Patent Grant
8891983
The present invention relates to an image forming apparatus equipped with a container in which the developer remaining on the image bearing member of the apparatus is recovered.
There have been known image forming apparatuses having: a transferring device which transfers a toner image (developer image) formed on the photosensitive drum (image bearing member) of the apparatus, onto a sheet of recording medium such as paper; and a cleaning device which removes the toner remaining on the peripheral surface of the photosensitive drum after the transfer of the toner image. Generally speaking, a developing device has: a toner container (developer container) for storing toner (developer); and a development sleeve (developer bearing member) which supplies the peripheral surface of the photosensitive drum with the toner in the toner container. A cleaning device has: a cleaning blade which is placed in contact with the peripheral surface of the photosensitive drum to scrape away the toner remaining on the peripheral surface of the photosensitive drum; and a container into which the toner (which hereafter may be referred to waste toner) removed (scraped away) by the cleaning blade is recovered. If waste toner is generated by an amount greater than the capacity of the waste toner collection container, it sometimes occurs that the waste toner spills from the waste toner collection container. If the waste toner spills from the waste toner collection container, it is possible that the image forming apparatus will output unsatisfactory images, the flaws of which are attributable to the waste toner having spilled from the waste toner recover container. Thus, Japanese Laid-open Patent Application 2003-316224 discloses an image forming apparatus which calculates the amount of the waste toner it generates, based on the amount of its toner consumption, and its transfer efficiency. This apparatus calculates the amount by which waste toner is generated, and as it determines when the container would have been filled up with the waste toner, it warns a user that the container will be about to be full, preventing thereby the waste toner from spilling from the waste toner container. In the above-mentioned patent document (which hereafter may be referred to as first patent document), the amount of toner consumption means the amount by which toner transfers onto the area (which hereafter may be referred to as exposed area) of the peripheral surface of the photosensitive drum, from the toner container. The transfer efficiency means the ratio with which the toner supplied to the image formation area of the photosensitive drum is transferred onto a sheet of paper or the like. That is, according to the first patent document, it is possible to obtain the amount of transfer residual toner on the photosensitive drum, that is, the amount of the toner remaining on the peripheral surface of the photosensitive drum after the toner image transfer, by calculating the difference between the amount of toner consumption, that is, the amount by which the toner is supplied to the image formation area of the photosensitive drum, and the amount by which toner is transferred from the image formation area of the photosensitive drum onto a sheet of paper or the like. Thus, it is possible to calculate the amount by which the waste toner is recovered into the waste toner collection container.
However, the waste toner, which is to be recovered into the waste toner collection container, is not the transfer residual toner alone. It includes the toner which transfers onto the peripheral surface of the photosensitive drum, but does not contribute to image formation, that is, the toner which is consumed during an image forming operation, but remains adhered to the areas of the peripheral surface of the photosensitive drum, which correspond to the blank portions of the image to be formed (which hereafter may be referred to as unexposed portions). Hereafter, the toner that adheres to the unexposed portions of the peripheral surface of a photosensitive member will be referred to as “stray toner”. The first patent document 1 does not take the stray toner into consideration. In a case where an image which is low in print ratio is outputted, the exposed portion of the image formation area of the photosensitive drum becomes greater in size than the unexposed portion of the image formation area, and therefore, the amount of the stray toner, that is, the toner that adheres to the unexposed portion is substantial. That is, the amount of the stray toner is unignorable when calculating the amount of the waste toner. In other words, if the amount of waste toner is calculated simply calculating the amount of the transfer residual toner, that is, without taking the amount of the stray toner into consideration, the calculated (estimated) amount by which the waste toner is recovered into the waste toner collection container is substantially different from the actual amount, making it impossible to accurately determine whether or not the waste toner collection container has been filled up with the waste toner.
Thus, the primary object of the present invention is to provide an image forming apparatus which is capable of taking into consideration the developer having adhered to the unexposed portion of the image formation area of its image bearing member, and therefore, is capable of accurately calculating the amount by which the developer is removed by its cleaning member and accumulated in its waste toner collection container.
According to an aspect of the present invention, there is provided an image forming apparatus comprising an image bearing member; an exposure device for forming an electrostatic latent image on said image bearing member by exposure to light; a developing device including a developer container for containing a developer, and a developer carrying member for forming a developed image on said image bearing member by visualizing the electrostatic latent image by supplying the developer contained in said developer container to said image bearing member; a transferring device for transferring the developed image onto a recording material an intermediary transfer member; a cleaning device including a cleaning member for removing the developer remaining on said image bearing member after transfer of the developed image, a collection container for collecting the developer removed by said cleaning member; a measuring device for measuring an amount of the developer in said developer container; first calculating means for calculating an amount of the developer supplied from said developer container to said image bearing member; second calculating means for calculating an amount of the developer transferred onto the recording material or the intermediary transfer member; and a controller for outputting an information signal relating to a developer amount accumulated in said collection container on the basis of an amount of the developer calculated by said first calculating means and an amount of the developer calculated by said second calculating means, wherein said first calculating means calculates an amount of the developer supplied to said image bearing member from an inside of said developer container, on the basis of an amount of the developer measured by said measuring device after an image forming operation, and an amount of the developer initially contained in said developer container, and said controller outputs the information signal relating to the developer amount accumulated in said collection container on the basis of the amount of the developer calculated by said first calculating means and the amount of the developer calculated by said second calculating means.
According to the present invention, it is possible to accurately calculate the amount of the developer having been removed by the cleaning member of an image forming apparatus and having accumulated in the waste toner collection container of the image forming apparatus.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.
Parts (a) and (b) of
First, referring to
The image forming apparatus in the first embodiment has: a photosensitive drum 1 as an image bearing member; a charging device 2; an exposing device 3, a developing device 4; a transferring device 5; a cleaning device 6; and a fixing device 7. The photosensitive drum 1 rotates in the direction indicated by an arrow mark E in
Next, the image forming operation of the image forming apparatus in the first embodiment is briefly described. First, the charge device 2 uniformly charges the peripheral surface of the photosensitive drum 1 to a preset potential level. Then, the exposing device 3 forms an electrostatic latent image on the uniformly charged peripheral surface of the photosensitive drum 1 (image bearing member), by projecting a beam of laser light upon the peripheral surface of the photosensitive drum 1. Meanwhile the toner in the toner container 44 is conveyed onto the development sleeve 41 by the stirring/conveying member 43, forming thereby a layer of toner on the peripheral surface of the development sleeve 41. Then, as the development sleeve 41 rotates, the toner layer is frictionally charged between the peripheral surface of the development sleeve 41 and development blade 42. The image forming apparatus in this embodiment is designed so that the toner is to move onto the positively charged surface, in the development and transfer processes. Thus, the toner is negatively charged. The development sleeve 41 bearing the toner develops the electrostatic latent image onto a visible image by supplying the peripheral surface of the photosensitive drum 1 with the toner on its peripheral surface. Then, the transferring device 5 transfers the visible image, that is, the image formed of the toner (developer), onto a sheet of recording medium such as paper, or an intermediary transfer belt as an intermediary transferring member. In a case where the design of the image forming apparatus is such that the toner image is to be transferred onto the intermediary transferring member, the toner image is transferred onto a sheet of recording medium such as paper, from the intermediary transferring member. After the transfer of the toner image onto the sheet of recording medium, the toner image is subjected to heat and pressure by the fixing device 7, whereby the toner is fixed to the sheet of recording medium. After the transfer of the toner image onto the sheet of recording medium or intermediary transferring member, a certain amount of toner remains on the peripheral surface of the photosensitive drum 1. The toner remaining on the peripheral surface of the photosensitive is a combination of the “transfer residual toner” and “stray toner”. The combination is removed by the cleaning blade 61, and is recovered as waste toner into the collection container. The “transfer residual toner” means such toner that transfers from the toner container 44 onto the area (which will be referred to as “exposed area”) of the photosensitive drum 1, across which an electrostatic latent image is formed, but, failed to be transferred onto a sheet of paper or the like after the toner image formation, therefore remaining on the exposed area of the peripheral surface of the photosensitive drum 1. The “stray toner” means such toner that transferred from the toner container 44 onto the area (which hereafter will be referred to as “unexposed area”) of the image formation area of the peripheral surface of the photosensitive drum 1, other than the exposed area, and adhered to the unexposed area. The stray toner is generated because when toner is frictionally charged while the toner layer of the development sleeve 41 is regulated in thickness by the development blade 42, a certain amount of toner is charged to the opposite polarity from the normal polarity. Since the stray toner is opposite in polarity from the normally charged toner, it does not transfer onto a sheet of paper or the like. Therefore, it remains on the photosensitive drum 1 after the image transfer onto the sheet or paper or the like.
Next, the general concept of how the amount of the waste toner is calculated by the image forming apparatus in this embodiment is described. Here, the waste toner amount is the amount of the toner (developer) removed from the peripheral surface of the photosensitive drum 1 by the cleaning blade 61 and recovered into the collection container 62. That is, in the first embodiment, the waste toner amount is the sum of the transfer residual toner amount and stray toner amount. The transfer residual toner amount is the amount of the toner which was not transferred onto a sheet of paper or the like after the toner image formation on the photosensitive drum 1, and is remaining on the exposed area of the image formation area of the photosensitive drum 1 after the toner image transfer. The stray toner amount is the amount of the toner which transferred onto the unexposed area of the image formation area of the photosensitive drum 1 from the toner container 44, and adhered thereto. Hereafter, the amount by which the toner transferred onto the photosensitive drum 1 from the toner container 44 will be referred to as toner consumption amount. The amount by which the toner transferred onto the exposed area of the photosensitive drum 1 from the toner container 44 will be referred to as the development toner amount. Thus, the toner consumption amount can be expressed as the sum of the development toner amount and stray toner amount. Further, the amount by which the development toner is transferred from the exposed area of the photosensitive drum 1 onto a sheet of paper or the like to form an image on the sheet of paper or the like, will be referred to as the image formation toner amount, and the amount of the toner which failed to be transferred onto a sheet of paper or the like after the toner image formation on the photosensitive drum 1, and is remaining on the exposed area of the photosensitive drum 1 after the toner image transfer, will be referred to as the transfer residual toner amount. Thus, the waste toner amount can be obtained by calculating the difference between the toner consumption amount and image formation toner amount. The image forming apparatus in the first embodiment has a first calculating means that calculates the toner consumption amount, and a second calculating means that calculates the image formation toner amount. Further, the image forming apparatus has a computing means that obtains the waste toner amount based on the toner amount calculated by the first calculating means, and the toner amount calculated by the second calculating means. In this embodiment, the roles of the first and second calculating means, and computing means, are played by the CPU 9 of the image forming apparatus.
In order to calculate the toner consumption amount, the amount of the toner in the toner container 44 (which hereafter will be referred to as residual toner amount) has to be obtained. In this embodiment, the image forming apparatus is equipped with a device for measuring the amount of the toner in the toner container 44. More concretely, the device is made up of an electrode 45, which is in the form of an antenna, and a detection circuit 82. Next, referring to
Next, referring to
Next, the method for adjusting image forming apparatus in this embodiment in the halftone density is described. As the image forming apparatus in this embodiment is requested by a user to output images, the density data i for each picture element can be obtained from the image data by the image processing section of the image forming apparatus. Then, the control section 9 of the image forming apparatus creates an exposure pattern which reflects the density data i, and controls the exposing device 3 during an image forming operation. However, even if the exposure pattern remains the same, the halftone density of the image formed on recording medium is affected by various factors, for example, the nonuniformity in the sensitivity of the photosensitive drum 1, thickness of the dielectric layer of the photosensitive drum 1, etc., and also, the changes in chargeability and fluidity of the toner, which are attributable to the phenomenon that the external toner additive is buried into toner particles, and/or becomes separated from toner particles. Therefore, the image forming apparatus in this embodiment is adjusted in halftone density with preset interval, in order to keep the apparatus stable in halftone density.
The method for adjusting the image forming apparatus in this embodiment in halftone density is as follows: During an image forming operation, multiple test images which are different in exposure pattern are formed on multiple sheets of recording medium, one for one, for every preset number of prints. Then, the test images are measured in density with the use of a density measuring device 8 made up of a light emitting element, a light sensing element, and a detection circuit. The density measuring device projects a beam of light upon the test image with the use of its light emitting element, and catches the light reflected by the test image, with the use of its light sensing element. Then, it converts the amount of electric charge generated by the light sensing element, into voltage by its detection circuit, and outputs the voltage to the computing means. The computing means converts the value of the voltage from the detection circuit, into density, with reference to a conversion table prepared in advance. Since the amount of electric charge generated by the light sensing element is proportional to the density of the test image, it is possible to obtain the correlation between the exposure pattern and the test image. That is, by forming the test image on recording medium through the processes of exposure, development, and transfer, and detecting density of the test image (toner image) with the use of the light sensing element, it is possible to obtain the relationship among the transfer efficiency X(i), development efficiency Y(i), exposure area ratio Z(i), relative to the density data i. Here, the exposure area ratio Z(i) means the ratio of the area of a given picture element, which needs to be exposed to form an image according to the density data i, relative to the entire area of the picture element. The development efficiency Y(i) means the amount by which the toner is supplied to the exposed area to form an image according to the density data i. The transfer efficiency X(i) is the ratio with which the toner on the photosensitive drum 1 is transferred onto a sheet of paper or the like when the density data is i.
In this embodiment, the test images are formed with the tone set at nine different levels in terms of exposure area ratio. The image outputted with the exposure area ration set to Z(i) is measured in density, to obtain the product X(i)×Y(i) of the transfer efficiency and development efficiency, which is stored in the first storing means of the memory m of the process cartridge B. During an image forming operation, the exposure area ratio Z(i), with which the peripheral surface of the photosensitive drum 1 is to be exposed is calculated with reference to the X(i)×Y(i) in the first storing means, and the exposing device 3 is controlled based on the thus obtained exposure area ratio Z(i).
Next, referring to
The development toner amount is the sum of the products of the development efficiency Y(i) and exposure area ratio Z(i). Therefore, it can be expressed as Σ{Y(i)×Z(i)} (Step S2).
The stray toner amount is the difference between the development toner amount Σ{Y(i)×Z(i)} and toner consumption amount ΔT. Therefore, it can be expressed as ΔT−Σ{Y(i)×Z(i)} (Step S3).
The image formation toner amount is the product of the development toner amount Σ{Y(i)×Z(i)} and transfer efficiency X(i). Therefore, it can be expressed as Σ{Y(i)×Z(i)}×Z(i) (Step S4).
The transfer residual toner amount is the difference between the development toner amount Σ{Y(i)×Z(i)} and image formation toner amount Σ{Y(i)×Z(i)}×Z(i). Therefore, it can be expressed as Σ[Y(i)×Z(i)×{1−X(i)}] (Step S5).
Next, the specific method used by the image forming apparatus in this embodiment for calculating the waste toner amount is described. When the density data is i, the waste toner amount is the sum of the stray toner amount ΔT−Σ{Y(i)×Z(i)} and transfer residual toner amount Σ[Y(i)×Z(i)×{1−X(i)}]. Therefore, it can be expressed as ΔT−Σ{X(i)×Y(i)×Z(i)} (Step S6). That is, the waste toner amount can be obtained by calculating the difference between the toner consumption amount ΔT and image formation toner amount Σ{X(i)×Y(i)×Z(i)}.
Further, the image formation toner amount Σ{X(i)×Y(i)×Z(i)} is calculated using the product X(i)×Y(i) of the transfer efficiency and development efficiency, and the exposure area ratio Z(i), which are stored in the memory m for every image forming operation, and is added to the value of the image formation toner amount in the memory m so that the cumulative image formation toner amount is stored in the memory m. In the first embodiment, the toner consumption amount ΔT detected with the use of the aforementioned antennas 45 is compared with the cumulative image formation toner amount in the memory m, in order to obtain the waste toner amount. If the toner consumption amount ΔT is the same as the cumulative image formation toner amount Δt, it means that the entirety of the toner consumed from within the toner container 44 was used for image formation. If the toner consumption amount ΔT is greater than the cumulative image formation toner amount Δt, it means that the amount by which the toner was consumed from within the toner container 44 is greater than the cumulative image formation toner amount, that is, the total amount of the toner used for image formation and moved out of the image forming apparatus, and therefore, there is waste toner in the collection container 62. As described above, by calculating the difference between the toner consumption amount ΔT and cumulative image formation toner amount Δt, it is possible to obtain the amount of the waste toner recovered into the collection container 62.
Next, referring to
Next, referring to
As described above, the waste toner amount calculated by the image forming apparatus in the first embodiment is the sum of the transfer residual toner and stray toner amount. Therefore, the apparatus can accurately predict when the waste toner container 62 will be filled up with the waste toner. Therefore, a user is reliably warned that the waste toner container 62 of the image forming apparatus is about to be filled with the waste toner. Therefore, the image forming apparatus can be prevented from outputting unsatisfactory images, the flaws of which are attributable to the spilling of the waste toner from the waste toner collection container of the apparatus.
Next, referring to
Referring to
Next, the method used by the image forming apparatus in the second embodiment to predict when the waste toner collection container 62 will be filled up with the waste toner is described. As the low-toner condition is detected by the above described toner amount detecting device which uses a beam of light to detect the presence of toner, the CPU 9 reads the cumulative amount ΔT of the image formation toner in the memory m of the process cartridge B. The toner consumption amount ΔS, which is the difference between the initial toner amount T0 stored in advance in the memory m of the process cartridge B, and the toner amount Tn which is the amount of toner in the toner container 44 in the low-toner condition. Thus, the waste toner amount in the low-toner condition can be calculated by subtracting the cumulative image formation toner amount Δs from the toner consumption amount ΔS. Further, the CPU 9 reads the cumulative number of the prints outputted before the low-toner condition occurred, from the second storing means of the memory m, and calculates the amount by which the waste toner is accumulated in the collection container 62 per print (which hereafter will be referred to as “waste toner accumulation speed”), based on the waste toner amount and cumulative number of the print. Then, it estimates the amount by which the waste toner can be continuously recovered into the collection container 62, based on the preset waste toner capacity of the collection container 62 and the calculated waste toner amount. Then, it predicts how many prints can be outputted before the collection container 62 is filled up with the waste toner, by dividing the estimated amount by which the waste toner is recoverable into the collection container 62 before the container 62 is filled up with the waste toner, with the waste toner accumulation speed. Then, it informs a use how many prints can be outputted before the collection container 62 is filled up with the waste toner.
Table 1 shows the waste toner amount in the collection container 62 of the image forming apparatus, the waste toner capacity of which is 5 g, right after the occurrence of the low-toner condition, and the estimated number by which prints can be outputted by the image forming apparatus before the collection container 62 will be filled up with the waste toner. In the experiment carried out to create Table 1, in order to change the waste toner amount, the development bias was intentionally set to increase the stray toner amount, instead of using the normal development bias. Referring to Table 1, if the amount of the waste toner in the collection container 62 is 3 g in the low-toner condition, a space large enough for 2 g of waste toner remains in the collection container 62. Therefore, it can be predicted that 6,000 prints will have been outputted before the collection container 62 runs out of the space for the waste toner, assuming that the speed with which the waste toner is accumulated in the collection container 62 after the occurrence of the low-toner condition remains the same as that before the occurrence of the low-toner condition. Therefore, the CPU 9 informs a user that 2,000 more prints can be outputted before the collection container 62 is filled up with the waste toner. In comparison, if the amount of the waste toner in the collection container 62 is 5 g in the low-toner condition, it is highly possible that the image forming apparatus will output unsatisfactory images, the flaws of which are attributable to the overfilling of the collection container 62 with the waste toner. Therefore, a user is prompted to replace the process cartridge B. Incidentally, in the second embodiment, when the collection container 62 will be filled up with the waste toner is predicted by storing the cumulative number by which prints were outputted, and calculating the waste toner accumulation speed from the cumulative print count. However, when the collection container 62 will be filled up with the waste toner can be predicted with the use of a parameter other than the cumulative print count. For example, it can be predicted with the use of cumulative length of the rotation of the photosensitive drum 1 or development sleeve 41, which indicates the history of the usage of the process cartridge B.
As described above, the image forming apparatus in the second embodiment can calculates the waste toner amount which is the sum of the transfer residual toner and stray toner amount. Therefore, it can accurately predict when its collection container will be filled up with the waste toner. Although it cannot continuously detect the residual toner amount in its toner container, and therefore, cannot continuously detect the waste toner amount, it can predict when its waste toner collection container will be filled up with the waste toner. Thus, it can issue a warning that the collection container is about to be filled up with the waste toner, and therefore, can be prevented from outputting unsatisfactory images, the flaws of which are attributable to the overflowing of the waste toner from the collection container.
Incidentally, reducing the collection container 62 in waste toner capacity reduces the length of time it takes for the container 62 to be filled up with the waste toner, and therefore, requires that when the container 62 will be filled up with the waste toner has to be more accurately predicted. That is, the second embodiment of the present invention is more effective when it is applied to a smaller collection container (62) than when it is applied to a larger collection container (62).
(Miscellanies)
In the case of the image forming apparatus in this embodiment, the CPU 9 issues the above described warning on the display of the image forming apparatus, in response to the detection signals. However, this embodiment is not intended to limit the present invention in terms of how and where the warning is issued. For example, the warning may be displayed on a terminal which is in connection to the image forming apparatus through a network, and/or the on-going image forming operation may be stopped, in response to the detection signals.
While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.
This application claims priority from Japanese Patent Applications Nos. 175785/2011 and 133148/2012 filed Aug. 11, 2011 and Jun. 12, 2012, respectively, which are hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 7689156 | Shishikura | Mar 2010 | B2 |
| 20090010659 | Watanabe | Jan 2009 | A1 |
| 20110026948 | Nagasu et al. | Feb 2011 | A1 |
| Number | Date | Country |
|---|---|---|
| 63-247783 | Oct 1988 | JP |
| 2003-316224 | Nov 2003 | JP |
| Entry |
|---|
| Machine translation of JP 2003-316224 dated Jan. 6, 2014. |
| Number | Date | Country | |
|---|---|---|---|
| 20130039671 A1 | Feb 2013 | US |
