JP5312524B2 - Image forming apparatus - Google Patents

Description

  The present invention is generally mounted on an image forming apparatus using an electrophotographic system, and a cartridge that can be mounted on the main body of the image forming apparatus, that is, a process cartridge, a developing device formed into a cartridge, an image forming system, and a cartridge. The present invention relates to a storage medium.

  Here, examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.), an electrophotographic facsimile apparatus, and the like.

  The cartridge that can be attached to and detached from the main body of the electrophotographic image forming apparatus includes an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, a developing unit that supplies a developer to the electrophotographic photosensitive member, and a cleaning device for the electrophotographic photosensitive member. The cleaning means having at least one of the cleaning means. In particular, the process cartridge is a cartridge in which at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrally formed, and the cartridge can be attached to and detached from the electrophotographic image forming apparatus main body. In other words, it means that at least the developing means and the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge is detachable from the main body of the electrophotographic image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. The process cartridge method is adopted. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in electrophotographic image forming apparatuses.

  Furthermore, a method of mounting a memory as a storage means on a process cartridge (hereinafter simply referred to as “cartridge”) and storing information relating to the cartridge in the memory is also disclosed. For example, Japanese Patent Application Laid-Open No. 2004-228561 proposes that cartridge manufacturing lots and types, types of developer (toner), and the like are stored in a memory to perform cartridge quality control.

  There has also been proposed a method for stabilizing the image quality regardless of the usage status of the cartridge by using information stored in a memory mounted on the cartridge. For example, in Patent Document 2, the number of prints (copied) accumulated as the amount of cartridge used in the image forming apparatus main body is recorded in a memory as needed, and the process conditions (image forming conditions) are controlled according to the accumulated value of the number of printed sheets. An image forming apparatus is disclosed.

  In addition, in order to achieve stable image quality, various proposals such as those shown in Patent Document 3, Patent Document 4, Patent Document 5, and the like have been made.

  In Patent Document 3, Patent Document 4, and Patent Document 5, the photosensitive drum is switched by switching the charging bias applied to the charging means and the developing bias applied to the developing means in accordance with the reduction in the film thickness of the photosensitive drum due to the use of the cartridge. An image forming apparatus that suppresses a change in image quality due to a change in film thickness is disclosed.

  Further, as a method for obtaining the usage level of the photosensitive drum with higher accuracy, for example, as disclosed in Japanese Patent No. 3285785, in order to charge the photosensitive drum rotation time information and the photosensitive drum in a memory provided in the cartridge. There has also been proposed a method for accumulating and storing charging bias application time information applied to the charging means and calculating the usage amount of the photosensitive drum with high accuracy using the information.

Japanese Patent Laid-Open No. 10-221938 US Pat. No. 5,272,503 JP 08-146777 A JP-A-10-246994 Japanese Patent Laid-Open No. 11-015214

  Recently, with the widespread use of computers, a wide range of users have come to use printers, copiers, fax machines, etc., and manufacturers have been required to make products accordingly.

  Among them, process cartridges, which are consumables such as printers, copiers, and fax machines, have long life cartridges with a large toner capacity for users with large print volumes who use image forming apparatuses in offices. Multiple types of process cartridges with different toner amounts (lifetime) that can be mounted on the same image forming device body, such as cartridges with a small print volume, such as using an image forming device, and a small toner capacity for users who want low prices May provide.

  In cartridges with different toner capacities (lifetime) that can be mounted on the same image forming apparatus main body, the cartridge configuration is set appropriately according to the toner capacity (lifetime). Therefore, not only the toner capacity is different, but also the film thickness of the photosensitive layer of the photosensitive drum is often set differently. In such a case, even if each cartridge is used for the same number of prints and for the same time, the latent image characteristics (charging characteristics) and development characteristics of the photosensitive drum differ with respect to the usage amount of each cartridge. Because of such differences in latent image characteristics and development characteristics, it has been difficult to correct and stabilize image quality in all cartridges having different toner capacities (lifetime) only with the above-described conventional technology.

  For example, in an S cartridge having a short life (small toner capacity) and an L cartridge having a long life (large toner capacity), process control appropriate for the L cartridge (here, setting of process condition switching according to the amount of drum use) Compare the image density when the same operation is performed for the S cartridge regardless of the type of cartridge. As a result, as shown in FIG. 15, a density difference of 0.05 to 0.1 occurs between the S cartridge and the L cartridge at a halftone density of 25%, and the L cartridge and the S cartridge used in the same image forming apparatus. Different image quality results in different image quality.

  In other words, when the same image is printed, a density difference is generated due to different types of cartridges to be used.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide an apparatus capable of forming an image with stable image quality even when a plurality of types of cartridges are used.

There are the following configurations for solving the above-mentioned problems. Select a first cartridge and a second cartridge in which the initial amount of toner stored in the developer storage unit storing toner for forming a toner image on the image carrier is larger than that of the first cartridge A detachable image forming apparatus, wherein the first cartridge or the second cartridge stores identification information for identifying the first cartridge and the second cartridge A control unit that selects an image forming condition from a plurality of settings for setting the image forming condition based on the identification information and information on the usage amount of the cartridge, and the control unit includes: When the amount of cartridge used is the same, the image formation using the first cartridge is performed using the second cartridge, and the image formation is performed using the second cartridge. In addition, it is possible to control to reduce the potential difference between the bright portion potential of the electrostatic latent image formed on the image carrier and the development DC voltage applied to the developing means for developing the electrostatic latent image into a toner image. In addition, when an image is formed using the unused first cartridge, the static image formed on the image carrier is formed more than when an image is formed using the unused second cartridge. An image forming apparatus , wherein a potential difference between a bright portion potential of an electrostatic latent image and a development DC voltage applied to a developing unit that develops the electrostatic latent image into a toner image is reduced .

According to the present invention, even when process cartridges having different initial toner capacities are used in the same image forming apparatus main body based on information stored in storage media provided in a plurality of types of cartridges, the type of each cartridge It is possible to suppress variations in the image due to the difference between the two.

Sectional drawing which shows one Example of the process cartridge concerning this invention Sectional drawing which shows one Example of the image forming apparatus concerning this invention The figure which shows the characteristic of the bright part electric potential with the film thickness difference of the photosensitive layer of the photosensitive drum The figure which shows an example which corrected the bright part electric potential by the film thickness difference of the photosensitive layer Transition of conventional line width with S and L cartridges 1 is a block diagram showing an image forming apparatus and a process cartridge according to the present invention. The block diagram of the memory control concerning this invention. Explanatory drawing when density adjustment is performed with DC voltage. FIG. 6 is a diagram illustrating process setting switching timing according to the first embodiment. 3 is a flowchart showing a process control operation in the first embodiment. The graph which shows the effect of this invention in a halftone density. Transition of line width when Example 1 is performed. Explanatory drawing when changing the concentration center setting with DC voltage FIG. 10 is a diagram illustrating process setting switching timing according to the second embodiment. Transition of halftone density with multiple types of conventional cartridges. FIG. 3 is a diagram illustrating details of storage contents of a memory according to the first embodiment. FIG. 6 is a diagram illustrating details of storage contents of a memory according to the second embodiment.

Hereinafter, an image forming apparatus and a cartridge according to the present invention will be described in more detail with reference to the drawings.

  First, an embodiment of an electrophotographic image forming apparatus to which a cartridge constructed according to the present invention can be attached and detached will be described with reference to FIGS. The image forming apparatus of the present embodiment is a laser beam printer that receives image information from a host computer and outputs an image, and is a consumable item such as a photosensitive drum as an electrophotographic photosensitive member, other process means, and toner as a developer. Is an electrophotographic image forming apparatus that can be attached to and detached from the main body of the electrophotographic image forming apparatus as a process cartridge.

  The process cartridge C in this embodiment includes a photosensitive drum 1, a contact charging roller 2 that is a charging unit for uniformly charging the photosensitive drum 1, and a developing roller 5 (a developing unit that is disposed opposite to the photosensitive drum 1). (Hereinafter referred to as “developing sleeve 5”) and a developing device 4 including a toner container 4 a that is connected to the developing sleeve 5 and stores a toner t, and a toner container 4 a, and is removed from the photoreceptor 1 by the cleaning blade 10 and the cleaning blade 10. The cleaning means 6 including the waste toner container 11 for storing the residual toner is integrally configured.

  The charging roller 2 is formed by forming a conductive elastic body on the surface of the core metal. The charging roller 2 is rotatably held at both ends of the core metal and is pressed against the outer peripheral surface of the photosensitive drum 1 with a predetermined pressing force. Rotate following rotation. The charging roller 2 has a superposed voltage (Vac + Vdc) of an AC component Vac and a DC component Vdc having a peak-to-peak voltage Vpp that is at least twice the charging start voltage from a high voltage power source provided in the image forming apparatus main body via a cored bar. ) Is applied to the charging roller 2, and the outer peripheral surface of the rotationally driven photosensitive drum 1 is uniformly contact-charged by the AC application method.

The developing sleeve 5 is a non-magnetic aluminum sleeve (roller) coated with a resin layer. Although not shown, a four-pole magnet roll is disposed in the developing sleeve 5. The toner t is carried on the developing sleeve, and is regulated to an appropriate coating amount on the developing sleeve 5 by the developer regulating member 7.
As the toner t accommodated in the toner container 4a, a negatively chargeable magnetic one-component toner is used.

  The developing bias applied to the developing sleeve 5 is, for example, a superimposed voltage of a DC voltage and a rectangular wave AC voltage.

  A toner agitating member 8 is provided in the toner container 4a. The toner in the toner container 4a is agitated and loosened, and the toner is sent to the developing region in the vicinity of the developing sleeve 5.

  In the laser beam printer of this embodiment shown in FIG. 2, the cylindrical photosensitive drum 1 that is an image carrier rotates in one direction around its axis. The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2, and then an electrostatic latent image is formed by an exposure device (such as a semiconductor laser or LED as exposure means) 3. The electrostatic latent image formed on the photosensitive drum 1 is visualized as a toner image by supplying the toner t by the developing device 4. A bias supply power source (not shown) is connected to the developing sleeve 5, and an appropriate developing bias is applied between the photosensitive drum 1 and the developing sleeve 5 by superimposing an AC bias on the above-described DC bias.

  On the other hand, the transfer material P, which is a recording medium accommodated in the paper feed cassette 20, is sent one by one to the registration roller 18 by the paper feed roller 21, and synchronized with the image on the photosensitive drum 1 by the registration roller 18. Sent to the transfer section.

  In the transfer portion, the toner image on the photosensitive drum 1 visualized by the toner t is transferred to the transfer material P by the transfer roller 9. The transfer material P is further conveyed to the fixing device 12, and the toner image is fixed by heat or pressure to become a recorded image.

  The toner that is not transferred after transfer but remains on the photosensitive drum 1 is removed by the cleaning blade 10 and stored in the waste toner container 11. Thereafter, the photosensitive drum 1 is charged again by the charging roller 2 and the above-described steps are repeated.

  Next, the memory 22 as a storage means (storage medium) mounted on the process cartridge (hereinafter simply referred to as “cartridge”) C will be described.

  The cartridge C of this embodiment includes a memory 22 provided on the front portion of the waste toner container 11 in the mounting direction, and a cartridge side transmission unit 23 for controlling reading and writing of information to and from the memory 22. The cartridge side transmission unit has a function of transmitting data to be transmitted to the memory 22, writing to the memory 22, or reading from the memory 22. The cartridge side transmission unit 23 and the memory 22 are integrated on the substrate and are mounted on the cartridge C. When the cartridge C is mounted on the main body of the image forming apparatus, the cartridge side transmission unit 23 and the main body side transmission unit 14 on the image forming apparatus main body side are arranged so as to come into contact with each other at the opposing positions. The main body side transmission unit 14 functions as a transmission unit on the main body side of the image forming apparatus, and is connected to a main body control unit 24 of the main body of the image forming apparatus.

  The memory used in the present invention can be used without particular limitation as long as it is an electronic memory using a normal semiconductor. For example, EEPROM, FeRAM or the like can be used as the memory.

  The above description is a case where the cartridge-side transmission unit 23 and the main body-side transmission unit 14 are in contact to establish a data communication path to perform read / write data communication. You can also. In that case, an antenna member (not shown) for communicating with electromagnetic waves may be provided on each of the cartridge side and the image forming apparatus main body side to perform communication.

  The cartridge side transmission unit 23, the main body side transmission unit 14, and the main body control unit 24 can read and write information in the memory 22. It is assumed that the memory 22 has a capacity sufficient to store a plurality of pieces of information such as a cartridge usage amount and a cartridge characteristic value described later.

  In addition, the usage amount information of the cartridge C is written and stored in the memory 22 as needed. The cartridge usage information stored in the memory 22 is not particularly limited as long as it can be determined by the main body of the image forming apparatus. For example, the rotation time of each unit such as the photosensitive drum 1, the charging roller 2, and the developing sleeve 5, the bias application time to the charging roller 2, the developing sleeve 5, etc., the remaining amount of toner, the number of prints, and the image dots that are formed on the photosensitive member Number, integrated value of laser emission time when exposing the photoconductor, film thickness of the photoconductor, a value obtained by weighting each usage amount, a value calculated using each usage amount, etc. Is mentioned.

  Further, the characteristic value of the cartridge corresponding to the individual characteristic of the cartridge at the time of shipping the cartridge is a parameter for changing the process conditions at the time of image formation, and is stored in the memory 22 at the time of shipping from the factory. As the parameter, for example, an appropriate value is stored depending on the production lot of the photosensitive drum, the electrical characteristic value of the charging roller, the contact pressure of the cleaning blade, and the like.

  Based on these pieces of information stored in the memory 22, process conditions are controlled by the main body control unit 24. That is, the information in the memory 22 is read by the main body control unit 24 via the cartridge side transmission unit 23 and the main body side transmission unit 14, and is calculated using the information in the main body control unit 24, and a process is performed based on the calculation result. Change the conditions.

  In this embodiment, cartridges having different film thicknesses of photosensitive drums and different toner capacities are used as different types of cartridges that can be attached to and detached from the same image forming apparatus main body.

First, the latent image characteristics of the photosensitive drum depending on the film thickness of the photosensitive layer of the photosensitive drum will be described.
Since the photosensitive drum has different electrostatic capacities depending on the film thickness of the photosensitive layer, when a predetermined exposure amount is applied to the photosensitive drum having the same dark portion potential (−600 V), the bright portion potential is the film thickness. It depends on the thickness. FIG. 3 shows the transition of the bright portion potential with respect to the exposure amount when the film thickness of the photosensitive layer is 40 μm and 30 μm. As the film thickness decreases, the bright portion potential increases in a region where the laser power on the drum surface in FIG. 3 is small and the exposure amount is near 2.0 mJ / m ² . That is, in a halftone image such as a halftone, the density varies depending on the film thickness of the photosensitive drum. Thus, it can be seen that the density fluctuates even when the same image is formed due to the difference in the film pressure of the photosensitive layer of the photoreceptor.

  When several types of cartridges having different film pressures of the photosensitive drum can be mounted on the same image forming apparatus main body, it is desirable that the same image density be obtained when image formation is performed using all the different types of cartridges. It is necessary to optimize the bright portion potential regardless of the drum film thickness difference.

FIG. 4 shows the transition of the bright portion potential when the dark portion potential is lowered by changing the DC voltage of the charging bias in the photosensitive drum having a photosensitive layer thickness of 30 μm. As can be seen from the comparison with FIG. 3, by reducing the dark part potential for a thin photosensitive drum, the bright part potential becomes close to the transition of the bright part potential of 40 μm, and halftone and other halftones are obtained. The image density can be made substantially the same. Accordingly, by setting the laser power on the drum surface to 2.5 to 3.5 mJ / m ² to a bright part potential with a solid density, the halftone density and solid density difference due to the film thickness difference of the photosensitive layer can be reduced. Can do.

  However, if the dark portion potential is lowered too much, the difference from the development potential (back contrast) becomes small, so that the density increases even with the same development contrast, and the amount of toner flying to the white background portion called fog increases. Therefore, it is necessary to finely adjust the DC voltage of the developing bias so that the density and fog are in appropriate ranges, thereby increasing the back contrast.

  As another means, it is possible to adjust the light exposure potential by adjusting the exposure amount of the laser.

From FIG. 3, when the light portion potential is set to −160 V with an exposure amount of 2.7 mJ / m ^{2 in} the initial film thickness of 40 μm, the exposure is 3.1 mJ / m ² when the film thickness is 30 μm. By setting the amount, the same bright portion potential is obtained, and the difference in halftone potential can be reduced.

Next, changes in development characteristics that may occur due to different toner volumes will be described.
FIG. 5 shows the transition of the line width of a 4 dot (resolution 600 dpi setting) line corresponding to the usage amount (number of prints) of the photosensitive drum in an S cartridge corresponding to 5000 sheets and an L cartridge corresponding to 10000 sheets. Here, it is assumed that the S and L cartridges are different only in toner capacity.

  In the initial stage of use, both the S and L cartridges have the same line width transition, but after that, the line width of the S cartridge having a short life is larger than that of the L cartridge having a long life. In the L cartridge having a long life, the line width tends to be thicker than that of the S cartridge, but in the latter half of the life, it tends to be thick up to the same width of 200 μm as the S cartridge.

  When the toner capacity is small, the toner circulation is good due to stirring by the stirring member, etc., so that the toner is charged faster overall, and the toner is supplied to the developing unit as compared with the case where the toner capacity is large. Occasionally, the toner rises up to an appropriate charge amount, and developability increases. Therefore, because of the development characteristics of the S cartridge, the S cartridge has a larger change in line width than the L cartridge. On the other hand, the L cartridge with a large toner capacity has a slower toner charge rise, so the line width is smaller than that of the S cartridge, and the change in the line width increases as the amount of residual toner in the developing container decreases.

  As described above, since the development characteristics differ depending on the amount of filled toner, it is preferable to stabilize the developability by performing control according to the difference in toner amount.

  As the means, there are methods of changing the AC or DC voltage of charging and developing bias, and adjusting the laser exposure amount.

  In addition, in order to perform control for stabilizing the developability, it is possible to use the cumulative number of dots of image information for an image formed on the photosensitive drum capable of estimating the toner consumption amount, or print. It is possible to use the number of cartridges and the amount of cartridge used based on the time and coefficient information of the cartridge that will be described later. It may be controlled to adjust the charging, developing bias, and laser exposure amount at the timing when the cumulative number of dots of image information, the number of prints, and the cartridge usage amount reach a predetermined value (predetermined threshold information).

In this embodiment, in order to adjust the difference in latent image characteristics and development characteristics according to the type of cartridge described above, the following control is performed using information relating to the amount of cartridge used.
(1) The cartridge C includes a memory 22 and stores information related to the type of cartridge.
(2) The memory 22 stores the time when the cartridge C is driven in the image forming apparatus main body. (3) Coefficient information of an arithmetic expression determined by the contact pressure between the photosensitive drum 1 and the cleaning blade 10 and the electrical characteristics of the charging roller 2 and threshold information as timing for switching process conditions are stored in the memory 22 at the time of manufacture. deep.
(4) In the main body of the image forming apparatus, the type of the cartridge is identified, and the amount of use of the cartridge C (for example, the amount of use of the photosensitive drum 1) is calculated based on the drive time and coefficient information stored in the memory 22 of the cartridge C. The calculated value is compared with the threshold information relating to the use amount, which is stored in the memory 22 of the cartridge C and determined in advance according to the characteristics of the photosensitive material of the photosensitive drum 1. Then, the process condition is changed when the calculated value reaches the threshold value.

  Here, a plurality of threshold information stored in the memory 22 of the cartridge C may be set, and the exposure amount and the charging / developing bias may be switched a plurality of times. This makes it possible to obtain a stable bright portion potential throughout the usage period of the photosensitive drum 1, and to realize high image quality (stabilized image quality) of the formed image. In addition, the threshold information may be stored in the memory 22 of the cartridge together with information regarding the setting of the process condition to be changed.

The configuration of the characteristic part in the present embodiment will be specifically described with reference to FIGS.
In this embodiment, the photosensitive drum usage information calculated based on the photosensitive drum rotation time is used as the information related to the cartridge usage. This corresponds to the usage amount of the photosensitive drum calculated based on the damage index of the photosensitive drum disclosed in Japanese Patent No. 3285785.

  As shown in FIG. 6, the main body control unit 24 includes a data storage memory 13, a control unit 25, a calculation unit 26, a photosensitive member rotation instruction unit 27, a charging bias application time detection unit 28, a main body transmission unit 14, and the like. , Connected to a bias supply power source 29. Further, the cartridge C is provided with a memory 22 and a transmission unit 23.

  Further, as shown in FIG. 7, the memory 22 in the cartridge C has cartridge drive time information T, drum usage calculation formula coefficient information φ, which is a weighting coefficient for calculating the photosensitive drum usage, and photosensitive drum usage threshold. Information such as information α and information indicating a table for setting image forming conditions corresponding to photosensitive drum usage threshold information is stored. Note that the drum usage threshold information α and the drum usage calculation formula coefficient information φ are stored in the memory 22 when the cartridge C is shipped. Since these values vary depending on the drum sensitivity, drum material, contact pressure of the cleaning blade, and electrical characteristics of the charging roller, each cartridge C is stored in a memory and shipped.

Next, the control operation of this embodiment will be described.
When the main body of the image forming apparatus receives the print signal, the cartridge C is driven by the photosensitive member rotation instruction unit 27, and the image forming process is started. At this time, the drum usage is calculated as follows.

  A value B obtained by integrating photosensitive drum rotation time data (corresponding to the cartridge driving time information T) from the photoconductor rotation instruction unit 27, and a value A obtained by integrating charging bias application time data from the charging bias application time detection unit 28. The calculation unit 26 calculates the drum usage D by the conversion formula D = A + B × φ using the weighting coefficient φ read from the memory 22 and accumulates and stores it in the main body memory 13 for main body data storage. The accumulated drum use amount D is compared with the threshold value α in the memory 13 in the main body of the image forming apparatus by the calculation unit 26. As a result of the comparison, when the drum usage D becomes larger than the threshold value α, a control signal is sent from the control unit 25 to a high voltage circuit unit (not shown) in the bias supply power supply unit 29 to change the DC voltage of the charging / developing bias. Is done.

  The photosensitive drum rotation time data and the charging bias application time data are stored in the memory 22 as needed, and the calculation of the drum usage amount data is performed as needed when the driving of the photosensitive drum 1 is stopped.

  Instead of storing the photosensitive drum rotation time data and charging bias application time data in the memory 22, the calculated drum usage D may be written in the memory 22.

  In this embodiment, a plurality of tables, each of which is a set of a plurality of process conditions considering the latent image characteristics of the photosensitive drum depending on the film thickness of the photosensitive drum and the development characteristics depending on the toner capacity, are provided. The process conditions are set by selecting one from a plurality of tables according to the usage status.

As a combination of process conditions in this embodiment,
(1) Exposure amount and charging / development bias Mainly controlled by latent image characteristics: exposure amount, development characteristics: charging / development DC voltage. Alternatively, control is performed using latent image characteristics: charging / developing DC voltage and developing characteristics: exposure amount.
(2) Only charging / developing bias: latent image characteristics and development characteristics: both are controlled by charging and developing DC voltage.
Is possible.

  The combination of the process conditions will be described in detail in order.

(Embodiment 1)
In the case of controlling by the exposure amount and the charging / developing bias, an example will be given in the following cartridge C in which the toner capacity and the photosensitive layer thickness of the photosensitive drum are different.
S cartridge; toner capacity equivalent to 5000 sheets (5% printing), photosensitive layer thickness 30 μm
L cartridge; equivalent to 10,000 toner capacity (5% printing), photosensitive layer thickness 40 μm
In the latent image characteristics, the exposure amount can be switched in four stages as shown in Table 1 depending on the consumption amount of the photosensitive layer, and in the development characteristics, the charging DC voltage development DC voltage can be switched in three stages.

  Regarding the switching between the charging DC voltage and the developing DC voltage, when density adjustment is performed by changing the DC voltage of charging and developing bias as shown in FIG. 8, not only the default setting value (density setting value) but also its upper limit (density) The three types shown in Table 2 including the voltage settings for the dark side and the lower limit (low concentration side) were prepared.

  As described above, the table of seven combinations as combinations of exposure amount, charging DC voltage, and development DC voltage setting as shown in Table 3 from the transition of density and line width due to differences in latent image characteristics and development characteristics of S and L cartridges. Prepared.

  Here, the wear speed (wear level) of the photosensitive drum according to the number of sheets passed was confirmed. As a result, both the S and L cartridges were 1 μm / 1000 sheets in the 1 sheet / job mode.

And the drum usage is one sheet print,
A value A = 10 obtained by integrating charging bias application time data,
Value B = 5 obtained by integrating photosensitive drum rotation time data,
The weighting coefficient φ = 2, and the drum usage D per sheet print D = 20 (10 + 5 × 2).

  From these, the table for selecting and setting the threshold information α as shown in FIG. 9 is determined from the wear amount of the photosensitive drum depending on the number of sheets to be passed and the development characteristics.

  FIG. 9A shows the switching timing of the table of Table 3 and the table setting to be selected, and FIG. 9B shows detailed information of the switching timing. As shown in FIG. 9A, in order to select different tables at different timings for the S cartridge and the L cartridge and set the process conditions, the storage contents of the memory provided in the S cartridge and the L cartridge are as shown in FIG. It becomes a structure as shown in.

Storage areas S01 to S10 and L01 to L12 are set in the memories provided in the S cartridge and the L cartridge, respectively. The stored contents are as follows. S01, L01: Cartridge type information S02 indicating whether the cartridge is an S cartridge or L cartridge, L02: Rotating time information of the photosensitive drum when printing is performed using the cartridge, S03, L03: Charging means (printing roller when printing is performed using the cartridge) 2) Application time information S04, L04 when charging bias is applied: Calculation coefficient information S05, L05: Information indicating that the cartridge is not used S06, L06: Process conditions at the beginning of cartridge use For setting the value (value in Table 3)
S07, S09, L07, L09, L11: Photosensitive drum usage threshold information (switches process conditions when the photosensitive drum usage reaches this threshold information)
S08, S10, L08, L10, L12: Information for selecting a process condition corresponding to the usage amount of the photosensitive drum (the values in Table 3 are stored corresponding to the threshold information).

  Although the cartridge configuration of the S cartridge and the L cartridge is the same, as described above, the toner capacity and the film thickness of the photosensitive drum are different. The S cartridge has a toner capacity equivalent to 5000 sheets (A4: 5% printing), the film thickness of the photosensitive drum is 30 μm, and the L cartridge has a toner capacity equivalent to 10,000 sheets (A4: 5% printing), a photosensitive drum. The film thickness is 40 μm.

  Then, as shown in FIG. 9, the process conditions (exposure conditions, charging / developing conditions) are changed in accordance with the usage amount of the photosensitive drum in each cartridge.

Next, the operation of the image forming apparatus of this embodiment will be described with reference to the flowcharts of FIGS.
START: Start of control S101: The image forming apparatus main body is turned on.
S102: Recognize the type of cartridge C in which the control unit 24 of the main body is mounted. (Information stored in the storage area S01 of the memory 22 (L01 in the case of an L cartridge) is read to recognize either the S cartridge or the L cartridge, and for example, the type of cartridge is displayed on the operation panel of the image forming apparatus main body. Etc.)
S103: Next, unused information indicating whether or not the cartridge is unused is read from the storage area S05 of the memory 22, and if it is indicated that the cartridge is not used, the information indicating that the information has been used. Update to Then, information c for setting process conditions at the start of use is read from the storage area S06 of the memory 22. This c is the data in the table shown in Table 3. In this case, the process condition corresponding to c is set as the process condition at the start of use. Note that c is stored in the memory 13 as a value at the start of cartridge use. S104: The main body control unit 24 reads the threshold information αsi stored in the storage area S07 of the memory 22 (L07 in the case of the L cartridge), and stores the read threshold information in the memory 13 of the control unit 24. (The initial value of i is 1)
S105: The integrated value information of the photosensitive member rotation time and charging bias application time so far is read from the storage areas S02 and S03 of the memory 22 of the cartridge C (L02 and L03 in the case of the L cartridge).
S106: After that, the image forming apparatus is in a print ready state (a state in which a print signal can be received) and is waiting to receive a print signal.
S107: Print signal ON.
S108: The photoconductor rotation time detection unit 27 starts counting the rotation time and integrates it with the photoconductor rotation time read from the memory 22.
S109: The charging bias application time detector 28 starts counting the charging bias application time and integrates it with the charging bias application time read from the memory 22.
S110: End of printing.
S111: The weighting coefficient φ is read from the storage area S04 of the memory 22 of the cartridge (L04 in the case of the L cartridge).
S 112: The calculation unit 26 calculates the drum usage D using the photosensitive drum rotation time and charging bias application time accumulated in S 108 and S 109 and the weighting coefficient φ read from the memory 22.
S113: The threshold information αsi is read from the memory 13 in the main body control unit 24.
S114: The calculator 26 compares the drum usage data D with the drum usage calculation threshold value αsi. That is, it is determined whether D> αsi. If “YES” is determined, the process proceeds to S115. If “NO” is determined, the process returns to step S105 to repeat the control.
S115: The table setting value d corresponding to the drum usage amount threshold value αs1 is read from the storage area S08 (L08 in the case of the L cartridge) of the memory 22 of the cartridge, and the process is performed based on the table setting value d in Table 3. The conditions (exposure amount, charging / developing DC voltage) are switched. Here, the value of c stored in the memory 13 in S103 is rewritten and stored in this d value. (The memory 13 is rewritten every time the set value is switched.)
S116: Set i = i + 1, return to S106, and repeat the control.

In each of the S and L cartridges, an image having a printing rate of 2% was printed under the condition of 1 sheet / job, and the image was evaluated for each predetermined number of sheets. (Number of prints: 0 to 15000)
FIG. 11 is a density transition in a halftone image formed at an isolated 1 dot and having a printing rate of 25%. FIG. 12 shows the transition of 4 dot (resolution 600 dpi setting) line width. It was confirmed that high-quality images without fogging were obtained, showing a stable halftone density and line width throughout the life, without any difference in cartridge type.

  A halftone image with a printing rate of 25% is printed every 1000 prints to check the density transition, and an image with a 4-dot line width is printed every 1000 prints to check the line width change.

  Further, the table values (a to g) selected in accordance with the drum usage amount of each of the S cartridge and the L cartridge are set independently for the S cartridge and the L cartridge. The values in the same table may be set depending on the film thickness, toner capacity, density corresponding to the film thickness, and the transition state of the line width. For example, c = f may be set in the table setting.

The threshold information for switching the table is also independent for the S cartridge and the L cartridge, but the amount of photoconductor drum wear may be the same for both the S and L cartridges (though it may be different). The table setting selection switching may be performed with the same threshold information.
Since the configuration of the cartridge C in FIG. 16 has been described above, the description thereof will be omitted.

(Embodiment 2)
Control only by charging / developing bias In this embodiment, the latent image characteristics and development of different types of cartridges are switched by switching the DC voltage setting of the charging / developing bias including the upper limit and lower limit setting as described in the first embodiment. Suppresses fluctuations in density and line width due to differences in characteristics.

  The cartridge C used in the present embodiment has the same configuration as the cartridges S and L in the first embodiment, but the information stored in the memory 22 of each cartridge is different.

  In this embodiment, the DC voltage of the charging bias is reduced so that the latent image potentials are the same based on the threshold information of the drum usage amount corresponding to the film thickness of the photosensitive layer of the photosensitive drum. Then, the DC voltage of the developing bias is set to be small so that the back contrast can be secured to some extent so as not to cause fogging in accordance with the change of the DC voltage of the charging bias. As the setting of the charging bias DC voltage and the developing bias DC voltage, three kinds of settings including the upper limit and the lower limit of density as shown in Table 4 (tables (I) to (III)) are prepared.

  The developing characteristics are corrected by changing the density default setting value (density setting value) in the DC setting of the charging / developing bias selected from (I) to (III) in Table 4. . For example, as shown in FIG. 13, the setting of the bias from the upper limit to the lower limit can be selected in 10 stages. The normal default setting (density setting) is 5; however, for example, when the line is narrow due to development characteristics, the DC voltage setting of 3 on the higher density side is set. The developability is stabilized by allowing selection.

  As described above, a table comprising six combinations of DC voltage setting and density default setting (density setting) as shown in Table 5 is prepared based on changes in latent images of S and L cartridges, density and line width due to differences in development characteristics. did. As described above, the voltage density setting was selected from set values that were uniformly distributed over a period of 0 to 10, with the upper limit (higher density side) setting being 0 and the lower limit (lower density side) setting being 10.

  For example, in the S cartridge, the density default setting (density setting) of the DC voltage of the charging / developing bias is as shown in Table 6.

  When the drum usage amount reaches the threshold information αs1, the table setting is changed from j to k in order to suppress an increase in the line width due to an increase in toner developability due to the development characteristics of the S cartridge in FIG. The setting is switched, and the density default setting (density setting) is changed from 5 to 7 in the same DC setting (II).

  When the drum usage reaches the threshold information αs2, the table setting is switched from k → l. In order to correct the latent image characteristic mainly due to the reduction in the photosensitive layer thickness of the photosensitive drum, the DC setting in (III) is switched, and the density default setting (density setting) is used to finely correct the line width variation. Was set to 6.

Thus, in order to correct the latent image characteristics of the cartridge and to ensure the back contrast according to the amount of photosensitive drum used, the charging bias and developing bias DC voltage tables (I) to (III) are set. In each table, the default value of the density setting value is set to be changed in order to correct the development characteristics.
Then, when the control as shown in FIG. 14 was performed at the same switching timing as shown in FIG. 9B, the same effect as in Example 1 was obtained.

  FIG. 17 shows the configuration of the contents stored in the memory 22 of each of the S and L cartridges in this embodiment. The configuration of the storage area is substantially the same as the configuration of the first embodiment (FIG. 16), but the value of the threshold information α (storage areas S05, S07) and the set values (storage areas S06, S08) stored corresponding thereto. , S10, L06, L08, L10, L12) are different from the first embodiment.

The control of the image forming operation in the present embodiment is the same as the control shown in the flowchart of FIG.
Note that the configuration of the cartridge C in FIG.

  In the first embodiment and the second embodiment, as shown in FIGS. 16 and 17, the photosensitive drum rotation time information and the charging bias application time information are separately updated and stored. However, the present invention is not limited to this, and the photosensitive drum rotation time information and the charging bias application time information are not stored separately, but the usage amount information of the photoconductor calculated using the photosensitive drum rotation time information and the charging bias application time information. The same effect can be obtained in the configuration in which (D) is updated and stored.

  As described above, according to this embodiment, even when a plurality of types of cartridges having different photosensitive drum thicknesses and filled toner capacities are used in the same image forming apparatus main body, variations in density and line width are reduced. It becomes possible to do. In other words, by performing different process control at the same photosensitive drum usage timing, it is possible to suppress variations in image quality due to the difference in type, especially variations in density and line width, and to stabilize image quality from the start of use to the end of its service life. Can be made.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Exposure apparatus 4 Development apparatus 4a Development container 5 Development sleeve 6 Cleaning apparatus 7 Development control member 8 Stirring member 9 Transfer roller 10 Cleaning blade 11 Waste toner container 12 Fixing apparatus 13 Memory 14 Main body side transmission part 18 Resist Roller 20 Paper feed cassette 21 Paper feed roller 22 Memory C Process cartridge P Transfer material t Toner

Claims (9)

Select a first cartridge and a second cartridge in which the initial amount of toner stored in the developer storage unit storing toner for forming a toner image on the image carrier is larger than that of the first cartridge An detachable image forming apparatus,
The first cartridge or the second cartridge includes a storage medium for storing identification information for identifying the first cartridge and the second cartridge, and the identification information and use of the cartridge A control unit that selects an image forming condition from a plurality of settings for setting the image forming condition based on information on the amount;
In the case where the amount of use of the cartridge is the same, the control unit performs the image formation using the first cartridge rather than the image formation using the second cartridge. and the light portion potential of the electrostatic latent image formed on the carrier, it is possible to control the potential difference the smaller the developing DC voltage applied to the developing means for developing the electrostatic latent image into a toner image, and non The electrostatic latent image formed on the image carrier is brighter when image formation is performed with the used first cartridge than when image formation is performed with the unused second cartridge. An image forming apparatus characterized in that a potential difference between a partial potential and a developing DC voltage applied to a developing means for developing the electrostatic latent image into a toner image is reduced .   The first cartridge and the second cartridge are provided with the image carrier, and the first cartridge and the second cartridge are provided with the image carrier having different characteristics. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the image carrier is a photoconductor, and the image carrier having different characteristics is a photoconductor having a different thickness of a photosensitive layer of the photoconductor. .   4. The photosensitive member according to claim 3, wherein the first cartridge includes a photosensitive member having a thin photosensitive layer, and the second cartridge includes a photosensitive member having a thick photosensitive layer. The image forming apparatus described.   The storage medium further stores threshold information on the usage amount of the cartridge, and the control unit is based on the threshold information, the identification information, and information on the usage amount of the cartridge. The image forming apparatus according to claim 2, wherein an image forming condition is set from the plurality of settings. Furthermore, the first cartridge and the second cartridge have charging means for charging the image carrier,
The image forming apparatus according to claim 5, wherein the threshold value information includes any one of a rotation time of the image carrier and a bias application time to the charging unit. The image carrier is a photoreceptor;
The first cartridge and the second cartridge have charging means for charging the image carrier, and developing means for developing a latent image formed on the photoconductor,
7. The plurality of settings includes information relating to a bias applied to the charging unit or the developing unit or an exposure amount for forming a latent image on the photosensitive member. The image forming apparatus according to any one of the above.   The control unit makes an initial exposure amount when the unused first cartridge is mounted larger than an initial exposure amount when the unused second cartridge is mounted. The image forming apparatus according to claim 7. The storage medium further stores calculation coefficient information,
The image forming apparatus according to claim 1, wherein the control unit calculates a usage amount of the cartridge using the calculation coefficient information.

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