JP4847391B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing a variation in detection precision among a plurality of optical sensors arranged in the image forming apparatus and simultaneously reducing the number of times of cleaning or exchanging reference plates. <P>SOLUTION: In the image forming apparatus which can adjust light emission quantity and a light reception output and has a plurality of detecting means for detecting optical reflectivity, the plurality of detecting means detect the optical reflectivity of a reference plate installed at a facing position of one detecting means in advance, the plurality of detecting means detect the optical reflectivity of the same recording medium when a product is used, whether the detecting means has to be corrected is determined on the basis of a relation between a stored detection result of the reference plate and the detected detection result of the recording medium, and when the detecting means is determined to have to be corrected, the detecting means with the reference plate arranged detects the optical reflectivity of the reference plate, and a detecting means that should correct the light emission quantity and the light reception output is specified on the basis of the stored detection result of the reference plate and the detected detection result of the reference plate. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to an image forming equipment, that is, relates to an image forming equipment for forming an image on a recording material (transfer material, printing paper, photosensitive paper, electrostatic recording paper or the like, the following media).

  In recent years, color image forming apparatuses employing an electrophotographic method or an ink jet method such as a color printer or a color copying machine are required to have high output image quality and high stability. In particular, important factors that determine quality include density gradation and stability, and whether or not the color desired by the user can be reproduced correctly.

  However, the density and chromaticity of the output image vary depending on factors such as changes in the usage environment of the image forming apparatus, fluctuation factors of each part of the apparatus due to long-term use, and the type of recording medium used. In particular, in the case of an electrophotographic color image forming apparatus, even a slight environmental change or a difference in recording medium may cause a change in transferability, fixability, and finally density and chromaticity, thereby losing color balance. . Under such circumstances, there is a method for monitoring the state of the image forming apparatus by attaching a plurality of sensors to the image forming apparatus as means for improving the image quality and stabilizing the image forming apparatus.

  For example, an environmental sensor that detects the temperature and humidity of the outside air detects the temperature and humidity where the image forming apparatus is placed, and determines fan control and transfer target bias suitable for the environment. For example, the media sensor identifies the type of the recording material based on the result of detecting the reflectance of the recording material, and the user automatically selects the optimum fixing condition without specifying the type of the recording material (Patent Literature). 1).

  Further, the type of the recording agent is specified, and the optimum transfer condition is selected in addition to the fixing condition. The color sensor is installed in the recording medium conveyance path after fixing, and automatically detects the reflectance of the recording material and the color patch on the recording material, and based on the result, the density gradation characteristic is changed to a desired form ( Patent Document 2).

  Among them, most of the media sensors and color sensors are optical sensors that are disposed in the recording conveyance path and include a light emitting unit and a light receiving unit.

  In general, these optical sensors can be used more effectively when it is possible to detect a reference object having high durability and small manufacturing variation. Specifically, if the detection result of the measurement object with respect to the detection result of the reference plate is related to a physical quantity to be measured in advance, accurate measurement can be performed. Further, the change with time of the sensor can be calibrated by storing the reference plate detection result in advance and comparing it with the result of detecting the reference plate again at an arbitrary timing.

For example, with the color sensor described above, absolute chromaticity can be measured with high accuracy, and image conversion that has conventionally had to be calibrated using an external measuring device other than an image forming apparatus such as a spectrophotometer. The table can be automatically corrected. Also, in the case of an image scanner that detects the color and position information of a document to be copied in a copying machine, the background color is removed or the color of the copied document is accurately reproduced when the document to be copied is colored. Is possible. Therefore, in an image forming apparatus that requires high image quality and high stability, a plurality of sensors for monitoring the state of the image forming apparatus are arranged in the apparatus. It was necessary to arrange on the opposite surface.
JP 2002-182518 A JP 2003-084532 A

  However, the conventional image forming apparatus described above has the following problems. Conventionally, in such an image forming apparatus having an optical sensor having a plurality of reference plates, each optical sensor always uses the reference plate detection result of each opposing surface as a reference, and compares it with the output value of the measurement object. Physical quantity was measured. In practice, however, the total number of image forming apparatuses used and the amount of toner consumed change with time due to the reference plates themselves of each sensor becoming dirty or damaged. The degree of change over time of the reference plate differs depending on the arrangement position of each optical sensor. However, since each optical sensor always uses the reference plate detection result of each opposing surface as a reference, variations in detection accuracy occur between the optical sensors. As a result, optimal image formation may not be performed. Next, a specific example will be described.

  For example, a case will be described in which an image forming apparatus having a media sensor and a color sensor each provided with a reference plate on the opposing surface has a large change with time with respect to the reference plate of the color sensor. In this case, although the detection accuracy of the color sensor is good, the detection accuracy of the media sensor is lowered. As a result, the density gradation characteristics can be maintained in a desired state, but the fixing conditions may not be optimal. Then, the printing speed is reduced, the productivity is lowered, and further, since it is different from the optimum fixing conditions, the gloss obtained under the predetermined image forming conditions may not be obtained. Moreover, even if each optical sensor stores in advance the output at the time of detecting the reference plate and can detect the deterioration of the reference plate itself, it is necessary to clean and replace all the reference plates. . In such a case, there is a problem that the downtime of the printer is increased or the number of replacement parts is increased.

  The present invention has been made to solve the above problems, and in an image forming apparatus having an optical sensor provided with a reference plate, each sensor detection of a common recording medium based on a detection result of a certain reference plate. The characteristics of each sensor are corrected using the result. Accordingly, it is possible to provide an image forming apparatus capable of reducing variations in detection accuracy among a plurality of optical sensors arranged in the image forming apparatus and at the same time reducing the number of cleaning or replacement of the reference plate.

In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus having a plurality of detecting units that can adjust a light emission amount or a light receiving output and detect an optical reflectance , and one of the plurality of detecting units. disposed on opposite surfaces of the detecting means, for storing light emitting amount or the reference plate for correcting the light output, the detection result of the optical reflectivity of advance the reference plate detected by the plurality of detecting means of the detection means Storage means and a recording medium detection control means for controlling the optical reflectance of the same recording medium to be detected by the plurality of detection means, and stored in the storage means by the detection means provided with the reference plate The relationship between the detected detection result of the reference plate and the detected detection result of the recording medium, the detection result of the reference plate stored in the storage means by the detection means where the reference plate is not installed, and the detection The detection means in which the reference plate is arranged when the first value representing the difference does not fall within the range defined by the predetermined first threshold value by comparing the relationship with the detection result of the recorded recording medium. Detection control means for controlling to detect the optical reflectivity of the reference plate, and the detection result of the reference plate stored in the storage means by the detection means provided with the reference plate and the detection result of the detected reference plate If the second value representing the difference does not fall within the range determined by the predetermined second threshold value, the detection means on which the reference plate is installed should correct the light emission amount or the light reception output. When the second value representing the difference is within a range determined by a predetermined second threshold value, the detection means in which the reference plate is not installed is corrected for the light emission amount or the light reception output. specifying means for specifying and should detecting means , And having a correction means for correcting the amount of light emission or light reception output of the identified sensing means by the specifying means.

In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus having a plurality of detecting means that can adjust a light emission amount or a light receiving output and detect an optical reflectance. A reference plate installed on the opposing surface of one detection means for correcting the light emission amount or light reception output of the detection means, and a detection result obtained by detecting the optical reflectance of the reference plate in advance by the plurality of detection means; The optical reflectance of the same recording medium is detected by the storage means for storing the detection result obtained by detecting the optical reflectance of the reference storage medium in advance by the detection means for which the reference plate is set, and the plurality of detection means. a detection control means for the recording medium to be controlled, the relationship between the detection result of the detection result and the detected recording medium of the reference plate stored in the storage means by the detecting means the reference plate is installed A first value representing a difference between the detection result of the reference plate stored in the storage means by the detection means in which the reference plate is not installed and the detected detection result of the recording medium is compared. Of the reference recording medium stored in the storage means by the detection means provided with the reference plate and the detection result of the detected reference recording medium is not within the range defined by the first threshold value determined in advance. When the third value representing the difference is within a range determined by a predetermined third threshold, the optical reflectance of the reference plate is detected by the detecting means on which the reference plate is arranged. and detection control means for controlling so as to, when the third value representing the difference does not fit between prescribed by the third threshold value determined in advance, the light emission amount or receiving outputs a detection means for the reference plate is installed Detection means to be corrected When the third value representing the difference falls within a range determined by a predetermined third threshold value, the detection result of the reference plate stored in the storage means by the detection means provided with the reference plate and Compared with the detected detection result of the reference plate, if the second value representing the difference does not fall within the range defined by the predetermined second threshold, it is identified as a contamination of the reference plate, If the second value representing the difference falls within the range established by the second threshold determined in advance, a detection means for the reference plate is not installed emission amount or specifying means for specifying a detection means to be corrected received light output And a correcting means for correcting the light emission amount or light reception output of the detecting means specified by the specifying means .

The plurality of detection means for detecting the optical reflectance includes an image scanner that reads an image from a document. Further, the plurality of detection means for detecting the optical reflectance includes detection means arranged in the conveyance path of the recording medium. Wherein arranged detecting means in the conveying path of the recording medium includes at least one of a color sensor for detecting the optical reflectance is formed on the media sensor and the recording medium to detect the optical reflectivity of the recording medium image.

  According to the present invention, in an image forming apparatus having an optical sensor provided with a reference plate, the characteristics of each sensor are obtained using the detection results of one common reference plate and using the detection results of each sensor on a common recording medium. Correct. As a result, it is possible to provide an image forming apparatus capable of reducing variations in detection accuracy among a plurality of optical sensors arranged in the image forming apparatus and at the same time reducing the number of cleaning or replacement of the reference plate. Become.

  In addition, by sharing the reference plate with a plurality of optical sensors, it is possible to save space and reduce the cost of the apparatus, while preventing durability deterioration and increasing the degree of freedom of the arrangement position of the optical sensor with high detection accuracy. Therefore, it is possible to provide an image forming apparatus with low load, high image quality, and high stability to the user.

  Further, in an image forming apparatus that has a plurality of optical sensors and the reference plate is provided only in any one of the optical sensors, all of the optical sensors that can detect the output of the recording medium are formed with one reference plate. It is possible to provide a method capable of calibrating the optical sensor.

  The best mode for carrying out the invention will be described below in detail with reference to the drawings. In the first embodiment, an electrophotographic full-color digital copying machine will be described as an example of a color image forming apparatus. However, the present invention is not limited to this, and may be applied to, for example, a color laser beam printer or an inkjet printer. It can be applied.

[Embodiment 1]
Embodiment 1 shows a configuration in which an image scanner for reading an original provided with a reference plate on an opposing surface and a media sensor not provided with a reference plate are provided in the image forming apparatus. With such a configuration, the detection accuracy variation of both sensors is reduced, and even if the media sensor does not have a reference plate, the sensor output result of the same recording material is used to identify the sensor to be calibrated, and the sensor to be calibrated is calibrated. A method that can be performed will be described.

<Example of Configuration of Image Forming Apparatus of Present Embodiment>
FIG. 3 is a schematic cross-sectional view showing an example of the overall configuration of an electrophotographic image forming apparatus showing an embodiment of the image forming apparatus.

  The electrophotographic image forming apparatus shown in FIG. 2 is a 4-drum full-color digital copying machine. A full color image of a document placed on the document table 10 is read by an image scanner (not shown), and an image signal is transmitted to an image data input unit (not shown). Reference numerals 50Y, 50M, 50C, and 50K denote photosensitive drums, which are provided in image forming stations provided with developing materials (toners) of yellow, magenta, cyan, and black, respectively. On the surface of each photosensitive drum 50Y, 50M, 50C, 50K based on the image data sent from the image data input unit (not shown) from the laser scanner device 51Y, 51M, 51C, 51K corresponding to each color. Laser exposure is performed to form a latent image. On the surface of each of the photosensitive drums 50Y, 50M, 50C, and 50K on which the latent image is formed, a toner image is formed by developing with yellow, magenta, cyan, and black developers, respectively.

  An intermediate transfer belt 40 is stretched by a driving roller 41, a tension roller 42, and a driven roller 43. On the intermediate transfer belt 40, the toner images of the respective colors formed by the photosensitive drums 50Y, 50M, 50C, and 50K are primarily transferred.

  Reference numeral 80 denotes a paper feed cassette on which a recording material P that is a recording medium is loaded. The recording material P is fed by a paper feed roller 31, transported by a feed / retard roller pair 32 and a transport roller pair 33, and transported to a resist roller pair 34 whose driving is stopped. At this time, the recording material P is temporarily stopped by the registration roller pair 34, and the media sensor 71 measures the optical reflectance at a predetermined position of the recording material, and based on the result, image formation after the secondary transfer described later is performed. Determine the conditions. Then, after the skew of the recording material P is corrected by the registration roller pair 34, the recording material P is conveyed to the secondary transfer unit 60 at a predetermined timing, and the toner image on the intermediate transfer belt 40 is transferred. The toner remaining on the intermediate transfer belt 40 in the secondary transfer is removed by the cleaning unit 44.

  The recording material P is conveyed to the fixing device 61 by the secondary transfer roller 60 a of the secondary transfer unit 60 and the intermediate transfer belt 40. In the fixing device 61, the toner image is fixed by being held between the fixing roller 62 and the pressure roller 63. The recording material P that has passed through the fixing device 61 is conveyed to a fixing paper discharge roller pair 64 and a paper discharge roller pair 65 and is discharged and stacked on a paper discharge tray 66.

(Image scanner configuration example)
FIG. 4 is a diagram showing a configuration example of the image scanner 12a installed in the document table 10 for reading full color image data input to an image data input unit (not shown in FIG. 3).

  An illumination means 12b such as an LED irradiates the surface of the document O through the document table glass 12d, and is imaged by the line sensor 12c, which is composed of a CMOS or CCD. A halogen lamp 12b is used as the light emitting element, and a charge storage type sensor 12c with an on-chip filter of three or more colors such as RGB is used as the light receiving element. The halogen lamp 12b is disposed on the front side of the main body, and is adjusted to emit light with a uniform light amount with respect to the document by a light guide (not shown) toward the back side of the main body. The white LED 12b is incident on the document O at an angle of 45 degrees, and the intensity of diffusely reflected light in the 0 degree direction is detected by the charge storage sensor 12c with an RGB on-chip filter.

  The image scanner 12a includes a reference plate 13 at the left end of the document table 11, and includes a reference plate 13 on the opposite surface for correcting a change with time due to durability and voltage fluctuation. Then, the output of the reference plate 13 is monitored at a fixed timing and compared with a reference output value stored in a storage area (not shown) of the image forming apparatus. When the amount of change is larger than a certain amount of change, the light emission amount at the time of measurement or the gain for each pixel can be varied so that the same output as the reference output value can be obtained again. If the recording material P is placed on the document table 11, the reflectance of the recording material itself can be measured.

(Configuration example of media sensor)
FIG. 5 is a diagram illustrating a configuration example of the media sensor 71 located upstream of the registration roller pair 34 in FIG. 3.

  The recording material surface P is irradiated by an illuminating means 72 such as an LED, and an image is picked up by an area sensor 73 composed of a CMOS or CCD. Since light is incident obliquely on the surface of the recording material, a shadow is formed according to the irregularities on the surface of the recording medium. This is detected by the area sensor 73, and the paper type such as plain paper, rough paper, and coated paper can be discriminated based on the depth of the unevenness and the fineness of the unevenness. Here, the depth of the unevenness can be determined by, for example, the difference between the maximum value and the minimum value of the output of the plurality of pixels, and the fineness of the unevenness is determined by, for example, the switching frequency between 1 and 0 when the sensor output is binarized. it can.

  As described above, in the image forming apparatus according to the first embodiment, two optical sensors capable of measuring the optical reflectance of the recording material P are arranged in the main body. A sensor calibration reference plate is arranged only on the opposite side of the image scanner 12a. In such a configuration, hereinafter, even if the media sensor 71 has no reference plate, the sensor output of the same recording material P is used to identify the sensor to be calibrated and calibrate the sensor to be calibrated. A possible specific method will be described.

<Configuration Example of Control Unit of Image Forming Apparatus of Present Embodiment>
FIG. 1A is a block diagram illustrating a configuration example of a control unit of the image forming apparatus according to the present exemplary embodiment. The control unit controls the operation of the image forming apparatus of the present embodiment. In FIG. 1A, the part related to the check and correction of the optical sensor of the present embodiment is shown, and other parts related to control are omitted.

  In FIG. 1A, reference numeral 21 denotes a CPU for arithmetic control, which controls by loading a program stored in the external storage unit 24 into the RAM 23 and executing it. Reference numeral 22 denotes a ROM which stores a fixed program and fixed parameters at startup.

  Reference numeral 23 denotes a RAM, which is used as a work memory for primary storage of data for which the CPU 21 is executing a program. In the RAM 23, the following areas are secured in the RAM 23.

  A flag 23a indicates whether the image forming apparatus is an operation before assembly or an operation when the product is used. As will be described later, different programs are executed before assembly and when the product is used. Reference numerals 23b to 23k denote areas for storing parameters necessary for checking and correcting the optical sensor according to the present embodiment. The parameters stored in such an area are shown in a table in FIG. 1B (Embodiment 1) and FIG. 6 (Embodiment 2). The following description will be given in the case of the first embodiment.

  Oint (S1 / S3) 23b is a light reception output of the reference plate by the image scanner before assembly, and is data stored in the external storage unit 24. Oint (S2 / S4) 23c is a light reception output of the reference plate by the media sensor before assembly, and is data stored in the external storage unit 24. Pint (S1 / S3) 23d is a light amount when the reference plate is measured by the image scanner before assembly, and is data stored in the external storage unit 24. Pint (S2 / S4) 23e is a light amount when the reference plate is measured by the media sensor before assembly, and is data stored in the external storage unit 24. Om_int (S3) 23f is a light reception output of the reference recording material Q by the media sensor having the reference plate before assembly in the second embodiment, and is data stored in the external storage unit 24.

  Occur (S1 / S3) 23g is a light reception output of the recording medium by the image scanner when the optical sensor is checked when the product is used. Om_cur (S1 / S3) 23h is a light reception output of the recording medium P by the image scanner when the optical sensor is checked when the product is used. Om_cur (S2 / S4) 23i is a light reception output of the same recording medium P by the media sensor when the optical sensor is checked when the product is used. Pcur (S1 / S3) 23j is a light amount when the storage medium P is measured by the image scanner when the optical sensor is checked when the product is used. Pcur (S2 / S4) 23k is the light quantity when the storage medium P is measured by the media sensor when the optical sensor is checked when the product is used.

  23m is a threshold value (x1, x2) that defines the range of the output ratio of both sensors in the program branch. 23n is a threshold value (y1, y2) that determines the range of the output ratio of the image scanner in the program branch in the first embodiment. 23p is a threshold value (z1, z2) that determines the range of the output ratio of the media sensor in the program branch in the second embodiment. . 23q is a threshold value (a1, a2) that determines the range of the output ratio of the media sensor in the program branch in the second embodiment.

  Pint ′ (S1 / S3) 23r is a corrected light amount at the time of measuring the reference plate when the light amount of the image scanner is corrected, and Pint (S1 / S3) 24c of the external storage unit 24 is used for the subsequent processing. Updated. Pint '(S2 / S4) 23s is a corrected light amount at the time of measuring the reference plate when the light amount of the media sensor is corrected, and Pint (S2 / S4) 24d of the external storage unit 24 is used for subsequent processing. Updated.

  Reference numeral 23 t denotes a program load area in which a program stored in the external storage unit 24 is loaded for execution by the CPU 21.

  Reference numeral 24 denotes an external storage unit such as a disk or a CD, which is used to store programs executed by the CPU 21 and parameters held in a nonvolatile manner. The external storage unit 24 stores the following programs and parameters in the present embodiment.

  Reference numerals 24a to 23e denote areas for storing parameters necessary for checking and correcting the optical sensor of the present embodiment. Here, data detected before assembly, light amount repeatedly used, and the like are held. Since the contents are also described in the RAM 23, they are omitted here. 24f stores a fixed value t (see FIG. 1B and FIG. 6) for converting the light amount Pint at the time of measuring the reference plate into the light amount Pcur at the time of recording medium measurement.

  Reference numerals 24g to 24j are thresholds which are program branching conditions, and are the same as 23m to 23q of the RAM 23.

  An image formation control program 24k controls the entire image formation by the image forming apparatus. Reference numeral 24m denotes a measurement program before assembly, which corresponds to the flowchart on the left side of FIG. 2 in the first embodiment and the flowchart on the left side of FIG. 7 in the second embodiment. Reference numeral 24n denotes a configuration program when the product is used, which corresponds to the flowchart on the right side of FIG. 2 in the first embodiment and the flowchart on the right side of FIG. 7 in the second embodiment.

  An input interface 25 interfaces external signal and data inputs. In this embodiment, the input interface 25 is connected to the light receiving unit 12c of the image scanner, the light receiving unit 73 of the media sensor, the light receiving unit 103a of the color sensor, and an operation unit 25c such as a keyboard or a touch panel.

  An input interface 25 interfaces external signal and data inputs. In this embodiment, the input interface 25 is connected to the light receiving unit 12c of the image scanner, the light receiving unit 73 of the media sensor, the light receiving unit 103a of the color sensor, and an operation unit 25c such as a keyboard or a touch panel.

  Reference numeral 26 denotes an output interface for interfacing the output of signals and data to the outside. In this embodiment, the output interface 26 is connected to a light emitting unit 12b of an image scanner, a light emitting unit 72 of a media sensor, a light emitting unit 102 of a color sensor, a display unit 26a such as an LED, and a printer engine 27 for forming an image. .

(Variables used in the control unit)
FIG. 1B is a diagram illustrating a variable list used in the description of the first embodiment and a table describing the description. However, in the table, the image scanner 12a with the reference plate is represented by S1, and the media sensor 71 without the reference plate is represented by S2.

<Operation Example of Image Forming Apparatus of this Embodiment>
FIG. 2 is a flowchart showing an example of the procedure of the optical sensor adjustment method in the image forming apparatus according to the first embodiment, and will be described in order according to each step. The adjustment step of the first embodiment is roughly divided into two before the assembly of the image forming apparatus and when the product is used.

(Example procedure before assembly)
First, each step before the assembly of the image forming apparatus will be described.

  In step S11, the reference plate 13 disposed opposite to the image scanner 12a is measured using a pair of image scanners 12a and media sensors 71 disposed in the image forming apparatus. At this time, the power source for driving each sensor and the electrical circuit of the measurement system preferably have the same configuration as when each sensor is arranged in the image forming apparatus. However, if the correlation representing the measurement condition difference and the measurement configuration difference after both sensors are incorporated in this step and the image forming apparatus is known in advance, it can be corrected even when the product is used. .

  In step S12, each sensor reference plate output (Oint (S1), Oint (S2)) and reference plate measurement conditions (Pint (S1), Pint (S2)) in step S11 are stored in each sensor not shown. It memorize | stores in the area | region or the memory area of a control part. After the above steps S11 and S12 are performed, the image forming apparatus is assembled into a product.

(Example of detection control procedure when using the product)
Thereafter, in the environment where the product is used, in step S13, the same recording material P is measured by each sensor. Here, it supplements regarding the timing to measure, and a measuring method. In the configuration of the image forming apparatus according to the first embodiment, the media sensor 71 can automatically measure the reflectance of the recording material P for each page. However, with respect to the image scanner 12a, the recording material P output from the arrangement position is used. It cannot be detected automatically. Therefore, in the first exemplary embodiment, after a predetermined time has elapsed since the previous adjustment, the user is notified to make an adjustment via the control portion of the image forming apparatus. As the notification means, for example, the information is output to the screen of the client or the host PC via an operation panel of the image forming apparatus or a driver. Or an e-mail etc. are mention | raise | lifted. Regarding the measurement method, in the first embodiment, the media sensor 71 has a special measurement mode in which the fed recording material P is temporarily stopped to obtain a sensor output value so that the detection accuracy of each sensor is maximized. However, the present invention is not limited to the case of the present embodiment. For example, the average value of the detection results of a plurality of points may be used as the output of each sensor for the same recording material P being conveyed.

  Next, in step S14, the output result (Om_cur (S1) and Om_cur (S2)) of the same recording material P, which is the measurement result of step S13, is used as the reference plate output result (Oini (S1)) of each sensor before assembly. Compare with Oini (S2)). However, the sensor light quantity when measuring the same recording material P is Pcur (S1) and Pcur (S2), respectively, and the light quantity Pint (S1) and Pint (S2) when measuring the reference plate before assembly is t (fixed value). It shall be multiplied. Specifically, as in the following (Equation 1), each sensor output ratio of the same recording material P falls within a certain range with respect to each sensor output ratio when the reference plate before assembly is measured. Determine whether or not. Here, the lower limit threshold is represented by x1, and the upper limit threshold is represented by x2.

x1 <{(0m_cur (S2) / Om_cur (S1)) / (Oini (S2) / Oini (S1))} <x2 (Formula 1)
In the first embodiment, x1 = 0.9 and x2 = 1.1. In this step, that is, it is determined whether or not the relationship between the output ratios of the sensors that have detected the same reference plate before product assembly is maintained at any timing during product use. In addition, the output ratio of each sensor is calculated using the same recording material P instead of the reference plate. Here, the calculated value (which may be a ratio or a difference) is referred to as a first value representing a difference, and a threshold value that defines a range is referred to as a first threshold value.

  Therefore, in step S14, if the condition of (Expression 1) is satisfied, it can be considered that each sensor maintains the state before assembly. In this case, the sensor 2 (corresponding to the media sensor 71 in the present embodiment) in which the reference plate is not disposed oppositely is the same as the case where the reference plate is present based on the value stored in step S12. It can be measured with high accuracy.

  On the other hand, when (Expression 1) cannot be satisfied, that is, when it is determined that the state has changed from the state before assembly, it is determined which of the image scanner 12a and the media sensor 71 has changed, and the target sensor is determined. It is necessary to calibrate. Therefore, in step S15, the reference plate is measured again by the image scanner 12a provided with the reference plate. In step S16, it is determined whether the ratio with the previous (initial) reference plate output is greater than or equal to a threshold value. Specifically, as in (Expression 2), it is determined whether or not the output ratio of the image scanner 12a (sensor 1) of the reference plate before assembly and the present is within a certain range. Here, the lower threshold is represented by y1, and the upper threshold is represented by y2. However, at this time, the light emission amount used for the reference plate measurement by the image scanner 12a is the same as Pint (S1) before assembly.

y1 <Ocur (S1) / Oini (S1) <y2 (Formula 2)
In the first embodiment, y1 = 0.95 and y2 = 1.05, which are smaller than the allowable range | x1-x2 | in step S14. The reason for this is that in (Equation 2), only the detection reproducibility error of the image scanner 12a (sensor 1) and the allowable change need be considered. On the other hand, in (Expression 1), in addition to the detection reproducibility error and the allowable change amount of each of the image scanner 12a (sensor 1) and the media sensor 71 (sensor 2), the detection position error of the recording material P is also considered. It is necessary. Here, the calculated value (which may be a ratio or a difference) is referred to as a second value representing a difference, and a threshold value that defines a range is referred to as a second threshold value.

  In this step, that is, it is determined whether or not the absolute value of the output of the image scanner 12a (sensor 1) that has detected the same reference plate as that before product assembly is maintained at an arbitrary timing during product use.

  Therefore, if the condition of (Equation 2) cannot be satisfied in step S16, it can be determined that the image scanner 12a (sensor 1) has changed over time. Therefore, in step S17, the image scanner 12a which is a sensor provided with a reference plate is calibrated.

  As a specific calibration method, in the present embodiment, a method of changing the light emission amount of the sensor is adopted. In other words, Pini ′ (S1) is calculated as in the following (Equation 3), and Pint (S1) = Pini ′ (S1) is calculated in step S18, and the pre-assembly standard stored in the memory (not shown) in step S12. The light quantity Pint (S1) at the time of plate measurement is updated.

Pini '(S1) = Pini (S1) x Oini (S1) / Occur (S1) (Formula 3)
As a result, the amount of light Pcur (S1) at the time of measuring the recording medium P is also changed simultaneously from the relationship of t times Pint (S1) (t is fixed). Then, when the reference plate is measured again by the image scanner 12a (sensor 1) from the next measurement, the same value as that before assembly is output.

  On the other hand, if the condition of (Equation 2) is satisfied in step S16, the image scanner 12a (sensor 1) can be regarded as being in the same state as before assembly, and the media sensor 71 (sensor 2) changes with time. Can be specified. Then, similarly to step S17 and step S18, the light quantity of the media sensor 71 is changed in the future, and the media sensor 71 is calibrated.

  Specifically, Pcur ′ (S2) is calculated as in the following (Equation 4), and in step S20, Pcur (S2) = Pcur ′ (S2) is set, and the next recording medium P is stored in the memory (not shown). Stored as the light intensity Pcur (S2) at the time of measurement.

Pcur '(S2) = t × Pini (S2) × Om_cur (S1) / Om_cur (S2) (Formula 4)
Then, from the next measurement, the output of the recording material P measured again by the media sensor 71 (sensor 2) has a substantially constant ratio with the output of the same recording medium P measured by the image scanner 12a (sensor 1). .

  In this embodiment, a method of correcting the amount of light at the time of measurement is used for the sensor to be calibrated. However, for example, the gain on the light receiving side of each sensor may be used. Further, in this embodiment, the output fluctuation between each sensor before assembly and when the product is used is obtained using a ratio, but a difference value may be used.

In short, paper as a common detection medium,
・ Difference between reference plate outputs before assembly (ratio)
・ Difference in paper output when using the product (ratio)
・ Difference between output of reference plate during assembly and product use (ratio)
The range in which the sensor to be calibrated is discriminated using and the target sensor is calibrated is included in the invention.

  As described above, in the configuration in which two optical sensors are arranged in the image forming apparatus and the reference plate is arranged only on one sensor facing surface, the sensor to be calibrated by using the sensor output of the same recording material to be passed And a method that can calibrate the sensor has been described. Further, an image forming apparatus capable of adjusting the present invention has been described. Thereby, in the image forming apparatus in which a plurality of optical sensors are arranged, only one optical sensor is provided with the reference plate. For this reason, it is possible to provide an image forming apparatus having high image quality and high stability by realizing high-accuracy detection with all the optical sensors at the same time while realizing space saving and low cost.

[Embodiment 2]
Hereinafter, Embodiment 2 of the present invention will be described in detail with reference to the drawings. In the second embodiment, a full-color LBP is described as an example of a color image forming apparatus. However, the present invention is not limited to this, and can be applied to, for example, a full-color digital copying machine or an inkjet printer.

  In the first embodiment, the optimum calibration method has been described in the case where the surface of the reference plate is placed in a place where it is not soiled due to the arrangement configuration. However, in consideration of all cases in actual use, the reference plate itself is not completely free from the possibility of contamination. Further, from the viewpoint of the hardware configuration and usability of the image forming apparatus, the reference plate may be inevitably disposed at a place where the image forming apparatus may be dirty. Therefore, in the second embodiment, the sensor output result of the reference recording material P is stored in advance by the media sensor 71 having the reference plate before assembly. A method and an image forming apparatus capable of automatically determining whether the reference plate itself is dirty, whether the sensor should be calibrated, and which sensor is the calibration target will be described.

<Example of Configuration of Image Forming Apparatus of Present Embodiment>
FIG. 8 is a schematic cross-sectional view showing an example of the overall configuration of an electrophotographic image forming apparatus showing an embodiment of the image forming apparatus.

The electrophotographic image forming apparatus shown in FIG. 8 is a four-drum full-color laser beam printer. The following three points are different from the full-color digital copying machine of FIG. 2 described in the first embodiment.
-No document table 10-A reference plate is arranged opposite to the media sensor 71-A color sensor 100 and an opposite plate are arranged in the double-sided conveyance path In the following description, the first embodiment other than the above three points is described. Description of common elements is omitted. However, the double-sided conveyance path here refers to a general term for paths from the conveyance roller pair 65 to the conveyance roller pairs 90, 91, 92 and the registration roller pair 34.

  The recording material P is transported to the pair of transport rollers 90, 91, 92 when the double-sided printing command is issued from the image controller (not shown), is transported to the pair of transport rollers 90, 91, 92, and stops driving again. It is conveyed to the registration roller pair 34.

(Configuration example of media sensor)
Next, the media sensor 71 of the present embodiment will be described with reference to FIG. The difference from the media sensor 71 of the first embodiment described with reference to FIG. 5 is that a reference plate 70 for correcting a change with time due to durability and voltage fluctuation is provided on the opposing surface.

  In this media sensor, the output from the reference plate 70 is monitored at a fixed timing and compared with the reference output value stored in the storage area of the image forming apparatus. When the amount of change is larger than a certain amount of change, the light emission amount or gain at the time of measurement is variable so that the same output as the reference output value can be obtained again.

  As can be seen from FIG. 9, the media sensor 71 is located below the secondary transfer unit. If a paper jam occurs in the secondary transfer unit, depending on the method of processing the recording material P remaining in the machine, There may be a case where unfixed toner on the belt or the recording material P is scattered. However, on the other hand, even if the reference plate 70 becomes dirty, from the viewpoint of usability, the media sensor 71 of the present embodiment is easier to clean than the color sensor 100 arranged in the double-sided conveyance path. A reference plate is arranged oppositely.

(Color sensor configuration example)
Next, the color sensor 100 will be described. The color sensor is disposed between the conveyance roller pair 91 and 92 in the double-sided conveyance path downstream from the fixing device 61 in the recording medium conveyance path, and is a single color or mixed color patch after fixing formed on the recording material P. Are detected while being conveyed, and RGB values corresponding to each patch are output. By disposing the image inside the color image forming apparatus, it becomes possible to automatically detect the fixed image before discharging it to the paper discharge unit. When the color sensor 100 actually detects the color on the recording material P, a color detection operation command is issued from the control unit of the image forming apparatus, and the color sensor 100, the counter plate 101, and the like are driven by a drive source (not shown). Comes in contact with light pressure. Here, the color sensor 100 is in contact with the counter plate 101 at a light pressure while the recording material P is being conveyed while the recording material P is being transported while the distance from the color sensor 100 is kept constant while preventing the paper jam when the recording material P enters. This is to suppress both fluttering and to perform color detection with good accuracy.

  FIG. 10 shows a cross-sectional view of the color sensor 100.

  A color sensor 100, a white LED 102 as a light emitting element, and a charge storage sensor 103a with an on-chip filter of three or more colors such as RGB as a light receiving element are used. The white LED 102 is incident on the recording medium P on which the test chart after fixing is formed at an angle of 45 degrees, and the intensity of diffuse reflected light in the 0 degree direction is detected by the charge storage sensor 103a with an RGB on-chip filter. The light receiving portion of the charge storage type sensor 103a with RGB on-chip filter is a pixel independent of RGB like 103b.

  The light receiving element may be a photodiode. A plurality of RGB three-pixel sets may be arranged. Further, a configuration in which the incident angle is 0 degree and the reflection angle is 45 degrees may be employed. Furthermore, you may comprise by LED which emits light of 3 or more colors, such as RGB, and a sensor without a filter. Furthermore, a spectrophotometer including a white light source such as a halogen lamp as a light emitting unit and a spectroscope as a light receiving unit may be used.

  Next, the timing and measuring method for actually measuring the reflectance of the recording material P using the above-described two optical sensors (media sensor 71 and color sensor 100) will be described. In the second embodiment, unlike the first embodiment, both sensors are arranged in the conveyance path of the recording medium. Therefore, when there is a double-sided printing command from the image processing unit, the image reserved portion of the first page of the print job is automatically used to detect a plurality of points in the recording material P being conveyed, and the average of the results A method of storing a value as an output of each sensor is adopted. (During normal printing, detection is performed with the color sensor 100 and the color sensor facing plate 101 that are separated from each other being in contact with only the first page.) Therefore, when a reference recording material Q described later is used normally The image forming apparatus can be kept in an ideal state without conscious adjustment.

<Configuration Example of Control Unit of Image Forming Apparatus of Present Embodiment>
Since the configuration example of the control unit of the image forming apparatus according to the second embodiment is similar to that shown in FIG. 1A, detailed description is omitted here.

  In the second embodiment, S3 and S4 are used instead of S1 and S2 in the first embodiment. In other words, the image scanner S1 having the reference plate of the first embodiment is a color sensor S3 having a reference plate in the second embodiment, and the media sensor S2 having no reference plate of the first embodiment is a color having no reference plate in the first embodiment. Replaced by sensor S4. Further, the light emitting unit 102 of the color sensor and the light receiving unit 103a of the color sensor are used. Further, the light receiving outputs Om_int (S3) 23f and 24e of the reference recording material Q before assembly, the media sensor output ratio thresholds (z1, z2) 23p and 24i, and the media sensor output ratio thresholds (a1, a2) 23q and 24j are also used. Is done.

(Variables used in the control unit)
FIG. 6 is a table describing the variable list used in the description of the second embodiment and the description thereof. However, in the table, in the table, the media sensor 71 with the reference plate is represented by S3, and the color sensor 100 without the reference plate is represented by S4.

<Operation Example of Image Forming Apparatus of this Embodiment>
FIG. 7 is a flowchart showing an example of the procedure of the optical sensor adjustment method of the image forming apparatus according to the second embodiment. Each step will be described below in order. As in the first embodiment, the adjustment step according to the second embodiment is roughly divided into two steps before assembly of the image forming apparatus and when the product is used.

(Example procedure before assembly)
First, each step before the assembly of the image forming apparatus will be described.

  In step S31, the reference plate 70 disposed opposite to the media sensor 71 is measured using a pair of media sensor 71 and color sensor 100 actually disposed in the image forming apparatus. At this time, the power source for driving each sensor and the electrical circuit of the measurement system preferably have the same configuration as when each sensor is arranged in the image forming apparatus. However, if the correlation representing the measurement condition difference and the measurement configuration difference after both sensors are incorporated in this STEP and the image forming apparatus is known in advance, it can be corrected even when the product is used. .

  In step S32, each sensor reference plate output (Oint (S1), Oint (S2)) and reference plate measurement conditions (Pint (S1), Pint (S2)) of step S31 are stored in the memory attached to each sensor (not shown). It memorize | stores in the area | region or the memory area of a control part.

  Next, in step S33, the background of the reference recording material Q is measured by a sensor provided with a reference plate (in the second embodiment, the media sensor 71). In step S34, as in step S32, the reference recording material Q output (Om_int (S1)) and the reference recording material Q measurement condition (Pm_int (S1)) of the media sensor 71 are stored in the main body memory (not shown).

  Here, the reason why the detection result of the reference recording material Q is stored before assembly is to compare the output of the reference recording material Q measured at an arbitrary timing during use of the product with the output value before assembly. . Therefore, it is desirable that the quality of the reference recording material Q is of a high quality that is unlikely to vary during manufacturing and change with time. After the above steps S31 to S34 are performed, the image forming apparatus is assembled into a product.

(Example of detection control procedure when using the product)
Thereafter, in the environment where the product is used, the reference recording material Q is again measured by each sensor in step S35.

  Next, in step S36, the output result (Om_cur (S1) and Om_cur (S2)) of the reference recording material Q, which is the measurement result of step S35, is used as the reference plate output result (Oini (S1)) of each sensor before assembly. Compare with Oini (S2)). However, the light quantity of each sensor when measuring the reference recording material Q is Pcur (S1) and Pcur (S2), respectively, and t (fixed) to the light quantity Pint (S1) and Pint (S2) when measuring the reference plate before assembly. Value).

  Specifically, as shown in the following (Formula 5), each sensor output ratio of the reference recording material Q falls within a certain range with respect to each sensor output ratio when the reference plate before assembly is measured. Determine whether or not. Here, the lower limit threshold is represented by x1, and the upper limit threshold is represented by x2.

x1 <{(0m_cur (S2) / Om_cur (S1)) / (Oini (S2) / Oini (S1))} <x2 (Formula 5)
In the second embodiment, x1 = 0.9 and x2 = 1.1. In this step, that is, it is determined whether the relationship between the output ratios of the respective sensors that have detected the same reference plate before product assembly is maintained at any timing after the product is completed. In addition, the output ratio of each sensor is calculated using the same reference recording material Q instead of the reference plate. Here, the calculated value (which may be a ratio or a difference) is referred to as a first value representing a difference, and a threshold value that defines a range is referred to as a first threshold value.

  Therefore, in step S36, if the condition of (Formula 5) is satisfied, it can be considered that each sensor maintains the state before assembly. In that case, the sensor 2 (corresponding to the color sensor 100 in the present embodiment) in which the reference plate is not disposed to face the same is the same as the case where the reference plate is present based on the value stored in step S32. It can be measured with high accuracy.

  On the other hand, it is a case where (Equation 5) cannot be satisfied, that is, a case where it is determined that it is not the same as the state before assembly. In this case, it is specified which sensor of the media sensor 70 and the color sensor 100 has changed, or whether the reference plate itself has become dirty, and the configuration of the sensor or the cleaning of the reference plate is made to the user of the image forming apparatus. It is necessary to encourage them. Therefore, as step S37, the output value of the measurement result of the reference recording material Q measured in step S33 and step S35 is compared.

  Specifically, as in (Expression 6), it is determined whether or not the output ratio of the media sensor 71 of the reference recording material Q before assembly and the present is within a certain range. Here, the lower limit threshold is represented as z1, and the upper threshold is represented as z2.

z1 <Om_cur (S1) / Om_ini (S1) <z2 (Formula 6)
In the second embodiment, z1 = 0.925, z2 = 1.075, which is smaller than the allowable range | x1-x2 | in step S36. The reason for this is that in (Equation 6), the detection reproducibility error of the media sensor 71, the allowable change amount, and the individual variation of the reference recording material Q may be considered. On the other hand, in (Equation 5), it is necessary to consider the detection position error of the recording medium P in addition to the detection reproducibility error and the allowable change amount of the media sensor 71 and the color sensor 100, respectively. That is, in this step, it is determined whether or not the absolute value of the output of the media sensor 71 (sensor 1) that has detected the same reference recording material Q as before the product assembly is maintained at an arbitrary timing when the product is used. Here, the calculated value (which may be a ratio or a difference) is referred to as a third value representing a difference, and a threshold value that defines a range is referred to as a third threshold value.

  Therefore, if the condition of (Equation 6) cannot be satisfied in step S37, it can be determined that the media sensor 71 has changed over time. In this case, in step S38, the media sensor 71 provided with the reference plate is calibrated. A specific calibration method may be the same as in the first embodiment, and is omitted here. In step S39, the calibration condition of the media sensor 71 is stored in the main body memory, and the sensor in the image forming apparatus can be kept in an ideal state.

  On the other hand, when the condition of (Equation 6) is satisfied in step S37, the media sensor 71 can be regarded as being in the same state as before assembly. In this case, it can be estimated that the reason why (Equation 5) is not satisfied in step S36 is that the reference plate itself is dirty or the color sensor 100 is changing with time.

  Therefore, this time, in step S41, it is determined whether or not the ratio with the previous (initial) reference plate output is within a threshold value. Specifically, as in (Expression 7), it is determined whether or not the output ratio of the media sensor 71 of the reference plate before assembly and the present is within a certain range. Here, the lower limit threshold is represented by a1, and the upper limit threshold is represented by a2. However, at this time, the light emission amount that the media sensor 71 uses for the reference plate measurement is the same Pint (S1) as before assembly.

a1 <Ocur (S1) / Oini (S1) <a2 (Formula 7)
In the second embodiment, a1 = 0.95 and a2 = 1.05, which are smaller than the allowable range | x1-x2 | in step S36 and further to the allowable range | z1-z2 | in step S37. This is because, for the same reason as described in step S37, the detection error to be considered in step S41 is smaller than in other cases. That is, in this step, it is determined whether or not the absolute value of the output of the media sensor 71 (sensor 1) that has detected the same reference plate as before product assembly is maintained at an arbitrary timing after the product is completed. Here, based on the measurement comparison results before and after the assembly of the reference recording material Q in step S37, it has been found that the media sensor 71 has not changed over time. Here, the calculated value (which may be a ratio or a difference) is referred to as a second value representing a difference, and a threshold value that defines a range is referred to as a second threshold value.

  Therefore, in step S41, when the condition of (Expression 7) cannot be satisfied, it can be determined that the media sensor 71 does not change with time but the reference plate itself is dirty. Therefore, in this case, in step S42, the user is notified through the control part of the image forming apparatus that the reference plate is dirty. Examples of the notification means include an operation panel of the image forming apparatus, output to a client or host PC screen via a driver, or e-mail.

  On the other hand, if the condition of (Expression 7) is satisfied in step S41, it can be determined that the color sensor 100 has changed with time, and the color sensor 100, which is a sensor that does not include a reference plate, is calibrated. A specific calibration method may be the same as in the first embodiment, and is omitted here. In step S44, the calibration condition of the color sensor 100 is stored in the main body memory, and the sensor in the image forming apparatus can be kept in an ideal state.

  In the first and second embodiments described so far, the configuration in which the number of optical sensors in the image forming apparatus is two and the reference plate is provided only opposite one of the optical sensors has been described. However, the present invention is not limited to this configuration. For example, an optical sensor that does not include two or more reference plates may be used for one optical sensor having a reference plate. In this case, the reference plate output values of the sensor having the reference plate and the sensor not having the reference plate may be stored in advance.

  As described above, in the second embodiment, the two optical sensors are arranged in the image forming apparatus, and the reference plate is arranged only on one sensor facing surface, and the media sensor 71 including the reference plate before assembly is used. The sensor output result of the reference recording material P is stored in advance. As a result, it is possible to reduce variations in detection accuracy of both sensors, and to automatically determine whether the reference plate itself is dirty, the sensor should be calibrated, and which sensor is the calibration target, and its The method has been explained.

  As a result, in addition to the effects of the first embodiment, the degree of freedom of design of the arrangement position of the optical sensor that can be detected with high accuracy can be increased, and the load to the user is reduced by having the function of automatic correction. be able to.

  In addition, the present invention may be applied to a system or an integrated device composed of a plurality of devices (for example, a host computer, an interface device, a printer, etc.) or an apparatus composed of a single device.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus. Needless to say, this can also be achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. This includes the case where the operating system (OS) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Needless to say.

  Further, the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU provided in the function expansion card or function expansion unit performs part or all of the actual processing. It goes without saying that the case where the functions of the above-described embodiments are realized by such processing is also included.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

3 is a block diagram illustrating a configuration example of a control unit of the image forming apparatus according to the present exemplary embodiment. FIG. It is a figure which shows the table | surface which described the variable list used by description of this Embodiment 1, and its description. 6 is a flowchart illustrating an example of a procedure of an adjustment method according to the first embodiment. 1 is a schematic cross-sectional view illustrating an example of the overall configuration of an electrophotographic image forming apparatus according to a first embodiment. It is a figure which shows the structural example of the image scanner 12a which concerns on this Embodiment 1. FIG. It is a figure which shows the structural example of the media sensor 71 which concerns on this Embodiment 1. FIG. It is a figure which shows the table | surface describing the variable list used by description of this Embodiment 2, and its description. It is a flowchart which shows the example of a procedure of the adjustment method which concerns on this Embodiment 2. FIG. 3 is a schematic cross-sectional view showing an example of the overall configuration of an electrophotographic image forming apparatus according to Embodiment 2. FIG. It is a figure which shows the structural example of the media sensor 71 which concerns on this Embodiment 2. FIG. It is a figure which shows the structural example of the color sensor 100 which concerns on this Embodiment 2. FIG.

Explanation of symbols

12a Image Scanner 13 Reference Plate of Image Scanner 12a in Embodiment 1 71 Media Sensor 100 Color Sensor 70 Reference Plate of Media Sensor 71 in Embodiment 2

Claims (5)

In the image forming apparatus having a plurality of detecting means for detecting the amount of light emission or optical reflectivity can be adjusted in light output,
The installed on the opposite surface of the one sensing means of the plurality of detecting means, and the reference plate for correcting the amount of light emission or light reception output of said detecting means,
Storage means for storing detection results obtained by detecting the optical reflectance of the reference plate in advance by the plurality of detection means;
A recording medium detection control unit that controls the plurality of detection units to detect the optical reflectance of the same recording medium, the reference plate stored in the storage unit by the detection unit on which the reference plate is installed Between the detection result of the recording medium and the detection result of the detected recording medium, the detection result of the reference plate stored in the storage means by the detection means not provided with the reference plate, and the detection of the detected recording medium When the first value representing the difference does not fall within the range defined by the predetermined first threshold, the optical reflection of the reference plate is detected by the detection means provided with the reference plate. Detection control means for controlling to detect the rate ;
The detection result of the reference plate stored in the storage means by the detection means provided with the reference plate is compared with the detection result of the detected reference plate, and a second value representing the difference is determined in advance. If it does not fall within the range determined by the second threshold, the detection means on which the reference plate is installed is specified as the detection means for correcting the light emission amount or the light reception output, and a second value representing the difference is determined in advance. If within a range in which the second threshold value is determined, the detection means the reference plate is not installed, specifying means for specifying a detection means to be corrected light emission amount or the light receiving output
An image forming apparatus comprising: a correction unit that corrects the light emission amount or the light reception output of the detection unit specified by the specifying unit. In an image forming apparatus having a plurality of detecting means capable of adjusting the light emission amount or the light receiving output and detecting the optical reflectance,
A reference plate for correcting a light emission amount or a light reception output of the detection means, which is installed on an opposing surface of one detection means of the plurality of detection means;
A memory for storing a detection result obtained by detecting the optical reflectance of the reference plate in advance by the plurality of detection means and a detection result obtained by detecting the optical reflectance of a reference storage medium in advance by the detection means provided with the reference plate. Means,
A recording medium detection control unit that controls the plurality of detection units to detect the optical reflectance of the same recording medium, the reference plate stored in the storage unit by the detection unit on which the reference plate is installed Between the detection result of the recording medium and the detection result of the detected recording medium, the detection result of the reference plate stored in the storage means by the detection means not provided with the reference plate, and the detection of the detected recording medium The first value representing the difference is compared with the result and does not fall within the range defined by the predetermined first threshold value, and is stored in the storage means by the detection means provided with the reference plate. When the detection result of the reference recording medium and the detection result of the detected reference recording medium are compared, and the third value representing the difference falls within the range determined by the predetermined third threshold, The reference plate is placed And detection control means for controlling so as to detect the optical reflectance of the reference plate in the sensing means,
If the third value representing the difference does not fall within the range determined by the predetermined third threshold, the detection means on which the reference plate is installed is identified as the detection means for correcting the light emission amount or the light reception output, When the third value representing the difference falls within a range determined by a predetermined third threshold, the detection result of the reference plate stored in the storage unit by the detection unit provided with the reference plate is detected and detected. When the second value representing the difference does not fall within the range defined by the predetermined second threshold value, the reference plate is identified as dirty and represents the difference. When the second value falls within a range determined by a predetermined second threshold value, a specifying unit that identifies the detection unit on which the reference plate is not installed as a detection unit that should correct the light emission amount or the light reception output ;
An image forming apparatus comprising: a correction unit that corrects the light emission amount or the light reception output of the detection unit specified by the specifying unit. It said plurality of detecting means for detecting the optical reflectance, the image forming apparatus according to claim 1 or 2, characterized in that it comprises an image scanner to read an image from an original. It said plurality of detecting means for detecting the optical reflectance, the image forming apparatus according to any one of claims 1 to 3, characterized in that it comprises the placed detection means in the conveying path of the recording medium. The detection means arranged in the conveyance path of the recording medium includes at least one of a media sensor that detects an optical reflectance of the recording medium and a color sensor that detects an optical reflectance of an image formed on the recording medium. The image forming apparatus according to claim 4 .

Images