JP2019008074A - Glossiness determination device - Google Patents

Abstract

To solve the problem in which: management of glossiness of a product is important for electrophotography; however, an image forming apparatus generally uses a component dedicated to detect glossiness, and the component is not used for purposes other than glossiness detection, and thereby a cost for a result is increased.SOLUTION: An image reading device having a line sensor reading diffused and reflected light mounted thereon and a black image uniformly generated by an image forming apparatus to enable detection of a difference in glossiness in the same plane at a low cost without using a component dedicated to glossiness detection.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gloss determination apparatus associated with an image forming apparatus and a program thereof.

  Conventionally, in an electrophotographic image forming apparatus, when a toner image transferred to a recording material is fixed, reproducing the fixed image as a desired gloss is considered in order to improve the image quality. It has become an important matter.

  In addition, as a fixing device used in an electrophotographic image forming apparatus, a method in which an unfixed toner image on the surface of a recording material is fixed by heating and pressurizing is employed. It is known that the glossiness changes depending on the fixing conditions.

  In view of the above, various configurations have been disclosed in which the glossiness is detected and fed back to the fixing device so as to obtain a desired glossiness.

  Patent Document 1 discloses a fixing unit that fixes a toner image on a recording material to a recording material by nip conveyance between a heating unit and a pressing unit, and a gloss level that detects the gloss level of a fixed image fixed by the fixing unit. Detecting means and heating control means for applying different heating temperatures to the same surface of the recording material to the heating means, wherein the heating control means has an image step whose image gradation gradually changes in the same surface. Glossiness detection using a measurement recording material in which a plurality of sets of toner images having a tonal pattern are formed, and fixing images are formed by fixing the toner images at different heating temperatures for each set of image gradation patterns by the fixing means. The glossiness of the fixed image for each set on the measurement recording material is detected by the means, and the glossiness value of the fixed image for each set detected by the glossiness detection means is calculated as an image gradation and a heating temperature. Associated image gradation pattern Data for each set stored in the storage unit with reference to the image gradation obtained from the pixel data included in the image data so that the fixed image has an arbitrary glossiness. It has been devised that the heating temperature of the heating means is controlled based on gradation pattern data.

JP 2014-219444 A

  However, the gloss detection includes the following problems including the configuration of Patent Document 1. Most of the configurations for detecting the gloss level use a dedicated sensor, and there is no use other than the detection of the gloss level, so that the cost for the result increases. Further, the user feels most uncomfortable regarding the glossiness of the formed image when a difference in glossiness occurs in the same image plane, and it is important to be able to solve this problem.

  The present invention has been made in view of the above problems, and an object thereof is to provide an apparatus capable of detecting a difference in glossiness within the same plane without using a sensor dedicated to glossiness detection.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
An image reading apparatus using a line sensor that can detect image data by irradiating light from a light source to a recording medium on which an image has been formed and receiving diffuse reflection light from the light source, and uniformly black on the recording material In the image forming apparatus capable of forming the image, the black image is read, the luminance difference in the image is detected, and the abnormal portion of the fixing device is specified by the main scanning direction and sub-scanning direction patterns of the luminance difference. Features.

  According to the image forming apparatus of the present invention, it is possible to detect the glossiness within the same surface of the recording medium without increasing the cost by using an apparatus for reading image data.

Image reading apparatus to which the present invention is applied and a longitudinal sectional view of the image reading apparatus Image reading apparatus to which the present invention is applied and a control block diagram of the image reading apparatus Correlation diagram between black image density and glossiness difference in the present invention Flowchart of same-surface gloss difference detection in the present invention Schematic diagram of uniform gloss difference detection for main scanning and sub-scanning in the present invention Schematic diagram of non-uniform gloss difference detection for main scanning and sub-scanning in the present invention

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

  FIG. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus and an image reading apparatus to which the present invention is applied.

  The image forming apparatus 100 according to the present embodiment employs an electrophotographic system, and a sheet feeding unit 110 is disposed below the drawing, and from above the drawing, an exposure unit 120, an imaging unit 130, an intermediate transfer unit 140, a secondary transfer unit, and the like. The transfer unit 150 and the fixing unit 160 are provided in the order of the recording material conveyance process. The recording material P after the toner image is fixed by the fixing unit 160 is accumulated via a paper discharge unit (not shown). In the following description, unless otherwise specified, the recording material P is referred to as upstream and downstream based on the conveyance direction of the recording material P.

  The sheet feeding unit 110 is disposed below the inside of the image forming apparatus 100. The paper feed unit 110 includes a drawer-type paper feed cassette 111. The paper feed cassette 111 can store a recording material P such as a sheet of recording paper. A sheet feeding roller that feeds the recording material P stored in each sheet feeding cassette 110 one by one from the uppermost one and feeds it to the recording material conveyance path 112 is provided at the upper portion on the downstream end side of each sheet feeding cassette 110. 113 is provided. In the paper supply unit 110, a registration unit 114 that adjusts the conveyance timing of the recording material P is disposed between the paper supply roller 113 and the secondary transfer unit 150. Note that the specific configuration and operation of the resist unit 114 are well known, and thus description thereof is omitted. The registration unit 114, the secondary transfer unit 150, the fixing unit 160, and the conveyance roller 115 facing the recording material conveyance path 112 constitute a conveyance unit that nips the recording material P and passes the paper.

  The exposure unit 120 is disposed above the imaging unit 130 and is provided for each color of yellow, cyan, magenta, and black (hereinafter referred to as Y, C, M, and K). For example, the exposure unit 120 irradiates the imaging unit 130 with laser light based on image data transmitted from a personal computer (not shown). Since the specific configuration and operation of the exposure unit 120 are known, description thereof will be omitted.

  Similar to the exposure unit, the imaging unit 130 includes four image forming units for generating toner images for each color of Y, C, M, and K arranged in a quadruple tandem manner. These image forming units use different colors of Y toner, C toner, M toner, and K toner, but the other configurations are common to four colors. Here, the number of colors is not limited, and a configuration having units of five or more colors may be employed. The imaging unit 130 includes a developing device 132 and a charging, discharging, and cleaning device (not shown) around the photosensitive drum 131. Each of these devices is held by a common holding body and is integrally attached to and detached from the device main body so that they can be exchanged at the same time.

  The photosensitive drum 131 has an organic photosensitive layer formed on the surface thereof, and is driven to rotate in the clockwise direction in the drawing by driving means (not shown). The surface of the photosensitive drum 131 that is uniformly charged is optically scanned by a laser beam emitted from an optical writing unit and carries an electrostatic latent image. An optical writing unit serving as a latent image writing unit is disposed above the image pickup unit 130. The photosensitive drum 131 is optically scanned with a laser beam L emitted from a laser diode based on image data, and an image is carried. An electrostatic latent image is formed on the body 132. The developing device 132 makes the toner image visible by attaching charged toner to the electrostatic latent image formed on the surface of the photosensitive drum 131. The developing device 131 has, for example, a developer transport unit that stirs and transports the developer, and a developing unit that houses the developing roller. When the toner image is developed on the photosensitive drum 131 in this manner, the toner image is sequentially transferred to the intermediate transfer belt 141 of the intermediate transfer unit 140 in turn.

  The intermediate transfer unit 140 is an intermediate transfer method in which the toner image formed on the photosensitive drum 131 is transferred to the intermediate transfer belt 141 and then the toner image is transferred from the intermediate transfer belt 141 to the recording material P. The intermediate transfer belt 141 is an intermediate transfer belt on the belt, but the intermediate transfer belt 141 may be drum-shaped. An endless intermediate transfer belt 141 is stretched below the imaging unit 130. In addition to the intermediate transfer belt 141 as an image carrier, the intermediate transfer unit 140 includes a driving roller 142, a secondary transfer back roller 143, four primary transfer rollers 144 corresponding to each color, and the like. The intermediate transfer belt 141 is stretched by a driving roller 142, a secondary transfer back roller 144, and four primary transfer rollers 144 disposed inside the loop. The intermediate transfer belt 141 is rotationally moved in the same direction by the rotational force of the driving roller 142 that is rotationally driven by a driving unit (not shown). The volume resistivity of the intermediate transfer belt 141 is such that the four primary transfer rollers 144 sandwich the rotating intermediate transfer belt 141 between the photosensitive drum 131. As a result, a primary transfer nip for Y, C, M, and K where the surface of the intermediate transfer belt 141 and the photosensitive drum 131 abut is formed.

  A primary transfer bias is applied to the primary transfer roller by a transfer bias power source (not shown). As a result, a transfer electric field is formed between the Y, C, M, and K toner images on the photosensitive drum 131 and the primary transfer roller 144. First, the intermediate transfer belt 141 enters the primary transfer nip portion for Y toner as the photosensitive drum 131 rotates, and the Y toner image is primarily transferred by the action of the transfer electric field and nip pressure. Thereafter, the intermediate transfer belt 41 sequentially passes through the primary transfer nips for C, M, and K. Then, the C, M, and K toner images on the photosensitive drum 131 are primarily transferred onto the intermediate transfer belt 141 while being sequentially superimposed. Next, the toner image primarily transferred to the intermediate transfer belt 141 is secondarily transferred from the intermediate transfer belt 141 to the recording material P in the secondary transfer unit 150.

  The secondary transfer unit 150 includes a secondary transfer roller 151 that faces the secondary transfer back roller 144 with the intermediate transfer belt 141 interposed therebetween. The secondary transfer roller 151 forms a secondary transfer nip portion with the intermediate transfer belt 141, and the recording material P enters the secondary transfer nip portion. While the secondary transfer roller 151 is grounded, a secondary transfer bias is applied to the secondary transfer back roller 144 by a secondary transfer bias power source (not shown). As a result, a secondary transfer electric field for electrostatically moving the negative polarity toner from the secondary transfer back roller 144 side to the secondary transfer roller 151 side between the secondary transfer roller 151 and the secondary transfer back roller 143. Is formed.

  The fixing unit 160 includes a fixing heater 161 as a heating unit, a fixing roller 162 heated by the fixing heater 161, a pressure roller 163 facing the fixing roller element 161, and a temperature sensor 164 that detects the heating temperature of the fixing roller 161. . A pressure roller 163 as a pressure unit forms a fixing nip portion with the fixing roller 162. The pressure roller 163 is opposed to the lower surface of the fixing roller 162 with a predetermined contact pressure by an urging means such as a spring (not shown), and the conveyance direction of the recording material P carrying the toner image T is set. Rotate forward. The recording material P conveyed to the fixing nip is fixed on the toner image T by the heating of the heating element 161 and the pressure of the pressure roller 163 while being conveyed in the nip by the rotational movement of the fixing roller and the pressure roller. .

  In the present embodiment, the image reading device 170 is used to detect a difference in glossiness in the same plane of the recording material P fixed by the fixing unit 160. This image reading apparatus radiates light from a light source 171 to a recording roller P for conveying the recording material P, and detects the diffuse reflected light from the recording material P and converts it into image data. Have As shown in FIG. 1, the image reading apparatus is provided on the discharge port path of the image forming apparatus 100. The inspection apparatus for inspecting the product, the image scanner generally associated with the image forming apparatus, the light source of the object Any device can be used as long as it has a line sensor for detecting diffuse reflected light from the device and can acquire image data.

  FIG. 2 is a block diagram showing a control system of this apparatus.

  In this embodiment, the image forming apparatus is controlled by the image forming apparatus controller 200 and the image reading apparatus is controlled by the image reading apparatus controller 220.

  The image forming apparatus controller 200 mainly plays a role of driving each load of the image forming apparatus, collecting and analyzing information of sensors, and exchanging data with the operation unit 201, that is, the user interface. The internal configuration of the image forming apparatus controller 200 is equipped with the CPU 202 in order to play the above-described role. Run the formation sequence. In addition, RAM 204 is included to store rewritable data that needs to be stored temporarily or permanently. The RAM 204 stores a high voltage set value for the high voltage unit 205, various data, image formation command information from the operation unit 201, and the like.

  In addition to obtaining information such as the copy magnification and density setting value set by the user, the operation unit 201 obtains information on the state of the image forming apparatus, for example, the number of image formations and whether or not an image is being formed, and the location where a jam occurs And data for sending a consumable replacement instruction to the user. In the image forming apparatus 100, one or a plurality of DC loads 206 such as a motor and a clutch / solenoid, and various sensors 207 such as a photo interrupter and a micro switch are arranged at various locations inside the apparatus. By driving the motor and each DC load appropriately by the DC load control unit 208, the recording material is conveyed and each unit is driven, and the operation is monitored by various sensors.

  The image forming apparatus controller 200 operates the DC load 206 by the load control unit 208 based on signals from the various sensors 207 to advance the image forming operation. The high-voltage control unit 209 transmits various high-voltage control signals, and is suitable for various chargers constituting the high-voltage unit 205, which are not shown, such as a primary charger, an auxiliary charger, a transfer charger, and a developing roller in the developer. High pressure is applied. The fixing roller incorporates a fixing heater 161 for heating the roller, and the heater is ON / OFF controlled by an AC driver 210. The fixing roller is provided with a temperature sensor 164 for measuring the temperature, and temperature information of the fixing roller is input to the image forming apparatus controller 200. Based on this temperature information, the above-mentioned AC driver 210 is controlled.

  Similarly to the image forming apparatus controller 200, the image reading apparatus controller 220 also includes a CPU 221, a ROM 222, and a RAM 223, and various DC loads 225 are appropriately driven by a DC load control unit 226 based on signals from various sensors 224. The image reading target is conveyed. In response to the arrival of the image reading target at a predetermined image reading position, the line sensor driver 227 controls the light quantity / lighting of the light source 171 such as an LED to irradiate the image reading target with light, and the line sensor 172 receives the image. The reflected light from the reading object is converted into image data. The CPU performs later-described same-in-plane glossiness difference detection from the image data, transmits the detection result to the image forming apparatus controller 200, and displays an appropriate countermeasure on the operation unit 201.

  FIG. 3 is a schematic diagram of the correlation between the black image density and the in-plane glossiness difference in the present invention.

  FIG. 3A is a test pattern in which the density is changed stepwise. The test pattern with the glossiness changed by the image forming apparatus 100 is printed on two types of recording materials. The recording material is read by the image reading device 170, and the brightness difference [%] and the image density between printed materials having different glossinesses from the obtained image data are graphed in FIG. It can be seen from FIG. 3-2 that the higher the density, the larger the luminance difference [%] due to the difference in glossiness, and the detection accuracy improves. Therefore, a uniform black image is used as a test chart in the same-surface glossiness difference detection in the present invention.

  FIG. 4 is an example of a flowchart for detecting the same in-plane glossiness difference.

  In response to the signal for starting the glossiness difference detection from the operation unit 201, the operation is started. First, the test chart for detection is generated by the image forming apparatus 100 (S401).

  The process of generating the chart has been described with reference to FIG. Next, when the sensor 224 of the image reading device detects that the test chart has reached the reading start position of the image reading device 170 (S402), the line sensor driver 227 is controlled to start acquiring image data of the test chart ( S403).

  The acquired image data is averaged with a predetermined number of pixels in the sub-scanning direction to generate main-scanning image cross-sectional data (S404).

  A difference between adjacent pixels in the main scanning image cross-sectional data is acquired, and it is determined whether the difference exceeds a threshold value (S405). If the difference exceeds the threshold value, it is determined that there is a difference in glossiness in the main scanning direction (S406).

  If it is determined that there is a difference in glossiness, the solution is presented to the operation unit (S407).

  Examples of factors that cause a difference in glossiness in the main scanning direction include damage to the fixing roller and pressure roller, and adhesion of foreign matter. Therefore, replacement or cleaning of the roller is instructed as a solution. If it is determined that there is no difference in glossiness in the main scanning direction, next, sub-scanning direction cross-sectional data is acquired in the same manner as in main scanning (S408), and whether the difference between adjacent pixels in the sub-scanning direction cross-sectional data exceeds a threshold value. A determination is made (S409), and if the threshold value is exceeded, it is determined that there is a difference in glossiness in the sub-scanning direction (S410).

  If it is determined that there is a difference in glossiness, the solution is presented to the operation unit (S411).

  As an example of the cause of the difference in glossiness in the sub-scanning direction, there is a case where the temperature of the fixing roller 162 is low with respect to the basis weight of the paper. When it is determined that there is no difference in glossiness in both main scanning and sub-scanning, the image data is divided into predetermined areas in order to detect random glossiness differences that are not uniform in any direction. The average value of data is acquired (S412).

  It is determined whether the difference between the maximum value and the minimum value of the average image data for each region exceeds a threshold value (S413). If the difference exceeds the threshold value, it is determined that a random gloss difference has occurred (S414). The distribution of the average value of each image data and the pattern recorded in the ROM are compared to perform pattern matching (S415), and a solution corresponding to the pattern is presented (S416).

  As an example of a random gloss difference occurrence factor, if the fixing roller is higher than the paper basis weight, the fixing roller and the paper partially stick together, the attached part is heated for a long time, and the glossiness is other than that Since there is a thing that becomes higher than the portion, if it matches the pattern of the above example, a temperature drop of the fixing roller is instructed as a solution. If it is determined that a random gloss difference does not occur, the glossiness in the same plane as expected is not generated, but it is determined that the image is not a desired image (S417), and the glossiness is adjusted. The method is presented to the operation unit (S418).

  FIG. 5 is a schematic diagram of gloss level difference detection that is uniform in the main scanning and sub-scanning directions in the same in-plane gloss level difference detection flowchart described in FIG.

  FIG. 5A is a test chart in the case where a uniform gloss level difference occurs in the main scanning and sub-scanning directions. The average value of the image data is taken in each of the dotted line frames in the sub-scanning and main-scanning directions to obtain cross-sectional data. FIG. 5B is image cross-sectional data in the main scanning direction. As shown in FIG. 5B, when there is a portion where the difference between adjacent pixels is equal to or greater than the threshold value in the image cross-section data, it is determined that the difference is glossiness, and an optimal solution is presented to the operation unit.

  FIG. 6 is a schematic diagram of random gloss difference detection that is not uniform in the main scanning and sub-scanning directions in the same in-plane gloss difference detection flowchart described with reference to FIG.

  FIG. 6A is a test chart in the case where a uniform gloss level difference occurs in the main scanning and sub-scanning directions. When the image data of the test chart is averaged for each area of the dotted line frame in FIG. 6-2, an image data distribution as shown in FIG. 6-3 is obtained. In FIG. 6C, a region with high brightness is a region with a high image data average value, that is, a region with low glossiness. If the difference between the maximum value and the minimum value of the average value of image data for each region is greater than or equal to the threshold value, it is determined that there is a random gloss difference, pattern matching is performed, and an optimal solution is presented to the operation unit.

100 image forming apparatus, 110 paper feed unit, 111 paper feed cassette,
112 recording material conveyance path, 113 paper feed roller, 114 resist section,
115 transport roller, 120 exposure unit, 130 imaging unit, 131 photosensitive drum,
132 developing device, 140 intermediate transfer unit, 141 intermediate transfer belt,
142 Driving roller, 143 Secondary transfer back roller, 144 Primary transfer roller,
150 secondary transfer section, 151 secondary transfer roller, 160 fixing section,
161 fixing heater, 162 fixing roller, 163 pressure roller,
164 Temperature sensor, 170 Image reader, 171 Light source, 172 Line sensor,
200 Image forming apparatus controller 201 Operation unit
220 image reading device controller, 202 image forming device CPU,
203 Image forming device ROM, 204 Image forming device RAM, 205 High voltage unit,
206 Image forming apparatus various DC loads, 207 Image forming apparatus various sensors,
208 Load control unit, 209 High voltage control unit, 210 AC driver,
220 image reading device controller, 221 image reading device CPU,
222 image reader ROM, 223 image reader RAM,
224 Image reading device various sensors, 225 Image reading device various DC loads,
226 DC load control unit, 227 Line sensor driver

Claims (1)

An image forming apparatus that includes a line sensor that reads an image by irradiating light on a document from a light source and mainly receiving diffuse reflection light from the light source, and can form a black image uniformly on a recording material An image reading device comprising: reading the black image formed by the step, calculating a difference of image data for each predetermined region in the image, and identifying an abnormal portion of the apparatus by analyzing a pattern of the image data. apparatus.