JP6642469B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to a continuous printing technique for continuously printing on a plurality of recording sheets.

  When the temperature inside the image forming apparatus becomes high, the deterioration or melting of the developer occurs, and the image forming quality may be deteriorated. In addition, various components such as a stepping motor and gears may deteriorate rapidly, and the image forming operation may be unstable. In particular, in continuous printing in which printing is continuously performed on a plurality of recording sheets, the temperature inside the image forming apparatus tends to become high. On the other hand, Japanese Patent Application Laid-Open No. H11-133,086 discloses a technique for changing the printing speed (switching from full speed to half speed) based on the current temperature and the number of unprinted recording sheets during continuous printing. Have been. Patent Document 2 below includes an in-machine temperature sensor provided at a predetermined position in an image forming apparatus, and an environmental temperature sensor provided at an installation position of the image forming apparatus. Discloses a technique for estimating a current temperature at a position different from a position where an in-machine temperature sensor is installed, based on a temperature detected by a temperature sensor and a temperature detected by an environmental temperature sensor. In the technique disclosed in Patent Literature 2, the printing speed is changed based on the estimated temperature at the present time.

JP 2013-167853 A JP 2007-322539 A

  However, the techniques disclosed in Patent Document 1 and Patent Document 2 are techniques for changing the printing speed based on the current temperature. For this reason, when the temperature in the image forming apparatus rises rapidly, the printing speed cannot be changed before the temperature in the image forming apparatus becomes high. In this case, the printing speed is changed after the temperature inside the image forming apparatus becomes high. However, in this case, there is a possibility that the developer is deteriorated or melted, and the image forming quality is reduced. In addition, various components such as a stepping motor and gears may deteriorate rapidly, and the image forming operation may be unstable.

  The present invention has been made in view of the above circumstances, and even in a situation where the temperature inside the image forming apparatus may suddenly increase, it is possible to prevent the temperature inside the image forming apparatus from becoming high during continuous printing. It is an object of the present invention to more reliably prevent the occurrence of a situation in which image forming quality is degraded or an image forming operation becomes unstable.

An image forming apparatus according to one aspect of the present invention controls a printing unit, a receiving unit that receives a printing instruction, and a printing operation performed by the printing unit, and performs continuous printing of the number of prints indicated by the printing instruction in advance. An operation control unit for causing the printing unit to perform the printing at a printing speed, a temperature sensor provided in the image forming apparatus, and a signal indicating a temperature detected by the temperature sensor during continuous printing by the printing unit. Is acquired at every predetermined time , using the temperature detected by the temperature sensor at the time of acquiring the signal, and the temperature detected by the temperature sensor before the time of acquiring the signal. Calculating an approximate curve indicating a predicted value of the temperature in the image forming apparatus after the time when the signal is obtained, and calculating the approximate curve of the number of prints indicated by the print instruction. And unprinted print sheets that are not printed by Oite the printing unit, and the based on the printing speed that is determined in advance, the predicted value calculation unit repeats the processing of the continuous printing is calculated printing completion time completed The operation control unit, the predictive value of the temperature indicated by the approximate curve , every time the predicted value calculating unit calculates the approximate curve and the print completion time, until the print completion time The process of determining whether or not the temperature is equal to or more than a predetermined threshold is repeated, and in the process, when the predicted value of the temperature is equal to or more than a predetermined threshold, the predetermined printing speed is changed. The image forming apparatus is configured to perform the continuous printing with a delay by a predetermined value.

  According to the present invention, even in a situation where the temperature inside the image forming apparatus may suddenly rise, the inside of the image forming apparatus is more reliably prevented from becoming hot during continuous printing, and the image forming quality is reduced. It is possible to avoid a situation where the image forming operation is lowered or the image forming operation becomes unstable.

1 is a front sectional view illustrating a structure of an image forming apparatus according to an embodiment of the present disclosure. FIG. 1 is a block diagram schematically illustrating a main internal configuration of an image forming apparatus according to an embodiment of the present disclosure. 6 is a flowchart illustrating a flow of an operation of the image forming apparatus according to the embodiment of the present disclosure. (A) is a figure which shows an example of the temperature detected by the 1st temperature sensor until the present, and (B) is a figure which shows an example of the temperature change after the present calculated by the temperature displacement calculation part. . FIG. 7 is a diagram illustrating an example of a temperature change when continuous printing is performed at a changed printing speed. It is a figure showing an example of an operation mode selection screen.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is, for example, a multifunction peripheral having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 is configured by including an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, a document reading unit 5, and the like in a device main body 11 (device main body). ing.

  When the image forming apparatus 1 performs a document reading operation, the document reading unit 5 optically reads an image of a document fed by the document feeding unit 6 or a document placed on the document loading glass 161. Generate data. The image data generated by the document reading unit 5 is stored in a built-in HDD or a computer connected to a network.

  When the image forming apparatus 1 performs an image forming operation, the image forming unit 12 supplies the image data from the sheet feeding unit 14 based on the image data generated by the document reading operation or the image data stored in the built-in HDD. A toner image is formed on a recording paper P as a recording medium fed by a paper roller 141. The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 12 include a photosensitive drum 121 (image carrier), a charging device 123, an exposure device 124, a developing device 122, and a primary transfer roller 126. Are provided.

  Each of the developing devices 122 of the image forming units 12M, 12C, 12Y, and 12Bk contains toner for developing an electrostatic latent image. The developing device 122 supplies the toner to the surface of the photosensitive drum 121 on which the charging by the charging device 123 and the exposure by the exposure device 124 are completed.

  When performing color printing, the image forming unit 12M for magenta, the image forming unit 12C for cyan, the image forming unit 12Y for yellow, and the image forming unit 12Bk for black of the image forming unit 12 respectively transmit image data. A toner image is formed on the photosensitive drum 121 by the steps of charging, exposing, and developing based on the image composed of the respective color components, and the primary transfer roller 126 applies the toner image to the driving roller 125A and the driven roller 125B. The image is transferred onto an intermediate transfer belt 125 stretched over the intermediate transfer belt 125.

  The intermediate transfer belt 125 has an image bearing surface on which a toner image is transferred on its outer peripheral surface, and is driven by a driving roller 125A in a state of being in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 runs endlessly between a driving roller 125A and a driven roller 125B in synchronization with each photosensitive drum 121.

  The toner images of each color transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 by adjusting the transfer timing to form a color toner image. The secondary transfer roller 210 transfers the color toner image formed on the surface of the intermediate transfer belt 125 from the paper supply unit 14 to a proper position on the conveyance path 190 at a nip portion N between the intermediate transfer belt 125 and the drive roller 125A. Is transferred onto the recording paper P conveyed in the conveyance path 190 by the conveyance roller pair 191 provided in the printer. Thereafter, the fixing unit 13 fixes the toner image on the recording paper P to the recording paper P by thermocompression using a fixing roller 133 having a heating roller and a pressure roller. The recording paper P on which the color image has been formed after the fixing process is discharged to the discharge tray 151.

  Here, a plurality of temperature sensors including a thermistor such as a first temperature sensor 130, a second temperature sensor 140, and a third temperature sensor 150 are provided in the apparatus main body 11 of the image forming apparatus 1. I have. The first temperature sensors 130 are arranged one by one in or near the developing devices 122 for each of the colors magenta, cyan, yellow, and black, and detect the temperature inside the developing devices 122 for each color. The second temperature sensors 140 are arranged one by one in or near the charging device 123 for each of the colors magenta, cyan, yellow and black, and detect the temperature inside the charging device 123 for each color. The third temperature sensor 150 is disposed near the fixing roller 133 in the fixing unit 13 and detects the temperature of the fixing roller 133.

  Signals indicating the temperatures detected by these temperature sensors are input to a control unit 10 (see FIG. 2), which will be described later, and used by the control unit 10 to control the operation of each mechanism of the image forming apparatus 1. Specifically, the second temperature sensor 140 that detects the temperature inside the charging device 123 for each color is intended to detect the environmental state of the charging roller of the charging device 123. Since the resistance of the charging roller changes according to the temperature, the operation control unit 101 of the control unit 10 adjusts the charging voltage applied to the charging roller based on the temperature detected by the second temperature sensor 140. Further, the third temperature sensor 150 for detecting the temperature of the fixing roller 133 is intended to monitor the fixing temperature. The operation control unit 101 of the control unit 10 adjusts the time for heating the heating roller of the fixing roller 133 based on the temperature detected by the third temperature sensor 150.

  The first temperature sensor 130 that detects the temperature in the developing device 122 for each color is intended to detect the environmental state in the storage unit that stores the developer of the developing device 122. When the temperature of the developer becomes high, the developer deteriorates or melts. Although the details will be described later, the temperature detected by the first temperature sensor 130 is used for control by the control unit 10 for preventing the deterioration and melting of the developer.

  As described above, the first temperature sensor 130 and the second temperature sensor 140 are provided for each developing device 122 of each color and each charging device 123 of each color. This is based on the fact that the temperature is different between a position near and far from the fixing roller 133 serving as a heat source, and that the amount of the supplied developer varies depending on the type of image.

  Next, the electrical configuration of the image forming apparatus 1 will be described. FIG. 2 is a functional block diagram schematically showing a main internal configuration of the image forming apparatus 1.

  The image forming apparatus 1 includes an operation unit 47, an image memory 32, and an HDD in addition to the image forming unit 12, the fixing unit 13, the first temperature sensor 130, the second temperature sensor 140, and the third temperature sensor 150 described above. (Hard Disk Drive) 92, a control unit 10, a drive unit 17, and the like.

  The operation unit 47 includes a touch panel unit and an operation key unit that receive instructions from a user regarding various operations and processes that can be executed by the image forming apparatus 1. The touch panel unit includes a display unit 473 such as an LCD (Liquid Crystal Display) provided with a touch panel.

  The image memory 32 is an area for temporarily storing image data obtained by reading by the document reading unit 5 and temporarily storing data to be image-formed by the image forming unit 12.

  The HDD 92 is a large-capacity storage device that stores a document image and the like read by the document reading unit 5.

  The control unit 10 includes a processor, a random access memory (RAM), a read only memory (ROM), and a dedicated hardware circuit. The processor is, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like. The control unit 10 functions as a control unit 100, an operation control unit 101, a predicted value calculation unit 102, a display control unit 103, and a reception unit 104 by the operation of the processor according to the control program installed in the HDD 92. However, the control unit 100 and the like may be configured by hardware circuits without depending on the operation of the control unit 10 according to the control program.

  The control unit 100 controls the overall control of the image forming apparatus 1.

  The operation control unit 101 is connected to a printing unit including an image forming unit 12, a fixing unit 13, and a driving unit 17 including a plurality of driving units 171 to 177 including a stepping motor and gears. It has a function to control the printing operation.

  The upper limit of the printing speed of the printing unit (the upper limit of the number of printable sheets per unit time) is the performance limit of each mechanism constituting the printing unit of the image forming apparatus 1 (the developing performance of the developing device 122, the fixing of the fixing unit 13). Performance, the transport performance of the transport roller pair 191). However, as the printing speed increases, the speed at which the mechanisms constituting the printing unit deteriorate due to wear and the like increases. In addition, as the printing speed increases, the power and operation noise required to operate each mechanism increase. Therefore, when the product of the image forming apparatus 1 is shipped, it is set not to operate at the upper limit speed but to operate at a print speed lower than the upper limit speed in consideration of the product life, power consumption, and the like. This setting is stored in an area in the HDD 92 that cannot be accessed by ordinary users. The operation control unit 101 reads the settings stored in the HDD 92 and controls the printing units such as the image forming unit 12, the fixing unit 13, and the driving unit 17 so that printing is performed at the printing speed indicated by the settings.

  The display control unit 103 has a function of controlling a display operation by the display unit 473. For example, the display control unit 103 causes the display unit 473 to display a predetermined print instruction reception screen.

  The reception unit 104 has a function of receiving a user instruction input using the touch panel unit or the operation key unit of the operation unit 47. The receiving unit 104 receives a print instruction including various settings such as the number of prints, image data to be printed, and the size of recording paper, based on a user instruction performed on a print instruction reception screen displayed on the display unit 473. .

  The predicted value calculation unit 102 is a temperature detecting unit that detects the temperature detected by the first temperature sensor 130 among the plurality of sensors provided in the apparatus main body 11 of the image forming apparatus 1, that is, the developing devices for the respective colors of magenta, cyan, yellow, and black. It has a function of calculating a predicted value (temperature change) of the temperature in and after 122 in the current time. The predicted value calculation unit 102 acquires a signal indicating the temperature detected by the first temperature sensor 130 provided for each developing device 122 of each color at predetermined time intervals. Then, the predicted value calculation unit 102 calculates a predicted value of the temperature after the present time (at the time when the signal is obtained) based on the change in the temperature indicated by the obtained signal. Details of the processing will be described later.

  The predicted value calculation unit 102 is a temperature sensor other than the first temperature sensor 130 among the plurality of sensors provided in the apparatus main body 11 of the image forming apparatus 1, that is, the second temperature sensor 140 and the third temperature sensor. For the temperature detected by 150, the above-described process of calculating the predicted value of the temperature is not performed.

  The operation control unit 101 determines whether to decrease the printing speed of the printing unit based on the predicted value of the temperature after the current calculated by the predicted value calculation unit 102 described above. Specifically, it is determined whether or not the predicted value of the temperature is equal to or greater than a predetermined threshold value by the time when the continuous printing of the number of printed sheets is completed, and when the temperature is equal to or greater than the predetermined threshold value, The printing speed of the printing unit is reduced to perform continuous printing.

  The printing speed is changed by the operation control unit 101 causing the printing unit to change the process speed during the printing operation. Specifically, the operation control unit 101 controls the photosensitive drum drive unit 175 to change the peripheral speed of the photosensitive drum 121, and controls the transport roller drive unit 172 to change the transport speed of the recording paper P. By doing so, the process speed during the printing operation is changed.

  The operation control unit 101 does not change the process speed during the printing operation, but controls the paper feed roller driving unit 171 and the transport roller driving unit 172, etc., so that the printing unit prints the recording paper P during the continuous printing operation. The printing speed may be changed by changing the paper passing interval of the printing.

  With reference to the flowchart shown in FIG. 3, the details of the processing performed by each of the above components will be further described.

  If a print job (print instruction) for continuous printing is input by the user using the operation unit 47 or the like and the input print job is received by the receiving unit 104 (YES in step S10), the operation control unit 101 executes The printing unit such as the forming unit 12, the fixing unit 13, and the driving unit 17 is controlled to execute the print job at the printing speed indicated by the setting stored in the HDD 92 (step S11).

  The predicted value calculation unit 102 acquires a signal indicating the temperature detected by the first temperature sensor 130 at predetermined time intervals while the printing unit performs continuous printing in the process of step S11 (step S12, step S12). S13). The predicted value calculation unit 102 causes the HDD 92 to store the temperature acquired in step S13.

  After the process of step S13, the predicted value calculation unit 102 performs a process of calculating a predicted value of the temperature after the present (step S14). In this process, a temperature change after the present is simulated based on the following three elements (1) to (3).

(1) The temperature acquired in the process of step S13, that is, the temperature detected by the first temperature sensor 130 at the current time.
(2) A change in the temperature stored in the HDD 92, that is, a change in the temperature detected by the first temperature sensor 130 before the current time.
(3) Among the number of prints indicated by the print instruction accepted in the process of step S10, the number of unprinted prints that have not been printed by the printing unit.

  In the example shown in FIG. 4A, D1 is the temperature detected by the first temperature sensor 130 at the current time, and D2 is the temperature detected by the first temperature sensor 130 before the current time. The predicted value calculation unit 102 calculates a change (gradient) in temperature per unit time from the temperature indicated by D2. From this temperature change and the current temperature indicated by D1, an approximate curve of the predicted value of the temperature indicated by L1 in FIG. 4B is calculated.

  Further, the predicted value calculation unit 102 calculates the time to complete printing when continuous printing is performed at the current printing speed from information on the number of unprinted prints. From the time required until the printing is completed and the approximate curve of the predicted value of the temperature, the temperature that increases until the printing is completed is calculated. In the example shown in FIG. 4B, it is predicted that the temperature detected by the first temperature sensor 130 will be equal to or higher than a predetermined threshold temperature A by the time T1 when printing is completed.

  Note that the predicted value calculation unit 102 performs the above-described processing for each of the plurality of first temperature sensors 130 provided for each developing device 122 for each color, and calculates a predicted value of the temperature after the present.

  Returning to FIG. 3, when the predicted value of the temperature is equal to or higher than the predetermined threshold temperature by the time when the continuous printing is completed (YES in step S <b> 15), operation control unit 101 decreases the printing speed by the printing unit. Then, in the process of step S11, the printing unit is caused to perform continuous printing at the changed printing speed. On the other hand, when the predicted value of the temperature is not the temperature of the predetermined threshold value by the time when the continuous printing is completed (NO in step S15), the operation control unit 101 does not change the printing speed of the printing unit (step S16). In the process of step S11, the printing unit is caused to perform continuous printing at the same printing speed. The operation control unit 101 and the predicted value calculation unit 102 perform the processing of steps S11 to S17 until the continuous printing of the number of prints indicated by the print instruction received in the processing of step S10 is completed.

  In the process of step S17, the operation control unit 101 reduces the printing speed of the printing unit. At this time, the operation control unit 101 decreases the printing speed by a predetermined speed. For example, when the normal printing speed (printing speed set at the time of product shipment) is 60 sheets / minute, the operation control unit 101 reduces the printing speed by the predetermined speed (5 sheets / minute) and changes the printing speed. The subsequent printing speed is 55 sheets / min. When the process of step S17 is performed again, the operation control unit 101 further reduces the printing speed from the changed printing speed of 55 sheets / min by a predetermined speed (5 sheets / min) to change the printing speed. The speed is set to 50 sheets / min. By adjusting the printing speed in this way, the predicted value of the temperature output from the first temperature sensor 130 is as shown in FIG. The time required to complete printing has increased from T1 to T2 due to the reduction in printing speed, but continuous printing has been completed because the temperature change per unit time has slowed due to the reduction in printing speed. At the time T2, the temperature does not become equal to or higher than the predetermined threshold temperature A.

  Note that the operation control unit 101 determines, for the predicted value of one temperature at which the highest temperature is calculated, among the predicted values of the temperatures of the plurality of first temperature sensors 130 provided for the developing devices 122 of the respective colors, It is determined whether or not the predicted value of the temperature is equal to or higher than a threshold.

  As described above, according to the above-described image forming apparatus 1, instead of changing the printing speed based only on the current temperature, a predicted value of the temperature after the present is calculated and the predicted value of the calculated temperature is calculated. Since the printing speed is changed based on the temperature, the temperature in the image forming apparatus can be more reliably prevented from becoming high during continuous printing even in a situation where the temperature in the image forming apparatus may suddenly increase. It is possible to avoid a situation in which the formation quality is deteriorated or the image forming operation is unstable.

  Note that the present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

<Modification 1>
In the above-described embodiment, the case where the operation control unit 101 reduces the printing speed by a predetermined speed for each process of step S17 has been described. On the other hand, in the image forming apparatus according to the first modification, similarly to the above-described embodiment, the operation control unit 101 decreases the printing speed by a predetermined speed at each process of step S17. If the printing speed is equal to or lower than the predetermined speed, continuous printing by the printing unit is interrupted for a predetermined time without further lowering the printing speed. Then, the operation control unit 101 restarts continuous printing by the printing unit after a predetermined time has elapsed.

  As described above, according to the image forming apparatus according to the first modification, it is possible to avoid a situation in which continuous printing takes an enormous amount of time due to too low a printing speed.

<Modification 2>
In the above embodiment, the case where the operation control unit 101 determines whether or not the predicted value of the temperature is equal to or larger than the threshold value by the time when the continuous printing of the number of prints indicated by the print instruction is completed. On the other hand, in the image forming apparatus according to the second modification, when the number of unprinted prints that have not been printed by the printing unit among the number of prints indicated by the print instruction is less than the predetermined number N, The operation control unit 101 performs the same processing as in the above embodiment. On the other hand, when the number of unprinted prints that have not been printed by the printing unit out of the number of prints indicated by the print instruction is equal to or greater than the predetermined number N, the operation control unit 101 determines the number of prints indicated by the print instruction. It is determined whether or not the predicted value of the temperature is equal to or larger than the threshold value, not until the time when the continuous printing is completed but before the continuous printing of the predetermined number N is completed. Then, when the temperature is equal to or higher than a predetermined threshold, the operation control unit 101 reduces the printing speed of the printing unit to perform continuous printing.

  If the number of prints indicated by the print job is large (for example, 1000), even if the current temperature is low, the predicted value calculation unit 102 calculates the time at which it is predicted that continuous printing of 1000 sheets will be completed. The temperature may be equal to or higher than a predetermined threshold. In this case, since the printing speed is reduced from the beginning of the continuous printing, the time required for a large amount of continuous printing becomes enormous. In this regard, in the image forming apparatus according to the second modification, by performing the above-described processing, it is possible to prevent a situation where the printing speed is reduced in a low temperature state.

<Modification 3>
FIG. 6 is a diagram illustrating an example of an operation mode selection screen displayed on the display unit 473 in the image forming apparatus according to the third modification. As shown in the figure, a button d1 for receiving a predetermined first operation mode and a button d2 for receiving a predetermined second operation mode are arranged on the operation mode selection screen D1. I have. The receiving unit 104 receives an operation mode selection instruction according to a pressing operation on the button d1 or d2.

  When the receiving unit 104 receives an operation mode selection instruction instructing to operate in the first operation mode, the operation control unit 101 performs the same processing as in the above embodiment. On the other hand, when the receiving unit 104 receives an operation mode selection instruction instructing to operate in the second operation mode, the operation control unit 101 determines whether the predicted value of the temperature is equal to or higher than the threshold. If the temperature detected by the first temperature sensor 130 is equal to or higher than the threshold without performing the process of performing the printing, the process of interrupting the continuous printing by the printing unit is performed.

  Depending on the use environment of the image forming apparatus and the preference of the user, it may be preferable to temporarily stop the continuous printing until the temperature decreases, rather than performing the continuous printing at a reduced printing speed. According to the image forming apparatus of the third modification, the user selects whether to perform the operation of performing continuous printing by reducing the printing speed or to perform the operation of temporarily stopping continuous printing until the temperature decreases. It becomes possible.

<Other modifications>
Further, the image forming apparatus control program described in the above embodiments and modifications is recorded on a non-transitory computer-readable recording medium such as a hard disk, a CD-ROM, a DVD-ROM, and a semiconductor memory. Is also good.

REFERENCE SIGNS LIST 1 image forming apparatus 10 control unit 12 image forming unit 13 fixing unit 47 operation unit 100 control unit 101 operation control unit 102 prediction value calculation unit 103 display control unit 104 reception unit 122 developing device 123 charging device 130 first temperature sensor 140 second Temperature sensor 150 Third temperature sensor 473 Display

Claims (8)

A printing unit;
A receiving unit for receiving a print instruction,
An operation control unit that controls a printing operation by the printing unit, and causes the printing unit to perform continuous printing of the number of prints indicated by the print instruction at a predetermined printing speed .
A temperature sensor provided in the image forming apparatus;
While the printing unit is performing continuous printing, a signal indicating the temperature detected by the temperature sensor is acquired every predetermined time, and the temperature detected by the temperature sensor at the time when the signal is acquired. Using the temperature detected by the temperature sensor before the time when the signal was obtained, and calculating an approximate curve indicating a predicted value of the temperature in the image forming apparatus after the time when the signal was obtained. And, among the number of prints indicated by the print instruction, based on the number of unprinted prints that have not been printed by the printing unit at the time of acquiring the signal and the predetermined printing speed, A predicted value calculation unit that repeats a process of calculating a print completion time at which printing is completed ,
The operation control unit is configured such that each time the predicted value calculation unit calculates the approximate curve and the print completion time , the predicted value of the temperature indicated by the approximate curve is predetermined by the print completion time. and whether repeats a process of determining a threshold value or more and becomes, if the predicted value of the temperature in the processing is more than a predetermined threshold value is defined a print speed of the is predetermined in advance An image forming apparatus that performs the continuous printing with a delay by a value. The printing unit includes an image carrier, a charging device that charges a peripheral surface of the image carrier, and a peripheral surface of the image carrier that is exposed to form an electrostatic latent image on the peripheral surface of the image carrier. An image forming unit including an exposure device and a developing device that contains a developer and develops the electrostatic latent image formed on the peripheral surface of the image carrier,
The image forming apparatus according to claim 1, wherein the temperature sensor is disposed in the developing device or in the vicinity of the developing device. The printing unit includes a plurality of the image forming units,
The temperature sensor is disposed one by one in the developing device of each of the image forming units or in the vicinity of the developing device,
For each of the plurality of temperature sensors, the predicted value calculation unit calculates a predicted value of the temperature after the signal is obtained,
The operation control unit determines whether or not one of the plurality of predicted values calculated by the predicted value calculation unit that has the highest calculated temperature is equal to or larger than the threshold value. An image forming apparatus according to claim 1. The operation control unit, when the number of unprinted prints in continuous printing based on the print instruction is equal to or more than a predetermined number of prints less than the number of prints indicated by the print instruction, the number of prints indicated by the print instruction It is determined whether or not the predicted value of the temperature is equal to or more than the threshold, not until the time when the continuous printing of the predetermined number is completed, but before the continuous printing of the predetermined number of sheets is completed, and the temperature is determined in advance. when the threshold value or more, the to perform continuous printing using a slower print speed of the printing unit, the image forming apparatus according to any one of claims 1 to 3. The operation control unit, when the printing speed by slowing the printing speed of the printing unit is equal to or less than a predetermined speed, thereby interrupting the continuous printing by the printing unit, one of claims 1 to 4 2. The image forming apparatus according to claim 1. The receiving unit further receives an operation mode selection instruction for instructing which of the predetermined first operation mode and the second operation mode to operate,
The operation control unit, (1) when the receiving unit receives an operation mode selection instruction instructing to operate in the first operation mode, determines whether the predicted value of the temperature is equal to or more than the threshold. If the temperature is equal to or higher than a predetermined threshold value, the printing speed by the printing unit is reduced to perform the continuous printing, and (2) the receiving unit operates in the second operation mode. When an operation mode selection instruction is received to indicate that the temperature detected by the temperature sensor is equal to or greater than the threshold without determining whether the predicted value of the temperature is equal to or greater than the threshold. , to interrupt the continuous printing by the printing unit, the image forming apparatus according to any one of claims 1 to 4. The operation control unit, by changing the process speed during the printing operation the printing unit performs the change in the printing speed, the image forming apparatus according to any one of claims 1 to 6. The operation control unit, by changing the paper feeding interval of the recording sheet during the continuous printing operation to the printing unit performs the change in the printing speed, according to any one of claims 1 to 6 Image forming device.