Patent Description:
A development cartridge accommodates the toner and supplies the toner to the electrostatic latent image formed on the photoconductor to form the visible toner image. When the toner accommodated in the development cartridge is exhausted, the development cartridge may be replaced with a new development cartridge or the development cartridge may be refilled with toner
<CIT> describes a visualization agent quantity display control system. <CIT> describes an image forming device and method of supplying developer. <CIT> describes a device for precisely controlling toner concentration. <CIT> describes a method of estimating toner levels by maintaining a running pulse width count, sensing, and comparing to the expected width.

The present invention provides an image forming apparatus according to claim <NUM>, a method of estimating a toner remaining rate of a development cartridge according to claim <NUM> and a computer-readable non-transitory recording medium storing instructions executable by a processor according to claim <NUM>.

<FIG> is a schematic external perspective view of an example of an image forming apparatus <NUM> to which toner is refilled by being combined with a toner refill cartridge <NUM>. <FIG> is a schematic configuration diagram of an example of the image forming apparatus <NUM> of <FIG>. <FIG> is a perspective view of an example of a development cartridge <NUM> that may be employed in the image forming apparatus <NUM> of <FIG>.

Referring to <FIG>, the image forming apparatus <NUM> may include a main body <NUM> and the development cartridge <NUM> attachable to and detachable from the main body <NUM>. A door <NUM> may be provided at the main body <NUM>. The door <NUM> may open or close a portion of the main body <NUM>. In <FIG>, the door <NUM> opening an upper portion of the main body <NUM> is illustrated, but when required, a door opening a side portion or all of the main body <NUM> may be employed. A user may open the door <NUM> to mount or remove the development cartridge <NUM> on or from the main body <NUM>. A communicating portion <NUM> may be provided at the main body <NUM> such that the development cartridge <NUM> may access a toner refilling portion <NUM> from the outside of the main body <NUM> while being mounted on the main body <NUM>. The main body <NUM> may be mounted with the development cartridge <NUM> that forms a toner image by supplying toner accommodated in a toner container <NUM> to an electrostatic latent image formed on a photoconductor. The communicating portion <NUM> may be provided on an outer surface of the main body <NUM> to combine the toner refill cartridge <NUM> for refilling the toner in the toner container <NUM> by being connected to the toner refilling portion <NUM> of the development cartridge <NUM>. The communicating portion <NUM> may be provided at a position close to a front portion <NUM>-<NUM> of the main body <NUM>. Since the front portion <NUM>-<NUM> faces the user, the user may easily access the communicating portion <NUM>. Accordingly, a toner refill job using the toner refill cartridge <NUM> may be easily performed via the communicating portion <NUM>. The communicating portion <NUM> may be provided at a top surface <NUM>-<NUM> of the main body <NUM>. The toner refilling portion <NUM> may be provided below the communicating portion <NUM>. The communicating portion <NUM> and the toner refilling portion <NUM> may be aligned in a vertical direction. The toner refill cartridge <NUM> may access the toner refilling portion <NUM> through the communicating portion <NUM> from the above of the main body <NUM>.

A photosensitive drum <NUM> is an example of a photoconductor on which an electrostatic latent image is formed, and may include a cylindrical metal pipe and a photosensitive layer formed on an outer circumference of the cylindrical metal pipe and having photoconductivity. A charging roller <NUM> is an example of a charger that charges a surface of the photosensitive drum <NUM> with uniform electric potential. A charging bias voltage may be applied to the charging roller <NUM>. A corona charger (not shown) may be used instead of the charging roller <NUM>. A developing roller <NUM> may supply the toner to an electrostatic latent image formed on a surface of the photosensitive drum <NUM> to develop the electrostatic latent image.

A supply roller <NUM> may attach the toner to the developing roller <NUM>. A supply bias voltage may be applied to the supply roller <NUM> to attach the toner to the developing roller <NUM>. A regulating member <NUM> may regulate an amount of toner attached to the surface of the developing roller <NUM>. The regulating member <NUM> may be, for example, a regulating blade whose tip contacts the developing roller <NUM> with certain pressure. A cleaning member <NUM> may remove residual toner and impurities from the surface of the photosensitive drum <NUM> before charging. The cleaning member <NUM> may be, for example, a cleaning blade whose tip contacts the surface of the photosensitive drum <NUM>. Meanwhile, hereinafter, the impurities removed from the surface of the photosensitive drum <NUM> are referred to as waste toner.

An optical scanner <NUM> may scan light modulated according to image information on the surface of the photosensitive drum <NUM> charged with uniform electric potential. As the optical scanner <NUM>, for example, a laser scanning unit (LSU) scanning light emitted from a laser diode on the photosensitive drum <NUM> by deflecting the light in a main scanning direction by using a polygon mirror may be employed.

A transfer roller <NUM> is an example of a transfer unit provided to face the photosensitive drum <NUM> to form a transfer nip. A transfer bias voltage for transferring a toner image developed on the surface of the photosensitive drum <NUM> onto a print medium P may be applied to the transfer roller <NUM>. A corona transfer unit may be used instead of the transfer roller <NUM>.

The toner image transferred to the surface of the print medium P by the transfer roller <NUM> may be maintained on the surface of the print medium P via electrostatic attraction. A fuser <NUM> may apply heat and pressure onto the toner image to fuse the toner image on the print medium P, thereby forming a permanent print image on the print medium P.

The development cartridge <NUM> according to the current example may include a developing portion <NUM> where the photosensitive drum <NUM> and the developing roller <NUM> are provided, a waste toner container <NUM> where the waste toner removed from the photosensitive drum <NUM> is accommodated, and the toner container <NUM> connected to the developing portion <NUM> and accommodating the toner. In order to refill the toner in the toner container <NUM>, the development cartridge <NUM> may include the toner refilling portion <NUM> connected to the toner container <NUM>. The toner refilling portion <NUM> provides an interface between the toner refill cartridge <NUM> and the development cartridge <NUM> described below. The development cartridge <NUM> may be an integrated development cartridge including the developing portion <NUM>, the waste toner container <NUM>, the toner container <NUM>, and the toner refilling portion <NUM>.

A portion of an outer circumference of the photosensitive drum <NUM> may be exposed to an outside of a housing. The transfer roller <NUM> may contact the exposed portion of the photosensitive drum <NUM> to form a transfer nip. A conveying member conveying the toner towards the developing roller <NUM> may be provided at the developing portion <NUM>. The conveying member may also perform a function of filling the toner to certain electric potential by stirring the toner.

The waste toner container <NUM> may be provided above the developing portion <NUM>. The waste toner container <NUM> may form a light path <NUM> by being spaced apart from the developing portion <NUM> upward. The waste toner removed from the photosensitive drum <NUM> by the cleaning member <NUM> may be accommodated in the waste toner container <NUM>. The waste toner removed from the surface of the photosensitive drum <NUM> may be transported into the waste toner container <NUM> by a waste toner transport member <NUM> through <NUM>. A shape and number of waste toner transport members are not specifically limited. The suitable number of waste toner transport members may be provided at suitable positions for effectively distributing the waste toner in the waste toner container <NUM> in consideration of the volume or shape of the waste toner container <NUM>.

The toner container <NUM> may accommodate the toner by being connected to the toner refilling portion <NUM>. The toner container <NUM> may be connected to the developing portion <NUM> by a toner supply unit <NUM> as indicated by broken lines in <FIG>. As shown in <FIG>, the toner supply unit <NUM> may be connected to the developing portion <NUM> by penetrating the waste toner container <NUM> in a vertical direction. The toner supply unit <NUM> may be provided outside a valid width of an exposure light L such as not to interfere with the exposure light L scanned in the main scanning direction by the optical scanner <NUM>.

A Toner supply member <NUM> through <NUM> for supplying the toner to the developing portion <NUM> through the toner supply unit <NUM> may be provided at the toner container <NUM>. A shape and number of toner supply members are not specifically limited. The suitable number of toner supply members may be provided at suitable positions of the toner container <NUM> to effectively provide the toner to the developing portion <NUM> in consideration of the volume or shape of the toner container <NUM>. The toner supply member <NUM> may transfer the toner to the toner supply unit <NUM>.

An image forming operation according to the above configuration will be briefly described. The charging bias voltage may be applied to the charging roller <NUM> and the photosensitive drum <NUM> may be charged to uniform electric potential. The optical scanner <NUM> may scan the light modulated according to the image information on the photosensitive drum <NUM> to form the electrostatic latent image on the surface of the photosensitive drum <NUM>. The supply roller <NUM> may attach the toner on the surface of the developing roller <NUM>. The regulating member <NUM> may form a toner layer of a uniform thickness on the surface of the developing roller <NUM>. The developing bias voltage may be applied to the developing roller <NUM>. The toner transported to the development nip when the developing roller <NUM> is rotated is moved and attached to the electrostatic latent image formed on the surface of the photosensitive drum <NUM> by the developing bias voltage, and thus a visible toner image may be formed on the surface of the photosensitive drum <NUM>. The print medium P taken out from the loading tray <NUM> by a pickup roller <NUM> may be transported to the transfer nip where the transfer roller <NUM> and the photosensitive drum <NUM> face each other, by a feed roller <NUM>. When the transfer bias voltage is applied to the transfer roller <NUM>, the toner image may be transferred to the print medium P by the electrostatic attraction. The toner image transferred to the print medium P may receive heat and pressure from the fuser <NUM> and may be fused on the print medium P, thereby completing printing. The print medium P is discharged by a discharge roller <NUM>. The toner remaining on the surface of the photosensitive drum <NUM> without being transferred to the print medium P may be removed by the cleaning member <NUM>.

According to the image forming apparatus <NUM> of the current example, the development cartridge <NUM> may include the toner refilling portion <NUM> such that the toner may be refilled in the development cartridge <NUM> while the development cartridge <NUM> is mounted on the main body <NUM> without detaching the development cartridge <NUM> from the main body <NUM>. The toner refilling portion <NUM> may be integrated with the development cartridge <NUM> to be attached to or detached from the main body <NUM> together with the development cartridge <NUM>.

<FIG> is a diagram for describing an operation of the image forming apparatus <NUM> estimating a toner remaining rate, according to an example. <FIG> is a diagram showing equations for the image forming apparatus <NUM> to estimate a toner remaining rate, according to an example.

Referring to <FIG> and <FIG>, a controller <NUM> of the image forming apparatus <NUM> may be connected to the development cartridge <NUM> and a sensor <NUM> to estimate a toner remaining rate of the development cartridge <NUM> according to the equations of <FIG> for estimating a toner remaining rate.

Referring to Equation ① of <FIG> for estimating a toner remaining rate, the estimated toner remaining rate is set to have a value equal to or smaller than <NUM>. When the estimated toner remaining rate is <NUM>, the toner remaining rate is <NUM>%, which denote that the toner is completely filled in the development cartridge <NUM>. In Equation ①, a 'consumption amount' may be calculated by counting pixels or dots, based on image data used in an image forming job. In Equation ①, the 'consumption amount' cumulatively increases the more the user uses the image forming apparatus <NUM>, and a 'consumption amount accumulated at a refill time' is a consumption amount calculated immediately before toner refill, and thus 'consumption amount - consumption amount accumulated at the refill time' after the toner refill has a value of <NUM>. A 'target consumption amount' denotes a consumption amount corresponding to an expected life when the toner is completely filled in the development cartridge <NUM>. A 'correction value' is a value determined according to toner refill capacity after the toner refill, maximum filling capacity of the development cartridge <NUM>, and the toner remaining rate of the development cartridge <NUM> calculated immediately before the toner refill, for example, based on accumulation, for a calculation, of image data used in performing at least one image forming job until the toner refill. Here, the toner refill capacity after the toner refill may be filling capacity of the toner refill cartridge <NUM>. The maximum filling capacity of the development cartridge <NUM> or the target consumption amount corresponding to the expected life of the development cartridge <NUM> may be stored in a memory (not shown) in the development cartridge <NUM>. The filling capacity of the toner refill cartridge <NUM> or the toner refill capacity corresponding to the expected life of the toner refill cartridge <NUM> may be stored in a memory (not shown) in the toner refill cartridge <NUM> and transmitted to the controller <NUM> via the development cartridge <NUM>.

Referring to Equation (<NUM>), the 'correction value' may be a value obtained by subtracting an 'adjusted toner remaining rate based on toner remaining rate calculated immediately before refill' from a ratio of free capacity for further filling the toner despite toner refill capacity to the maximum filling capacity of the development cartridge <NUM>, i.e., a 'free capacity ratio after refill'. The 'adjusted toner remaining rate based on toner remaining rate calculated immediately before refill' indicates adjustment to a suitable value based on whether the 'toner remaining rate calculated immediately before refill' has a negative value because the 'toner remaining rate calculated immediately before refill' may have a negative value. A toner remaining rate calculated immediately before the toner refill may be calculated based on a toner consumption rate obtained by dividing the consumption amount of the toner calculated by counting pixels or dots based on image data used in an image forming job immediately before the toner refill by the consumption amount corresponding to the expected life when the toner is completely filled in the development cartridge <NUM>. Additional descriptions thereof will be provided later with reference to <FIG>. The 'correction value' may indicate that, when the development cartridge <NUM> is not completely filled because the toner refill capacity is smaller than the maximum filling capacity of the development cartridge <NUM>, the ratio of the free capacity for further filling the toner is subtracted from the toner remaining rate while toner capacity remaining in the development cartridge <NUM> immediately before the toner refill is added to the toner remaining rate.

Referring to Equation (<NUM>), the 'free capacity ratio after refill' is obtained by subtracting the rate of the toner refill capacity after toner refill to the maximum filling capacity of the development cartridge <NUM>, i.e., a 'filling ratio after refill', from <NUM>.

When Equation ① is substituted by Equations ② and ③, Equation ④ for estimating a toner remaining rate may be obtained. In other words, Equation ④ is an equation corresponding to a modified form of Equation ①. Referring to Equation ④, the toner remaining rate of the development cartridge <NUM> according to the toner refill may be estimated by subtracting a value of term corresponding to the toner consumption rate from a value obtained by adding the toner filling ratio of the development cartridge <NUM> after toner refill, i.e., the 'filling ratio after refill' and the 'adjusted toner remaining rate based on the toner remaining rate calculated immediately before toner refill'. Since the 'consumption amount - consumption amount accumulated at refill time' after toner refill has a value of <NUM>, the value of term corresponding to the toner consumption rate is <NUM>. Accordingly, the toner remaining rate of the development cartridge <NUM> according to toner refill may be estimated based on the toner filling ratio of the development cartridge <NUM> after toner refill and the adjusted toner remaining rate based on the toner remaining rate calculated immediately before toner refill. The toner filling ratio of the development cartridge <NUM> after toner refill and the adjusted toner remaining rate based on the toner remaining rate calculated immediately before toner refill may be a value determined each time of toner refill and maintained until next toner refill.

Meanwhile, the toner refill may be performed when the toner refill cartridge <NUM> for refilling the toner by being connected to the development cartridge <NUM> forming the toner image by supplying the toner to the electrostatic latent image formed on the photoconductor is combined to the development cartridge <NUM> through the communicating portion <NUM> formed on the outer surface of the main body <NUM> where the development cartridge <NUM> is mounted. According to an example, the toner refill may be performed when the development cartridge <NUM> is replaced.

Referring back to <FIG> and <FIG>, the controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM> according to toner refill, based on the toner filling ratio of the development cartridge <NUM> after toner refill and the adjusted toner remaining rate based on the toner remaining rate calculated immediately before toner refill, according to a detection result of the sensor <NUM>.

The sensor <NUM> may detect a remaining toner amount of the development cartridge <NUM>. The sensor <NUM> may detect whether the remaining toner amount of the development cartridge <NUM> is smaller or greater than a certain criterion. The sensor <NUM> may detect whether the remaining toner amount is greater or smaller than the certain criterion or whether there is remaining toner. For example, the sensor <NUM> may detect the remaining toner amount by detecting the weight of toner accommodated in the development cartridge <NUM> or detect toner exhaustion by using an optical sensor or the like. The sensor <NUM> may detect the remaining toner amount of the development cartridge <NUM> continuously, after a certain period, or when a certain event occurs. Because the sensor <NUM> may be connected to the development cartridge <NUM> to detect the remaining toner amount of the development cartridge <NUM>, the sensor <NUM> may also be used to detect replacement of the development cartridge <NUM>. For example, the controller <NUM> may determine that the development cartridge <NUM> is replaced when the sensor <NUM> detects a change in the weight of toner accommodated in the development cartridge <NUM> without the toner refill cartridge <NUM> being combined with the image forming apparatus <NUM>, when the sensor <NUM> detects that contact of the development cartridge <NUM> connected to the sensor <NUM> has been broken, or when the sensor <NUM> is also replaced together with the development cartridge <NUM>.

The controller <NUM> may determine whether to preform toner refill and a detailed situation where the toner refill is performed, according to a detection result of the sensor <NUM>. Hereinafter, the estimation of the toner remaining rate of the controller <NUM> in the detailed situation where the toner refill is performed will be described.

When the development cartridge <NUM> is replaced by a new development cartridge, the controller <NUM> may estimate a toner remaining rate of the new development cartridge, based on an initial toner filling ratio of the new development cartridge that is a ratio of actual filled volume of the new development cartridge to maximum filling capacity of the new development cartridge, and the adjusted toner remaining rate having a value of <NUM>.

When the toner is refilled by the toner refill cartridge <NUM> when the remaining toner amount detected from the sensor <NUM> is smaller than or equal to a certain criterion, the controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM>, based on a toner refilling ratio of the development cartridge <NUM> that is a ratio of actual filled volume of the toner refill cartridge <NUM> to maximum filling capacity of the development cartridge <NUM>, and the adjusted toner remaining rate having a value of <NUM>. The controller <NUM> may determine that the toner is exhausted when the remaining toner amount detected from the sensor <NUM> is smaller than or equal to the certain criterion. Here, the certain criterion is a toner amount corresponding to a certain threshold point at which the toner is assumed to be exhausted, and may be a value set by the user.

When the toner is refilled by the toner refill cartridge <NUM> when the remaining toner amount detected by the sensor <NUM> is greater than the certain criterion, the controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM>, based on the toner refilling ratio of the development cartridge <NUM> that is the ratio of the actual filled volume of the toner refill cartridge to the maximum filling capacity of the development cartridge <NUM>, and the adjusted toner remaining rate adjusted based on whether the toner remaining rate calculated immediately before toner refill is a negative value. The controller <NUM> may set the adjusted toner remaining rate to a value of <NUM> when the toner remaining rate calculated immediately before toner refill is a negative value, and may set the adjusted toner remaining rate to the toner remaining rate calculated immediately before toner refill when the toner remaining rate calculated immediately before toner refill is not a negative value. The controller <NUM> may determine that the toner is not exhausted when the remaining toner amount detected by the sensor <NUM> is greater than the certain criterion.

The controller <NUM> controls overall operations of the image forming apparatus <NUM> and may include at least one processor, such as a central processing unit (CPU). The controller <NUM> may control other components included in the image forming apparatus <NUM>.

Meanwhile, the image forming apparatus <NUM> may display information, such as a state of the image forming apparatus <NUM>, or the like, or receive a user input from the user through a user interface device (not shown). The user interface device may be in a form of a touch screen. For example, the controller <NUM> may control the user interface device to display, to the user, a result of estimating the toner remaining rate of the development cartridge <NUM> of the image forming apparatus <NUM>.

<FIG> is a flowchart of a method of estimating a toner remaining rate, according to an example.

The image forming apparatus <NUM> or the controller <NUM> may detect, by using the sensor <NUM>, the remaining toner amount of the development cartridge <NUM> mounted on the main body <NUM> and forming the toner image by supplying the toner to the electrostatic latent image formed on the photoconductor.

The image forming apparatus <NUM> or the controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM> according to toner refill, based on the tonner filling ratio of the development cartridge after toner refill and the adjusted toner remaining rate based on the toner remaining rate calculated immediately before toner refill, according to a detection result of the sensor <NUM>.

Hereinafter, a method by which the image forming apparatus <NUM> or the controller <NUM> estimates the toner remaining rate in a detailed situation where toner refill is performed will be described.

In operation <NUM>, the image forming apparatus <NUM> or controller <NUM> may detect toner refill. For example, the image forming apparatus <NUM> or controller <NUM> may detect that the toner refill is performed when the development cartridge <NUM> is replaced or when the remaining toner amount of the development cartridge <NUM> is increased as the toner refill cartridge <NUM> is combined to the development cartridge <NUM> through the communicating portion <NUM> formed on the outer surface of the main body <NUM> where the development cartridge <NUM> is mounted.

In operation <NUM>, the image forming apparatus <NUM> or controller <NUM> may determine whether the development cartridge <NUM> is replaced to the new development cartridge.

When the development cartridge <NUM> is replaced to the new development cartridge, in operation <NUM>, the image forming apparatus <NUM> or controller <NUM> may estimate the toner remaining rate of the new development cartridge, based on the initial toner filling ratio of the new development cartridge that is the ratio of the actual filled volume of the new development cartridge to the maximum filling capacity of the new development cartridge, and the adjusted toner remaining rate having a value of <NUM>. Here, the equations of <FIG> for estimating a toner remaining rate may be used.

When the development cartridge <NUM> is not replaced, in operation <NUM>, the image forming apparatus <NUM> or controller <NUM> may determine whether the toner of the development cartridge <NUM> is exhausted. For example, the image forming apparatus <NUM> or controller <NUM> may determine whether the toner of the development cartridge <NUM> is exhausted by determining whether the remaining toner amount of the development cartridge <NUM> detected by the sensor <NUM> is greater than the certain criterion.

When the toner of the development cartridge <NUM> is exhausted, in operation <NUM>, when the toner is refilled by the toner refill cartridge <NUM>, the image forming apparatus <NUM> or controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM>, based on the toner refilling ratio of the development cartridge <NUM> that is the ratio of the actual filled volume of the toner refill cartridge <NUM> to the maximum filling capacity of the development cartridge <NUM>, and the adjusted toner remaining rate having a value of <NUM>. Here, the equations of <FIG> for estimating a toner remaining rate may be used. The image forming apparatus <NUM> or controller <NUM> may determine that the toner is exhausted when the remaining toner amount detected by the sensor <NUM> is smaller than or equal to the certain criterion.

When the development cartridge <NUM> is not exhausted, in operation <NUM>, the image forming apparatus <NUM> or controller <NUM> may determine whether the toner remaining rate calculated immediately before toner refill is a negative value. The image forming apparatus <NUM> or controller <NUM> may determine that the toner is not exhausted when the remaining toner amount detected by the sensor is greater than the certain criterion.

When the toner remaining rate calculated immediately before toner refill is a negative value, in operation <NUM>, when the toner is refilled by the toner refill cartridge <NUM>, the image forming apparatus <NUM> or controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM>, based on the toner refilling ratio of the development cartridge <NUM> that is the ratio of the actual filled volume of the toner refill cartridge to the maximum filling capacity of the development cartridge <NUM>, and the adjusted toner remaining rate having a value of <NUM>. Here, the equations of <FIG> for estimating a toner remaining rate may be used.

When the toner remaining rate calculated immediately before toner refill is not a negative value, in operation <NUM>, when the toner is refilled by the toner refill cartridge <NUM>, the image forming apparatus <NUM> or controller <NUM> may estimate the toner remaining rate of the development cartridge <NUM>, based on the toner refilling ratio of the development cartridge <NUM> that is the ratio of the actual filled volume of the toner refill cartridge <NUM> to the maximum filling capacity of the development cartridge <NUM>, and the adjusted toner remaining rate having a value of the toner remaining rate calculated immediately before toner refill. Here, the equations of <FIG> for estimating a toner remaining rate may be used.

<FIG> is a flowchart for describing a method of estimating a toner remaining method, according to an example, with an example. Details that overlap those of <FIG> will not be provided again.

In <FIG>, a case where the development cartridge <NUM> is replaced is described with an example in which the actual filled volume of the new development cartridge is equal to the maximum filling capacity of the new development cartridge, i.e., the actual filled volume of the new development cartridge is <NUM>%.

A case of toner refill using the toner refill cartridge <NUM> is described with an example in which the ratio of the actual filled volume of the toner refill cartridge <NUM> to the maximum filling capacity of the development cartridge <NUM> is <NUM>, and <NUM>% of the development cartridge <NUM> is refilled by using the toner refill cartridge <NUM>.

According to such an example, when the development cartridge <NUM> is replaced to the new development cartridge in operation <NUM>, in operation <NUM>, since the initial toner filling ratio of the new development cartridge is <NUM>, the image forming apparatus <NUM> or controller <NUM> sets the 'free capacity ratio after refill' to <NUM> and the 'adjusted toner remaining rate' to <NUM>. When each numerical value substitutes for the equations of <FIG> for estimating a toner remaining rate, the 'correction value' becomes <NUM> and the 'consumption amount - consumption amount accumulated at refill time' after toner refill has a value of <NUM> according to Equation (<NUM>), and thus the 'estimated toner remaining rate' becomes <NUM> according to Equation ①. Since the actual filled volume of the new development cartridge is <NUM>%, the 'estimated toner remaining rate' is identified to be <NUM> corresponding to <NUM>%.

When the toner of the development cartridge <NUM> is exhausted in operation <NUM>, in operation <NUM>, since the toner refilling ratio of the development cartridge <NUM> refilled by the toner refill cartridge <NUM> is <NUM>, the image forming apparatus <NUM> or controller <NUM> sets the 'free capacity ratio after refill' to <NUM> and the 'adjusted toner remaining rate' to <NUM>. When each numerical value substitutes for the equations of <FIG> for estimating a toner remaining rate, the 'correction value' becomes <NUM> and the 'consumption amount - consumption amount accumulated at refill time' after toner refill has a value of <NUM> according to Equation (<NUM>), and thus the 'estimated toner remaining rate' becomes <NUM> according to Equation ①. Since <NUM>% of the development cartridge <NUM> is refilled by the toner refill cartridge <NUM>, the 'estimated toner remaining rate' is identified to be <NUM> corresponding to <NUM>%.

When the toner of the development cartridge <NUM> is not exhausted and the toner remaining rate calculated immediately before toner refill is a negative value in operation <NUM>, in operation <NUM>, since the toner refilling ratio of the development cartridge <NUM> refilled by the toner refill cartridge <NUM> is <NUM>, the image forming apparatus <NUM> or controller <NUM> may set the 'free capacity ratio after refill' to <NUM> and the 'adjusted toner remaining rate' to <NUM>. When each numerical value substitutes for the equations of <FIG> for estimating a toner remaining rate, the 'correction value' becomes <NUM> and the 'consumption amount - consumption amount accumulated at refill time' after toner refill has a value of <NUM> according to Equation (<NUM>), and thus the 'estimated toner remaining rate' becomes <NUM> according to Equation ①. Since <NUM>% of the development cartridge <NUM> is refilled by the toner refill cartridge <NUM>, the 'estimated toner remaining rate' is identified to be <NUM> corresponding to <NUM>%. In other words, when the toner remaining rate calculated immediately before toner refill is a negative value despite the toner is not exhausted, the 'adjusted toner remaining rate' is set to be <NUM> such that the 'estimated toner remaining rate' that is the toner refilling ratio of the development cartridge <NUM> does not decrease down to less than <NUM>.

When the toner of the development cartridge <NUM> is not exhausted and the toner remaining rate calculated immediately before toner refill is not a negative value, in operation <NUM>, since the toner refilling ratio of the development cartridge <NUM> refilled by the toner refill cartridge <NUM> is <NUM>, the image forming apparatus <NUM> or controller <NUM> sets the 'free capacity ratio after refill' to <NUM> and the 'adjusted toner remaining rate' to the toner remaining rate calculated immediately before toner refill. When each numerical value substitutes for the equations of <FIG> for estimating a toner remaining rate, the 'correction value' becomes '<NUM> - toner remaining rate calculated immediately before toner refill' and the 'consumption amount - consumption amount accumulated at refill time' after toner refill has a value of <NUM> according to Equation (<NUM>), and thus the 'estimated toner remaining rate' becomes '<NUM> + toner remaining rate calculated immediately before toner refill' according to Equation ①. In other words, when the toner is not exhausted and the toner remaining rate calculated immediately before toner refill is not a negative value, the 'adjusted toner remaining rate' is set to the toner remaining rate calculated immediately before the toner refill such that the toner remaining rate equal to the toner capacity left in the development cartridge <NUM> immediately before toner refill is further reflected to the 'estimated toner remaining rate'.

<FIG> illustrates data results showing that the equations of <FIG> for estimating a toner remaining rate are valid when toner refill is performed in a toner exhaustion state in the example of <FIG>.

Referring to <FIG>, Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill and the actual toner remaining rate are the same and are <NUM>, Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill is greater than the actual toner remaining rate and thus is greater than <NUM>, and Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill is smaller than the actual toner remaining rate and thus is smaller than <NUM>.

Since the toner refill is performed in the toner exhaustion state in <FIG>, it is appropriate that the toner remaining rate calculated immediately before toner refill is adjusted to have a value of <NUM>. Since the development cartridge <NUM> is refilled to <NUM>% by using the toner refill cartridge <NUM> while the toner is exhausted in terms of the user who refilled the toner in the image forming apparatus <NUM>, the user may expect the estimated toner remaining rate to be <NUM>% corresponding to a value of <NUM>.

Referring to the data results of <FIG>, in all cases, the actual toner remaining rates are <NUM> immediately before toner refill, the toner remaining rates calculated immediately before toner refill are all adjusted to <NUM> regardless of values thereof, and the 'consumption amount - consumption amount accumulated at refill time' after refill is <NUM>, and thus the estimated toner remaining rate is <NUM>% corresponding to a value of <NUM>.

<FIG> illustrates results data showing that the equations of <FIG> for estimating a toner remaining rate are valid when toner refill is performed in a state in which toner is not exhausted in the example of <FIG>.

Referring to <FIG>, Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill and the actual toner remaining rate are the same and are greater than <NUM>, Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill is greater than the actual toner remaining rate, and Case <NUM> denotes a case in which the toner remaining rate calculated immediately before toner refill is smaller than the actual toner remaining rate and thus is smaller than <NUM>.

Since the toner refill is performed not in the toner exhaustion state in <FIG>, it is determined that the actual toner remaining rate immediately before toner refill is greater than <NUM>. Since <NUM>% of the development cartridge <NUM> is further refilled by using the toner refill cartridge <NUM> before the toner is exhausted in terms of the user who refilled the toner in the image forming apparatus <NUM>, the user may expect the estimated toner remaining rate to be at least <NUM>% corresponding to a value of at least <NUM>.

Referring to the data results of <FIG>, in all cases, the actual toner remaining rates immediately before toner refill are greater than <NUM> and the 'consumption amount - consumption amount accumulated at refill time' after refill time is <NUM>. In Case <NUM> in which the toner remaining rate calculated immediately before toner refill is a negative value corresponding to -<NUM>%, the toner remaining rate calculated immediately before toner refill is adjusted to <NUM>, and in Cases <NUM> and <NUM> in which the toner remaining rate calculated immediately before toner refill is not a negative value, the toner remaining rate calculated immediately before toner refill may be the adjusted toner remaining rate. In Cases <NUM> and <NUM>, the estimated toner remaining rate is <NUM>% (<NUM>% + <NUM>%), and in Case <NUM>, the estimated toner remaining rate is <NUM>%. In all cases, the estimated toner remaining rate after toner refill is at least <NUM>% corresponding to a value of at least <NUM>.

Claim 1:
An image forming apparatus (<NUM>) comprising:
a body (<NUM>) on which a development cartridge (<NUM>) is mountable to form a toner image by supplying toner in the development cartridge (<NUM>) to an electrostatic latent image formed;
a communicating portion (<NUM>) provided on an outer surface of the body (<NUM>) to be coupled with a toner refill cartridge (<NUM>) to form a connection with the development cartridge (<NUM>) to perform a toner refill of the toner in the development cartridge (<NUM>) through the connection with the development cartridge (<NUM>);
a sensor (<NUM>) to detect a remaining toner amount remaining in the development cartridge (<NUM>); and
a controller (<NUM>) to estimate, based on the sensor (<NUM>) detecting the remaining toner amount, an estimated toner remaining rate of the development cartridge (<NUM>), which is an estimated rate of the toner remaining in the development cartridge (<NUM>) based on toner consumption, according to the toner refill, based on
a toner filling ratio of the development cartridge (<NUM>), which is a ratio of a volume of the toner of the development cartridge (<NUM>) after the toner refill to a toner filling capacity of the development cartridge (<NUM>), and
an adjusted toner remaining rate that is an adjusted value of a toner remaining rate calculated based on image data used in performing of at least one image forming job until the toner refill.