JP2013011693A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus that reduces color mixing is provided.
An image forming apparatus according to the present invention includes a magenta developing cartridge 56M that stores magenta toner, a magenta developing roller, a magenta photosensitive drum 51M, and a cyan developing cartridge 56C that stores cyan toner. The cyan developing roller, the cyan photosensitive drum 51C disposed on the downstream side in the transport direction of the sheet S with respect to the magenta photosensitive drum 51M, the cumulative number of rotations of the magenta developing roller, and the cyan developing roller. If the storage means for storing the cumulative rotation speed and the magenta development roller exceed the first threshold value, it is determined that the magenta development cartridge 56M is in the replacement period, and the cumulative rotation speed of the cyan development roller is Determining means for determining that the cyan developing cartridge 56C is in a replacement period when the second threshold value is exceeded, 2 thresholds, during at least an initial use, and is set to a value smaller than the first threshold value.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus capable of performing color printing.

  As an image forming apparatus such as a color printer, a tandem type is known in which photosensitive drums corresponding to yellow, magenta, cyan, and black are arranged side by side along a moving direction of a transfer medium. In general, a tandem type image forming apparatus is configured so that a developing cartridge, which is provided corresponding to each photosensitive drum and contains toner of each color, can be replaced with the main body of the image forming apparatus. .

  Conventionally, an image forming apparatus that detects the remaining amount of toner in a developing cartridge and determines the replacement timing of the developing cartridge from the remaining amount of toner is known (for example, see Patent Document 1). Specifically, in this image forming apparatus, a toner end sensor for detecting the remaining amount of toner in each developing cartridge and a cartridge life determination unit are provided. The cartridge life determination unit determines that it is time to replace the developing cartridge when the remaining amount of toner detected by the toner end sensor is equal to or less than a predetermined value.

JP 2009-282076 A

  By the way, in the tandem type image forming apparatus, the toner transferred from the photosensitive drum to the transfer medium may be transferred (reversely transferred) to the photosensitive drum disposed downstream in the moving direction of the transfer medium. is there. The reversely transferred toner is usually collected by the developing roller and dispersed in the toner accommodated in the developing cartridge as the photosensitive drum rotates.

  However, in the technique described in Patent Document 1 described above, due to a difference in toner consumption and the like, the developing cartridge corresponding to the photosensitive drum arranged on the upstream side is photosensitive on the downstream side. There is a case where the cartridge is replaced with a new one earlier than the developing cartridge corresponding to the body drum. In this case, the new toner is collected on the developing roller carrying the old toner by reverse transfer. However, since the new toner has a higher charging ability than the old toner, it is difficult to be dispersed in the developing cartridge, It will remain. As a result, the toner remaining on the developing roller again moves to the photosensitive drum and is transferred to the transfer medium, causing color mixing.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that reduces color mixing.

In order to achieve the above-described object, an image forming apparatus of the present invention includes an apparatus main body, a first cartridge that contains a developer of a first color other than black, and is configured to be replaceable with respect to the apparatus main body. A first developer carrying member carrying the first color developer, a first photosensitive member supplied with the developer from the first developer carrying member, and a second color developer other than black are accommodated. A second cartridge configured to be replaceable with respect to the apparatus main body, a second developer carrying member carrying the developer of the second color, and a downstream side in the moving direction of the transfer medium with respect to the first photosensitive member. A second photosensitive member disposed and supplied with a developer from the second developer carrying member; a storage unit; and a determination unit.
The storage means includes a first value that increases with the rotation of the first developer carrier after the first cartridge is attached to the apparatus main body, and a second developer carrier after the second cartridge is attached to the apparatus main body. A second value that increases as the body rotates is stored.
The determination means determines that the first cartridge is in the replacement time when the first value exceeds the first threshold, and the second value when the second value exceeds the second threshold. It is determined that the cartridge is ready for replacement.
The second threshold is set to a value smaller than the first threshold at least during initial use.

  According to the image forming apparatus configured as described above, the second color developer that is supplied to the second photoconductor disposed downstream of the first photoconductor in the moving direction of the transfer medium is accommodated. The cartridge can be replaced earlier than the first cartridge. As a result, it is possible to reduce color mixing that occurs when the first color developer is newer than the second color developer.

  It is desirable that the second threshold value is always set to a value smaller than the first threshold value.

  According to the image forming apparatus configured as described above, the second cartridge can be reliably replaced first.

  The second threshold value may be set to a value equal to the first threshold value after the first replacement of the second cartridge.

  According to the image forming apparatus configured as described above, the replacement frequency of the second cartridge can be reduced as compared with the case where the second threshold value is always smaller than the first threshold value.

  In the image forming apparatus in which the second threshold value is set equal to the first threshold value after the first replacement of the second cartridge, the storage unit determines whether the second cartridge has been replaced. The data is stored, and when the determination unit determines that it is time to replace the first cartridge for the first time, it can determine that it is time to replace the second cartridge if the replacement of the second cartridge has not been performed so far. desirable.

  According to the image forming apparatus configured as described above, it is possible to prevent the first cartridge from being replaced first for some reason.

  In the above-described image forming apparatus, when the determination unit determines that the first cartridge is at the replacement time, the difference between the second threshold value and the second value stored in the storage unit is within a predetermined value. In some cases, it is desirable to determine that it is time to replace the second cartridge.

  According to the image forming apparatus configured as described above, it is possible to avoid replacing the first cartridge with a new one when the second color developer in the second cartridge is excessively deteriorated. .

  In the above-described image forming apparatus, it is desirable that the charging ability of the second color developer is less likely to be lower than the charging ability of the first color developer.

  According to the image forming apparatus configured as described above, the charge amount of the second color developer can be prevented from being excessively smaller than that of the first color developer.

  In the above-described image forming apparatus, the first value is the cumulative rotational speed of the first developer carrier, and the second value is the cumulative rotational speed of the second developer carrier.

  According to the present invention, since the second cartridge disposed downstream of the first cartridge in the moving direction of the transfer medium can be replaced earlier, color mixing that occurs when the second cartridge is older than the first cartridge. Can be reduced.

1 is a side sectional view showing a color printer according to a first embodiment of the present invention. It is a figure which shows the structure of a control part. FIG. 3 is a diagram for explaining the replacement timing of the magenta developer cartridge and the cyan developer cartridge according to the first embodiment of the present invention, and is a diagram at the time of initial use and a diagram at the time of multiple use (b). is there. 6 is a flowchart illustrating control for determining the replacement timing of the developing cartridge by the control unit of the image forming apparatus according to the first embodiment of the present disclosure. FIG. 10 is a diagram for explaining a replacement timing of a magenta developing cartridge and a cyan developing cartridge of an image forming apparatus according to a second embodiment. 10 is a flowchart illustrating control for determining a replacement timing of a developing cartridge by a control unit of an image forming apparatus according to a second embodiment of the present invention. FIG. 7A is a diagram for explaining the replacement timing of a yellow developing cartridge, a cyan developing cartridge, and a magenta developing cartridge of an image forming apparatus according to a modification, and FIG. It is a figure (b) explaining the modification of these.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of the color printer 1 (image forming apparatus) will be briefly described, and then the details of the features of the present invention will be described.

  Further, in the following explanation, explanation will be given in the direction based on the user when the color printer 1 is used. That is, in FIG. 1, the left side is “front side”, the right side is “rear side”, the back side in the vertical direction of the paper is “left side”, and the front side of the vertical direction of the paper is “right side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Overall structure of color printer>
As shown in FIG. 1, a color printer 1 includes a paper feeding unit 20 that feeds a sheet S as an example of a transfer medium in an apparatus main body 2 and an image forming unit that forms an image on the fed paper S. 30, a paper discharge unit 90 that discharges the paper S on which an image is formed, and a control unit 100.

  An opening 2 </ b> A is formed in the upper part of the apparatus main body 2. The opening 2A is opened and closed by an upper cover 3 that is rotatably supported by the apparatus main body 2. An upper surface of the upper cover 3 serves as a paper discharge tray 4 that accumulates the paper S discharged from the apparatus main body 2.

  The paper feeding unit 20 is provided at a lower portion in the apparatus main body 2, and a paper feeding tray 21 that is detachably attached to the apparatus main body 2, and a paper supply mechanism that conveys the paper S from the paper feeding tray 21 to the image forming unit 30. 22 is provided. The paper supply mechanism 22 is provided on the front side of the paper feed tray 21 and includes a paper feed roller 23, a separation roller 24, and a separation pad 25.

  In the paper feed unit 20 configured in this way, the paper S in the paper feed tray 21 is separated one by one and sent upward, and passes through between the paper dust removal roller 26 and the pinch roller 27 in the process. After the powder is removed, the direction is changed backward through a conveyance path (not shown) and supplied to the image forming unit 30.

  The image forming unit 30 includes four LED units 40, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

  The LED unit 40 is swingably connected to an LED mounting member (not shown) provided at the lower portion of the upper cover 3, and is appropriately positioned and supported by a positioning member (not shown) provided on the apparatus body 2. Yes.

  The process cartridge 50 is arranged in the front-rear direction between the upper cover 3 and the paper feeding unit 20, and includes a drum cartridge 58 and a developing cartridge 56 as an example of a cartridge configured to be detachable from the drum cartridge 58. It has.

  The drum cartridge 58 includes a photosensitive drum 51 as an example of a photosensitive member, a scorotron charger 52, and the like. The drum cartridge 58 may be detachable from the apparatus main body 2 or may be fixed to the apparatus main body 2.

  The photosensitive drum 51 is indicated by reference numerals 51K, 51Y, 51M, and 51C corresponding to the respective colors of black, yellow, magenta, and cyan, in this order from the upstream side in the transport direction of the paper S (transfer medium movement direction). Are arranged side by side. That is, the magenta photosensitive drum 51M is disposed downstream of the yellow photosensitive drum 51Y in the transport direction of the paper S, and the cyan photosensitive drum 51C is paper with respect to the magenta photosensitive drum 51M. It is arranged downstream in the transport direction of S.

  The developing cartridge 56 includes a developing roller 53 as an example of a developer carrier, a supply roller 54, a layer thickness regulating blade 57, and a toner storage chamber 55 for storing toner as an example of a developer.

  Further, in the normal state, the developer cartridge 56 is indicated by the reference numerals 56K, 56Y, 56M, and 56C that store toners for black, yellow, magenta, and cyan from the upstream side in the transport direction of the paper S. They are arranged in this order. As described above, the toner carried on the photosensitive drum 51 disposed on the downstream side in the transport direction of the paper S is more than the toner carried on the photosensitive drum 51 disposed on the upstream side. If the charge amount is small, color mixing tends to occur. Therefore, the charging ability of the magenta toner is less likely to be lower than the charging ability of the yellow toner, and the charging ability of the cyan toner is less likely to be lower than the charging ability of the yellow toner and the charging ability of the magenta toner. desirable. The toner charging capability here is measured by measuring the blow-off charge amount after rotating the developing roller 53 corresponding to each color by the same number of rotations.

  In the present specification and drawings, when the developing roller 53 corresponding to the color of the toner is specified, the symbols 53K, 53Y, 53M, and 53C are attached to black, yellow, magenta, and cyan, respectively. I decided to. Further, the yellow developing roller 53Y, the magenta developing roller 53M, and the cyan developing roller 53C are driven by a common drive source (not shown) provided in the apparatus main body 2, and can be rotated and stopped simultaneously. Yes.

  The transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50, and includes a driving roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel with a space in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyance belt 73 is in contact with each photosensitive drum 51. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 with the respective photosensitive drums 51 are arranged inside the conveyor belt 73 so as to face the respective photosensitive drums 51. The transfer roller 74 is applied with a transfer bias (transfer voltage) having a polarity different from the charging polarity of the toner by constant current control during transfer.

  The fixing unit 80 is disposed on the rear side of each process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 30 configured as described above, in the color printing mode (multi-color mode), first, the surface of each photosensitive drum 51 is uniformly charged by each scorotron charger 52 and then each LED. The unit 40 is exposed. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 51. Further, the toner in the toner storage chamber 55 is supplied to the developing roller 53 via the supply roller 54 and enters between the developing roller 53 and the layer thickness regulating blade 57 to form a thin layer having a certain thickness. Supported on. The toner in the toner storage chamber 55 is agitated by an agitator (not shown) when the developing roller 53 rotates.

  The toner carried on the developing roller 53 is supplied from the developing roller 53 to the electrostatic latent image formed on the photosensitive drum 51 as the developing roller 53 rotates in contact with the photosensitive drum 51. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 51.

  Then, the sheet S supplied onto the conveyor belt 73 passes between each photosensitive drum 51 and each transfer roller 74 disposed inside the conveyor belt 73, so that the sheet S is formed on each photosensitive drum 51. The transferred toner image is transferred onto the paper S. Further, as the sheet S passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the sheet S is thermally fixed.

  The paper discharge unit 90 includes a paper discharge-side transport path 91 formed so as to extend upward from the exit of the fixing unit 80 and reverse forward, and a plurality of pairs of transport rollers 92 that transport the paper S. . The sheet S on which the toner image has been transferred and heat-fixed is transported along a paper discharge side transport path 91 by a transport roller 92, discharged outside the apparatus main body 2, and accumulated in the paper discharge tray 4.

The control unit 100 includes a CPU, RAM, ROM, and the like (not shown), and is disposed at an appropriate position in the apparatus main body 2. The control unit 100 is configured to determine and notify the replacement timing of the developing cartridge 56.
In the following description, a magenta photoconductor drum 51M as an example of the first photoconductor, and a cyan photoconductor drum as an example of the second photoconductor disposed downstream of the first photoconductor in the transport direction of the paper S. An example of 51C will be described. Accordingly, as an example of the first developer carrying member, a magenta developing roller 53M that carries magenta (first color) toner, and as an example of the first cartridge, a magenta developing cartridge 56M that contains magenta toner. As an example of the second developer carrying member, a cyan developing roller 53C carrying cyan (second color) toner, and as an example of the second cartridge, a cyan developing cartridge 56C containing cyan toner. An example will be described.

<Detailed configuration of control unit>
As shown in FIG. 2, the control unit 100 mainly includes a rotation speed estimation unit 110, a determination unit 130, a notification unit 140, and a storage unit 190.

  The rotational speed estimating means 110 is a means for estimating the cumulative rotational speed NR1 of the magenta developing roller 53M and the cumulative rotational speed NR2 of the cyan developing roller 53C. Here, the cumulative rotational speed NR1 of the magenta developing roller 53M is an example of a first value that increases with the rotation of the magenta developing roller 53M after the magenta developing cartridge 56M is mounted on the apparatus main body 2. The cumulative rotation speed NR2 of the cyan developing roller 53C is an example of a second value that increases with the rotation of the cyan developing roller 53C after the cyan developing cartridge 56C is attached to the apparatus main body 2.

  The rotation speed estimation unit 110 counts the number of rotations of the developing roller 53 provided in the developing cartridge 56 since the development cartridge 56 is replaced, and outputs information on the counted number of rotations to the storage unit 190. It is configured. The rotational speed estimation means 110 resets the cumulative rotational speed NR1 of the magenta developing roller 53M when the magenta developing cartridge 56M is replaced, and accumulates the cyan developing roller 53C when the cyan developing cartridge 56C is replaced. It is configured to reset the rotational speed NR2. The reset timing may be when the old developing cartridge 56 is removed or when a new developing cartridge 56 is attached.

  The storage unit 190 is a unit that stores the cumulative rotational speed NR1 of the magenta developing roller 53M and the cumulative rotational speed NR2 of the cyan developing roller 53C based on the output of the rotational speed estimating unit 110. The storage unit 190 also stores a first threshold Th1 and a second threshold Th2.

  Based on the accumulated rotational speed NR1 of the magenta developing roller 53M and the cumulative rotational speed NR2 of the cyan developing roller 53C stored in the storage means 190, the judging means 130 determines the magenta developing cartridge 56M and the cyan developing cartridge 56C. It is a means for determining the replacement time. Specifically, as shown in FIG. 3A, the determination unit 130 determines that the magenta developing cartridge 56M when the cumulative rotational speed NR1 of the magenta developing roller 53M exceeds a preset first threshold Th1. Is determined to be time for replacement. Further, when the cumulative rotation speed NR2 of the cyan developing roller 53C exceeds a preset second threshold Th2, it is determined that it is time to replace the cyan developing cartridge 56C. In the present embodiment, the second threshold value Th2 is always set to a value smaller than the first threshold value Th1, for example, a value that is 1 to 2% smaller than the first threshold value Th1.

  By the way, when the second threshold Th2 is always set to a value smaller than the first threshold Th1, as shown in FIG. 3B, the replacement timing of the cyan developing cartridge 56C is changed soon after the replacement of the magenta developing cartridge 56M. May be. If only the magenta developing cartridge 56M is replaced at this time, the magenta toner is renewed, while the cyan toner is deteriorated, so that there is a possibility of color mixing. Therefore, the determination unit 130 is configured to calculate the difference between the second threshold Th2 and the cumulative rotation speed NR2 of the cyan development roller 53C when it is determined that the magenta development cartridge 56M is in the replacement period. . When the determination unit 130 determines that the difference between the second threshold Th2 and the cumulative rotation speed NR2 of the cyan developing roller 53C is within a predetermined value, that is, when it is determined that the replacement time of the cyan developing cartridge 56C is near, It is determined that the cyan developing cartridge 56C has been replaced. For example, by setting the predetermined value to about 30% of the second threshold Th2, it is possible to reduce color mixing in the cyan developing cartridge 56C.

  Returning to FIG. 2, when the determination unit 130 determines that the magenta development cartridge 56 </ b> M or the cyan development cartridge 56 </ b> C is at the replacement time, the determination unit 130 outputs information to that effect to the notification unit 140.

  The notification unit 140 is means for notifying a user who uses the color printer 1 of a message. In the present embodiment, the notification unit 140 is configured to notify the user of a message to that effect when it is determined that the magenta development cartridge 56M or the cyan development cartridge 56C is in the replacement period. In addition, as means for notifying a message, for example, a liquid crystal display that notifies a message by characters or pictures, a speaker that notifies a message by sound, a lamp that notifies a message by flashing light, or the like can be adopted.

<Description of operation of control unit>
The control operation of the control unit 100 configured as described above will be described with reference to FIG. In each flowchart, the control unit 100 repeatedly executes the processing from START to END.
First, the control unit 100 determines whether or not the cumulative rotational speed NR1 of the magenta developing roller 53M is greater than the first threshold Th1 (S10).

  If it is determined in step S10 that the cumulative rotational speed NR1 of the magenta developing roller 53M is not greater than the first threshold Th1 (No), the control unit 100 determines that the cumulative rotational speed NR2 of the cyan developing roller 53C is It is determined whether it is larger than the second threshold Th2 (S20).

  In step S20, when it is determined that the cumulative rotation speed NR2 of the cyan developing roller 53C is not larger than the second threshold Th2 (No), the control by the control unit 100 ends.

  On the other hand, when it is determined in step S20 that the cumulative rotation speed NR2 of the cyan developing roller 53C is larger than the second threshold Th2 (Yes), the control unit 100 notifies the replacement of the cyan developing cartridge 56C ( S30). When the cyan developing cartridge 56C is replaced, the control unit 100 resets the cumulative rotational speed NR2 of the cyan developing roller 53C stored in the storage unit 120 (S40), and the control is ended.

  If it is determined in step S10 that the accumulated rotational speed NR1 of the magenta developing roller 53M is greater than the first threshold Th1 (Yes), the control unit 100 accumulates the second threshold Th2 and the cyan developing roller 53C. It is determined whether or not the difference in the rotational speed NR2 is within a predetermined value (S50).

  If it is determined in step S50 that the difference between the second threshold Th2 and the cumulative rotation speed NR2 of the cyan developing roller 53C is within a predetermined value (Yes), the control unit 100 determines that the cyan developing cartridge 56C and magenta The replacement of the developing cartridge 56M is notified (S60). When the cyan developing cartridge 56C and the magenta developing cartridge 56M are exchanged, the accumulated rotational speed NR1 of the magenta developing roller 53M and the cumulative rotational speed NR2 of the cyan developing roller 53C stored in the storage unit 120 are reset. (S70), and the control ends.

  On the other hand, if it is determined in step S50 that the difference between the second threshold Th2 and the cumulative rotation speed NR2 of the cyan developing roller 53C is greater than a predetermined value (No), the control unit 100 sets the magenta developing cartridge 56M. The exchange is notified (S80). When the magenta developing cartridge 56M is replaced, the accumulated rotational speed NR1 of the magenta developing roller 53M stored in the storage unit 120 is reset (S90), and the control ends.

According to the above, the following effects can be obtained in the present embodiment.
Since the second threshold value Th2 is set to a value smaller than the first threshold value Th1, the cyan developing cartridge 56C is determined to be replaced at an earlier time than the magenta developing cartridge 56M. Therefore, the cyan developing cartridge 56C corresponding to the cyan photosensitive drum 51C disposed on the downstream side in the transport direction of the paper S from the magenta photosensitive drum 51M is used as the magenta developing cartridge 56C corresponding to the magenta photosensitive drum 51M. The cartridge can be replaced earlier than the cartridge 56M. As a result, it is possible to reduce color mixing that occurs when the magenta toner is newer than the cyan toner.

  Further, since the second threshold value Th2 is always smaller than the first threshold value Th1, the cyan developing cartridge 56C can be surely replaced before the magenta developing cartridge 56M.

  When it is determined that the magenta developer cartridge 56M is in the replacement period, the determination unit 130 determines that the difference between the second threshold Th2 and the cumulative rotation speed NR2 of the cyan developer cartridge 56C is within a predetermined value. Since it is determined that the cyan developing cartridge 56C has been replaced, it is possible to avoid replacing only the magenta developing cartridge 56M with a new one when the cyan toner is excessively deteriorated.

  Further, since the charging ability of cyan toner is less likely to be lower than the charging ability of magenta toner, it is possible to prevent cyan toner from being charged too much less than magenta toner.

  In the embodiment, the magenta photoconductor drum 51M is illustrated as an example of the first photoconductor, the cyan photoconductor drum 51C is illustrated as an example of the second photoconductor, the yellow photoconductor drum 51Y, and the magenta photoconductor. Of the drum 51M and the cyan photosensitive drum 51C, two relationships on the downstream side in the transport direction of the paper S have been described, but the present invention is not limited to this. For example, in any combination of yellow and magenta, magenta and cyan, and yellow and cyan, it is desirable to replace the developing cartridge on the downstream side in the transport direction of the paper S at an earlier time than the upstream developing cartridge.

  Specifically, as shown in FIG. 7A, the determination unit 130 determines that the yellow developing cartridge 56Y is in a state where the cumulative number of rotations of the yellow developing roller 53Y exceeds the yellow threshold Th1. It is determined that it is time for replacement. Further, when the cumulative rotational speed of the magenta developing roller 53M exceeds the magenta threshold Th2, the determining unit 130 determines that the magenta developing cartridge 56M is in the replacement period, and the cumulative rotational speed of the cyan developing roller 53C. However, when the cyan threshold Th3 is exceeded, it is determined that the cyan developing cartridge 56C is in the replacement period. Here, the cyan threshold Th3 is always set to a value smaller than the magenta threshold Th2, and the magenta threshold Th2 is always set to a value smaller than the yellow threshold Th1.

  With this configuration, the development cartridge disposed on the downstream side in the transport direction of the paper S is the development disposed on the upstream side of any combination of yellow, magenta, and cyan. It is replaced at an earlier time than the cartridge.

[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the present embodiment, in the control unit 100 having the same configuration as that of the first embodiment, the second threshold value Th2 is set to a value smaller than the first threshold value Th1 only during initial use. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 5, when the color printer 1 is used for the first time (at the time of initial use), the control unit 100 sets the second threshold Th2 to a value smaller than the first threshold Th1. The determination unit 130 is configured such that the second threshold value Th2 is set equal to the first threshold value Th1 after the first replacement of the cyan developing cartridge 56C.

  Further, when it is determined that it is time to replace the magenta developer cartridge 56M before the determination unit 130 determines that it is time to replace the cyan developer cartridge 56C for the first time due to some cause (for example, paper jam or the like) The determination unit 130 determines that the cyan developer cartridge 56C is also in the replacement period.

  Specifically, the storage unit 190 stores a flag (data) F2 indicating whether or not the cyan developer cartridge 56C has been replaced for the first time. This flag F2 is set to zero when the color printer 1 is initially used. When the determination unit 130 determines that it is time to replace the magenta developer cartridge 56M for the first time, the determination unit 130 determines whether the replacement time of the cyan developer cartridge 56C has been determined so far. If it has not been replaced, it is determined that the cyan developer cartridge 56C has also been replaced. Further, when the cyan developing cartridge 56C is replaced, the determination unit 130 sets the flag F2 to 1 (replaced).

Next, the control operation of the control unit 100 in the present embodiment will be described with reference to FIG.
First, the control unit 100 determines whether or not the cumulative rotational speed NR1 of the magenta developing roller 53M is greater than the first threshold Th1 (S10).

  If it is determined in step S10 that the cumulative rotational speed NR1 of the magenta developing roller 53M is not greater than the first threshold Th1 (No), the control unit 100 determines that the cumulative rotational speed NR2 of the cyan developing roller 53C is It is determined whether it is larger than the second threshold Th2 (S20).

  In step S20, when it is determined that the cumulative rotation speed NR2 of the cyan developing roller 53C is not larger than the second threshold Th2 (No), the control by the control unit 100 ends.

  On the other hand, when it is determined in step S20 that the cumulative rotation speed NR2 of the cyan developing roller 53C is larger than the second threshold Th2 (Yes), the control unit 100 notifies the replacement of the cyan developing cartridge 56C ( S30). When the cyan developing cartridge 56C is replaced, the flag F2 is set to 1 (S35), and the accumulated rotational speed NR2 of the cyan developing roller 53C stored in the storage unit 120 is reset (S40). Further, the control unit 100 sets the second threshold Th2 to a value equal to the first threshold Th1 (S45), and ends the control.

  If it is determined in step S10 that the cumulative rotation speed NR1 of the magenta developing roller 53M is greater than the first threshold Th1 (Yes), the control unit 100 determines whether or not the flag F2 is 1 (S55). ).

  When it is determined in step S55 that F2 is 1 (the cyan developing cartridge 56C has been replaced at least once) (Yes), the control unit 100 notifies the replacement of the magenta developing cartridge 56M ( S80). When the magenta developing cartridge 56M is replaced, the control unit 100 resets the accumulated rotational speed NR1 of the magenta developing roller 53M stored in the storage unit 120 (S90), and ends the control.

  On the other hand, when it is determined in step S55 that the flag F2 is not 1 (the cyan developing cartridge 56C has not been replaced since the initial use) (No), the control unit 100 determines that the magenta developing cartridge 56M and the cyan developing cartridge are not used. The replacement of the cartridge 56C is notified (S60). When the magenta developing cartridge 56M and the cyan developing cartridge 56C are exchanged, the flag F2 is set to 1 (S65). Further, the control unit 100 resets the cumulative rotational speed NR1 of the magenta developing roller 53M and the cumulative rotational speed NR2 of the cyan developing roller 53C (S70).

  According to the color printer 1 of the second embodiment as described above, the replacement frequency of the cyan developing cartridge 56C can be reduced as compared with the case where the second threshold Th2 is always smaller than the first threshold Th1. it can.

  Further, the control unit 100 stores in the storage unit 120 a flag F2 indicating whether or not the cyan developer cartridge 56C has been replaced for the first time, and the determination unit 130 is the first to replace the magenta developer cartridge 56M. If it is determined that the replacement timing of the cyan developing cartridge 56C has not been determined so far, it is determined that the cyan developing cartridge 56C is also the replacement timing. It is possible to prevent the toner cartridge from being replaced before the cyan developing cartridge 56C.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the second embodiment, only the replacement timing of the magenta developing cartridge 56M and the cyan developing cartridge 56C has been described, but the present invention is not limited to this. For example, as described in the modification of the first embodiment, the developing cartridge on the downstream side in the transport direction of the sheet S is the upstream developing cartridge in any combination of yellow and magenta, magenta and cyan, and yellow and cyan. It is desirable to replace it at an earlier time.

  Specifically, as shown in FIG. 7B, the determination unit 130 determines that the yellow developing cartridge 56Y is in a state where the cumulative number of rotations of the yellow developing roller 53Y exceeds the yellow threshold Th1. When it is determined that the replacement time is reached and the cumulative rotation speed of the magenta development roller 53M exceeds the magenta threshold Th2, it is determined that the magenta development cartridge 56M is the replacement time, and the cumulative rotation of the cyan development roller 53C. When the number exceeds the cyan threshold Th3, it is determined that the cyan developing cartridge 56C is in the replacement period.

  Here, at the initial use of the color printer 1, the magenta threshold Th2 is set to a value smaller than the yellow threshold Th1, and the cyan threshold Th3 is set to a value smaller than the magenta threshold Th2. The magenta threshold Th2 and the cyan threshold Th3 are set to values equal to the yellow threshold Th1 after the first replacement of the magenta developing cartridge 56M and the cyan developing cartridge 56C, respectively.

  With this configuration, the development cartridge 56 disposed on the downstream side in the transport direction of the paper S is disposed on the upstream side of any combination of yellow, magenta, and cyan. The developer cartridge 56 is replaced at an earlier time.

  In the embodiment, the cumulative rotation speed NR1 of the magenta developing roller 53M is exemplified as an example of the first value, and the cumulative rotation speed NR2 of the cyan developing roller 53C is illustrated as an example of the second value. The first value and the second value may be values that increase with the rotation of the magenta developing roller 53M and the cyan developing roller 53C. For example, the first value and the second value may each be the number of printed sheets.

  In the above-described embodiment, the developing cartridge 56 including the developing roller 53, the supply roller 54, the layer thickness regulating blade 57, and the toner storage chamber 55 is illustrated as an example of the cartridge, but the present invention is limited to this. It is not a thing. For example, the cartridge may be a developing cartridge (so-called toner box) that mainly has only the toner storage chamber 55 and is detachable from the apparatus main body 2 while the developing roller 53 remains in the apparatus main body 2.

  In the embodiment, the paper S is exemplified as the transfer medium. However, the present invention is not limited to this, and the transfer medium may be, for example, an intermediate transfer belt. In the image forming apparatus using the intermediate transfer belt, the toner images on the respective photosensitive drums 51 are sequentially superimposed and transferred onto the intermediate transfer belt, and then transferred onto the paper S from the intermediate transfer belt.

  In the above embodiment, the color printer 1 is exemplified as the image forming apparatus. However, the present invention is not limited to this, and the present invention can also be applied to a multifunction machine or a copier.

1 Color Printer 51 Photosensitive Drum 51C Cyan Photosensitive Drum 51M Magenta Photosensitive Drum 51Y Yellow Photosensitive Drum 53 Developing Roller 53C Cyan Developing Roller 53M Magenta Developing Roller 53Y Yellow Developing Roller 56 Developing Cartridge 56C Cyan Developing Cartridge 56M Developing cartridge for magenta 56Y Yellow developing cartridge 100 Control unit 110 Speed estimation means 120 Storage means 130 Determination means 140 Notification section F2 flag NR1 Cumulative rotational speed NR2 Cumulative rotational speed S Paper Th1 First threshold Th2 Second threshold

Claims (7)

The device body;
A first cartridge containing a developer of a first color other than black and configured to be replaceable with respect to the apparatus main body;
A first developer carrying member carrying the developer of the first color;
A first photoreceptor to which developer is supplied from the first developer carrier;
A second cartridge containing a developer of a second color other than black and configured to be replaceable with respect to the apparatus main body;
A second developer carrier for carrying the second color developer;
A second photoconductor disposed downstream of the first photoconductor in the moving direction of the transfer medium and supplied with a developer from the second developer carrier;
A first value that increases with the rotation of the first developer carrier after the first cartridge is mounted on the apparatus main body, and the second development after the second cartridge is mounted on the apparatus main body. Storage means for storing a second value that increases with rotation of the agent carrier;
When the first value exceeds the first threshold, it is determined that the first cartridge is in a replacement period, and when the second value exceeds the second threshold, the second cartridge Determination means for determining that it is time to replace the cartridge,
The image forming apparatus, wherein the second threshold value is set to a value smaller than the first threshold value at least during initial use.   The image forming apparatus according to claim 1, wherein the second threshold value is always set to a value smaller than the first threshold value.   The image forming apparatus according to claim 1, wherein the second threshold value is set to a value equal to the first threshold value after the first replacement of the second cartridge. The storage means stores data indicating whether the second cartridge has been replaced;
When it is determined that it is time to replace the first cartridge for the first time, the determination means determines that it is time to replace the second cartridge if the replacement of the second cartridge has not been performed so far. The image forming apparatus according to claim 3.   When the determination unit determines that it is time to replace the first cartridge, and the difference between the second threshold value and the second value stored in the storage unit is within a predetermined value, The image forming apparatus according to claim 1, wherein the second cartridge is determined to be in a replacement time.   The charging ability of the developer of the second color is less likely to be lower than the charging ability of the developer of the first color. Image forming apparatus. The first value is a cumulative rotational speed of the first developer carrier.
The image forming apparatus according to claim 1, wherein the second value is a cumulative number of rotations of the second developer carrying member.

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