Image forming apparatus

Abstract

The present invention provides an image forming apparatus capable of predicting and notifying the user of printing defects. [Solution] An image forming apparatus is provided, comprising an image forming unit that generates heat during printing, an environmental sensor that detects the temperature and humidity around the image forming unit, a CPU, and RAM that stores the detected temperature and humidity. The CPU determines whether the detection result from the environmental sensor before the start of the print job and the detection result from the detection means after a predetermined time has elapsed since the start of the print job meet the conditions for a printing malfunction to occur, and notifies the user of the determination result.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that employs, for example, an electrophotographic method or an electrostatic recording method.

Background Art

[0002] Known image forming apparatuses include multifunction peripheral (MFP) printers, laser beam printers, facsimiles, and printing apparatuses. Dew condensation may occur in an image forming apparatus depending on the installed environment. Examples of the causes of dew condensation include the temperature drop from night to morning and the rapid temperature change inside the office when the air conditioning equipment starts operating at the beginning of business hours.

[0003] To prevent dew condensation, it is also known to provide a dehumidifying heater, which is a heat generating device for dehumidification, inside the image forming apparatus. The dehumidifying heater is powered, for example, when the main switch of the image forming apparatus is turned off at night, and warms the inside of the image forming apparatus until the main switch of the image forming apparatus is turned on the next morning. As a result, the inside of the image forming apparatus is warmed by the dehumidifying heater, the amount of saturated water vapor increases, and a state with a low relative humidity inside the machine is maintained.

[0004] In this case, when the main switch of the image forming apparatus is turned on and the power supply to the dehumidifying heater is stopped, the internal temperature of the image forming apparatus gradually decreases because the heat retention effect of the dehumidifying heater disappears. This decrease in the internal temperature of the image forming apparatus is due to the fact that the parts of the image forming apparatus where the heating effect of the dehumidifying heater does not reach are cooled from night to morning. The overall cooling of the image forming apparatus promotes the decrease in the internal temperature of the image forming apparatus.

[0005] When the main switch of the image forming apparatus is turned on, the control module inside the image forming apparatus generates heat through the flow of electricity, which suppresses the temperature drop of the image forming apparatus. Although the amount of heat generated by the control module is less than that of the dehumidifying heater, the self-heating of the control module causes the internal temperature to rise to a certain temperature over time, thereby suppressing the occurrence of condensation.

[0006] Patent Document 1 discloses an image forming apparatus equipped with an environmental sensor for measuring the ambient temperature and humidity of the installation location outside the apparatus, a temperature sensor for detecting the temperature inside the apparatus, and a dehumidifying heater for preventing condensation inside the imaging apparatus. The saturated water vapor pressure is calculated from the temperature and relative humidity outside the image forming apparatus, and the water vapor pressure at the temperature outside the image forming apparatus is calculated from the calculated saturated water vapor pressure and relative humidity. As a result, the dew point temperature at which the outside air containing the calculated water vapor condenses can also be calculated, and it is possible to determine whether condensation may occur based on the temperature inside the image forming apparatus and the water vapor pressure of the outside air flowing into the image forming apparatus.

[0007] When it is detected that the environment is approaching one where condensation may occur, power is supplied to the dehumidifying heater of the image forming apparatus to raise the temperature inside the apparatus and avoid the risk of condensation. Although saturated water vapor pressure is used in the explanation in Patent Document 1, the saturated water vapor amount is uniquely determined from the saturated water vapor pressure, so the following explanation will use the saturated water vapor amount. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-124824 [Overview of the project] [Problems that the invention aims to solve]

[0009] In image forming apparatuses using the electrophotographic method, a sheet on which a developer image has been formed on its surface using a developer such as toner is clamped and conveyed by a fixing roller pair consisting of a heating roller and a pressing roller in the fixing unit, and then fixed by heating and pressing. In such an image forming apparatus, when the sheet is heated during fixing, the moisture contained in the sheet evaporates, and the surrounding air becomes humidified as its temperature rises. This heated and humidified air may flow back into the main unit due to the inflow of outside air depending on the installation environment of the image forming apparatus (for example, air inflow from a ceiling fan, blower, air conditioner, etc.). In this case, the temperature and humidity inside the image forming apparatus may change rapidly, and condensation may occur inside the image forming apparatus. Furthermore, even if condensation does not occur, depending on the temperature and humidity inside the image forming apparatus, malfunctions such as double feeding of sheets may be more likely to occur.

[0010] Patent Document 1 describes how the image forming apparatus detects whether the environment is approaching one where condensation may occur, based on the dew point temperature calculated from the ambient temperature and relative humidity outside the machine, and the temperature inside the machine. However, if the heated and humidified air from the sheet heating process flows back into the machine, the actual dew point temperature inside the machine may deviate significantly, potentially causing condensation to occur before the condensation prevention process can be activated. Furthermore, one known method to mitigate the effects of condensation is to install an environmental heater, such as a dehumidifying heater, to prevent condensation. However, in recent years, with the increasing cost reduction of small image forming apparatuses, it may be difficult to install an environmental heater from a cost perspective.

[0011] In view of the above-mentioned problems, the primary objective of the present invention is to provide an image forming apparatus capable of predicting the occurrence of printing defects and notifying the user. [Means for solving the problem]

[0012] The image forming apparatus of the present invention comprises a heat-generating section that generates heat during printing, a detection means for detecting at least one of the temperature and humidity around the heat-generating section, a storage means for storing at least one of the detected temperature and humidity, and a control means, wherein the control means determines whether a first detection result, which is the detection result of the detection means before the start of a print job, and a second detection result, which is the detection result of the detection means after a predetermined time has elapsed since the start of the print job, satisfy the conditions for a printing defect to occur, and notifies the user of the determination result. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an image forming apparatus that can predict the occurrence of printing defects and notify the user. [Brief explanation of the drawing]

[0014] [Figure 1] A schematic cross-sectional view of the image forming apparatus according to the present invention. [Figure 2] Control block diagram of an image forming apparatus. [Figure 3] Control block diagram of the image forming unit. [Figure 4] A diagram showing a saturated water vapor content curve and an example of a condensation occurrence region. [Figure 5] Diagram illustrating the display unit. [Figure 6] A flowchart illustrating the process for determining whether or not print quality will be reduced. [Figure 7] An explanatory diagram of a screen that displays the possibility of reduced print quality. [Figure 8] A flowchart illustrating the process for determining whether or not print quality will deteriorate, and the process for notifying the user to operate in mitigation mode. [Figure 9] An explanatory diagram showing an example of the content displayed on the display unit. [Modes for carrying out the invention]

[0015] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims, and the relative arrangement of components, numerical values, etc. are not intended to limit the scope of the present invention only to those without specific description. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention. For convenience of explanation, in the embodiments, an image forming apparatus using a one-component development system will be described, but it is not intended to limit the scope of the invention only to those. Further, a plurality of features may be arbitrarily combined. In the attached drawings, the same or similar configurations are given the same reference numerals, and duplicate explanations are omitted. Also, in this specification, printing, etc. are collectively referred to as "printing".

[0016] (First Embodiment) FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to the first embodiment. The image forming apparatus 100 is provided with a sheet feeding unit 10, an image forming unit 20, a fixing unit 30, and a sheet discharging unit 40 in order from the lower part to the upper part. Further, a sheet refeeding unit 50 is provided on the right side of the image forming unit 20 and the fixing unit 30. In the sheet feeding unit 10, the sheet P stacked in the feeding cassette 11 or the manual feed tray 17 is fed to the image forming unit 20. The sheet P stored in the feeding cassette 11 is fed to the separation roller pair 13 by the rotation of the pickup roller 12. When the sheets P are double-fed, they are separated into one sheet by the separation roller pair 13 composed of a forward rotation roller and a reverse rotation roller, and are supplied to the feeding path PS1 shown by the solid line.

[0017] Next, the sheet P is conveyed by the pair of feed rollers 15 to the pair of resist rollers 16. Here, by abutting the leading edge of the sheet P against the nip of the pair of resist rollers 16 that are stopped from rotating, the skew of the sheet P is corrected. When feeding the sheet P from the manual tray 17, the sheet is separated into single sheets by the supply roller 18a and the separation pad 18b. Then, it is supplied to the pair of feed rollers 15 by the pair of supply rollers 19 and conveyed to the pair of resist rollers 16, thereby correcting the skew of the sheet P. The sheet with the skew corrected is conveyed to the image forming unit 20 by the pair of resist rollers 16 that rotate at a predetermined timing.

[0018] In the image forming unit 20, the surface of the photosensitive drum 21 is uniformly charged by the charging roller 22. When laser light corresponding to the image information is irradiated from the laser unit 23, the charge that was charged by the charging roller 22 is removed from the portion of the photosensitive drum 21 irradiated with the laser light, and an electrostatic latent image corresponding to the image information is formed. The electrostatic latent image formed here is visualized as a developer image by attaching the developer by the developing roller 24 of the developing device. This developer image is conveyed to the transfer nip portion N1 by the rotation of the photosensitive drum 21. The sheet P is conveyed from the pair of resist rollers 16 to the transfer nip portion N1 at this timing.

[0019] The conveyed sheet P is sandwiched and conveyed between the photosensitive drum 21 and the transfer roller 25 at the transfer nip portion N1. At this time, the developer image formed on the photosensitive drum 21 is transferred to the sheet P by applying a bias voltage from the transfer roller 25. The laser light irradiated from the laser unit 23 is controlled based on the image data transmitted from the host PC1.

[0020] Next, the sheet P on which the developer image has been formed is transported to the fixing unit 30. The fixing unit 30 consists of a heat source such as a halogen lamp (not shown), a fixing roller 31, and a pressure roller 32. The fixing roller 31 is made of a material such as aluminum and is heated to a predetermined temperature by the heat source. The pressure roller 32 is set to contact the fixing roller 31 and apply a predetermined pressure, forming a fixing nip section N2. The sheet P on which the developer image has been formed is fed into the fixing nip section N2 and is held and transported between the fixing roller 31 and the pressure roller 32. At this time, the heating and pressurizing fixes the developer image onto the sheet P. Note that the fixing unit 30 is not limited to a heating roller method in which the fixing roller 31 heats the sheet; for example, an on-demand fixing method may also be used. In this case, the fixing nip section N2 is formed by applying pressure from a heat source such as the ceramic heater 33 shown in Figure 3 (described later) via an edgeless film using the pressure roller 32, and heating and pressurizing are performed while the sheet P is held and transported in the nip section N2. The sheet P, on which the developer image has been fixed, is transported to the sheet discharge section 40 and discharged into the discharge tray 42 by the discharge roller pair 41.

[0021] When forming images on both sides of sheet P, as sheet P with the image formed on the first side is being transported by the discharge roller pair 41, the discharge roller pair 41 is temporarily stopped before the rear end of sheet P passes through the discharge roller pair 41, and then the discharge roller pair 41 is rotated in the reverse direction. This causes sheet P to be inverted and transported to the sheet refeeding section 50. Sheet P transported to the sheet refeeding section 50 is transported along the refeeding path PS2 shown by the dashed line by the refeeding roller pair 51a and 51b, and then transported to the resist roller pair 16 by the refeeding roller pair 51c. After the sheet P's skew is corrected by the resist roller pair 16, the back side is transported to the transfer nip section N1, forming a developer image on the second side of sheet P. After that, the developer image is fixed to sheet P by transporting it through the fixing nip section N2, similar to when an image was formed on the front side, and sheet P with images formed on both sides is discharged to the discharge tray 42 by the discharge roller pair 41.

[0022] Inside the image forming apparatus 100, an environmental sensor S is installed as a detection means for detecting at least one of the temperature and humidity around or near the heat-generating part that generates heat during printing. In the first embodiment, the heat-generating part corresponds to the heat source of the fixing unit 30, and the environmental sensor S is capable of detecting the temperature and humidity (ambient temperature and ambient humidity) around the fixing unit 30 and is positioned to detect the temperature and humidity around or near the fixing unit 30. For this purpose, the environmental sensor S is installed in the same space as the charging roller 22, developing roller 24, photosensitive drum 21, and laser unit 23, without shielding, and is capable of detecting temperature and humidity as electrical signals. Furthermore, considering the influence of outside air inflow, the environmental sensor S is installed downstream of arrow A, through which the heated and humidified air generated during the fixing of the sheet P passes, so that it can measure changes in the temperature and humidity of the atmosphere around the fixing unit 30.

[0023] When high-temperature and high-humidity air flows back into the image forming apparatus 100 from the sheet discharge section or other parts due to the inflow of outside air, the backflowing air passes through the air passage indicated by arrow A in Figure 1. As a result, condensation may form on the charging roller 22, developing roller 24, photosensitive drum 21, laser unit 23, etc. of the image forming section 20, potentially causing various image problems such as a decrease in the density of the output image, development and transfer defects.

[0024] Thermistors are commonly known as means for detecting temperature, and capacitive sensors are commonly known as means for detecting humidity. In the first embodiment, a composite sensor combining these two was used. Furthermore, since humidity is uniquely determined by temperature and water vapor content, detecting humidity is essentially equivalent to detecting water vapor content. In the following explanation, we will use water vapor content.

[0025] Figure 2 is a control block diagram of the image forming system shown in Figure 1. In Figure 2, the CPU 101 functions as a control means. The CPU 101 includes RAM 102, which is used for storing input data and as a working memory area, and ROM 103, which stores programs such as control procedures. The CPU 101 is connected to the host PC 1 via an external interface 2 and performs functions such as receiving image data and transmitting device status. The CPU 101 is connected to the image signal processing unit 110, the image reading device control unit 120, the image forming device control unit 130, and the display unit 140, respectively, which process image signals from the host PC 1. The image forming device control unit 130 forms an image on a sheet according to the image signal sent from the image signal processing unit 110. The display unit 140 displays the image forming device settings screen and a display screen for messages to the user, and also functions as a unit for receiving user operations.

[0026] Figure 3 is a block diagram of the image forming apparatus control unit 130 in Figure 2. In Figure 3, the image forming apparatus control unit 130 includes a CPU 121 as a control means, which has a RAM 122 used for storing input data and as a working memory area, and a ROM 123 that stores programs such as control procedures. A voltage control unit U1 for applying voltage to the charging roller 22, developing roller 24, transfer roller 25, and ceramic heater 33 as a heat source is connected to the CPU 121 via an I / O port 124. A laser unit 23 for exposing the surface of the photosensitive drum 21 in Figure 1, a common drive motor driver D1, and a fan motor driver D2 are also connected to the CPU 121.

[0027] The common drive motor driver D1 controls the operation of the common drive motor M1, which acts as a drive source for rotating the photosensitive drum 21, developing roller 24, and transfer roller 25. The fan motor driver D2 controls the operation of the fan motor M2, which drives the cooling fan 60 that cools the fixing unit 30 and the sheet P in Figure 1. An environmental sensor S is connected to the CPU 121, and the temperature Tin-s around the image forming unit 20 detected by the environmental sensor S is stored in the RAM 122. In addition, the saturated water vapor amount curve shown in Figure 4 is stored in advance in the RAM 102 (or any storage unit such as ROM 103). The CPU 121 uses this saturated water vapor amount curve to determine the saturated water vapor amount Win-s for the temperature Tin-s and stores it in the RAM 122.

[0028] Figure 5 is a detailed view of the display unit 140. The display unit 140 includes a start key 142 for starting the image formation operation and a stop key 143 for interrupting the image formation operation. Furthermore, it includes numeric keypads 144 to 153 for entering numbers, which are used by the user to set the number of copies to print, etc. The display unit 140 also includes a touch panel 141, which is a display unit for displaying setting information related to image formation, error screens, and for the user to perform touch input.

[0029] Figure 6 is a flowchart illustrating an example of a process in which the display content of the display unit 140 is changed based on changes in temperature and water vapor content after a predetermined time has elapsed since the power of the image forming apparatus 100 was turned ON and a print job was received. A print job is information that instructs a series of image forming operations on one or more sheets, accompanied by an instruction to start the image forming operation. After the power of the image forming apparatus is turned ON (S101), when a print job is sent from the host PC 1 to the image forming apparatus 100 as a print command, the CPU 121 rotates the common drive motor via the common drive motor driver D1. The CPU 121 also applies voltage to the ceramic heater 33 via the voltage control unit U1 to heat it and start the operation of the fuser unit 30 (S102). Unless otherwise specified, each process in Figure 6 is executed by the CPU 121.

[0030] When the CPU 121 receives a print job, it obtains the temperature Tin-s inside the image forming unit 20 from the environmental sensor S before starting the print job. Alternatively, the temperature Tin-s inside the image forming unit 20 may be obtained in advance from the environmental sensor S at any time after the power of the image forming apparatus is turned on. The CPU 121 obtains the saturated water vapor amount Win-s at temperature Tin-s from the obtained temperature Tin-s and the saturated water vapor amount curve data stored in RAM 102 in advance (S103).

[0031] Furthermore, the CPU 121 stores Tin-s and Win-s in RAM 102 (S104) and executes the print operation (S105). The CPU 121 obtains the temperature Tin-t and water vapor amount Win-t inside the image forming unit 20 after a predetermined time has elapsed (after t minutes) from the start of the print job (S106), and determines whether these meet predetermined conditions. Note that the temperature Tin-t is detected by the environmental sensor S, and the water vapor amount is calculated from the temperature Tin-t and the humidity detected by the environmental sensor S. The CPU 121 compares the temperature Tin-t and water vapor amount Win-t with the Tin-s and Win-s stored in RAM 102 (S107) and determines whether the condition "Tin-t > Tin-s and Win-t > Win-s" is met.

[0032] The "predetermined conditions" correspond to the "conditions under which printing defects occur," and in the first embodiment, the "predetermined conditions" are defined as the conditions under which condensation may occur in the image forming apparatus 100. This is because condensation can cause printing defects. The conditions under which condensation occurs due to the inflow of outside air will be explained using the saturated water vapor amount curve in Figure 4. As shown in Figure 4, when the temperature Tin-s inside the image forming section 20 is 25°C, the saturated water vapor amount Win-s is 23 g / m³. 3When a print job is received and the printing operation is performed, water vapor is generated when toner is fixed to the surface of the printed material. In normal printing operations, neither the temperature nor the amount of water vapor inside the image forming unit 20 rises. However, if warm, humid air is pushed back due to the inflow of outside air, both the temperature and the amount of water vapor inside the image forming apparatus 100 may rise after a predetermined time (for example, t=5 (minutes) after the start of the print job). In this case, parts around the image forming unit 20 that have not yet warmed up reach their dew point temperature and condensation occurs.

[0033] In the saturated water vapor amount curve in Figure 4, when the temperature Tin-s is 25°C, the saturated water vapor amount Win-s at 25°C is 23 g / m³. 3 Therefore, if the temperature Tin-t and water vapor amount Win-t inside the image forming unit 20 after a predetermined time from the start of the print job (for example, after t=5 minutes) are within the shaded area shown in the upper right of Figure 4, the components inside the image forming unit 20 will reach the dew point temperature and condensation will occur. Accordingly, if the determination result is "Tin-t > Tin-s and Win-t > Win-s" (within the shaded area in Figure 4) (S108:Y), the CPU 121 proceeds to S109. In this case, it is indicated that Tin-t is higher than Tin-s and Win-t is greater than Win-s. In S109, the CPU 121 notifies the user that there is a possibility of problems occurring due to condensation caused by the inflow of outside air. In the example in Figure 6, in order to alert the user, the display unit 140 displays a message that the print quality may deteriorate (S109) and also displays a message recommending that the orientation or position of the main unit be changed (S110).

[0034] If the judgment result is not "Tin-t > Tin-s and Win-t > Win-s" (outside the shaded area in Figure 4, S108:N), the CPU 121 determines that no condensation-related problems will occur due to the influx of outside air. As a result, it determines that a warning display to the user is unnecessary, and the flowchart in Figure 6 is terminated.

[0035] Examples of notifications to users indicating the possibility of printing problems include displaying a warning that print quality may be reduced, or issuing a warning about reduced print quality. Figure 7 shows an explanatory diagram of a screen that indicates to users the possibility of problems caused by condensation. In this example, the message indicating that print quality may be reduced reads, "Print quality may be reduced due to the influence of outside air." It also displays information on how to avoid printing problems. As a recommended action, for example, it is possible to display a message recommending that the orientation or position of the image forming apparatus be changed. Therefore, in Figure 7, the message reads, "We recommend changing the orientation and position of the main unit."

[0036] Furthermore, Figure 7 displays the user's options, including the message, "Do you want to turn off the power and change the orientation and position?", along with "OK" and "Continue Printing" buttons. If the user wishes to cancel printing to avoid a decrease in print quality, they press the "OK" button. In this case, the user can prevent a decrease in print quality by turning off the power to the image forming apparatus for safety and changing the orientation and position of the image forming apparatus. Alternatively, if the user decides that a decrease in print quality is acceptable, they can press the "Continue Printing" button to continue printing. If "OK" is pressed, the user will turn off the power, so the CPU 121 is configured to display a message at startup to confirm whether the user has taken steps to prevent printing problems at the next startup. In the first embodiment, the message "Have you changed the orientation or position of the image forming apparatus?" is displayed to confirm the installation status of the main unit.

[0037] As described above, in the image forming apparatus of the first embodiment, based on the detection results of temperature and water vapor amount inside the image forming apparatus 100, it is possible to notify the user of the possibility of a decrease in print quality before a printing problem occurs and to warn them. Printing problems include, for example, image defects and a decrease in print quality. Therefore, the user can recognize problems such as a decrease in print quality caused by condensation due to the inflow of outside air. In addition, by displaying specific countermeasures to prevent printing problems, the user can take the necessary actions themselves.

[0038] (Second Embodiment) In the second embodiment, when the CPU 121 determines that a problem caused by condensation due to the inflow of outside air is occurring, it displays this fact on the display unit 140 and notifies the user that it will operate in countermeasure mode, thereby preventing the problem caused by condensation due to the inflow of outside air. In countermeasure mode, the CPU 121 executes the print job under operating conditions that suppress printing defects. Figure 8 shows a flowchart representing the process of determining whether or not the print quality will deteriorate and the process of notifying the user of operation in countermeasure mode. Note that in Figure 8, the processes from S201 to S209 are the same as S101 to S109 in the flowchart of Figure 6 in the first embodiment, so the explanation is omitted.

[0039] After executing S209, the CPU 121 displays on the display unit 140 that it is operating the image forming apparatus 100 in countermeasure mode (S210), and then executes the countermeasure mode (S211). An example of the display content in S210 is shown in Figure 9. As shown in the figure, in the second embodiment, the user is shown the message "Printing in countermeasure mode to prevent a decrease in print quality." In countermeasure mode, as an operating condition to suppress printing defects, the print job is executed with operating conditions that reduce the amount of water vapor generated from the printed material. In this case, the CPU 121 operates the image forming apparatus to reduce the amount of water vapor generated from the printed material per unit time, so that the amount of water vapor in the air does not reach the saturation water vapor amount. Specifically, this is done by increasing the distance between sheets of paper in the printed material, or by reducing the printing speed. As a result, although the productivity of the printed material will decrease, it will be possible to ensure print quality.

[0040] The CPU 121 obtains the temperature Tin-t' and water vapor amount Win-t' after a predetermined time (t' minutes) has elapsed since executing the countermeasure mode, and compares them with Tin-s and Win-s stored in RAM 102 (S212). If Tin-t' > Tin-s and Win-t' > Win-s (S213:N), the temperature Tin-t' and water vapor amount Win-t' are within the shaded area shown in the upper right of Figure 4. Therefore, the CPU 121 returns to step S211 and continues executing the countermeasure mode.

[0041] On the other hand, if Tin-t' ≤ Tin-s or Win-t' ≤ Win-s (S213:Y), the temperature Tin-t' and water vapor amount Win-t' are outside the shaded area shown in the upper right of Figure 4. Therefore, in this case, the CPU 121 cancels operation in countermeasure mode and the display of operation in countermeasure mode on the display unit 140 (S214), and terminates processing.

[0042] In the image forming apparatus described in the second embodiment, based on the detection results of the temperature and water vapor amount inside the image forming apparatus 100, it is possible to operate in condensation prevention mode before image defects occur, thereby preventing problems caused by condensation due to the inflow of outside air. Furthermore, by displaying on the display unit 140 that the apparatus is operating in prevention mode, it is possible to inform the user that the apparatus is operating in prevention mode.

[0043] In the first and second embodiments, under the predetermined conditions described above, the temperature Tin-s and water vapor amount Win-s are compared with the temperature Tin-t and water vapor amount Win-t to determine whether the conditions for condensation to occur in the image forming apparatus 100 are met. However, the predetermined conditions are not limited to this example. For example, if at least one of the temperature Tin-t or the water vapor amount Win-t changes rapidly, it may affect the print quality or cause problems such as difficulty in separating sheets and increased likelihood of double feeding.

[0044] Therefore, conditions under which printing problems may occur, including a decrease in print quality and double feeding of sheets, may be stored in ROM 103 or RAM 102 in advance, based on at least one of temperature and water vapor amount. In this case, the predetermined conditions described above will be based on the change in at least one of temperature and water vapor amount between the start of the print job and after time t (minutes) has elapsed. For example, the predetermined conditions can be based on the numerical values ​​and change amounts of temperature Tin-s and temperature Tin-t, or water vapor amount Win-s and water vapor amount Win-t. Thus, any conditions can be used as predetermined conditions, as long as it can be determined that printing problems may occur based on at least two of temperature Tin-s, water vapor amount Win-s, temperature Tin-t, and water vapor amount Win-t.

[0045] Furthermore, in the first and second embodiments, a display is shown on the display unit 140 to indicate the possibility of printing problems, but the notification is not limited to this, and may also be given by voice, warning sound, etc.

[0046] Furthermore, while the environmental sensor S is positioned to detect the temperature and humidity around or near the fixing unit 30, it is not limited to this position; it can also be positioned to detect the temperature and humidity around a heat-generating element that may cause printing problems. In this case as well, it is preferable to install the environmental sensor S downstream of the heated and humidified airflow so as to measure changes in temperature and humidity, taking into account the influence of outside air inflow.

Claims

1. The heating element that generates heat during printing, A detection means for detecting at least one of the temperature and humidity around the heat-generating part, A storage means for storing at least one of the detected temperature and humidity, It has control means, The control means is characterized by determining whether the first detection result, which is the detection result of the detection means before the start of the print job, and the second detection result, which is the detection result of the detection means after a predetermined time has elapsed since the start of the print job, satisfy the conditions for a printing malfunction to occur, and notifying the user of the determination result. Image forming apparatus.

2. The detection means is characterized by detecting both the temperature and humidity around the heat-generating part. The image forming apparatus according to claim 1.

3. The control means is characterized by determining a first saturated water vapor amount, which is the saturated water vapor amount before the start of the print job, from the first detection result, and determining a second saturated water vapor amount, which is the saturated water vapor amount after a predetermined time has elapsed since the start of the print job, from the second detection result. The image forming apparatus according to claim 2.

4. The conditions under which the printing malfunction occurs include the conditions that the second saturated water vapor amount is greater than the first saturated water vapor amount, and that the temperature detected by the detection means after a predetermined time has elapsed since the start of the printing job is higher than the temperature detected by the detection means before the start of the printing job. The image forming apparatus according to claim 3.

5. It further has a means of display, The control means is characterized by causing the display means to display a screen indicating the possibility of printing problems occurring. The image forming apparatus according to claim 1.

6. The control means is characterized by notifying the user of measures to avoid printing problems. The image forming apparatus according to claim 1.

7. It further has a means of display, The control means is characterized by causing the display means to display a screen indicating measures to avoid the occurrence of the printing malfunction. The image forming apparatus according to claim 6.

8. The measures taken to avoid the occurrence of the aforementioned printing defects include turning off the power to the image forming apparatus and changing the orientation or position of the image forming apparatus. The image forming apparatus according to claim 7.

9. The control means is characterized in that, when a measure to avoid the occurrence of the printing malfunction is displayed, the image forming apparatus is configured to display a message at the next startup of the image forming apparatus to confirm whether the user has taken the measure to avoid the printing malfunction. The image forming apparatus according to claim 8.

10. The control means is characterized in that, when the conditions for the occurrence of the printing malfunction are met in the determination result, it executes the print job with operating conditions to suppress the printing malfunction. The image forming apparatus according to claim 1.

11. The control means is characterized by determining whether the third detection result and the first detection result, which are the detection results of the detection means when the print job is executed under operating conditions for suppressing the printing defects, satisfy the conditions for the occurrence of the printing defects. The image forming apparatus according to claim 10.

12. The control means repeatedly determines whether the third detection result and the first detection result satisfy the conditions for the occurrence of the printing malfunction, and when the conditions are no longer satisfied, it releases the operating conditions for suppressing the printing malfunction. The image forming apparatus according to claim 11.

13. The control means is characterized in that, under operating conditions to suppress printing defects, it either increases the distance between sheets of paper in the printed material or reduces the printing speed when executing the print job. The image forming apparatus according to claim 12.

14. It further has a means of display, The control means is characterized by displaying a screen on the display means indicating that the print job is being executed under operating conditions that suppress printing malfunctions. The image forming apparatus according to claim 10.

Images