Image forming apparatus

Abstract

To provide an image forming apparatus that can check a state of an odor detection unit and appropriately correct a detection result in a configuration in which various types of control are performed according to the detection result of the odor detection unit.SOLUTION: An image forming apparatus comprises an image forming unit, a fixing unit, an odor detection unit, and a control unit. The odor detection unit outputs an output value according to the strength of odor generated from a recording medium passing through the fixing unit. The control unit executes predetermined odor reduction processing when determining that odor with a standard value or more is generated on the basis of detection output from the odor detection unit. The control unit acquires an initial output correlation that is a relation between a change in the output value from the odor detection unit and at least one of a change in image density and a change in a fixing temperature of the fixing unit, at the start of use of the odor detection unit, and a post-endurance output correlation that is a relation between a change in the output value and at least one of a change in image density and a change in the fixing temperature at predetermined timing after the start of use of the odor detection unit, and corrects a detection output value from the odor detection unit.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus that forms an image on a recording medium such as paper, and more particularly to an image forming apparatus that performs various controls depending on the strength of odor detected by an odor detection unit during image formation. [Background technology]

[0002] In image forming devices such as printers, copiers, facsimiles, or multifunction devices equipped with these functions, odorous substances in heated toner may vaporize and generate odors during the fixing process for fixing unfixed toner on a recording medium during image formation. If the odor is strong, there is a problem that it may cause discomfort to users of the image forming device.

[0003] Various measures have been proposed to deal with odors that occur during image formation. For example, Patent Document 1 discloses an image forming apparatus and an exhaust control method for the image forming apparatus that has an odor sensor that detects odors around the apparatus body and a human presence sensor that detects people, and that directs the exhaust direction of the exhaust unit to an uninhabited area where the human presence sensor has not detected people when the odor sensor detects a strong odor.

[0004] Patent document 2 discloses an image forming apparatus equipped with a control unit that recognizes odor intensity based on the output of an odor sensor and sets the printing speed so that the recognized odor intensity does not exceed a predetermined target value.

[0005] Patent document 3 discloses an image forming device that determines whether or not a standard level of odor is generated from paper when printed based on the output of an odor sensor, and when it is determined that a standard level of odor is generated, sends an operation start command to a communication unit to operate an external device that moves air to reduce odors in the room. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2021-182117 A [Patent Document 2] JP 2020-118884 A [Patent Document 3] JP 2020-71253 A Summary of the Invention [Problem to be solved by the invention]

[0007] As in Patent Documents 1 to 3, methods have been proposed for detecting odor substances generated during image formation and performing various controls based on the detection results, but there is no guarantee that the detection output of the odor detection unit that detects the odor substances is always accurate. Therefore, if the detection output of the odor detection unit deviates from the correct output value, appropriate control cannot be performed.

[0008] In consideration of the above problems, the present invention aims to provide an image forming device that is configured to perform various controls depending on the intensity of odor detected by the odor detection unit during image formation, and that can check the state of the odor detection unit and appropriately correct the detection results. [Means for solving the problem]

[0009] In order to achieve the above object, the first configuration of the present invention is an image forming apparatus including an image forming unit, a fixing unit, an odor detection unit, and a control unit. The image forming unit includes a photoconductor having a photosensitive layer on its surface, a charging member for charging the photoconductor, an exposure device for forming an electrostatic latent image on the surface of the photoconductor charged by the charging member, and a developing device for supplying toner to the photoconductor to develop the electrostatic latent image into a toner image. The fixing unit heats and pressurizes the recording medium on which the toner image has been formed in the image forming unit. The odor detection unit outputs an output value according to the intensity of the odor generated from the recording medium that has passed through the fixing unit. The control unit determines whether an odor exceeding a standard level is generated based on the detection output of the odor detection unit, and executes a predetermined odor reduction process when it is determined that an odor exceeding the standard level is generated. The control unit acquires an initial output correlation, which is the relationship between the change in output value of the odor detection unit and at least one of the change in image density of a toner image formed by the image forming unit and the change in fixing temperature of the fixing unit when use of the odor detection unit begins, and stores it in the memory unit.After use of the odor detection unit begins, at a predetermined timing, the control unit acquires a post-durability output correlation, which is the relationship between the change in output value and at least one of the change in image density and the change in fixing temperature, and executes a calibration mode in which the detection output value of the odor detection unit is corrected by comparing it with the initial output correlation stored in the memory unit. Effect of the Invention

[0010] According to the first aspect of the present invention, the odor detection unit can be stably used for a long period of time by calibrating the odor detection unit at a predetermined timing. Also, by changing at least one of the image density of the toner image and the fixing temperature when the recording medium to which the toner image is transferred passes through the fixing unit, the initial output correlation and the post-durability output correlation are obtained, and the detection output value of the odor detection unit is corrected, so that the odor detection unit can be calibrated with high accuracy without being affected by the recording medium. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a side cross-sectional view showing a schematic configuration of an image forming apparatus 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partially enlarged view of the periphery of the image forming unit P in FIG. [Diagram 3] FIG. 1 is a block diagram showing an example of a control path in an image forming apparatus according to an embodiment of the present invention. [Figure 4] Graph showing the relationship between image density and output value of odor sensor 20 [Diagram 5] FIG. 1 is a diagram showing an example of a reference image Gs used for calibrating the odor sensor 20. [Figure 6] Graph showing the relationship between fixing temperature and output value of odor sensor 20 [Figure 7] Graph showing time progression of the reference correction coefficient M of the odor sensor 20 [Figure 8] 1 is a flowchart showing an example of execution control of a calibration mode of the odor sensor 20 in the image forming apparatus 100 of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [1. Overall configuration of image forming device] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the overall configuration of an image forming apparatus 100 according to a first embodiment of the present invention. Inside the main body of the image forming apparatus (e.g., a monochrome printer) 100, an image forming unit P is disposed that forms a monochrome image through the processes of charging, exposing, developing, and transferring.

[0013] In the image forming section P, a charging device 2, an exposure device 3, a developing device 4, a transfer roller 5, a cleaning device 6, and a static elimination device 7 are arranged along the rotation direction (counterclockwise direction in FIG. 1) of the photosensitive drum 1. In the image forming section P, an image forming process is performed on the photosensitive drum 1 while the photosensitive drum 1 is rotated counterclockwise in FIG.

[0014] When performing a printing operation, image data sent from a higher-level device such as a personal computer is converted into an image signal. Meanwhile, in the image forming section P, the photoconductor drum 1, which rotates in a counterclockwise direction in the figure, is uniformly charged by the charging device 2. Next, an exposure device 3 irradiates the photoconductor drum 1 with laser light based on the image signal, thereby forming an electrostatic latent image based on the image data on the surface of the photoconductor drum 1. Thereafter, toner carried on the developing roller 4a (see FIG. 2) of the developing device 4 is attached to the electrostatic latent image to form a toner image. Toner is supplied to the developing device 4 from a toner container 8.

[0015] As described above, the paper S is transported from the paper storage section 10 toward the image forming section P on which the toner image has been formed, at a predetermined timing, via the paper transport path 11 and the pair of registration rollers 13. The toner image formed on the surface of the photosensitive drum 1 is transferred to the paper S at a nip portion (transfer nip portion N in FIG. 2) between the photosensitive drum 1 and the transfer roller 5. The paper S on which the toner image has been transferred is separated from the photosensitive drum 1 and transported to the fixing section 9 where the toner image is fixed to the paper S by being heated and pressed. The paper S that has passed through the fixing section 9 has its transport direction diverted by a branching guide 16 arranged at a branching portion of the paper transport path 11, and is discharged directly (or after being sent to the reversing transport path 17 and printed on both sides) to the paper discharge section 15 via the pair of discharge rollers 14.

[0016] An odor sensor 20 is disposed upstream of the discharge roller pair 14 in the paper discharge direction. The odor sensor 20 is disposed downstream of the fixing unit 9 so as to face the paper transport path 11, and detects odor substances emitted from the paper S heated in the fixing unit 9. The odor sensor 20 is a sensor that outputs the concentration of an odor substance as a potential difference, such as a semiconductor type, a quartz crystal oscillator type, or a membrane surface stress type (MSS) sensor. The detection output of the odor sensor 20 is sent to the control unit 30 (see FIG. 3).

[0017] A first fan 21 is disposed near the discharge roller pair 14. The first fan 21 controls the airflow around the paper discharge section 15 to stabilize the discharge state of the paper S. The first fan 21 also takes in outside air to reset the odor substances around the odor sensor 20 when performing calibration of the odor sensor 20, which will be described later.

[0018] A second fan 22 is disposed near the exposure device 3. The second fan 22 cools the inside of the image forming apparatus 100 by discharging the air inside the image forming apparatus 100 that has been heated by the exposure device 3 and the fixing unit 9 to the outside.

[0019] Fig. 2 is a partially enlarged view of the periphery of the image forming unit P in Fig. 1. The photosensitive drum 1 is an amorphous silicon photosensitive body in which a photosensitive layer 1b including a photoconductive layer made of an amorphous silicon layer is laminated on the outer peripheral surface of a drum base tube 1a made of, for example, aluminum, and the photosensitive layer 1b is charged to a predetermined surface potential by a charging device 2. Then, an electrostatic latent image with attenuated charge is formed on the surface of the photosensitive layer 1b that has been subjected to laser light L from an exposure device 3 (see Fig. 1).

[0020] The charging device 2 has a charging roller 23 and a charging cleaning roller 25. The charging roller 23 is made of, for example, conductive rubber, and is disposed so as to abut against the photosensitive drum 1. As shown in FIG. 2, when the photosensitive drum 1 rotates in a counterclockwise direction, the charging roller 23 in contact with the surface of the photosensitive drum 1 is rotated in a clockwise direction. At this time, a predetermined charging voltage is applied to the charging roller 23, so that the photosensitive layer 1b of the photosensitive drum 1 is uniformly charged. In addition, as the charging roller 23 rotates, the charging cleaning roller 25 in contact with the charging roller 23 is rotated in a counterclockwise direction to remove foreign matter adhering to the surface of the charging roller 23.

[0021] The developing device 4 includes a developing roller 4a disposed opposite the photosensitive drum 1. A predetermined developing voltage, which is a DC voltage Vdc superimposed with an AC voltage Vac, is applied to the developing roller 4a to cause toner to adhere to the developing roller 4a. Then, the toner is moved from the developing roller 4a to the photosensitive drum 1 by the potential difference (development potential difference) between the developing roller 4a and the photosensitive drum, and the electrostatic latent image formed on the surface of the photosensitive drum 1 is developed into a toner image. Note that a conventionally known developing device can be used as the developing device 4.

[0022] The cleaning device 6 includes a recovery spiral 61, a cleaning blade 62, a rubbing roller (cleaning roller) 63, and a scraper 64. The recovery spiral 61 is disposed toward the lower inside of the housing, and rotates in a predetermined direction to transport the recovered toner in one direction of the paper width (direction perpendicular to the paper surface of FIG. 2) and send it out to a waste toner container (not shown).

[0023] The static eliminator 7 is disposed downstream of the cleaning device 6 in the rotation direction of the photosensitive drum 1. The static eliminator 7 uses an LED (light emitting diode) and irradiates the photosensitive drum 1 with static elimination light (erase light) to remove residual charges on the surface of the photosensitive layer 1b, preparing for the charging process during the next image formation operation.

[0024] The image density sensor 70 is disposed upstream of the transfer roller 5 (transfer nip portion N) in the rotation direction of the photoconductor drum 1. An optical sensor equipped with a light-emitting element such as an LED and a light-receiving element such as a photodiode is generally used as the image density sensor 70. When measuring the amount of toner adhesion on the intermediate transfer belt 8, when the light-emitting element irradiates each patch image (reference image) formed on the photoconductor drum 1 with measurement light, the measurement light is reflected by the toner and the drum surface and enters the light-receiving element.

[0025] The light reflected from the toner and drum surface includes specular and diffuse reflections. The specular and diffuse reflections are separated by a polarizing separation prism and then enter separate light receiving elements. Each light receiving element photoelectrically converts the received specular and diffuse reflections and outputs an output signal to the control unit 30 (see FIG. 3).

[0026] 3 is a block diagram showing an example of a control path in the image forming apparatus 100 of the first embodiment. Note that, since various controls are performed on each part of the image forming apparatus 100 when the image forming apparatus 100 is used, the control path of the entire image forming apparatus 100 becomes complicated. Therefore, the following description will focus on the parts of the control path that are necessary for implementing the present invention. Also, descriptions of parts that have already been described will be omitted.

[0027] Based on various control programs related to the overall image formation process stored in ROM 31 and RAM 32, the control unit 30 adjusts image formation conditions such as the drive of the photosensitive drum 1, the supply of toner to the developing device 4, the applied voltage of a voltage control circuit 34 which applies a charging voltage, a developing voltage and a transfer voltage to the charging roller 23, the developing roller 4a and the transfer roller 5, respectively, and the laser output of the laser light L (see Figure 2) emitted from the exposure device 3.

[0028] The control unit 30 is also connected to a reader / writer module 36. The reader / writer module 36 reads and rewrites information stored in a wireless tag 35 attached to the toner container 8 as a storage device.

[0029] The operation unit 37 has a liquid crystal display unit that indicates the status of the image forming apparatus 100 and displays the image formation status and the number of copies printed, LEDs that indicate various states, a stop / clear button for stopping image formation, a reset button for resetting the settings of the image forming apparatus 100 to the default state, etc. (none of which are shown). The counter 39 cumulatively counts the number of printed sheets.

[0030] [2. Odor reduction processing based on the detection results of the odor sensor] In the image forming apparatus 100 of this embodiment, the control unit 30 determines the strength of the odor emanating from the paper S passing through the fixing unit 9 based on the detection output of the odor sensor 20. In other words, it determines whether or not a threshold level of odorous substance is being emanated from the paper S. When it is determined that a threshold level of odorous substance is being emanated, a process is performed to reduce the odor.

[0031] For example, the lower the fixing temperature of the fixing unit 9, the more the generation of odorous substances is suppressed, but if the printing speed is the same, lowering the fixing temperature may not sufficiently melt the unfixed toner on the paper S. In this case, slowing the printing speed increases the time it takes to heat the toner on the paper S, so that the unfixed toner can be sufficiently melted even if the fixing temperature is lowered. Therefore, when the odorous substances detected by the odor sensor 20 are equal to or higher than the standard, the control unit 30 lowers the fixing temperature and slows the printing speed.

[0032] Furthermore, the higher the image density, the greater the amount of unfixed toner heated by the fixing unit 9, which promotes the generation of odorous substances. Therefore, when the amount of odorous substances detected by the odor sensor 20 is equal to or greater than a standard, the control unit 30 reduces the image density to a degree that does not affect the image. In addition, the rotation speed of the first fan 21 and the second fan 22 may be increased to promote the discharge of odorous substances from within the image forming apparatus 100, or printing may be stopped if the amount of odorous substances significantly exceeds the standard.

[0033] Alternatively, the control unit 30 can be made to communicate with an external device (not shown) that reduces odors, and when the odor substance detected by the odor sensor 20 is equal to or greater than a standard, the control unit 30 can send an operation start command to the external device. For example, when the external device is a ventilation fan, a ventilation start command is sent to the ventilation fan. When the external device is an air purifier, a command to start suctioning, purifying, and exhausting air is sent to the air purifier.

[0034] When performing various processes based on the detection output of the odor sensor 20 as described above, it is assumed that the odor sensor 20 always detects odor substances accurately. However, when the odor sensor 20 is used for a long period of time, the detection sensitivity gradually decreases. As a result, the detection output may deviate from the actual value of the odor substance, making it impossible to perform appropriate processing.

[0035] [3. Calibration of odor sensor] In the image forming apparatus 100 of this embodiment, the odor sensor 20 is calibrated, and the calibration results are transmitted to the control unit 30. The control unit 30 corrects the odor sensor 20 based on the calibration results. Specifically, the control unit 30 corrects the detection output of the odor sensor 20 based on the calibration results. The procedure for performing the calibration of the odor sensor 20 will be described below.

[0036] [3-1. Calibration by image density] As a first method, a description will be given of a case where the image density (developing voltage) is changed to calibrate the odor sensor 20. First, at the beginning of use of the image forming apparatus 100 (when use of the odor sensor 20 begins), the relationship between the image density change and the output value of the odor sensor 20 (initial output correlation) is obtained.

[0037] Specifically, a reference image Gs is formed on the photoconductor drum 1, in which the image density is changed in stages by changing the development voltage (DC voltage) in multiple stages. Then, the image density of the reference image Gs is measured by the image density sensor 70. Next, the reference image Gs is transferred to a sheet S, and the odor generated when the sheet S passes through the fixing unit 9 is detected by the odor sensor 20. The relationship between the output value of the image density sensor 70 and the output value of the odor sensor 20 is expressed by approximation formula (1) shown by the dashed line in FIG. 4, and is stored in advance in the ROM 31 or the RAM 32. y = ax + b (1) however, x; image density y: Output value of the odor sensor a, b; constant It is.

[0038] Fig. 5 is a diagram showing an example of a reference image Gs used for calibration. As shown in Fig. 5, the reference image Gs used for calibration of the odor sensor 20 preferably has a pattern in which black vertical stripes are printed along the paper transport direction (the direction of the white arrow in Fig. 5) at a position that overlaps with the odor sensor 20 in the width direction of the paper S (the vertical direction in Fig. 5).

[0039] When the first fan 21 is installed to control the airflow near the paper discharge unit 15 as in this embodiment, it can be used for a reset operation to remove odor substances near the odor sensor 20 during the calibration mode. Specifically, the control unit 30 performs a reset operation to rotate the first fan 21 until the output value of the odor sensor 20 attenuates to within ±10% of the output value before the start of calibration. The first fan 21 is stopped while the odor sensor 20 is detecting an odor.

[0040] Next, after starting to use the odor sensor 20, when it is time to perform calibration of the odor sensor 20, the system transitions to calibration mode. Then, the relationship between the image density change and the output value of the odor sensor 20 (post-durability output correlation) is obtained. If the toner container 8 being used is a predetermined one (genuine product), the calibration is performed at a timing that is predetermined for each image forming device 100, such as every time the cumulative number of printed sheets since the previous calibration reaches 10k (10,000).

[0041] The calibration mode is also executed when the toner container 8 is replaced with a toner container other than the predetermined one (non-genuine product). When the toner container 8 is replaced with a non-genuine product, the toner supplied to the developing device 4 changes, and this may change the state of the odor emitted when passing through the fixing unit 9. Therefore, the calibration mode is executed at the time the toner container 8 is replaced. Alternatively, the calibration mode can also be executed by an input operation on the operation unit 37 by the user or a serviceman.

[0042] Specifically, when the timing for performing calibration arrives, the control unit 30 changes the image density by changing the development conditions (development voltage [V]) to form a reference image Gs as shown in FIG. 5. Then, the image density sensor 70 measures the image density of the reference image Gs. Next, the reference image Gs is transferred to a sheet S, and the odor generated when the sheet S passes through the fixing unit 9 is detected by the odor sensor 20. That is, if the detection sensitivity of the odor sensor 20 changes due to durability, the output value of the odor sensor 20 also changes. The relationship between the output value of the image density sensor 70 and the output value of the odor sensor 20 at this time is expressed by approximation formula (2) shown by a solid line in FIG. 4, and stored in the ROM 31 or the RAM 32. y = mx + n (2) however, x; image density y: Output value of the odor sensor m, n; constant It is.

[0043] It is preferable to change the image density each time a reference image Gs is printed, perform the above-mentioned reset operation between each reference image Gs, and print the next reference image Gs after confirming that the output value of the odor sensor 20 has attenuated to within ±10% of the output value before the start of calibration. Also, in order to make the odor sensor 20 less susceptible to the effects of odor history, it is preferable to form the reference images Gs in order from lowest image density.

[0044] In addition, in order to remove initial noise from the odor sensor 20, the output value of the odor sensor 20 is calculated by subtracting the output value of the odor sensor 20 before the start of calibration from the maximum value of the odor when the paper S is passed through, or the average value of the odor for a period equivalent to 1 / 2 the paper passing time before and after the maximum value.

[0045] The control unit 30 compares the approximate formula (2) obtained during calibration with the previously stored approximate formula (1) to obtain the correction coefficient C (=a / m). The correction coefficient C is obtained from the slope of the approximate formulas (1) and (2) in order to eliminate the influence of the paper S, whose odor changes depending on the moisture absorption level and type.

[0046] When the relationship of the output value of the odor sensor 20 to the change in image density is expressed as a linear equation such as approximate equations (1) and (2), the influence of the paper S appears in the intercepts b and n. On the other hand, the slopes a and m represent the change in the output value of the odor sensor 20 to the change in image density, and therefore indicate the pure detection sensitivity of the odor sensor 20. For this reason, the sensitivity of the odor sensor 20 is compared between the slope a at the start of use of the odor sensor 20 and the slope m after durability testing. When performing calibration by changing the image density (developing voltage) in two stages, an example of the setting of the developing voltage to change the image density is shown in Table 1.

[0047] [Table 1]

[0048] The setting example shown in Table 1 is the condition when the photosensitive layer 1b is amorphous silicon, the image portion potential VL is 10 V or less, and the ratio of the development voltage is equal to the ratio of the developed amount of toner. When changing the development voltage, it is preferable that the development potential difference Vdc-VL is about twice as large as that in conditions 1 and 2. In order to increase the detection sensitivity of the odor sensor 20, it is preferable that the printing speed is slower than that during normal image formation.

[0049] [3-2. Calibration by Fixing Temperature] As a second method, a description will be given of a case where the fixing temperature is changed to calibrate the odor sensor 20. First, at the beginning of use of the image forming apparatus 100 (when use of the odor sensor 20 starts), the relationship (initial output correlation) between the change in fixing temperature and the output value of the odor sensor 20 is obtained.

[0050] Specifically, a reference image Gs as shown in FIG. 5 is formed on the photoconductor drum 1 with a constant developing voltage (DC voltage) and constant image density, and the reference image Gs is transferred to the paper S. Next, the fixing temperature is changed stepwise in the range of 120 to 180° C., and the odor generated when the paper S passes through the fixing unit 9 is detected by the odor sensor 20. The relationship between the fixing temperature and the output value of the odor sensor 20 is expressed by approximation formula (3) shown by the dashed line in FIG. 6, and is stored in advance in the ROM 31 or RAM 32. y = dx + e (3) however, x: Fixing temperature y: Output value of the odor sensor d, e; constant It is.

[0051] Since the greater the amount of toner in the reference image Gs, the greater the amount of odorous substance generated, the more the measurement accuracy of the odor sensor 20 is increased by using a calibration development voltage that is higher in density than the appropriate image density as the development voltage when forming the reference image Gs. The reset operation during the calibration mode is the same as the calibration by image density.

[0052] Next, after starting to use the odor sensor 20, when it is time to perform calibration of the odor sensor 20, the system transitions to calibration mode. Then, the relationship between the change in fixing temperature and the output value of the odor sensor 20 (post-durability output correlation) is obtained. The timing of performing the calibration is the same as the calibration based on image density.

[0053] Specifically, when it is time to perform calibration, the control unit 30 forms a reference image Gs with a constant image density as shown in FIG. 5, and transfers the reference image Gs to the paper S. Next, the fixing temperature is changed stepwise in the range of 120 to 180° C., and the odor sensor 20 detects the odor generated when the paper S passes through the fixing unit 9. The relationship between the fixing temperature at this time and the output value of the odor sensor 20 is expressed by approximation formula (4) shown by the solid line in FIG. 6, and is stored in the ROM 31 or the RAM 32. y=px+q (4) however, x: Fixing temperature y: Output value of the odor sensor p, q; constants It is.

[0054] The control unit 30 compares the approximate formula (2) obtained during calibration with the approximate formula (1) stored in advance to obtain the correction coefficient C (=d / p). The driving (reset operation) of the first fan 21 between sheets and the processing of the output value of the odor sensor 20 are the same as in the case of calibration by image density. Table 2 shows an example of the setting of the fixing temperature when performing calibration by changing the fixing temperature in two stages.

[0055] [Table 2]

[0056] [3-3. Calibration by image density and fixing temperature] As a third method, a case will be described in which both the image density (development voltage) and the fixing temperature are changed to calibrate the odor sensor 20. First, at the beginning of use of the image forming apparatus 100 (when use of the odor sensor 20 begins), the relationship (initial output correlation) between the change in image density and the change in fixing temperature and the output value of the odor sensor 20 is obtained.

[0057] Specifically, the image density is changed by changing the development conditions (development voltage [V]) on the photoconductor drum 1 to form a reference image Gs as shown in FIG. 5, and the reference image Gs is transferred to the paper S. Next, the fixing temperature is changed stepwise in the range of 120 to 180° C., and the odor generated when the paper S passes through the fixing unit 9 is detected by the odor sensor 20. The relationship between the image density and the output value of the odor sensor 20 is represented by approximate formula (1) shown by the dashed line in FIG. 4, and the relationship between the fixing temperature and the output value of the odor sensor 20 is represented by approximate formula (3) shown by the dashed line in FIG. 6, and these are stored in advance in the ROM 31 or the RAM 32. y = ax + b (1) however, x; image density y: Output value of the odor sensor a, b; constant It is. y = dx + e (3) however, x: Fixing temperature y: Output value of the odor sensor d, e; constant It is.

[0058] Since the greater the amount of toner in the reference image Gs, the greater the amount of odorous substance generated, the more the measurement accuracy of the odor sensor 20 is increased by using a calibration development voltage that results in a higher density than the appropriate image density when forming the reference image Gs. The reset operation during the calibration mode is the same as the calibration based on the image density or fixing temperature.

[0059] Next, after starting to use the odor sensor 20, when it is time to perform calibration of the odor sensor 20, the system transitions to calibration mode. Then, the relationship between the image density change and the fixing temperature change and the output value of the odor sensor 20 (post-durability output correlation) is obtained. The timing of performing the calibration is the same as the calibration based on the image density or fixing temperature.

[0060] Specifically, when the timing for performing calibration arrives, the control unit 30 changes the image density to form a reference image Gs as shown in FIG. 5, and transfers the reference image Gs to the paper S. Next, the fixing temperature is changed stepwise in the range of 120 to 180° C., and the odor sensor 20 detects the odor generated when the paper S passes through the fixing unit 9. The relationship between the image density and the output value of the odor sensor 20 at this time is represented by approximation formula (2) shown by a solid line in FIG. 4, and the relationship between the fixing temperature and the output value of the odor sensor 20 is represented by approximation formula (4) shown by a solid line in FIG. 6, and these are stored in the ROM 31 or the RAM 32. y = mx + n (2) however, x; image density y: Output value of the odor sensor m, n; constant It is. y=px+q (4) however, x: Fixing temperature y: Output value of the odor sensor p, q; constants It is.

[0061] The control unit 30 compares the approximate expressions (2) and (4) obtained during calibration with the previously stored approximate expressions (1) and (3) to obtain the correction coefficient C (=(a×d) / (m×p)). The driving (reset operation) of the first fan 21 between sheets and the processing of the output value of the odor sensor 20 are the same as in the case of calibration by image density. Table 3 shows examples of settings for the developing voltage and fixing temperature when calibration is performed by changing the image density (developing voltage) and fixing temperature in two stages.

[0062] [Table 3]

[0063] [3-4. Control of image forming device using correction coefficient] The control unit 30 multiplies the actual output value of the odor sensor 20 by the calculated correction coefficient C (=a / m or (a×d) / (m×p)) to calculate a corrected output value of the odor sensor 20. Then, based on the calculated corrected output value, processing is performed to reduce the odor. Specifically, if the corrected output value is equal to or greater than a reference value, processing is performed to reduce the odor, such as slowing down the printing speed and lowering the fixing temperature, lowering the image density to a degree that does not affect the image, increasing the rotation speed of the first fan 21 and the second fan 22, and stopping printing.

[0064] If the toner container 8 is a predetermined one (genuine product), the correction coefficient C calculated by the above procedure and the correction output value calculated using the correction coefficient C are valid. However, for a toner container 8 that is not predetermined (non-genuine product), the correction coefficient C cannot be used. Therefore, when the control unit 30 determines that the toner container 8 is a non-genuine product, it uses the reference correction coefficient M (=exp(t / R)) previously stored in the ROM 31 or the like.

[0065] 7 is a graph showing the time progression of the reference correction coefficient M of the odor sensor 20. The reference correction coefficient M is determined by measuring the degree of decrease in the detection sensitivity of the odor sensor 20 during the manufacture of the image forming apparatus 100, and is stored in the ROM 31 or the RAM 32. As shown in FIG. 7, the reference correction coefficient M increases over time due to deterioration (decrease in sensitivity) of the odor sensor 20 over time.

[0066] The determination as to whether the toner container 8 is a genuine product or a non-genuine product is made, for example, by reading information on a wireless tag 35 attached to the toner container 8 using a reader / writer module 36 (see FIG. 3 for both). In addition, depending on whether the toner container 8 is a genuine product or a non-genuine product, the following cases are distinguished.

[0067] If the toner container 8 is determined to be a genuine product, the control unit 30 calibrates the odor sensor 20 to obtain the correction coefficient C. Then, the control unit 30 calculates a corrected output value by multiplying the output value of the odor sensor 20 by the correction coefficient C. However, if the ratio of the correction coefficient C to the reference correction coefficient M exceeds a certain range (e.g., ±30%), there is a possibility that the odor sensor 20 is broken, or that the toner container 8 has been determined to be a genuine product, but the toner is different. Therefore, the control unit 30 calculates the corrected output value using the reference correction coefficient M, and notifies the user of the abnormality by issuing an alarm, etc.

[0068] When it is determined that the toner container 8 is a non-genuine product, the control unit 30 calculates a corrected output value using a reference correction coefficient M stored in advance.

[0069] [3-5. Example of odor sensor calibration control] Fig. 8 is a flowchart showing an example of control of the calibration of the odor sensor 20 based on image density in the image forming apparatus 100 of this embodiment. The procedure for performing the calibration of the odor sensor 20 will be described along the steps of Fig. 8, with reference to Figs. 1 to 7 as necessary. Note that while calibration based on image density has been described in Fig. 8, calibration based on fixing temperature and calibration based on image density and fixing temperature can also be performed in a similar procedure.

[0070] The control unit 30 determines whether or not it is time to perform calibration of the odor sensor 20 (Step S1). If it is time to perform calibration (for example, when the cumulative number of printed sheets is 10k sheets) (Yes in Step S1), the control unit 30 determines whether or not the installed toner container 8 is a genuine product (Step S2).

[0071] If the toner container 8 is a genuine product (Yes in step S2), calibration is started. First, the control unit 30 performs initial detection using the odor sensor 20 (step S3). Specifically, the output value of the odor sensor 20 is obtained without passing the paper S through the fixing unit 9.

[0072] Next, the control unit 30 forms a reference image Gs under condition 1 (step S4). For example, in the case of calibration based on image density, the developing voltage is set to 130 [V] (see Table 1), and a reference image Gs as shown in FIG.

[0073] Next, the control unit 30 performs detection using the odor sensor 20 (step S5). Specifically, the reference image formed in step S4 is transferred onto the paper S, and the odor generated when the paper S passes through the fixing unit 9 is detected by the odor sensor 20. The output value under condition 1 is determined by subtracting the output value of the odor sensor 20 before the start of calibration obtained in step S3 from the maximum output value of the odor sensor 20, or the average output value for a period equivalent to 1 / 2 the paper passing time before and after the maximum value. The output value is stored in ROM 31 or RAM 32.

[0074] Next, the control unit 30 drives the first fan 21 (step S6) to perform a reset operation to remove odor substances near the odor sensor 20. Then, it determines whether the detection output difference between the output value of the odor sensor 20 after the start of the reset operation and the output value of the odor sensor 20 before the start of calibration is within ±10% (step S7). If the detection output difference exceeds ±10% (No in step S7), the first fan 21 continues to be driven.

[0075] If the detection output difference is within ±10% (Yes in step S7), the control unit 30 forms a reference image Gs under condition 2 (step S8). For example, in the case of calibration based on image density, the developing voltage is set to 260 [V] (see Table 1) and a reference image Gs as shown in FIG.

[0076] Next, the control unit 30 performs detection using the odor sensor 20 (step S9). Specifically, the reference image Gs formed in step S8 is transferred onto the paper S, and the odor generated when the paper S passes through the fixing unit 9 is detected by the odor sensor 20. The output value under condition 2 is determined by subtracting the output value of the odor sensor 20 before the start of calibration acquired in step S3 from the maximum output value of the odor sensor 20, or the average output value for a period equivalent to 1 / 2 the paper passing time before and after the maximum value. The output value is stored in ROM 31 or RAM 32.

[0077] Next, the control unit 30 calculates the correction coefficient C (step S10). Specifically, the approximation formula (2) shown in FIG. 4 is obtained from the output values ​​under conditions 1 and 2 obtained in steps S5 and S9. Then, the approximation formula (2) is compared with the approximation formula (1) stored in the ROM 31 or the RAM 32 to calculate the correction coefficient C (=a / m).

[0078] Next, the control unit 30 determines whether the correction coefficient C calculated in step S10 is within ±30% of a reference correction coefficient M (=exp(t / R)) previously stored in the ROM 31 or the like (step S11). If the correction coefficient C is within ±30% of the reference correction coefficient M (Yes in step S11), the control unit 30 calculates a corrected output value of the odor sensor 20 using the correction coefficient C (step S12). Then, processing to reduce the odor is performed based on the calculated corrected output value.

[0079] On the other hand, if the correction coefficient C exceeds ±30% of the reference correction coefficient M (No in step S11), a malfunction of the odor sensor 20 or an abnormality in the toner in the toner container 8 is assumed, so an alarm is issued (step S13) to notify the abnormality, and a correction output value of the odor sensor 20 is calculated using the reference correction coefficient M (step S14). Then, processing to reduce the odor is performed based on the calculated correction output value. Note that instead of an alarm, a message notifying the abnormality may be displayed on the liquid crystal display of the operation unit 37.

[0080] According to the control example shown in Fig. 8, by calibrating the odor sensor 20 at a predetermined timing, the odor sensor 20 can be used stably for a long period of time. The calibration is performed by changing at least one of the image density when creating a reference image Gs for odor detection or the fixing temperature when the paper S onto which the reference image Gs is transferred passes through the fixing unit 9 in two stages to obtain an initial output correlation and an output correlation after durability testing, and calculating a correction coefficient C from the slope of each approximation equation. This allows the odor sensor 20 to be calibrated with high accuracy without being affected by the paper S.

[0081] Furthermore, if the calculated correction coefficient C deviates from a preset reference correction coefficient M by a certain amount or more, an alarm or the like is issued to notify the user of the abnormality and the reference correction coefficient M is used. This makes it possible to prevent the correction output value of the odor sensor 20 from deviating significantly from the actual odor. Also, the user can be promptly notified that an abnormality has occurred in the odor sensor 20 or the toner container 8.

[0082] [4.Other] The present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, the calibration is performed by changing the image density, the fixing temperature, or both in two stages, but the calibration may be performed by changing the image density, the fixing temperature, or both in three or more stages.

[0083] Furthermore, in the above embodiment, the correction coefficient C can be used when the correction coefficient C is within ±30% of the reference correction coefficient M, but the ratio of the correction coefficient C to the reference correction coefficient M can be changed arbitrarily. Similarly, the detection output difference between the output value of the odor sensor 20 after the start of the reset operation and the output value of the odor sensor 20 before the start of calibration, which is used to determine whether or not to continue the reset operation, is not limited to ±10%, and can be changed arbitrarily.

[0084] In addition, the odor sensor 20 can be used to periodically measure the environment of the location where the image forming apparatus 100 is installed and the results can be recorded, making it possible to manage the office environment. For example, the odor sensor 20 can be installed as part of an environment measurement unit that measures indoor illuminance, sound, temperature and humidity, odor, suspended dust, airflow, carbon monoxide, carbon dioxide, formaldehyde, and the like, and can be used separately from the image forming apparatus 100 main body.

[0085] During printing, the odor sensor 20 detects the odor of the toner passing through the fixing unit 9. Then, even after printing is completed, the odor sensor 20 continues to detect for a certain period of time, and if the toner odor does not decrease easily, it can determine that the ventilation environment of the installation environment is poor and recommend that the image forming apparatus 100 be moved to a different location.

[0086] 1, the present invention is of course applicable to various image forming devices having an odor sensor 20, such as color printers, color copiers, digital multifunction machines, and facsimiles. In the case of color printers and color copiers, it is preferable to form the reference image Gs by overlapping toners of all colors in order to increase the amount of toner in the reference image Gs.

[0087] In the above embodiment, the toner container 8 that supplies toner to the developing device 4 is exemplified as a toner storage container that is detachable from the main body of the image forming apparatus 100, but the toner storage container is not limited to the toner container 8. For example, a developing cartridge in which the toner container 8 and the developing device 4 are integrated, and a drum unit in which the photosensitive drum 1 is further integrated, are also included in the toner storage container of the present invention. [Industrial Applicability]

[0088] The present invention can be used in an image forming apparatus that performs various controls depending on the strength of odor detected by an odor detection unit during image formation. By using the present invention, it is possible to provide an image forming apparatus that can check the state of the odor detection unit and appropriately correct the detection result. [Explanation of symbols]

[0089] 1 Photoconductor drum 2. Charging device 4. Developing device 4a Developing roller 5 Transfer roller 6 Cleaning device 8 Toner container (toner storage container) 9 Fixing section 20 Odor sensor (odor detection unit) 21 First Fan 22 Second Fan 30 Control section 31 ROM (memory section) 32 RAM (storage section) 37 Operation section (notification section) 70 Image density sensor 100 Image forming device P Image forming section

Claims

1. A photoreceptor having a photosensitive layer on its surface; a charging member for charging the photoreceptor; an exposure device for forming an electrostatic latent image on the surface of the photoconductor charged by the charging member; a developing device that supplies toner to the photoconductor to develop the electrostatic latent image into a toner image; An image forming unit comprising: a fixing unit that heats and presses the recording medium on which the toner image is formed in the image forming unit; an odor detection unit that outputs an output value according to the intensity of the odor generated from the recording medium that has passed through the fixing unit; A control unit that determines whether an odor equal to or greater than a standard level is being generated based on the detection output of the odor detection unit; and wherein the control unit executes a predetermined odor reduction process when it is determined that an odor equal to or greater than the standard is being generated. The control unit is an initial output correlation, which is a relationship between a change in the output value of the odor detection unit and at least one of a change in image density of the toner image formed by the image forming unit and a change in fixing temperature of the fixing unit when the odor detection unit starts to be used, is obtained and stored in a storage unit; An image forming apparatus characterized in that, at a predetermined timing after starting to use the odor detection unit, a post-durability output correlation, which is the relationship between the change in output value and at least one of the change in image density and the change in fixing temperature, is obtained, and a calibration mode is executed to correct the detection output value of the odor detection unit by comparing it with the initial output correlation stored in the memory unit.

2. The initial output correlation and the post-endurance output correlation are expressed by the following equations (1) and (2), respectively. y=ax+b...(1) y=mx+n...(2) however, x: image density y: Output value of the odor detection unit a, b, m, n; constant When expressed as 2 . The image forming apparatus according to claim 1 , wherein the control unit calculates a corrected output value of the odor detection unit by multiplying the actual output value of the odor detection unit by a correction coefficient a / m.

3. The image forming apparatus according to claim 2, characterized in that the control unit measures the output value under a first condition in which a reference image of a predetermined image density is formed on the recording medium, and then measures the output value under a second condition in which the reference image of the image density different from the first condition is formed on the recording medium, thereby obtaining the initial output correlation and the post-durability output correlation.

4. 3. The image forming apparatus according to claim 2, wherein the image density of the reference image formed under the second condition is higher than the image density of the reference image formed under the first condition.

5. The initial output correlation and the post-endurance output correlation are expressed by the following equations (3) and (4), respectively. y=dx+e...(3) y=px+q...(4) however, x: Fixing temperature y: Output value of the odor detection unit d, e, p, q; constant When expressed as 2 . The image forming apparatus according to claim 1 , wherein the control unit calculates a corrected output value of the odor detection unit by multiplying the actual output value of the odor detection unit by a correction coefficient d / p.

6. The image forming apparatus according to claim 5, wherein the control unit measures the output value under a first condition in which the recording medium onto which a reference image has been transferred is passed through the fixing unit set to a predetermined fixing temperature, and then measures the output value under a second condition in which the recording medium onto which the reference image has been transferred is passed through the fixing unit set to a fixing temperature different from the first condition, thereby obtaining the initial output correlation and the post-durability output correlation.

7. 7. The image forming apparatus according to claim 6, wherein the fixing temperature under the second condition is higher than the fixing temperature under the first condition.

8. The initial output correlation is expressed by the following equations (1) and (3): y=ax+b...(1) however, x: image density y: Output value of the odor detection unit a, b; constant y=dx+e...(3) however, x: Fixing temperature y: Output value of the odor detection unit d, e; constant The post-endurance output correlation is expressed by the following equations (2) and (4). y=mx+n...(2) however, x: image density y: Output value of the odor detection unit m, n; constant y=px+q...(4) however, x: Fixing temperature y: Output value of the odor detection unit p, q: constants When expressed as 2 . The image forming apparatus according to claim 1 , wherein the control unit calculates a corrected output value of the odor detection unit by multiplying the actual output value of the odor detection unit by a correction coefficient (a×d) / (m×p).

9. a toner storage container that stores toner for forming the toner image and is detachable from a main body of the image forming apparatus; The image forming apparatus of claim 2, characterized in that the control unit is capable of determining whether the toner storage container is a genuine product or a non-genuine product, and if the toner storage container is a non-genuine product, calculates a corrected output value of the odor detection unit by multiplying the actual output value of the odor detection unit by a standard correction coefficient previously stored in the memory unit instead of the correction coefficient a / m.

10. The image forming apparatus of claim 2, characterized in that when the correction coefficient a / m deviates by a certain amount or more from a standard correction coefficient previously stored in the memory unit, the control unit calculates a corrected output value of the odor detection unit by multiplying the actual output value of the odor detection unit by the standard correction coefficient instead of the correction coefficient a / m.

11. a notification unit that notifies a user of a state of each unit of the image forming apparatus including the developing device and the odor detection unit; The image forming apparatus according to claim 10, characterized in that, when the correction coefficient a / m deviates from the reference correction coefficient by a certain amount or more, the control unit uses the notification unit to notify of an abnormality in the odor detection unit or an abnormality in the toner used in the developing device.

12. A fan is provided to circulate air around the odor detection unit, An image forming apparatus as described in any one of claims 2 to 11, characterized in that the control unit performs a reset operation to operate the fan to remove odorous substances around the odor detection unit between the measurement of the output value under the first condition and the measurement of the output value under the second condition.

13. The image forming apparatus according to claim 12, characterized in that the reset operation is continued until the output value of the odor detection unit after measuring the output value under the first condition decays to within a range of ±10% of the output value of the odor detection unit before executing the calibration mode.

14. a toner storage container that stores toner for forming the toner image and is detachable from a main body of the image forming apparatus; 2. The image forming apparatus according to claim 1, wherein the control unit is capable of determining whether the toner storage container is a genuine product or a non-genuine product, and executes the calibration mode when the toner storage container is the non-genuine product.

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