JP2014178526A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of more appropriately determining replacement timing of a development cartridge.SOLUTION: A replacement timing threshold determination section 2C sets a threshold using a cumulative rotation number of a development roller as a parameter. A cumulative rotation number count section 2A counts the cumulative rotation number NR of the development roller. A replacement timing determination section 2D determines replacement timing of a development cartridge by comparing the cumulative rotation number NR with the threshold. At that time, the replacement timing threshold determination section 2C sets the threshold to a value that the replacement timing of the development cartridge becomes earlier as a temperature and humidity are higher according to a temperature T detected by a temperature sensor 6 and relative humidity H detected by a humidity sensor 5, so the replacement timing of the development cartridge is more appropriately determined according to the temperature and the humidity in a body casing.

Description

  The present invention relates to an image forming apparatus including a developing cartridge that is replaceably mounted on a casing.

  2. Description of the Related Art Conventionally, in an image forming apparatus in which a developing cartridge that contains a developer can be replaced, an image forming apparatus that is configured to determine when to replace a mounted developing cartridge is known. For example, an image forming apparatus described in Patent Document 1 includes a light emitting element that enters light into a container that stores toner, and a light receiving element that receives light transmitted through the container, and receives light output from the light receiving element. By detecting the amount of toner in the container based on the signal, it is determined whether or not the toner cartridge is in a replacement period.

JP 2000-10394 A

  As described above, it has been difficult to accurately determine the toner amount when the toner cartridge replacement timing is determined using the light emitting element and the light receiving element.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can more appropriately determine when to replace a developing cartridge.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a developer cartridge having a developer container and a developer carrier, a casing in which the developer cartridge is replaceably mounted, a temperature in the casing, A sensor for detecting humidity and / or a control device are provided. The control device includes a usage amount estimation unit that estimates a cumulative usage amount of the developing cartridge, a replacement timing determination unit that determines a replacement timing of the developing cartridge based on a threshold value using the cumulative usage amount of the developing cartridge as a parameter, and a sensor that detects Threshold value determining means for determining a threshold value corresponding to the measured temperature and / or humidity. Then, the threshold value determining means determines the threshold value to a value at which the replacement timing of the developing cartridge is earlier as the temperature and / or humidity is higher.

  In this image forming apparatus, the threshold value determining unit determines a threshold value using the accumulated usage amount of the developing cartridge as a parameter as a threshold value for determining the replacement timing of the developing cartridge. On the other hand, the usage amount estimation means estimates the cumulative usage amount of the developing cartridge. Then, by comparing the accumulated usage amount of the developing cartridge estimated by the usage amount estimating unit with the threshold value determined by the threshold value determining unit, the replacement timing determining unit determines the replacement timing of the developing cartridge.

  At this time, the threshold value determining unit determines the threshold value to a value that, as the temperature and / or humidity is higher, the developing cartridge replacement timing is earlier corresponding to the temperature and / or humidity in the casing detected by the sensor. Therefore, in this image forming apparatus, the replacement timing of the developing cartridge is determined earlier as the temperature and / or humidity in the housing is higher and the fog phenomenon due to the deterioration of the charging characteristics of the developer is more likely to occur. The lower the temperature and / or humidity and the less likely the fogging phenomenon is, the later the developer cartridge replacement time is determined, and the developer cartridge replacement time is determined more appropriately according to the temperature and / or humidity inside the housing. Is done.

  In this image forming apparatus, the threshold value determining unit determines the threshold value from threshold data that changes stepwise according to changes in temperature and / or humidity in the housing as a threshold value for determining the replacement timing of the developing cartridge. Alternatively, the threshold may be determined from continuously changing threshold data.

  Here, the sensor outputs the temperature and / or humidity detected when receiving the print job to be printed on the recording sheet to the threshold value determining unit, and the threshold value determining unit outputs the print job according to the acquired temperature and / or humidity. The threshold value can be determined before the printing operation by. In this case, it is preferable because the replacement timing of the developing cartridge is appropriately determined for each print job.

  Further, the usage amount estimating means for estimating the cumulative usage amount of the developing cartridge can be a rotation number counting means for counting the cumulative number of rotations of the developer carrier.

  Furthermore, the sensor can be integrally configured as a temperature / humidity sensor that simultaneously detects temperature and humidity.

  According to the image forming apparatus of the present invention, the replacement timing of the developing cartridge can be more appropriately determined according to the temperature and / or humidity in the housing.

1 is a side sectional view showing a schematic structure of a laser printer as an image forming apparatus according to an embodiment of the present invention. It is a block block diagram of the control apparatus with which the laser printer shown in FIG. 1 is provided. It is an area map of absolute humidity which shows temperature and relative humidity as parameters. 5 is a graph showing a threshold value for developing cartridge replacement timing according to absolute humidity, with the cumulative number of rotations of the developing roller as a parameter. It is a flowchart which shows the process sequence of the control apparatus shown in FIG. It is a threshold value graph which shows the modification of the graph shown in FIG. 6 is a graph showing a threshold value of a developing cartridge replacement timing that changes according to temperature, with a cumulative number of rotations of the developing roller as a parameter. 6 is a graph showing a threshold value for developing cartridge replacement timing that changes according to relative humidity, with the cumulative number of rotations of the developing roller as a parameter.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of an image forming apparatus according to the invention will be described in detail with reference to the drawings as appropriate. An image forming apparatus according to an embodiment is embodied as a laser printer 1 as illustrated in FIG. 1, for example. In the following description, the side facing the user who uses the laser printer 1, that is, the right side of the paper surface of FIG. 1 is “front”, the left side is “rear”, the vertical direction is “up / down”, and the front side is “ The “left” and the back side are “right”.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a feeder unit 10 for feeding a sheet S as an example of a recording sheet, an image forming unit 20 for forming an image on the sheet S, and the like. It is provided in the main body casing 30. Here, the image forming unit 20 includes a scanner unit 40 that is an exposure unit, a process cartridge 50 that constitutes a developing unit and a transfer unit, a fixing unit 60, and the like.

<Configuration of feeder section>
The feeder unit 10 includes a paper feed tray 11 that is detachably attached to the bottom of the main body casing 30, and a paper pressing plate 12 that is disposed at the front of the paper feed tray 11. The feeder unit 10 includes a paper feed roller 13 and a paper feed pad 14 disposed above the front end portion of the paper feed tray 11, and a paper disposed downstream of the paper feed roller 13 in the transport direction of the paper S. Powder removing rollers 15 and 16 are provided. Further, the feeder unit 10 includes a registration roller 17 disposed on the downstream side in the transport direction of the paper S with respect to the paper dust removing rollers 15 and 16.

  In the feeder unit 10, the paper S accommodated in the paper feed tray 11 is moved toward the paper feed roller 13 by the paper pressing plate 12. The sheet S sandwiched between the sheet feeding roller 13 and the sheet feeding pad 14 is transferred to the image forming unit 20 via the paper dust removing rollers 15 and 16 and the registration roller 17 by the rotation of the sheet feeding roller 13. Be transported.

<Configuration of scanner unit>
The scanner unit 40 is disposed in the upper part of the main body casing 30 and includes a laser light emitting unit (not shown), a polygon mirror 41, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In the scanner unit 40, the laser beam is irradiated on the surface (circumferential surface) of the photosensitive drum 51 in the process cartridge 50 by high-speed scanning through a path indicated by a one-dot chain line.

<Process cartridge configuration>
The process cartridge 50 is disposed below the scanner unit 40 and is detachably attached to the main casing 30 by being attached to and detached from the main casing 30 by moving in the front-rear direction. The process cartridge 50 includes a drum unit including a photosensitive drum 51, a scorotron charger 52, and a transfer roller 53, and a developing cartridge configured to be detachable from the drum unit.

  The developing cartridge includes a developing roller 54 as a developer carrying member, a layer thickness regulating blade 55, a supply roller 56, and a toner hopper 57 (developer containing portion) as a developer containing portion.

  In the process cartridge 50 including such a developing cartridge, the surface of the photosensitive drum 51 charged by the scorotron charger 52 is exposed to a laser beam from the scanner unit 40, thereby electrostatically forming the surface of the photosensitive drum 51. A latent image is formed. Then, a toner image (developer image) is formed on the surface of the photosensitive drum 51 by supplying toner, which is a developer in the toner hopper 57, to the electrostatic latent image via the supply roller 56 and the development roller 54. Is done. Thereafter, when the sheet S is conveyed between the photosensitive drum 51 and the transfer roller 53, a transfer bias is applied to the transfer roller 53, so that the toner image carried on the surface of the photosensitive drum 51 is transferred to the transfer roller 53. Is transferred onto the surface of the paper S, and thus an image is formed on the surface of the paper S.

<Configuration of fixing unit>
The fixing unit 60 includes a heating roller 61 for thermally fixing the toner image transferred onto the paper S, and a pressure roller 62 that presses the paper S with the heating roller 61 interposed therebetween. The fixing unit 60 is disposed on the downstream side in the conveyance direction of the paper S conveyed from the process cartridge 50. The sheet S thermally fixed by the fixing unit 60 is discharged onto a sheet discharge tray 72 outside the main body casing 30 by a pair of discharge rollers 71 that rotate in the conveyance direction of the sheet S.

  Here, at the time of double-sided printing in which images are formed on both sides of the paper S, the paper discharge roller 71 rotates reversely before the entire paper S is discharged onto the paper discharge tray 72, so that the paper S is moved to the main casing. Pull back into 30. The sheet S pulled back into the main body casing 30 passes through the rear side of the fixing unit 60 by switching of the flapper 73 and is then sent to the duplex conveyance path unit 80.

<Configuration of duplex transport path unit>
The duplex conveyance path unit 80 is a reconveying mechanism for duplex conveyance, and is disposed between the image forming unit 20 and the paper feed tray 11. Here, “double-sided conveyance” means that the paper S is reversed and returned between the photosensitive drum 51 and the transfer roller 53 of the process cartridge 50 in order to print the back surface of the paper S on which the front surface is printed. Refers to the conveyance to be performed.

  The double-sided conveyance path unit 80 has a guide member 81 that switches the direction of the sheet S conveyed downward through the rear side of the fixing unit 60 forward, and the sheet S guided by the guide member 81 on the front side of the photosensitive drum 51. And a plurality of pairs of return rollers 82 arranged in parallel in the front-rear direction. Then, the sheet S discharged from the double-sided conveyance path unit 80 is guided toward the registration roller 17 by the guide 83 in front of the double-sided conveyance path unit 80 with the front and back being reversed. Thus, after the leading edge of the sheet S is aligned by the registration roller 17, the sheet S is conveyed again between the photosensitive drum 51 and the transfer roller 53, and the toner image on the surface of the photosensitive drum 51 is transferred to the back surface of the sheet S. .

  Here, the toner, which is the developer accommodated in the toner hopper 57 of the developing cartridge constituting the process cartridge 50, generally deteriorates as the cumulative usage amount of the developing cartridge increases, and the charging performance decreases. When the toner having a lowered charging performance is used as it is, a so-called fog phenomenon occurs in which the toner adheres to a portion other than the image of the developer formed on the paper S. Therefore, in order to prevent such a fog phenomenon, the laser printer 1 as an image forming apparatus according to an embodiment estimates the deterioration state of the toner stored in the toner hopper 57 and notifies the replacement timing of the developing cartridge. A control device.

<Configuration of control device>
As shown in FIG. 2, the control device 2 includes a cumulative rotation number counting unit 2A, a gate unit 2B, a replacement timing threshold value determination unit 2C, a replacement timing determination unit 2D, and a print job execution unit 2E, which are microcomputers. It is configured using hardware and software. The microcomputer constituting the control device 2 includes an input / output interface I / O, an A / D converter, a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that temporarily stores input data and the like. And a CPU (Central Processing Unit) for executing the program.

  The cumulative rotation number counting unit 2A functions as a usage amount estimation unit that estimates the cumulative usage amount of the developer cartridge. The cumulative rotation number counting unit 2A functions as a rotation number counting unit that counts the cumulative rotation number of the developer carrier. Count the number of rotations. The accumulated rotation number counting unit 2A obtains the rotation number of the developing roller 54 from the rotation number sensor 4, thereby accumulating and counting the accumulated rotation number NR of the developing roller 54 from when the developing cartridge is replaced. Then, the cumulative rotation number counting unit 2A outputs information on the counted cumulative rotation number NR to the replacement time determination unit 2D.

  The gate unit 2 </ b> B constantly acquires the relative humidity detection signal H detected by the humidity sensor 5 and the temperature detection signal T detected by the temperature sensor 6. When the gate unit 2B obtains a print job signal PJ for printing on the paper S from a personal computer (PC) 3 using the laser printer 1 as an output device, the relative humidity detection signal H and temperature detection at that time are obtained. The signal T is output to the replacement time threshold value determination unit 2C.

By referring to the graph shown in FIG. 3 based on the relative humidity detection signal H and the temperature detection signal T acquired from the replacement timing threshold value determination unit 2C and the gate unit 2B, the absolute humidity (g / m ³ ) is, for example, A low temperature and low humidity region LL that includes a point of less than 3 and a temperature of 10 ° C. and a humidity of 20%, and a normal temperature and normal humidity region that includes an absolute humidity of about 3 to 10 and a temperature of 23 ° C. and a humidity of 50% JJ is distinguished from a high-temperature and high-humidity region HH having a point where the absolute humidity is 10 or more, the temperature is 32 ° C., and the humidity is 80%.

  Then, the replacement timing threshold value determination unit 2C refers to threshold data that changes stepwise corresponding to the determined low-temperature and low-humidity region LL, normal-temperature and normal-humidity region JJ, and high-temperature and high-humidity region HH. Th is determined. That is, as shown in the graph of FIG. 4, the replacement timing threshold value determination unit 2C refers to threshold value data that changes stepwise with the cumulative number of rotations NR of the developing roller 54 as a parameter, so that the replacement temperature threshold value determination unit 2C A threshold value in which the value of the JJ environment at normal humidity is small and the value of the HH environment at high temperature and high humidity is lower than the JJ environment at normal temperature and humidity is determined as the threshold Th for the development cartridge replacement time.

  Here, the threshold value Th using the cumulative number of rotations NR of the developing roller 54 as a parameter is determined to be, for example, 100,000 rotations in the low temperature and low humidity LL environment, and is determined to be, for example, 75,000 rotations in the JJ environment at room temperature and humidity. In a high-temperature and high-humidity HH environment, for example, it is determined to be 50,000 revolutions. Accordingly, the replacement timing of the developing cartridge is delayed in the low-temperature, low-humidity LL environment and earlier in the high-temperature, high-humidity HH environment than the JJ environment at normal temperature and humidity.

  The replacement time determination unit 2D compares the cumulative rotation number NR acquired from the cumulative rotation number counting unit 2A with the threshold value Th acquired from the replacement time threshold value determination unit 2C, thereby determining whether or not the development cartridge has reached the replacement time. judge.

  If the development cartridge has not yet reached the replacement time, the replacement time determination unit 2D outputs a print job signal PJ to the print job execution unit 2E. As a result, a print job in response to a request from the personal computer (PC) 3 is executed. On the other hand, when the development cartridge has reached the replacement time, the replacement time determination unit 2D outputs a signal for notifying the replacement time of the development cartridge to the replacement time notification device 7.

  Although not shown, the replacement time notification device 7 is configured by an appropriate blinking lamp disposed at an easily viewable position of the main body casing 30, for example, at the top of the front portion. Further, the rotation number sensor 4, the humidity sensor 5, and the temperature sensor 6 are arranged in the vicinity of the developing roller 54.

  In the laser printer 1 which is the image forming apparatus of the present embodiment configured as described above, in order to prevent the occurrence of a so-called fog phenomenon that toner adheres to a portion other than the image formed on the paper S. Then, the control device 2 estimates the deterioration state of the toner stored in the toner hopper 57 and notifies the replacement timing of the developing cartridge. Hereafter, the procedure of the process which the control apparatus 2 performs is demonstrated sequentially along the flowchart of FIG.

  First, in step S1, it is determined whether or not the control device 2 has acquired the print job signal PJ. This determination is repeated until the print job signal PJ is input to the gate unit 2B.

  When the print job signal PJ is input to the gate unit 2B, the gate unit 2B replaces the relative humidity detection signal H detected by the humidity sensor 5 and the temperature detection signal T detected by the temperature sensor 6 with the replacement timing threshold determination unit. Output to 2C. Accordingly, the replacement time threshold value determination unit 2C acquires the temperature T as step S2, and acquires the relative humidity H as step S3.

  In the next step S4, the replacement time threshold determination unit 2C determines the threshold for the replacement time of the developing cartridge. At that time, the replacement timing threshold value determination unit 2C performs the low temperature and low humidity region LL, the normal temperature and normal humidity region JJ, and the high temperature and high humidity region HH shown in FIG. 3 as the absolute humidity regions according to the temperature T and the relative humidity H. Is discriminated.

  Then, by referring to the threshold data shown in the graph of FIG. 4, the replacement time threshold value determination unit 2C has a low temperature and normal humidity JJ environment threshold value that is lower than the low temperature and low humidity LL environment, and a higher temperature than the normal temperature and normal humidity JJ environment. A threshold value at which the threshold value of the wet HH environment is reduced is determined as the threshold value Th for the development cartridge replacement time.

  In step S <b> 5, the accumulated rotation number counting unit 2 </ b> B obtains the accumulated rotation number NR of the developing roller 54 by obtaining the rotation number of the developing roller 54 from the rotation number sensor 4.

  In step S6, the cumulative number of rotations NR acquired from the cumulative number of rotations counting unit 2A is compared with the threshold value Th acquired from the replacement time threshold value determining unit 2C to exchange whether or not the development cartridge has reached the replacement time. The timing determination unit 2D determines.

  If the determination result by the replacement time determination unit 2D is NO and the development cartridge has not yet reached the replacement time, the replacement time determination unit 2D outputs the print job signal PJ to the print job execution unit 2E. In step S7, the print job execution unit 2E executes a print job in response to a request from the personal computer (PC) 3.

  On the other hand, when the determination result by the replacement time determination unit 2D is YES and the development cartridge has reached the replacement time, a signal for the replacement time determination unit 2D to notify the replacement time of the development cartridge is notified. By outputting to the apparatus 7, in step S8, the blinking lamp which is the replacement time notification device 7 blinks to notify the developer cartridge replacement time.

  Here, as shown in the graph of FIG. 4, the threshold value Th for determining the replacement timing of the developing cartridge is determined to be, for example, 100,000 rotations in the low temperature and low humidity LL environment, and in the JJ environment of normal temperature and humidity, for example, For example, it is determined to be 50,000 revolutions in a high-temperature and high-humidity HH environment. Therefore, the development cartridge is replaced most quickly in a high-temperature, high-humidity HH environment, in a room-temperature, normal-humidity JJ environment, slower than a high-temperature, high-humidity HH environment, and in the low-temperature, low-humidity LL environment.

  That is, in the laser printer 1 that is the image forming apparatus of the present embodiment, the temperature and humidity environment in the main body casing 30 is a high-temperature and high-humidity HH environment, the absolute humidity is high, and the fog phenomenon due to the deterioration of the charging characteristics of the developer. If it is likely to occur, the replacement timing of the developing cartridge is judged early, and conversely, the temperature and humidity environment in the main body casing 30 is a low temperature and low humidity LL environment, the absolute humidity is low, and the developer fogging phenomenon occurs. If it is difficult, it is determined that the developing cartridge replacement time is late. Therefore, according to the laser printer 1 of the present embodiment, it is possible to more appropriately determine the replacement timing of the developing cartridge according to the absolute humidity in the main body casing 30.

  The laser printer 1 as one embodiment of the image forming apparatus according to the present invention has been described above. However, the image forming apparatus according to the present invention is not limited to the laser printer 1 according to one embodiment, and has a specific configuration. Can be appropriately changed without departing from the spirit of the present invention.

  For example, the temperature sensor 6 and the humidity sensor 5 illustrated in FIG. 2 can be integrally configured as a temperature / humidity sensor. Further, the replacement time notification device 7 may be a liquid crystal display that displays the replacement time of the developing cartridge with characters or pictograms, or may be a speaker that notifies the replacement time of the developing cartridge by voice.

  2A acquires a print job signal PJ from the personal computer (PC) 3, and prints information from information such as the size of the paper S and the number of prints included in the print job signal PJ. The cumulative number of rotations of the developing roller 54 from when the developing cartridge is replaced may be estimated by integrating the number of rotations of the developing roller 54 for each job. In this case, the rotation number sensor 4 shown in FIG. 2 can be omitted.

  Here, the threshold value data referred to by the replacement timing threshold value determination unit 2C of the control device 2 shown in FIG. 2 to determine the threshold value Th is not limited to one that changes stepwise as shown in the graph of FIG. As shown in the graph of FIG. 6, it may be changed continuously.

  Further, either one of the humidity sensor 5 and the temperature sensor 6 shown in FIG. 2 may be omitted. When the humidity sensor 5 is omitted, the replacement timing threshold value determination unit 2C uses the threshold value data shown in the graph of FIG. 7, that is, the cumulative number of rotations NR and the temperature (° C.) of the developing roller 54 as parameters to respond to the temperature increase. The threshold Th of the replacement timing of the developing cartridge is determined with reference to threshold data of the characteristic that the cumulative rotation number NR decreases.

  On the other hand, when the temperature sensor 6 is omitted, the replacement timing threshold value determination unit 2C uses the threshold data shown in the graph of FIG. 8, that is, the relative rotation (NR) and the relative humidity (%) as parameters for the relative humidity. The threshold Th of the replacement timing of the developing cartridge is determined with reference to the threshold data of the characteristic that the cumulative number of rotations NR decreases in accordance with the increase of the developing cartridge.

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Control apparatus 2A Cumulative rotation frequency count part 2B Gate part 2C Replacement time threshold value determination part 2D Replacement time determination part 2E Print job execution part 3 Personal computer (PC)
4 Rotation Count Sensor 5 Humidity Sensor 6 Temperature Sensor 7 Replacement Time Notification Device 30 Main Body Casing 50 Process Cartridge 51 Photosensitive Drum 54 Developing Roller (Developer Carrier)
57 Toner hopper (developer container)
NR Cumulative number of rotations H Relative humidity T Temperature S Paper

Claims (6)

A developer cartridge having a developer container and a developer carrier;
A housing in which the developing cartridge is replaceably mounted;
A sensor for detecting temperature and / or humidity in the housing;
A control device,
The controller is
Usage estimation means for estimating the cumulative usage of the developing cartridge;
A replacement timing determination means for determining a replacement timing of the developing cartridge based on a threshold value using a cumulative usage amount of the developing cartridge as a parameter;
Threshold value determining means for determining the threshold value corresponding to the temperature and / or humidity detected by the sensor;
The image forming apparatus according to claim 1, wherein the threshold value determining unit determines the threshold value to a value such that the higher the temperature and / or humidity is, the earlier the replacement timing of the developing cartridge is.   The image forming apparatus according to claim 1, wherein the threshold value determining unit changes the threshold value in a stepwise manner in accordance with changes in the temperature and / or humidity.   The image forming apparatus according to claim 1, wherein the threshold value determining unit continuously changes the threshold value according to a change in the temperature and / or humidity. The sensor outputs the temperature and / or humidity detected when receiving a print job to be printed on the recording sheet to the threshold value determining means,
The image forming apparatus according to claim 1, wherein the threshold value determining unit sets the threshold value before a printing operation by the print job according to the acquired temperature and / or humidity.   The image forming apparatus according to claim 1, wherein the usage amount estimation unit is a rotation number counting unit that counts the cumulative number of rotations of the developer carrying member.   The image forming apparatus according to claim 1, wherein the sensor is a temperature / humidity sensor that simultaneously detects the temperature and humidity.

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