JP2004184891A - Image forming device and calculation method of used toner amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device and a calculation method of the used toner, which can precisely calculate the amount of the used toner to form a toner image. <P>SOLUTION: When the total number Cp of the printed sheets is in a first segment (0≤Cp≤Cp1), the offset Tod is set to a value Tod1 matching the first segment. Also, when the Cp is in a second segment (Cp1<Cp≤Cp2), the offset Tod is set to the value Tod2 matching the second segment. Further, when the Cp is in a third segment (Cp2<Cp), the offset Tod is set to the value Tod2 matching the third segment. Since the offset Tod is changed and set suitable by correlating the change over aging of the toner characteristics with the operation of the device and the past actual use of the toner, the offset Tod can be set to a value matching the toner characteristics even if there are changes in them. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for determining the amount of toner consumed when forming a toner image in an image forming apparatus that forms a toner image in predetermined units.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a printer, a copying machine, and a facsimile apparatus that forms an image using toner, it is necessary to grasp the amount of toner consumption or the amount of toner remaining for maintenance such as toner supply. Accordingly, the applicant of the present application has proposed a toner consumption detecting method capable of accurately obtaining the amount of toner consumed when forming a toner image in a predetermined unit (for example, one page unit or job unit) with a simple configuration. And an apparatus have already been disclosed (see Patent Document 1). In this detection method and apparatus, in view of the fact that the relationship between the value of a print dot and the amount of toner consumed is non-linear and changes depending on the state of a print dot adjacent to the print dot, the print dot row is divided into two isolated dots. The toner is divided into three patterns of dots and intermediate value dots, the number of the formed dots is counted for each of these patterns, and a toner constituting a toner image based on the counted value (corresponding to “image constituting toner” of the present invention) Is seeking the total amount.
[0003]
Further, an offset value (unique value) is added to the total amount in consideration of the presence of toner consumed separately from the image forming toner when forming a toner image, and this value is used as the toner consumption amount. That is, as is well known in the related art, when a white image, that is, an image forming operation in which no print dots are formed, a so-called fog occurs and a small amount of toner is consumed. By doing so, the accuracy of calculating the toner consumption is improved.
[0004]
[Patent Document 1]
JP-A-2002-174929 (pages 3 and 4)
[0005]
[Problems to be solved by the invention]
In such an image forming apparatus, it is desirable that the properties of the toner used are constant in order to stably form the toner image. However, in an actual apparatus, it is known that the image density of the toner image may gradually change while the formation of the toner image is repeated. As can be seen from this fact, the property of the toner is not always constant. Instead, they may change over time. The appearance of this change varies depending on the device configuration or the toner used. For example, in this type of image forming apparatus, there is a phenomenon that selective development, that is, a toner in which particles having various particle diameters are mixed has selectivity in the particle diameter of the toner consumed for development. The particle size distribution of the toner is gradually changed. When the properties of the toner change over time in this way, it goes without saying that the quality of the formed toner image is affected, but the above-described offset value also changes according to the change over time.
[0006]
It is conventionally known that in this type of image forming apparatus, image quality such as image density can be controlled by changing image forming conditions including various elements such as a bias potential applied to each section of the apparatus. Further, the image density of the toner image may be different due to individual differences of the apparatuses, aging, and changes in the surrounding environment such as temperature and humidity. Therefore, the image density is controlled by adjusting the image forming conditions which affect the image density among the above elements, and the fog amount is changed by the change setting of the image forming conditions. Will change according to the change setting of.
[0007]
When the offset value changes in this manner, in the conventional image forming apparatus in which the offset value is fixedly set, a discrepancy occurs between the calculated toner consumption amount and the actual value, and an accurate timing May make it difficult to supply toner. Therefore, there is a need to establish a technology capable of obtaining the toner consumption amount with higher accuracy regardless of the temporal change of the offset value.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and provides an image forming apparatus and a method of calculating a toner consumption amount, which can accurately determine a toner amount in a predetermined unit consumed by forming a toner image. The purpose is to do.
[0009]
[Means for Solving the Problems]
The present invention relates to an image forming apparatus that forms a toner image in a predetermined unit and calculates a toner consumption amount consumed when the toner image is formed, and a method of calculating a toner consumption amount, and forms a toner image. The toner consumption is obtained by adding, as an offset value, the amount of toner consumed separately from the image forming toner when forming the toner image to the total amount of the image forming toner. In order to achieve the above object, according to the present invention, the offset value is appropriately changed and set in accordance with the change over time in the properties of the toner used and the image forming conditions. Specifically, (1) the offset value is changed and set in accordance with the operation status of the apparatus, (2) the offset value is changed and set in accordance with the usage history of the toner, and (3) the offset value is set in the toner image. The setting is changed according to image forming conditions for forming.
[0010]
Although the properties of the used toner change with time as described above, it can be obtained by examining the operation status of the apparatus and the usage history of the toner. Therefore, in the present invention, the offset value is appropriately changed and set by associating the time-dependent change in the properties of the toner with the operation state of the apparatus and the usage history of the toner. Therefore, even if the properties of the toner change, the offset value is set in accordance with the change, so that the toner consumption can be accurately obtained.
[0011]
Here, the values directly or indirectly indicating the operation status of the apparatus and the usage history of the toner include, for example, the cumulative value of the number of printed sheets (total number of printed sheets), the cumulative number of rotations of the image bearing member carrying the toner image, and the developing speed. The cumulative number of rotations of a toner carrier that rotates while carrying toner in a developing unit such as a container or a developing cartridge, the cumulative number of rotations of an intermediate transfer medium such as an intermediate transfer drum or an intermediate transfer belt on which a toner image is temporarily transferred, It includes an integrated value obtained by integrating the toner consumption obtained in a predetermined unit (that is, the total amount of toner consumption), the remaining amount of toner remaining in the developing device, and the like. The offset value may be changed and set based on one of these values (accumulated value, accumulated rotation speed, etc.), or the offset value may be changed and set based on a plurality of values. As the latter example, for example, the cumulative number of rotations of the image carrier and the cumulative number of rotations of the toner carrier can be combined, or the integrated value of toner consumption and the remaining amount of toner can be combined.
[0012]
Also, when the image forming conditions are changed, the amount of toner consumed separately from the image forming toner when forming the toner image as described above changes. Since the setting is changed according to the forming condition, the offset value corresponding to the image forming condition is always set, and the toner consumption can be accurately obtained.
[0013]
The "predetermined unit" in the present invention means a unit for calculating the toner consumption, and includes, for example, a unit of one page of a toner image or a unit of a job.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus forms a full-color image by superimposing four color toners of yellow (Y), cyan (C), magenta (M), and black (K), or a monochrome image using only black (K) toner. This is an image forming apparatus for forming an image. In this image forming apparatus, when a print command is given to the main controller 11 from an external device such as a host computer, the CPU 111 of the main controller 11 converts the job data into job data in a format suitable for an operation instruction of the engine EG. Then, the engine controller 12 controls each unit of the engine unit EG according to the job data from the main controller 11, and responds to a print command on a sheet (recording medium) S such as a transfer sheet, a copy sheet or an OHP sheet in a job unit. Form an image.
[0015]
In this engine EG, the photoconductor 2 is provided rotatably in the arrow direction D1 in FIG. A charging unit 3, a rotary developing unit 4, and a cleaning unit 5 for charging the surface of the photoconductor 2 to a predetermined surface potential are arranged around the photoconductor 2 along the rotation direction D1. The charging unit 3 is applied with a charging bias from the charging bias generation unit 121 and uniformly charges the outer peripheral surface of the photoconductor 2.
[0016]
Then, the light beam L is emitted from the exposure unit 6 toward the outer peripheral surface of the photoconductor 2 charged by the charging unit 3. As shown in FIG. 2, the exposure unit 6 is electrically connected to an exposure power control unit 123, and based on a modulation signal corresponding to an image signal given via an image signal switching unit 122, the exposure power control unit Reference numeral 123 controls each part of the exposure unit 6, and exposes the photoconductor 2 with the light beam L to form an electrostatic latent image on the photoconductor 2 corresponding to an image signal.
[0017]
For example, based on a command from the CPU 124 of the engine controller 12, when the image signal switching unit 122 is electrically connected to the pattern creation module 125 (an image forming condition adjustment operation described later), the image output from the pattern creation module 125. A modulation signal corresponding to the pattern is provided to the exposure power control unit 123, and an electrostatic latent image is formed. On the other hand, when the image signal switching unit 122 is electrically connected to the CPU 111 of the main controller 11 (a normal image forming operation to be described later), the image signal switching unit 122 includes a print command provided from an external device such as a host computer via the interface 112. The modulation signal generated by the modulation signal generator 210 based on the image data to be output is provided to the exposure power controller 123. Then, the photoconductor 2 is exposed by the light beam L based on the modulation signal, and an electrostatic latent image corresponding to the image signal is formed on the photoconductor 2. As a modulation method, various pulse modulation methods such as pulse width modulation (PWM) and pulse amplitude modulation (PAM) can be adopted.
[0018]
The electrostatic latent image thus formed is visualized by the rotary developing unit 4. That is, in this embodiment, as the developing unit 4, a developing unit 4K for black, a developing unit 4C for cyan, a developing unit 4M for magenta, and a developing unit 4Y for yellow are provided rotatably about the axis. . The developing units 4K, 4C, 4M, and 4Y are rotationally positioned, and the developing rollers 40K, 40C, 40M, and 40Y of the developing units 4K, 4C, 4M, and 4Y are selectively provided with respect to the photosensitive member 2. The toner of the selected color is supplied to the surface of the photoreceptor 2 from the developing roller by the developing roller 126 being applied with a developing bias by the developing bias generating unit 126. Thus, the electrostatic latent image on the photoconductor 2 is visualized in the selected toner color. Thus, in this embodiment, the photoconductor 2 functions as the “image carrier” of the present invention.
[0019]
The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt (intermediate transfer medium) 71 of the transfer unit 7 in the primary transfer area TR1. Further, a cleaning unit 5 is disposed at a position in the circumferential direction (rotational direction D1 in FIG. 1) from the primary transfer area TR1, and the toner remaining on the outer peripheral surface of the photoconductor 2 after the primary transfer. Is scraped off by the cleaning blade 51. Further, the surface potential of the photoconductor 2 is reset by a charge removing unit (not shown) as necessary.
[0020]
The transfer unit 7 corresponds to a “transfer unit” of the present invention, and includes an intermediate transfer belt 71 wrapped around a plurality of rollers, and a driving unit (not shown) for driving the intermediate transfer belt 71 to rotate. ing. When the color image is transferred to the sheet S, the color image is formed by superimposing the toner images of each color formed on the photoreceptor 2 on the intermediate transfer belt 71, and a predetermined secondary transfer area TR2 is formed. , The color image is secondarily transferred onto the sheet S taken out of the cassette 8. Further, the sheet S on which the color image is formed is conveyed via the fixing unit 9 to a discharge tray provided on the upper surface of the apparatus main body. After the secondary transfer, the toner remaining on the intermediate transfer belt 71 is removed from the intermediate transfer belt 71 by a cleaning unit (not shown).
[0021]
Further, a patch sensor PS is disposed to face the surface of the intermediate transfer belt 71, and when performing an image forming condition adjusting operation described later, the optical density of the patch image formed on the outer peripheral surface of the intermediate transfer belt 71 is determined. Measure. In addition to the patch sensor PS, a vertical synchronization sensor 72 is provided. The vertical synchronization sensor 72 is a sensor for detecting the reference position of the intermediate transfer belt 71, and outputs a synchronization signal output in association with the rotation of the intermediate transfer belt 71, that is, a vertical synchronization signal Vsync. Functions as a synchronous sensor. In this apparatus, the operation of each section of the apparatus is controlled based on the vertical synchronization signal Vsync so that the operation timing of each section is aligned and the toner images formed in each color are accurately overlapped. Further, by counting the vertical synchronization signal Vsync, the cumulative number of rotations of the intermediate transfer belt 71 can be obtained.
[0022]
Further, as shown in FIG. 2, the developing units 4K, 4C, 4M, and 4Y are provided with unit-side communication units 41K, 41C, 41M, and 41Y, respectively, and the unit-side communication units 41K, 41C, 41M, and 41Y are provided. Are electrically connected to the memories 42K, 42C, 42M, and 42Y, respectively. The memories 42K, 42C, 42M, and 42Y store various data relating to the production lots, use histories, characteristics of the built-in toner, the remaining amount of the toner, and the like of each of the developing devices 4K, 4C, 4M, and 4Y. Further, the apparatus main body is provided with a main body side communication unit 128 electrically connected to the CPU 124.
[0023]
When the developing rollers 40K, 40C, 40M, and 40Y of the developing devices 4K, 4C, 4M, and 4Y are selectively positioned opposite to the photoconductor 2, the unit-side communication unit of the selected developing device is It is configured to face the main body side communication unit 128 within a predetermined distance, for example, within 10 mm, and can transmit and receive data in a non-contact state with each other by wireless communication such as infrared rays. As a result, the CPU 124 manages various types of information such as detection of mounting of the developing device, detection of a new product, and management of life.
[0024]
In this embodiment, data is transmitted and received in a non-contact manner using electromagnetic means such as wireless communication. However, for example, connectors are provided on the apparatus main body and each of the developing devices 4K, 4C, 4M, and 4Y. When each of the developing devices 4K, 4C, 4M, and 4Y is selectively positioned to face the photoconductor 2, the connector of the apparatus main body is mechanically fitted with the connector of the developing device to transmit and receive data mutually. It may be performed. The memories 42K, 42C, 42M, and 42Y are preferably non-volatile memories that can store data even when the power is off or the developing units 4K, 4C, 4M, and 4Y are removed from the apparatus main body. As the nonvolatile memory, for example, an EEPROM such as a flash memory, a ferroelectric memory (Ferroelectric RAM), or the like can be used.
[0025]
In FIG. 2, an image memory 113 provided in the main controller 11 is for storing image data given via an interface 112 from an external device such as a host computer. Further, the memory 127 provided in the engine controller 12 includes a ROM for storing a control program executed by the CPU 124 and a RAM for temporarily storing a calculation result in the CPU 124, control data for controlling the engine EG, and the like. Become. Further, a dot counter 200 is provided in the main controller 11 of the image forming apparatus.
[0026]
FIG. 3 is a block diagram showing the configuration of the dot counter. FIG. 4 is a diagram for explaining a counting procedure by the dot counter, and shows an example of a tone value of a printing dot. The dot counter 200 determines the type of print dots formed on the photoconductor 2 based on an image signal output from the main controller 11 to the engine controller 12 and counts the number of the print dots. More specifically, the dot counter 200 includes a comparison circuit 201, a determination circuit 202, and three counters 203 to 205.
[0027]
As shown in FIG. 3, an image signal given to the engine controller 12 from the CPU 111 of the main controller 11 is input to the comparison circuit 201. Then, the comparison circuit 201 compares the gradation level of the image signal corresponding to each print dot with predetermined thresholds L1 and L2. The threshold value L1 is set to a value close to the gradation 0 (that is, 1/63 of the maximum gradation MAX), and the threshold value L2 is set to a value close to the maximum gradation MAX (that is, 48 / MAX of the solid image). 63). Then, the comparison circuit 201 outputs the value “11” to the determination circuit 202 when the gradation level is equal to or larger than the threshold L2, and outputs the value “00” when the gradation level is smaller than the threshold L1. In response to this, the determination circuit 202 determines the continuous state of each print dot, that is, whether or not there is a dot adjacent to the target print dot, and outputs a signal corresponding to the result to the subsequent counters 203 to 205. Output to
[0028]
The operation of the determination circuit 202 will be described in more detail. The discriminating circuit 202 outputs a signal “1” to the counter 203 every time an output signal “11” indicating that a print dot having a gradation level equal to or larger than the threshold value L2 is output from the comparing circuit 201. Therefore, the counter 203 accumulates the number C1 of print dots having gradation levels equal to or greater than the threshold L2. In FIG. 4, print dots 1, 2, 3, 6, and 13 correspond, and C1 = 5.
[0029]
In addition, the determination circuit 202 outputs a signal “1” to the counter 204 when three or more print dots having a gradation level equal to or greater than the threshold L2 continue. Therefore, the counter 204 accumulates the number C2 of three or more continuous dots. In FIG. 4, print dots 1 to 3 correspond, and C2 = 1.
[0030]
Further, a signal “1” is output to the counter 205 when there are no dots equal to or larger than the threshold value L1 on the left and right of the target print dot, that is, when the print dot is an isolated dot. Therefore, the number C3 of the isolated dots is accumulated in the counter 205. In FIG. 4, print dots 6 and 13 correspond to isolated dots, and C3 = 2.
[0031]
In this way, each of the counters 203 to 205 accumulates the number C1 of high tone print dots, the number C2 of three or more continuous dots and the number C3 of isolated dots among them, and for example, one color toner These values are stored in the memory 211 each time one image is formed. These values are transmitted from the memory 211 to the CPU 124 of the engine controller 12 at a predetermined timing (for example, when the formation of toner images of four colors is completed or when data is requested from the CPU 124), and stored in the memory 127 as necessary. Then, it is used for calculating the remaining amount of toner described later.
[0032]
In the image forming apparatus configured as described above, when a print command is given from an external device such as a host computer, a normal image forming operation for forming an image corresponding to the print command is executed. Specifically, a print command, which is an image formation request from an external device, and image data corresponding to the content of an image to be formed are input to the main controller 11 via the interface 112. The CPU 111 of the main controller 11 separates the received image data for each toner color, develops the image data into image signals having multiple gradation levels, and converts the image signals through the modulation signal generation unit 210 to the engine controller 12. Output to In response to this, the CPU 124 of the engine controller 12 controls each part of the engine EG to execute the above-described series of image forming operations, whereby a desired image is formed on the sheet S. At this time, the image signal switching unit 122 is connected so that an image signal from the main controller 11 is sent to the exposure power control unit 123 in response to a command from the CPU 124.
[0033]
FIG. 5 is a flowchart illustrating the toner counting operation when the image forming operation is performed. In this image forming apparatus, the CPU 124 of the engine controller 12 executes the toner counting operation shown in FIG. 5 each time an image for one sheet is formed in order to facilitate the management of consumables. Is calculated. That is, in this embodiment, one page is set as the “predetermined unit” of the present invention, and the CPU 124 functions as the “consumption amount calculating unit” and the “toner remaining amount calculating unit” of the present invention. Here, a method for obtaining the toner consumption amount and a method for obtaining the remaining toner amount in the developing device 4Y will be described using the yellow color as an example, but the operation is the same for other toner colors.
[0034]
In the toner counting operation of FIG. 5, first, the count values C1, C2, and C3 of the print dots by the dot counter 200 are obtained (step S1). Then, a value Ts is obtained by multiplying each of these values by a predetermined coefficient (step S2). That is,
Ts = Kx · (K1 · C1 + K2 · C2 + K3 · C3)
It is. Here, Kx, K1, K2, and K3 are weighting coefficients set in advance for each toner color. In this way, the print dots are grouped for each continuous dot number and counted, and each number is multiplied by a weighting coefficient and integrated, thereby forming a toner image by being attached to the photoreceptor 2 as an image carrier. That is, the total amount of the toner to be used, that is, the “image forming toner” of the present invention can be accurately obtained. The method of calculating the amount of toner is described in detail in Patent Document 1 mentioned above, and thus the description thereof is omitted here.
[0035]
Next, the remaining toner amount Tr of the developing device 4Y stored in the memory 127 of the engine controller 12 is read (step S3). Then, a value obtained by subtracting the value Ts obtained above from this value Tr is set as a new toner remaining amount Tr (step S4).
[0036]
Further, it is known that in this type of image forming apparatus, a small amount of toner is consumed even when an image forming operation in which a white image, that is, no print dot is formed, is executed. This is because a part of the incompletely charged toner or the oppositely charged toner moves from the developing device 4Y onto the photoreceptor 2 during the image forming operation, or a part of the toner scatters inside the apparatus. When attached to an image, it is visually recognized as fog.
[0037]
In consideration of the fact that toner is lost separately from the toner constituting the image due to such a phenomenon, the offset value Tod corresponding to the drive time of the developing device is set (step S5). As for the offset value Tod, if the sheet size is constant, the developing device driving time per sheet is generally substantially constant. Therefore, the offset value Tod is predetermined for each sheet size and stored in the memory 127. In this embodiment, the offset value Tod is appropriately changed and set in consideration of the operation state of the apparatus and the usage history of the toner (offset value change setting operation described later in detail).
[0038]
By subtracting the offset value Tod thus obtained from the remaining toner amount Tr obtained in step S4 (step S6), a new remaining toner amount Tr after forming one image is obtained. This value Tr is updated and stored in the memory 127 (step S7).
[0039]
As described above, the sum (Ts + Tod) of the product sum Ts of each dot count value C1 and the like and the weighting coefficient K1 and the like and the offset value Tod (Ts + Tod) is the amount of toner consumed when one sheet of image is formed. Become. Then, the amount of toner consumed every time one image is formed is calculated, and subtracted from the amount of toner remaining immediately before, so that the remaining amount of toner Tr in the developing device 4Y at the current time (at the end of image formation) is calculated. Can be requested.
[0040]
In this embodiment, the remaining toner amount in the developing device at each time is obtained by subtracting the toner consumption amount for each image from the initial toner storage amount of each developing device. Needless to say, this is in principle equivalent to calculating the total amount of consumed toner by integrating the toner consumption for each image. As described above, in this embodiment, the amount of toner consumed when one sheet of image is formed corresponds to the “toner consumption amount” of the present invention, and the value obtained by integrating this toner amount is the value of the present invention. It corresponds to "integrated value".
[0041]
Here, in the developing device 4Y or the like which is configured to be detachable from the apparatus main body, before each developing device is detached from the apparatus main body, the toner remaining amount Tr in the developing device determined above is stored in the memory 42Y. It is preferable that the information is stored in the storage device. Then, when the developing device is mounted on the apparatus main body, the remaining amount of toner in the developing device stored in the memory 42Y or the like is read and used as an initial value of the remaining toner amount Tr in the toner counting operation. The life of the developing device can be easily managed. Of course, in a new developing device, the loaded amount of toner at the time of shipment of the developing device may be stored.
[0042]
Further, in this embodiment, the toner end of the developing device 4Y is determined based on the remaining toner amount Tr after image formation. That is, the remaining toner amount Tr obtained as described above is compared with the minimum toner amount Tmin preset for the developing device 4Y (step S8), and the remaining toner amount Tr falls below the minimum toner amount Tmin. If so, it is determined that the toner has run out, and the fact is notified to the main controller 11 (step S9). On the other hand, if the remaining toner amount Tr is equal to or greater than the minimum toner amount Tmin, the toner counting operation is terminated.
[0043]
The minimum toner amount Tmin is the minimum amount of toner required for the developing device 4Y in order to form a good image using the developing device 4Y. That is, if image formation is performed while the toner amount in the developing device is lower than the value Tmin, there is a high possibility that serious image quality deterioration such as insufficient image density or blurring of the image occurs. Thus, as described above, when the toner remaining amount Tr falls below the minimum toner amount Tmin, it is determined that the toner is exhausted, so that it is possible to accurately grasp the replacement time of the developing device 4Y.
[0044]
The operation of the main controller 11 when receiving the notification of the toner end from the engine controller 12 is optional. For example, a message notifying the user of the toner end may be displayed on a display (not shown) to prompt the user to replace the developing device. At this time, the image forming operation may be further continued, or the image forming operation may be prohibited. Further, for example, when the developing device determined to be out of toner is other than the black developing device 4K, only the formation of a monochrome image using black toner may be permitted.
[0045]
Next, the reason for appropriately changing and setting the offset value Tod and the operation thereof (offset value change setting operation) will be described in detail with reference to FIGS.
[0046]
FIG. 6 is a diagram illustrating a change in the particle size distribution of the toner. In a toner used in this type of image forming apparatus, toner particles having various particle diameters are mixed, so that the particle diameter distribution has a certain spread. On the other hand, when an image is formed using a toner having such a particle size distribution, there is known a phenomenon called so-called selective development in which the probability of consumption is different due to the difference in the particle size of the toner.
[0047]
This phenomenon has been experimentally confirmed. FIG. 6A shows how the proportion (volume%) of the small particle size toner having a particle size of 5 μm or less in the total toner in the developing unit changes when image formation is repeatedly performed. It shows an example of the result of actual measurement. FIG. 6B shows the change in the volume average particle size of the toner remaining in the developing device at that time. As shown in FIG. 6A, as the image formation is performed over a long period of time and the amount of toner consumption increases, the ratio of the small particle size toner gradually decreases. The volume average particle size shown gradually increases. From this, it can be understood that toner having various particle diameters is not consumed uniformly by performing image formation, but toner having a small particle diameter is preferentially consumed initially. As described above, as the image formation is repeated and the toner consumption increases, the degree of variation in the particle size of the toner in the developing device, that is, the particle size distribution of the toner also gradually changes.
[0048]
Therefore, when looking at the relationship between the fog amount and the actual toner consumption, a simple linear relationship is not established between the two, and the relationship between the two generally has nonlinearity. This is because, as described above, since the particle size distribution of the toner changes, the toner consumption due to fog, that is, the offset value Tod also changes correspondingly. Therefore, if the offset value Tod is fixed, it is difficult to accurately calculate the toner consumption.
[0049]
As described above, if a deviation occurs between the calculated toner consumption amount and the actual value, the following problem occurs. For example, when the toner end is determined based on the calculated toner consumption, if such a deviation occurs, the timing of replacement of the developing device will be erroneous. That is, even though a sufficient amount of toner still remains, the user discards the developing device, or delays in arranging a new developing device without noticing that the toner is low. . Further, as described later, when adjusting the image forming conditions in accordance with the toner consumption, it is not possible to perform the adjustment at an accurate timing, which causes a problem that the fluctuation of the image density becomes large. Therefore, in this embodiment, the offset value Tod is appropriately changed and set in consideration of the operation state of the apparatus and the usage history of the toner.
[0050]
FIG. 7 is a flowchart showing an offset value change setting operation. In the image forming apparatus according to this embodiment, every time the toner count operation shown in FIG. 5 is executed, the CPU 124 executes the arithmetic processing described below according to a change setting program stored in the memory 127 in advance. The offset value Tod is changed according to the operation state of the image forming apparatus and the usage history of the toner by executing the function, and functions as the “offset value setting unit” of the present invention.
[0051]
First, the total number of printed sheets Cp is read from the memory 127 in order to obtain the operation status of the image forming apparatus and the usage history of the toner (step S11). Then, steps S12 and S13 are executed to determine in which section the total number of printed sheets Cp falls. Here, three divisions based on two criteria Cp1 and Cp2 (however, Cp1 <Cp2),
・ 0 ≦ Cp ≦ Cp1
Cp1 <Cp ≦ Cp2
・ Cp2 <Cp
Is set.
[0052]
When it is determined that the total number of printed sheets Cp falls in the first section (0 ≦ Cp ≦ Cp1) (“NO” in step S12), the offset value Tod is set to a value Tod1 corresponding to the first section. (Step S14). When it is determined that the total number of printed sheets Cp is in the second section (Cp1 <Cp ≦ Cp2) (“NO” in step S13), the offset value Tod is changed to the value Tod2 corresponding to the second section. (Step S15). Further, when it is determined that the total number of printed sheets Cp falls in the third section (Cp2 <Cp) (“YES” in step S13), the offset value Tod is set to the value Tod3 corresponding to the third section. (Step S16). Note that these three types of offset value candidate values Tod1 to Tod3 may be obtained in advance based on experiments or simulations and stored in the memory 127. Further, the relationship between the total number of printed sheets Cp and the offset value Tod may be converted into a function, the function may be stored in the memory 127, and the offset value Tod corresponding to the total number of printed sheets Cp may be obtained from the function.
[0053]
As described above, according to the embodiment, the offset value Tod is appropriately changed and set by associating the temporal change of the property of the toner with the operation state of the apparatus and the usage history of the toner, and thus the property of the toner is changed. , The offset value Tod can be set accordingly. As a result, the toner consumption can be accurately determined.
[0054]
In the above embodiment, the total number of printed sheets Cp is used as a value indicating directly or indirectly the operation status of the apparatus and the usage history of the toner. , The number of rotations of the developing rollers 40K, 40C, 40M, and 40Y of the developing units 4K, 4C, 4M, and 4Y, the number of rotations of the intermediate transfer belt 71 (the count value of the vertical synchronization signal Vsync), and a predetermined unit. And the total amount of toner consumption (that is, the total amount of toner consumption), and the remaining toner amount Tr remaining in the developing devices 4K, 4C, 4M, and 4Y.
[0055]
In the above embodiment, the offset value Tod is changed and set based only on the total number of printed sheets Cp. In addition to this, the offset value Tod is changed and set in combination with the above-described cumulative value or cumulative number of revolutions. Is also good. In short, values such as the total number of printed sheets Cp and the cumulative number of rotations of the photoconductor 2, that is, two or more values among a plurality of values indicating the operation status of the apparatus and the usage history of the toner are appropriately combined, and the offset value Tod is changed based on them. May be set. For example, the cumulative number of rotations of the photoconductor 2 and the cumulative number of rotations of the developing roller can be combined, or the integrated value of the toner consumption and the remaining amount of toner can be combined. By combining a plurality of values in this manner, the offset value Tod that further reflects the operation status of the apparatus and the usage history of the toner can be obtained, and the toner consumption can be obtained with higher accuracy.
[0056]
FIG. 8 is a flowchart showing another embodiment of the image forming apparatus according to the present invention. This embodiment is greatly different from the previous embodiment in that the offset value Tod is changed and set according to the optimum value of the image forming condition when the image forming condition is adjusted. This is basically the same as the previous embodiment. Therefore, this difference will be described in detail below with reference to FIG.
[0057]
The image forming condition adjusting operation is for adjusting the image forming conditions and controlling the image density to the target density at a predetermined timing such as immediately after the power of the apparatus is turned on or when the number of image forming sheets reaches the predetermined number. . In this embodiment, a patch image of a predetermined pattern is formed while changing and setting the developing bias as a density control factor affecting the image density in multiple stages (step S21). Next, at the timing when each patch image transferred onto the intermediate transfer belt 71 is conveyed to a position facing the patch sensor PS, the respective image densities are detected by the patch sensor PS (Step S22), and the image densities are determined. The correlation with the developing bias is determined. Then, based on the correlation thus obtained, a value of the developing bias is calculated so that the image density matches the target density, and the calculated value is set as the optimum value of the developing bias (step S23).
[0058]
When the optimum value of the developing bias is determined in this way, the image forming is executed while setting the developing bias to the optimum value, so that the image can be formed at the target image density. It should be noted that a number of such concentration control techniques have been proposed in the related art, and any known techniques, including these known techniques, can be applied to the present invention. I do.
[0059]
By the way, when the image forming conditions are changed and set by the image forming condition adjusting operation, the fog amount may change. Therefore, in this embodiment, after the optimization of the developing bias is performed, the optimum value of the developing bias is changed. Is set as the offset value Tod (step S24). Here, offset values corresponding to various developing biases may be obtained in advance based on experiments, simulations, and the like, and stored in the memory 127. Further, the relationship between the developing bias and the offset value Tod may be formed into a function, and the function may be stored in the memory 127, and the offset value Tod corresponding to the optimum value of the developing bias may be obtained from the function.
[0060]
As described above, according to this embodiment, the offset value is changed and set to a value corresponding to the image forming condition every time the image forming condition is optimized. Also, the offset value corresponding to the image forming condition is always set, and the toner consumption can be obtained with high accuracy.
[0061]
In this embodiment, a developing bias is used as an image forming condition. However, the application of the present invention is not limited to this. For example, the image forming condition such as a charging bias and an exposure energy is optimized. The present invention can be applied to an image forming apparatus. In particular, the fog amount is greatly influenced by the difference between the surface potential of the photosensitive member 2 charged by the charging unit 3 and the developing bias, that is, the so-called reverse contrast potential. It is most preferable to apply the present invention to a device for developing, a device for optimizing a charging bias as an image forming condition, or a device for optimizing both a developing bias and a charging bias as an image forming condition.
[0062]
The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the dot counter 200 is configured as an independent functional block. However, for example, the dot counter may be configured as software executed by a CPU provided in either the main controller 11 or the engine controller 12. The above may be realized.
[0063]
Further, for example, in the above-described embodiment, the toner consumption is calculated every time one image is formed in the normal image forming operation. However, the “predetermined unit” of the present invention is not limited to this. It is not a thing but arbitrary. For example, when there is an image forming request corresponding to a plurality of images, the toner consumption may be obtained after forming all the images or every time a predetermined number of images are formed.
[0064]
Further, for example, in the above-described embodiment, the toner remaining amount is determined to be the toner end when the remaining toner amount Tr becomes smaller than the minimum toner amount Tmin. However, based on the calculated toner consumption amount or the remaining toner amount, Thus, other controls can be performed. For example, the timing at which the above-described image forming condition adjustment operation is performed may be determined based on the remaining amount of toner. That is, the image forming condition adjusting operation may be executed when the remaining amount of toner reaches a predetermined value. Since the toner characteristics in the developing device gradually change, and the image density may fluctuate accordingly, determining the execution timing of the image forming condition adjustment operation based on the remaining amount of the toner depends on the image density. This is effective in achieving stability. Further, for example, the amount of toner removed from the photoconductor 2 by the cleaning blade 51 of the cleaning unit 5 and collected in a waste toner tank (not shown) of the cleaning unit 5 is estimated from the total amount of consumed toner. The empty capacity of the waste toner tank may be estimated based on the value.
[0065]
Further, in the above embodiment, the present invention is applied to the image forming apparatus provided with the intermediate transfer belt 71 as the intermediate transfer medium. However, the image forming apparatus provided with the intermediate transfer drum or the intermediate transfer sheet as the intermediate transfer medium is used. The present invention can also be applied to this. In the above-described embodiment, the image forming apparatus is configured to be able to form a full-color image using four color toners of yellow, cyan, magenta, and black. The present invention is not limited to this, and is arbitrary. For example, the present invention can be applied to an apparatus that forms a monochrome image using only black toner.
[0066]
Further, in the above embodiment, the present invention is applied to a printer that receives image data from outside the apparatus and executes an image forming operation based on an image signal corresponding to the image data. An image signal is created inside the apparatus in response to the pressing of the copy button, and a copier that performs an image forming operation based on the image signal or receives image data given via a communication line to execute the image forming operation. It goes without saying that the present invention is also applicable to a facsimile machine to be executed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus of FIG. 1;
FIG. 3 is a block diagram illustrating a configuration of a dot counter.
FIG. 4 is a diagram for explaining a counting procedure by a dot counter.
FIG. 5 is a flowchart illustrating a toner counting operation when an image forming operation is performed.
FIG. 6 is a diagram illustrating a change in the particle size distribution of the toner.
FIG. 7 is a flowchart showing an offset value change setting operation in one embodiment according to the present invention;
FIG. 8 is a flowchart illustrating another embodiment of the image forming apparatus according to the present invention.
[Explanation of symbols]
2 photoreceptor (image carrier), 4 developing unit (developing unit), 4C, 4K, 4M, 4Y developing unit (developing unit), 7 transfer unit (transfer unit), 12 engine controller (consumption amount) Calculating means, offset value setting means, remaining toner calculating means), 40C, 40K, 40M, 40Y developing roller (toner carrier), 71 intermediate transfer belt (intermediate transfer medium), 124 CPU (consumption calculating means) , Offset value setting means, toner remaining amount calculating means) 127: memory, Cp: total number of printed sheets, Tr: toner remaining amount

Claims (10)

An image forming apparatus that forms a toner image in a predetermined unit and calculates a toner consumption amount consumed when the toner image is formed,
A consumption amount calculation for obtaining a toner consumption amount by adding, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image to the total amount of the image forming toner constituting the toner image. Means,
An image forming apparatus comprising: an offset value setting unit configured to change and set the offset value according to an operation state of the apparatus. An image forming apparatus that forms a toner image in a predetermined unit and calculates a toner consumption amount consumed when the toner image is formed,
A consumption amount calculation for obtaining a toner consumption amount by adding, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image to the total amount of the image forming toner constituting the toner image. Means,
An image forming apparatus comprising: an offset value setting unit configured to change and set the offset value according to a toner use history. The image forming apparatus according to claim 1, wherein the offset value setting unit changes and sets the offset value according to a cumulative value of the number of printed sheets. An image carrier capable of carrying an electrostatic latent image corresponding to the toner image while rotating, and attaching the toner carried on the rotating toner carrier to the electrostatic latent image on the image carrier. The image forming apparatus according to claim 1, further comprising a developing unit configured to visualize the electrostatic latent image to form the toner image.
The image forming apparatus, wherein the offset value setting means changes and sets the offset value according to a cumulative rotation speed of at least one of the image carrier and the toner carrier. An image carrier capable of carrying an electrostatic latent image corresponding to the toner image; and forming a toner image by visualizing the electrostatic latent image by attaching toner to the electrostatic latent image on the image carrier. 3. The image forming apparatus according to claim 1, further comprising: a developing unit; and a transfer unit configured to transfer the transferred toner image onto a recording medium after transferring the toner image onto a rotating intermediate transfer medium. 4.
The image forming apparatus, wherein the offset value setting means changes and sets the offset value according to the cumulative number of rotations of the intermediate transfer medium. The image forming apparatus further includes a developing unit that stores toner, and a toner remaining amount calculating unit that determines a remaining amount of toner remaining in the developing device based on an integrated value obtained by integrating the toner consumption amount obtained in the predetermined unit. Item 3. The image forming apparatus according to Item 1 or 2,
The image forming apparatus, wherein the offset value setting means changes and sets the offset value according to at least one of the integrated value and the remaining amount of toner. An image forming apparatus that forms a toner image in a predetermined unit and calculates a toner consumption amount consumed when the toner image is formed,
A consumption amount calculation for obtaining a toner consumption amount by adding, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image to the total amount of the image forming toner constituting the toner image. Means,
An image forming apparatus comprising: an offset value setting unit configured to change and set the offset value according to image forming conditions for forming the toner image. A method of calculating a toner consumption amount for obtaining a toner consumption amount consumed when forming a toner image in an image forming apparatus that forms a toner image in a predetermined unit,
Obtaining a total amount of toner constituting the toner constituting the toner image;
A step of obtaining, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image;
Obtaining a toner consumption amount by adding the total amount and the offset value;
Changing the offset value in accordance with the operation state of the image forming apparatus. A method of calculating a toner consumption amount for obtaining a toner consumption amount consumed when forming a toner image in an image forming apparatus that forms a toner image in a predetermined unit,
Obtaining a total amount of toner constituting the toner constituting the toner image;
A step of obtaining, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image;
Obtaining a toner consumption amount by adding the total amount and the offset value;
Changing and setting the offset value in accordance with the toner usage history. A method of calculating a toner consumption amount for obtaining a toner consumption amount consumed when forming a toner image in an image forming apparatus that forms a toner image in a predetermined unit,
Obtaining a total amount of toner constituting the toner constituting the toner image;
A step of obtaining, as an offset value, a toner amount consumed separately from the image forming toner when forming the toner image;
Obtaining a toner consumption amount by adding the total amount and the offset value;
Changing and setting the offset value in accordance with image forming conditions for forming the toner image.

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