JP7124691B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus used in electrophotographic printers, copiers, and the like.

2. Description of the Related Art Conventionally, there is an image forming apparatus that detachably holds a toner cartridge integrally configured with a storage section for storing toners (developers) of multiple colors, and replaces the toners of multiple colors together when the toner is replaced. rice field.
In addition, as a countermeasure against curling of a cleaning member of the transfer belt, there is a technique in which a patch pattern is transferred to the transfer belt (see, for example, Japanese Unexamined Patent Application Publication No. 2002-100001).

JP 2012-123164 A (page 5, FIG. 5)

However, when printing, the consumption of each toner is uneven, and when the toner cartridge is replaced, a large amount of toner of a color that cannot be completely consumed remains. was there.

An image forming apparatus according to the present invention includes:
A developing section for forming a developer image on a built-in electrostatic latent image carrier and a waste developer storage section for storing a waste developer image removed from the electrostatic latent image carrier are integrally formed, a plurality of developing units arranged along the rotational movement direction of the transfer belt ;
a plurality of transfer rollers arranged to face each of the electrostatic latent image bearing members of the plurality of developing units with the transfer belt interposed therebetween, and for transferring the developer image onto the transfer belt;
a developer cartridge integrally provided with a plurality of developer accommodating portions for supplying developers of different colors corresponding to the plurality of developing units;
a transfer control unit that monitors the amount of remaining developer in each of the plurality of developer storage units and the amount of use of the transfer belt, and controls transfer of the developer image;
The transfer control section transfers the developer image using the developer with the largest remaining amount of developer out of the respective amounts of remaining developer to the transfer belt, and the developer with the largest remaining amount of developer is transferred to the transfer belt. and when the amount is less than a predetermined amount, the developer is discarded by transferring the developer image using the developer accommodated on the most downstream side to the transfer belt in the rotational movement direction of the transfer belt. do.
Another image forming apparatus according to the present invention comprises:
an endless transfer belt;
a plurality of developing units for forming a developer image on an electrostatic latent image carrier;
a plurality of transfer rollers arranged to face each of the electrostatic latent image bearing members of the plurality of developing units with the transfer belt interposed therebetween, and for transferring the developer image onto the transfer belt;
a developer cartridge integrally provided with a plurality of developer accommodating portions for supplying developers of different colors corresponding to the plurality of developing units;
a transfer control unit that monitors the amount of developer remaining in each of the plurality of developer storage units and controls transfer of the developer image;
When the amount of the developer with the largest remaining amount of developer among the respective amounts of remaining developer is larger than a predetermined amount, the transfer control section performs the development using the developer with the largest remaining amount of developer. The developer image is transferred to the transfer belt, and if the amount is equal to or less than a predetermined amount, the developer image using the developer accommodated on the most downstream side in the rotational movement direction of the transfer belt is transferred to the transfer belt. It is characterized in that the developer is discarded.

According to the present invention, the plurality of developers contained in the developer cartridge are consumed substantially evenly, so that the above-described problems at the time of cartridge replacement can be resolved.

1 is a main configuration diagram showing a main configuration of an image forming apparatus 1 according to Embodiment 1 of the present invention; FIG. 2 is a configuration diagram of a transfer belt unit; FIG. FIG. 2 is a main configuration diagram showing the main configuration of an image forming unit together with an exposure device; 3 is a block diagram of a control system of the image forming apparatus; FIG. 2 is an external perspective view of a unit assembly that constitutes the image forming apparatus of the present embodiment; FIG. 2 is an external perspective view of a unit assembly main body and a toner cartridge with the toner cartridge removed; FIG. FIG. 3 is an external perspective view of the unit aggregate viewed from a position where a toner inlet formed in a slot thereof can be seen; FIG. 2 is an external perspective view of the toner cartridge as viewed obliquely from below; 3 is a perspective view showing the inside of the toner cartridge; FIG. 5 is a flow chart showing the flow of processing when toner disposal printing is executed by the image forming apparatus according to the first embodiment; 10 is a flow chart showing the flow of processing executed by the image forming apparatus according to the second embodiment when belt toner is discarded. FIG. 10 is a diagram for explaining the operation of the image forming apparatus according to the second embodiment;

Embodiment 1.
FIG. 1 is a main configuration diagram showing the main configuration of an image forming apparatus 1 according to Embodiment 1 of the present invention.

As shown in FIG. 1, the image forming apparatus 1 is configured as an electrophotographic printer, and has a substantially linear paper transport path having transport roller pairs 14 and 15, a feed roller pair 16, and a discharge roller pair 17. A roll paper 18 set in the roll paper setting section 11 is disposed at the most upstream end of the paper transport path, and a pair of discharge rollers for discharging the paper to the outside at the downstream end of the paper transport path. 17 are placed. A paper set sensor 36 for detecting that the roll paper 18 is set on the roll paper fixing shaft 19 is provided in the upstream portion of the paper transport path through which the roll paper 18 is fed.

The paper transport path includes transport roller pairs 14 and 15 for transporting the fed roll paper 18, a feed roller pair 16, and the feed roller pair 16 which causes the transported roll paper 18 to adhere to the transfer belt 43 by an electrostatic effect. A transfer belt unit 41 that conveys the toner image by means of a roller, and a fixing unit 55 that fixes the toner image on the roll paper 18 are provided.

Furthermore, a cutter unit 33 configured by the transport roller pair 15 and a cutter gear 33a and configured to cut the roll paper 18 is arranged downstream of the transport roller pair 14, and disposed downstream of the feed roller pair 16. A writing sensor 38 for detecting the leading edge of the paper 18 and outputting a detection signal that serves as an exposure trigger for an exposure device 27, which will be described later, is arranged. A discharge sensor 39 is arranged to detect discharge.

In this embodiment, the cutter unit 33 uses a rotary type cutter having a rotary blade that rotates in the paper running direction and a fixed blade that faces the rotary blade. Note that the roll paper 18 cut by the cutter unit 33 may be hereinafter referred to as recording paper 18 as a recording medium. The write sensor 38 includes an optical sensor 38b and a lever 38a, and is configured to change the state of light directed toward the optical sensor 38b to a light blocking state or a light transmitting state by rotating the lever with the recording paper 18. It is a photointerrupter.

FIG. 3 is a configuration diagram of the transfer belt unit 41, and the configuration of the transfer belt unit 41 will be described with reference to FIG.

The transfer belt unit 41 includes a transfer belt 43 made of a seamless endless plastic film, a drive roller 44 that is driven to rotate on the transfer belt 43 by a driving unit (not shown), and a pair of drive rollers 44 . A tension roller 45 on which the transfer belt 43 is stretched is disposed so as to face and press against photosensitive drums 25C, 25M, and 25Y (see FIG. 2) of image forming units 21C, 21M, and 21Y, which will be described later. Transfer rollers 42C, 42M and 42Y (referred to as transfer rollers 42 when there is no particular need to distinguish between them) for applying a voltage so as to transfer the toner images on the photosensitive drums 25C, 25M and 25Y to the recording paper 18; A transfer belt cleaning blade 35 as a scraping blade that scrapes and cleans the toner adhering to the belt 43, a contact roller 51 arranged to press against the transfer belt cleaning blade 35 with the transfer belt 43 therebetween, and a transfer belt cleaner. It includes a belt waste toner box 46 that stores toner scraped off by the blade 35 and a density sensor 50 that detects the image density on the transfer belt 43 .

Here, the movement of the transfer belt 43, which is stretched between the drive rollers 44 and moves in the direction of arrow G while rotating, may be referred to as rotational movement.

The belt waste toner box 46 includes a toner transport member 48 that transports collected toner into the container, a regulating member 47 that uniformly regulates the collected toner in the box, and a driving force that receives these members from the outside. A member 49 and the like are provided.

An image forming unit 21C that forms cyan (C) toner development sequentially from the upstream side in the conveying direction of the recording paper 18 at positions sandwiching the recording paper 18 that is conveyed while adhering to the transfer belt 43 by the transfer belt unit 41. , an image forming unit 21M for forming magenta (M) toner development, and an image forming unit 21Y for forming yellow (Y) toner development (referred to as image forming unit 21 when there is no particular need to distinguish between them). arrayed.

In the present embodiment, the image forming units 21C, 21M, and 21Y as these developing units are detachably arranged with respect to the main body of the image forming apparatus 1 and have the same configuration. Taking the image forming unit 21C as an example, the internal structure thereof will be described below. Incidentally, with respect to individual constituent elements of the image forming apparatus 1, such as the image forming unit 21 of the image forming apparatus 1, a portion excluding the constituent elements may be referred to as an image forming apparatus 1 main body.

FIG. 2 is a schematic diagram showing the main configuration of the image forming unit 21C together with the exposure device 27. As shown in FIG. Here, when there is no particular need to distinguish between different colors of toner used for each component, suffixes (C), (M), and (Y) are used to distinguish between them. may not be attached.

As shown in the figure, the image forming unit 21C is composed of a developing section 22 and an ID waste toner containing section 24 as a waste developer containing section, which are integrally constructed. 25, a charging roller 26 that uniformly charges the surface of the photosensitive drum 25, a developing roller 28 that forms a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 25, a developing blade 29, A supply roller 30 is provided in pressure contact with the developing roller 28, and further has a cleaning blade 32a, a waste toner receiving portion 32b, a conveying spiral 32c for conveying waste toner to the ID waste toner containing portion 24, and a final toner containing portion 31C. .

The photosensitive drum 25 as an electrostatic latent image carrier for carrying an electrostatic latent image forms an electrostatic latent image on its surface, and is driven by a belt motor 56 (FIG. 4) as will be described later. Rotate in the direction of arrow C. A predetermined voltage is applied to the charging roller 26 under the control of the charging voltage control section 125 (FIG. 4) to uniformly charge the surface of the photosensitive drum 25 .

An exposure device 27 is arranged above the photoreceptor drum 25 at a position facing the photoreceptor drum 25 . As shown in FIG. 1, the exposure device 27 is arranged corresponding to each of the three image forming units 21, and exposes each of the photosensitive drums 25 individually according to the image data of the corresponding color to generate an electrostatic latent image on the surface thereof. form an image.

The supply roller 30 is a roller that supplies the toner stored in the final toner storage portion 31C to the developing roller 28 . A developing blade 29 placed in pressure contact with the developing roller 28 thins the toner supplied from the supply roller 30 on the developing roller 28 . The toner used as a developer here is composed of a polyester resin, a colorant, a charge control agent, and a release agent, and is added with an external additive (hydrophobic silica). It is pulverized and has an average particle size of 7 μm.

The developing roller 28 develops the electrostatic latent image formed on the photosensitive drum 25 with toner, and is constructed by attaching an elastic member to the outer periphery of a metal shaft. For example, the developing roller 28 is configured by using a semi-conductive urethane rubber having a rubber hardness of 70° (Asker C) as an elastic body on a metal shaft.

The cleaning blade 32a, which is pressed against the surface of the photoreceptor drum 25, removes toner (residual toner) remaining on the photoreceptor drum 25 after transfer, which will be described later, or deteriorated inside the unit and forcibly adheres to the surface of the photoreceptor drum 25. The scraped toner is scraped off and dropped into the waste toner receiving portion 32b.

The ID waste toner storage unit 24 collects and stores the waste toner that has been scraped from the photosensitive drum 25 by the cleaning blade 32a and dropped into the waste toner receiving unit 32b via the transport spiral 32c or transport means (not shown). It is a place to put. The ID waste toner storage section 24 forms an image forming unit 21 integrally with the developing section 22. When the ID waste toner storage section 24 is full, the image forming unit 21 reaches the end of its service life and the photosensitive member When other components such as the drum 25 reach the end of their service life, replacement is encouraged even if the ID waste toner container 24 is not full.

Each transfer roller 42 of the transfer belt unit 41 is arranged in pressure contact with the corresponding photosensitive drum 25 via the transfer belt 43, and charges the recording paper 18 to the opposite polarity of the toner at this nip portion, thereby The toner image formed on the photosensitive drum 25 is transferred to the recording paper 18 .

The fixing unit 55 heats and melts the toner on the recording paper 18 to which the toner image has been transferred, which is conveyed between the heat roller 55a and the pressure roller 55b along the paper conveying path, thereby fixing the toner onto the recording paper. Fix the image. A discharge sensor 39 monitors a jam in the fixing section 55 or the winding of the recording paper 18 around a heat roller or the like. is discharged from the device.

The ejection sensor 39 includes an optical sensor 39b and a lever 39a in the same manner as the write sensor 38. By rotating the lever 39a of the recording paper 18, the light directed to the optical sensor 39b is blocked or transmitted. is a photointerrupter configured to change to The image forming apparatus 1 also has an operation panel 57 on its outer casing.

In FIG. 1, each of the X, Y, and Z axes takes the X axis in the transport direction when the roll paper 18 passes through each image forming unit 21, and the Y axis in the rotation axis direction of each photosensitive drum 25. , and the Z-axis is taken in a direction orthogonal to these two axes. Also, when the X, Y, and Z axes are shown in other drawings to be described later, these axial directions indicate the common direction. That is, the X-, Y-, and Z-axes in each figure indicate the arrangement directions when the parts depicted in each figure constitute the image forming apparatus 1 shown in FIG. Also, here, it is assumed that the Z-axis is arranged in a substantially vertical direction.

FIG. 4 is a block diagram of the control system of the image forming apparatus 1. As shown in FIG.

As shown in the figure, the image forming apparatus 1 includes a control unit 101 including a print control unit 101a and a toner disposal control unit 101b, an interface control unit 103, an operation input unit 113, a ROM (Read Only Memory) 105a and a RAM ( Random Access Memory) 105b, a CPU (Central Processing Unit) 111, various sensors 112, a process control section 121, a development voltage control section 122 for controlling the voltage applied to the development roller 28, and the voltage applied to the supply roller 30. , a layer formation voltage control unit 124 that controls the voltage applied to the developing blade 29, a charging voltage control unit 125 that controls the voltage applied to the charging roller 26, and a voltage applied to the transfer roller 42. A transfer voltage control unit 126 that controls, an exposure control unit 128 that controls the exposure devices 27 (27C, 27M, and 27Y), and a motor control unit 127 that controls the rotation of the belt motor 56 that drives the drive roller 44 and the photosensitive drum 25. is composed of

The interface control unit 103 receives print data and control instructions (control commands) from the higher-level device 102 as information input means. The printing operation of the image forming apparatus 1 is controlled based on. The operation input unit 113 is an operation panel 57 or the like provided with input means such as operation buttons for receiving input operations by an operator and display means such as a display.

The memory 105 is a storage unit composed of a ROM 105a and a RAM 105b. The ROM 105a stores a control program (software) and control data for controlling and processing the overall operation of the image forming apparatus 1, and the RAM 105b stores the control program. It temporarily stores various information generated by the execution of Here, it is assumed that a rewritable flash ROM or the like is used as the ROM 105a.

A CPU 111 as a main control unit controls and processes the overall operation of the image forming apparatus 1 based on a control program stored in the ROM 105 a of the memory 105 . The various sensors 112 are sensors that detect the recording paper 18, including the writing sensor 38 shown in FIG. The density sensor 50 is arranged along the running position of the transfer belt 43 as shown in FIG. 1 and detects the image density on the transfer belt 43 .

The development voltage control unit 122 controls the voltage (development voltage) applied to the development roller 28, the supply voltage control unit 123 controls the voltage (supply voltage) applied to the supply roller 30, and the layer formation voltage control unit 124 controls the , the voltage applied to the developing blade 29, the charging voltage control unit 125 controls the voltage (charging voltage) applied to the charging roller 26, and the transfer voltage control unit 126 controls the transfer roller 42 (42C, 42M, 42Y ) is controlled (transfer voltage).

The exposure control unit 128 controls the exposure of the exposure devices 27 (27C, 27M, 27Y) according to the print data, and the motor control unit 127 drives the transfer belt 43 to rotate in the direction of arrow G (FIG. 3). The roller 44 is rotationally driven, and the rotation of the belt motor 56 that rotationally drives the photosensitive drum 25 in the direction of arrow C (FIG. 2) is controlled. At one end of the photosensitive drum 25 , the developing roller 28 , and the supply roller 30 , gears for transmitting driving force are provided, and the gears of the developing roller 28 and the supply roller 30 mesh with the gear of the photosensitive drum 25 . As a result, the developing roller 28 and the supply roller 30 rotate in predetermined directions at predetermined rotational speeds as the photosensitive drum 25 rotates.

The interface control unit 103, the operation input unit 113, the memory 105, the CPU 111, and the various sensors 112 are connected to the print control unit 101a and output signals to the print control unit 101a. The unit 122, the supply voltage control unit 123, the layer formation voltage control unit 124, the charging voltage control unit 125, the transfer voltage control unit 126, and the motor control unit 127 are connected to the print control unit 101a, and output from the print control unit 101a. Operate by receiving a signal. Note that the control unit 101, the memory 105, and the CPU 111 correspond to the transfer control unit.

5 is an external perspective view of the unit assembly 2 constituting the image forming apparatus of the present embodiment, and FIG. 6 is an external perspective view of the main unit assembly 2 and the toner cartridge 4 with the toner cartridge 4 removed. It is a diagram.

As shown in these figures, the unit assembly 2 is integrally constructed by mounting three image forming units 21C, 21M, and 21Y on the basket frame 6, respectively. A toner cartridge 4 as a developer cartridge is detachably attached to the slot 3 provided. 5 shows the toner cartridge 4 installed in the slot 3, and FIG. 6 shows the toner cartridge 4 pulled out from the slot 3. As shown in FIG.

This unit assembly 2 is arranged in the main body of the image forming apparatus 1 so that, as shown in FIG. , and the rotational driving force of each rotating portion is obtained from the main body side of the image forming apparatus 1 .

FIG. 7 is an external perspective view of the unit assembly 2 as seen from the position where the toner inlets 62C, 62M, and 62Y formed in the slot 3 can be seen, and FIG. 8 is an external perspective view of the toner cartridge 4 as seen obliquely from below. FIG. 9 is a perspective view showing the inside of the toner cartridge 4. As shown in FIG. Therefore, in FIG. 9, the outer wall of the toner cartridge 4 is partially removed so that the inside can be seen.

As shown in FIG. 5, when the three image forming units 21C, 21M and 21Y are attached to the basket frame 6 and assembled integrally with the slot 3, the three image forming units 21C, 21M and 21Y are, for example, As shown in FIG. 1, the slots 3 are arranged in a line in a predetermined direction at predetermined intervals. etc. are arranged to connect with each other.
In some cases, the front (front side), rear (back side), left and right sides of the unit aggregate 2 are specified when viewed from the roll paper discharge side (direction of arrow A).

That is, the slot 3 is arranged so that the longitudinal direction (X-axis direction), which is the insertion/removal direction of the toner cartridge 4 described later, is aligned with the arrangement direction of the three image forming units 21C, 21M, and 21Y. A toner inlet 62C formed in the portion 61 overlaps an opening (not shown) formed in the slot mounting portion of the image forming unit 21C, and enters the final toner containing portion 31C (FIG. 1) of the image forming unit 21Y. Similarly, the toner inlet 62M overlaps with an opening (not shown) formed in the slot mounting portion of the image forming unit 21M and communicates with the final toner containing portion 31M (FIG. 1) of the image forming unit 21M. The toner inlet 62Y is configured to overlap an opening (not shown) formed in the slot mounting portion of the image forming unit 21C and communicate with the final toner storage portion 31Y (FIG. 1) of the image forming unit 21C. there is

As shown in FIGS. 8 and 9, the toner cartridge 4 has a substantially rectangular parallelepiped outer shape, and the inside of the toner cartridge 4 is a toner containing portion for containing cyan (C) toner, which is separated by partition walls 82 and 83 (FIG. 9). 84C, an in-cartridge toner storage unit 84M that stores magenta (M) toner, and an in-cartridge toner storage unit 84Y that stores yellow (Y) toner. ) are divided into three in-cartridge toner containing portions 84 as developer containing portions.

At the front end of the toner cartridge 4, a handle 80 is formed which serves as a handle for inserting and removing from the slot 3 (FIG. 3). Three toner outlets 91C, 91M and 91Y are formed at the bottoms of the toner containing portions 84C, 84M and 84Y.

These toner outlets 91C, 91M and 91Y can be opened and closed by an opening/closing shutter 95 (FIG. 8) slidably held on the bottom portion 90. As shown in FIG. The opening/closing shutter 95 is a plate-like member having three openings 95a, 95b, and 95c, and extends in the longitudinal direction of the toner cartridge 4 (the direction in which the three in-cartridge toner storage portions 84 are adjacent to each other). It is held by the holding member so as to be slidable in the same direction.

The opening/closing shutter 95 is urged in the direction of arrow A, which is the insertion direction of the toner cartridge 4, by an urging means (not shown), and closes the toner outlets 91C, 91M, 91Y of the toner cartridge 4 when it is not acted upon by others. When the toner cartridge 4 is installed in the slot 3, the openings 95a, 95b, and 95c of the open/close shutter 95 are slid along with the installation, and the toner outlets 91C, 91M, and 91C of the toner cartridge 4, respectively. Overlapping with 91Y, each toner outlet is opened to be in an open state.

Further, as shown in FIG. 9, the toner cartridge 4 is provided with a stirring shaft 97 that extends in the longitudinal direction through the three in-cartridge toner containing portions 84C, 84M, 84Y and is rotatably held. . The agitating shaft 97 has a passive gear 99 at its tip in the insertion direction (direction of arrow A), and when the toner cartridge 4 is installed in the slot 3, a drive gear (not shown) arranged on the side of the slot 3 ) and rotate by receiving the driving force.

As described above, in the image forming apparatus 1, the three image forming units 21 supply toner of corresponding colors from the toner cartridge 4 integrally formed with the three in-cartridge toner accommodating portions 84C, 84M, and 84Y. Since the toner cartridge 4 is supplied, the toner cartridge 4 is replaced with a new toner cartridge 4 when any of the in-cartridge toner accommodating portions 84 of the toner cartridge 4 becomes empty. Therefore, if there is variation in the amount of toner consumed, the cartridge must be replaced with unused toner remaining in the storage portion of the toner storage portion 84 in the cartridge.

Next, a toner disposal method for preventing the transfer belt cleaning blade 35 from being turned over (hereinafter, sometimes simply referred to as a countermeasure against turning over) will be described. The toner disposal printing method for countermeasures against curling consists of an image forming process for performing normal printing on the recording paper 18 and a toner disposal process for countermeasures against curling.

Here, first, terms to be used from now on will be explained.
Belt count value Cb: A numerical value for counting the amount of use of the transfer belt 43, and the number of rotations of the photoreceptor drum 25, with the moving amount of the transfer distance (463.74 mm) corresponding to one rotation of the photoreceptor drum 25 being counted as one count. corresponds to
Toner consumption count value Ds: A numerical value for counting the amount of toner consumption. The print control unit 101a counts the number of print dots of each color based on the print data, and counts the amount of toner used per unit amount, and is proportional to the amount of toner consumption. represents a number. The toner consumption count value Ds is reset when the toner cartridge 4 is replaced.
Belt waste toner count value Th: A numerical value for counting the amount of waste toner stored in the belt waste toner box 46 of the transfer belt unit 41, and is a numerical value proportional to the amount of waste toner calculated by the print control unit 101a.
Toner fill count value Ds_life: indicates a value obtained by converting the amount of unused toner filled in each in-cartridge toner containing portion 84 (FIG. 9) of the toner cartridge 4 into the toner consumption count value Ds.

The toner discard control unit 101b discards toner as a developer according to the belt count value Cb as the usage amount of the transfer belt, the toner consumption count value Ds detected by the print control unit 101a, and the belt waste toner count value Th. It is equipped with a function for discarding toner. This toner disposal will be described later in detail with reference to the flow chart of FIG.

When the printing operation starts, the print control unit 101a calculates the toner fill count value Ds_life corresponding to the amount of toner filled in the toner storage unit 84 in each cartridge 4 recorded in the ROM 105a and RAM 105b, and actual printing. It has an arithmetic processing function for calculating a toner remaining amount count value Ds_rest as a developer remaining amount corresponding to the toner remaining amount from the toner consumption count value Ds corresponding to the used toner consumption amount.

The control unit 101 including the toner disposal control unit 101b and the print control unit 101a executes operation instructions to each control unit based on the belt waste toner count value Th or the belt count value Cb. That is, the control unit 101 determines whether to execute a printing operation or a toner disposal operation, and controls a motor control unit 127, an exposure control unit 128, and voltage control units 122 to 126 according to each operation. Upon receiving an instruction from the control unit 101, the motor control unit 127 controls the rotation of the drive roller 44 that drives the transfer belt 43 and the belt motor 56 that rotationally drives the photosensitive drum 25 via transmission means (not shown).

Upon receiving an instruction from the control unit 101, the exposure control unit 128 controls the light emission of the exposure device 27. Upon receiving an instruction from the control unit 101, each of the voltage control units 122 to 126 controls the corresponding developing roller 28, Applied voltages applied to the supply roller 30, the developing blade 29, the charging roller 26, and the transfer roller 42 are controlled.

On the other hand, when the control unit 101 confirms that one of the belt waste toner count value Th and the belt count value Cb has reached the threshold value that determines the life, it stops the printing operation, and the transfer belt unit 41 reaches the end of its life. is displayed on the operation panel 57 of the image forming apparatus 1 belonging to the operation input unit 113 .

In the image forming apparatus 1 of the present embodiment, the transfer belt cleaning blade 35 removes the toner of the color with the largest toner remaining amount count value Ds_rest corresponding to the remaining toner amount in the three in-cartridge toner storage units 84 of the toner cartridge 4 . Toner was discarded as a countermeasure against curling, and the more suitable timing (frequency) of discarding was determined by the first and second printing tests described later.

FIG. 10 is a flow chart showing the flow of processing performed by the image forming apparatus 1 according to the present embodiment when toner disposal printing is performed. The operation during toner disposal printing will be described below with reference to the flowchart.

This processing starts when the image forming apparatus 1 starts printing.
A≦Cb(Th)−Cb(La) (1)
Then, it is determined whether or not the current belt count value Cb(Th) has increased from the belt count value Cb(La) when the toner was discarded last time to the threshold value A (step S101). By selecting the threshold value A, the interval (frequency) of toner disposal can be adjusted. Until the belt count value Cb reaches A, the image forming apparatus 1 performs normal printing.

When the toner disposal control unit 101b determines that the timing for toner disposal has come (step S101, Yes), the print control unit 101a checks the toner fill count value Ds_life of each color (C, M, Y). (Step S102), furthermore, the toner consumption count value Ds corresponding to the toner consumption of each color (C, M, Y) actually used in printing is confirmed (Step S103), and the following equation (2) is obtained.
Ds_rest(*)=Ds_life(*)-Ds(*) (2)
to calculate the toner remaining amount count value Ds_rest for each color (C, M, Y). Toner with a large number of .DELTA. is determined (step S104).

Note that Ds_rest(*) is set to *=C, M, Y, so that the toner remaining amount count value Ds_rest(Y) for yellow (Y), the toner remaining amount count value Ds_rest(M) for magenta (M), Indicates the remaining toner count value Ds_rest(C) for cyan (C). The same applies to Ds_life(*) and Ds(*).

In this step S104, for example, when the toner remaining amount count value Ds_rest indicates the maximum value (same value) for a plurality of toners, the image forming unit arranged downstream in the medium conveying direction (arrow D direction) shown in FIG. 21 is preferentially selected.

This is because, as shown in FIGS. 5 to 9, when the toner cartridge 4 is pulled out from the slot 3, toner outlets 91 (toner outlets) of the toner containing portion 84 in the cartridge on the downstream side receive toner of other toners. Pass 62. For example, the cyan (C) toner outlet 91C passes through the magenta (M) toner inlet 62M and the yellow (Y) toner inlet 62Y. If there is a large amount of cyan (C) toner remaining, the cyan (C) toner will be mixed in the magenta (M) and yellow (Y) toner inlets 62 due to toner leakage or the like. This is because it is desired to reduce the toner on the downstream side first.

The toner discard control unit 101b sets the transfer voltage to the transfer voltage for printing (step S105), and uses the toner with the largest remaining amount determined in step S104 to discard the toner onto the transfer belt 43. (Step S106), and then normal print processing is executed (Step S107).

Here, toner disposal as a countermeasure against curling performed in step S106 will be described. Here, the exposure amount of the selected toner in the entire printable area in the main scanning direction (Y-axis direction) of the transfer belt 43 and the predetermined length range in the sub-scanning direction (X-axis direction) A 50% harptone pattern toner development is transferred directly to the transfer belt 43 . As a result, the contact resistance between the transfer belt 43 and the transfer belt cleaning blade 35 is reduced, and the curling phenomenon of the transfer belt cleaning blade 35 can be reduced.

Here, the length in the sub-scanning direction is 5 cm when the apparatus is started, and 2 cm when printing is finished. Since the toner disposal is accompanied by the rotation of the photosensitive drum 25, it is preferable to execute it in accordance with other operations accompanied by the rotation of the photosensitive drum 25 as a countermeasure for the life of the photosensitive drum.

Next, according to the flow of FIG. 10 described above, when executing toner disposal printing accompanied by toner disposal, various threshold values A in the above equation (1) performed in step S101 are set, 55%, hereinafter referred to as NN environment), first and second printing tests for determining a suitable threshold value A will be described.

In the first printing test, a printed material that is actually used by a user for printing, that is, the duty is biased for each color, is used, and the threshold value A in the above equation (1) performed in step S101 is changed (A=100, 160 , 350 and 500), the toner disposal printing was executed until the amount of toner in the toner containing section 84 in the cartridge reached the level at which the toner of a certain color became unprintable.

When a series of toner disposal printing is completed, the amount of toner M1 (*) [g] (*: C, M, Y) of each color remaining in the toner containing portion 84 in the cartridge is measured, and the following equation (3) is obtained.
M2[g]=(M1(Y)+M1(M)+M1(C))/3[g] (3)
The average amount M2 [g] was calculated by

Furthermore, using the toner amount M1 (*) [g] (* is C, M, Y) of each color and the average amount M2 [g], the following equation (4) is obtained.
R (*) [%] = (M1 (*) - M2) / M2 [%] (*: C, M, Y) (4)
Table 1 shows test results (1) in which the amount of bias R (*) [%] (*: C, M, Y) for each color was calculated by

In the second printing test, under the same conditions as in the first printing test, printing was performed until the amount of toner in the toner storage unit 84 in the cartridge was such that the toner of a certain color could not be printed. Using the remaining toner amount M1 (*) [g] (*: C, M, Y), the following equation (5)
M3 (*) [g] = M1 (*) [g] - 3 [g] (5)
Table 1 shows the test result (2) of calculating the toner amount M3 (*) [g] (*: C, M, Y) remaining in the vicinity of the toner outlet 91 (FIG. 9) as a toner supply port.

Note that 3 [g] in the above equation (5) is the estimated total weight of the toner adhering to the inner wall of the toner containing portion 84 in the cartridge and the film material of the stirring shaft 97 provided inside.

Furthermore, in this second printing test, as test result (2), the result of visually confirming whether or not toner drop occurred when the toner cartridge 4 was inserted into and removed from the slot 3 (see FIG. 6) at the same time was confirmed. It is written together.

Next, evaluation criteria for evaluating the first and second test results will be described.

First, in the first test result (1), the bias amount R (*) [%] (*: C, M, Y) for each color is
-10% ≤ R (*) [%] ≤ +10%
If it is judged as good (○),
R (*) [%] <-10% or +10% < R (*) [%]
Table 1 shows evaluation (1), which is the judgment result.

This reference value Rref=10 (%) is such that when the amount of toner in the cartridge toner containing section 84 becomes such that the toner of a certain color cannot be printed, the toner cartridge 4 is shaken and the movement of the toner is felt. It is a calculated value as the remaining amount of the boundary between when you feel it and when you don't feel it.

Next, in the second test result (2), the toner amount M3 (*) [g] (*: C, M, Y) remaining in the vicinity of the toner supply port is the reference value Mref = 1.5 [g]. in the comparison of
M3 (*) [g] ≤ Mref (%) = 1.5 [g]
If it is judged as good (○),
Mref (%) = 1.5 [g] < M3 (*) [g]
Table 1 shows evaluation (2), which is the judgment result.

Furthermore, in this second test result, the degree of toner drop when the toner cartridge 4 is inserted into or removed from the slot 3 (see FIG. 6) is confirmed.
If the toner does not drop from the toner outlet 91 (FIG. 9) serving as a supply port and does not stain the apparatus, it is judged to be good (◯).
If the toner falls from the supply port and the toner stains on the device, it is determined to be defective (x).
Table 1 shows evaluation (3), which is the determination result.

In Comparative Example 1, as a comparative example, toner of a specific color, for example, toner of the last color to be transferred to the medium (hereinafter sometimes referred to as the most downstream toner) is used for the toner disposal onto the transfer belt. In the case of using toner amount M1 (*) [g] (*: C, M, Y), average amount M2 [g], and deviation amount R (*) [%] (*: C, M , Y) were calculated and similarly compared with the reference value Rref=10[%].

As a comprehensive judgment, if all evaluations are good (○), it is judged to be comprehensively effective (◎), and if there is even one item that is defective (×), there is no overall effect (× ).

As described above, from the results of the first and second printing tests, in the image forming apparatus using the toner cartridge 4 containing toner of a plurality of colors, the image forming apparatus 1 of the present embodiment has a countermeasure against curling of the belt cleaning blade. When the toner is discarded, among the toners contained in the plurality of in-cartridge toner containing portions 84, the toner with the largest remaining amount is used, and the frequency of toner disposal is adjusted. By setting the threshold value A to 100 or 160, unevenness in the remaining amount of toner is prevented.

At the same time, printing is performed until the amount of toner in the cartridge toner containing portion 84 becomes such that the toner of a certain color becomes unprintable. The amount of toner in the vicinity of the toner supply port is suppressed to 1.5 [g] or less. As a result, when the toner cartridge 4 is replaced, it is possible to prevent the toner from dropping from the supply port and causing toner stains on the apparatus.

From the test results, increasing the frequency of toner disposal (lowering the threshold value A) has the effect of preventing unevenness in the remaining amount of toner due to the above-described action. 21, it is preferable to set the minimum frequency (here, A=160) within the range where the effect can be expected.

In the present embodiment, the remaining amount of each toner in the toner cartridge 4 is expressed as a count value based on print data, but the present invention is not limited to this, and the remaining amount of each toner in the toner cartridge 4 is directly sensed. Various aspects can be taken, such as providing a sensor for detection.

As described above, according to the image forming apparatus of the present embodiment, as a countermeasure for preventing the belt cleaning blade from turning over, even when toner is discarded, unevenness in the remaining amount of toner is prevented. In addition, it is possible to prevent the toner cartridge from being wastefully replaced with a large amount of toner remaining, and to prevent the remaining toner from staining the toner cartridge when the toner cartridge is replaced.

(Modification 1)
In this modification, at step S104 in the flowchart of FIG. 10, at the stage where the toner with the largest remaining amount is determined based on the three-color toner remaining amount count Ds_rest(*) (*: C, M, Y), If the determined remaining amount of toner has already decreased to the extent that there is no risk of toner falling off, instead of the toner determined in step S104, the toner is placed downstream in the medium transport direction (direction of arrow D) shown in FIG. The toner corresponding to the selected image forming unit 21 is preferentially selected.

Incidentally, when it is determined that the amount of toner has decreased to the extent that there is no risk of toner falling off, for example, from the test result (2) shown in Table 1, the remaining amount of toner can be determined to be 4.5 g or less.

This is because, as shown in FIGS. 5 to 9, when the toner cartridge 4 is pulled out from the slot 3, toner outlets 91 (toner outlets) of the toner containing portion 84 in the cartridge on the downstream side receive toner of other toners. Pass 62. For example, the most downstream cyan (C) toner outlet 91C passes through the magenta (M) toner inlet 62M and the yellow (Y) toner inlet 62Y. If there is a large amount of cyan (C) toner remaining, it is possible to prevent the cyan (C) toner from being mixed in the magenta (M) and yellow (Y) toner inlets 62 due to toner leakage or the like. This is because it is desirable to first empty the toner on the downstream side in order to reliably prevent this.

Embodiment 2.
FIG. 11 is a flow chart showing the flow of processing executed by the image forming apparatus according to the second embodiment when belt toner is discarded, and FIG. 12 is a diagram for explaining the operation of the image forming apparatus according to the present embodiment. .

The main difference between the image forming apparatus of the second embodiment and the image forming apparatus of the first embodiment that executes the flow chart shown in FIG. 10 is the control method of the transfer voltage when the toner is discarded. Accordingly, portions of the image forming apparatus of the present embodiment that are common to the image forming apparatus 1 of the first embodiment are denoted by the same reference numerals, or the drawings are omitted to omit the description, and the points of difference are emphasized. explained in detail. Except for the points described above, the main configuration of the image forming apparatus of the present embodiment is the main configuration of the image forming apparatus 1 of the first embodiment shown in FIG. 1 and the block diagram of the control system shown in FIG. 1 and 4 are referred to as necessary.

In the first embodiment, when the toner is discarded as a countermeasure against curling of the belt cleaning blade, the toner with the largest remaining amount among the toners contained in the plurality of in-cartridge toner containing portions 84 is used and the toner is discarded. The configuration, action, and effect for preventing unevenness in the remaining amount of toner by adjusting the frequency of toner disposal have been described.

However, if the toner to be discarded belongs to the image forming unit 21 positioned upstream in the paper transport direction (the direction of arrow G shown in FIG. 1), the toner is reversed in the image forming unit 21 positioned downstream. There is a possibility that the ID waste toner storage section 24 provided in the image forming unit 21 may be filled early.

The term "reverse transfer" as used herein means that the toner discarded on the transfer belt 43 in the image forming unit 21 on the upstream side is transferred to the nip between the photosensitive drum 25 provided in the image forming unit 21 on the downstream side and the transfer roller 42 facing the photosensitive drum 25. This is a phenomenon of moving backward to the photosensitive drum 25 side when passing through a part.

Normally, the toner on the photoreceptor drum 25 is negatively charged. Therefore, applying a positive voltage to the transfer roller 42 causes the toner to move to the transfer belt 43 side. However, since some toner is positively charged (or negatively charged) due to a slight discharge phenomenon that occurs when it moves to the transfer belt 43, the photosensitive drum 25 provided in the image forming unit 21 on the downstream side and the When passing through the nip portion with the transfer roller 42 facing the transfer roller 42 , a phenomenon occurs in which the transfer roller 42 repels the positive voltage and moves toward the photosensitive drum 25 .

The image forming apparatus of the present embodiment solves the above problem, and a method for dealing with the problem will be described with reference to the flowchart of FIG.

Processing steps S201 to S206 of this flow correspond respectively to processing steps S101 to S106 of the flow shown in FIG. be.

That is, in steps S201 to S204, the belt count value Cb is checked, and when the toner disposal timing arrives, the toner with the largest remaining amount among the toner stored in the toner storage section 84 in the cartridge is determined.

When the toner disposal control unit 101b determines the toner to be used for toner disposal in step S204, in the present embodiment, in step S205, the control unit 101 instructs the transfer voltage control unit 126 to select the color of the toner to be used for toner disposal. A transfer voltage for printing is applied to the corresponding transfer roller 42, and an instruction is given to the other transfer rollers 42 to set the applied voltage to 0V. A voltage is applied to the transfer roller 42 .

In this state, the toner disposal control unit 101b executes toner disposal onto the transfer belt 43 (step S206), and then executes normal printing processing (step S207).

Here, a specific operation example will be described with reference to FIG. In the figure, the direction of arrow G indicates the transport direction of the recording paper 18 transported by the transfer belt 43 . When the toner disposal control unit 203 determines in step S204 that the toner to be used for toner disposal is, for example, magenta (M) toner, the nip portion is opposed to the photosensitive drum 25M of the magenta ( M ) image forming unit 21. A transfer voltage during printing is applied to the transfer roller 42M to be formed, and at the same time, the transfer roller 42Y forms a nip portion facing the photosensitive drum 25Y on the downstream side and the photosensitive drum 25C on the upstream side. 0 V is applied to the transfer roller 42C.

Next, according to the flow shown in FIG. 11, when executing printing accompanied by toner disposal, under variously set test environments, the developer used for toner disposal is transferred to another image forming unit 21 by reverse transfer. A reverse transfer confirmation test performed to confirm how much waste toner is stored in the ID waste toner storage unit 24 will be described. For the determination in step S201, the threshold value A was set to 160 counts, which gave good results in the test conducted in the first embodiment.

In the test, we used printed material that is actually used by users in printing, that is, the duty is biased for each color, and changed the test environment (NN environment, high temperature and high humidity, low temperature and low humidity), and Toner disposal printing was performed until the amount of toner in the cartridge toner storage unit 84 reached the point at which printing became impossible.

When a series of toner disposal printing is completed, the amount of toner accommodated in the ID waste toner storage section 24 of the other image forming unit 21 by reverse transfer at the time of toner disposal (hereinafter sometimes referred to as reverse transfer toner amount) ) S1(*) [g] (*: C, M, Y) and the amount of toner S2 (*) [g] (*: C, M, Y) and the following formula (6)
S(*) [%]={45-(S1(*)+S2(*))}/45 (6)
, the amount of toner that can be additionally stored in the ID waste toner storage unit 24 (hereinafter sometimes referred to as additional allowable toner amount) S(*) [%] was calculated. Table 2 shows the calculation results. 45 [g] is the maximum weight of the toner that can be filled in the ID waste toner container 24 .

In Table 2,
Test result (1) shows the result of a reverse transcription confirmation test in a temperature and humidity environment (temperature 22 ° C., humidity 55%: NN environment),
Test result (2) shows the results of a reverse transfer confirmation test in a temperature and humidity environment (temperature 27° C., humidity 80%: high temperature and high humidity).
Test result (3) shows the results of a reverse transcription confirmation test in a temperature and humidity environment (temperature 10° C., humidity 20%: low temperature and low humidity).

In Table 2, the test result of the reverse transfer toner amount S1 [g] shown in the column (M) of the item "developer discarded toner" shows that the magenta (M) toner discarded when the toner is discarded is , indicates the amount accommodated in each ID waste toner accommodating portion 24 by reverse transfer. Therefore, since reverse transfer is not performed to the magenta (M) ID waste toner storage unit 24M and the cyan (C) ID waste toner storage unit 24C on the upstream side of magenta (M), the reverse transfer toner amounts S1(M), S1 (C) is zero.

In addition, the test result of the reverse transfer toner amount S1 [g] shown in the column (C) of the item "Developer Discarded Toner" shows that the cyan (C) toner discarded at the time of toner disposal is reversed. It shows the amount stored in each ID waste toner storage unit 24 by copying. Therefore, the reverse-transferred cyan (C) toner is stored in the magenta (M) ID waste toner storage unit 24M and the yellow (Y) ID waste toner storage unit 24Y located downstream of cyan (C). The reverse transfer toner amount S1(C) is zero only in the cyan (C) ID waste toner container 24C that is not reverse transferred.

Furthermore, if the yellow (Y) toner located at the most downstream position is discarded when the toner is discarded, reverse transfer does not occur, so the yellow (Y) toner is not evaluated.

The test results of Comparative Example 2 shown in Table 2 were obtained by applying the transfer voltage during printing to all the transfer rollers 42 when the toner was discarded (corresponding to the case of Embodiment 1). It shows test results.

Next, evaluation criteria for evaluating the test results in the reverse transcription confirmation test will be described.
Each additional allowable toner amount S (*) [%] (*: C, M, Y) calculated by the above formula (6) is compared with the reference value Sref = 10 [%],
Sref [%] = 10 [%] ≤ S (*) [%]
In the case of, it is judged to be good (○),
S (*) [%] < Sref [%] = 10 [%]
In the case of, it is judged to be defective (x),
Evaluation (1), which is a judgment result based on test results (1)
Evaluation (2), which is the judgment result based on the test result (2)
Evaluation (3), which is the judgment result based on the test result (3)
are shown in Table 2, respectively.

Note that the reference value Sref [%] = 10 [%] is obtained by considering that the maximum blur width of S1 (*) [g], S2 (*) [g], (*: Y, M, C) is 5%. It is set.

As a comprehensive judgment, if all evaluations are good (○), it is judged to be comprehensively effective (◎), and if there is even one item that is defective (×), there is no overall effect (× ).

Based on the result of the reverse transfer confirmation test, the transfer voltage for printing is applied to the transfer roller 42 corresponding to the color of the toner used for toner disposal, and the applied voltage is set to 0 V for the other transfer rollers 42. , the reverse transfer toner amount S1 (*) stored in each ID waste toner storage unit 24 can be suppressed by reverse transfer at the time of toner disposal under a wide range of temperature and humidity environments from high temperature and high humidity to low temperature and low humidity. rice field.

In the present embodiment, the transfer voltage for printing is applied to the transfer roller 42 corresponding to the color of the toner used for toner disposal, and the voltage applied to the other transfer rollers 42 is 0 [V]. However, it is not limited to this. For example, a transfer voltage at the time of printing is applied to the transfer roller 42 corresponding to the color of the toner used for toner disposal, and the transfer roller A voltage of 0 [V] may be applied to the transfer roller 42 positioned downstream in the paper transport direction.

Further, in the present embodiment, the transfer voltage for printing is applied to the transfer roller 42 corresponding to the color of the toner used for toner disposal, and the voltage applied to the other transfer rollers 42 is 0 [V]. However, the present invention is not limited to this, and the other transfer rollers 42 may be placed in a state in which no transfer is performed. You can respond with

Further, in each embodiment, an image forming apparatus compatible with three colors of toner, cyan (C), magenta (M), and yellow (Y), has been described as an example, but the present invention is not limited to this. For example, the image forming apparatus may support four colors including black (K) and five colors including white (W).

In each embodiment, the processing timing of toner disposal is determined by monitoring the belt count value Cb indicating the usage amount of the transfer belt 43. However, the belt waste toner box 46 (FIG. 3) is not limited to this. ) may be determined based on the belt waste toner count value Th that indicates the amount of waste toner stored in the . Furthermore, a toner disposal button may be provided on the operation input unit 113 so that the user can discard the toner at arbitrary timing instead of predetermined intervals.

As described above, according to the image forming apparatus of the present embodiment, when the toner is discarded as a measure to prevent the belt cleaning blade from turning over, the toner transferred to the transfer belt is reversed even in an unfavorable high-temperature and high-humidity environment. Since the amount of reverse-transferred toner stored in the ID waste toner storage unit 24 increases, the full storage state can be reached early. Therefore, it is possible to solve the problem that the replacement timing of the image forming unit 21 is shortened.

In addition, in the claims and the description of the embodiments, terms such as "upper", "lower", "left", "right", "front", and "back" are used for the sake of convenience. , and does not limit the absolute positional relationship in the state in which the image forming apparatuses are arranged.

In this embodiment, a tandem-type color printer having a plurality of developing units has been described as an example of an image forming apparatus. It is also useful for image forming apparatuses such as Multi-Function Peripheral.

1 image forming apparatus 2 unit assembly 3 slot 4 toner cartridge 6 basket frame 11 roll paper setting section 14 transport roller pair 15 transport roller pair 16 feed roller pair 17 discharge roller pair 18 roll paper (recording paper), 19 roll paper fixing shaft, 21 image forming unit, 22 developing unit, 24 ID waste toner storage unit, 25 photoreceptor drum, 26 charging roller, 27 exposure device, 28 developing roller, 29 developing blade, 30 supply Roller 31 Final toner container 32a Cleaning blade 32b Waste toner receiver 32c Conveying spiral 33 Cutter unit 33a Cutter gear 35 Transfer belt cleaning blade 36 Paper set sensor 38 Writing sensor 38a Lever 38b Light sensor 39 ejection sensor 39a lever 39b optical sensor 41 transfer belt unit 42 transfer roller 43 transfer belt 44 drive roller 45 tension roller 46 belt waste toner box 47 regulation member 48 toner conveying member 49 Driving member 50 Density sensor 51 Contact roller 55 Fixing unit 55a Heat roller 55b Pressure roller 56 Belt motor 57 Operation panel 61 Bottom portion 62 Toner inlet 80 Pull 82 Partition wall 83 Partition wall , 84 Toner containing section in cartridge 90 Bottom section 91 Toner outlet 95 Open/close shutter 95a, 95b, 95c Openings 97 Stirring shaft 99 Passive gear 101 Control section 101a Print control section 101b Toner waste control section , 102 host device, 103 interface control section, 105 memory, 105a ROM 105b RAM, 111 CPU, 112 various sensors, 113 operation input section, 121 process control 122 development voltage control unit 123 supply voltage control unit 124 layer formation voltage control unit 125 charging voltage control unit 126 transfer voltage control unit 127 motor control unit 128 exposure control unit.

Claims (10)

an endless transfer belt;
A developing section for forming a developer image on a built-in electrostatic latent image carrier and a waste developer storage section for storing a waste developer image removed from the electrostatic latent image carrier are integrally formed, a plurality of developing units arranged along the rotational movement direction of the transfer belt ;
a plurality of transfer rollers arranged to face each of the electrostatic latent image bearing members of the plurality of developing units with the transfer belt interposed therebetween, and for transferring the developer image onto the transfer belt;
a developer cartridge integrally provided with a plurality of developer accommodating portions for supplying developers of different colors corresponding to the plurality of developing units;
a transfer control unit that monitors the amount of remaining developer in each of the plurality of developer storage units and the amount of use of the transfer belt, and controls transfer of the developer image;
The transfer control section transfers the developer image using the developer with the largest remaining amount of developer out of the respective amounts of remaining developer to the transfer belt, and the developer with the largest remaining amount of developer is transferred to the transfer belt. and when the amount is less than a predetermined amount, the developer is discarded by transferring the developer image using the developer accommodated on the most downstream side to the transfer belt in the rotational movement direction of the transfer belt. image forming device. 2. The image forming apparatus according to claim 1 , wherein the developer disposal includes transferring the developer image to the transfer belt each time the used amount reaches a predetermined threshold value. a transfer voltage drive control unit that is controlled by the transfer control unit and applies a transfer voltage required for transfer to the plurality of transfer rollers;
The transfer control unit instructs the transfer voltage drive control unit to face the electrostatic latent image carrier that carries the developer image to be transferred onto the transfer belt when the developer is discarded. 2. A transfer voltage applied to a transfer roller positioned downstream of said transfer roller in said rotational movement direction is smaller than a transfer voltage applied to said arranged transfer roller. 3. The image forming apparatus according to 2 above. 3. A transfer voltage necessary for said transfer is applied only to said transfer roller disposed facing said electrostatic latent image bearing member carrying said developer image to be transferred to said transfer belt. 4. The image forming apparatus according to 3 . 3. The method according to claim 1, wherein when monitoring the amount of use of the transfer belt, the amount of movement is counted in units of the movement distance of the transfer belt that rotates corresponding to one rotation of the electrostatic latent image carrier. 5. The image forming apparatus according to any one of Items 1 to 4 . 6. The remaining amount of developer corresponds to the amount of developer obtained by subtracting the amount of consumed developer from the amount of unused developer filled in the developer containing portion. The image forming apparatus according to 1. The consumed amount of developer is a count value counted by the transfer control unit for each unit usage amount of the developer from the number of print dots based on the print data,
7. The image forming apparatus according to claim 6 , wherein the amount of developer when not in use is a value obtained by converting the amount of developer filled in the developer container into the count value. 8. The image forming apparatus according to claim 7 , wherein the count value is reset when the developer cartridge is replaced. 9. The image forming apparatus according to any one of claims 1 to 8 , further comprising a scraping blade for scraping developer adhering to said transfer belt. an endless transfer belt;
a plurality of developing units for forming a developer image on an electrostatic latent image carrier;
a plurality of transfer rollers arranged to face each of the electrostatic latent image bearing members of the plurality of developing units with the transfer belt interposed therebetween, and for transferring the developer image onto the transfer belt;
a developer cartridge integrally provided with a plurality of developer accommodating portions for supplying developers of different colors corresponding to the plurality of developing units;
a transfer control unit that monitors the amount of developer remaining in each of the plurality of developer storage units and controls transfer of the developer image;
When the amount of the developer with the largest remaining amount of developer among the respective amounts of remaining developer is larger than a predetermined amount, the transfer control section performs the development using the developer with the largest remaining amount of developer. The developer image is transferred to the transfer belt, and if the amount is equal to or less than a predetermined amount, the developer image using the developer accommodated on the most downstream side in the rotational movement direction of the transfer belt is transferred to the transfer belt. An image forming apparatus characterized by discarding a developer.

Images