JP2020071334A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can improve throughput without reducing print quality.SOLUTION: An image forming apparatus comprises: photoconductor drums; a transfer unit that has a transfer belt; a print control unit; an internal temperature detection unit that detects an apparatus internal temperature (Tmi) that is the temperature of the transfer unit; an outside air temperature detection unit that detects an outside temperature (Tme); and a time measuring unit that measures time (te). When the apparatus internal temperature (Tmi) becomes equal to or more than a predetermined threshold (Ty), the print control unit stops the drive of the photoconductor drums and transfer unit, and when an elapsed time (te) measured by the time measuring unit reaches a set time (tw), starts an idling operation (S7, S8, S9, S10), and determines the set time (tw) based on the apparatus internal temperature (Tmi) and outside air temperature (Tme) (S2 to S6).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  It is known that in an image forming apparatus using an electrophotographic system, when the temperature inside the apparatus rises excessively, the toner contained in the developing device as a developer deteriorates (that is, deteriorates). In a conventional image forming apparatus, in order to prevent an excessive temperature rise in the apparatus, control is performed to stop printing based on the detected temperature in the apparatus. That is, in the conventional image forming apparatus, when the temperature inside the apparatus becomes equal to or higher than a predetermined threshold value, the printing operation is stopped to enter the print stop state, and in the print stop state, the temperature inside the apparatus becomes less than the threshold value. When it drops, the printing stop state is released and the printing is enabled.

  In addition, there is an image forming apparatus in which an internal temperature sensor that detects the temperature inside the apparatus is arranged so as to come into contact with the transfer belt (see, for example, Patent Document 1). In such an apparatus, the temperature of the transfer belt is detected to detect the temperature of the photosensitive drum in contact with the transfer belt and the temperature of the developing device having the developing roller in contact with the photosensitive drum. ..

JP, 2018-72382, A

  However, in an apparatus that detects the temperature inside the apparatus by an internal temperature sensor that contacts the transfer belt, when the temperature decrease of the transfer belt is faster than the temperature decrease of the developing device, the actual temperature of the developing device is equal to or higher than the threshold value. Nevertheless, the temperature in the device may be determined to be below a threshold. Therefore, there is a problem that the print stop state is released even though the actual temperature of the developing device is equal to or higher than the threshold value, and as a result, a printed matter with low print quality may be provided.

  Further, in the image forming apparatus that detects the temperature inside the apparatus by the internal temperature sensor, when the temperature decrease of the transfer belt is slower than the temperature decrease of the developing device, the actual temperature of the developing device is less than the threshold value. In some cases, it may be determined that the temperature inside the device is equal to or higher than the threshold value. In this case, there is a problem that the print stop state is not released even though the print stop state should be released, and as a result, provision of the printed matter is delayed (that is, throughput is reduced).

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus capable of improving throughput without deteriorating print quality.

  An image forming apparatus according to an aspect of the present invention includes a first image carrier that carries a first toner image and a transfer belt that is in contact with the first image carrier. Corresponding to the outside air temperature, a transfer unit for transferring the toner image, a control unit for controlling the driving of the first image carrier and the transfer unit, a first detection unit for detecting the temperature of the transfer unit, A second detection unit that detects a temperature and a measurement unit that measures time are provided, and the control unit is provided when the temperature detected by the first detection unit is equal to or higher than a predetermined threshold value. When the driving of the first image carrier and the transfer unit is stopped and the elapsed time measured by the measuring unit reaches a set time, the first toner image is not formed and the first toner image is not formed. No. 1 image carrier and the transfer belt are rotated to start the idling operation, Detecting section based on the detected by the second detector and the detected temperature the temperature by and determines the setting time.

  According to the image forming apparatus of the present invention, the throughput can be improved without deteriorating the print quality.

FIG. 1 is a vertical cross-sectional view schematically showing a configuration of an image forming apparatus according to a first exemplary embodiment of the present invention. FIG. 3 is a block diagram schematically showing the configuration of a control system of the image forming apparatus according to the first embodiment. 3 is a flowchart showing the operation of the image forming apparatus according to the first embodiment. (A) is an explanatory view showing a change in temperature distribution in the conventional image forming apparatus (comparative example) after printing is stopped, and (b) and (c) are the images according to the first embodiment. FIG. 6 is an explanatory diagram showing a change in temperature distribution in the forming apparatus after printing is stopped. 6 is a graph showing changes in temperature inside the conventional image forming apparatus (comparative example) and the image forming apparatus according to the first embodiment after printing is stopped. 8 is a flowchart showing an operation after stopping printing of the image forming apparatus according to the second embodiment of the present invention. FIG. 9 is a diagram showing an example of a table used by the image forming apparatus according to the second embodiment.

  An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The following embodiments are merely examples, and various modifications can be made within the scope of the present invention.

<< 1 >> First Embodiment << 1-1 >> Configuration of First Embodiment FIG. 1 is a vertical cross-sectional view schematically showing the configuration of an image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is, for example, a color printer that uses an electrophotographic process.

  As shown in FIG. 1, the image forming apparatus 100 has, as a main component, an image forming unit (that is, a process) that forms a toner image (that is, a developer image) on a recording medium P such as a sheet by an electrophotographic process. (Unit) 10K, 10C, 10M, 10Y, a medium supply unit 20 for supplying the recording medium P to the image forming units 10K, 10C, 10M, 10Y, a recording medium P is conveyed, and a toner image is transferred onto the recording medium P. A transfer unit 30, a fixing device 40 for fixing the toner image transferred on the recording medium P, and a medium discharging unit for discharging the recording medium P passing through the fixing device 40 to the outside of the housing of the image forming apparatus 100. A guide 26, a pair of discharge rollers 27, and a housing 50 are provided. Each of the image forming units 10K, 10C, 10M, and 10Y is also referred to as the image forming unit 10. The number of image forming units included in the image forming apparatus 100 may be 3 or less or 5 or more. Further, the image forming apparatus 100 may be a monochrome printer having one image forming unit.

  In addition, as shown in FIG. 1, the image forming apparatus 100 includes an internal temperature detection unit 81 as a first detection unit that detects the temperature of the transfer unit 30 and a second temperature detection unit that detects a temperature corresponding to the outside air temperature. An outside air temperature detecting section 82 as a detecting section is provided. In FIG. 1, the internal temperature detection unit 81 is in contact with the transfer belt 33. The internal temperature detecting unit 81 indirectly measures the temperatures of the photosensitive drum 13 and the developing unit 15 (including the developing roller 16) by measuring the temperature of the transfer belt 33. However, the internal temperature detection unit 81 may be arranged so as to face the transfer belt 33 with a space therebetween. The outside air temperature detection unit 82 is arranged inside the housing 50 of the image forming apparatus 100 and near the inner surface of the housing 50. However, the outside air temperature detection unit 82 may be arranged outside the housing 50. The temperature detected by the internal temperature detection unit 81 is the temperature inside the housing 50 (that is, inside the device), and is also referred to as the “device internal temperature Tmi”. The temperature detected by the outside air temperature detection unit 82 is a temperature corresponding to the temperature of outside air outside the housing 50, and is also simply referred to as “outside air temperature Tme”.

  As shown in FIG. 1, the medium supply unit 20 includes a medium tray 21, a paper feed roller 22 for feeding the recording mediums P one by one from a plurality of recording media stacked in the medium tray 21, and a medium tray 21. A roller pair 23 that conveys the recording medium P that has been fed out, a guide 24 that guides the recording medium P, and a roller pair 25 that corrects the skew of the recording medium P are provided. The roller pair 25 is composed of a registration roller and a pinch roller.

  The image forming units 10K, 10C, 10M, and 10Y form a black (K) toner image, a yellow (Y) toner image, a magenta (M) toner image, and a cyan (C) toner image on the recording medium P. Form each. The image forming units 10K, 10C, 10M, and 10Y are arranged side by side along the medium transport path from the upstream side to the downstream side in the transport direction of the recording medium P (that is, from right to left in FIG. 1). Each of the image forming units 10K, 10C, 10M and 10Y may be a detachable unit. The image forming units 10K, 10C, 10M, and 10Y have basically the same structure except that the colors of the toners contained therein are different from each other.

  The image forming units 10K, 10C, 10M and 10Y have exposure heads 11K, 11C, 11M and 11Y which are optical print heads for respective colors. The exposure heads 11K, 11C, 11M and 11Y include a light emitting element array in which a plurality of light emitting elements are arranged. Each of the exposure heads 11K, 11C, 11M, and 11Y is also referred to as an exposure head 11. The light emitting element is, for example, a light emitting thyristor or a light emitting diode.

  The image forming units 10K, 10C, 10M, and 10Y uniformly charge the surfaces of the photosensitive drums 13K, 13C, 13M, and 13Y, which are rotatably supported as image bearing members, and the photosensitive drums 13K, 13C, 13M, and 13Y. After forming electrostatic latent images on the surfaces of the charging rollers 14K, 14C, 14M and 14Y as charging members and the exposure heads 11K, 11C, 11M and 11Y, the photosensitive drums 13K, 13C, 13M and 13Y are exposed to light. The drums 13K, 13C, 13M, and 13Y are provided with developing units 15K, 15C, 15M, and 15Y that supply toner to the surfaces to form toner images corresponding to electrostatic latent images. Each of the photosensitive drums 13K, 13C, 13M and 13Y is also referred to as a photosensitive drum 13. Each of the charging rollers 14K, 14C, 14M and 14Y is also referred to as a charging roller 14. Each of the developing units 15K, 15C, 15M and 15Y is also referred to as a developing unit 15.

  The developing units 15K, 15C, 15M, and 15Y are toner accommodating units that form a developer accommodating space for accommodating toner and developing as a developer carrier that supplies toner to the surfaces of the photosensitive drums 13K, 13C, 13M, and 13Y. The rollers 16K, 16C, 16M, 16Y, the supply rollers 17K, 17C, 17M, 17Y for supplying the toner contained in the toner accommodating section to the developing rollers 16K, 16C, 16M, 16Y, and the developing rollers 16K, 16C, 16M, The developing blades 18K, 18C, 18M and 18Y are provided as toner regulating members for regulating the thickness of the toner layer on the surface of 16Y. Each of the developing rollers 16K, 16C, 16M and 16Y is also referred to as a developing roller 16. Each of the supply rollers 17K, 17C, 17M, and 17Y is also referred to as a supply roller 17. Each of the developing blades 18K, 18C, 18M and 18Y is also referred to as a developing blade 18.

  The irradiation of light by the exposure heads 11K, 11C, 11M and 11Y is performed on the surface of the uniformly charged photosensitive drums 13K, 13C, 13M and 13Y based on the print data.

  As shown in FIG. 1, the transfer unit 30 includes a transfer belt 33 that electrostatically attracts and conveys the recording medium P, a drive roller 31 that is rotated by a drive unit and drives the transfer belt 33, and a drive roller 31. A tension roller (following roller) 32 that forms a pair and stretches the transfer belt 33, and transfer rollers 35K, 35C, 35M, and 35Y that are arranged to face the image forming units 10K, 10C, 10M, and 10Y. I have it. Each of the transfer rollers 35K, 35C, 35M and 35Y is also referred to as a transfer roller 35.

  As shown in FIG. 1, the transfer rollers 35K, 35C, 35M, and 35Y are arranged to face the photosensitive drums 13K, 13C, 13M, and 13Y with the transfer belt 33 interposed therebetween. The toner images formed on the surfaces of the photosensitive drums 13K, 13C, 13M, and 13Y are conveyed along the medium conveyance path (here, the upper surface of the transfer belt 33) by the transfer rollers 35K, 35C, 35M, and 35Y (arrows). Direction) is sequentially transferred onto the upper surface of the recording medium P. The image forming units 10K, 10C, 10M, and 10Y include cleaning devices 19K, 19C, 19M, and 19Y that remove toner remaining on the photosensitive drums 13K, 13C, 13M, and 13Y.

  The fixing device 40 has a pair of rollers 41 and 42 which are in pressure contact with each other. The roller 41 is a heat roller having a built-in heater. The roller 42 is a pressure roller pressed against the roller 41. The recording medium P having the unfixed toner image passes between the pair of rollers 41 and 42 of the fixing device 40. At this time, the unfixed toner image is heated and pressed to be fixed on the recording medium P.

  Further, on the lower surface side of the transfer belt 33, a cleaning blade 34 for removing toner and the like adhering to the surface of the transfer belt 33, and a waste toner storage portion (not shown) for storing the removed toner and the like are provided. There is.

  At the time of printing, the recording medium P in the medium tray 21 is delivered by the paper feed roller 22 and sent to the roller pair 23. Then, the recording medium P is sent from the roller pair 23 to the transfer belt 33 via the guide 24 and the roller pair 25. The recording medium P is conveyed to the image forming units 10K, 10C, 10M, and 10Y as the transfer belt 33 travels. In the image forming units 10K, 10C, 10M and 10Y, the surfaces of the photosensitive drums 13K, 13C, 13M and 13Y are charged by the charging rollers 14K, 14C, 14M and 14Y and exposed by the exposure heads 11K, 11C, 11M and 11Y. As a result, an electrostatic latent image is formed. Toner that is thinned on the developing rollers 16K, 16C, 16M, and 16Y is electrostatically attached to the electrostatic latent image to form a toner image on the surface of the photosensitive drums 13K, 13C, 13M, and 13Y. To be done. The toner image is transferred onto the recording medium P moving in the transport direction by the transfer rollers 35K, 35C, 35M, 35Y. As a result, a color toner image is formed on the recording medium P. After the transfer, the toner remaining on the photosensitive drums 13K, 13C, 13M and 13Y is removed by the cleaning devices 19K, 19C, 19M and 19Y. The recording medium P on which the color toner image is formed is sent to the fixing device 40. In the fixing device 40, the color toner image is fixed on the recording medium P to form a color image. The recording medium P on which the color image is formed is conveyed along the guide 26 and is ejected onto the stacker cover 51 by the pair of paper ejection rollers 27.

  FIG. 2 is a block diagram showing the configuration of the control system of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 includes a print control unit 84, a transfer bias power supply 135, a charging bias power supply 114, a developing bias power supply 116, a supply bias power supply 117, a drum drive unit 113, a transfer drive unit 131, and a fixing drive. The unit 140 and the transport drive unit 120 are provided. The image forming apparatus 100 also includes a head drive controller 86. The print control unit 84 includes a storage unit 84a such as a memory. The storage unit 84a may be provided outside the print control unit 84. The storage unit 84a stores thresholds (for example, Tz, Ty, Tx, Tw, Tv) that are various set temperatures described below, and set times (for example, tw) described below.

  The print control unit 84 receives a print command and print data from a host device such as a computer, and controls the print operation of the image forming apparatus 100. The bias application controller 85 controls the bias voltage output by the transfer bias power supply 135, the charging bias power supply 114, the developing bias power supply 116, and the supply bias power supply 117. Bias voltages output from the transfer bias power supply 135, the charging bias power supply 114, the developing bias power supply 116, and the supply bias power supply 117 are supplied to the transfer roller 35, the charging roller 14, the developing roller 16, and the supply roller 17, respectively.

  Each of the drum driving unit 113, the transfer driving unit 131, and the conveyance driving unit 120 has a driving force generating unit such as a motor that generates a driving force and a driving force such as a gear that transmits the driving force generated by the driving force generating unit. And a transmission unit. The drum driving unit 113, the transfer driving unit 131, and the conveyance driving unit 120 respectively include the photosensitive drum 13, the driving roller 31, and a roller or a roller pair (for example, roller pairs 23, 25, 27) for conveying the recording medium P. These are rotated by applying a driving force to them.

  The head drive control unit 86 controls the light emission of the exposure head 11 based on the print data provided by the print control unit 84. The time measuring unit 83 measures the timer value from the time when the measurement start command is received from the print control unit 84, that is, the elapsed time te, and transmits it to the print control unit 84. The time when the measurement of the elapsed time te is started may be the time when the apparatus internal temperature Tmi detected by the internal temperature detection unit 81 detects the start temperature Ty of the printing stopped state.

  The configuration of the image forming apparatus 100 is not limited to that shown in FIG. 1, and various modifications can be made.

<< 1-2 >> Operation of First Embodiment (Normal Printing Operation)
When the print control unit 84 outputs a print command, the image forming apparatus 100 conveys the recording medium P to the transfer belt 33 by the paper feed roller 22, the roller pair 23, and the roller pair 25. In each image forming unit 10, an electrostatic latent image is formed on the photosensitive drum 13 exposed by the exposure head 11. The electrostatic latent image on the photosensitive drum 13 is developed by the developing unit 15. The toner image formed on the photosensitive drum 13 by the development reaches a position facing the transfer belt 33 as the photosensitive drum 13 rotates, and is transferred onto the recording medium P by the transfer roller 35. The recording medium P having the toner image moves in the transport direction and passes through the fixing device 40. The fixing device 40 fixes the toner image on the recording medium P. After that, the recording medium P is discharged onto the stacker cover 51 by the pair of discharge rollers 27.

(Printing operation when the device internal temperature Tmi is high)
The print control unit 84 controls the printing operation based on the detection value detected by the internal temperature detection unit 81, that is, the apparatus internal temperature Tmi [° C.]. Table 1 shows the relationship between the apparatus internal temperature Tmi [° C.] and the control content of the print control unit 84. However, the values of the set temperatures (starting temperature or releasing temperature) Ty, Tz, Tx, Tw, Tv are not limited to the values shown in Table 1.

  When the device internal temperature Tmi detected by the internal temperature detecting unit 81 is less than 42 ° C. (that is, the start temperature Tw in the decelerated printing state), the print control unit 84 causes the image forming apparatus 100 to perform normal printing at a normal printing speed. Let it run. That is, when the internal temperature Tmi of the apparatus is less than 42 ° C., the image forming apparatus 100 performs normal printing. In normal printing, the rotational linear velocity of the photosensitive drum 13 is a predetermined speed during normal printing (for example, 178.5 [mm / s]).

  When the internal temperature Tmi of the apparatus is 42 ° C. (that is, the start temperature Tw of the decelerated printing state) or more and less than 43 ° C., the print control unit 84 causes the image forming apparatus 100 to decelerate at a printing speed slower than the normal printing speed. Print it. That is, when the internal temperature Tmi of the apparatus is 42 ° C. or more and less than 43 ° C., the image forming apparatus 100 performs deceleration printing. In deceleration printing, the rotational linear velocity of the photosensitive drum 13 is a predetermined deceleration printing velocity (for example, 95.2 [mm / s]).

  The print control unit 84 causes the image forming apparatus 100 to perform intermittent printing when the apparatus internal temperature Tmi is 43 ° C. (that is, the start temperature Tx in the intermittent printing state) or more and less than 44 ° C. In intermittent printing, after decelerating printing on one recording medium P, the printing operation is temporarily stopped, and when a predetermined time has elapsed, the operation of decelerating printing on the next recording medium P is repeated. In other words, in the intermittent printing, the deceleration printing and the temporary stop of the printing operation are alternately executed.

  When the internal temperature Tmi of the apparatus is 44 ° C. or higher (that is, the start temperature Ty of the print stop state) or more, the print control unit 84 stops the print operation by the image forming apparatus 100 and sets the print stop state.

  The print control unit 84 sets the release temperature Tz in the print stopped state to 41 ° C. The print control unit 84 sets the deceleration printing state release temperature Tv to 41 ° C.

(Operation when printing is stopped)
The image forming apparatus 100 is in a print stop state in which the printing operation is not executed when the internal temperature Tmi of the apparatus reaches a predetermined print stop start temperature (for example, Ty = 44 ° C.). Further, the print control unit 84 stops the printing operation when the device internal temperature Tmi reaches a predetermined print stop state start temperature Ty = 44 ° C., and the device internal temperature Tmi is a predetermined print stop. When the state release temperature Tz is less than 41 ° C., the print stop state is released.

  However, when the print stop state is released even though the actual temperature of the developing unit 15 containing the toner is high, a printed matter with low print quality is provided. Further, if the printing stop state is not released even though the actual temperature of the developing unit 15 is sufficiently low, the provision of the printed matter is delayed.

  Therefore, the image forming apparatus 100 performs the idling operation of the developing roller 16, the photosensitive drum 13, and the transfer belt 33 at an appropriate timing after the printing is stopped, and moves the heat between the developing roller 16 and the photosensitive drum 13, Further, by transferring heat between each photosensitive drum 13 and the transfer belt 33, the temperatures of the developing roller 16, the photosensitive drum 13, and the transfer belt 33 are made uniform. The idling operation is, for example, an operation of rotating the photosensitive drum 13 and the transfer belt 33 without forming a toner image on the photosensitive drum 13. The idling operation may be, for example, an operation of rotating the developing roller 16, the photosensitive drum 13, and the transfer belt 33 without forming a toner image on the photosensitive drum 13. If the temperature of the transfer belt 33 is detected after the idling operation, the internal temperature Tmi of the apparatus becomes close to the actual temperature of the developing roller 16 and the photosensitive drum 13. At this time, the execution start timing of the first idling operation is determined based on the device internal temperature Tmi detected by the internal temperature detection unit 81 and the outside air temperature Tme detected by the outside air temperature detection unit 82. In the first embodiment, the execution start timing of the first idling operation is determined based on the temperature difference ΔTmie [° C] (= Tmi−Tme) obtained by subtracting the outside air temperature Tme from the device internal temperature Tmi. To be done.

  Table 2 shows the relationship between the temperature difference ΔTmie [° C.] (= Tmi−Tme) in the image forming apparatus 100, the execution start timing of the first idling operation, and the execution start timing of the idling operation after the second idling operation. .. In Table 2, the reason why the set time tw before the start of the first idling operation is different is that the inside of the device is cooled more quickly as the outside air temperature is lower. That is, the lower the outside air temperature Tme and the larger ΔTmie, the faster the temperature inside the apparatus decreases, so the set time tw before the start of the first idling operation is shortened. In Table 2, the set time tx until the start of the second idling operation is the same because the internal temperature Tmi of the apparatus is canceled when the idling operation is performed after the second idling operation. This is because it is expected that the temperature is close to the temperature Tz. However, the values of the set times tw and tx are not limited to the values shown in Table 2.

  The printing control unit 84 stops the printing operation when the internal temperature Tmi of the apparatus reaches the start temperature Ty = 44 ° C. in the printing stopped state. This state is also referred to as a print stop state. The print control unit 84 resets the timer value of the time measuring unit 83, that is, the elapsed time te to 0 at the start of the print stopped state.

  The print control unit 84 executes the first idling operation when the elapsed time te of the time measuring unit 83 reaches the time shown in Table 2 with respect to the difference ΔTmie between the device internal temperature Tmi and the outside air temperature Tme. To do. By the idling operation, heat is transferred from the developing roller 16 to the photosensitive drum 13, and further from the photosensitive drum 13 to the transfer belt 33, so that the temperatures of the developing roller 16, the photosensitive drum 13, and the transfer belt 33 are made uniform. The print control unit 84 resets the timer value of the time measuring unit 83, that is, the elapsed time te to 0 at the time of the first idling operation.

  If the internal temperature Tmi of the apparatus is lower than the release temperature Tz (for example, 41 ° C.) of the print stop state after the first idling operation, the print control unit 84 releases the print stop state. If there is print data when the print stopped state is released, the print control unit 84 restarts the print operation.

  Further, if the internal temperature Tmi of the apparatus is equal to or higher than the release temperature Tz (for example, 41 ° C.) of the printing stopped state, the print control unit 84 sets the elapsed time te of the time measuring unit 83 to a predetermined set time (for example, 5 minutes). When the time has elapsed, the second idling operation is executed, and it is determined again whether or not the print stop state can be released. Such an operation is repeated until the internal temperature Tmi of the apparatus becomes lower than the release temperature Tz of the printing stopped state.

  It is desirable that the print control unit 84 controls the idling operation so that the transfer belt 33 makes one rotation or more.

  Further, it is desirable that the print control unit 84 controls the idling operation so that the entire area of the surface of the transfer belt 33 in the circumferential direction contacts all the photosensitive drums 13.

  Further, the print control unit 84 preferably controls the idling operation so that the entire area of the surface of all the photosensitive drums 13 in the circumferential direction contacts the transfer belt 33 at least once.

(Details of operation when printing is stopped)
FIG. 3 is a flowchart showing the operation of the image forming apparatus 100 according to the first embodiment after the start of the print stop state (the print stop when the start temperature Ty [° C.] of the print stop state is reached).

  In step S1, the print control unit 84 resets the timer value of the time measuring unit 83, that is, the elapsed time te to 0.

  In step S2, the print control unit 84 determines whether the temperature difference ΔTmie obtained by subtracting the outside air temperature Tme from the device internal temperature Tmi is 12 ° C. or less, which is a predetermined temperature difference. The print control unit 84 advances the process to step S4 if the temperature difference ΔTmie is 12 ° C. or less, and advances the process to step S3 if the temperature difference ΔTmie is higher than 12 ° C.

  In step S3, the print control unit 84 determines whether the temperature difference ΔTmie is 16 ° C. or less, which is a predetermined temperature difference. The print control unit 84 advances the process to step S5 if the temperature difference ΔTmie is 16 ° C. or less, and advances the process to step S6 if the temperature difference ΔTmie is higher than 16 ° C.

  In step S4, the print control unit 84 determines whether the apparatus internal temperature Tmi is lower than the print stop release temperature Tz. The print control unit 84 advances the process to step S7 if the device internal temperature Tmi is equal to or higher than the print stop release temperature Tz, and the process proceeds to step S7 if the device internal temperature Tmi is lower than the print stop release temperature Tz. Proceed to S14.

  In step S5, the print control unit 84 determines whether the apparatus internal temperature Tmi is lower than the print stop release temperature Tz. If the device internal temperature Tmi is equal to or higher than the print stop release temperature Tz, the print control unit 84 proceeds to step S8. Proceed to S14.

  In step S6, the print control unit 84 determines whether the apparatus internal temperature Tmi is lower than the print stop release temperature Tz. The print control unit 84 advances the process to step S9 if the device internal temperature Tmi is equal to or higher than the print stop release temperature Tz, and the process proceeds to step S9 if the device internal temperature Tmi is lower than the print stop release temperature Tz. Proceed to S14.

  In step S7, the print control unit 84 determines whether the elapsed time te measured by the time measuring unit 83 is 15 minutes or more, which is a predetermined set time. If the elapsed time te is 15 minutes or more, the print control unit 84 advances the process to step S10, and if the elapsed time te is less than 15 minutes, returns the process to step S4.

  In step S8, the print control unit 84 determines whether the elapsed time te measured by the time measuring unit 83 is 10 minutes or more, which is a predetermined set time. If the elapsed time te is 10 minutes or more, the print control unit 84 advances the process to step S10, and if the elapsed time te is less than 10 minutes, returns the process to step S5.

  In step S9, the print control unit 84 determines whether the elapsed time te measured by the time measuring unit 83 is 5 minutes or more, which is a predetermined set time. If the elapsed time te is 5 minutes or more, the print controller 84 advances the process to step S10, and if the elapsed time te is less than 5 minutes, returns the process to step S6.

  In step S10, the print control unit 84 executes the first idling operation. The print control unit 84 rotates all the developing rollers 16, all the photosensitive drums 13, and the transfer belt 33 in the first idling operation. Further, at this time, the print control unit 84 resets the timer value of the time measuring unit 83, that is, the elapsed time te to zero. The print control unit 84 advances the process to step S11 after the first idling operation.

  In step S11, the print control unit 84 determines whether the device internal temperature Tmi is lower than the print stop release temperature Tz. If the device internal temperature Tmi is lower than the print stop release temperature Tz, the print control unit 84 advances the process to step S14. If the device internal temperature Tmi is equal to or higher than the print stop release temperature Tz, the process proceeds to step S14. Proceed to S12.

  In step S12, the print control unit 84 determines whether the elapsed time te measured by the time measuring unit 83 is 5 minutes or more, which is a predetermined set time. If the elapsed time te is 5 minutes or more, the print control unit 84 advances the process to step S13, and if the elapsed time te is less than 5 minutes, returns the process to step S11.

  In step S13, the print control unit 84 executes the idling operation, that is, the idling operation after the second time. The print control unit 84 rotates all the developing rollers 16, all the photosensitive drums 13, and the transfer belt 33 in the idling operation after the second time. The print control unit 84 returns the process to step S11 after the second and subsequent idling operations.

  When the process proceeds from step S11 to step S14, the print control unit 84 releases the print stop state.

(Example of operation from start to release of print stop status)
FIG. 4A is an explanatory diagram showing a change in temperature distribution in the conventional image forming apparatus (comparative example) after the printing is stopped, and FIGS. 4B and 4C show the first embodiment. FIG. 6 is an explanatory diagram showing a change in temperature distribution in the image forming apparatus 100 according to the embodiment after printing is stopped.

  FIG. 4A shows a state in the conventional image forming apparatus when the outside air temperature Tme is 32 ° C. and the apparatus internal temperature Tmi reaches Ty = 44 ° C. which is the start temperature of the printing stopped state. When the elapsed time te = 0 minutes, the temperature of all the photosensitive drums 13 is 44 ° C., for example.

  When the elapsed time te = 5 minutes in FIG. 4A, the apparatus internal temperature Tmi is 43 ° C. (> Tz = 41 ° C.). At this time, the temperatures of the photosensitive drums 13 are, for example, 43 ° C., 43 ° C., 42 ° C., and 41 ° C. in order from the one closest to the fixing device 40. The reason for the difference in temperature is that the temperature of the photosensitive drum 13 near the fixing device 40, which is a heat source, decreases slowly.

  When the elapsed time te = 15 minutes in FIG. 4A, the internal temperature Tmi of the apparatus is 42 ° C. (> Tz = 41 ° C.). At this time, the temperatures of the photosensitive drums 13 are, for example, 42 ° C., 41 ° C., 41 ° C., and 40 ° C. in order from the one closest to the fixing device 40.

  When the elapsed time te = 30 minutes in FIG. 4A, the device internal temperature Tmi is 41 ° C. (= Tz). At this time, the temperature of the photosensitive drum 13 is, for example, 41 ° C., 40 ° C., 39 ° C., and 38 ° C. in order from the one close to the fixing device 40. As described above, in the conventional image forming apparatus, the print stop state is not released until the temperature of all the photosensitive drums 13 becomes lower than the release temperature Tz of the print stop state, that is, until the elapsed time te = 30 minutes.

  FIG. 4B illustrates the image forming apparatus 100 according to the first embodiment when the outside air temperature Tme is 32 ° C. and the inside temperature Tmi of the apparatus reaches Ty = 44 ° C., which is the start temperature of the printing stop state. Indicates the state of. When the elapsed time te = 0 minutes, the temperature of all the photosensitive drums 13 is 44 ° C., for example.

  When the processing of steps S1, S2, S4 and S7 in FIG. 3 is executed and the elapsed time te = 5 minutes in FIG. 4 (b), the apparatus internal temperature Tmi is 43 ° C. (> Tz = 41 ° C.). At this time, the temperatures of the photosensitive drums 13 are, for example, 43 ° C., 43 ° C., 42 ° C., and 41 ° C. in order from the one closest to the fixing device 40. The reason for the difference in temperature is that the temperature of the photosensitive drum 13 near the fixing device 40, which is a heat source, decreases slowly. Further, the photosensitive drum 13 near the outer wall portion (side wall) 52 of the housing 50 shown in FIG.

  When the processes of steps S4 and S7 in FIG. 3 are executed and the elapsed time te = 15 minutes in FIG. 4 (b), the apparatus internal temperature Tmi is 42 ° C. (> Tz = 41 ° C.). At this time, the temperatures of the photosensitive drums 13 are, for example, 42 ° C., 41 ° C., 41 ° C., and 40 ° C. in order from the one closest to the fixing device 40.

  When the idling operation of steps S10 to S14 in FIG. 3 is executed and the elapsed time te = 15 minutes or later in FIG. 4B, the device internal temperature Tmi is 41 ° C. (= Tz). At this time, the temperatures of the photosensitive drums 13 are, for example, 41 ° C., 41 ° C., 41 ° C., 41 ° C. in order from the one closest to the fixing device 40. As described above, in the image forming apparatus 100 according to the first embodiment, the temperature of the photosensitive drum 13 and the temperature of the transfer belt 33 are equalized by the idling operation, and as a result, the temperature of the developing roller 16 is also the photosensitive drum 13. Since the temperature becomes the same as the temperature of No. 1, the print stop state is released when the elapsed time te = 15 minutes has passed. As described above, the time required to start printing can be shortened by about 15 minutes as compared with the conventional image forming apparatus. That is, the throughput can be improved without deteriorating the print quality.

  FIG. 4C illustrates the image forming apparatus 100 according to the first embodiment when the outside air temperature Tme is 23 ° C. and the inside temperature Tmi of the apparatus reaches Ty = 44 ° C., which is the start temperature of the print stop state. Indicates the state of. When the elapsed time te = 0 minutes, the temperature of all the photosensitive drums 13 is 44 ° C., for example.

  When the processing of steps S1-S3, S6, S9 in FIG. 3 is executed and the elapsed time te = 5 minutes in FIG. 4 (c), the apparatus internal temperature Tmi is 42 ° C. (> Tz = 41 ° C.). At this time, the temperatures of the photosensitive drums 13 are, for example, 42 ° C., 41 ° C., 41 ° C., and 40 ° C. in order from the one closest to the fixing device 40. The temperature of the photosensitive drum 13 is lower than that in FIG. 4B because the outside air temperature is low.

  When the idling operation of steps S10 to S14 in FIG. 3 is executed and the elapsed time te = 5 minutes or later in FIG. 4 (c), the device internal temperature Tmi is 41 ° C. (= Tz). At this time, the temperatures of the photosensitive drums 13 are, for example, 41 ° C., 41 ° C., 41 ° C., 41 ° C. in order from the one closest to the fixing device 40. As described above, in the image forming apparatus 100 according to the first embodiment, the temperature of the photosensitive drum 13 and the temperature of the transfer belt 33 are equalized by the idling operation, and as a result, the temperature of each developing roller 16 is also exposed. Since the temperature of the drum 13 is similar to the temperature of the drum 13, the printing stop state is released when the elapsed time te = 5 minutes has passed. That is, the throughput can be improved without deteriorating the print quality.

  FIG. 5 is a graph showing changes in the internal temperature Tmi of the apparatus after printing is stopped in the conventional image forming apparatus and the image forming apparatus 100 according to the first embodiment. As shown in FIG. 5, according to the image forming apparatus 100 according to the first embodiment, when the outside air temperature Tme = 23 ° C., the time from the start of the print stop state to the release of the print stop state is 5 times. Minutes. When the outside air temperature Tme = 23 ° C., the time from the start of the print stop state to the release of the print stop state in the conventional image forming apparatus is 13 minutes. As described above, according to the image forming apparatus 100 according to the first embodiment, it is possible to quickly release the print stop state for about 8 minutes without degrading the print quality.

  Further, as shown in FIG. 5, according to the image forming apparatus 100 according to the first embodiment, when the outside air temperature Tme = 32 ° C., the time from the start of the print stop state to the release of the print stop state. Is 15 minutes. When the outside air temperature Tme = 32 ° C., it is 30 minutes, which is the time from the start of the print stopped state to the release of the print stopped state in the conventional image forming apparatus. As described above, according to the image forming apparatus 100 according to the first embodiment, it is possible to accelerate the release of the print stop state for about 15 minutes without causing the print quality to deteriorate.

<< 1-3 >> Effect of First Embodiment As described above, in the image forming apparatus 100 according to the first embodiment, the transfer belt 33 is idled to operate, and each developing roller 16 and each photosensitive drum. 13 and the temperature of the transfer belt 33 are made uniform. As described above, after the temperatures of the developing rollers 16, the photosensitive drums 13, and the transfer belt 33 are made uniform, the internal temperature Tmi of the apparatus is detected, so that the actual temperature control of the photosensitive drums 13 and the developing rollers 16 is performed. The temperature can be detected accurately. Therefore, the printing stop state is released at an appropriate timing, printing is resumed at an earlier timing than in the past, and there is an advantage that the user can obtain a printed matter earlier.

  Further, since the time of the first idling operation is determined based on the device internal temperature Tmi and the outside air temperature Tme, it is possible to prevent the idling operation that is too long. Therefore, it is possible to suppress wear of the photosensitive drum 13 due to the idling operation, self-heat generation inside the developing unit 15, and the like.

<< 2 >> Second Embodiment FIG. 6 is a flowchart showing the operation of the image forming apparatus according to the second embodiment after printing is stopped (printing is stopped when the start temperature Ty [° C] in the print stopped state is reached). Is. 6, the same process step as that shown in FIG. 3 is assigned the same step number as that shown in FIG.

  FIG. 7 is a diagram showing an example of a table which is set time information used by the image forming apparatus according to the second embodiment. The table is acquired based on the result of an experiment conducted in advance and is stored in the storage unit 24a in advance. The image forming apparatus according to the second embodiment uses the table shown in FIG. 7 after the printing is stopped, and based on the apparatus internal temperature Tmi and the outside air temperature Tme, the set time until the start of the first idling operation. The point that determines tw [minutes] determines the set time tw [minutes] based on the temperature difference ΔTmie (that is, the processing time of steps S2 to S9 in FIG. 3) according to the first embodiment. Different from the device 100. Note that, in FIG. 7, the range of the device internal temperature Tmi, the range of the outside air temperature Tme, and the value of the set time tw are not limited to the values shown in FIG. 7.

  The image forming apparatus according to the second embodiment is the same as the image forming apparatus 100 according to the first embodiment except for the process of determining the set time tw [minutes] until the start of the first idling operation. Is. Therefore, in describing the second embodiment, reference will also be made to FIGS. 1 and 2 showing the first embodiment.

  As shown in FIG. 6, in the image forming apparatus according to the second embodiment, in step S21, the print control unit 84 uses the table of FIG. 7 and based on the apparatus internal temperature Tmi and the outside air temperature Tme. , The set time tw [minutes] until the start of the first idling operation is determined, and the process proceeds to step S22.

  In step S22, the print control unit 84 determines whether the apparatus internal temperature Tmi is lower than the print stop release temperature Tz. If the device internal temperature Tmi is lower than the print stop state release temperature Tz, the print control unit 84 advances the process to step S23. If the device internal temperature Tmi is the print stop state release temperature Tz or higher, the process proceeds to step S23. Proceed to S14.

  In step S23, the print control unit 84 determines whether the elapsed time te measured by the time measuring unit 83 is the set time tw [minutes] or more. If the elapsed time te is tw [minutes] or more, the print control unit 84 advances the process to step S10. If the elapsed time te is less than tw [minutes], the process returns to step S22.

  The processing of the other steps in FIG. 6 is the same as the processing of the corresponding steps in FIG.

  As described above, in the image forming apparatus according to the second embodiment, the transfer belt 33 is idled and operated to uniformize the temperatures of the developing rollers 16, the photosensitive drums 13, and the transfer belt 33. .. As described above, after the temperatures of the developing rollers 16, the photosensitive drums 13, and the transfer belt 33 are made uniform, the internal temperature Tmi of the apparatus is detected, so that the actual temperature control of the photosensitive drums 13 and the developing rollers 16 is performed. The temperature can be detected accurately. Therefore, the printing stop state is released at an appropriate timing, printing is resumed at an earlier timing than in the past, and there is an advantage that the user can obtain a printed matter earlier.

  Further, since the time of the first idling operation is determined based on the device internal temperature Tmi and the outside air temperature Tme, it is possible to prevent the idling operation that is too long. Therefore, it is possible to suppress wear of the photosensitive drum 13 due to the idling operation, self-heat generation inside the developing unit 15, and the like.

<< 3 >> Description of Usage Mode The image forming apparatuses according to the first and second embodiments are electrophotographic printers, but these are either a copying machine, a facsimile, or an MFP (multifunctional peripheral device). Good.

  10, 10K, 10C, 10M, 10Y image forming unit, 11, 11K, 11C, 11M, 11Y exposure head, 13, 13K, 13C, 13M, 13Y photosensitive drum (image carrier), 15, 15K, 15C, 15M, 15Y developing part (developing device), 16, 16K, 16C, 16M, 16Y developing roller, 20 medium supply part, 30 transfer part, 33 transfer belt, 35, 35K, 35C, 35M, 35Y transfer roller, 40 fixing device, 50 Case, 52 Outer wall part, 81 Inner temperature detecting part (first detecting part), 82 Outer air temperature detecting part (second detecting part), 100 Image forming device, P recording medium, Tmi device inner temperature, Tme Outer air temperature , Ty print stop state start temperature (threshold value), Tz print stop state release temperature (threshold value), te elapsed time, w set time.

Claims (8)

A first image carrier that carries a first toner image;
A transfer unit having a transfer belt in contact with the first image carrier and transferring the first toner image to a recording medium;
A control unit that controls driving of the first image carrier and the transfer unit;
A first detection unit that detects the temperature of the transfer unit;
A second detector for detecting a temperature corresponding to the outside air temperature;
A measuring unit that measures time,
Equipped with
The control unit is
When the temperature detected by the first detection unit exceeds a predetermined threshold value, the driving of the first image carrier and the transfer unit is stopped,
When the elapsed time measured by the measuring unit reaches the set time, the idling operation in which the first image carrier and the transfer belt rotate without forming the first toner image is started. ,
The image forming apparatus, wherein the set time is determined based on a temperature detected by the first detection unit and a temperature detected by the second detection unit.   The control unit determines the set time based on a difference between a temperature detected by the first detection unit and a temperature detected by the second detection unit. Image forming device.   The control unit shortens the set time as the temperature difference obtained by subtracting the temperature detected by the second detection unit from the temperature detected by the first detection unit becomes larger. The image forming apparatus according to claim 1. A storage unit that stores in advance set time information indicating a relationship between the temperature detected by the first detection unit, the temperature detected by the second detection unit, and the set time;
The control unit determines the set time based on the temperature detected by the first detection unit and the temperature detected by the second detection unit, using the set time information. The image forming apparatus according to claim 1. Further comprising a second image carrier for carrying a second toner image,
The second image carrier is in contact with the transfer belt on the upstream side of the first image carrier in the transport direction of the recording medium,
The transfer section transfers the second toner image onto the recording medium,
The control unit controls the idling operation such that the entire circumferential area of the first image carrier and the circumferential entire area of the second image carrier come into contact with the transfer belt at least once. The image forming apparatus according to any one of claims 1 to 4, characterized in that. Further comprising a second image carrier for carrying a second toner image,
The second image carrier is in contact with the transfer belt on the upstream side of the first image carrier in the transport direction of the recording medium,
The transfer section transfers the second toner image onto the recording medium,
The control unit controls the idling operation such that the entire area of the transfer belt in the circumferential direction contacts the first image carrier and the second image carrier at least once. The image forming apparatus according to any one of claims 1 to 4. Further comprising a fixing device for fixing the first toner image and the second toner image on the recording medium,
The fixing device is arranged on the downstream side of the first image carrier in the transport direction of the recording medium,
The distance between the first detection unit and the first image carrier is shorter than the distance between the first detection unit and the second image carrier. The image forming apparatus described. An outer wall portion for partitioning the outside air from the inside of the apparatus including the first image carrier, the second image carrier, and the transfer unit,
The distance between the outer wall portion and the second image bearing member is shorter than the distance between the outer wall portion and the first image bearing member. Image forming device.

Images