JP2016151677A - Image forming apparatus - Google Patents

Abstract

Cost reduction and size reduction can be achieved, and execution of forced toner consumption can be controlled. An image carrier, an electrostatic forming unit, a developing unit, a toner consumption calculating unit for calculating a toner consumption amount consumed from the developing unit based on an image area ratio, and a toner consumption calculating unit. Toner supply means 519 for supplying toner in an amount corresponding to the toner consumption calculated by the above, and forced toner consumption control for forcibly consuming toner in the developer storage container The printer 600 including the consumption control unit 522 includes a toner amount detection unit such as a toner amount detection sensor 46 that detects the toner amount in the developer container, and the forced toner consumption control unit 522 is detected by the toner amount detection unit. The forced toner consumption control is executed based on the difference between the detected toner amount and the target toner amount in the developer storage container. [Selection] Figure 2

Description

  The present invention relates to an image forming apparatus.

  Conventionally, when an image with a low image area ratio is output continuously, an image that executes a forced toner consumption mode in which toner in a developer storage container of a developing device that has deteriorated due to excessive rubbing or stirring is forcibly consumed Forming devices are known.

  For example, Patent Document 1 discloses image formation for determining whether to execute the forced toner consumption mode based on the result of detecting the density of a reference image by an image density sensor and the image area ratio calculated based on image information. An apparatus is disclosed. In this image forming apparatus, when determining whether to execute the forced toner consumption mode, not only the calculation result of the image area ratio but also the detection result of the image density sensor is considered. As a result, the execution or non-execution of the forced toner consumption mode can be appropriately determined as compared with the case where only the calculation result of the image area ratio is used, and the situation where toner is unnecessarily consumed can be suppressed.

  However, the image forming apparatus disclosed in Patent Document 1 requires the image density detection result by the image density sensor to determine whether to execute or not execute the forced toner consumption mode. For this reason, an image density sensor must be provided, and there is a problem in that the cost and the size are increased.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to an image carrier, electrostatic forming means for forming an electrostatic latent image on the image carrier based on image information, and a developer container. A developing unit that develops an electrostatic latent image formed on the image carrier into a toner image using the toner stored in the toner, and calculates a toner consumption amount consumed from the developing unit based on an image area ratio Toner consumption calculating means, toner supply means for supplying toner in an amount corresponding to the toner consumption calculated by the toner consumption calculating means, and toner in the developer storage container An image forming apparatus comprising forced toner consumption control means for executing forced toner consumption control means for forcibly consuming the toner, and further comprising toner amount detection means for detecting a toner amount in the developer container, wherein the forced toner consumption control is performed. Stage, based on the difference between the target toner amount of the developer accommodating container and detecting the amount of toner the toner amount detecting means detects, is characterized in that to perform the forced toner consumption control.

  According to the present invention, it is possible to obtain a specific effect that the cost and size can be reduced and the execution of forced toner consumption can be controlled.

1 is a schematic configuration diagram of a printer according to an embodiment. Explanatory drawing of the control system of a printer. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a developing device. 6 is a flowchart for explaining an operation for supplying toner into a developer container. 6 is a flowchart for explaining a control operation of execution or non-execution of a forced toner consumption mode in the printer according to the embodiment. 6 is a flowchart for explaining a control operation of execution or non-execution of a forced toner consumption mode in consideration of a photosensitive member driving distance.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described.
FIG. 1 is a schematic configuration diagram of the printer. An outline of a four-color full-color image forming apparatus as a printer will be described. The printer 600 is a tandem type color image forming apparatus in which process cartridges 1Y, 1M, 1C, and 1K as four image forming units are arranged along the traveling direction of the intermediate transfer belt 7 (A direction in FIG. 1). It is. The number of colors is not limited, and process cartridges of five or more colors may be employed. Each color process cartridge 1 charges the surface of a photoconductor as an image carrier with a charging device, forms an electrostatic latent image with an exposure device, and forms a toner image with a developing device as developing means. These devices are each held by a common holding body and integrally attached to and detached from the device main body so that they can be exchanged simultaneously.

  Each color process cartridge 1 can be attached to and detached from the main body of the printer 600 by releasing the stopper. In the following description, the subscripts Y, M, C, and K indicate members for yellow, magenta, cyan, and black, respectively. The mechanism of the process cartridge is almost the same except that the color of the toner used is different.

  The printer 600 includes a printer unit 100, a paper feeding unit 200, and a scanner unit 300 attached on the printer unit 100. In the printer unit 100, four process cartridges 1Y, 1M, 1C, and 1K are stretched along a plurality of stretching rollers along an intermediate transfer belt 7 as an intermediate transfer member that moves in the direction of arrow A in FIG. Has been placed. The printer unit 100 includes an exposure device 6 as an exposure unit, a fixing device 12 as a fixing unit, and the like.

  In the process cartridge 1, a charging device 3, a developing device 4, a photoconductor cleaning device 5, a charge removal device, and the like are disposed around a photoconductor 2 as a latent image carrier. The photosensitive member 2 has a drum shape in which an organic photosensitive layer is formed on the surface of a drum base, and is rotated in the clockwise direction in FIG. 1 by a rotation driving device. The charging device 3 has a roller shape, and a charging bias is applied to generate a discharge between the charging device 3 and the photoconductor 2 while being in contact with or in proximity to the photoconductor 2, whereby the photoconductor 2. To uniformly charge the surface. The charging device 3 has a metal core bar covered with a conductive elastic layer made of a conductive elastic material. Instead of a method of bringing a charging member such as a charging roller into contact with or close to the photosensitive member 2, a non-contact charging method such as corona charging may be adopted.

  The uniformly charged surface of the photoconductor 2 is optically scanned by a laser beam emitted from the exposure device 6 and carries an electrostatic latent image. Below the process cartridge, an exposure device 6 serving as a latent image writing unit is disposed, and image information of an original image optically read by the scanner unit 300 or an image input from an external device such as a personal computer. Based on the information, the photoconductor 2 is optically scanned with laser light emitted from a laser diode as a light source. By this optical scanning, an electrostatic latent image is formed on the photoreceptor 2. Specifically, the potential is attenuated at the portion irradiated with the laser light in the entire area of the uniformly charged surface of the photosensitive member 2. Thereby, an electrostatic latent image is obtained in which the potential of the laser irradiation portion is smaller than the potential of the other portion (background portion).

  The exposure device 6 irradiates the photoconductor 2 through a plurality of optical lenses and mirrors while polarizing the laser light emitted from the light source in the main scanning direction by a polygon mirror rotated by a polygon motor. In addition, you may employ | adopt what performs optical writing by the LED light emitted from several LED of the LED array.

  Subsequently, the electrostatic latent image formed on the surface of the photoreceptor 2 in this manner is visualized by attaching a charged toner by the developing device 4. As will be described later, the developing device 4 includes a developing unit that encloses a developing roll, and a developer transport unit that stirs and transports the developer in the developer storage container. The developer transport section includes a screw member having a rotary shaft member whose both ends in the axial direction are rotatably supported by bearings, and a spiral blade projecting spirally on the peripheral surface thereof. ing. As the screw member rotates, the developer is stirred and conveyed to the developing roller. This printer is provided with a toner replenishing means for replenishing toner to the developer transport section of the developing device. In the developing device 4, toner is supplied to the developer transport unit. The developing roller accommodated in the developing unit faces the screw member and also faces the photoreceptor 2 through an opening provided in the casing.

  The developing roller includes a cylindrical developing sleeve made of a nonmagnetic pipe that is driven to rotate, and a magnet roller fixed inside the developing sleeve so as not to rotate with the sleeve. Then, while the developer supplied from the screw member is carried on the sleeve surface by the magnetic force generated by the magnet roller, the developer is transported to the developing region facing the photoreceptor 2 as the sleeve rotates. A developing bias having the same polarity as the toner and larger than the electrostatic latent image of the photosensitive member 2 and smaller than the uniform charging potential of the photosensitive member 2 is applied to the developing sleeve. As a result, a developing potential for electrostatically moving the toner on the developing sleeve toward the electrostatic latent image acts between the developing sleeve and the electrostatic latent image on the photoreceptor 2. Further, a non-developing potential that moves the toner on the developing sleeve toward the sleeve surface acts between the developing sleeve and the background portion of the photoreceptor 2.

  By the action of the development potential and the non-development potential, the toner on the development sleeve is selectively transferred to the electrostatic latent image on the photoreceptor 2 and the electrostatic latent image is developed into a toner image. In this manner, the toner image is developed on the photosensitive member 2 and then sequentially transferred onto an intermediate transfer belt 7 as an intermediate transfer member. The transfer residual toner remaining on the surface of the photoconductor 2 after the toner image is transferred to the intermediate transfer belt 7 is removed by the photoconductor cleaning device 5, the surface of the photoconductor is cleaned, and then the surface of the photoconductor 2 is neutralized. The surface potential is initialized by a device such as a static elimination lamp. As the photoconductor cleaning device 5, a cleaning blade, a cleaning roller, a cleaning brush, or the like can be used, and these may be used in combination. Further, the cleaning efficiency can be increased by applying a voltage having a polarity opposite to that of the toner to these cleaning members.

  The printer 600 is an intermediate transfer type image forming apparatus that once transfers the toner image formed on the photoreceptor 2 to the intermediate transfer belt 7 and then transfers the toner image from the intermediate transfer belt 7 to a transfer material. As the intermediate transfer member, a belt-shaped member is used, but a drum-shaped member may be used. Above the process cartridges 1Y, 1M, 1C, and 1K, in addition to the intermediate transfer belt 7 as an image carrier, a driving roller, a driven roller, a secondary transfer counter roller 9a, four primary transfer rollers 8, and a secondary transfer A roller 9 and an intermediate transfer belt cleaning device 11 are disposed.

  The intermediate transfer belt 7 is stretched by a driving roller, a secondary transfer counter roller 9a, a driven roller, and four primary transfer rollers 8 disposed inside the loop. Then, the intermediate transfer belt 7 moves endlessly in the direction of the arrow A in FIG. The four primary transfer rollers 8 sandwich an endlessly moving intermediate transfer belt 7 between the photoreceptor 2. As a result, primary transfer nips for Y, C, M, and K where the front surface of the intermediate transfer belt 7 and the photoreceptor 2 abut are formed.

  A primary transfer bias is applied to the primary transfer roller 8 by a transfer bias power source. As a result, a transfer electric field is formed between the Y, C, M, and K toner images on the photoreceptor 2 and the primary transfer roller 8. The primary transfer roller 8 can be separated. When only K (black) is transferred, the process cartridges of colors other than K are separated from the intermediate transfer belt 7. The primary transfer roller 8 is composed of an elastic roller having a metal core and a conductive sponge layer fixed on the surface thereof. A primary transfer bias controlled by a constant voltage or a constant current is applied to such a primary transfer roller 8. Instead of the primary transfer roller 8, a transfer charger, a transfer brush, or the like may be employed.

  In such a configuration, the intermediate transfer belt 7 enters the primary transfer nip for Y toner as the photoconductor 2 rotates in the clockwise direction, and the Y toner image is transferred to the intermediate transfer belt 7 by the action of the transfer electric field and nip pressure. The primary transfer. Thereafter, the intermediate transfer belt 7 sequentially passes through the primary transfer nips for C, M, and K. Then, the C, M, and K toner images on the photoreceptors 2C, 2M, and 2K are sequentially superimposed on the intermediate transfer belt 7 and primarily transferred.

  Next, the toner image on the intermediate transfer belt 7 is transferred from the intermediate transfer belt 7 to the recording material P in the secondary transfer portion. In the secondary transfer portion, a nip is formed by sandwiching the intermediate transfer belt 7 between the secondary transfer counter roller 9 a and the secondary transfer roller 9 disposed inside the loop of the intermediate transfer belt 7. The recording material P enters between the intermediate transfer belt 7 and the secondary transfer roller 9 in this nip. While the secondary transfer roller 9 is grounded, a secondary transfer bias is applied to the secondary transfer counter roller 9a by a secondary transfer bias power source. As a result, a secondary transfer electric field for electrostatically moving negative polarity toner from the secondary transfer counter roller 9a side to the secondary transfer roller 9 side between the secondary transfer roller 9 and the secondary transfer counter roller 9a. Is formed. The secondary transfer bias power source has a DC power source, and a constant voltage or a constant current controlled voltage having the same polarity as the normal charging polarity of the toner is applied.

  In a paper feed cassette 201 disposed below the printer unit 100 and containing a plurality of recording materials P stacked in a bundle, a paper feed roller is placed on the top recording material P of the paper bundle. It is in contact. By rotating the paper feed roller at a predetermined timing, the recording material P is sent out in the direction of arrow S in FIG. Near the end of the paper feed path, a registration roller pair 202 is disposed. The registration roller pair 202 rotates both rollers as soon as the recording material P fed from the paper feed cassette 201 is sandwiched between the rollers. Stop. Then, rotation driving is restarted at a timing at which the sandwiched recording material P can be synchronized with the toner image on the intermediate transfer belt 7 in the secondary transfer nip, and the recording material P is sent out toward the secondary transfer nip. The four color superimposed toner images on the intermediate transfer belt 7 brought into intimate contact with the recording material P at the secondary transfer nip are collectively transferred onto the recording material P by the action of the secondary transfer electric field and the nip pressure, and are full color. It becomes a toner image. The toner image on the recording material P is heated and fixed by the fixing device 12 and discharged outside the apparatus.

  On the other hand, the toner remaining on the surface of the intermediate transfer belt 7 without being transferred to the transfer paper P at the secondary transfer nip is collected by the intermediate transfer belt cleaning device 11. As shown in FIG. 1, a toner bottle 400 (Y, M, C, K) that stores toner of each color is detachably disposed above the intermediate transfer belt 7 with respect to the printer 600. The toner stored in each color toner bottle 400 is supplied to the developing device 4 for each color by the toner replenishing means corresponding to each color.

  The main body control unit 500 controls the operations of the units necessary for the operation control provided in the main body of the printer 600 and the devices included in the respective units. The main body control unit 500 will be described below with reference to FIG.

  FIG. 2 is an explanatory diagram of the control system of the printer 600. As shown in FIG. 2, the main body control unit 500 includes a central processing unit (CPU) 501, a memory including a ROM 502 and a RAM 503, input / output I / O ports 504 and 505, and the like. The I / O port 504 is connected to the operation unit 506. The I / O port 505 includes a sheet position detection unit 507, a temperature / humidity sensor 508, a photosensitive member drive motor 509, a belt drive motor 510, an intermediate transfer contact / separation clutch 511, a primary transfer high-voltage power supply 512, a secondary transfer high-voltage power supply 513, and charging. High-voltage power supply 514, development high-voltage power supply 515, LED array 516, image position detector 517, toner amount detection means 518 in the developing device, toner replenishment means 519, image area ratio calculation means 520, toner consumption amount calculation means 521, forced toner consumption It is connected to the control means 522 and the like.

  In an electrophotographic printer, when an image with a low image area ratio continues, the toner external additive is peeled off or buried or the toner base is pulverized by stirring or friction in the developer container of the developing device. . Due to such deterioration of the developer, the chargeability is remarkably deteriorated, and the toner adheres to the white paper portion and the toner is scattered. Therefore, when printing with a low image area ratio continues, the toner is developed on the photosensitive member at the time of non-image output, and the toner in the developer container is forcibly consumed to suppress toner deterioration (forced toner) Consumption control) is widely used. As a criterion for the forced toner consumption, the degree of toner deterioration is predicted from the method of performing the forced toner consumption and the information of the image density sensor so that the toner consumption rate is constant with respect to the driving distance of the photosensitive member, and the threshold value A control method is used in which forced toner consumption is performed when the value exceeds the threshold.

  However, when the image output with a low image area ratio is continuous, the method in which forced toner consumption is performed so that the toner consumption rate is constant with respect to the photosensitive member driving distance, the operating environment of the image forming apparatus and the Use conditions (for example, when a high image area ratio is output continuously and then a low image area ratio image is output continuously), toner deterioration is suppressed, and toner is forcibly consumed unnecessarily. As a result, there is a problem that the efficiency of the toner is deteriorated. In addition, when an image density sensor is used, the degree of toner deterioration (deteriorated toner amount) can be predicted to some extent accurately from the charged state of toner in the developer container by detecting the density of the reference image. This control method can be used for image forming apparatuses that do not use an image density sensor for cost reduction and downsizing, such as monochrome printers that employ a one-component development method. I can't take it. Therefore, in the image forming apparatus of this embodiment, the forced toner consumption is obtained by estimating the toner deterioration state (deteriorated toner amount) in the developer storage container and acquiring the forced toner consumption amount without using the image density sensor. The consumption amount of toner is forcibly consumed to suppress deterioration in image quality due to toner deterioration. Hereinafter, the image forming apparatus of this embodiment will be described.

FIG. 3 is a schematic cross-sectional view illustrating the configuration of the developing device.
As shown in FIG. 3, the toner supplied into the developing device by the toner replenishing means is conveyed to the vicinity of the supply roller 43 by the stirring screw 41 and the supply screw 42 that extend in the same direction as the rotation axis direction of the photoreceptor 2. . The stirring screw 41 and the supply screw 42 are configured to be rotated by a drive motor. The supply roller 43 is made of sponge rubber having a diameter of 12 [mm] and is in contact with the developing roller 44. The supply roller 43 and the developing roller 44 have rotation shafts parallel to each other in the same direction as the rotation shaft direction of the photosensitive member 2 and are configured to be rotated by a drive motor. The developing roller 44 has a diameter of 16 [mm] and is formed using urethane rubber having a volume resistance of 1.0E + 5 to 1.0E + 7. The toner conveyed to the vicinity of the supply roller 43 by the stirring screw 41 and the supply screw 42 is between the supply roller 43 that rotates in the direction of arrow B in FIG. 3 and the developing roller 44 that rotates in the direction of arrow A in FIG. It is frictionally charged and supplied onto the roller surface of the developing roller 44. Further, the toner that is insufficiently charged is scraped off by the regulating blade 45, thereby forming a charged toner thin layer on the roller surface of the developing roller 44, and developing it by bringing it into contact with the photoreceptor 2.

  Here, the regulation blade 45 is made of SUS having a thickness of 1 [mm] and is pressed against the developing roller 44 with a pressure of 20 [N / m] or more, but can form a thin toner layer. If it is a range, it is not this limitation. In the developing device 4, a voltage is applied to the supply roller 43 so that the voltage difference becomes +250 [V] with respect to the developing roller 44 in order to improve toner supply. Further, a voltage is applied to the regulating blade 45 so that the potential difference with respect to the developing roller 44 is +200 [V].

  As shown in FIG. 3, the toner amount detection sensor 46 as the toner amount detection means includes a light emitting element 46a, a light receiving element 46b, and a prism guide 46c. In the toner amount detection sensor 46, light emitted from the light emitting element 46a is incident on the prism guide 46c, and the incident light passes through the prism guide 46c on the light emitting element 46a side at a plurality of height positions in the developer storage container. Is emitted. For example, when the toner amount in the developer container decreases, the upper surface (draft surface) of the toner in the developer container decreases, so that the light emitted from the prism guide 46c is transmitted through the developer container and the light emitting element 46a. Is incident on the prism guide 46c on the side of the light receiving element 46b disposed to face the prism guide 46c on the side, and the incident light passes through the prism guide 46c and is received by the light receiving element 46b. Conversely, when the amount of toner in the developer container is sufficient, the upper surface of the toner in the developer container rises, and the light emitted from the light emitting element 46a through the prism guide 46c on the light emitting element 46a side is developed. Since it is blocked by the toner in the agent storage container, it cannot pass through the developer storage container and is not received by the light receiving element 46b. Based on this detection principle, it is possible to detect the amount of toner in the developer storage container based on the presence or absence of light reception by the light receiving element 46b at a plurality of height positions.

Next, the operation of supplying toner into the developer storage container of the developing device in the image forming apparatus according to the present embodiment will be described with reference to the operation flow of FIG.
FIG. 4 is a flowchart for explaining the operation of supplying toner into the developer container. In FIG. 4, the image area to be printed is calculated from the dot count value (image information) obtained by counting the number of dots forming the image formed on the photoconductor (steps S101 and S102). The area per pixel is 4.48 × 10 ⁻⁴ [mm ² ]. Next, from the image area calculated from the image area ratio, the amount of toner adhering to the photoconductor, that is, the toner consumption amount is calculated (step S103). The calculation formula is as follows.
[Toner consumption] = [Coefficient α] × [Development potential (development bias value)] × [Image area]
The coefficient α is a value determined by the value of the temperature / humidity sensor, and an appropriate value is set.

  Next, the toner replenishing means according to the ability of the toner replenishing means so as to replenish the developer storage container with a certain amount of toner that is substantially equal to or larger than the calculated toner consumption. Driving time is determined, and the toner replenishing means is driven for the driving time to perform the toner replenishing operation (step S104). The toner amount in the replenished developer storage container is detected by the toner amount detection sensor 46 of FIG. 3 (step S105). When the detected toner amount is equal to or greater than a predetermined value, the toner replenishing operation is terminated (step S106: YES).

  On the other hand, when the amount of toner in the developer storage container detected by the toner detection sensor 46 is smaller than a predetermined value, an additional fixed amount of toner is supplied to the developer storage container by the toner supply means (step S106: NO, step S107). In addition, although the fixed amount of toner to be replenished is 3 [g], it is not necessary to limit to this. Thereafter, when the detected toner amount becomes equal to or greater than the predetermined value, the additional quantitative toner supply is terminated (step S106: YES). Then, the fixed amount of toner replenished until the predetermined value is reached is acquired (step S108). Based on the fixed toner supply amount, a difference between the toner consumption amount calculated from the image information and the toner consumption amount consumed from the developing device can be detected. The acquired quantitative toner replenishment amount and photosensitive member driving distance are stored.

  According to the toner replenishing operation described above, when a constant toner amount approximately equal to or corresponding to the toner consumption amount calculated from the image information is supplied to the developer storage container, for example, the image area ratio The amount of toner in the developer container is in the replenished state because the toner in the developer container before replenishment is consumed almost as much as the toner consumption calculated from the image information. Becomes the target toner amount.

  Conversely, when images with a low image area ratio are continuously output, the amount of toner actually consumed from the developing device decreases, and the amount of toner remaining in the developer storage container increases. Therefore, these toners are likely to deteriorate due to rubbing, stirring, or the like. As a result, even if a constant amount of toner corresponding to the toner consumption calculated from the low image area ratio is replenished in the developer storage container, a large amount of toner is deteriorated in the developer storage container. Become. When such deteriorated toner is used for image output, the charging performance of the toner is remarkably deteriorated. For example, toner adhesion (fogging, background dirt) to the white paper portion or toner scattering occurs, and the actual developing device The amount of toner consumed from the toner tends to increase more than the estimated amount of toner consumed.

  Alternatively, when the amount of toner that does not react to the surface electric field of the photosensitive member increases, the amount of toner that is not transferred from the developing device to the photosensitive member increases, and the density of the toner image on the photosensitive member decreases, and is actually consumed from the developing device. The toner consumption tends to be smaller than the estimated toner consumption. For this reason, a deviation occurs between the toner consumption calculated from the image area ratio and the toner consumption actually consumed from the developing means. Therefore, the deviation between the toner consumption calculated from the image information and the toner consumption actually consumed from the developing device has a certain correlation with the deteriorated toner amount. In the printer of this embodiment, the forced toner consumption control is executed / not executed using this correlation.

Next, execution or non-execution of forced toner consumption mode control in the printer of this embodiment will be described with reference to the operation flow of FIG.
FIG. 5 is a flowchart illustrating a control operation for executing or not executing the forced toner consumption mode in the printer of the present embodiment. In FIG. 5, the toner amount in the developer container is detected by the toner amount detection sensor 46 in FIG. 3 (step S201). The difference between the detected toner amount and the target toner amount is calculated (step S202). As described above, the difference has a certain correlation with the amount of deteriorated toner in the developer container. For this reason, forced toner consumption control is executed based on the difference between the detected toner amount in the developer container and the target toner amount. If the difference exceeds the threshold value, forced toner consumption control is executed (step S203: YES, step S204). On the other hand, if the difference does not exceed the threshold value, forced toner consumption control is not executed (step S203: NO). This makes it possible to execute appropriate forced toner consumption control according to the amount of deteriorated toner in the developer container without using an image density sensor that causes an increase in cost and size. By adjusting the forced toner consumption amount using the deteriorated toner amount calculated from the difference between the original toner amount and the original target toner amount, it is possible to suppress unnecessary toner consumption.

Next, a control operation for executing or not executing the forced toner consumption mode in consideration of the photosensitive member driving distance will be described with reference to the operation flow of FIG.
FIG. 6 is a flowchart illustrating a control operation for executing or not executing the forced toner consumption mode in consideration of the photosensitive member driving distance. The operation illustrated in FIG. 6 is performed every 10 [m] of the photosensitive member driving distance based on the execution / non-execution of the forced toner consumption mode control illustrated in FIG. The driving distance of the photosensitive member is not limited because an appropriate value varies depending on the characteristics of the toner.

In FIG. 6, first, an image area to be printed is calculated from a dot count value (image information) obtained by counting the number of dots forming an image formed on the photoconductor. The area per pixel is 4.48 × 10 ⁻⁴ [mm ² ]. Then, from the calculated image area, an average image area ratio with respect to a constant photosensitive member driving distance (= 10 [m]) is calculated (step S301). Next, when the average image area ratio is larger than a predetermined first threshold value R1 (= 2.0 [%]), it is determined that the toner consumption amount is not so small that the toner is deteriorated, and the forced toner is determined. The consumption mode is not executed (step S302: NO, step S303). The first threshold value R1 is set to 2.0 [%], but this is not limited because an appropriate value varies depending on the characteristics of the toner used.

  In step S302, when the average image area ratio with respect to a certain photosensitive member driving distance is equal to or less than the predetermined first threshold value R1, the photosensitive member driving distance after the previous toner replenishment is calculated (step S302: YES). Step S303). The photosensitive member driving distance may be equal to or greater than the photosensitive member driving distance threshold value L1 (= 500 [m]), and the average image area ratio is smaller than the second threshold value R2 (= 1.0 [%]). When the toner is replenished during the previous forced toner replenishment, it is determined that a lot of toner in the developer storage container has deteriorated, and the forced toner consumption is such that the average image area ratio becomes the second threshold value R2. The amount is calculated (step S304: NO, step S305: YES, step S306). Then, a forced toner consumption mode for forcibly consuming the calculated forced toner consumption amount is executed (step S307). The second threshold value R2 is set to 1.0 [%]. However, the value is not limited as long as the value is smaller than the first threshold value R1, and an appropriate value varies depending on the characteristics of the toner to be used.

  In step S305, when the average image area ratio is equal to or greater than the second threshold value R2 (= 1.0 [%]), it is determined that the toner has been frequently replaced even after being replenished during the previous forced toner replenishment. The forced toner consumption mode is not executed (step S305: NO). If the photosensitive member driving distance is less than the photosensitive member driving distance threshold L1 (= 500 [m]) in step S304, it is determined that the new toner replenished by the previous forced toner replenishment has hardly deteriorated, and the average The forced toner consumption is calculated so that the image area ratio becomes the first threshold value R1 (= 2.0 [%]) (step S304: YES, step S308). Then, a forced toner consumption mode for forcibly consuming the calculated forced toner consumption amount is executed (step S307).

  As described above, depending on whether the average image area ratio with respect to the photosensitive member moving distance exceeds the threshold, and further, whether the photosensitive member moving distance from the previous forced toner supply exceeds the threshold, the developer storage container Whether the forced toner consumption mode is executed or not due to a decrease in the toner amount is determined, and the forced toner consumption is calculated. Thereby, unnecessary forced toner consumption can be reduced and wasteful consumption of toner can be suppressed.

  The forced toner consumption mode is executed between the papers when the printing operation is stopped or during continuous printing. Thereafter, all the toner consumed on the photoreceptor is collected by the cleaning blade. The reason why the forced toner consumption mode is executed when the printing operation is lowered is that the user may turn off the power without executing the forced toner consumption mode at the end of the printing operation before the falling time. This is because the forced toner consumption mode (exactly, execution of the consumption execution flow) is surely executed before the printing operation after the fall is started. Of course, it is possible to provide a delay function for turning off the power, and to turn off the power completely after executing the forced toner consumption mode. However, the cost in that case is increased, and it is preferable as a device for cost reduction and miniaturization. Absent.

  The reason why the forced toner consumption mode is executed between papers during continuous printing is that the forced toner consumption mode is not executed during continuous printing and the turnaround time (from the time when a continuous print request is issued until the completion is completed). This is to improve the time). If continuous printing with a large amount of low image area ratio is performed, the time for performing the forced toner consumption mode for obtaining a predetermined average image area ratio becomes long after that. There is a limit (for example, 100 sheets). Of course, this is to give priority to the turnaround time. When the highest priority is to avoid the deterioration of image quality due to toner deterioration, the forced toner consumption mode is in the middle of continuous printing with a large amount of low image area ratio. It is also possible to execute.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
The image carrier using an image carrier such as the photosensitive member 2, electrostatic forming means for forming an electrostatic latent image on the image carrier based on image information, and toner stored in a developer container. A developing unit such as the developing device 4 that develops the electrostatic latent image formed on the body into a toner image; a toner consumption calculating unit 521 that calculates a toner consumption amount consumed from the developing unit based on the image area ratio; , A toner supply unit 519 for supplying toner in an amount corresponding to the toner consumption calculated by the toner consumption calculation unit into the developer storage container, and forced toner consumption for forcibly consuming the toner in the developer storage container An image forming apparatus such as a printer 600 provided with a forced toner consumption control unit 522 that executes control includes a toner amount detection unit such as a toner amount detection sensor 46 that detects the amount of toner in the developer storage container. Over consumption control means, based on a difference between the detection amount of toner the toner amount detecting means detects the target toner amount of the developer accommodating container, perform a forced toner consumption control.
In this aspect, an amount of toner corresponding to the toner consumption calculated based on the image area ratio is supplied into the developer storage container by the toner supply means. Therefore, if the toner consumption calculated based on the image area ratio matches the amount of toner actually consumed from the developer storage container, the toner amount in the developer storage container is maintained at the target toner amount. .
However, when images with a low image area ratio are continuously output and the amount of deteriorated toner in the developer container increases, for example, toner adhesion (fogging, background stains) to the white paper portion or toner scattering occurs. Therefore, the toner consumption amount actually consumed from the developer storage container may be larger than the toner consumption amount calculated from the image area ratio. Alternatively, when the amount of deteriorated toner in the developer storage container increases, for example, the toner charge amount is extremely decreased or reversely charged, so that it becomes difficult for the toner to move to the electrostatic latent image by the developing electric field. The toner consumption actually consumed from the storage container may be smaller than the toner consumption calculated from the image area ratio. In any case, when the amount of deteriorated toner increases, a difference occurs between the toner consumption calculated from the image area ratio and the toner consumption actually consumed from the developing unit. As a result, the toner amount in the developer storage container cannot be maintained at the target toner amount even if the toner replenishing unit replenishes the toner according to the toner consumption calculated based on the image area ratio. Therefore, an increase in the amount of deteriorated toner in the developer container causes a difference between the actual toner amount in the developer container and the target toner amount. That is, the difference between the actual toner amount in the developer container and the target toner amount has a certain correlation with the deteriorated toner amount in the developer container.
Therefore, in this aspect, the toner amount in the developer storage container is detected by the toner amount detecting means, and forced toner consumption control is executed based on the difference between the detected toner amount and the target toner amount. This makes it possible to execute appropriate forced toner consumption control according to the amount of deteriorated toner in the developer container without using an image density sensor that causes an increase in cost and size, which is unnecessary. The situation where toner is consumed can be suppressed.

(Aspect B)
In (Aspect A), the forced toner consumption control means executes forced toner consumption control when the difference is equal to or greater than the threshold value, and does not execute forced toner consumption control when the difference is less than the threshold value. According to this aspect, it is possible to determine the forced toner consumption amount in accordance with the deteriorated toner amount and replenish the actual amount of toner consumption, and thus it is possible to suppress wasteful toner consumption.

(Aspect C)
In (Aspect A) or (Aspect B), the forced toner consumption calculating means for calculating the forced toner consumption based on the difference is provided, and the forced toner calculated by the forced toner consumption calculating means when executing the forced toner consumption control. The consumption amount of toner in the developer container is forcibly consumed. According to this aspect, the forced toner consumption amount that matches the deteriorated toner amount can be calculated and the toner for the actual consumption can be replenished, so that wasteful toner consumption can be suppressed.

(Aspect D)
In (Aspect A), the forced toner consumption control unit executes the forced toner consumption control depending on whether or not the number of times the toner supply unit supplies a constant amount of toner to the developer storage container exceeds a specified number. According to this aspect, the toner amount in the developer storage container can be grasped even if the measurement capability of the toner amount detection sensor as the toner amount detection means is lowered, so that an appropriate amount corresponding to the deteriorated toner amount in the developer storage container can be obtained. Forced toner consumption control can be executed.

(Aspect E)
In (Aspect A) to (Aspect D), the toner consumption amount calculating means calculates the toner consumption amount based on the image area, the temperature / humidity of the use environment, and the development bias value. In this aspect, the toner consumption can be calculated more accurately in consideration of the temperature and humidity of the usage environment. For this reason, the amount of toner in the developer storage container due to the deteriorated toner can be detected more accurately by supplying the toner supply amount of toner based on the toner consumption amount into the developer storage container.

(Aspect F)
In (Aspect A) to (Aspect E), a driving distance calculating unit that calculates a driving distance of the image carrier is provided, and the forced toner consumption control unit is an average image with respect to the driving distance of the image carrier calculated by the driving distance calculator. When the area ratio is less than or equal to the threshold value, forced toner consumption control is executed. In this aspect, unnecessary forced toner consumption can be reduced and wasteful consumption of toner can be suppressed.

(Aspect G)
In (Aspect F), the forced toner consumption control unit performs the forced toner consumption control when the average image area ratio is equal to or less than the threshold value and the number of times of toner supply by the toner supply unit exceeds a specified number. Run. In this aspect, unnecessary forced toner consumption can be reduced and wasteful consumption of toner can be suppressed.

DESCRIPTION OF SYMBOLS 1 Process cartridge 2 Photoconductor 3 Charging device 4 Developing device 5 Photoconductor cleaning device 6 Exposure device 7 Intermediate transfer belt 8 Primary transfer roller 9 Secondary transfer roller 9a Secondary transfer counter roller 11 Intermediate transfer belt cleaning device 12 Fixing device 41 Stirring Screw 42 Supply screw 43 Supply roller 44 Developing roller 45 Regulating blade 46 Toner amount detection sensor 46a Light emitting element 46b Light receiving element 46c Prism guide 46
DESCRIPTION OF SYMBOLS 100 Printer part 200 Paper feed part 201 Paper feed cassette 202 Registration roller pair 300 Scanner part 400 Toner bottle 500 Main body control part 501 CPU
502 ROM
503 RAM
504 I / O port 505 I / O port 506 Operation unit 507 Paper position detection means 508 Temperature / humidity sensor 509 Photoconductor drive motor 510 Belt drive motor 511 Intermediate transfer contact / separation clutch 512 Primary transfer high voltage power supply 513 Secondary transfer high voltage power supply 514 Charging High-voltage power supply 515 Development high-voltage power supply 516 LED array 517 Image position detector 518 Toner amount detection means 519 Toner supply means 520 Image area ratio calculation means 521 Toner consumption calculation means 522 Forced toner consumption control means 600 Printer

Japanese Patent No. 4920908

Claims (7)

Formed on the image carrier using an image carrier, electrostatic forming means for forming an electrostatic latent image on the image carrier based on image information, and toner stored in a developer container Calculated by the developing means for developing the electrostatic latent image into a toner image, the toner consumption calculating means for calculating the toner consumption consumed from the developing means based on the image area ratio, and the toner consumption calculating means Toner replenishing means for replenishing the developer storage container with an amount of toner corresponding to the amount of toner consumed, and forced toner consumption for executing forced toner consumption control for forcibly consuming the toner in the developer storage container And an image forming apparatus including a control unit.
A toner amount detecting means for detecting a toner amount in the developer container;
The forced toner consumption control means executes the forced toner consumption control based on a difference between a detected toner amount detected by the toner amount detection means and a target toner amount in the developer storage container. Image forming apparatus. The image forming apparatus according to claim 1.
The forced toner consumption control means executes the forced toner consumption control when the difference is greater than or equal to a threshold value, and does not execute the forced toner consumption control when the difference is less than the threshold value. Image forming apparatus. The image forming apparatus according to claim 1, wherein
Comprising a forced toner consumption calculating means for calculating a forced toner consumption based on the difference, and storing the developer of the forced toner consumption calculated by the forced toner consumption calculating means when executing the forced toner consumption control. An image forming apparatus for forcibly consuming toner in a container. The image forming apparatus according to claim 1.
The forced toner consumption control means executes the forced toner consumption control depending on whether or not the number of times that a constant amount of toner is supplied to the developer storage container by the toner supply means exceeds a specified number. Image forming apparatus. The image forming apparatus according to claim 1, wherein:
The image forming apparatus according to claim 1, wherein the toner consumption calculating unit calculates the toner consumption based on an image area, temperature and humidity of a use environment, and a developing bias value. The image forming apparatus according to any one of claims 1 to 5,
A driving distance calculating means for calculating a driving distance of the image carrier;
The forced toner consumption control means executes the forced toner consumption control when an average image area ratio with respect to the drive distance of the image carrier calculated by the drive distance calculation means is equal to or less than a threshold value. apparatus. The image forming apparatus according to claim 6.
The forced toner consumption control means executes the forced toner consumption control when the average image area ratio is equal to or less than a threshold value and the number of times of toner replenishment by the toner replenishment means exceeds a predetermined number. An image forming apparatus.

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