JP6260968B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a printing apparatus, and more particularly to an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile.

  Conventionally, in-line color image forming apparatuses using an electrophotographic system, the following transfer system is known. That is, this is a transfer system in which toner images of four colors of yellow, magenta, cyan, and black carried on a photosensitive drum are primarily transferred to an intermediate transfer belt and then secondarily transferred to a recording sheet. In such a color image forming apparatus, a configuration is known in which a cleaning blade for scraping off toner remaining after transfer is in contact with the intermediate transfer belt. Here, if the state in which the amount of toner entering the cleaning blade is small continues, the lubricity (slip degree) between the cleaning blade and the intermediate transfer belt is lowered, and cleaning failure occurs. Furthermore, the cleaning blade may be turned over as the state progresses.

  Therefore, in Patent Document 1, toner is forcibly supplied to the cleaning blade from the cartridge through the photosensitive drum and the conveyance belt outside the image forming area at a predetermined timing. Thus, a method for maintaining the lubricity between the cleaning blade and the conveyor belt has been proposed. Further, Patent Document 2 proposes a technique for supplying a small amount of toner little by little to a cleaning blade without transferring it to recording paper between images of continuous printing.

JP 2001-282010 A JP 2011-064741 A

  However, in the method of Patent Document 2, the toner image on the intermediate transfer belt and the secondary transfer roller are in direct contact with each other, and a configuration in which the secondary transfer roller can be brought into contact with and separated from the intermediate transfer belt is required. Further, when the secondary transfer roller is not configured to be able to contact and separate from the intermediate transfer belt, the toner adheres to the secondary transfer roller, and the toner adheres to the back surface of the recording paper to be conveyed next. This is called recording paper back contamination. To prevent this recording paper from becoming dirty, when the toner image formed on the intermediate transfer belt passes through the transfer nip portion in order to maintain the lubricity of the cleaning blade, the secondary transfer roller has the same polarity as the toner. Measures such as applying a bias are necessary. Furthermore, when continuous image formation is performed while maintaining the image formation speed, a technique is also required in which a low-density toner image is formed on the intermediate transfer belt to suppress toner adhesion to the secondary transfer roller. It becomes. Therefore, a small amount of toner supplied to the cleaning blade between images needs to be prepared by the image controller as an image whose density is correctly controlled in order to suppress adhesion of the toner to the secondary transfer roller. In addition, the image controller needs to prepare an optimum image according to an instruction from the image forming engine according to the state of the cleaning blade and the image forming state. Here, it is assumed that the pattern of the supplied toner image suddenly changes due to the type of image to be formed, the state of the cleaning blade, the installation environment of the image forming apparatus, and the change with time.

  However, in order to obtain an optimum image for protecting the cleaning blade by the image controller, an image processing time and a development time to the image memory are required. The image controller may not be able to react immediately to a sudden request from the image forming engine, resulting in a downtime due to waiting for the processing time of the image controller.

  The present invention has been made under such circumstances, and an object thereof is to maintain the lubricity between the carrier and the cleaning means while suppressing a decrease in productivity.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) A photosensitive member on which an electrostatic latent image is formed, a developing unit that develops the electrostatic latent image formed on the photosensitive member with toner, and a toner image or a recording material formed by the developing unit. A carrier; a cleaning unit that contacts the carrier to clean the carrier; a controller that processes input image information; and the photoconductor and the developing unit based on image information processed by the controller And an image forming apparatus capable of operating in a mode in which toner is supplied to the cleaning means by forming a toner image on a non-image area of the carrier. said control means, it said in forming a toner image on the non-image area, or to form a first toner image based on image information processed by the controller, the controller A first time required to determine whether to form a different second toner image to form the first toner image and not based on the processed image information, said first toner image by, A second time required to form the second toner image is obtained, and the toner image that requires the shorter of the first time and the second time is selected. Image forming apparatus.

  According to the present invention, it is possible to maintain the lubricity between the carrier and the cleaning unit while suppressing a decrease in productivity.

FIG. 3 is a cross-sectional view of a main part illustrating the configuration of the image forming apparatus according to the first exemplary embodiment. Explanatory drawing of the toner supply mode of Embodiment 1. Toner supply timing chart of Embodiment 1 Flowchart for explaining processing for selecting a supply toner image according to the first exemplary embodiment. Explanatory drawing of productivity according to transfer material type of Example 2, toner supply timing chart 10 is a flowchart for describing processing for selecting a supply toner image according to the second embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail by way of examples with reference to the drawings.

  In the first exemplary embodiment, when a pattern change of a supplied toner image occurs with respect to the formation of an image (hereinafter referred to as a supplied toner image) for supplying toner for protecting a cleaning blade of an intermediate transfer belt, which is a carrier, which will be described later. Control as follows. In other words, when changing the pattern of the supplied toner image, which is a toner image for lubrication, by the image controller (hereinafter referred to as the controller) and by the image forming engine, the selection is made so that the downtime of the image forming apparatus is minimized. To do.

[Configuration of Image Forming Apparatus]
FIG. 1A is a cross-sectional view illustrating a configuration of a main part of the image forming apparatus according to the present exemplary embodiment. The image forming apparatus includes four electrophotographic photosensitive drums (hereinafter simply referred to as photosensitive drums) 2a, 2b, 2c, and 2d for yellow, magenta, cyan, and black, which are image carriers arranged side by side. Yes. Here, the subscripts a, b, c, and d represent yellow, magenta, cyan, and black, respectively, and are omitted unless necessary. Around each photosensitive drum 2, a charging roller 7 as a charging unit, a developing device 3 as a developing unit, and a cleaning unit are sequentially arranged from the upstream side in the rotation direction of the photosensitive drum 2 (the arrow direction (clockwise direction in the figure)). A certain cleaning device 5 is arranged.

  The charging roller 7 uniformly charges the surface of the photosensitive drum 2. The surface of the photosensitive drum 2 uniformly charged by the charging roller 7 is irradiated with a laser beam from the exposure device 1 serving as an exposure unit based on image information to form an electrostatic latent image. The developing device 3 causes each color toner (developer) to adhere to the surface of the photosensitive drum 2 on which the electrostatic latent image is formed, and visualizes it as a toner image. The cleaning device 5 removes the toner remaining on the surface of the photosensitive drum 2 after transfer and collects it in the remaining toner container. An intermediate transfer belt 10 to which a toner image formed on the surface of the photosensitive drum 2 is transferred is stretched by a driving roller 11, a tension roller 12 and a driven roller 13 at a position facing the photosensitive drum 2. A secondary transfer roller 22 is disposed at a position facing the driving roller 11 with the intermediate transfer belt 10 interposed therebetween.

  The toner image formed on each photosensitive drum 2 is transferred to the intermediate transfer belt 10 by the action of the primary transfer roller 4 serving as a primary transfer unit (referred to as primary transfer). On the other hand, the recording material 30 fed from the feeding cassette by the pickup roller 31 is separated and fed one by one by a separating means (not shown). Next, the recording material 30 is sent to the registration roller pair 33 and is conveyed between the intermediate transfer belt 10 and the secondary transfer roller 22 by the registration roller pair 33 at a predetermined timing. Then, the toner image primarily transferred to the intermediate transfer belt 10 by the action of the secondary transfer roller 22 is transferred to the recording material 30 (referred to as secondary transfer). Here, a nip portion formed by the driving roller 11 and the secondary transfer roller 22 is a secondary transfer nip portion. The recording material 30 onto which the toner image has been transferred, after the toner image is fixed by a fixing device 34 as fixing means, is conveyed by a discharge roller pair 35 and discharged onto a discharge tray 36 provided at the top of the apparatus main body. Is done.

  After the secondary transfer is completed, the toner remaining on the intermediate transfer belt 10 (on the carrier) is scraped off by an intermediate transfer belt cleaning blade 27 which is a cleaning unit disposed in contact with the intermediate transfer belt 10. Thus, the remaining toner is removed from the surface of the intermediate transfer belt 10 to be cleaned and collected. In this embodiment, the intermediate transfer belt cleaning blade 27 is an elastic cleaning blade made of urethane rubber. The image forming apparatus according to the present exemplary embodiment can be operated in a mode in which a supply toner image for maintaining lubricity between the intermediate transfer belt 10 and the intermediate transfer belt cleaning blade 27 is formed in a non-image area of the intermediate transfer belt 10. is there. Here, if the state where the amount of toner entering the intermediate transfer belt cleaning blade 27 is small, the lubricity (slip degree) between the intermediate transfer belt cleaning blade 27 and the intermediate transfer belt 10 is lowered, and cleaning failure occurs. To do. Furthermore, the cleaning blade may be turned over as the state progresses. Therefore, toner is supplied to maintain the lubricity between the intermediate transfer belt cleaning blade 27 and the intermediate transfer belt 10.

[Block diagram of image forming apparatus]
FIG. 1B is a block diagram illustrating an example of a control unit configuration of the image forming apparatus according to the present exemplary embodiment. The controller 650 connected to the host computer 660 issues an image formation command to the image formation engine 620 via the video interface 640. The controller 650 includes an image processing unit 651, an image memory 652, and a storage unit 653, which are image processing means. The image processing unit 651 converts the image transmitted from the host computer 660 into image information that can be received by the image forming engine 620. The image memory 652 is a memory for accumulating image information processed by the image processing unit 651. The storage unit 653 is a storage unit for storing internal information of the controller 650 itself, sample images held in advance by the controller 650, and the like. When image formation is actually performed, image information that has been subjected to image processing by the image processing unit 651 is developed in the image memory 652. In synchronization with the image output timing from the image forming engine 620, the image information developed in the image memory 652 is output to the image forming engine 620 via the video interface 640.

  The image forming engine 620 includes a CPU 600 and an image forming unit 630. The image forming unit 630 includes a process cartridge 631, an exposure device 1, a primary transfer roller 4, a secondary transfer roller 22, an intermediate transfer belt cleaning blade 27, and a fixing device 34. Further, the process cartridge 631 includes a charging roller 7, a developing device 3, and a cleaning device 5. The CPU 600 has a ROM 601 and a RAM 602. The CPU 600 executes specific image formation control while controlling each unit of the image forming unit 630 using the RAM 602 as a work area based on various control programs stored in the ROM 601. In the present embodiment, it has been described that various processes are performed based on the process of the CPU 600. However, a part or all of the process performed by the CPU 600 may be performed by an ASIC that is an integrated circuit.

[Toner supply mode with the same pattern]
FIG. 2A is a view for explaining the operation of a mode for supplying toner for maintaining lubricity to the intermediate transfer belt cleaning blade 27 (hereinafter referred to as toner supply mode). Hereinafter, a toner image formed during the toner supply mode operation and not transferred to the recording material 30 is referred to as a supply toner image, and a toner image transferred to the recording material 30 is referred to as a real image. 2A and 2I show a real image and a supplied toner image transferred onto the intermediate transfer belt 10. FIG. 2A and 2I show the real image / TOP signal output from the image forming engine 620 to the controller 650. FIG. 2A and FIG. 2I are output from the image forming engine 620 to the controller 650. The / TOP signal of the supplied toner image is shown. The output timing of the / TOP signal in FIGS. 2 (a) (ii) and 2 (a) (iii) is drawn in accordance with the real image and the supplied toner image in FIGS. 2 (a) (i). Further, the supplied toner image and the real image are arranged in the order of image formation from left to right in FIG. That is, on the intermediate transfer belt 10, a real image of page 1 (Page 1), a supplied toner image of pattern A, a real image of page 2 (Page 2), a supplied toner image of pattern A, a real image of page 3 (Page 3), and a pattern A The supplied toner images are transferred in this order.

  In FIG. 2A, the supply toner image is defined as a pattern A for convenience, and the supply toner image is formed on the non-image area of the real image of three sheets (1 page (Page 1) to 3 pages (Page 3)). Is assumed. Specifically, in order to supply the toner uniformly to the intermediate transfer belt cleaning blade 27, a halftone image having the maximum developable area width is formed in the non-image area. Here, the controller 650 can accurately control the density of the image, and the supplied toner image of the pattern A generated by the controller 650 (same for pattern B described later) is such that the secondary transfer roller 22 is not soiled. Generated as a density image. The non-image area is an area between a real image and a real image that is a toner image transferred to the recording material 30, that is, an area corresponding to a space between the recording material 30 and the recording material 30 (between sheets) or one page ( The area up to the tip of the real image of Page 1). The width means a length in a direction orthogonal to the moving direction of the intermediate transfer belt 10. The supplied toner image may be formed by any one of the four color process cartridges 631.

  The image forming engine 620 outputs a / TOP signal to the controller 650 via the video interface 640 at a timing when the image forming conditions are satisfied. As a result, the controller 650 outputs image information corresponding to a real image from the image memory 652 to the image forming engine 620. The controller 650 outputs image information corresponding to the supplied toner image from the image memory 652 to the image forming engine 620 in synchronization with the / TOP signal from the image forming engine 620. In this embodiment, the supplied toner image of the pattern A (the same applies to the pattern B described later) is stored in the storage unit 653 in the controller 650 in advance.

  Here, when the real image passes through the secondary transfer nip portion, a secondary transfer voltage having a polarity different from that of the toner is applied to the secondary transfer roller 22, so that the toner image on the intermediate transfer belt 10 ( Real image) is transferred. On the other hand, the supplied toner image formed in the non-image area is a toner image for maintaining the lubricity of the intermediate transfer belt cleaning blade 27 and is not a toner image for transferring to the recording material 30. Therefore, when the supplied toner image passes through the secondary transfer nip portion, the amount of toner adhering to the secondary transfer roller 22 is suppressed by applying a secondary transfer voltage having the same polarity as the toner. In addition, when the supplied toner image is a sufficiently low density toner image, the application of the secondary transfer voltage may be stopped. Thereafter, the supplied toner image of pattern A is supplied to the intermediate transfer belt cleaning blade 27, and a good slipping state is maintained between the intermediate transfer belt 10 and the intermediate transfer belt cleaning blade 27 due to the lubricating effect of the toner. Then, it is possible to prevent the occurrence of cleaning failure.

[Toner supply mode with different patterns]
FIG. 2B shows an example in which the supplied toner image is formed with a pattern B different from the pattern A after the second page (Page 2), and FIGS. 2B to 2B are shown in FIG. Corresponds to FIG. 2 (a) (i) to FIG. 2 (a) (iii). There are various reasons for changing the supplied toner image. For example, the image density of the real image is low, and the toner remaining after secondary transfer of the real image and the supplied toner image of pattern A cannot maintain lubricity, and the intermediate transfer belt. It is assumed that the cleaning blade 27 cannot be protected. Further, it is assumed that the pattern is changed when a process condition different from the current supply toner image is selected depending on the remaining amount of toner in the process cartridge 631 and the toner deterioration state.

  Similar to FIG. 2A, the image information of the real image and the supplied toner image is output from the image memory 652 of the controller 650 in synchronization with the / TOP signal output from the image forming engine 620. If the image forming engine 620 determines that the supplied toner image should be changed from the pattern A to the pattern B in the middle of the second page (Page 2) for the reason described above, the image forming engine 620 changes the pattern to the controller 650. Request. In this embodiment, a case where the supplied toner image is changed to the pattern B having a size larger than the pattern A in the moving direction of the belt 10 in order to supply more toner by the intermediate transfer belt cleaning blade 27 will be described.

  On the other hand, the controller 650 that has received the pattern change request from the image forming engine 620 discards the supplied toner image of the pattern A already developed in the image memory 652. Then, the controller 650 performs image processing on the supplied toner image data of the pattern B stored in the storage unit 653 by the image processing unit 651, and develops it in the image memory 652. The image forming engine 620 outputs a / TOP signal to the controller 650 at the timing of receiving the completion of switching from the controller 650 to the pattern B, and the controller 650 starts outputting the supplied toner image from the image memory 652. For this reason, the image formation start of the supplied toner image of the pattern B is delayed. The wide opening between the real image on page 2 (Page 2) and the supply toner image of pattern B in FIGS. 2B and 2I indicates that the start of image formation of the supply toner image of pattern B is delayed. ing. That is, from the output of the / TOP signal of the real image of page 2 (Page 2) shown in FIGS. 2B and 2I to the output of the / TOP signal of the supply toner image of pattern B shown in FIG. The time is longer than in the case of FIG.

[Toner supply mode in image forming engine]
The image forming engine 620 can create the supplied toner image itself. When the supply toner image is generated by the image forming engine 620, the density of the supply toner image may not be accurately controlled as compared with the case where the supply toner image is generated by the controller 650. However, the image forming engine 620 can easily form an electrostatic latent image on the photosensitive drum 2 by, for example, completely turning on the laser beam with the exposure device 1. Here, the full lighting of the laser beam means that the laser of the exposure device 1 is lit at a maximum intensity for a predetermined time. As described above, when the image forming engine 620 itself prepares the supply toner image, it does not require time for preparing the supply toner image as described with reference to FIG. It becomes possible. At this time, the supplied toner image generated by the image forming engine 620 is not based on the image information from the controller 650.

  Here, FIG. 2C is an example when the supplied toner image is formed with a pattern C different from the pattern A only after the second page (Page 2). Pattern C in FIG. 2C is a supply toner image formed by the image forming engine 620 turning on the laser beam completely, and is formed with a toner amount equivalent to the toner amount supplied by the supply toner image of pattern B. Has been. For this reason, Pattern B and Pattern C have the same effect as a lubricant. Since the supply toner image of the pattern C is formed by the image forming engine 620, the image formation start of the supply toner image of the pattern C is not delayed as shown in FIG. That is, from the output of the / TOP signal of the real image of page 2 (Page 2) shown in FIGS. 2C and 2I, the leading edge of the supplied toner image of the pattern C shown in FIGS. The time to the left end) is shorter than in the case of FIG. Since the pattern C is formed by the image forming engine 620 itself, it is not necessary to output the / TOP signal for the pattern C to the controller 650 as shown in FIG. 2 (c) (iii). Further, when returning to the supplied toner image of pattern A on page 3 (Page 3), the controller 650 has not discarded the image information of pattern A developed in the image memory 652, and therefore the pattern A at the same timing as page 1 (Page 1). The supplied toner image can be formed.

  However, when the laser beam is fully lit, the supply toner image has the maximum density. Therefore, even if a secondary transfer voltage having the same polarity as that of the toner is applied to the secondary transfer roller 22, the supply toner image is secondary. It adheres to the transfer roller 22. For this reason, after the supplied toner image passes through the secondary transfer nip portion, it is necessary to clean the secondary transfer roller 22 by alternately applying a positive voltage and a negative voltage to the secondary transfer roller 22. On the other hand, after the supplied toner images of the pattern A and the pattern B pass through the secondary transfer nip portion, it is not necessary to perform the cleaning process of the secondary transfer roller 22. The image forming apparatus includes a power source that is an application unit (not shown) that can apply a positive voltage and a negative voltage to the secondary transfer roller 22. In FIG. 2C, the wide opening between the supplied toner image of pattern C and page 3 (Page 3) indicates that the secondary transfer roller 22 is being cleaned. That is, the time from the output of the / TOP signal of the real image of page 2 (Page 2) shown in FIG. 2C (ii) to the output of the / TOP signal of the real image of page 3 (Page 3) is as shown in FIG. It is longer than the case.

[Toner supply timing chart]
FIG. 3 is a timing chart showing the control of this embodiment. FIG. 3A is a diagram illustrating the operation timing of the controller 650, and FIG. 3B is a diagram illustrating the operation timing of the image forming engine 620. 3C shows a real image / TOP signal output from the image forming engine 620 to the controller 650, and FIG. 3D shows a supplied toner image / TOP signal output from the image forming engine 620 to the controller 650. Show. FIG. 3E shows a toner image formed on the intermediate transfer belt 10 when the pattern B supply toner image is adopted, and FIG. 3F shows a case where the pattern C supply toner image is adopted. FIG. 2 is a diagram illustrating a toner image formed on an intermediate transfer belt. In FIG. 3E, since the processing time by the controller 650 is required, the formation of the supply toner image of the pattern B is delayed, and the formation is performed at the timing when the supply toner image of the pattern A is formed (also referred to as productivity). Since this is not possible, the pattern B is represented with a cross.

  The toner supply mode described with reference to FIG. 2 is utilized for the supplied toner image for maintaining the lubricity between the intermediate transfer belt 10 and the intermediate transfer belt cleaning blade 27. In this embodiment, when a situation occurs in which the supplied toner image is changed from the pattern A to the pattern B, the following determination is made. That is, it is determined from the viewpoint of downtime of the image forming apparatus whether the pattern B generated by the controller 650 should be adopted or the pattern C generated by the image forming engine 620 should be adopted. As a result, this embodiment proposes a method capable of supplying toner while maintaining high productivity.

ここで、Ｔ＿ｓｐ、Ｔ＿ｐａｔ＿Ｂ、Ｔ＿ｐａｔ＿Ｃ、Ｔ＿ｃｌｎは、予めこれらの時間を測定しておくことにより、既知の値として例えばＲＯＭ６０１等に保持しておく。また、Ｔ＿ｃｈｇ、Ｔ＿ｄｌｙは、コントローラ６５０の処理時間に依存するため、実像の／ＴＯＰ信号を起点として不図示のタイマ等により測定される。更に、Ｔ＿ｅｖｅも、実像の／ＴＯＰ信号を起点として不図示のタイマ等により測定される。尚、測定された情報は、例えばＲＡＭ６０２等に保存される。 Table 1 shows the definitions of the times described in the timing chart of FIG.

Here, T_sp, T_pat_B, T_pat_C, and T_cln are stored in the ROM 601 or the like as known values by measuring these times in advance. Since T_chg and T_dly depend on the processing time of the controller 650, they are measured by a timer (not shown) starting from the real image / TOP signal. Further, T_eve is also measured by a timer or the like (not shown) starting from the real image / TOP signal. Note that the measured information is stored in the RAM 602 or the like, for example.

Here, when the / TOP signal of page 2 (Page 2) is used as a starting point and the pattern B is used for the supplied toner image, the formation of the supplied toner image of the pattern B on the intermediate transfer belt 10 is completed. Is expressed by (Equation 1).
T_eve + T_chg + T_pat_B (Expression 1)
On the other hand, when the pattern C is used for the supplied toner image, the time until the image formation of the supplied toner image of the pattern C on the intermediate transfer belt 10 is completed and the cleaning of the secondary transfer roller 22 is completed is ( It is represented by Formula 2).
T_sp + T_pat_C + T_cln (Expression 2)

  The CPU 600 of the image forming engine 620 calculates a difference T_diff1 (= (Expression 1) − (Expression 2)) obtained by subtracting the time of (Expression 2) from the time of (Expression 1). When the time difference T_diff1 is greater than 0, the time obtained by (Equation 1) is longer, and therefore the image forming apparatus 620 forms the supplied toner image of the pattern C and the downtime of the image forming apparatus becomes smaller. On the other hand, when the time difference T_diff1 is 0 or less, the time obtained by (Equation 1) is shorter, so that the controller 650 forms the supplied toner image of the pattern B and the downtime of the image forming apparatus becomes smaller.

[Supply toner image selection process]
In FIG. 4, whether the pattern B generated by the controller 650 should be adopted or the pattern C generated by the image forming engine 620 should be generated from the real image / TOP signal as a starting point from the viewpoint of downtime of the image forming apparatus. It is a flowchart to judge. In the case of continuous printing in which two or more pages are printed, the process of FIG. 4 is executed for each page starting from the / TOP signal. The image forming engine 620 outputs a real image / TOP signal, starts a timer (not shown), and starts the following processing. In step (hereinafter referred to as “S”) 100, the image forming engine 620 determines whether or not a change in the supplied toner image pattern has occurred due to the above-described reason, and determines that no change in the supplied toner image pattern has occurred. If so, the process of S100 is repeated. If the image forming engine 620 determines in S100 that the pattern change of the supplied toner image has occurred, the process proceeds to S101. In step S101, the image forming engine 620 obtains values of T_chg, T_dly, and T_eve by referring to a timer (not shown), reads other time information held in the ROM 601, and described above (Formula 1) and (Formula 2). ) To calculate the time difference T_diff1. In step S102, the image forming engine 620 determines whether the time difference T_diff1 calculated in step S101 is greater than zero.

  In this embodiment, since (Equation 1) and (Equation 2) are calculated after measuring the times T_chg and T_dly, the result of the determination in S102 is reflected from the next page (for example, page 3). Become. For this reason, the time estimated for the times T_chg and T_dly may be stored in the ROM 601 as an initial value in advance. Then, (Formula 1) and (Formula 2) may be calculated using the initial values stored in the ROM 601 at the timing when the image forming engine 620 transmits the supply toner image change request to the controller 650. In this case, the determination result of S102 is reflected from the second page. Further, when the pattern B is adopted as a result of the determination in S102, the times T_chg and T_dly are measured by a timer, and (Equation 1) and (Equation 2) are calculated next (for example, the third page). In this case, the actually measured times T_chg and T_dly may be used.

  If the image forming engine 620 determines in S102 that the time difference T_diff1 is greater than 0 (T_diff1> 0), the process proceeds to S103. In this case, when the image forming engine 620 forms the supply toner image of the pattern C, the downtime of the image forming apparatus is reduced. In S103, the image forming engine 620 determines whether or not the time T_sp has elapsed by referring to a timer value (not shown). If it is determined that the time T_sp has not elapsed, the process returns to S103. . If the image forming engine 620 determines in S103 that the time T_sp has elapsed, that is, the time T_sp, which is the generation timing of the supplied toner image when the real image formation is completed and normal productivity is maintained, has elapsed. At the timing, the process proceeds to S104. In step S <b> 104, the image forming engine 620 forms a supply toner image having the pattern C on the intermediate transfer belt 10. In S105, the image forming engine 620 applies the positive voltage and the negative voltage alternately to the secondary transfer roller 22 after the formation of the supplied toner image is completed and the supplied toner image has passed through the secondary transfer nip portion. The transfer roller 22 is cleaned.

  On the other hand, if the image forming engine 620 determines in S102 that the time difference T_diff1 is 0 or less (T_diff1 ≦ 0), the process proceeds to S106. In step S <b> 106, the image forming engine 620 transmits a supply toner image change request to the controller 650 via the video interface 640. When the controller 650 receives the supply toner image change request from the image forming engine 620, the controller 650 discards the supply toner image of the pattern A already developed in the image memory 652. Thereafter, the controller 650 performs image processing on the data related to the supplied toner image of the pattern B stored in the storage unit 653 by the image processing unit 651, and develops the data in the image memory 652. Then, the controller 650 notifies the image forming engine 620 via the video interface 640 that the change of the supplied toner image to the pattern B is completed.

  In S107, the image forming engine 620 determines whether or not a notification indicating that the supply toner image change has been completed is received from the controller 650. If it is determined that the notification has not been received, the process of S107 is repeated. If the image forming engine 620 determines in step S107 that the supply toner image change completion notification has been received from the controller 650, the process proceeds to step S108. In step S <b> 108, the image forming engine 620 outputs a / TOP signal for forming the supply toner image with the pattern B, and forms the supply toner image with the pattern B.

  As described above, according to this embodiment, it is possible to maintain the lubricity between the carrier and the cleaning unit while suppressing the decrease in productivity.

  In the second embodiment, whether to use the pattern A generated by the controller 650 as the toner supply mode or to generate the pattern C generated by the image forming engine 620 according to the type of transfer material and the number of images formed, Judgment is made from the viewpoint of productivity of the image forming apparatus. Thus, in this embodiment, a method for supplying toner while maintaining high productivity will be described. In this embodiment, the description of the entire image forming apparatus is omitted because it overlaps with that of the first embodiment, and the same reference numerals are used for the same components and the same means. The type of transfer material is determined based on input from an operation unit (not shown), information notified from the host computer 660, or a determination result of a recording material determination sensor (not shown). Further, the number of formed images is also based on information input from an operation unit (not shown) or information notified from the host computer 660.

[Toner supply according to the type of transfer material]
In general, gloss paper has a high smoothness, and thus has a property of easily causing dirt on the secondary transfer roller 22 as back dirt. As shown in FIG. 5 (a), the most effective means for avoiding the back dirt is to take a gap between the sheets of the gloss paper as compared with the plain paper. More specifically, a large space is taken between the supplied toner image and the real image of the next page. Here, FIG. 5A is a diagram showing a real image formed on the intermediate transfer belt 10 and a supplied toner image of the pattern A. FIGS. 5A and 5I are those in the case where image formation is performed on plain paper. FIGS. 5A and 5I show a case where image formation is performed on glossy paper. Specifically, the dirt on the secondary transfer roller 22 due to the supplied toner image is transferred to the intermediate transfer belt 10 by expanding the gap between the sheets by at least the peripheral length of the secondary transfer roller 22 compared to the case of plain paper. That is, the image forming engine 620 determines the interval between the real image and the real image based on the circumference of the secondary transfer roller 22. Thereby, the back stain | pollution | contamination to gloss paper can be suppressed.

[Toner supply timing chart]
FIGS. 5B and 5I are diagrams when image formation is performed on plain paper, and FIGS. 5B and 5I are diagrams when image formation is performed on glossy paper when the pattern A is used as the supply toner image. It is. FIGS. 5B and 5I are diagrams when an image is formed on glossy paper when the pattern C is adopted as the supplied toner image. More specifically, FIG. 5B and FIG. 5B show a supply toner image as a pattern A by the controller 650 as means for supplying toner to the intermediate transfer belt cleaning blade 27 when forming an image on glossy paper. Is the case. FIG. 5B and (iii) show a case where the image forming engine 620 itself creates a supply toner image as the pattern C.

ここで、Ｔ＿ｔｈは、予め時間を測定しておくことにより、既知の値として例えばＲＯＭ６０１等に保持しておく。その他の時間については実施例１と同様である。 First, the definition of each time described below is described in Table 2. The time not shown in Table 2 is the same as the definition in Table 1 of Example 1. N is the number of sheets on which gloss paper is formed as shown in Table 2.

Here, T_th is stored in the ROM 601 or the like as a known value by measuring the time in advance. Other times are the same as in the first embodiment.

  When the supply toner image is created as the pattern A by the controller 650, as described above, the backside of the gloss paper is suppressed by increasing the gap between the papers by an interval corresponding to the time T_th compared to the plain paper due to the properties of the gloss paper. doing. On the other hand, when the instruction of the controller 650 is determined to be glossy paper, the image forming engine 620 itself prepares the supplied toner image as the pattern C, whereby the toner is supplied to the intermediate transfer belt cleaning blade 27 in advance to obtain a lubricating effect. It is also possible. More specifically, as shown in FIG. 5B (iii), the supply toner image of the pattern C is formed in advance on the intermediate transfer belt 10 in the non-image area before the real image of one page (Page 1). Here, the amount of toner used for the supplied toner image of pattern C is equal to the total amount of toner used for the supplied toner image of pattern A when the same number of real images are formed. For example, in the case of FIG. 5B, the amount of toner used for the supplied toner image of pattern C is equal to the total amount of toner used for the supplied toner images of three patterns A. As described above, when the recording material is glossy paper, the image forming engine 620 can also form the supply toner image of the pattern C only in the region up to the start of image formation of the first page in the non-image region. . In this case, since the toner is supplied to the intermediate transfer belt cleaning blade 27 in advance, it is possible to form an image with at least the same productivity as plain paper. However, as described in the first embodiment, in the case of the pattern C, since the supplied toner image adheres to the secondary transfer roller 22, cleaning is performed by alternately applying a positive voltage and a negative voltage to the secondary transfer roller 22. It is necessary to carry out.

  Although it is possible for the controller 650 to prepare a supply toner image equivalent to the pattern C when the gloss paper is instructed, as described in the first embodiment, the sudden request from the image forming engine 620 I can't react immediately. As a result, unnecessary downtime due to waiting for the processing time of the controller 650 occurs.

Here, when image formation is performed on N sheets of glossy paper, the productivity (also referred to as the production rate) that is reduced when the controller 650 creates a supply toner image as the pattern A is expressed by (Expression 3).
T_th × (N−1) (Formula 3)
On the other hand, when image formation is performed on N sheets of glossy paper, productivity that decreases when a supply toner image is created as a pattern C by the image forming engine 620 is expressed by (Expression 4).
T_pat_C + T_cln (Expression 4)

  When the difference T_diff2 (= (Expression 3) − (Expression 4)) obtained by subtracting the time of (Expression 4) from the time of (Expression 3) is larger than 0, the image forming engine 620 supplies the supplied toner image of the pattern C. The rate of decrease in productivity of the image forming apparatus is reduced by forming. On the other hand, when the time difference T_diff <b> 2 is 0 or less, the productivity reduction rate is smaller when the controller 650 forms the supply toner image of the pattern A.

[Supply toner image selection process]
FIG. 6 is a flowchart for starting image formation when glossy paper is instructed from the controller 650. In step S200, the image forming engine 620 determines whether or not a glossy paper instruction is received from the controller 650. If it is determined that the glossy paper instruction is not received, the process of step S200 is repeated. If the image forming engine 620 determines in step S200 that the gloss paper instruction has not been received, the flowchart illustrated in FIG. 4 of the first embodiment may be executed.

  If the image forming engine 620 determines in step S200 that a gloss paper instruction has been received from the controller 650, in step S201, the image forming engine 620 calculates a time difference T_diff2 from (expression 3) and (expression 4). In step S202, the image forming engine 620 determines whether the time difference T_diff2 calculated in step S201 is greater than zero. If the image forming engine 620 determines in S202 that the time difference T_diff2 is greater than 0 (T_diff2> 0), the image forming engine 620 forms a supply toner image of pattern C in S203. The image forming engine 620 completes the formation of the supplied toner image of the pattern C on the intermediate transfer belt 10 and the supplied toner image passes through the secondary transfer nip portion. Apply voltage alternately. As a result, the secondary transfer roller 22 is cleaned.

  On the other hand, if the image forming engine 620 determines in step S202 that the time difference T_diff2 is 0 or less (T_diff2 ≦ 0), the supply toner image of the pattern A is generated by the controller 650, so that the entire process is not performed. Terminate the process. Thereafter, the flowchart described in FIG. 4 of the first embodiment may be executed.

  Note that after the image forming engine 620 determines that the gloss paper instruction has been received in S200, a supply toner image change request may be generated as in the first embodiment. In this case, the time required for image formation is determined for the supplied toner image pattern from (Equation 1) and (Equation 2) described in Embodiment 1 and (Equation 3) and (Equation 4) described in this embodiment. Alternatively, a pattern having a low productivity reduction rate may be selected. In the embodiment described above, the image forming apparatus configured to secondarily transfer the toner image (real image) on the intermediate transfer belt 10 to the recording material 30 has been described. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus configured to form a pattern of a supplied toner image in a non-image area on a conveyance belt that conveys a recording material.

  As described above, according to this embodiment, it is possible to maintain the lubricity between the carrier and the cleaning unit while suppressing the decrease in productivity.

  In the above embodiment, the image forming engine 620 and the controller 650 are provided independently and communicate with each other via the video interface 640. However, the image forming engine 620 and the controller 650 may be configured as a single control unit.

2 Photosensitive drum 3 Developer 10 Intermediate transfer belt 27 Intermediate transfer belt cleaning blade 30 Recording material 620 Image forming engine 650 Controller

Claims (10)

A photoreceptor on which an electrostatic latent image is formed;
Developing means for developing the electrostatic latent image formed on the photoreceptor with toner;
A carrier carrying a toner image or a recording material formed by the developing means;
Cleaning means for cleaning the carrier in contact with the carrier;
A controller that processes the input image information;
Control means for controlling the photoconductor, the developing means, and the carrier based on image information processed by the controller;
With
An image forming apparatus operable in a mode of supplying toner to the cleaning unit by forming a toner image on a non-image area of the carrier,
The control means forms a first toner image based on the image information processed by the controller when forming a toner image in the non-image area, or based on the image information processed by the controller , It is determined whether or not a second toner image different from the first toner image is to be formed, and a first time required to form the first toner image and a second toner image are formed. An image forming apparatus , wherein a toner image that requires a shorter one of the first time and the second time is selected . An irradiating means for irradiating the photosensitive member with a laser beam to form the electrostatic latent image;
Wherein, the second when you select a toner image, an image forming apparatus according to claim 1, characterized in that to irradiate the laser beam at a predetermined intensity by the irradiation means. Transfer means for transferring the toner image formed on the carrier to a recording material;
Application means capable of applying a positive voltage and a negative voltage to the transfer means;
With
The control means applies a positive voltage and a negative voltage to the transfer means by the application means to clean the transfer means after the second toner image formed on the carrier has passed through the transfer means. The image forming apparatus according to claim 2 , wherein the image forming apparatuses are alternately applied. The image forming apparatus according to claim 3 , wherein the second time includes a time during which a positive voltage and a negative voltage are alternately applied to the transfer unit by the applying unit. Wherein, when selecting the first toner image, depending on the type of the recording material, characterized in that to change the length of the moving direction of the carrier of the non-image area according to claim 3 or 5. The image forming apparatus according to 4 . Wherein, according to the case where the recording material is glossy paper, to claim 5, characterized in that lengthening the length of the moving direction of the non-image area as compared with the case where the recording material is plain paper Image forming apparatus. The image forming apparatus according to claim 6 , wherein the control unit determines a length of the non-image area in the moving direction based on a circumference of the transfer unit. Wherein the first time, the image forming apparatus according to any one of claims 5 to 7, characterized in that includes the time corresponding to the length of the moving direction of the non-image area. The control means selects the second toner image, and when the recording material is glossy paper, until the start of image formation of the toner image transferred to the recording material of the first page in the non-image area. only in the region, the image forming apparatus according to claim 3 or 4, wherein the forming the second toner image. It said second toner image is an image forming apparatus according to any one of claims 1 to 9, wherein the higher concentration than the first toner image.

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