diffused light enters as noise. End up. As a result, there has been a problem that the surface diffused light cannot be measured correctly when the toner adhesion amount fluctuates.

  In order to solve the above-described problems, the present applicant first outputs a patch image having a toner area ratio of 100% on a transparent film (hereinafter referred to as an OHP sheet), measures the reflection characteristics from the front and back surfaces, A technique for acquiring surface diffused light by taking the difference between the two was proposed (Japanese Patent Application No. 2009-054853). In this method, since the surface diffused light is obtained only from the actually measured patch value, even if there is a change in the toner adhesion amount, a result following it can be obtained.

  In the proposed method, an OHP sheet is used for measuring the surface diffused light. However, since the thermal conductivity of the OHP sheet and the paper is different, even if the fixing conditions are the same, the OHP sheet and the paper Fixing state will be different. Therefore, even if the surface diffused light is controlled by the above-described method, it is not always applicable to the case where the optimum value at that time is paper. In view of the fact that image forming apparatuses are required to have higher image quality, it is desired to develop a technique with higher measurement accuracy of surface diffused light.

The present invention has been made in view of the above problems,
The object of the present invention is to use surface diffused light by accurately measuring surface diffused light and measuring the surface diffused light using paper actually used by the user even when the toner adhesion amount fluctuates. It is an object of the present invention to provide an image forming apparatus, method, program, and recording medium for performing the fixing condition control with higher accuracy.

  The present invention provides an image forming means for forming a patch image with a toner area ratio of 100% and transferring it to a recording material, a fixing means for fixing the patch image transferred to the recording material under a predetermined fixing condition, and the fixing. A surface diffused light acquiring means for obtaining surface diffused light from the patch image; an adhesion amount acquiring means for obtaining a toner attached amount of the patch image; and the predetermined amount based on the acquired surface diffused light and toner attached amount. And a control means for controlling the fixing conditions.

  According to the present invention, even if the toner adhesion amount fluctuates, the surface diffused light can be accurately measured, and the surface diffused light is measured using the paper that the user actually uses. Fixing condition control using diffused light can be performed with higher accuracy.

The system configuration | structure of Example 1 of this invention is shown. 1 illustrates a configuration of an image forming unit according to a first exemplary embodiment. The relationship between the toner adhesion amount and the density of the mirror surface state is shown. The structural example of the spectral colorimeter of Example 1 is shown. 3 is a flowchart illustrating a fixing condition control operation according to the first exemplary embodiment. An example of a patch image is shown. The table referred in Example 1 is shown. The relationship between fixing temperature and surface diffused light is shown. The system configuration | structure of Example 2 is shown. 2 illustrates a configuration of an image forming unit according to a second exemplary embodiment. The spectral reflectances of cyan and yellow are shown. The relationship between the color toner adhesion amount and the diffuse reflected light output voltage is shown. 9 is a flowchart illustrating a fixing condition control operation according to the second exemplary embodiment. The system configuration | structure of Example 3 is shown. 3 shows a configuration of an image forming unit according to Embodiment 3. 9 is a flowchart illustrating a fixing condition control operation according to the third exemplary embodiment. It is a figure explaining the prior art (relationship between surface diffused light and saturation). It is a figure explaining prior art (measurement of surface diffused light). It is a figure explaining a prior art (measurement optical system).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An example in which a transparent toner is used as the smoothing unit of Example 1 will be described. FIG. 1 shows a system configuration of Embodiment 1 of the present invention. In FIG. 1, reference numeral 100 denotes an image forming unit having a paper feeding unit 21, a writing optical system 24, an image forming unit 103 that forms a toner image on a photosensitive drum by a process step according to an electrophotographic process, and transfers the toner image to a recording material. A fixing condition control unit 120 includes a driver 111 that controls predetermined fixing conditions, for example, a driver 111 that energizes a heater so as to reach a predetermined fixing temperature, a storage unit 112 that stores fixing conditions, and the like. , A main control unit that controls the entire image forming apparatus; 130, an image processing unit that executes various image processing; 140, an operation display unit that has a function of displaying various input settings and the state of the apparatus; A memory 151 for storing data to be described later, an image characteristic acquisition unit 30 having a calculation unit 152 for calculating surface diffused light, toner adhesion amount, and the like. A fixing device having such pressure roller 32, 41, described later spectrophotometer, 33, 34 heater, 35a, b is a thermistor for detecting the fixing temperature. In the present exemplary embodiment, the configuration in which the image forming unit 100 and the fixing device 30 are combined also serves as a smoothing unit that performs a smoothing process on the surface of the toner image.

  FIG. 2 shows the configuration of the image forming unit 100, the fixing device 30, and the spectrocolorimeter 41 shown in FIG. 1 in detail. The apparatus shown in FIG. 2 is a tandem color image forming apparatus that employs an intermediate transfer member 27, which is an example of an electrophotographic color image forming apparatus, but may have other configurations such as a revolver color image forming apparatus. .

  This color image forming apparatus includes a paper feeding unit 21, photosensitive members (22W, 22Y, 22M, 22C, and 22K) arranged in parallel for development colors, and injection charging means (23W, 23Y, 23M, and 23C) as primary charging means. 23K), toner cartridge (25W, 25Y, 25M, 25C, 25K), developing means (26W, 26Y, 26M, 26C, 26K), intermediate transfer member 27, transfer roller 28, cleaning means 29, fixing device 30, spectral device A colorimeter 41 is provided.

  Next, the operation of the color image forming apparatus shown in FIGS. This operation is comprehensively controlled by the main control unit 120. The image forming unit 100 forms an electrostatic latent image by irradiating the charged photosensitive drum with exposure light by the writing optical system 24 based on the exposure time converted by the image processing unit 130. Is developed to form a single color toner image, the single color toner images are superimposed to form a multicolor toner image, the multicolor toner image is transferred to the recording material 11, and the multicolor toner image on the recording material 11 is transferred. Is fixed by the action of heat and pressure.

  In FIG. 2, photosensitive drums 22W, 22Y, 22M, 22C, and 22K are configured by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder, and are rotated by the driving force of a driving motor (not shown) being transmitted. The drive motor rotates the photosensitive drums 22W, 22Y, 22M, 22C, and 22K in the counterclockwise direction according to the image forming operation.

  As primary charging means, five chargers 23W, 23Y for charging the photosensitive drums of transparent (W), yellow (Y), magenta (M), cyan (C), and black (K) for each station. Each charger is provided with a sleeve 23WS, 23YS, 23MS, 23CS, and 23KS.

  Exposure light to the photosensitive drums 22W, 22Y, 22M, 22C, and 22K is sent from the writing optical systems 24W, 24Y, 24M, 24C, and 24K, and the surfaces of the photosensitive drums 22W, 22Y, 22M, 22C, and 22K are selected. It is configured so that an electrostatic latent image is formed by performing exposure periodically.

  As developing means, in order to visualize the electrostatic latent image, five developments are performed to develop transparent (W), yellow (Y), magenta (M), cyan (C), and black (K) for each station. The developing devices 26W, 26Y, 26M, 26C, and 26K are provided, and the developing devices are provided with sleeves 26WS, 26YS, 26MS, 26CS, and 26KS, respectively. Each developing device is detachably attached.

  The intermediate transfer member 27 is in contact with the photosensitive drums 22W, 22Y, 22M, 22C, and 22K, and rotates in the clockwise direction when forming a color image, thereby rotating the photosensitive drums 22W, 22Y, 22M, 22C, and 22K. Along with this, the single color toner image is transferred. Thereafter, a transfer roller 28 (to be described later) comes into contact with the intermediate transfer member 27 to sandwich and convey the recording material 11, and the multicolor toner image on the intermediate transfer member 27 is transferred to the recording material 11.

  The transfer roller 28 contacts the recording material 11 at the position 28a while transferring the multicolor toner image onto the recording material 11, and is separated to the position 28b after the printing process.

  The fixing device 30 melts and fixes the transferred multi-color toner image while conveying the recording material 11. As shown in FIGS. 1 and 2, the fixing device 30 includes a fixing roller 31 that heats the recording material 11 and the recording material 11. A pressure roller 32 for press-contacting the fixing roller 31 and thermistors (thermometers) 35a and 35b are arranged on the surfaces of these rollers in a state where they are in contact with each other with a slight pressure. The fixing roller 31 and the pressure roller 32 are formed in a hollow shape, and heaters 33 and 34 are incorporated therein, respectively. That is, the recording material 11 holding the multicolor toner image is conveyed by the fixing roller and the pressure roller, and heat and pressure are applied to fix the toner on the surface. Further, the fixing temperature at that time is successively monitored by the thermistor 35. Although the number of thermistors is two, a plurality of thermistors may be arranged for reasons such as device configuration and accuracy improvement. The monitored temperature value is fed back to the fixing condition control unit 110.

  The recording material 11 on which the toner image has been fixed is discharged to a discharge tray (not shown) by a discharge roller (not shown), and the image forming operation is completed. The cleaning unit 29 cleans the toner remaining on the intermediate transfer member 27. Waste toner after the transfer of the five-color toner image formed on the intermediate transfer member 27 to the recording material 11 is stored in a cleaner container. Stored in

  Next, with reference to FIG. 1, the outline of the control operation of the fixing conditions in the image forming apparatus will be described. This image forming apparatus includes an image processing unit 130 including a memory for storing image forming conditions and patch images, an IC for performing image processing, a fixing condition control unit 110 for storing and controlling fixing conditions, and an image forming unit. 100 and a smoothing processing unit including the fixing device 30 is included.

  As described above, the toner image is transferred to and fixed on the recording material 11. In this embodiment, a patch image (see FIG. 6A) is formed on the recording material 11 to perform transfer and fixing. The spectral reflectance 1 of the patch image after fixing is measured by the spectrocolorimeter 41. Subsequently, the surface of the patch image is smoothed by transferring and fixing a transparent toner image (see FIG. 6B) so as to be superimposed on the patch image, and then the spectral colorimeter 41 uses a spectral reflectance of 2 Measure. Then, these spectral reflectances 1 and 2 are input to the image characteristic acquisition unit 150 to calculate surface diffused light. Subsequently, the fixing condition control unit 110 controls the fixing conditions according to information from the image characteristic acquisition unit 150.

  The operation of each part until the acquisition of the surface diffused light will be described in more detail with reference to FIG. Each color patch image created on the photosensitive drum 22 is transferred to the recording material 11 via the transfer belt 27. Then, after heat fixing by the fixing device 30, the spectral reflectance 1 is measured by the spectral colorimeter 41. Thereafter, the recording material 11 is returned to the front side from the transfer roller 28 by the reverse rotation of the conveying roller 35. Subsequently, a transparent toner image is now created on the photosensitive drum 22 </ b> W and transferred to the recording material 11 via the transfer belt 27. Then, when the recording material 11 passes through the fixing device 30 again, the transparent toner image is fixed on the patch image. Thereafter, the spectral reflectance 2 is measured by the spectrocolorimeter 41, and the measured spectral reflectances 1 and 2 are input to the image characteristic acquisition unit 150 to calculate surface diffused light.

  After the spectral reflectance 1 is measured by the spectrocolorimeter 41, the recording material 11 passes through the fixing device 30 in the reverse direction. At this time, the surface of the patch image is melted by heat and pressure applied from the fixing device 30. However, the surface shape may change. However, a transparent toner image is formed on the surface of the patch image, and after the surface is smoothed, the spectral reflectance 2 in the mirror state is measured. That is, since the transparent toner layer is formed on the surface of the patch image, only the thickness of the toner layer of the patch image is related to the measurement of the spectral reflectance 2, and the surface shape of the patch image is not related. Therefore, there is no problem even if the surface state of the patch image changes when the recording material 11 passes through the fixing device 30 in the reverse direction.

  In this embodiment, a layer made of transparent toner is further formed on the patch image as a smoothing process for the surface of the created patch image. By superimposing transparent toner on the CMYK toner layer of the patch image, the thickness of the toner layer is increased and the surface is smoothed. The state where the transparent toner image is superimposed on the patch image corresponds to (b) of FIG. 18 showing the measurement principle of the surface diffused light. That is, in FIG. 18, the spectral reflectance 1 corresponds to 201, and the spectral reflectance 2 corresponds to 202. Therefore, as described above, the surface diffused light can be calculated by taking the difference between the two.

  When calculating the surface diffused light, precisely, since the reflected light 202 (spectral reflectance 2 of this embodiment) in FIG. 18B passes through the transparent film layer (transparent toner layer of this embodiment), The reflectance 202 needs to be corrected (divided) for the transmittance of the transparent film layer. That is, it is necessary to correct the spectral reflectance 2 of this embodiment with the transmittance of the transparent toner layer. As described above, the amount of adhesion of the transparent toner image formed on the patch image may fluctuate. However, since the transparent toner generally has a high transmittance, the amount of adhesion of the transparent toner varies slightly. However, since the transmittance of the transparent toner layer hardly changes, in this embodiment, only the transmittance at the reference adhesion amount of the transparent toner is stored in the memory 152, and the spectral reflectance 2 is corrected by using the memory 152.

  That is, R ′ = R / T ^ (1 + √2) (^ is a power) where R is spectral reflectance 2, T is the transmittance of the transparent toner layer, and R ′ is the corrected spectral reflectance 2. ). This is because the incident light enters the patch image (transparent toner image) from the 0 ° direction, passes through the transparent toner layer, is reflected inside the patch image, and then the reflected light reflected in the 45 ° direction is again the transparent toner. It represents passing through a layer.

  Further, since the surface state when the transparent toner image is superimposed on the patch image needs to be close to the mirror state as shown in FIG. 18B, the fixing when fixing the transparent toner image is performed. The conditions are different from the patch image fixing conditions. That is, a value that is as close to the mirror surface as possible is obtained in advance, and the value is stored in the storage unit 112.

  For example, as shown in FIG. 8, when the fixing temperature is taken on the horizontal axis and the surface diffused light is taken on the vertical axis, the graph draws a downwardly convex curve (the reason will be described later). However, the smaller the surface diffused light, the closer the surface becomes to the mirror surface state, and the minimum point in FIG. 8 is the fixing temperature closest to the mirror surface state. Therefore, the fixing temperature at the minimum point may be obtained in advance by experiments and stored in the storage unit 112.

  The image characteristic acquisition unit 150 inputs measurement values of the spectral colorimeter 41 that measures the spectral reflectances 1 and 2 from the image fixed on the recording material, and the calculation unit 152 has the spectral reflectance 1 and the spectral reflectance 2. And the surface diffused light is calculated. At the time when the difference is calculated, the surface diffused light is spectral data, but for the sake of convenience of comparison with the upper limit as described later, the average value of the values in the toner absorption band of the patch image is set to a single value. The calculated value is used as surface diffused light. The absorption band is used because the absorption band is least affected by the transmittance of the transparent toner layer.

  Further, the image characteristic acquisition unit 150 calculates the toner adhesion amount of the patch image from the input spectral reflectance 2 (after correcting the transmittance of the transparent toner layer). The reason why the toner adhesion amount is obtained is that the appropriate value of the surface diffused light varies depending on the toner adhesion amount of the patch image (see FIG. 7). Therefore, the surface diffusion light is calculated by the image characteristic acquisition unit 150 as described above, and at the same time, the target value (upper limit value) of the surface diffusion light is acquired from the toner adhesion amount of the patch image, and the two are compared, thereby comparing the surface diffusion. It is determined whether the light is appropriate.

  FIG. 3 shows the relationship between the toner adhesion amount and the density of the mirror surface state. If the surface condition after smoothing is an ideal mirror surface, the relationship is as shown by the solid line in the figure, but in reality, some irregularities remain after the smoothing process, so the relationship as shown by the broken line in the figure It becomes.

  In the image characteristic acquisition unit 150, the relationship of FIG. 3 when the surface of the patch image is smoothed with the transparent toner is measured in advance and stored in the memory 152, and the input spectral reflection is input using the measured relationship. A method of obtaining the density of the mirror surface state from the rate 2 and converting it to the toner adhesion amount corresponding to the density is used.

  The spectrocolorimeter 41 is disposed downstream of the fixing device 30 in the recording material conveyance path toward the image forming surface of the recording material 11, and the spectral reflectance 1 from the fixed image formed on the recording material 11 is 1. 2 is detected. By disposing the spectrocolorimeter 41 inside the color image forming apparatus, it is possible to automatically detect the fixed image before discharging it to the paper discharge unit.

  FIG. 4A shows a configuration example of the spectrocolorimeter 41. The spectrocolorimeter 41 processes a light source 51 such as a halogen lamp, a shaping lens 52 such as a collimator lens, a spectral element 54 such as a slit 53, a concave diffraction grating, a light receiving element 55 such as a C-MOS sensor, and light reception data. It is configured by an IC (not shown).

  The light source 51 and the lens 52 are arranged on a straight line perpendicular to the surface of the recording material 11 and irradiate the recording material 11 perpendicularly. The slit 53 and the spectroscopic element 54 are arranged in a direction of 45 ° with respect to the direction perpendicular to the recording material surface. Of the reflected light from the measurement object, the light reflected in the 45 ° direction passes through the slit 53 and then is split. The light is dispersed by the element 54 and received by the light receiving element 55. The light trap is installed on the side opposite to the incident direction, and absorbs light transmitted through the recording material 11. In this embodiment, 0/45 ° is used, but an integrating sphere such as 0 / d (SCE) may be used as described above.

  In this way, the spectral reflectance 1 is measured by the spectral colorimeter 41 with respect to the patch image fixed on the recording material 11, and sent to the calculation unit 152. Thereafter, the transparent toner image is transferred and fixed on the patch image on the recording material 11, and the spectral reflectance 2 is measured by the spectrocolorimeter 41 with respect to the image after fixing and sent to the calculation unit 152. The calculation unit 152 calculates the surface diffused light by taking the difference between the spectral reflectance 1 and the spectral reflectance 2. Then, the calculation result is sent to the fixing condition control unit 110, and the fixing condition control unit 110 controls the fixing conditions based on the sent data.

  As the transparent toner, fine particles formed using a binder resin used for manufacturing color toners are used. Specifically, it is used for general toners such as polyester resins, polystyrene resins, polyacrylic resins, other vinyl resins, polycarbonate resins, polyamide resins, polyimide resins, epoxy resins, polyurea resins, etc. Known resins and polymers thereof can be used. As described above, since the surface when the transparent toner is fixed is preferably as close to a mirror surface as possible, the transparent toner may be made of the same material as the color toner, but is more easily melted under the same fixing conditions. Such a configuration may be adopted.

  FIG. 5 is a flowchart of the fixing condition control operation according to the first embodiment. The fixing condition control operation controls the fixing condition using a patch image formed on the recording material 11 and is controlled by the main control unit 120 and the fixing condition control unit 110.

  First, the patch image is transferred to the recording material 11 and fixed (step S1). Subsequently, the spectral reflectance 1 from the fixed patch image is measured (step S2). Next, a transparent toner image is transferred and fixed on the patch image (step S3), and the spectral reflectance 2 is measured (step S4). Then, the surface diffused light and the toner adhesion amount of the patch image are calculated from the spectral reflectances 1 and 2 (step S5).

  Subsequently, the upper limit value of the surface diffused light corresponding to the toner adhesion amount calculated in S5 is read from the storage unit 112, and it is determined whether or not the acquired surface diffused light is equal to or lower than the upper limit value (step S6). When the surface diffused light is equal to or less than the upper limit value, a series of this process is terminated. On the other hand, if the surface diffused light is not less than or equal to the upper limit value, it is further determined whether there is room for control of fixing conditions (step S7). If there is room for control of fixing conditions, the fixing conditions are controlled (step S8). ), The process returns to step S1, and the above-described operation is repeated.

  As described above, the operation for controlling the fixing conditions based on the acquired surface diffused light is started upon receiving a request for controlling the fixing conditions from the user, or when a predetermined number of sheets are printed, the fixing condition control is automatically performed. You may start. Further, the fixing condition control may be started at the time of fixing adjustment at the time of shipment from the factory, at the time of maintenance and inspection by a service person (particularly when the fixing device and the roller are replaced), and the like. Further, the control (setting) of the fixing condition may be performed by an instruction from the operation display unit 140 or a special operation by a service person having a specific technique.

  In steps S 1 and S 3, control patch data is sent from the storage unit 112 to the image processing unit 130, patches are formed on the recording material 11, and toner is heated and fixed by the fixing device 30. Here, the fixing conditions used for heat fixing in step S <b> 1 are the latest fixing conditions stored in the storage unit 112. On the other hand, the fixing conditions used for heat-fixing the transparent toner image in step S3 are constant as described above, unlike the fixing conditions in step S1.

  FIG. 6A shows an example of a patch image that is heat-fixed on the recording material 11. In FIG. 6A, patches having a C, M, Y, and K monochromatic area ratio of 100% are arranged in a line in the conveyance direction of the recording material 11. The reason for using only a patch with an area ratio of 100% is that a patch with an area ratio of 100% is optimal for confirming a change in fixability. Of course, instead of a single color, a patch with an area ratio of 100% for secondary colors such as R, G, and B may be used. Further, the reason why the fixing members 30 are arranged in a line in the conveyance direction of the recording material 11 is because a case where the fixing device 30 has fixing unevenness in a direction (main scanning direction) perpendicular to the conveyance direction of the recording material 11 is considered. It is. In FIG. 6A, one patch is arranged for each color. However, in order to improve measurement accuracy, a plurality of patches of the same color may be arranged, and surface diffused light may be obtained for each patch by a method described later, and an average may be taken. .

  FIG. 6B shows an example of a transparent toner image that is heat-fixed on the recording material 11. In FIG. 6B, patches having the same position and shape as the patches of each color in FIG. 6A are arranged, and a transparent toner image is formed so as to overlap the patch image in FIG. 6A. .

  In FIG. 5, steps S2 to S6 for acquiring the surface diffused light and comparing it with the upper limit value will be further described. In step S <b> 2, the spectral reflectance 1 is measured by the spectrocolorimeter 41 for each color patch heat-fixed on the recording material 11. In step S <b> 4, the spectral reflectance 2 is measured by the spectrocolorimeter 41 for the transparent toner image heated and fixed on the patch image on the recording material 11. In step S <b> 5, the surface diffused light is calculated by calculating the difference between the spectral reflectance 1 and the spectral reflectance 2 in the calculation unit 152. In step S6, the calculated surface diffused light is compared with the upper limit value of the surface diffused light stored in advance in the memory 151 for each color. As a result of the comparison, if the surface diffused light is equal to or less than the upper limit value, the series of processes in FIG. 5 ends. On the other hand, if it is determined that the surface diffused light is not less than or equal to the upper limit value, the surface diffused light and the upper limit value or a difference value thereof are sent to the fixing condition control unit 110.

  FIG. 7 shows an example of a data table read from the memory 112 in step S6 of FIG. The data table in FIG. 7 includes the type of the recording material and the upper limit value of the surface diffused light for each toner adhesion amount. As described above, the image characteristic acquisition unit 150 calculates the toner adhesion amount of the patch image, and obtains the upper limit value of the surface diffused light from the data table of FIG. 7 according to the calculation result. In the table of FIG. 7, data is stored for one type of recording material, but data may be stored for a plurality of recording materials in order to improve convenience for the user.

  In steps S7 and S8 in FIG. 5, the fixing conditions are controlled based on the sent data. First, in step S7, it is determined whether there is room for control in the fixing conditions (usually, it is determined that there is room in the first cycle). Here, there is room for control in the fixing conditions means that the surface diffused light can be further reduced by appropriately controlling the fixing conditions. If it is determined that there is room for control, the fixing conditions are controlled in step S8. Then, after updating the fixing condition stored in the storage unit 112 to the latest value, the process returns to step S1 and the control flow is executed again.

  Hereinafter, specific examples of the fixing condition control in steps S7 and S8 will be described. The aim of fixing condition control is to reduce the surface diffused light and keep it below the upper limit. Examples of the fixing conditions to be controlled include a fixing temperature, a nip pressure, and a recording material conveyance speed. Here, the nip pressure and the conveyance speed are constant, and the fixing temperature, which is the surface temperature of the fixing roller 31 and the pressure roller 32 detected by the thermistors 35a and 35b, is considered as a control target.

  FIG. 8 shows the change of the surface diffused light with respect to the fixing temperature. As shown in FIG. 8, the surface diffused light has a downwardly convex curve with respect to the fixing temperature. The reason is that in the region where the fixing temperature is low, the toner is not sufficiently melted and a lot of irregularities remain on the surface, so that the surface diffused light becomes large. As the fixing temperature is raised, the toner is sufficiently melted, surface irregularities are reduced, and surface diffused light is reduced. However, if the fixing temperature is raised above a certain level, this time, hot offset begins to occur, peeling occurs on the toner surface, resulting in unevenness, resulting in an increase in surface diffused light. Therefore, in order to reduce the surface diffused light, the fixing temperature may be controlled so as to approach the minimum point of the curve in FIG.

  The significance of determining whether there is room for control in the fixing condition in step S7 in FIG. 5 will be described. Even if the fixing property is deteriorated due to aging of each component constituting the fixing device 30 and the surface diffused light is made as small as possible by the method described later (even if the local minimum point in FIG. 8 is reached), the surface diffusion is reduced. There may be a case where the light value exceeds the upper limit value of the surface diffused light stored in the memory 151 described above. Step S7 is a processing step considering such a case. Even if it is determined in step S6 that the surface diffused light exceeds the upper limit value, if it is determined in step S7 that the surface diffused light has reached the minimum point, step S7 is performed. The control flow of the fixing conditions in FIG.

  As described above, the control of the fixing temperature is to control the fixing temperature so as to be close to the minimum point in FIG. 8, but the fixing roller 31 and the pressure roller 32 are deteriorated over time. Even if they are the same, the value of the surface diffused light is not always the same. Further, the fixing temperature measured by the thermistors 35a and 35b cannot always be measured in the same manner, and the measured value varies from time to time. Therefore, the curve in FIG. 8 is only relative and varies from time to time. That is, controlling the fixing temperature means bringing the temperature close to the temperature corresponding to the minimum point in FIG. Therefore, for example, it is meaningless to store the temperature of the minimum point in FIG. 8 in advance and control the fixing temperature using the temperature as a target value, and the minimum point in FIG. It is necessary to determine and control the current position with respect to.

  Hereinafter, an example of the fixing temperature control method will be described. First, considering that the rough characteristics (the magnitude of the differential coefficient, etc.) of the curve in FIG. 8 do not change, a predetermined temperature ΔT that is changed during fixing temperature control is stored in the storage unit 112 in advance. Then, a patch image is output under the latest fixing conditions (fixing temperature) once stored in the storage unit 112, surface diffusion light is measured, and the measured surface diffusion light is temporarily stored in the storage unit 112. . If the surface diffused light exceeds the upper limit value in step S6 in FIG. 5, the fixing temperature is changed by ΔT, the process returns to step S1, the patch image is output again, and the surface diffused light is measured. Then, the measured surface diffused light and the surface diffused light in the immediately preceding cycle stored in the storage unit 112 are compared. If the surface diffused light is reduced at this time, it can be seen that the minimum point in FIG. 8 has been approached, so the fixing temperature may be controlled in that direction. On the other hand, if the surface diffused light is increased, it can be seen that the surface diffused away from the minimum point, and thus the fixing temperature may be controlled in the opposite direction. In this way, the relative position at the present time with respect to the minimum point in FIG. 8, that is, the direction in which the fixing temperature is controlled is obtained, and the above cycle is stored in the memory 151 until the surface diffused light becomes sufficiently small, that is, What is necessary is just to repeat until it falls below an upper limit or the minimum point in FIG.

  The predetermined temperature ΔT is a temperature that is neither excessive nor excessive. In other words, once the fixing temperature is changed by ΔT, ΔT is too large so as to jump over the minimum point. On the other hand, if ΔT is too small, the fixing condition control flow is repeated many times. However, the cycle must be repeated, and time and costs are wasted. ΔT is desirably large when the fixing temperature is far from the minimum point, and is small when close to the minimum point. Therefore, this ΔT may be input manually, for example, by a serviceman every time the control flow cycle shown in FIG. 5 is performed, and in the case of automatic control, an optimal control method for this ΔT is selected in advance. It is desirable to store in the storage unit 112.

  When the surface diffused light always exceeds the upper limit value of the surface diffused light stored in the memory 151 due to deterioration of the fixing device 30 or the like (in step S7, it is determined that there is no room for control in the fixing condition). In other words, a method of updating the upper limit value of the surface diffused light stored in the memory 151 to a value at the minimum point in FIG. As a result, when the surface diffused light always exceeds the upper limit value (before update), the update is performed every time the control flow of the fixing conditions is started when the update is not performed. A cycle of searching for the minimum point in FIG. 8 by changing the temperature can be omitted. This is because if the upper limit value of the surface diffused light is updated, it is determined that the surface diffused light is below the upper limit in step S6 when the flow of FIG. It is. By doing this, it is possible to avoid wasting time and costs by outputting the patch image many times in vain.

  In the above-described embodiment, the spectral reflectance is used as the reflection characteristics 1 and 2, but a method using density is also conceivable in order to make the apparatus simpler. In this case, a densitometer is used instead of the spectrocolorimeter 41 as the colorimeter.

  FIG. 4B shows a configuration example of the densitometer. The densitometer includes a light source 61 such as a gas-filled filament lamp, a light receiving element 62 such as a photodiode, an IC (not shown) that processes received light data, and the like. The light source 61 is installed perpendicular to the recording material 11 and irradiates the recording material 11 perpendicularly. The light receiving element 62 is installed in a 45 ° direction with respect to the vertical direction of the recording material 11 and detects reflected light from the recording material 11.

  When calculating the surface diffused light in step S6 of FIG. 5, if the density is used as the reflection characteristics 1 and 2, the surface diffused light is calculated by taking the difference between the two after converting the density into the reflectance. To do. The density conversion formula is given by DR = −log 10 (R), where DR is density and R is reflectance.

  According to the present invention, an image forming unit that forms a patch image having a toner area ratio of 100% and transfers it to a recording material, and a fixing that fixes the patch image transferred to the recording material by the image forming unit under a predetermined fixing condition. Means, surface diffused light acquiring means for obtaining surface diffused light of the patch image fixed by the fixing means, adhesion amount acquiring means for obtaining toner adhesion amount of the patch image, and the acquired surface diffused light and adhesion amount By providing the control means for controlling the predetermined fixing condition based on the above, it becomes possible to control the fixing condition based on the toner adhesion amount and the surface diffused light even when the toner adhesion amount changes.

  According to the present invention, in the surface diffused light acquisition unit, the measuring unit 1 that measures the reflection characteristic 1 of the patch image fixed by the fixing unit, and the transmission layer is formed on the surface of the fixed patch image. Smoothing means for smoothing the surface, measuring means 2 for measuring the reflection characteristic 2 of the patch image smoothed by the smoothing means, and calculating the surface diffused light from the measured reflection characteristics 1 and 2 The surface diffused light can be obtained with high accuracy even when the toner adhesion amount is changed, and the surface diffused light is obtained using the recording paper actually held by the user. be able to.

  According to the present invention, the transparent toner layer is used for the transmissive layer, and the smoothing unit forms a transparent toner image and transfers it to the patch image fixed by the fixing unit. By providing the transparent toner image fixing means for fixing the transparent toner image transferred onto the surface of the patch image by the transparent toner image forming means, the smoothing means can be realized using the transparent toner.

  According to the present invention, after the reflection characteristic 2 measured by the measurement unit 2 is corrected by the transmittance of the transmission layer, the adhesion amount is calculated using the corrected reflection characteristic 2 in the adhesion amount acquisition unit. Thus, the amount of patch image attached can be obtained from the reflection characteristic 2.

  According to the present invention, spectral reflectance is used as the reflection characteristics 1 and 2, and the calculation means corrects the spectral reflectance 2 with the transmittance of the transmission layer, and then takes a difference value between the two to obtain an absorption band. By acquiring the surface diffused light from the value, the surface diffused light can be acquired from the spectral reflectance.

  According to the present invention, density is used as the reflection characteristics 1 and 2, and the calculation means corrects the density 2 with the transmittance of the transmissive layer, converts both into the reflectance, and obtains a difference value between the two. Thus, the surface diffused light can be acquired from the concentration by acquiring the surface diffused light.

  According to the present invention, surface diffused light can be obtained by using the same measurement optical system in the measurement means 1 and 2.

  According to the present invention, by using 0/45 ° in the measurement optical system, surface diffused light that can be directly incorporated into color evaluation can be obtained.

  In the first embodiment, the transparent toner image is further transferred and fixed to the created patch image as the smoothing unit. However, in order to configure the smoothing unit, a developing device for transparent toner in addition to the four colors of CMYK is provided. Newly required, the equipment becomes larger and more complicated. Therefore, in the second embodiment, an embodiment is shown in which smoothing is performed without complicating the apparatus by using colored toner (any of CMY) instead of transparent toner.

  FIG. 9 shows a system configuration of the second embodiment. FIG. 9 is configured by adding a diffuse reflection detection unit 45 to the image forming unit 100 of FIG. 1, and other components are the same as those of FIG. 1.

  FIG. 10 shows the configuration of the image forming unit of the second embodiment. The difference from Example 1 (FIG. 2) is that a photosensitive drum (22W) for transparent toner, an injection charging unit (23W), a writing optical system (24W), a toner cartridge (25W), and a developing unit (26W). This is a point that the diffuse reflection light detection unit 45 is added.

  The measurement principle of the surface diffused light when colored toner is used instead of the transparent toner will be described. Here, as an example, cyan is used for the patch image, and the colored toner image formed thereon is yellow. FIG. 11 shows the spectral reflectance of cyan and yellow. As described above, when calculating the surface diffused light, only the absorption band of the spectral waveform is used. At this time, in the cyan absorption band, yellow is the transmission band from FIG. In other words, when yellow is superimposed on cyan, when viewed only in the cyan absorption band, yellow has the same characteristics as the transmission band, that is, the transparent toner. Therefore, in this case, yellow can be handled in the same manner as the transparent toner, and can be used as a substitute for the transparent toner in the first embodiment. This toner combination may be a combination of magenta and yellow in addition to cyan and yellow. When yellow is used for the patch image, cyan is a candidate for the colored toner. However, even if cyan is in the transmission band, the transmittance is lower than that of yellow. As the transmittance varies greatly, cyan is not suitable as a substitute for transparent toner. However, it is not necessary to control the fixing conditions for all color (CMY) patches, and any one of them may be selected and used. Therefore, even if yellow is used for a patch image, the present invention can be used. There is no hindrance.

  However, in the case of colored toner (yellow toner), the transmittance in the transmission band is higher than that in cyan, but in general, the transmittance in the transmission band is lower than that of the transparent toner of Example 1. As with transparent toners, the amount of adhesion may vary with colored toners, but as described above, the transmittance is low, so when the amount of adhesion varies, the transmission characteristics also vary, affecting the measurement of surface diffused light. Effect. Therefore, in this embodiment, a mechanism for detecting the amount of color toner attached is provided, the transmittance of the color toner is acquired according to the detected amount of adhesion, and the spectral reflectance 2 is corrected using the acquired transmittance. . A specific correction method is the same as that in the first embodiment, and the transmittance of the colored toner (yellow toner) for each adhesion amount is stored in the memory 152 in advance.

  As shown in FIG. 10, in the second embodiment, a diffuse reflection detection unit 45 is installed on the intermediate transfer belt 27 as a mechanism for detecting the amount of colored toner (yellow toner) attached. Although a mechanism for detecting diffused light is provided here, another mechanism for detecting specularly reflected light or a mechanism for detecting both diffused light and specularly reflected light may be used.

  FIG. 4C shows a configuration example of the diffuse reflection light detection unit 45. The diffuse reflected light detection unit includes a light source 71 such as an LED, a light receiving element 72 such as a photodiode, an IC (not shown) that processes received light data, and the like. The light source 71 is installed perpendicular to the intermediate transfer belt 27 and irradiates the intermediate transfer belt perpendicularly. The light receiving element 72 is installed in a 45 ° direction with respect to the vertical direction of the intermediate transfer belt 27 and detects reflected light from the patch image on the intermediate transfer belt.

  FIG. 12 shows the relationship between the color toner (CMY) adhesion amount and the diffuse reflected light output voltage. As shown in the figure, the diffuse reflected light output voltage monotonously increases with the amount of color toner attached. In the image characteristic acquisition unit 150, this relationship is stored in the memory 152 in advance, the diffuse reflection light output voltage is input from the diffuse reflection detection unit 45, and the toner adhesion amount is calculated in the calculation unit 152. As described above, the transmittance of the colored toner layer is obtained by referring to the transmittance of the colored toner for each adhesion amount stored in advance in the memory 152, and the spectral reflectance 2 is corrected based on the result. .

  FIG. 13 is a flowchart of fixing condition control according to the second embodiment. In FIG. 13, the difference from the process of FIG. 5 is that transparent toner is replaced with colored toner and steps S13 and S14 are newly added. In step S13, a color toner image is formed on the intermediate transfer belt, and in step S14, diffused light from the color toner image formed in S13 is detected.

  FIG. 6C shows an example of a patch image according to the second embodiment, and is an example in which cyan is used for the patch. FIG. 6D shows an example of the color toner image of Example 2, and is an example in which yellow is used for the color toner image. The position and shape of the toner image is the same as the cyan patch image in FIG.

  According to the present invention, the color toner layer is used for the transmission layer, the color toner image forming means for forming the color toner image in the smoothing means and transferring the color toner image to the patch image fixed by the fixing means, and the color toner A colored toner image fixing means for fixing the colored toner image transferred to the surface of the patch image by the image forming means and a colored toner adhesion amount acquisition means for acquiring the adhesion amount of the colored toner image are newly provided. Smoothing means can be realized without adding a toner developing device or the like.

  According to the present invention, the color toner image is a toner having a transmission band in the absorption band of the spectral reflection characteristic of the patch image fixed by the fixing unit, and therefore the color toner image is used instead of the transparent toner. The surface diffused light can be acquired.

  According to the present invention, the colored toner adhesion amount acquisition means includes a colored toner image reflection characteristic detection means for detecting at least one of regular reflection light or diffused light of the color toner image formed on the intermediate transfer belt. As a result, it is possible to acquire the adhesion amount of the colored toner image.

  In Examples 1 and 2, smoothing was performed by further forming a transparent or colored toner image on the patch image created on the recording material and providing the thickness of the toner layer. Even if the thickness is provided, it is inevitable that the surface of the transparent or colored toner layer is uneven to some extent as long as the transparent or colored toner is transferred and fixed by a normal transfer / fixing method. Further, when the apparatus deteriorates over time, the fixing of the transparent or colored toner is also affected, so that the surface state changes, and an error may occur in the measurement result of the surface diffused light. Therefore, in this embodiment, an example in which the surface diffused light is measured with higher accuracy by bringing a transparent film having a smooth surface into close contact with the patch image created on the recording material. Show.

  FIG. 14 shows a system configuration of the third embodiment. The difference from Example 1 (FIG. 1) is that a transparent film supply unit 42 is added.

  FIG. 15 shows the configuration of the image forming unit of the third embodiment. The difference from the second embodiment (FIG. 10) is that the diffuse reflection detection unit 45 is removed and a transparent film supply unit 42, a paper feed roller 43, and a registration roller 44 are added.

  The operation of each part when acquiring the surface diffused light will be described with reference to FIG. The patch image created on the photosensitive drum 22 is transferred to the recording material 11 via the transfer belt 27. After the heat fixing by the fixing device 30, the spectral reflectance 1 is measured by the spectral colorimeter 41. Thereafter, the recording material 11 is returned to the front of the fixing device 30 by the reverse rotation of the roller 35. Then, in synchronism with the conveyance of the recording material 11 to the fixing device 30 again, a transparent film loaded on the transparent film supply unit 42 and coated with a colorless and transparent adhesive at a low temperature is supplied to a paper feed roller. The sheet is fed at 43, and is fed by the registration roller 44 to the fixing device 30 at the same time as the recording material 11, and the transparent film is fixed by heating and pressure bonding. Thereafter, the spectral reflectance 2 is measured by the spectral colorimeter 41. Then, the measured spectral reflectances 1 and 2 are input to the calculation unit 152, and surface diffused light is calculated.

  When calculating the surface diffused light in the calculation unit 152, it is necessary to correct the spectral reflectance 2 with the transmittance of the transparent film layer as in the first and second embodiments. A specific method of correction is the same as that in the first embodiment. Therefore, in Example 3, the transmittance of the transparent film layer is stored in the memory 151 in advance, the spectral reflectance 2 is corrected with reference to the value, and the surface diffused light is calculated.

  The transparent film in Example 3 needs to satisfy the following conditions. That is, (1) the surface is a mirror surface or a state close thereto, (2) the refractive index is close to the refractive index of the toner, and (3) the transparency is high.

  The reason for attaching the transparent film is to obtain a mirror surface state, and therefore, (1) is required first. For (2), the light reflected (or diffused) at the boundary depends on the refractive index of the material according to the Fresnel law. When light enters a layer having a different refractive index, light is reflected (or diffused) according to Fresnel law. Therefore, as shown in (2), it is desirable that the refractive index of the transparent film and the toner are close. The refractive index of the toner is 1.5 to 1.6 (depending on the resin). Moreover, about (3), when the transmittance | permeability of a transparent film is low, the light (202 of FIG.18 (b)) light-received in the state which stuck the film from internal reflection light (201b of FIG.18 (a)). Also lower. Therefore, as shown in (3), the transmittance of the transparent film is preferably close to 1.0. In addition, said (2) and (3) are applicable also about the contact bonding layer apply | coated to a transparent film.

  As a transparent film that satisfies the above conditions, a further necessary requirement is a heat-resistant resin film that does not significantly deform due to heating during fixing of the transparent film. Examples of the material include polyethylene terephthalate (PET). PET has a refractive index of 1.57, which is close to that of toner and has high transparency.

  As described above, the transparent film is coated with a colorless and transparent adhesive that melts at a low temperature. A transparent heat-sealable resin is used for this adhesive layer. As described above, this adhesive layer needs to satisfy the conditions (2) and (3) that the transparent film should satisfy. That is, the adhesive layer can be formed by applying a thermoplastic resin as a main component and an additive added as necessary. Examples of the thermoplastic resin that forms the adhesive layer include a polyester resin and a polystyrene resin. In both cases, the refractive index is 1.59 to 1.60, which is close to the refractive index of the toner.

  FIG. 16 is a flowchart of fixing condition control according to the third embodiment. In FIG. 16, what is different from the process of FIG. 5 is step S33, and in step S33, it is replaced with transparent film sticking. Other processes are the same as those in the first embodiment.

  According to the present invention, a transparent film layer is used for the transmission layer, and the smoothing means includes a transparent film sticking means for sticking the transparent film to the patch image fixed by the fixing means. This can be realized with a transparent film.

  According to the present invention, in the transparent film sticking means, the transparent film is brought into close contact with the patch image fixed by the fixing means via an adhesive which becomes transparent or transparent after adhesion stabilization, and is heated or pressurized. By providing a transparent film fixing means for adhering the transparent film to the patch image via the adhesive by at least one of the above, the smoothing means can be realized using a transparent film.

  The present invention supplies a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and a program in which a computer (CPU or MPU) of the system or apparatus is stored in the storage medium. This is also achieved by reading and executing the code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments. As a storage medium for supplying the program code, for example, a hard disk, an optical disk, a magneto-optical disk, a nonvolatile memory card, a ROM, or the like can be used. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on an instruction of the program code. A case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included. Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes the case where the CPU or the like provided in the board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing. Further, the program for realizing the functions and the like of the embodiments of the present invention may be provided from a server by communication via a network.

DESCRIPTION OF SYMBOLS 21 Paper feed part 24 Writing optical system 30 Fixing apparatus 31 Fixing roller 32 Pressure roller 33, 34 Heater 35a, b Thermistor 41 Spectrocolorimeter 110 Fixing condition control part 111 Driver 112 Storage part 120 Main control part 130 Image processing part 140 Operation Display Unit 150 Image Characteristic Acquisition Unit 151 Memory 152 Calculation Unit

JP 2006-171104 A JP 2006-267165 A

Claims (16)

  An image forming unit that forms a patch image with a toner area ratio of 100% and transfers the patch image to a recording material, a fixing unit that fixes the patch image transferred to the recording material under predetermined fixing conditions, and the fixed patch image A surface diffused light obtaining unit for obtaining surface diffused light from the toner, an adhesion amount obtaining unit for obtaining the toner attached amount of the patch image, and controlling the predetermined fixing condition based on the acquired surface diffused light and the toner attached amount And an image forming apparatus.   The surface diffused light acquiring means smoothes the surface by forming a first measuring means for measuring the first reflection characteristic of the fixed patch image and a transmissive layer on the surface of the fixed patch image. A smoothing means; a second measuring means for measuring a second reflection characteristic of the smoothed patch image; and a calculation for calculating surface diffused light from the measured first and second reflection characteristics. The image forming apparatus according to claim 1, further comprising:   The transmission layer is a transparent toner layer, and the smoothing means includes a transparent toner image forming means for transferring the transparent toner image to the fixed patch image, and a transparent toner image transferred to the surface of the patch image. The image forming apparatus according to claim 2, further comprising: a transparent toner image fixing unit that fixes the toner.   The transmission layer is a colored toner layer, and the smoothing means includes a colored toner image forming means for transferring the colored toner image to the fixed patch image, and a colored toner image transferred to the surface of the patch image. The image forming apparatus according to claim 2, further comprising: a colored toner image fixing unit that fixes the color toner; and a colored toner adhesion amount acquisition unit that acquires the adhesion amount of the color toner image.   5. The image forming apparatus according to claim 4, wherein the colored toner image is a toner having a transmission band in an absorption band of a spectral reflection characteristic of the fixed patch image.   The colored toner adhesion amount acquisition means comprises a colored toner image reflection characteristic detection means for detecting at least one of regular reflection light or diffused light of a color toner image formed on an intermediate transfer belt. Item 5. The image forming apparatus according to Item 4.   3. The image forming apparatus according to claim 2, wherein the transmissive layer is a transparent film layer, and the smoothing means includes a transparent film sticking means for sticking a transparent film to the fixed patch image.   The transparent film sticking means attaches the transparent film to the fixed patch image via an adhesive that becomes transparent or transparent after adhesion stabilization, and attaches the adhesive to the transparent film by at least one of heat or pressure. The image forming apparatus according to claim 7, further comprising a transparent film fixing unit that adheres the patch image to the patch image.   The adhesion amount acquisition unit corrects the second reflection characteristic measured by the second measurement unit with the transmittance of the transmission layer, and then calculates the toner adhesion amount using the corrected second reflection characteristic. The image forming apparatus according to claim 1.   The first and second reflection characteristics are spectral reflectances, and the calculation unit corrects the second spectral reflectance with the transmittance of the transmission layer, and then corrects the first spectral reflectance and the corrected first spectral reflectance. 3. The image forming apparatus according to claim 2, wherein a difference value with respect to the spectral reflectance of 2 is taken and surface diffused light is acquired from the value of the absorption band.   The first and second reflection characteristics are densities, and the calculation unit corrects the second density with the transmittance of the transmission layer, and then calculates the first density and the corrected second density as a reflectance. The image forming apparatus according to claim 2, wherein the surface diffused light is acquired by converting into a difference between the two and taking a difference value therebetween.   3. The image forming apparatus according to claim 2, wherein the first and second measuring units are the same measuring optical system.   13. The image forming apparatus according to claim 12, wherein the measurement optical system is an optical system that receives light perpendicularly to the recording material surface and receives light in a direction of 45 ° with respect to a direction perpendicular to the recording material surface.   An image forming step of forming a patch image having a toner area ratio of 100% and transferring it to a recording material, a fixing step of fixing the patch image transferred to the recording material under predetermined fixing conditions, and the fixed patch image A surface diffused light acquiring step for obtaining surface diffused light from the toner, an adhesion amount acquiring step for obtaining a toner attached amount of the patch image, and controlling the predetermined fixing condition based on the acquired surface diffused light and toner attached amount And an image forming method.   A program for causing a computer to realize the image forming method according to claim 14.   15. A computer-readable recording medium on which a program for causing a computer to realize the image forming method according to claim 14 is recorded.

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