JP2014157267A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can reliably prevent fusion of a developer on a developer carrier due to excessive temperature rise while avoiding a reduction in efficiency during continuous image forming operation without performing calculation to estimate temperatures of the developer carrier and developer in a developing device.SOLUTION: An image forming apparatus has temperature detection means for detecting a temperature inside or around a developing device that changes corresponding to a temperature of a developer carrier, provided at a plurality of places in the image forming apparatus, and controls limitation and release of the limitation of the number of pages available for continuous image formation on the basis of a result of the detection by the temperature detection means provided at the plurality of places.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a FAX capable of continuously executing an image forming operation.

  2. Description of the Related Art Conventionally, when a large amount of continuous sheet passing is performed in an electrophotographic image forming apparatus, the image forming unit continues to be driven for a long time, so that the temperature in the image forming apparatus and the temperature of components in the image forming apparatus rise. . In general, this temperature rise is controlled by cooling fans, ducts, etc. so that the temperature inside the image forming apparatus and the temperature of parts do not exceed a certain level. An image forming apparatus having an air conditioner and performing temperature control is already known.

  In addition, in an image forming apparatus in which the temperature of the fixing roller locally rises due to the continuous passage of small-size paper, the temperature of the fixing roller can be monitored directly to temporarily increase the interval between paper passing or Control for leveling the temperature non-uniformity is already known.

  Japanese Patent Application Laid-Open No. 2004-228561 is based on the operation mode of the image forming apparatus for the purpose of appropriately controlling the image forming apparatus so that the temperature of the developing motor is not excessively increased without directly detecting the temperature of the developing motor. Calculate the developing motor fluctuation temperature, estimate the power off time when the power is turned off based on the temperature change of the fixing thermistor, correct the developing motor fluctuation temperature based on the power off time, and correct the developing motor fluctuation An image forming apparatus that calculates an estimated developing motor temperature by adding an environmental temperature to a temperature is disclosed. In this image forming apparatus, when the estimated developing motor temperature becomes 100 ° C. or higher, the image forming process is repeated so that continuous execution of the image forming process and standby without performing the image forming process are repeated until the temperature becomes less than 80 ° C. The forming process is performed intermittently.

  In Patent Document 2, a toner image formed on an image carrier is counted in units of dots for the purpose of preventing toner sticking to a toner regulating member when toner consumption is high, and the count value is a predetermined value. An image forming apparatus that reduces the temperature of the toner layer on the developing roller by executing a series of image forming operations after the rotation of the developing roller is stopped for a predetermined time when the value is equal to or greater than the reference value is disclosed.

However, in the conventional image forming apparatus that performs in-machine cooling using a cooling fan or a duct, the temperature within the image forming apparatus that can be reduced is limited due to restrictions on the size, configuration, layout, and the like of the main body of the image forming apparatus.
Also, depending on the location where the temperature rise in the conventional image forming apparatus becomes a problem, the temperature at that location may not be directly monitored and the temperature may not be controlled. In particular, when an image forming unit having a developing device is continuously driven for a long time, the temperature of a sliding portion such as a bearing in the developing device and the temperature of the developer itself are considerably increased, and the developer in the developing device is increased. Although the (toner) may melt, it is difficult to directly monitor the temperature of the sliding portion and the temperature of the developer itself.
Further, in the image forming apparatus of the above cited reference 1, it is not possible to prevent toner melting due to an excessive increase in the temperature of the toner on the developing roller in the developing device.
Further, in the image forming apparatus of the above cited reference 2, when the number of dots of the toner image is small, the temperature of the sliding part such as the bearing part of the developing roller and the developer in the developing apparatus is considerably increased. The problem that the toner melts in the inside cannot be solved.

  Therefore, the present applicant detects the temperature inside or around the developing device that changes in accordance with the temperature of the developer carrying member, and limits the number of pages that can be continuously imaged and the limitation based on the detection result. Proposed an image forming apparatus that controls the release of the image (see Patent Document 3). According to this image forming apparatus, the developer on the developer carrying member while avoiding a decrease in efficiency during the continuous image forming operation without performing an operation for estimating the temperature of the developer carrying member or developer in the developing device. It is possible to prevent melting due to excessive temperature rise.

  The present invention aims to further improve the image forming apparatus according to the above proposal. That is, the present invention eliminates the excess of the developer on the developer carrier while avoiding a decrease in efficiency during the continuous image forming operation without performing an operation for estimating the temperature of the developer carrier and the developer in the developing device. An object of the present invention is to provide an image forming apparatus that can more reliably prevent melting due to temperature rise.

  To achieve the above object, the present invention provides a latent image forming means for forming a latent image on an image carrier and a developing device for developing the latent image on the image carrier by a developer carried on the developer carrier. And an image forming apparatus capable of continuously executing image forming operations on a plurality of pages, and detecting a temperature inside or around the developing apparatus that changes in accordance with a temperature of the developer carrying member. Detecting means provided at a plurality of locations of the image forming apparatus, and control means for controlling the restriction on the number of pages that can be continuously imaged and the release of the restriction based on the detection results of the temperature detecting means at the plurality of locations. It is characterized by having.

In the present invention, the temperature inside or around the developing device that changes corresponding to the temperature of the developer carrying member is detected, and based on the detection result, the number of pages on which continuous image formation is possible and the restriction are released. Control. Here, when it is determined that the developer carrier is excessively heated based on the detection result, the operation of the developer carrier is suspended by limiting the number of pages on which continuous image formation is possible. An excessive temperature rise of the developer carrier can be prevented. Therefore, melting of the developer on the developer carrying member due to excessive temperature rise can be prevented.
If it is determined that the temperature of the developer carrier is not excessively high based on the detection result, the operation of the developer carrier is suspended by releasing the restriction on the number of pages on which continuous image formation is possible. The image forming operation can be continuously executed without causing the image forming operation to occur. Accordingly, it is possible to avoid a decrease in efficiency during the continuous image forming operation.
In addition, because the above-described limitation on the number of pages that can be formed with continuous images and the control for releasing the limitation are based on the detection result of the temperature inside or around the developing device that changes in accordance with the temperature of the developer carrier. Therefore, it is not necessary to perform an operation for estimating the temperature of the developer carrying member or developer in the developing device.
Further, the temperature inside or around the developing device that changes corresponding to the temperature of the developer carrying member is detected at a plurality of locations in the image forming apparatus. Based on the detected temperatures measured at a plurality of locations, it is determined whether or not the temperature distribution in the image forming apparatus is a target temperature distribution preliminarily assumed in the apparatus design or the like. It is possible to control the restriction and the release of the restriction more appropriately. Therefore, melting of the developer on the developer carrying member due to excessive temperature rise can be prevented more reliably.

1 is a schematic configuration diagram illustrating an overall configuration of a printer that is an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram illustrating a configuration example of a yellow image forming unit used in the printer. FIG. 3 is a perspective view of a yellow image forming unit. FIG. 2 is a functional block diagram illustrating a main configuration of a control system in the printer. The graph which shows an example of the time change of the detection temperature T of the image development unit when the transition control to an intermittent printing operation mode and a normal printing mode is performed. Explanatory drawing of the braking time S between the page number restriction job and the page number restriction job in the intermittent printing operation mode. Explanatory drawing of the airflow in a printer. The graph which shows an example of the temperature change in several places when the airflow as aimed in the printer has generate | occur | produced. The graph which shows an example of the temperature change in several places when the airflow as aimed in the printer has not generate | occur | produced. 6 is a graph showing an example of the correlation between the detected temperature T of the temperature sensor and the actual temperature of the developing unit when there is a finisher and when there is no finisher. 6 is a graph showing an example of a correlation between a detection temperature T of a temperature sensor and an actual temperature of a developing unit in each of a monochrome image formation mode and a full color image formation mode. The graph which shows an example of the correlation with the detection temperature T of the temperature sensor, and the actual temperature of a developing unit in the case where all of the plurality of fans are operated and in the case where some of them are operated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an overall configuration of a printer which is an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a configuration example of a yellow image forming unit 1Y used in the printer. FIG. 3 is a perspective view of the yellow image forming unit 1Y.

  The printer shown in FIG. 1 includes four image forming units 1Y, 1C, 1M, and 1K for generating yellow, magenta, cyan, and black (hereinafter referred to as Y, C, M, and K) toner images. . These image forming units use Y toner, C toner, M toner, and K toner of different colors as image forming substances (developers) for forming an image, but the other configurations are the same. Here, an image forming unit 1Y for generating a Y toner image will be described as an example. As shown in FIG. 2, the image forming unit 1Y includes a photosensitive unit 2Y having a drum-shaped photosensitive member 3Y as a latent image carrier, and a developing unit 7Y as a developing device for developing a latent image on the photosensitive member 3Y. And have. As shown in FIG. 3, the photosensitive unit 2Y and the developing unit 7Y are detachably attached to the printer body as an image forming unit 1Y. However, the developing unit 7Y can be attached to and detached from the photoreceptor unit 2Y in a state where it is detached from the printer body.

  Below the image forming units 1Y, 1C, 1M, and 1K in the drawing, an optical writing unit 20 as a latent image forming unit is disposed. The optical writing unit 20 irradiates the photoconductors 3Y, 3C, 3M, and 3K after the uniform charging of the image forming units 1Y, 1C, 1M, and 1K based on the image information. Thereby, electrostatic latent images for Y, C, M, and K are formed on the photoreceptors 3Y, 3C, 3M, and 3K. In the optical writing unit 20, the laser light L emitted from the light source is deflected by the polygon mirror 21 that is rotationally driven by a motor, and the photoreceptors 3Y, 3C, 3M, and 3K are passed through a plurality of optical lenses and mirrors. Is irradiated. Instead of such a configuration, it is also possible to employ one that performs optical scanning with an LED array.

  In FIG. 1, below the optical writing unit 20, a first paper feed cassette 31 and a second paper feed cassette 32 that supply recording paper P as a recording medium are arranged so as to overlap in the vertical direction. Each of these paper feed cassettes stores a plurality of recording papers P, which are recording media, in a bundle of recording papers. The uppermost recording paper P includes a first paper feed roller 31a, The second paper feed rollers 32a are in contact with each other. When the first paper feed roller 31a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost recording paper P in the first paper feed cassette 31 is vertical on the right side of the cassette in the figure. The paper is discharged toward a paper feed path 33 arranged to extend in the direction. When the second paper feed roller 32a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost recording paper P in the second paper feed cassette 32 is directed toward the paper feed path 33. Discharged. A plurality of transport roller pairs 34 are arranged in the paper feed path 33, and the recording paper P fed into the paper feed path 33 is sandwiched between the rollers of the transport roller pair 34 while being fed between the paper feed paths 33. 33 is conveyed from the lower side to the upper side in the figure.

  A registration roller pair 35 is disposed at the end of the paper feed path 33. The registration roller pair 35 temporarily stops the rotation of both rollers as soon as the recording paper P sent from the conveyance roller pair 34 is sandwiched between the rollers. Then, the recording paper P is sent out to a secondary transfer nip described later at an appropriate timing.

  Above each of the image forming units 1Y, 1C, 1M, and 1K, a transfer unit 40 is disposed as a transfer unit that is endlessly moved counterclockwise in the drawing while stretching an intermediate transfer belt 41 as an intermediate transfer member. It is installed. In addition to the intermediate transfer belt 41, the transfer unit 40 includes a belt cleaning unit 42, a first bracket 43, a second bracket 44, and the like. Also provided are four primary transfer rollers 45Y, 45C, 45M, 45K, a secondary transfer backup roller 46, a drive roller 47, an auxiliary roller 48, a tension roller 49, and the like. The intermediate transfer belt 41 is endlessly moved in the counterclockwise direction in the figure by the rotational drive of the drive roller 47 while being stretched around these eight rollers. The four primary transfer rollers 45Y, 45C, 45M, and 45K sandwich the intermediate transfer belt 41 that moves endlessly between the photoreceptors 3Y, 3C, 3M, and 3K to form primary transfer nips. Then, a transfer bias having a polarity opposite to that of the toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 41. The intermediate transfer belt 41 passes through the primary transfer nips for each of the colors Y, C, M, and K in accordance with the endless movement of the intermediate transfer belt 41, and on the photoreceptor 3Y, 3C, 3M, 3K on the front surface. The Y toner image, the C toner image, the M toner image, and the K toner image are primarily transferred so as to overlap each other. As a result, a four-color superimposed toner image (hereinafter referred to as “four-color toner image”) is formed on the intermediate transfer belt 41.

  The secondary transfer backup roller 46 constituting the secondary transfer means sandwiches the intermediate transfer belt 41 with the secondary transfer roller 50 disposed outside the loop of the intermediate transfer belt 41 to form a secondary transfer nip. ing. The registration roller pair 35 feeds the recording paper P sandwiched between the rollers toward the secondary transfer nip at a timing to synchronize with the four-color toner image on the intermediate transfer belt 41. The four-color toner image on the intermediate transfer belt 41 is affected by the secondary transfer electric field formed between the secondary transfer roller 50 to which the secondary transfer bias is applied and the secondary transfer backup roller 46, and the influence of the nip pressure. Then, the secondary transfer is collectively performed on the recording paper P in the secondary transfer nip. Then, combined with the white color of the recording paper P, a full color toner image is obtained.

  The residual transfer toner remaining on the intermediate transfer belt 41 without being transferred to the recording paper P even after passing through the secondary transfer nip is cleaned by the belt cleaning unit 42. The belt cleaning unit 42 makes the cleaning blade 42a abut against the front surface of the intermediate transfer belt 41, thereby scraping off and removing the transfer residual toner on the belt.

  A fixing unit 60 as a fixing unit for fixing the toner image on the recording paper P is disposed above the secondary transfer nip in the figure. The fixing unit 60 includes a pressure heating roller 61 that includes a heat source such as a halogen lamp, and a fixing belt unit 62. The fixing belt unit 62 includes a fixing belt 64 as a fixing member, a heating roller 63 containing a heat source 63a such as a halogen lamp, a tension roller 65, a driving roller 66, and the like. Then, the endless fixing belt 64 is endlessly moved in the counterclockwise direction in the drawing while being stretched by the heating roller 63, the tension roller 65, and the driving roller 66. In the process of endless movement, the fixing belt 64 is heated from the back side by the heating roller 63. A pressure heating roller 61 that is driven to rotate in the clockwise direction in the drawing is in contact with the surface of the fixing belt 64 that has been heated in this manner. Thereby, a fixing nip where the pressure heating roller 61 and the fixing belt 64 abut is formed.

  Outside the loop of the fixing belt 64, a temperature sensor (not shown) is disposed so as to face the front surface of the fixing belt 64 with a predetermined gap, and the fixing belt 64 just before entering the fixing nip. Detect the surface temperature of. The detection result is sent to a fixing power supply circuit (not shown). The fixing power supply circuit performs on / off control of power supply to the heat source 63 a included in the heating roller 63 and the heat source 61 a included in the pressure heating roller 61 based on the detection result by the temperature sensor. Thereby, the surface temperature of the fixing belt 64 is maintained at about 140 ° C., for example.

  The recording paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 41 and then fed into the fixing unit 60. Then, in the process of being conveyed from the lower side to the upper side in the figure while being sandwiched between the fixing nips in the fixing unit 60, the full-color toner image is heated and pressed by the fixing belt 64 and the pressure heating roller 61. Is established.

The recording paper P subjected to the fixing process in this manner is discharged outside the apparatus after passing between the rollers of the paper discharge roller pair 67. A stack unit 68 is formed on the upper surface of the housing of the printer main body, and the recording paper P discharged to the outside by the discharge roller pair 67 is sequentially stacked on the stack unit 68.
Above the transfer unit 40, four toner cartridges 100Y, 100C, 100M, and 100K that store Y toner, C toner, M toner, and K toner are disposed. Each color toner in the toner cartridges 100Y, 100C, 100M, and 100K is appropriately supplied to the developing units 7Y, 7C, 7M, and 7K of the image forming units 1Y, 1C, 1M, and 1K. The toner cartridges 100Y, 100C, 100M, and 100K are detachable from the printer main body independently of the image forming units 1Y, 1C, 1M, and 1K.

  In FIG. 2, the photoconductor unit 2Y includes a photoconductor 3Y, a drum cleaning device 4Y, a static eliminator (not shown), a charging device 5Y as a charging unit for charging the surface of the photoconductor 3Y, and the like. The charging device 5Y uniformly charges the surface of the photoreceptor 3Y that is driven to rotate in the clockwise direction in the drawing by a driving unit (not shown). In the configuration example of FIG. 2, the charging roller 6 </ b> Y that is driven to rotate counterclockwise in the drawing is brought close to the photoconductor 3 </ b> Y while a charging bias is applied by a power source (not shown), thereby uniformly charging the photoconductor 3 </ b> Y. A charging device 5Y of the type is shown. Instead of the charging roller 6Y, a roller that contacts a charging brush may be used. Moreover, you may use what charges the photoreceptor 3Y uniformly by a charger system like a scorotron charger. The surface of the photoreceptor 3Y uniformly charged by the charging device 5Y is exposed and scanned by a laser beam emitted from the optical writing unit 20 to carry an electrostatic latent image for Y.

  The developing unit 7Y has a first agent accommodating portion 9Y in which a first conveying screw 8Y is disposed. Further, a toner concentration sensor 10Y including a magnetic permeability sensor as a toner concentration detecting unit, a second conveying screw 11Y, a developing roller 12Y as a developer carrying member, a doctor blade 13Y as a developer regulating member, and the like are provided. It also has a second agent storage portion 14Y. In these two agent storage portions 9Y and 14Y, a Y developer (not shown) having a magnetic carrier and a negatively chargeable Y toner is included. The first transport screw 8Y is rotationally driven by a driving unit (not shown) and transports the Y developer in the first agent storage portion 9Y from the near side to the far side in the direction perpendicular to the paper surface. Then, the Y developer is caused to enter the second agent accommodating portion 14Y through a communication port (not shown) provided in the partition wall between the first agent accommodating portion 9Y and the second agent accommodating portion 14Y.

  The second conveying screw 11Y in the second agent accommodating portion 14Y is rotationally driven to convey the Y developer from the back side to the near side in the drawing. The Y developer during conveyance is detected by the toner concentration sensor 10Y fixed to the bottom of the first agent storage portion 14Y. Above the second conveying screw 11Y, a developing roller 12Y is disposed in parallel with the second conveying screw 11Y. The developing roller 12Y includes a magnet roller 16Y in a developing sleeve 15Y made of a non-magnetic pipe that is driven to rotate counterclockwise in the drawing. A part of the Y developer conveyed by the second conveying screw 11Y is pumped up to the surface of the developing sleeve 15Y by the magnetic force generated by the magnet roller 16Y. Then, after the layer thickness is regulated by the doctor blade 13Y disposed so as to maintain a predetermined gap from the developing sleeve 15Y, the layer thickness is regulated and conveyed to the developing area facing the photosensitive member 3Y, and the Y for the photosensitive member 3Y is used. Y toner is adhered to the electrostatic latent image. This adhesion forms a Y toner image on the photoreceptor 3Y. The Y developer that has consumed Y toner by development is returned to the second conveying screw 11Y as the developing sleeve 15Y rotates. And if it conveys to the front end in a figure, it will return in the 1st agent accommodating part 9Y through a communication port not shown.

  The result of detecting the magnetic permeability of the Y developer by the toner concentration sensor 10Y is sent as a voltage signal to a control unit (not shown). Since the magnetic permeability of the Y developer shows a correlation with the Y toner density of the Y developer, the toner density sensor 10Y outputs a voltage having a value corresponding to the Y toner density. The control unit includes a memory such as a RAM as storage means. In this memory, Y Vtref which is a target value of the output voltage from the toner density sensor 10Y, C Vtref which is a target value of the output voltage from each toner density sensor mounted in another developing unit, and Vtref for M , K Vtref data is stored. For the Y developing unit 7Y, the value of the output voltage from the toner density sensor 10Y is compared with the Y Vtref, and the Y toner supply device described later is driven for a time corresponding to the comparison result. By this driving, an appropriate amount of Y toner is supplied to the first developer containing portion 9Y with respect to the Y developer whose Y toner density has been reduced by consumption of the Y toner during development. For this reason, the Y toner density in the second agent container 14Y is maintained within a predetermined range. The same toner supply control is performed for the developers in the image forming units (1C, 1M, 1K) for other colors.

The Y toner image formed on the photoreceptor 3Y is intermediately transferred to the intermediate transfer belt 41. The drum cleaning device 4Y removes the toner remaining on the surface of the photoreceptor 3Y after the intermediate transfer process. As a result, the surface of the photoreceptor 3Y subjected to the cleaning process is neutralized by a neutralization device (not shown). By this charge removal, the surface of the photoreceptor 3Y is initialized and prepared for the next image formation.
In FIG. 1, in the image forming units 1C, 1M, and 1K for other colors, C toner images, M toner images, and K toner images are similarly formed on the photoreceptors 3C, 3M, and 3K, and the intermediate transfer belt 41 is formed. Intermediate transfer is performed on the top.

  In the printer having the above-described configuration, a temperature sensor (not shown) serving as a temperature detection unit is a detection temperature having a high correlation with the position in the development unit 7Y or in the vicinity of the development unit 7Y in the image forming apparatus body, that is, the development unit internal temperature. It is installed at the position. This temperature sensor detects the temperature inside or around the developing device that changes corresponding to the temperature of the developing sleeve 15Y. The other color image forming units have the same configuration.

  FIG. 4 is a functional block diagram showing the main configuration of the control system in the printer having the above configuration. In FIG. 4, a control unit 900 as a control unit includes, for example, a CPU, a ROM, a RAM, and the like. The control unit 900 is connected to a storage unit 901 as a storage unit, an operation unit 902 as an input unit, an I / O board 903 as a temperature detection interface unit, a development drive motor driver 904 as a developer carrier driving unit, and the like. ing. Based on an instruction from the control unit 900, the I / O board 903 detects a temperature by a temperature sensor 905 serving as a temperature detection unit provided in the developing unit 7 or in the vicinity of the developing unit 7 in the image forming apparatus main body. Let the action take place. Then, the I / O board 903 converts the voltage (detection voltage) of the temperature detection signal of the temperature sensor 905 into a digital signal and sends it to the control unit 900. The development drive motor driver 904 supplies a predetermined voltage or current to the development drive motor 906 that is a drive source of the development roller 12 based on an instruction from the control unit 900. Further, the development drive motor driver 904 rotates the developing sleeve 15 of the developing roller 12 at a predetermined rotational speed or turns on / off the rotation based on an instruction from the control unit 900. The storage unit 901 includes, for example, a memory made of a semiconductor, a magnetic disk, an optical disk, and the like, and stores data of a detected temperature detected by the temperature sensor 905, and various control conditions such as temperature thresholds T1 and T2 described later. Store the setting data. Data in the storage unit 901 can be written or read from the control unit 900.

  The operation unit 902 includes, for example, various buttons and patch panels that can be operated by the user, a liquid crystal display as a display unit, and the like, and also functions as an input unit for inputting various control conditions. Various data input and set by the user operating the operation unit 902 are stored in the storage unit 901 via the control unit 900 and can be used for control. The operation unit 902 also functions as a notification unit that notifies time information when an operation (intermittent printing operation mode) for limiting the number of pages that can be formed with a continuous image, which will be described later, is executed.

  In addition, the printer according to the present embodiment includes a temperature information acquisition unit that acquires information on the outside air temperature outside the printer. This temperature information acquisition means can be configured using, for example, a temperature sensor (not shown) provided outside the printer and connected to the control unit 900. Data on the outside air temperature detected by this temperature sensor can be stored in the storage unit 901. The temperature information acquisition unit may be configured using a communication interface unit that receives outside temperature data from an external storage medium via communication, or an operation unit 902 that allows a user to input outside temperature data. You may comprise using.

  The control unit 900 can be configured by a general-purpose microcomputer, for example. Further, all or a part of the control unit 900 may be configured by an integrated circuit element (for example, an IC) designed to perform control and processing described later.

The control unit 900 can execute various controls and processes as shown in the following (1) to (6) by reading and executing a predetermined control program.
(1) Instruction for driving developing roller (2) Calculation of detected temperature from detection voltage data of temperature sensor (3) Judgment and execution of transition to later-described intermittent printing operation mode (4) To intermittent printing operation mode described later (5) Switching of temperature threshold T1 in intermittent printing operation mode described later (6) Switching of temperature threshold T2 in intermittent printing operation mode described later

Next, an example of operation mode control based on the detected temperature in the printer having the above configuration will be described.
In the control example of the printer according to the present embodiment, the control unit 900 controls the operation mode as described below based on the detected temperature that is the detection result of the temperature sensor 905 and the preset temperature thresholds T1 and T2. .
First, the control unit 900 instructs the developing roller to be driven, and converts the detected voltage detected by the temperature sensor 905 into a temperature. Data of the temperature value of this conversion result (assuming T [° C.]) is stored in the storage unit 901. When the data of the detected temperature T is stored, the current detected temperature T is compared with a preset first temperature threshold T1 stored in the storage unit 901. Here, when T ≧ T1, a limited image forming operation mode (hereinafter referred to as “intermittent printing operation mode” or “in-machine cooling mode”) in which the number of pages on which continuous image formation is possible is limited to a predetermined number L or less. Control to shift to. In this intermittent printing operation mode, even if a print request for a continuous printing operation (image forming operation) of the total page number Li (> L) is instructed, the developing roller 12 is included for a predetermined time R every predetermined page number L. The developing unit 7 stops and enters a standby state for the image forming operation. That is, the continuous printing operation (continuous image forming operation) of the plurality of pages Li for which the instruction is given is intermittently executed for each predetermined page L set in advance.

  After shifting to the intermittent printing operation mode, the control unit 900 compares the current detected temperature T with a preset second temperature threshold T2 (<T1) stored in the storage unit 901. Here, when T <T2, the restriction on the number of pages L on which continuous image formation is possible is released, and a normal image forming operation mode (hereinafter referred to as “continuous image forming operation”) in which continuous printing operation (continuous image forming operation) is possible. Return to “Normal Print Mode”). In this normal printing mode, when a print request for a continuous printing operation (image forming operation) of the total number of pages Li (> L) is instructed, the image formation in which the developing unit 7 stops for a predetermined time every predetermined page number L. There is no waiting for operation. In the normal printing mode, the continuous printing operation (continuous image forming operation) of the plurality of pages Li instructed is executed without entering the standby state of the image forming operation.

  The temperature threshold values T1 and T2 used for determining the transition to the intermittent printing operation mode or the normal printing mode in this control example, and the set value of the number L of pages capable of forming continuous images are stored in the storage unit 901. Yes. The storage unit 901 also stores setting values of control conditions such as the setting value of the shortest stop period R from the stop of driving of the developing roller 12 of the developing unit 7 to the restart of driving in the intermittent printing operation mode.

  Further, the user operates the operation unit 902 to input temperature threshold values T1 and T2, a set value for the number L of pages that can form continuous images, and a set value for control conditions such as the set value for the shortest stop period R. be able to. By this input, the set values of the control conditions such as temperature thresholds T1 and T2 stored in the storage unit 901 are changed to the input set values. As described above, the control conditions such as the temperature thresholds T1 and T2 can be arbitrarily set by operating the operation unit 902. As a result, control conditions such as temperature thresholds T1 and T2 that match the actual usage environment and usage of the printer can be set in the actual usage location and market of the printer. Therefore, it is possible to further reduce the occurrence of problems such as toner melting due to the temperature rise of the developing roller 12, and to minimize the decrease in productivity when printing on recording paper.

FIG. 5 is a graph showing an example of a temporal change in the detected temperature T of the developing unit when the transition control to the intermittent printing operation mode and the normal printing mode is performed.
In FIG. 5, when the temperature T [° C.] detected by the temperature sensor 905 is equal to or higher than the first temperature threshold T1 in the state where the normal printing operation mode capable of continuous printing operation is set, the mode is shifted to the intermittent printing operation mode. To do. Due to the transition to the intermittent printing operation mode, even if the print request is continuous printing with multiple pages (total number of pages Li> L), the intermittent printing operation in which the number of continuous printing pages is limited to L pages is repeated. By doing so, the stop time of the development unit 7 with respect to the total number of printed pages Li is increased, and the temperature of the development unit 7 (development roller 12) can be not increased or decreased any further. Further, by setting the shortest time (standby time) R from the stop of driving of the developing unit 7 to the re-driving at the time of intermittent printing operation (not shown) to an arbitrary value, it is possible to respond to the actual usage environment and usage of the printer. Thus, the temperature of the developing unit 7 can be further controlled.
Thereafter, in the intermittent printing operation mode, when the detected temperature T [° C.] by the temperature sensor 905 becomes lower than the second temperature threshold T2 (<T1), it can be determined that the temperature of the developing unit 7 has sufficiently decreased. Based on this determination, the restriction on the number of continuous printing pages up to that point is canceled, and the normal printing operation mode capable of continuous printing without restriction on the number of continuous printing pages is returned.

  Note that the predetermined number P of continuous print pages in the intermittent print operation mode and the shortest time R from the stop of driving of the developing unit 7 to the re-drive of the developing unit 7 can be actually used by operating the operation unit 902. It may be set to any value according to the environment and usage. In this case, it is possible to further reduce the occurrence of problems due to the temperature rise of the developing roller 12.

  Further, control of temperature threshold values T1 and T2 in the intermittent printing operation mode in the present control example, a predetermined page number L that is a limit value of continuous printing pages, and a minimum time R from the stop of driving of the developing unit 7 to re-driving. The set value of the condition can be set by operating the operation unit 902. That is, these setting values can be set to arbitrary values according to the actual usage environment and usage by operating the operation unit 902. Therefore, it is possible to further reduce the occurrence of problems due to the temperature rise of the developing roller 12 and to minimize the decrease in productivity when printing on recording paper.

  The temperature threshold values T1 and T2 can be set to arbitrary values from the operation unit 902, but the magnitude relationship is preferably T1> T2. Thus, by setting T1> T2, it is possible to prevent the toner in the developing unit 7 from being melted due to continuous printing immediately after the restriction on the number of continuously printed pages is released and the temperature rapidly rising.

Next, the braking time S between print jobs (image forming jobs) limited to a predetermined number P of continuous print pages in the intermittent printing operation mode will be described.
The purpose of the intermittent printing operation is to prevent the temperature of the developing unit 7 from rising by lowering the productivity of the printed recording paper and to lower the temperature of the developing unit 7. In this intermittent printing operation, the number of pages that can be continuously printed is limited to P pages, and a continuous print job for a plurality of pages Pi that has been instructed to be printed is a continuous print job for P pages that is smaller than Pi (hereinafter referred to as “page number limited job”). "). Thereby, a time for stopping the driving of the developing roller 12 of the developing unit 7 is provided, and the temperature of the developing unit 7 can be lowered.

  However, even if the intermittent printing operation mode in which the intermittent printing operation is performed is described, if the time between a plurality of divided page number limiting jobs is short, the preceding page number limiting job ends and then the subsequent page number limiting Job comes. Therefore, immediately after the preceding page limit job ends and the rotation of the various motors as the drive source in the printer stops, the print preparation for executing the subsequent page number limiting job is started, and the various motors start moving. End up. As described above, there may be a case where the motor stop time for rotating the developing roller 12 of the developing unit 7 cannot be secured sufficiently long. In particular, under conditions where the development unit is difficult to cool, such as in a high temperature environment where the outside air temperature is high, it is possible that the temperature rise of the development unit 7 cannot be reliably prevented only by limiting the number of continuously printed pages.

  Therefore, in the present embodiment, as shown in FIG. 6, a predetermined braking time S during which the printing operation (image formation) is not performed is provided between the page number limited job and the page number limited job in the intermittent printing operation mode. So that it is controlled. As a result, the rotation drive of the developing roller 12 of the developing unit 7 can be forcibly stopped, and the temperature of the developing unit 7 can be effectively lowered. The length of the braking time S may be changed based on the outside air temperature.

  Next, control for setting the first temperature threshold value T1 used for determining the transition to the intermittent printing operation mode (in-machine cooling mode) in the printer of the present embodiment will be described. In the present embodiment, the temperature threshold T1 is set based on the detection results of a plurality of temperature sensors.

  In the printer of this embodiment, depending on the user, the apparatus main body may be disposed so as to contact the wall, or an object that obstructs some airflow may be placed near the intake / exhaust port of the apparatus main body. In such a case, for example, there is a possibility that the air current as intended in the apparatus design or the like is not generated in the apparatus main body of the printer. If the air flow as intended is not generated in this way, the temperature distribution in the printer main body does not become the target temperature distribution assumed in the apparatus design or the like, and the temperature in the main body of the apparatus may rise rapidly. Furthermore, there is a possibility that the temperature balance between the temperature sensor 905 provided in the vicinity of the developing unit 7 and the developing unit 7 may be lost due to a change in the air flow in the printer main body. In this case, the predicted temperature of the developing unit 7 obtained based on the temperature detected by the temperature sensor 905 deviates from the actual temperature of the developing unit 7, and erroneously detects the temperature that shifts to the intermittent printing operation mode that restricts the printing operation. May end up.

  Therefore, in this embodiment, temperature sensors are installed at a plurality of different locations (for example, at least two locations). Based on the detection results of the temperature sensors at the multiple locations, the temperature distribution in the printer is the target temperature distribution from the balance of the detection temperatures of those temperature sensors, that is, the airflow in the printer flows as intended. Judgment is made. Based on this determination result, a first temperature threshold T1 used for determining the transition to the intermittent printing operation mode is set. Accordingly, it is possible to appropriately shift to the intermittent printing operation mode and prevent the developing unit from becoming high temperature. Hereinafter, a more specific configuration will be described.

  FIG. 7 is an explanatory diagram of airflow in the printer of this embodiment. In the printer of this embodiment, in order to cool the internal temperature during continuous operation, an intake fan is disposed at a position 70 in FIG. 7 and an exhaust fan is disposed at a position 71 in FIG. Accordingly, as shown by the gray arrow in FIG. 7, the yellow image forming unit (hereinafter referred to as “yellow station”) 1Y to the black image forming unit (hereinafter referred to as “black station”) 1K from 1Y. Intentionally creating a crossing airflow. This airflow cools the inside of the printer.

  Here, the transition of the temperature detected by the temperature sensor 905 and the temperature of the developing unit 7 when the printer of this embodiment is continuously operated in a high temperature environment will be described.

FIG. 8 is a graph showing an example of a temperature rise profile when the printer is continuously operated in a high temperature environment under normal conditions in which a target airflow is generated in the printer of this embodiment.
“Unit 1” in FIG. 8 is the black developing unit 7K, and the profile of “Unit 1 temperature” in the drawing shows the change over time of the actual temperature of the developing unit 7K. In addition, the profile of “unit 1 temperature sensor” in the drawing indicates the time change of the first detected temperature detected by the first temperature sensor 905K disposed in the vicinity of the developing unit 7K.
Further, “unit 2” in FIG. 8 is a yellow developing unit 7Y, and the profile of “unit 2 temperature” in the drawing shows a change with time of the actual temperature of the developing unit 7Y. In addition, the profile of “unit 2 temperature sensor” in the drawing indicates the time change of the second detected temperature detected by the second temperature sensor 905Y disposed in the vicinity of the developing unit 7Y.

  Further, the profile of “environmental sensor” in FIG. 8 shows a change over time in the detected temperature of a temperature sensor (for example, a temperature sensor provided outside the printer) that detects the outside air temperature.

  Under the normal conditions of FIG. 8, the detected temperature (“unit 1 temperature sensor” in the figure) detected by the first temperature sensor 905K is the detected temperature (in the figure) detected by the second temperature sensor 905Y. "Unit 2 temperature sensor"). That is, the temperature at the black station 1K is higher than the temperature at the yellow station 1Y. This is because the air flow in the printer is generated so as to flow from the yellow station 1Y toward the black station 1K as shown in FIG. That is, the yellow station 1Y located on the upstream side in the airflow direction is blown with the outside air sucked by the fan, and therefore has a lower temperature than the black station 1K.

  Further, a temperature difference occurs between the temperature sensor 905 and the developing unit 7 as follows. During operation of the printer, a screw and a developing roller (developing sleeve) 12 are rotated at high speed in the developing unit 7. For this reason, the screw and the bearing of the developing roller 12 serve as a heat source, and the developer in the developing unit 7 is warmed to a high temperature. On the other hand, the temperature sensor 905 is installed outside the developing unit 7 and does not receive heat directly from a high-temperature member such as the screw or the bearing of the developing roller 12. Therefore, the temperature sensor 905 has the same temperature as the ambient temperature near the developing unit. As described above, the temperature of the temperature sensor 905 is lower than that of the developing unit 7 when the printer is in operation.

  In the printer showing the temperature transition shown in FIG. 7, for example, as shown below, the first temperature threshold value T1 used to determine the transition to the intermittent printing operation mode (in-machine cooling mode) is determined and set. For example, when it is desired to keep the developing unit 7 below 53 [° C.] in FIG. 7, the black station 1K is always higher than the temperature of the yellow station 1Y, and therefore the black station 1K is controlled not to exceed 53 [° C.]. Good. In this case, the temperature sensor 905K in the vicinity of the black station 1K may be controlled so as not to exceed 50 [° C.]. That is, when one of the two temperature sensors 905K and 905Y reaches 50 [° C.], control is performed so as to shift to an intermittent printing operation mode that restricts productivity.

  Next, a description will be given of a temperature rise when the printer is continuously operated in a high-temperature environment under conditions where the airflow in the printer of the present embodiment is not as intended. The condition where the airflow is not as intended is a wall-side installation condition in which the printer is installed such that the position of the intake port (see reference numeral 70 in FIG. 7) where the intake fan of the printer is intentionally placed is in close contact with the wall.

  FIG. 9 is a graph showing an example of a temperature rise profile when the printer is continuously operated in a high temperature environment under a wall-side installation condition in which no target airflow is generated in the printer of this embodiment. In this case, an air current as shown by the gray arrow in FIG. 7 described above is not generated. Therefore, as shown in FIG. 9, the temperature rise of the developing unit 7 is very fast. Further, the yellow station 1Y and the black station 1K draw a temperature rise curve having substantially the same profile. The developing units 7Y and 7K of the yellow station 1Y and the black station 1K have their driving sources as heat sources and the temperature rises. In addition, since there is no air flow in the printer main body, the cooling path for cooling each developing unit is considered to be the same. The temperature sensor 905 also eliminates the temperature difference between stations. However, since there is no heat source like the developing unit 7, the temperature is lower than that of the developing unit 7.

As described above, when the target airflow assumed in the apparatus design or the like is not generated in the printer, the temperature of the developing unit 7 rapidly increases. Further, the correlation between the temperature of the temperature sensor 905 and the temperature of the developing unit 7 changes. Therefore, there is a possibility that the temperature for shifting to the intermittent printing operation mode that restricts the printing operation is not appropriate.
For example, under the normal conditions shown in FIG. 8, one of the first temperature sensor 905K and the second temperature sensor 905Y is 50 [° C.] so that the developing unit 7 does not exceed 53 [° C.]. Is reached, the mode shifts to an intermittent printing operation mode that restricts productivity.
On the other hand, under the wall-side installation conditions shown in FIG. 9 described above, when one of the temperature sensors 905K and 905Y reaches 50 [° C.], control is performed so as to shift to an intermittent printing operation mode that restricts productivity. 7 is 58 [° C.]. That is, the temperature of the developing unit 7 becomes 5 [° C.] higher than the normal condition of FIG. For this reason, when the target airflow does not flow properly in the printer, the temperature distribution in the printer is determined based on the detection results of the temperature sensors 905K and 905Y, and the temperature T1 that restricts the printing operation is appropriately set. Must be set.
Moreover, it has been found from the results described with reference to FIGS. 7 to 9 that the temperature difference (temperature distribution) between the stations varies depending on the strength and presence of the airflow in the printer. In particular, it was found that the temperature difference between stations tends to be smaller as the airflow in the printer is weaker.

Therefore, in the present embodiment, control is performed so as to obtain the value ΔT of the detected temperatures of the temperature sensors 905K and 905Y and to set the temperature threshold T1 as shown in Table 1 according to the value of the difference ΔT.

  As described above, in the description using FIGS. 7 to 9, the example in which the temperature sensors are installed at two different places is illustrated, but the present invention can also be applied to the case where the temperature sensors are installed at three or more different places.

  Next, control for switching between the first temperature threshold value T1 and the second temperature threshold value T2 used for determining the transition between the normal printing mode and the intermittent printing operation mode (internal cooling mode) will be described.

  For example, the control of further switching the value of the temperature threshold value T1 that is changed according to the detected temperature difference ΔT between the temperature sensors 905K and 905Y depending on the presence and usage of peripheral devices in the printer of this embodiment may be performed. Good. The relationship between the temperature of the developing unit 7 depending on the presence or absence of peripheral devices and how it is used and the detected temperature T detected by the temperature sensor 905 can be approximated by a straight line. Accordingly, a final temperature threshold value obtained by correcting the temperature threshold value T1 set in accordance with the value of the detected temperature difference ΔT by the correction amount of the temperature threshold value T1 corrected according to the presence / absence of the peripheral device described below and how it is used. It may be T1. In this case, the transition to the intermittent printing operation mode (in-machine cooling mode) can be controlled with higher accuracy. Here, the value of the temperature threshold T2 may be switched in accordance with the switching of the temperature threshold T1 (the same applies to the temperature threshold switching control described below).

  The temperature sensor 905 measures the temperature of the inside of the developing unit 7 and the developer. However, since the developing unit 7 is a part that is a replacement part, the temperature sensor 905 is often attached to the apparatus main body near the developing unit 7. . When the distance between the temperature sensor 905 and the developing unit 7 is large, the temperature T detected by the temperature sensor 905 and the developing unit 7 are affected by various factors such as the airflow around the temperature sensor and the set temperature of the heat source such as the run mode and fixing. The correlation with the actual temperature changes. For this reason, the actual temperature of the developing unit 7 may not be obtained uniformly from the detected temperature T of the temperature sensor 905. There is also a measurement error of the temperature sensor 905 itself. For example, when the temperature sensor 905 is a sensor that detects a temperature by a resistance change, if an error occurs in the resistance, a measurement error of the temperature sensor 905 occurs. For these errors, it is necessary to provide a design margin for the temperature threshold T1, and the intermittent printing operation mode (in-machine cooling mode) must be started from a temperature lower than the target temperature threshold T1, resulting in a decrease in productivity. Resulting in. Therefore, in order to minimize the decrease in productivity, the measurement error of the temperature sensor 905 must be reduced.

  Therefore, in the present embodiment, conditions for changing the correlation between the detected temperature T of the temperature sensor 905 and the temperature of the developing unit 7 (for example, presence / absence of a peripheral device, run mode, airflow around the temperature sensor, fixing of a heat source such as fixing) The set temperature may be determined. Then, based on the determination result of the condition, the correlation coefficient (coefficient in the approximate expression) between the detected temperature T of the temperature sensor 905 and the temperature of the developing unit 7 may be changed. In this case, the temperature of the developing unit 7 can be measured more accurately by the temperature sensor 905. The “run mode” is various operation modes having different sheet passing conditions. For example, the run mode includes a single-sided printing mode and a double-sided printing mode, a multi-page continuous paper feeding mode and a multi-page paper feeding mode in which the number of sheets for each print job is different from each other, and an FC mode and a BW mode.

  For example, when a peripheral device (for example, a finisher that processes the recording paper P after image formation) is mounted in the printer of the present embodiment, the airflow in the printer body may be blocked, and the airflow in the printer body may be blocked. It may change. Such a change in the airflow affects the correlation between the temperature T detected by the temperature sensor 905 and the actual temperature of the developing unit 7.

  FIG. 11 is a graph showing an example of the correlation between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 when the printer of the present embodiment has and does not have a finisher as a peripheral device. As shown in FIG. 11, the correlation between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 is greatly different between the case with the finisher and the case without the finisher. In the printer of the model having the characteristics shown in FIG. 11, it is possible to prevent the developing unit 7 from reaching 60 ° C., as exemplified in the following Examples 1 and 2.

(Example 1) When the presence or absence of a finisher is not considered
As shown in FIG. 11, when the temperature of the developing unit 7 is 60 [° C.], the value of the detected temperature T of the temperature sensor 905 is 54 [° C.] to 62 [° C.] depending on the presence or absence of the finisher. When the value of the temperature T detected by the temperature sensor 905 reaches 54 [° C.] when there is no finisher, the temperature of the developing unit 7 is increased unless the above-described intermittent printing operation mode (internal cooling mode) is executed. The temperature does not fall below 60 [° C.]. Therefore, control for shifting to the intermittent printing operation mode for lowering the temperature of the developing unit 7 must be started. On the other hand, if the detected temperature T of the temperature sensor 905 reaches 54 [° C.] when there is a finisher, the actual temperature of the developing unit 7 is only 52 [° C.], and the production is wasted by 8 [° C.]. I will lose my sex.

(Example 2) When considering the presence or absence of a finisher
The correlation data of FIG. 11 is linearly approximated, and a linear approximation expression is obtained according to the presence / absence of the finisher as shown in the following Expression 1 and Expression 2. Here, x in the formula is the temperature of the developing unit 7, and y is the temperature detected by the temperature sensor 905.
With finisher: y = a′x + b ′ (Formula 1)
Without finisher: y = ax + b (Formula 2)

When the temperature of the developing unit 7 is controlled at 60 ° C. or less, the following equations 3 and 4 are obtained.
With finisher: y ′ = a ′ × 60 [° C.] + B ′ (Formula 3)
Without finisher: y ″ = a × 60 [° C.] + B (Formula 4)

  When the finisher is present, the value y ′ in the above equation 3 is set to the temperature threshold T1. On the other hand, when there is no finisher, the value of y ″ in Equation 4 is set as the temperature threshold value T1.

  Specifically, when the respective values of y ′ and y ″ are read from the graph of FIG. 11, they are 62 [° C.] and 54 [° C.]. Therefore, the value of the first temperature threshold value T1 is set to 62 [° C.] when the finisher is present, and is set to 54 [° C.] when the finisher is not present.

  As described above, in the case of Example 2, the measurement error of the temperature sensor 905 due to the presence or absence of the finisher (peripheral machine) can be significantly reduced as compared with the case of Example 1. As described above, a plurality of candidate values are set in advance as the temperature threshold T1, and the plurality of candidate values are switched and used depending on the presence or absence of the finisher (peripheral machine), thereby reducing the measurement error of the temperature sensor 905. it can. Note that the temperature threshold T2 may be switched together with the temperature threshold T1.

  FIG. 12 shows the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 in the monochrome image formation mode (monochrome mode, black toner mode) and full color image formation mode (full color mode) of the printer of this embodiment. It is a graph which shows an example of correlation. Usually, the full-color image formation mode (hereinafter referred to as “FC mode”) has a higher fixing temperature and the number of drive motors than the monochrome image formation mode (hereinafter referred to as “BW mode”). The temperature is often high. Therefore, for example, when the ratio of using the BW mode in the most recent image forming operation is high, the temperature threshold T1 is set higher to suppress the transition to the intermittent printing operation mode, thereby preventing the productivity from being lowered. Also, when the ratio of using the FC mode in the most recent image forming operation is high, the temperature threshold T1 is set low to facilitate the transition to the intermittent printing operation mode, thereby reliably preventing an increase in the printer internal temperature.

  In the case of the example in FIG. 12, the correlation between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 is almost the same in the BW mode and the FC mode. Therefore, in such a case, even if the FC mode tends to be higher in temperature, it is not necessary to switch the temperature threshold value T1 between the BW mode and the FC mode. Further, it is not necessary to change the correlation coefficient (approximation coefficient) indicating the correlation between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 between the BW mode and the FC mode.

  Similarly to the case of FIG. 11 described above, the detected temperature T of the temperature sensor 905 is determined by the single-sided image forming operation for forming an image on one side of the recording paper and the double-sided image forming operation for forming images on both sides of the recording paper. The correlation coefficients indicating the correlation with the actual temperature of the developing unit 7 are different from each other. Therefore, in the printer of the present embodiment, the transition timing to the intermittent printing operation mode is determined between the single-sided image forming operation (hereinafter referred to as “single-sided printing mode”) and the double-sided image forming operation (hereinafter referred to as “double-sided printing mode”). The temperature threshold T1 may be switched to change. For example, as in the case of FIG. 11, in the single-sided printing mode, the value of y ′ in the above equation 3 is set to the temperature threshold T1, and in the double-sided printing mode, the y ″ in the above equation 4 is set. Set the value to the temperature threshold T1.

However, the temperature rise of the developing unit 7 varies depending on how much the recording paper for single-sided printing and the recording paper for double-sided printing have been output. Therefore, the temperature threshold value T1 is switched based on the ratio of single-sided image-forming recording paper (single-sided printing rate) or the ratio of double-sided image-forming recording paper (double-sided printing rate) in the image forming operation of the most recent predetermined number of recording papers. May be. For example, the double-sided printing rate a [%] is obtained for the latest 1000 sheets of recording paper, and y ′ ″ expressed by the following equation 5 is obtained using the double-sided printing rate a [%]. The value of 'is set to the temperature threshold value T1.
y ′ ″ = ((100−a) / 100) × y ′ + (a / 100) × y ″ (Expression 5)

  FIG. 13 shows an example of the correlation between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7 when the plurality of fans provided in the printer of the present embodiment are all operated and when a part is operated. It is a graph to show. When the distance between the temperature sensor 905 in the printer and the developing unit 7 is large, the airflow in the printer changes depending on the number of fans that are operating among a plurality of fans that generate airflow in the printer. Such a change in the airflow affects the correlation (correlation coefficient) between the detected temperature T of the temperature sensor 905 and the actual temperature of the developing unit 7. Since the temperature correlation (correlation coefficient) varies depending on the contents of the fan operation control, the temperature threshold value T1 used for determining the transition timing to the intermittent printing operation mode is switched based on the number of operating fans. May be.

  Also, the airflow in the printer may change depending on the rotational speed of the operating fan. Therefore, the temperature threshold value T1 used for determining the transition timing to the intermittent printing operation mode may be switched based on the rotational speed of the operating fan.

  The airflow in the printer may change depending on the surface moving speed (linear speed) of the photosensitive member 3 as an image carrier and the surface moving speed (linear speed) of the developing roller 12 as a developer carrier. Accordingly, the temperature threshold value T1 used for determining the transition timing to the intermittent printing operation mode is switched based on at least one of the surface moving speed (linear speed) of the photoconductor 3 and the surface moving speed (linear speed) of the developing roller 12. Also good.

  In the above embodiment, the above control examples may be combined as appropriate. For example, the correlation (correlation coefficient) data is acquired in advance for each combination of control examples, and a plurality of sets of threshold values T1 and T2 are stored as a table for each combination. , T2 may be selected and used. Further, when combining the above control examples, the temperature correction rise and fall of various conditions may be simply added together.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A latent image forming unit such as an optical writing unit 20 that forms a latent image on an image carrier such as the photosensitive member 3 and a developer such as toner carried on a developer carrier such as the developing roller 12 on the image carrier. An image forming apparatus, such as a printer, that includes a developing device such as a developing unit 7 that develops a latent image, and that can continuously perform image forming operations on a plurality of pages, and changes in accordance with the temperature of the developer carrier Temperature detecting means such as a temperature sensor 905 for detecting the temperature inside or around the developing device is provided at a plurality of locations of the image forming apparatus, and continuous image formation is possible based on the detection results of the temperature detecting means at the plurality of locations. A control unit such as a control unit 900 that controls the limitation on the number of pages and the release of the limitation, and an operation unit 902 that notifies time information when the operation for limiting the number of pages on which continuous image formation is possible is performed. It includes a notification means.
According to this, as described in the above embodiment, the temperature inside or around the developing device such as the developing unit 7 that changes corresponding to the temperature of the developer carrying member is detected by the temperature detecting means such as the temperature sensor 905. Detect. Based on this detection result, the restriction on the number of pages on which continuous image formation is possible and the release of the restriction are controlled. Here, when it is determined that the developer carrier such as the developing roller 12 is overheated based on the detection result, the developer carrier is controlled by limiting the number of pages on which continuous image formation is possible. It is possible to stop the operation of the developing device, and to prevent the developer carrier from being excessively heated. Therefore, melting of the developer on the developer carrying member due to excessive temperature rise can be prevented. Further, when it is determined that the developer carrier is not overheated based on the detection result, the restriction on the number of pages on which the continuous image can be formed is released. As a result, the image forming operation can be continuously executed without suspending the operation of the developing device including the developer carrying member, so that a reduction in efficiency during the continuous image forming operation can be avoided. In addition, because the above-described limitation on the number of pages that can be formed with continuous images and the control for releasing the limitation are based on the detection result of the temperature inside or around the developing device that changes in accordance with the temperature of the developer carrier. It is not necessary to perform an operation for estimating the temperature of the developer carrier or developer in the developer carrier. Further, the temperature inside or around the developing device that changes corresponding to the temperature of the developer carrying member is detected at a plurality of locations in the image forming apparatus. Based on the detected temperatures measured at the plurality of locations, it is determined whether the temperature distribution in the image forming apparatus is the target temperature distribution, and the number of pages that can be continuously imaged is limited and the restriction is released. It can be controlled properly. Therefore, melting of the developer on the developer carrying member due to excessive temperature rise can be prevented more reliably. Therefore, melting due to excessive temperature rise of the developer on the developer carrier while avoiding a decrease in efficiency at the time of continuous image forming operation without performing calculation for estimating the temperature of the developer carrier or developer in the developing device Can be prevented more reliably, and the image forming operation can be managed by the user.
(Aspect B)
In the aspect A, the control unit such as the control unit 900 can perform continuous image formation on the basis of at least one detection result of the temperature detection unit such as the temperature sensors 905 and a preset temperature threshold. The number threshold is controlled, and the temperature threshold is set based on the detection results of the temperature detection means at the plurality of locations.
According to this, as described in the above embodiment, at least one detection result of a plurality of temperature detection means is compared with the temperature threshold value. Based on this comparison result, limit the number of pages that can form continuous images at different detection temperatures, or limit the number of pages that can form continuous images at multiple detection temperatures that are different from each other. Can do. Moreover, a temperature threshold value is set based on the detection results of the temperature detecting means at the plurality of locations. Accordingly, a criterion for determining whether or not to limit the number of pages on which continuous image formation is possible is set more appropriately depending on whether or not the temperature distribution in the image forming apparatus is a target temperature distribution. be able to.
(Aspect C)
In the above-described aspect A or aspect B, the control unit such as the control unit 900 can generate a continuous image based on at least one detection result of the temperature detection unit such as the temperature sensors 905 at a plurality of locations and a plurality of preset temperature thresholds. The restriction on the number of pages that can be formed and the release of the restriction are controlled, and at least one of the plurality of temperature thresholds is set based on the detection results of the temperature detection means at the plurality of locations.
According to this, as described in the above embodiment, at least one detection result of a plurality of temperature detection means is compared with each of a plurality of temperature thresholds. Based on the result of this comparison, limiting the number of pages that can be formed continuously and releasing the limit are performed at different detection temperatures, or limiting the number of pages that can be formed continuously at multiple detection temperatures that are different from each other. Or you can run it. In addition, a plurality of temperature thresholds are set based on the detection results of the plurality of temperature detecting means. As a result, depending on whether or not the temperature distribution in the image forming apparatus is the target temperature distribution, a criterion for determining whether to execute the restriction on the number of pages that can be continuously imaged and the release of the restriction is set. It can be set more appropriately.
(Aspect D)
In the above-described aspect B or aspect C, a control unit such as the control unit 900 calculates a difference ΔT of detection results of the plurality of temperature detection units, and sets the temperature threshold based on the difference ΔT.
According to this, as described in the above-described embodiment, the difference ΔT between the detection results of the plurality of temperature detection units is likely to change due to the influence of the temperature distribution in the image forming apparatus. In this way, by setting the temperature threshold based on the difference ΔT of the detection results of the plurality of temperature detection means that change according to the temperature distribution in the image forming apparatus, according to the temperature distribution in the image forming apparatus. The temperature threshold can be set more appropriately and accurately.
(Aspect E)
In the aspect D, when the difference ΔT is smaller than a predetermined value, the control unit such as the control unit 900 reduces the temperature threshold used to determine whether to start limiting the number of pages on which continuous image formation is possible. Set as follows.
According to this, as described in the above embodiment, when the difference ΔT is smaller than a predetermined value, the heating by the heat source in the image forming apparatus spreads over the entire area and the temperature distribution in the image forming apparatus becomes uniform. An excessive temperature rise of the developer on the developer carrying member tends to occur. Accordingly, when the difference ΔT becomes smaller than a predetermined value, the temperature threshold value is decreased, and the restriction on the number of pages on which continuous image formation is possible is quickly started, whereby the developer on the developer carrier is excessively increased. The temperature can be prevented more reliably.
(Aspect F)
In any one of the above aspects A to E, the control unit such as the control unit 900 continues when the temperature T detected by the temperature detection unit such as the temperature sensor 905 is equal to or higher than a preset first temperature threshold T1. The number of pages on which image formation is possible is limited to a predetermined page number L or less, and then the restriction on the number of pages on which continuous image formation is possible is canceled when the detected temperature T becomes lower than a preset second temperature threshold value T2. To control.
According to this, as described in the above embodiment, based on the comparison result between the detected temperature T and the temperature thresholds T1 and T2, the limitation on the number of pages on which continuous image formation is possible and the cancellation of the limitation are controlled. Thereby, control becomes simpler compared with the case where the calculation result which estimates temperature is used.
(Aspect G)
In any one of the above aspects A to F, the control unit such as the control unit 900 is configured such that the temperature T detected by the temperature detection unit such as the temperature sensor 905 is equal to or higher than a preset first temperature threshold T1. Then, a transition is made to a restricted image forming operation mode in which the number of pages on which continuous image formation is possible is limited to a predetermined page number L or less, and in the restricted image forming operation mode, the detected temperature T is less than a preset second temperature threshold value T2. In such a case, control is performed so as to cancel the restriction on the number of pages on which continuous image formation is possible and shift to a normal image forming operation mode.
According to this, as described in the embodiment, the predetermined restricted image forming operation mode and the normal image forming operation mode are set in advance. The simple control of shifting the image forming operation mode makes it possible to limit the number of pages on which continuous image formation is possible and to cancel the limitation.
(Aspect H)
In the above aspect F or aspect G, the apparatus further includes a temperature threshold storage unit such as a storage unit 901 that stores set values of the first temperature threshold T1 and the second temperature threshold T2, and the control unit such as the control unit 900 includes: Based on the setting value of the temperature threshold value stored in the temperature threshold value storage means, control is performed so as to limit the number of pages that can be formed continuously and to cancel the limitation.
According to this, as described in the above embodiment, the temperature thresholds T1 and T2 are set to arbitrary values according to the actual usage environment or usage, and the mode is changed to the intermittent printing operation mode and the normal printing operation mode. Transition can be controlled. Accordingly, it is possible to more reliably reduce the occurrence of problems such as toner melting due to a rise in the temperature of the developer carrying member such as the developing roller 12, and it is possible to minimize a decrease in productivity during image formation. In addition, since the temperature threshold values T1 and T2 are stored in the temperature threshold value storage means, the temperature threshold values T1 and T2 can be reused for the subsequent control, so that the efficiency of the control can be improved.
(Aspect I)
In aspect H, a control unit such as the control unit 900 switches the set value of the temperature threshold based on whether or not a peripheral device such as a finisher that can be mounted around the image forming apparatus is mounted.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detection means due to the presence or absence of the peripheral device.
(Aspect J)
In the above aspect H, the control unit such as the control unit 900 is configured to selectively execute an image forming operation for forming a full-color image and an image forming operation for forming a monochrome image. The setting value of the temperature threshold value is switched based on the ratio between the full color image and the monochrome image in the most recent image forming operation.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detecting unit due to the ratio of the full color image and the monochrome image in the most recent image forming operation.
(Aspect K)
In the aspect H, the control unit is configured to selectively execute a single-sided image forming operation for forming an image on one side of a recording medium such as the recording paper P and a double-sided image forming operation for forming an image on both sides of the recording medium. A control unit such as 900 switches the setting value of the temperature threshold based on the ratio of the recording medium for single-sided image formation or the ratio of the recording medium for double-sided image formation in the image forming operation of the most recent predetermined number of recording media.
According to this, as described in the above embodiment, the measurement error of the temperature detection means due to the ratio of the recording medium for single-sided image formation or the ratio of the recording medium for double-sided image formation in the image forming operation of the most recent predetermined number of recording media. The influence of can be reduced.
(Aspect L)
In the aspect H, a control unit such as the control unit 900 switches the setting value of the temperature threshold value based on the number of image forming pages or the number of recording media per one most recent image forming job.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detection means due to the number of image forming pages or the number of recording media per one most recent image forming job. .
(Aspect M)
In the aspect H, the image forming apparatus further includes a plurality of fans that generate airflow, and the control unit such as the control unit 900 is configured to control the temperature threshold value based on the number of operating fans among the plurality of fans. Switch the setting value.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detecting means due to the number of operating fans.
(Aspect N)
In the aspect H, the image forming apparatus further includes a fan that generates an air flow, and a control unit such as the control unit 900 switches the set value of the temperature threshold value based on the rotation speed of the fan.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detecting means due to the rotational speed of the fan.
(Aspect O)
In the above aspect H, the control means such as the control unit 900 includes at least the surface movement speed (linear velocity) of the image carrier such as the photosensitive member 3 and the surface movement speed (linear velocity) of the developer carrier such as the developing roller 12. Based on one, the set value of the temperature threshold is switched.
According to this, as described in the above embodiment, it is possible to reduce the influence of the measurement error of the temperature detecting means due to at least one of the surface movement speed of the image carrier and the surface movement speed of the developer carrier.
(Aspect P)
In any one of the above aspects H to O, the controller 900 further includes a temperature threshold input unit such as an operation unit 902 for inputting a set value of at least one of the first temperature threshold T1 and the second temperature threshold T2. The control means such as the control controls the temperature threshold setting value stored in the temperature threshold storage means to be switched to the temperature threshold setting value input by the temperature threshold input means.
According to this, as described in the above embodiment, it is possible to control the transition to the intermittent printing operation mode and the normal printing operation mode by setting the temperature threshold values T1 and T2 to arbitrary values. Further, the user can set the temperature thresholds T1 and T2 according to the actual usage environment and usage in the actual usage location and market. Therefore, it is possible to further reduce the occurrence of problems such as toner melting due to a rise in the temperature of the developer carrying member such as the developing roller 12, and it is possible to minimize a decrease in productivity during image formation.
(Aspect Q)
In any one of the above aspects H to P, the magnitude relationship between the temperature threshold values T1 and T2 is T1> T2.
According to this, as described in the above embodiment, the developing unit 7 includes a developer carrying member such as the developing roller 12 that is continuously printed immediately after the restriction on the number of continuously printed pages is released and the temperature rapidly rises. It is possible to prevent the toner in the developing device from melting.

1 (1Y, 1C, 1M, 1K) Image forming unit 2 (2Y, 2C, 2M, 2K) Photoreceptor unit 3 (3Y, 3C, 3M, 3K) Photoreceptor 7 (7Y, 7C, 7M, 7K) Developing unit 12 (12Y, 12C, 12M, 12K) Developing roller 15 (15Y, 15C, 15M, 15K) Developing sleeve 20 Optical writing unit 900 Control unit 901 Storage unit 902 Operation unit 905 (905K, 905Y) Temperature sensor 906 Development drive motor

JP 2010-134407 A JP 2006-251504 A JP 2012-198495 A

Claims (17)

A latent image forming unit that forms a latent image on the image carrier and a developing device that develops the latent image on the image carrier with a developer carried on the developer carrier, and continuously performing image forming operations on a plurality of pages. An image forming apparatus that can be executed
Temperature detecting means for detecting the temperature inside or around the developing device that changes corresponding to the temperature of the developer carrying member is provided at a plurality of locations of the image forming apparatus,
An image forming apparatus comprising: a control unit configured to control a limit on the number of pages on which continuous image formation is possible and release of the limit based on detection results of the temperature detection units at the plurality of locations. The image forming apparatus according to claim 1.
The control means includes
Based on at least one detection result of the temperature detection means in the plurality of locations and a preset temperature threshold, control the limit on the number of pages that can be continuously formed,
The image forming apparatus, wherein the temperature threshold value is set based on detection results of the temperature detecting means at the plurality of locations. The image forming apparatus according to claim 1 or 2,
The control means includes
Based on at least one detection result of the temperature detection means of the plurality of locations and a plurality of preset temperature thresholds, control the limitation on the number of pages that can be formed continuously and the cancellation of the limitation,
An image forming apparatus, wherein at least one of the plurality of temperature thresholds is set based on detection results of the plurality of temperature detecting means. The image forming apparatus according to claim 2 or 3,
The image forming apparatus, wherein the control unit calculates a difference ΔT of detection results of the temperature detection units at the plurality of locations, and sets the temperature threshold based on the difference ΔT. The image forming apparatus according to claim 4.
The control means sets the temperature threshold used to determine whether or not to start limiting the number of pages on which continuous image formation is possible when the difference ΔT is smaller than a predetermined value. Image forming apparatus. The image forming apparatus according to any one of claims 2 to 5,
The control means includes
When the temperature T detected by the temperature detection means is equal to or higher than a preset first temperature threshold value T1, the number of pages on which continuous image formation is possible is limited to a predetermined number L or less, and then the temperature T is detected in advance. An image forming apparatus that performs control so as to release the restriction on the number of pages on which continuous image formation is possible when the temperature becomes lower than a set second temperature threshold value T2. The image forming apparatus according to any one of claims 2 to 6,
The control means includes
When the temperature T detected by the temperature detection means is equal to or higher than a preset first temperature threshold value T1, the mode shifts to a restricted image forming operation mode in which the number of pages on which continuous image formation is possible is limited to a predetermined number L or less. ,
When the detected temperature T is lower than a preset second temperature threshold T2 in the restricted image forming operation mode, the restriction on the number of pages on which continuous image formation is possible is canceled and the normal image forming operation mode is set. An image forming apparatus controlled to shift. The image forming apparatus according to claim 6 or 7,
Temperature threshold storage means for storing set values of the first temperature threshold T1 and the second temperature threshold T2;
The control unit performs control so as to limit the number of pages on which the continuous image can be formed and to cancel the limitation based on a temperature threshold setting value stored in the temperature threshold storage unit. Image forming apparatus. The image forming apparatus according to claim 8.
The image forming apparatus characterized in that the control means switches the set value of the temperature threshold based on whether or not a peripheral device that can be mounted around the image forming apparatus is attached. The image forming apparatus according to claim 8.
The control means includes
An image forming operation for forming a full-color image and an image forming operation for forming a monochrome image can be selectively executed.
An image forming apparatus, wherein the set value of the temperature threshold value is switched based on a ratio between a full-color image and a monochrome image in the most recent image forming operation. The image forming apparatus according to claim 8.
The control means includes
A single-sided image forming operation for forming an image on one side of the recording medium and a double-sided image forming operation for forming an image on both sides of the recording medium are selectively executable,
An image forming apparatus, wherein the setting value of the temperature threshold value is switched based on a ratio of a recording medium for single-sided image formation or a ratio of recording mediums for double-sided image formation in an image forming operation of the most recent predetermined number of recording media. The image forming apparatus according to claim 8.
The image forming apparatus according to claim 1, wherein the control unit switches the set value of the temperature threshold based on the number of image forming pages per one most recent image forming job or the number of recording media. The image forming apparatus according to claim 8.
A plurality of fans for generating airflow in the image forming apparatus;
The image forming apparatus, wherein the control unit switches a set value of the temperature threshold based on the number of operating fans among the plurality of fans. The image forming apparatus according to claim 8.
A fan for generating an airflow in the image forming apparatus;
The image forming apparatus according to claim 1, wherein the control unit switches the set value of the temperature threshold based on the number of rotations of the fan. The image forming apparatus according to claim 8.
The image forming apparatus according to claim 1, wherein the controller switches the set value of the temperature threshold based on at least one of a surface movement speed of the image carrier and a surface movement speed of the developer carrier. The image forming apparatus according to any one of claims 6 to 15,
A temperature threshold value input means for inputting a set value of at least one of the first temperature threshold value T1 and the second temperature threshold value T2,
The image forming apparatus, wherein the control unit switches a temperature threshold setting value stored in the temperature threshold storage unit to a temperature threshold setting value input by the temperature threshold input unit. The image forming apparatus according to any one of claims 6 to 16,
An image forming apparatus, wherein a magnitude relationship between the first temperature threshold value T1 and the second temperature threshold value T2 is T1> T2.