JP7476687B2 - Image forming device - Google Patents

Description

The present invention relates to an electrophotographic image forming apparatus.

Conventional image forming devices supply developer from a developer container into the image forming unit, and run the device idly to rotate the stirring member to uniformly stir the developer in the image forming unit (see, for example, Patent Document 1).

JP 2015-143757 A

However, the conventional technology had the problem that the stirring action of rotating the stirring member could be excessive or insufficient.

The present invention aims to solve these problems and suppress over- and under-stirring.

Therefore, the present invention has a developer container that contains developer, and an image forming unit that receives the developer from the developer container and forms a developer image, and the image forming unit includes a developer storage section that stores the developer, and a stirring member that is provided in the developer storage section and stirs the developer in the developer storage section, and is characterized in that when the developer is replenished from the developer container to the image forming unit, if the print rate of the developer image formed between the time when the remaining amount of developer stored in the developer storage section before the replenishment becomes equal to or less than a specified amount and the time when the developer is replenished is a first print rate, the stirring time of the stirring member is shorter than when the print rate is a second print rate lower than the first print rate.

In this way, the present invention has the effect of preventing over- or under-stirring.

1 is a schematic cross-sectional side view of an image forming apparatus according to a first embodiment of the present invention; FIG. 1 is a schematic cross-sectional side view of an image forming unit according to a first embodiment; FIG. 1 is a block diagram showing a control configuration of an image forming apparatus according to a first embodiment of the present invention; FIG. 1 is a diagram for explaining the configuration of a toner-low detection bar in the first embodiment; FIG. 10 is a diagram for explaining the operation of the toner-low detection bar in the first embodiment. FIG. 1 is a diagram for explaining the configuration of a determination unit in a first embodiment; FIG. 10 is an explanatory diagram of a waveform of a signal detected by a light receiving portion of a photosensor in the first embodiment; 1 is a flowchart showing the flow of agitation processing in the first embodiment. FIG. 13 is a diagram for explaining the relationship between the mixing time and the density unevenness level after replacing the toner cartridge in the first embodiment. FIG. 13 is a schematic cross-sectional side view of an image forming apparatus according to a second embodiment of the present invention; FIG. 11 is a schematic cross-sectional side view of an image forming unit according to a second embodiment of the present invention; FIG. 11 is a block diagram showing a control configuration of an image forming apparatus according to a second embodiment of the present invention. 11 is a flowchart showing the flow of the stirring process in the second embodiment.

Below, an embodiment of an image forming device according to the present invention will be described with reference to the drawings.

Figure 1 is a schematic cross-sectional side view of an image forming apparatus in the first embodiment.

In FIG. 1, the image forming device 1 is a printing device that forms an image using a developer by electrophotography, and in this embodiment, it is a printer capable of color printing. The developer used in this embodiment is a non-magnetic, single-component, negatively charged toner.

The image forming device 1 has image forming units 2Y, 2M, 2C, and 2K, transfer rollers 8Y, 8M, 8C, and 8K, toner cartridges 14Y, 14M, 14C, and 14K, a heating roller 17, a pressure roller 18, a transfer belt unit 19, a paper feed cassette 20, a paper feed roller 21, a transport roller 22, a discharge roller 28, a stacker unit 29, and a concentration sensor 65.

The image forming units 2Y, 2M, 2C, and 2K, which serve as image forming sections, contain toner of the colors yellow (Y), magenta (M), cyan (C), and black (K), respectively, and form toner images by receiving toner corresponding to each color from toner cartridges 14Y, 14M, 14C, and 14K.

In addition, image forming units 2Y, 2M, 2C, and 2K are each detachable from image forming device 1. Image forming units 2Y, 2M, 2C, and 2K are arranged in a row in this order, with image forming unit 2K located at the most downstream side.

In addition, image forming units 2Y, 2M, 2C, and 2K have the same configuration except for the toner they contain, so hereinafter they may be abbreviated to image forming unit 2. The configuration of image forming unit 2 will be described later.

Transfer rollers 8Y, 8M, 8C, and 8K are disposed to face photoconductor drums 3Y, 3M, 3C, and 3K, respectively, with belt 27 (described later) sandwiched therebetween, and transfer the developer image (toner image) formed on the surface of photoconductor drum 3 to medium P. Transfer rollers 8Y, 8M, 8C, and 8K form part of transfer belt unit 19 (described later). In addition, because transfer rollers 8Y, 8M, 8C, and 8K have the same configuration, they may be abbreviated below as transfer roller 8.

Toner cartridges 14Y, 14M, 14C, and 14K, which serve as developer containers, are detachable from image forming device 1 and contain toner. In addition, toner cartridges 14Y, 14M, 14C, and 14K have the same configuration except for the toner contained therein, and therefore may be abbreviated below to toner cartridge (TC) 14.

The toner cartridge 14 (the area surrounded by the dotted line in Figure 2) has two chambers: an unused toner chamber 54 that contains unused toner, and a waste toner chamber 55 that contains waste toner. The unused toner chamber 54 and the waste toner chamber 55 are separated by a wall, so that the unused toner in the unused toner chamber 54 and the waste toner in the waste toner chamber 55 do not mix.

A waste toner transport member B31 is also provided inside the toner cartridge 14. The waste developer removed from the photosensitive drum 3 by the cleaning blade 9 is transported by the waste toner transport member A30, a transport member (not shown), and the waste toner transport member B31, and is finally stored in the waste toner chamber 55. Each transport member is, for example, spiral-shaped.

The heating roller 17 and pressure roller 18 fix the developer images transferred from each image forming unit 2Y, 2M, 2C, and 2K to the medium P by applying heat and pressure to the medium P.

The transfer belt unit 19 is detachable from the image forming device 1 and is disposed below each of the image forming units 2Y, 2M, 2C, and 2K to hold and transport the medium P.

The transfer belt unit 19 also includes a transfer drive roller 23, a transfer driven roller 24, a belt 27, a transfer cleaning blade 25, and a belt waste toner storage section 26.

The transfer drive roller 23 rotates by the motor drive force obtained from the belt drive motor 33 described later, and rotates and conveys the belt 27 in the direction indicated by the arrow A in the figure.

The belt 27 electrostatically attracts the medium P and is rotatably stretched around the transfer drive roller 23 and the transfer driven roller 24, thereby transporting the medium P in the direction indicated by the arrow A in the figure.

The paper feed cassette 20 holds and holds recording media (e.g., printing paper) P.

The paper feed roller 21 sends the media P held in the paper feed cassette 20 one sheet at a time onto the transport path.

The transport rollers 22 transport the medium P sent out by the feed rollers 21 toward the image forming units 2Y, 2M, 2C, and 2K.

The transfer cleaning blade 25 is disposed below the transfer belt unit 19 so as to contact the outer peripheral surface of the belt 27, and is used to remove developer remaining on the outer peripheral surface of the belt 27.

The belt waste toner storage section 26 stores the toner scraped off by the transfer cleaning blade 25.

The discharge roller 28 discharges the fixed medium P outside the device.

The stacker unit 29 stacks media P that has been discharged outside the device.

The sensor unit 65 is disposed opposite the belt 27 of the transfer belt unit 19 and detects the density when density correction is performed.

Figure 2 is a schematic cross-sectional side view of the image forming unit in the first embodiment.

In FIG. 2, the image forming unit 2 has a photoconductor drum 3, a charging roller 4, a charging cleaning roller 5, an LED head 6, a developing roller 7, a cleaning blade 9, a supply roller 10, a stirring bar 11, a developing blade 12, a static elimination light 13, a developing toner tank 15, and a toner-low detection bar 16.

The photosensitive drum 3, which serves as a latent image carrier, is cylindrical and has a surface on which an electrostatic latent image is formed. The photosensitive drum 3 rotates in one direction (counterclockwise in this case) by a motor driving force obtained from a drum drive motor 34, which will be described later. In this embodiment, the photosensitive drum 3 is constructed by providing a photosensitive layer on the surface of a conductive support.

A charging roller 4, an LED head 6, and a developing roller 7 are arranged around the photosensitive drum 3.

The charging roller 4, which serves as a charging member, is given a predetermined bias voltage from the charging roller power source 35 described later, rotates in accordance with the rotation of the photosensitive drum 3, and uniformly charges the surface of the photosensitive drum 3. In this embodiment, the charging roller 4 is a metal shaft on which a semiconductive elastic layer is formed.

The charging cleaning roller 5 is placed in contact with the charging roller 4 and rotates in a driven manner or at a different peripheral speed in conjunction with the rotation of the charging roller 4 to scrape off the toner and toner additives adhering to the charging roller 4.

The LED head 6, which serves as an exposure member, has a plurality of light-emitting elements, LEDs (Light Emitting Diodes), arranged in the main scanning direction (the direction of the rotation axis of the photosensitive drum 3), and a rod lens array. The light emitted by the light-emitting elements according to the print data is imaged on the photosensitive drum 3 by the rod lens array, exposing the charged surface of the photosensitive drum 3 and forming an electrostatic latent image.

The developing roller 7, which serves as a developer carrier, is given a predetermined bias voltage from the developing roller power source 36 described below, rotates in the same direction as the photosensitive drum 3 at the contact point with the photosensitive drum 3, and develops the electrostatic latent image formed on the surface of the photosensitive drum 3 by attaching toner to it. In this embodiment, the developing roller 7 is a metal shaft on which a semiconductive elastic layer is formed.

In addition, a supply roller 10 and a development blade 12 are arranged in this order downstream of the contact point between the development roller 7 and the photosensitive drum 3 in the rotation direction of the development roller 7.

The transfer roller 8 is applied with a predetermined bias voltage from the transfer roller power source 38 described later, and transfers the toner image formed as a developer image on the surface of the photosensitive drum 3 onto the medium P.

When the image forming unit 2 and the transfer belt unit 19 are assembled into the image forming device 1, the photosensitive drum 3 comes into contact with the belt 27, so that the transfer roller 8 is disposed on the opposite side of the photosensitive drum 3 with the belt 27 sandwiched therebetween.

The cleaning blade 9 is disposed downstream of the transfer roller 8 in the rotation direction of the photosensitive drum 3, and is in contact with the photosensitive drum 3 to remove developer remaining on the surface of the photosensitive drum 3 after transfer. In this embodiment, the cleaning blade 9 is a blade made of polyurethane rubber. In addition, a waste toner transport member A30 is provided below the cleaning blade 9.

The supply roller 10, which serves as a developer supply member, is given a predetermined bias voltage from the supply roller power source 37 described below, rotates in the opposite direction to the developing roller 7 at the contact point with the developing roller 7, and supplies toner to the surface of the developing roller 7. In this embodiment, the supply roller 10 is a metal shaft with a foamed silicone rubber layer formed on it.

The stirring bar 11, which serves as a stirring member, is provided in the developing toner tank 15 and stirs the toner in the developing toner tank 15.

The stirring bar 11 is crank-shaped and is attached to the top of the supply roller 10. It rotates to stir the toner around the supply roller 10 and to help transport the toner toward the developing roller 7.

The developing blade 12, which acts as a developer regulating member, is positioned to press against the surface of the developing roller 7, and this pressure regulates the thickness of the developer layer (toner layer) on the developing roller 7, forming a thin layer of toner on the developing roller 7.

The developing blade 12 is also given a predetermined bias voltage from the supply roller power source 37 described below. In this embodiment, the developing blade 12 is formed by bending a long plate-shaped member that is long in the main scanning direction, and is made of stainless steel. The bent portion is also designed to press against the surface of the developing roller 7.

The charge removing light 13 is disposed downstream of the cleaning blade 9 in the direction of rotation of the photosensitive drum 3 without contacting the photosensitive drum 3, and is used to remove residual charge from the photosensitive drum 3.

The charge removal light 13 is composed of, for example, an LED.

The developer toner tank 15, which serves as a developer storage section, stores (stores) the toner.

The toner-low detection bar 16, which serves as a developer amount detection means, is located at a position above the stirring bar 11 in the developer storage unit, and detects the amount of remaining toner by operating differently depending on the relative height between the amount of remaining toner (toner level) in the developing toner tank (developer storage unit) 15 and the installation height of the toner-low detection bar 16. The specific method of detecting the amount of remaining toner will be described later.

Figure 3 is a block diagram showing the control configuration of the image forming device in the first embodiment.

In FIG. 3, the image forming device 1 has a print control unit 39, a high voltage control unit 40, an exposure control unit 41, a power source for static elimination light 42, a fixing control unit 43, a drive control unit 44, a judgment unit 45, a user interface unit 46, a display unit 47, a print data receiving unit 48, a print data conversion unit 49, a drum rotation count measurement unit 50, a head light emission count measurement unit 51, a calculation unit 52, a memory unit 53, and a density sensor 65.

The print control unit 39 includes a control means such as a CPU (Central Processing Unit) and controls the operation of the entire image forming device 1 based on a control program (software) stored in a storage unit such as a memory.

In addition, the print control unit 39 sets a duty flag according to the print duty of the toner image formed after the toner low, and stores the flag in the memory unit 53.

The print control unit 39 also changes the time (mixing time) of the mixing operation by the mixing bar 11 depending on the duty flag.

The print duty as a printing rate indicates the printing rate per printing one sheet of A4 paper.

For example, if the dot count when printing one sheet is (792/5) dot count, the print duty is calculated as (792/5)/(792/5)/1 = 1% duty, and if the dot count when printing three sheets is 9504 dot count, the print duty is calculated as 9504/(792/5)/3 = 20% duty.

In other words, the print duty indicates the ratio of the number of images on which a toner image is formed to the total number of pixels on which a toner image can be formed.

The high voltage control unit 40 controls the charging roller power supply 35, which applies a predetermined voltage to the charging roller 4, the developing roller power supply 36, which applies a predetermined voltage to the developing roller 7, the supply roller power supply 37, which applies a predetermined voltage to the supply roller 10 and the developing blade 12, and the transfer roller power supply 38, which applies a predetermined voltage to the transfer roller 8.

The exposure control unit 41 controls the light emission of the LED head 6.

The static elimination light power supply 42 applies a predetermined voltage to emit the static elimination light 13.

The fixing control unit 43 controls the operation of the heating roller 17 and the pressure roller 18.

The drive control unit 44 controls the transport drive motor 32 that drives the paper feed roller 21 and the transport roller 22, the belt drive motor 33 that drives the transfer drive roller 23, and the drum drive motor 34 that drives the photosensitive drum 3.

The judgment unit 45 judges whether the remaining amount of toner stored in the developing toner tank 15 is equal to or less than a specified amount based on the detection signal of the toner-low detection bar 16, that is, judges whether the toner is low (T/L). The specific method of judging toner low will be described later.

The user interface unit 46 controls the display unit.

The display unit 47 informs the user of the timing for replacing the toner cartridge 14 based on the detection signal from the toner low detection bar 16.

The print data receiving unit 48 receives print data from an external device, such as a personal computer.

The print data conversion unit 49 converts the print data received by the print data receiving unit 48 into head light emission command data for the LED head 6.

The drum rotation speed measuring unit 50, which serves as a latent image carrier rotation speed measuring means, measures the rotation speed of the photosensitive drum 3.

The head light emission count measurement unit 51, which serves as a light emission count measurement means, measures the number of lights emitted by the light-emitting elements of the LED head 6 that correspond to the head light emission command data.

The calculation unit 52, which serves as a calculation means, calculates the print duty for a specified period based on the measurement results of the drum rotation count measurement unit 50 and the head light emission count measurement unit 51.

The memory unit 53 stores the measurement results of the drum rotation speed measurement unit 50 and the head light emission measurement unit 51, and the calculation results of the calculation unit 52.

The density sensor 65 reads and detects the density of the density patch output onto the belt 27 during density correction.

Next, we will explain how to detect the remaining toner amount using the toner-low detection bar 16.

Figure 4 is a diagram explaining the configuration of the toner-low detection bar in the first embodiment.

In FIG. 4, the toner-low detection bar 16 is composed of a crank bar 56, a drive gear 57, and a slit disc 58.

A drive gear 57 is connected to one end of the crank bar 56.

There is a protrusion 59 inside the drive gear 57, and as the drive gear 57 rotates, the protrusion 59 comes into contact with and pushes the end of the crank bar 56, causing the crank bar 56 to rotate.

The slit disc 58 also has a slit 60 as shown in the figure. The slit 60 is provided on the side opposite the convex portion of the crank bar 56, i.e., so that when the convex portion of the crank bar 56 faces downward, the slit 60 faces upward.

Driven by a transmission system from a motor (not shown), the drive gear 57 and the protrusion 59 rotate together at a constant speed. In addition, the protrusion 59 presses the crank bar 56, generating a rotational force for the crank bar, allowing the crank bar 56 and the slit disc 58 to rotate together.

Figure 5 is a diagram explaining the operation of the toner-low detection bar in the first embodiment.

In Figure 5, (a) to (g) show cross sections of the drive gear 57 in various states described below. The curved arrow indicates the direction of rotation of the drive gear 57, and the block arrows indicate the order of operations.

In FIG. 5, in state (a), the crank bar 56 is at the bottom dead center, and the protrusion 59 contacts and pushes the crank bar 56. After that, via state (b), the crank bar 56 reaches the top dead center in state (c).

After the crank bar 56 reaches the top dead center of rotation as shown in state (c), the crank bar 56 is structured to separate from the protrusion 59 and fall under its own weight, so the operation after state (c) differs depending on whether the crank bar 56 is buried in toner or not.

When the crank bar 56 is buried in toner, the rotation of the crank bar 56 follows the rotation of the protrusion 59, as in state (d), state (e), and state (a).

If the crank bar 56 is not buried in toner, as in state (f), the crank bar 56 falls to the bottom dead center due to its own weight. After that, as in states (g) and (a), the crank bar 56 remains stationary at the bottom dead center until the protrusion 59 reaches the bottom position.

Although not shown here, if the top surface level (liquid level) of the toner is within the rotational range of crank bar 56, i.e., between top dead center and bottom dead center, in state (c) and after, crank bar 56 falls from top dead center to the top surface level of the toner under its own weight, and the crank bar remains stationary at the top surface level of the toner until protrusion 59 catches up with crank bar 56. When protrusion 59 catches up with crank bar 56, protrusion 59 contacts crank bar 56 again and pushes it out, returning to state (a).

Next, we will explain the determination unit 45, which receives a signal from the toner-low detection bar 16, which operates as described above, and detects whether the remaining amount of toner is at or below a specified level.

Figure 6 is a diagram explaining the configuration of the determination unit 45 in the first embodiment.

In FIG. 6, the determination unit 45 is composed of a photosensor light-emitting unit 61, a photosensor light-receiving unit 62, a light-emitting unit side light guide path 63 molded from a semi-transparent resin, and a light-receiving unit side light guide path 64.

The light-emitting section side light guide path 63 is provided with one end facing the surface of the disk surface of the slit disk 58, and the other end facing the photosensor light-emitting section 61.

One end of the light receiving section side light guide path 64 is provided facing the back surface of the disk surface of the slit disk 58, and the other end is provided facing the photosensor light receiving section 62.

The height at which the light guides 63 and 64 are installed is set so that the photosensor light receiving section 62 can receive light from the photosensor light emitting section 61 when the crank bar 56 is at bottom dead center, i.e., when the slit 60 is at the top.

At this time, if the rotation of the crank bar 56 is not at the bottom dead center, the position of the slit 60 of the slit disk 58 will deviate from the positions of the light guide paths 63 and 64, blocking the light from the photosensor light emitter 61, and the photosensor light receiver 62 will not be able to receive the light from the photosensor light emitter 61.

The function of the above-mentioned configuration will be explained.

The printing process performed by the image forming device is explained with reference to Figures 1 to 3.

When the print data receiving unit 48 receives print data from a higher-level device such as a personal computer (not shown), the print control unit 39 of the image forming device 1 starts the print process.

The print control unit 39 drives the drum drive motor 34 via the drive control unit 44 to provide a rotational drive force to the photosensitive drum 3, causing the photosensitive drum 3 to rotate at a constant peripheral speed in the direction of the arrow in FIG. 2.

The driving force from the rotation of the photosensitive drum 3 is transmitted by a gear train (not shown), and the developing roller 7, supply roller 10, stirring bar 11, and toner-low detection bar 16 each rotate in the direction of arrow A in FIG. 2, and the waste developer scraped off by the cleaning blade 9 in the operation described below is transported by the waste toner transport member A30. The waste developer transported by the waste toner transport member A30 is then carried by a transport member (not shown), passed to the waste toner transport member B31, and finally stored in the waste toner chamber 55.

The charging roller 4 is not connected to these drive gears, and rotates together with the photosensitive drum 3 in the direction of the arrow in FIG. 2. At this time, a DC voltage is applied from the charging roller power source 35 to the charging roller 4, which is in contact or pressure contact with the surface of the photosensitive drum 3, and the surface of the photosensitive drum 3 is uniformly or evenly charged.

In this embodiment, the aluminum tube of the photoconductor drum 3 is grounded, and the surface of the photoconductor drum 3 is charged to approximately -500 V by applying a DC voltage of -1000 V to the charging roller 4.

Next, the LED head 6 irradiates the charged surface of the photoconductor drum 3 with light corresponding to the head light emission command data, forming an electrostatic latent image on the photoconductor drum 3. In this embodiment, the potential on the photoconductor drum 3 in the exposed area becomes approximately -50V.

The electrostatic latent image on the photosensitive drum 3 is then developed with toner, forming a toner image on the photosensitive drum 3. In this embodiment, a DC voltage of -200V is applied to the developing roller 7 from the developing roller power supply 36. The potential of the thinned toner layer on the developing roller 7 is approximately -50V.

The sum of the potential of the thin toner layer and the voltage applied to the developing roller 7 exceeds the potential of the exposed area on the photoconductor drum 3, so the exposed area on the photoconductor drum 3 is developed with toner.

The sum of the potential of the thin toner layer and the voltage applied to the developing roller 7 does not exceed the potential of the unexposed parts of the photoreceptor drum 3, so the unexposed parts on the photoreceptor drum 3 are not developed with toner.

Meanwhile, the feed roller 21, which is connected to the transport drive motor 32 via the drive control unit 44, is rotated to separate the media P one by one from the paper feed cassette 20 and send them out onto the transport path.

By the rotation of the transport roller 22 connected to the transport drive motor 32, the medium P is transported to the top of the transfer belt unit 19. Furthermore, the drive control unit 44 drives the belt drive motor 33 to apply a rotational drive force to the transfer drive roller 23, causing the belt 27 to rotate in the direction of the arrow A in FIG. 1. The medium P is attracted and held by the belt 27, and is transported by the rotational movement of the belt 27 toward under the image forming unit 2Y.

A DC voltage of +2000V is applied to the transfer roller 8, which is disposed opposite the photosensitive drum 3, from the transfer roller power supply 38.

The toner image formed on the photosensitive drum 3 is transferred onto the medium P by the electric field generated between the transfer roller 8 (+2000 V) and the base tube of the photosensitive drum 3 (grounded).

As belt 27 rotates, medium P first has a Y toner image transferred to it as it passes under image forming unit 2Y. Thereafter, M, C, and K toner images are transferred in order onto medium P each time it passes under image forming units 2M, 2C, and 2K. After medium P passes black image forming unit 2K, a maximum of four color toner images, Y, M, C, and K, are superimposed on medium P.

The medium P then passes between the heating roller 17 and pressure roller 18, which constitute the fixing device, and the toner on the medium P melts due to the heat and pressure and penetrates between the fibers of the medium P, fixing the toner image to the medium P. The medium P with the fixed toner image is discharged by the discharge roller 28 and loaded onto the stacker unit 29.

In addition, a small amount of toner may remain on the photoconductor drum 3 after transfer, but this residual toner (waste developer) is removed by the cleaning blade 9. Here, some of the waste developer and external additives may slip through the cleaning blade 9 and become wrapped around the charging roller 4, but these are removed by the charging cleaning roller 5.

Furthermore, the charge on the photoconductor drum 3 is removed by irradiating the photoconductor drum 3 with the discharge light 13. The surface of the photoconductor drum 3 from which the charge has been removed is charged again by the charging roller 4. In this way, the photoconductor drum 3 is repeatedly used for image formation.

Furthermore, a small amount of toner may remain on the belt 27 after transfer, but this residual toner is removed by the transfer cleaning blade 25. The toner removed by the transfer cleaning blade 25 is transported by a belt waste toner transport member (not shown), such as a spiral or paddle, and collected in the belt waste toner storage section 26. In this way, the belt 27 is repeatedly used for image formation.

Here we explain the operations that take place within the image forming unit.

As described above, the developing roller 7 and the supply roller 10 rotate in the direction of the arrow A in FIG. 2 by receiving the rotational driving force from the photosensitive drum 3.

The toner stored in the developing toner tank 15 is sent to the developing roller 7 by the rotation of the supply roller 10. Because the supply roller 10 and the developing roller 7 rotate in opposite directions at their contact point, the toner is negatively charged by friction.

When the toner sent to the developing roller 7 passes through the contact area with the developing blade 12 due to the rotation of the developing roller 7, it is triboelectrically charged by the developing roller 7 and the developing blade 12 and becomes a thin layer. In this embodiment, a DC voltage of -300V is applied to the supply roller 10 and the developing blade 12 from the supply roller power source 37.

The thin layer of toner on the developing roller 7 is then developed to correspond to the electrostatic latent image formed on the photosensitive drum 3, and the electrostatic latent image becomes a developer image (toner image).

Next, the determination of the remaining toner amount during printing in this embodiment will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram of the waveform of a signal detected by the light receiving portion of the photosensor in the first embodiment.

The photosensor used in this embodiment goes into a "transparent" state when the light-receiving section receives light from the light-emitting section, and during this time outputs 0V as an "OFF signal." On the other hand, when the light-receiving section does not receive light from the light-emitting section, it goes into a "non-transparent" state and outputs 5V as an "ON signal."

Therefore, the determination unit 45 detects the remaining toner amount based on the length of the OFF signal, and when the length of the OFF signal is equal to or greater than a threshold value, it determines that the remaining toner amount is below a specified amount, i.e., a "toner low" state.

Specifically, during printing, when the drive of the photosensitive drum 3 is transmitted by a gear train (not shown) and the drive gear 57 of the crank bar 56 rotates, the protrusion 59 comes into contact with the end of the crank bar 56 and pushes it, causing the crank bar 56 to rotate. However, if the amount of toner remaining in the developing toner tank 15 is greater than the specified amount, for example if the crank bar 56 is buried in the toner, resistance from the toner is encountered during rotation, so even if the crank bar 56 reaches the top dead center of rotation, it cannot rotate under its own weight as described above, and instead rotates at the same speed as the drive gear 57 by being pushed by the protrusion 59 of the drive gear 57.

Therefore, the time during which the photosensor light receiving section 62 receives light from the photosensor light emitting section 61 and outputs an OFF signal is only the time during which the slit 60 of the slit disk 58 passes between the light guides 63 and 64 at the same speed as the rotational speed of the drive gear 57. This state is the toner full state shown by the solid line in Figure 7.

On the other hand, when the amount of toner remaining in the developing toner tank 15 decreases, there is no toner near the crank bar 56. In this case, the crank bar 56 is no longer subjected to resistance from the toner when rotating, so when it reaches the top dead center of rotation as described above, the crank bar 56 rotates under its own weight and reaches the bottom dead center earlier than when it is rotated by the drive gear 57. The crank bar 56 remains at the bottom dead center until the protrusion 59 comes into contact with the crank bar 56 again due to the rotation of the drive gear 57. During this time, the photosensor light receiving portion 62 continues to output the OFF signal receiving light from the photosensor light emitting portion 61 for a longer period of time.

Until the remaining toner amount falls below the bottom dead center of rotation, the less the remaining toner amount, the longer the time for which the OFF signal is output in one cycle, but in this embodiment, the threshold value is set to 0.46 times the rotation period T of the drive gear 57. In other words, the state in which the length of the OFF signal is longer than 0.46T is the toner-low state shown by the dotted line in Figure 7.

In this embodiment, when the determination unit 45 detects that the length of the OFF signal (detection signal of the toner-low detection bar 16) is equal to or greater than the threshold value two or more times in succession, it determines that the toner is low (the remaining amount of toner stored in the developing toner tank 15 is equal to or less than a specified amount) and displays a message on the display unit 47 encouraging the replacement of the toner cartridge 14.

Note that even if a message prompting the user to replace the toner cartridge 14 is displayed on the display unit 47, this does not immediately stop the printing process. Printing can continue until the print control unit 39 next determines that the toner cartridge is empty (T/E). When the print control unit 39 determines that the toner cartridge is empty (T/E), the printing process stops and cannot be resumed unless the toner cartridge 14 is replaced.

The image forming device 1 accepts replacement of the toner cartridge 14.

When toner is replenished from a replaced toner cartridge 14, the image forming device 1 performs a stirring operation (idle rotation) to suppress the occurrence of density unevenness due to changes in the toner characteristics in the developing toner tank 15.

Here, the idle time after replacing the toner cartridge 14 can be expressed as the sum of two terms, as shown in the following equation (1).

Idle time=(toner transport and supply time)+toner mixing time (1)
In equation (1) (toner transport and supply time), as long as the installation height of the toner-low detection bar 16 is the same, the toner supply amount and supply time do not change depending on the printing duty, so what changes due to the increase in idling time is the mixing time.

In the following, mixing time will be explained as idle time.

In this embodiment, a method using a free-fall rotating bar to detect toner-low has been described, but the method is not limited to this and may also use a method using transmissive optical detection.

In addition, the image forming device 1 performs density correction after the stirring operation.

Next, the mixing process performed by the image forming device will be described with reference to Figures 1 to 7, following the steps indicated by S in the flow chart of the mixing process in the first embodiment of Figure 8.

S101: The print control unit 39 determines whether or not the toner is low using the determination unit 45. If it is determined that the toner is low, the process proceeds to step S102. If it is not determined that the toner is low, the print process continues.

S102: The print control unit 39 displays a message on the display unit 47 encouraging the user to replace the toner cartridge 14.

S103: The print control unit 39 starts measuring the drum count and dot count using the drum rotation count measurement unit 50 and the head light emission count measurement unit 51.

The drum count is a measurement of the number of rotations (printing distance) of the photosensitive drum 3, and counts up as long as the photosensitive drum 3 rotates. In this embodiment, one drum count advances when one sheet of A4 paper (210 mm wide x 297 mm long) is printed.

The dot count is the number of dots that light up when the LED head 6 forms dots that match the print pattern, and is counted up each time they light up. In this embodiment, when printing the print area excluding the margins of an A4 sheet of paper in solid colors, the LED head is defined as lighting up 5% of that area as a 792 dot count.

In this embodiment, the cumulative values of the drum count and dot count after the toner low are stored in the memory unit 53, but these cumulative values are reset to zero when the toner cartridge 14 is replaced.

S104: The print control unit 39 sets each duty flag, high duty, medium duty, and low duty, according to the print duty calculated by the calculation unit 52, and stores the flags in the memory unit 53.

At this time, the calculation unit 52 calculates the print duty based on the drum count and dot count from when the toner low was determined until the toner cartridge 14 was replaced, that is, the drum count and dot count stored in the memory unit 53. The reason why the print duty is calculated based on the count after the toner low will be explained later.

The print duty is calculated using the following formula (1) based on the drum count and dot count stored in the memory unit 53.

Print duty=dot count/(792/5)/drum count (1)
The print duty calculated by the above formula indicates the printing rate of the toner image formed from when the toner-low state before toner replenishment is determined until the toner cartridge 14 is replaced.

In this embodiment, the predetermined period is defined as the period from when the toner low state is determined to be low until the toner cartridge 14 is replaced, that is, the period from when the remaining amount of toner stored in the developing toner tank 15 falls below a specified amount until the toner is replenished and the determination unit 45 determines that the toner is full.

In addition, depending on the calculation result of the calculation unit 52, the print control unit 39 sets a high duty flag as the first print rate when the print duty is high, such as 20% or more, sets a low duty flag as the second print rate when the print duty is low, such as 1% or less, and sets a medium duty flag in other cases.

In this way, the print control unit 39 sets a duty flag for high duty, medium duty, or low duty according to the print duty of the toner image formed during a specified period before toner replenishment, and stores the flag in the memory unit 53.

In this embodiment, a high duty cycle is defined as a print duty of 20% or more, and a low duty cycle is defined as a print duty of 1% or less, but this is not limited to this.

S105: The print control unit 39 determines whether the toner cartridge 14 has been replaced, and if it determines that it has been replaced, proceeds to step S108, and if it determines that it has not been replaced, proceeds to step S106.

The replacement of the toner cartridge 14 may be detected by attaching a contact or non-contact tag to the toner cartridge 14, storing the unique identification information of the toner cartridge 14 in the tag, and detecting that the unique identification information of the toner cartridge 14 has changed when the tag information is read by the device.

S106: The print control unit 39 determines whether toner is empty (T/E).

In this embodiment, the criterion for determining whether the toner is empty is when the dot count value measured in step S103 exceeds 118,800 (A4, 5% duty, 150 sheets). If it is determined that the toner is empty, the process proceeds to step S107, and if it is determined that the toner is not empty, the process proceeds to step S104.

S107: The print control unit 39 forcibly terminates printing and accepts the user's request to replace the toner cartridge 14.

Here, the duty flag is updated repeatedly until the toner cartridge 14 is replaced. The timing of the judgment can be, for example, after printing one sheet if the print data is for one sheet, after printing 10 consecutive sheets if the print data is for 10 sheets, or after printing 50 consecutive sheets if the print data is large, such as for 100 sheets, and the judgment can be made after printing every 50 consecutive sheets and at the 50th and 100th sheets.

S108: After replacing the toner cartridge 14, the print control unit 39 ends the drum count and dot count measurement by the drum rotation count measurement unit 50 and the head light emission count measurement unit 51.

At this time, the memory unit 53 stores the drum count, cumulative dot count value, and duty flag from when the toner low was determined to be low until the toner cartridge 14 was replaced.

S109: The print control unit 39 hides the message on the display unit 47 prompting the user to replace the toner cartridge 14.

S110: The print control unit 39 determines whether the duty flag stored in the memory unit 53 is a high duty flag (first printing rate), and if it is determined that it is a high duty flag, proceeds to step S111, and if it is determined that it is not a high duty flag, proceeds to step S112.

S111: The print control unit 39 performs the stirring operation for a short period of time (40 seconds in this embodiment) after replacing the toner cartridge 14.

S112: The print control unit 39 determines whether the duty flag stored in the memory unit 53 is a low duty flag (second printing rate), and if it is determined that it is a low duty flag, proceeds to step S114, and if it is determined that it is not a low duty flag, proceeds to step S113.

S113: The print control unit 39 performs the stirring operation for a medium period (2 minutes 30 seconds) after replacing the toner cartridge 14.

S114: The print control unit 39 performs the stirring operation for a long period of time (3 minutes) after replacing the toner cartridge 14.

S115: After the stirring operations of steps S111, S113, and S114 are completed, the print control unit 39 performs density correction.

Density correction involves developing a density patch for at least one of the image forming units 2Y, 2M, 2C, and 2K in which the toner cartridge 14 has been replaced, transferring it onto the belt 27, measuring the density of the density patch with the density sensor 65, and ending if the measured density value is within a specified range. If the density of the density patch is not within the specified range, the high voltage control unit 40 and exposure control unit 41 adjust the bias and head light amount so that the density of the density patch is within the specified range.

In this way, when the image forming unit 2 is replenished with toner from the toner cartridge 14, if the print duty of the toner image formed during a certain period before the toner replenishment is high duty (first printing rate), the print control unit 39 shortens the stirring time by the stirring bar 11 compared to when the print duty is low duty (second printing rate) that is lower than the high duty (first printing rate).

Next, the relationship between the mixing time after replacing the toner cartridge 14 and the level of uneven density will be described with reference to FIG. 9. FIG. 9 is a diagram for explaining the relationship between the mixing time after replacing the toner cartridge 14 in the first embodiment and the level of uneven density. Also shown are the cases where the print duty for a certain period before toner replenishment is low duty and high duty.

The density unevenness level here is a 10-level assessment of the appearance of density unevenness by visual inspection, with level 10 indicating no density unevenness and level 1 indicating the worst degree of density unevenness. In this example, level 7 was determined to be the level at which density unevenness is OK.

In addition, uneven density refers to a state in which areas of high and low density appear even though the density should be uniform when the entire surface is printed in solid color.

In addition, one of the reasons for the uneven density is that when the toner cartridge 14 is replaced with a new one, the characteristics of the toner remaining in the developing toner tank 15 differ from the characteristics of the toner supplied to the developing toner tank 15 from the new toner cartridge 14 after replacement, and these toners may not be mixed sufficiently, in which case uneven density will be noticeable in subsequent printing.

In addition, as shown in Figure 9, the level of density unevenness worsens when the print duty for a certain period before toner replenishment is low rather than high.

This is because, in low-duty printing, the toner that is not developed is more likely to be agitated in the developing toner tank 15, and the friction and pressure between components and between the toner particles themselves cause greater changes in the toner characteristics, resulting in a greater difference between the characteristics of the toner remaining in the developing toner tank 15 and the toner supplied to the developing toner tank 15 from the replaced new toner cartridge 14. In contrast, in high-duty printing, the toner is consumed while the changes in the toner characteristics in the developing toner tank 15 are still small, so the difference between the characteristics of the toner remaining in the developing toner tank 15 and the toner supplied to the developing toner tank 15 from the replaced new toner cartridge 14 is smaller.

This change in toner characteristics during low-duty printing is particularly noticeable after the toner low determination. Before the toner low determination, even if there is a change in the toner characteristics, it is stirred and mixed with toner that has not undergone a change in the toner characteristics, so it can be considered that there is almost no change in the average toner characteristics in the developing toner tank 15. However, after the toner low determination, no more toner is supplied from the toner cartridge 14 to the developing toner tank 15, the amount of toner in the developing toner tank 15 that has not undergone a change in the toner characteristics is reduced, and even if the toner is stirred and mixed, the effects of the change in the toner characteristics remain strong.

Therefore, in this embodiment, the count after the toner low is used to calculate the print duty in step S104 in FIG. 8. This allows the mixing time to be set appropriately in the subsequent steps S111, S113, and S114.

In Figure 9, in both cases where the print duty for a certain period before toner replenishment is low duty and where the print duty is high duty, the density unevenness is improved by increasing the mixing time after replacing the toner cartridge 14.

This is because the toner with large changes in characteristics remaining in the developing toner tank 15 is stirred and mixed with the unused toner supplied to the developing toner tank 15 from the toner cartridge 14, and the effect of the average toner characteristic changes in the developing toner tank 15 becomes smaller as the stirring time increases.

When the printing duty for a certain period before toner replenishment is low duty versus high duty, the amount of toner with large characteristic changes present in the developing toner tank 15 is greater in the low duty case, and the level of density unevenness is also lower in the low duty case.

Therefore, the mixing time required until the concentration unevenness level becomes good (OK) is longer in the case of low duty than in the case of high duty.

In other words, when toner is replenished to the image forming unit 2 by replacing the toner cartridge 14, if the print duty of the toner image formed during the specified period before the toner replenishment is low (second print rate), the mixing time is longer than when the print duty is high (first print rate).

In addition, when toner is replenished to the image forming unit 2 by replacing the toner cartridge 14, if the print duty of the toner image formed during the specified period before the toner replenishment is high (first print rate), the mixing time is shorter than when the print duty is low (second print rate).

In the comparative image forming device, after replacing the toner cartridge 14 when the toner is empty, a stirring operation is performed, and then density correction is performed.

In addition, in the image forming device of the comparative example, the stirring operation is performed for one minute regardless of the print duty. Therefore, if low-duty printing was performed before replacing the toner cartridge 14, there may be a large difference in the characteristics between the remaining toner in the image drum unit (ID) after replacing the toner cartridge 14 and the unused toner in the toner cartridge 14, and the toner may not mix uniformly, resulting in abnormal density unevenness (NG).

On the other hand, when high duty printing was performed before replacing the toner cartridge 14, the level of density unevenness was good (OK), but after replacing the toner cartridge 14, there was almost no difference in the characteristics between the remaining toner in the ID and the unused toner in the toner cartridge 14, and even though a long stirring operation was not necessary, extra stirring time was reserved, which resulted in an increase in the stirring time and ID count.

Therefore, in this embodiment, the mixing time is set to 3 minutes when the print duty is low during the specified period before toner replenishment, and 40 seconds when the print duty is high, resulting in good density unevenness levels for both low and high duty. Also, the mixing time for high duty can be shortened compared to the comparative example.

In other words, by making the mixing time shorter in the case of high duty than in the case of low duty, the ID count can be reduced, thereby reducing downtime that is not related to printing operations.

Therefore, in this embodiment, it is possible to suppress over- or under-stirring operation.

In this way, in the first embodiment, when toner is replenished to the image forming unit 2 by replacing the toner cartridge 14, if the print duty of the toner image formed during the specified period before the toner replenishment is high duty (first printing rate), the stirring time of the stirring bar 11 is made shorter than when the print duty is low duty (second printing rate) that is lower than the high duty (first printing rate), thereby preventing over- or under-stirring operation.

In addition, even if the mixing time is shortened when high-duty (first printing rate) printing is performed during the specified period before toner replenishment, the difference in characteristics between the toner in the image forming unit 2 and the toner in the toner cartridge 14 is smaller than when low-duty printing is performed, so the occurrence of uneven density due to the difference in toner characteristics before and after replacing the toner cartridge 14 is reduced, and unnecessary increases in mixing time and ID counts can be suppressed.

In addition, by lengthening the mixing time when low-duty (second printing rate) printing is performed during the specified period before toner replenishment, the toner is thoroughly mixed and the low-duty toner is uniformly mixed in the unused toner, suppressing the difference in toner characteristics before and after replacing the toner cartridge 14 and reducing the occurrence of density unevenness.

In addition, because uneven density of the density patch is reduced when density correction is performed, the density read by the density sensor becomes stable, allowing a constant density to be stably output.

As described above, in the first embodiment, when toner is replenished to the image forming unit by replacing the toner cartridge, the effect of suppressing excess or deficiency of the stirring operation can be obtained.

In addition, it has the effect of suppressing the occurrence of uneven concentration and preventing unnecessary increases in mixing time and ID count.

In addition, it has the effect of being able to stably output a constant concentration.

The configuration of the second embodiment differs from that of the first embodiment in the configuration for replenishing toner from the toner cartridge 14 to the developing toner tank 15.

In the following, parts similar to those in the first embodiment described above will be given the same reference numerals and their explanation will be omitted.

Figure 10 is a schematic cross-sectional side view of an image forming apparatus in the second embodiment.

In FIG. 10, the image forming device 101 is configured with image forming units 102Y, 102M, 102C, and 102K for four colors, yellow (Y), magenta (M), cyan (C), and black (K), arranged in this order.

Figure 11 is a schematic cross-sectional side view of the image forming unit in the second embodiment.

In FIG. 11, the image forming unit 102 has a toner supply port 166 provided at the top of the developing toner tank 15, a toner supply section 167 that is connected to the toner cartridge 14 and serves as a developer supply section that supplies toner, a supply spiral 168 that is rotatably provided inside the toner supply section 167, and a supply drive gear 169 that rotates and drives the supply spiral 168.

The toner cartridge 14 (encircled by a dotted line in FIG. 11) is removably connected to the top of the toner supply unit 167, and the toner in the toner cartridge 14 is supplied to the developing toner tank 15 through the toner supply port 166.

In this embodiment, a fixed amount of toner is supplied from the toner cartridge 14 to the image forming unit 102 via the toner supply unit 167.

The toner cartridge 14 also has two chambers: an unused toner chamber 54 and a waste toner chamber 55.

Figure 12 is a block diagram showing the control configuration of an image forming device in the second embodiment.

In FIG. 12, the image forming apparatus 101 has a drive control unit 44 that controls the driving of the conveyor drive motor 32, the belt drive motor 33, the drum drive motor 34, and the refill drive motor 170.

The supply drive motor 170 is connected to the supply drive gear 169 and operates the supply spiral 168.

The function of the above-mentioned configuration will be explained.

The stirring process performed by the image forming device will be described with reference to Figures 10 to 12, following the steps indicated by S in the flow chart showing the flow of the stirring process in the second embodiment of Figure 13.

S201: The print control unit 39 determines whether or not the toner is low using the determination unit 45. If it is determined that the toner is low, the process proceeds to step S202. If it is not determined that the toner is low, the print process continues.

S202: The print control unit 39 displays a message on the display unit 47 encouraging the user to replace the toner cartridge 14.

S203: The print control unit 39 starts measuring the drum count and dot count using the drum rotation count measurement unit 50 and the head light emission count measurement unit 51. Note that the method of measuring the drum count and dot count is the same as in the first embodiment, so a description thereof will be omitted.

In this embodiment, the drum count and dot count are reset to their initial values (zero) when toner is replenished (step S207), and are measured from when the toner low level is determined until toner is replenished.

S204: The print control unit 39 calculates the print duty using the calculation unit 52, sets each duty flag of high duty (first printing rate), medium duty, and low duty (second printing rate) according to the calculation result, and stores the flag in the memory unit 53. Note that the method of calculating the print duty is the same as in the first embodiment, so the explanation is omitted.

S205: The print control unit 39 determines whether the dot count has exceeded 118,800. If it determines that the dot count has exceeded 118,800, it proceeds to step S206. If it determines that the dot count has not exceeded 118,800, it proceeds to step S204.

The dot count value of 118,800 here is the count value when printing 150 sheets of A4 size at 5% duty, just like in the first embodiment.

The duty flag is updated repeatedly until the dot count exceeds 118,800. In addition, the timing of the determination as to whether the dot count has exceeded 118,800 is performed each time the dot count changes.

The calculated print duty also indicates the printing rate of the toner image formed during a specified period before toner replenishment (the period from when the remaining amount of toner stored in the developing toner tank 15 falls below a specified amount to when toner is replenished).

In this way, the print control unit 39 sets a duty flag for high duty, medium duty, or low duty according to the print duty of the toner image formed during a specified period before toner replenishment, and stores the flag in the memory unit 53.

S206: The print control unit 39 ends the drum count and dot count measurement by the drum rotation count measurement unit 50 and the head light emission count measurement unit 51.

S207: The print control unit 39 supplies toner to the image forming unit 2 via the toner supply unit 167.

The print control unit 39 operates the supply drive motor 170 to operate the supply spiral 168, and performs toner supply by supplying (transporting) a fixed amount of toner from the unused toner chamber 54 to the developing toner tank 15 via the toner supply unit 167.

S208: The print control unit 39 determines whether or not the toner is full. If it is determined that the toner is full, the process proceeds to step S209. If it is not determined that the toner is full, the process proceeds to step S207.

In this embodiment, the print control unit 39 determines that the toner is full when it detects that the length of the OFF signal detected by the toner remaining amount detection unit 26 is equal to or less than a threshold value. The threshold value is set to 0.46 times the rotation period T of the drive gear 57. Through this series of controls, after a toner low determination, toner is replenished until a toner full state is detected.

Note that the operations from step S210 to step S215 are similar to steps S110 to S115 of the first embodiment shown in FIG. 10, so a description thereof will be omitted.

In addition, in this embodiment, the calculation of the print duty is started after the toner low is detected, but this is not limited to this and may be started when the previous toner supply is completed.

In addition, in this embodiment, the timing to stop toner supply is determined based on whether or not a toner full state is detected, but this is not limited to this, and the timing may be determined based on whether or not the number of rotations of the toner supply motor 170 from the start of toner supply exceeds a threshold value.

In this way, in the second embodiment, when toner is replenished to the image forming unit 2 via the toner replenishment section 167, if the print duty of the toner image formed during a certain period before the toner replenishment is high duty (first printing rate), the stirring time of the stirring bar 11 is made shorter than when the print duty is low duty (second printing rate) that is lower than the high duty (first printing rate), thereby preventing over- or under-stirring operation.

It also helps prevent uneven concentration and unnecessary increases in mixing time and ID count.

In addition, it is possible to stably output a constant concentration.

As described above, when toner is replenished to the image forming unit through the toner replenishment section, the effect of suppressing excess or deficiency of the stirring operation is obtained.

In addition, it has the effect of suppressing the occurrence of uneven concentration and preventing unnecessary increases in mixing time and ID count.

In addition, it has the effect of being able to stably output a constant concentration.

In the first and second embodiments, the image forming device is described as a printer, but is not limited to this and may be a copier, a facsimile machine, a multifunction peripheral (MFP), etc.

LIST OF SYMBOLS 1, 101 Image forming apparatus 2 (2Y, 2M, 2C, 2K), 102 Image forming unit 3 (3Y, 3M, 3C, 3K) Photoconductor drum 4 Charge roller 5 Charge cleaning roller 6 LED head 7 Development roller 8 (8Y, 8M, 8C, 8K) Transfer roller 9 Cleaning blade 10 Supply roller 11 Stirring bar 12 Development blade 13 Discharge light 14 (14Y, 14M, 14C, 14K) Toner cartridge 15 Development toner tank 16 Toner low detection bar 17 Heating roller 18 Pressure roller 19 Transfer belt unit 20 Paper feed cassette 21 Paper feed roller 22 Transport roller 23 Transfer drive roller 24 Transfer driven roller 25 Transfer cleaning blade 26 Belt waste toner storage section 27 Belt 28 Discharge roller 29 Stacker section 30 Waste toner transport member A
31 Waste toner transport member B
32 Conveyor drive motor 33 Belt drive motor 34 Drum drive motor 35 Power source for charging roller 36 Power source for developing roller 37 Power source for supply roller 38 Power source for transfer roller 39 Print control unit 40 High voltage control unit 41 Exposure control unit 42 Power source for static elimination light 43 Fixing control unit 44 Drive control unit 45 Determination unit 46 User interface unit 47 Display unit 48 Print data receiving unit 49 Print data conversion unit 50 Drum rotation number measurement unit 51 Head light emission number measurement unit 52 Calculation unit 53 Memory unit 54 Unused toner chamber 55 Waste toner chamber 56 Crank bar 57 Drive gear 58 Slit disk 59 Protrusion 60 Slit 61 Photosensor light emitting unit 62 Photosensor light receiving unit 63 Light guiding path on the light emitting unit side 64 Light guiding path on the light receiving unit side 65 Density sensor 166 Toner supply port 167 Toner supply section 168 Supply spiral 169 Supply drive gear 170 Supply drive motor

Claims (4)

a developer container that contains a developer;
an image forming section which receives the developer from the developer container and forms a developer image;
having
The image forming unit includes:
A developer storage section for storing the developer;
a stirring member provided in the developer storage section and configured to stir the developer in the developer storage section;
Including,
When the developer is replenished from the developer container to the image forming unit,
an image forming apparatus characterized in that, when the printing rate of the developer image formed between the time when the remaining amount of developer stored in the developer storage section before the replenishment falls below a specified amount and the time when the developer is replenished is a first printing rate, the stirring time of the stirring member is shorter than when the printing rate is a second printing rate lower than the first printing rate. 2. The printing device according to claim 1,
When the developer is replenished to the image forming unit by replacing the developer container,
an image forming apparatus characterized in that, when the printing rate of the developer image formed between the time when the remaining amount of developer stored in the developer storage section before the replenishment falls below a specified amount and the time when the developer is replenished is a first printing rate, the stirring time of the stirring member is shorter than when the printing rate is a second printing rate lower than the first printing rate. 2. The printing device according to claim 1,
The image forming unit includes:
a developer supply unit connected to the developer container and configured to supply the developer;
When the developer is replenished to the image forming unit through the developer replenishment unit,
an image forming apparatus characterized in that, when the printing rate of the developer image formed between the time when the remaining amount of developer stored in the developer storage section before the replenishment falls below a specified amount and the time when the developer is replenished is a first printing rate, the stirring time of the stirring member is shorter than when the printing rate is a second printing rate lower than the first printing rate. 4. The image forming apparatus according to claim 1,
The image forming apparatus according to the present invention, wherein the printing rate is a ratio of the number of images on which the developer image is formed to the total number of pixels on which the developer image can be formed.

Images