JP2001265177A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device, capable of distinguishing the life of a latent image carrier and the service life developer. SOLUTION: A control part is constituted to decide the service lives of a photoreceptor drum and the developer not only on the basis of 'Vsg0-Vsgp' which is detected result of the toner amount adhering to the surface part of the photoreceptor drum but also by considering VT being the detected result of the toner concentration TC of the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.
The present invention relates to an image forming apparatus that determines the life of at least one of the latent image carrier and the developer based on the amount of a developing substance adhered per unit area on the latent image carrier such as a photoconductor.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, for example, an image is formed by the following process. That is, first, an electrostatic latent image is carried on a latent image carrier that has been uniformly charged by a charging means such as a charging charger or a charging roller by performing exposure processing by laser irradiation or the like. Then, a potential difference (developing potential) is generated between the electrostatic latent image and the developing device such that a developing substance such as toner is electrostatically moved and adhered from the developing device toward the electrostatic latent image. The leverage electrostatic latent image is developed. Next, the developed image obtained by the development is transferred to a recording medium such as transfer paper directly or via an intermediate transfer member to obtain a transfer image. Then, the developing material remaining on the photoreceptor after the transfer is cleaned by mechanically scraping with a cleaning blade.

In an image forming apparatus for forming an image by such a process, the charging ability of a latent image carrier is reduced by repeated charging, exposure, and cleaning.
The latent image carrier is gradually deteriorated, for example, by abrasion of the surface layer. When the latent image carrier is deteriorated in this manner, various problems occur, such as causing the background material (non-latent image portion) to adhere to a developing substance due to insufficient charging of the latent image carrier and causing background contamination. It is necessary to replace the carrier with a new one.

Therefore, in Japanese Patent Application Laid-Open No. Hei 4-60651, the amount of toner adhering to the background of a photoreceptor serving as a latent image carrier is detected by an optical sensor. 2. Description of the Related Art There has been proposed an image forming apparatus that determines that the life of a body is reached.

On the other hand, when a so-called two-component developer containing a magnetic carrier and a toner as a developing substance is used as a developer, the two-component developer is repeatedly rubbed in a developing device to remove the two-component developer. Deteriorate gradually. Deterioration in this way causes various problems, such as soiling caused by the phenomenon of so-called spent, which causes the toner to fuse to the surface of the magnetic carrier. Therefore, it is necessary to replace the two-component developer with a new one.

In Japanese Patent Application Laid-Open No. Hei 5-80655, the amount of toner adhering to the background of a photoreceptor is detected by an optical sensor. An image forming apparatus for determining has been proposed.

[0007]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 4-60651, when the background contamination due to the deterioration of the two-component developer occurs, the photosensitive member can still be sufficiently used. In spite of the above, an erroneous determination is made that "it is the life of the photoconductor". Then, there is a problem that this erroneous determination prompts the user to replace the photosensitive drum wastefully.

In Japanese Patent Application Laid-Open No. Hei 5-80655, when background contamination occurs due to deterioration of the photosensitive member, the two-component developer is still in a state where it can sufficiently withstand use. However, there is a problem in that the user is erroneously determined to be "the life of the two-component developer" and the user is urged to replace the developer wastefully.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus capable of distinguishing between the life of a latent image carrier and the life of a developer. That is.

To achieve the above object, the present invention is directed to a latent image carrier for carrying an electrostatic latent image, a charging means for charging the latent image carrier, and a developing device. A developing device that uses a developer containing a substance and a carrier to develop the electrostatic latent image by attaching the developing material, a developing bias control unit that controls a developing bias of the developing device,
At least one of the latent image carrier and the developer based on the amount of the developer attached to the background of the latent image carrier; An image forming apparatus, comprising: a replenishing unit for replenishing the developer with a developing material; and a developing material adhering amount to a reference image developed on the latent image carrier. Supply control means for controlling the driving of the replenishing means, density detecting means for detecting the concentration of the developing substance of the developer, and potential detecting means for detecting the potential of the latent image carrier. Means for developing the electrostatic latent image for the reference image at a predetermined developing potential based on an output from the potential detecting means for detecting the potential of the electrostatic latent image for the reference image. Control and the life span It is characterized in that the constant means determining 該寿 life also based on developing agent concentration.

In this image forming apparatus, "determining the life" means determining whether or not the life has been reached, or whether or not the life is about to be reached.

In this image forming apparatus, when the developing material gradually adheres to the carrier surface with the deterioration of the developer (when the spent begins to occur), the frictional force between the carrier surface and the developing material is reduced. The chargeability of the carrier with respect to the developing substance is reduced. Then, due to this decrease, the charge amount of the developing material such as toner decreases. When the charge amount of the developing material is reduced in this way, the electrostatic latent image for the reference image is developed at a predetermined developing potential,
The amount of developing substance attached to the reference image obtained by development (reference image density) increases. For this reason, when the charge amount of the developer decreases, the replenishment control means reduces the replenishment amount of the developer to the developer to reduce the developer concentration of the developer, thereby increasing the reference image. The concentration is reduced to a predetermined concentration. When the welding of the developing substance to the carrier surface further proceeds, such a decrease in the amount of charge of the developing substance and a decrease in the concentration of the developer substance are repeated, and finally, a background stain is generated. Therefore, the developer concentration of the developer when background contamination due to the deterioration of the developer occurs is significantly lower than the developer concentration of the developer in a state where the developer is not deteriorated.
On the other hand, for example, when the charging ability of the latent image carrier is partially or entirely reduced due to the deterioration of the latent image carrier, the potential of the background portion of the latent image carrier in the reversal developing method is different from the charging polarity of the developing material. Background dirt is generated due to, for example, an increase in the reverse polarity side. However, in the process of generating such background contamination, the electrostatic latent image for the reference image is developed at a predetermined developing potential even if the charge amount of the latent image carrier is reduced. For this reason, even if the latent image carrier deteriorates, the reference image density does not change so much unless the developer deteriorates, and the replenishment control means does not greatly reduce the developer concentration of the developer.
Therefore, in the present image forming apparatus, when the background contamination due to the deterioration of the developer occurs, the background contamination due to the deterioration of the latent image carrier while the developer concentration of the developer is lower than the predetermined concentration. If this occurs, the concentration of the developing substance will remain at or exceed the predetermined concentration. Therefore,
The life determining means detects the occurrence of background contamination based on the amount of the developing substance adhered to the background portion of the latent image carrier, and takes into account the detection result of the developer concentration of the developer, taking into account the detection result of the developer concentration. It is configured to determine the life of the device. In such a configuration, when the occurrence of background contamination is detected based on the detection result of the amount of the developer attached to the background portion of the latent image carrier, it is taken into consideration whether or not the concentration of the developing substance at this time is lower than a predetermined concentration. This makes it possible to make a distinction between the life of the latent image carrier and the life of the developer.

Incidentally, the deterioration of the latent image carrier can be caused by abrasion of its coat layer, a decrease in charging ability, a decrease in charge holding ability, etc. There is a type in which the image density is reduced due to a reduction in latent image potential due to a reduction in photosensitivity and the like.
That is, there is also a deterioration of the latent image carrier of a type that does not generate background contamination. As for the deterioration of the developer, there is a type that causes background contamination due to spent and a type that causes carrier adhesion to the latent image carrier due to abrasion of the coat layer of the carrier. That is, there is also a deterioration of the type of developer that does not generate background contamination. With the present image forming apparatus, it is possible to detect, among the above-mentioned deteriorations, the deterioration of the latent image carrier and the developer of the type that generates background contamination, but can detect the deterioration of the type that does not generate the background contamination. Can not.
Further, the background image soiling of the latent image carrier includes those caused by deterioration of the latent image carrier and the developer, and those caused by other factors such as contamination of the charging unit and the latent image carrier exposing unit. . In the present image forming apparatus, the life of the latent image carrier and the developer may be erroneously determined based on the background stain generated due to such other factors.

Therefore, according to a second aspect of the present invention, in the image forming apparatus of the first aspect, an operation number obtaining means for obtaining the number of image forming operations is provided, and the life is determined based on the number of image forming operations. The above-mentioned life determining means is configured.

In the image forming apparatus of the first aspect, since the latent image carrier and the developer gradually deteriorate with the use thereof, a certain degree of difference exists between the degree of deterioration and the number of image forming operations. A correlation is established. The image forming apparatus according to the second aspect determines the life of the latent image carrier and the developer by taking into account the number of image forming operations having such a correlation. In such a configuration, in addition to detecting the deterioration of the latent image carrier and the developer of the type that generates background contamination, the type of background contamination that does not generate background contamination can be detected based on the number of image forming operations. Will be possible. In addition, when the number of image forming operations has not reached the predetermined number of times when the background contamination is detected, the background contamination may be caused by another factor different from the deterioration of the latent image carrier and the developer. It becomes possible to determine. As a result, the accuracy of determining the life of the latent image carrier and the developer can be improved.

However, when detecting the deterioration of the latent image carrier or the developer that does not generate background contamination based on the number of image forming operations, it is determined that a non-degraded state is deteriorated, In addition, there is a possibility that erroneous detection may occur such that a deteriorated state is determined to be not deteriorated.
This is because there is no strict correlation between the number of image forming operations and the degree of deterioration of the latent image carrier and the developer.

According to a third aspect of the present invention, there is provided the image forming apparatus of the first or second aspect, wherein the life of the developer is determined as the life. The life determining means is configured to determine the life based on an activity variable.

In this image forming apparatus, the "activity variable of the developing device" is an integrated value of the operating time of the developing device or the supply time of the developing bias, or the integrated value of the operating time, the supplying time of the developing bias, or the developing bias. Properties (voltage value,
Current value, duty, AC / DC state, etc.).

In the image forming apparatus according to the second aspect, the degree of deterioration of the developer when the predetermined number of image forming operations has been reached is determined by the operation time, the developing bias supply time, and the property of the developing bias up to that time. It depends on the differences. For this reason, the deterioration degree of the developer shows a better correlation with the activity variable of the developing device than the number of image forming operations. According to the image forming apparatus of the present invention, the life of the developer is determined in consideration of the activity variables of the developing apparatus having a good correlation with the degree of deterioration of the developer, and thus the accuracy of the life determination is improved. It can be further improved.

According to a fourth aspect of the present invention, in the image forming apparatus of the first, second or third aspect, the life of the latent image carrier is determined as the life. The present invention is characterized in that arithmetic means is provided, and the life determining means is configured to determine the life based on the activity variable.

In this image forming apparatus, the "activity variable of the latent image carrier" refers to the integrated value of the operating time, charging time or exposure time of the latent image carrier, or the operating time, the charging time, This is a concept showing an integrated value of a numerical value obtained by multiplying at least two of the exposure time, the charge application amount at the time of charging, or the exposure intensity.

In the image forming apparatus according to the second aspect, the degree of deterioration of the latent image carrier when a predetermined number of image forming operations is reached differs depending on a difference in the operation time and charging time of the latent image carrier. . Generally, the operation time and charging time of the latent image carrier per one image forming operation are not constant. For example, these times during a so-called continuous copy operation and during a single copy operation (operation when only one document is copied). ) Is different from these times. Even when these times are the same, the degree of deterioration of the latent image carrier differs depending on the difference in the accumulated charge amount of the latent image carrier. Specifically, the degree of deterioration increases as the accumulated charge amount increases. Therefore, the degree of deterioration of the latent image carrier shows a better correlation with the activity variable of the latent image carrier than the number of image forming operations. The image forming apparatus according to claim 4 determines the life of the latent image carrier by taking into account the activity variables of the latent image carrier having a good correlation with the degree of deterioration of the latent image carrier as described above. The accuracy of determining the life can be further improved.

According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the life of the latent image carrier is determined based on a detection result of the potential of the latent image carrier by the potential detecting means. And the above-mentioned life determining means.

The latent image carrier deteriorates and causes development such as a reduction in charging ability, charge holding ability, and photosensitive ability, and an increase in residual charge. These phenomena are solved by the latent image carrier of the latent image carrier. And its occurrence can be detected based on the detection result of the potential of the ground portion. Therefore, in the image forming apparatus of the present invention, the development is detected based on the output from the potential detecting means, and the life of the latent image carrier is determined in consideration of the detection result. The accuracy of determining the life can be further improved as compared with the image forming apparatus.

According to a sixth aspect of the present invention, the life of the latent image carrier and the life of the developer are determined as the life.
The image forming apparatus according to any one of 2, 3, 4, 5, and 6, further comprising a stirring means for stirring the developer, and when it is determined that the life of the developer has been reached, the development of the latent image is stopped. After the stirring means is driven for a predetermined time under the conditions described above, the life of the developer is determined again.

In the image forming apparatus according to the first aspect, if background stains caused by the deterioration of the latent image carrier and background stains caused by the deterioration of the developer occur at the same time, the background damage is caused only by the latter deterioration. The developer concentration of the developer is lower than a predetermined concentration, as in the case where stains occur. In such a case, only the deterioration of the developer can be detected, although the deterioration of the latent image carrier actually occurs. On the other hand, in the image forming apparatus according to the sixth aspect, when the deterioration of the developer is detected based on the occurrence of background contamination, the developer is stirred for a predetermined time by the stirring means, and then the life of the developer is determined again. I do. Then, at the time of this determination, the presence or absence of background contamination is detected again based on the amount of the developing substance attached to the background portion of the latent image carrier. At the time of this re-detection, if the deterioration of the latent image carrier and the deterioration of the developer occur simultaneously, the background dirt is detected again, whereas if only the deterioration of the developer occurs, the background is not detected. Dirt is no longer detected. Background fouling due to the deterioration of the developer is caused by insufficient charge of the developing material.
This is because immediately after the developing material is charged by stirring, no background stain is generated. Therefore, in the present image forming apparatus, it is determined whether only the developer reaches the end of life or both the latent image carrier and the developer reach the end of life based on the presence or absence of background contamination after stirring. It becomes possible to determine.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a digital printer (hereinafter, referred to as a printer) as an image forming apparatus will be described. First, a basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. In the figure, a scorotron charger 2 as a charging unit, a laser writing device as an exposure unit (not shown), and a developing device are provided around an organic photoconductor drum (OPC: hereinafter, referred to as a photoconductor drum) 1 as a latent image carrier. 3, a transfer device 4, a cleaning device 5, an optical sensor 7 as an adhesion amount detecting unit, a potential sensor 18 as a potential detecting unit for detecting a surface potential of the photosensitive drum 1, and the like.

Further, the printer includes a CPU 101, an RA
The control unit 100 includes an M102, a ROM 103, and the like. The CPU 101, which is a calculating means, has an A / D
The optical sensor 7 is connected via a converter 8. A power pack 9 for supplying power to the scorotron charger 2 is provided with a PWM 1 for adjusting an output voltage of the power pack 9.
0. Further, a drive motor 11 for driving a toner supply roller 3e described later is connected to the motor via a motor driver 12 for supplying a drive power to the drive motor. A power pack 13 for supplying a developing bias to developing rollers 3a and 3b, which will be described later, is connected via a PWM 34 for adjusting the output voltage of the power pack 13.

In this printer, the photosensitive drum 1 is rotated clockwise in the figure at a constant speed during printing by drum driving means such as a motor (not shown). After being charged to -900 [V] (grid bias VG = -1000 [V]) by the charging output current of the scorotron charger 2 and the grid bias, the laser writing device responds to the image signal by the laser writing device. The writing light L modulated and controlled in this way is irradiated and imaged. By this irradiation image, -100 [V] is applied on the photosensitive drum 1.
Is formed. This electrostatic latent image moves to a developing position which is a position facing the developing device 3 with the rotation of the photosensitive drum 1. The charging output current of the scorotron charger 2 and the grid bias are adjusted so that the potential detection value of the potential sensor 18 becomes a predetermined value.

The developing device 3 includes developing rollers 3a, 3
b, a stirring paddle 3f as stirring means for stirring a two-component developer (not shown) composed of toner and magnetic carrier, a magnetic permeability sensor (hereinafter referred to as a T sensor) for outputting a voltage having a value corresponding to the magnetic permeability of the two-component developer. And 3) a developing unit including 3c and the like. Further, a toner replenishing roller 3e for feeding replenishing toner to the developing unit and a hopper 3d for storing replenishing toner are provided. Stir paddle 3
f stirs a two-component developer (hereinafter simply referred to as a developer) included in the developing unit to rub the toner and the magnetic carrier, thereby charging the toner to a negative polarity. Each of the developing rollers 3a and 3b includes a magnet roller (not shown), and carries the developer stirred by the stirring paddle 3f on the surface by the magnetic force of the magnet roller. These developing rollers 3a and 3b are respectively supplied with -550 by the power pack 13.
A developing bias VB of [V] is applied. +450 [V] (−100 − (− 550)) is applied between the surfaces of the developing rollers 3 a and 3 b to which the developing bias VB is applied and the electrostatic latent image on the surface of the photosensitive drum 1. A development potential occurs. Further, −35 is provided between the surfaces of the developing rollers 3 a and 3 b and the background portion of the surface of the photosensitive drum 1.
A development suppression potential (background potential) of 0 [V] (-900-(-550)) is generated. The value of the developing bias is determined by the control unit 100 that controls the PWM 14.
Is controlled by the PWM 14
The developing bias control means is constituted by the combination of the control unit 100 and the control unit 100.

The photosensitive drum 1 moved to the developing position
On the surface, a negative toner is electrostatically attached to the electrostatic latent image by the action of the developing potential. Further, by the action of the development suppression potential, toner adhesion to the background portion is electrostatically suppressed. As a result, at the developing position, the toner is adhered to the electrostatic latent image on the photosensitive drum 1 and the toner image is N / P (negative / positive).
Developed. The toner image developed in this manner moves to a transfer position, which is a position facing the transfer device 4, as the photosensitive drum 1 rotates.

The transfer device 4 includes a drive roller 4 that is driven to rotate counterclockwise in the figure by a drive mechanism (not shown).
a, a rotatable driven roller 4b, a belt stretched by these rollers, a transfer roller 4 that contacts the back surface of the belt and presses the belt against the photosensitive drum 1
c etc. This belt forms a transfer nip by being pressed against the photosensitive drum 1 by the transfer roller 4c, and moves endlessly counterclockwise in the figure with the rotation of the drive roller. A transfer bias is supplied to the transfer roller 4c from a power supply (not shown), and a transfer electric field (not shown) is formed in the transfer nip by the transfer bias (positive polarity). A pair of registration rollers is disposed on the right side of the transfer device 4 in the figure, and transfers transfer paper sent from a paper supply device such as a paper cassette (not shown) to the photosensitive drum 1 at the transfer nip. At a timing such that the toner image is superimposed on the belt. The transferred transfer paper is
The toner image enters the transfer nip and is superimposed on the toner image, and the toner image is transferred by a synergistic effect such as a pressing force at the transfer nip and an electrostatic force of the transfer electric field. Then, after being discharged from the transfer nip, it is discharged to the outside of the printer via a fixing device (not shown).

The cleaning device 5 has a cleaning roller 5a. The cleaning device 5 is moved left and right by a moving device (not shown) to move the cleaning roller 5a toward and away from the photosensitive drum 1. A cleaning bias (positive polarity) is applied to the cleaning roller 5a by a power source (not shown). When the cleaning roller 5a rotates while being in contact with the photosensitive drum 1, residual toner remaining on the surface of the photosensitive drum 1 is removed. It is electrostatically attached and removed by the action of the cleaning bias. Then, the toner is scraped off from the surface of the cleaning roller 5a by the cleaning blade in contact with the cleaning roller 5a and collected.

When the electrostatic latent image on the photosensitive drum 1 is developed, the toner in the developer is consumed accordingly,
The toner concentration of the developer decreases. For this reason, the control section 100 performs toner density control for appropriately supplying toner from the hopper section 3d to the developing section by driving the toner supply roller 3e. Specifically, the control unit 10
0 is the reference VTr which is the output target of the T sensor 3c.
The data of f is stored in the ROM 103. When the development of the electrostatic latent image is completed, the T sensor 3
c is obtained from the output voltage value VT.
ΔVT, which is the difference between VTref and the reference VTref, is calculated. There is a correlation between the magnetic permeability of the developer and the toner density, and the toner density decreases as the magnetic permeability increases. Therefore, the output voltage value VT of the T sensor 3c decreases as the toner concentration TC of the developer increases. Further, the toner density TC of the developer is lower than the target density as the value of ΔVT which is a solution of “VTref−VT” increases to the negative side. The controller 100 can determine the toner concentration TC based on the value of ΔVT. Therefore, in the present printer, the density sensor is constituted by the combination of the T sensor 3c and the control unit 100. The sensitivity of the T sensor 3c is calibrated so that an output voltage of 1.5 to 3.5 [V] is obtained at a toner concentration TC of 3.5 to 1.5 [wt%].

When the controller 100 determines that the toner concentration of the developer is lower than the target concentration based on the calculation result of ΔVT, the controller 100 supplies a toner supply time t (driving time of the motor 7c) according to ΔVT. ). Then, based on the determined toner supply time t, the drive motor 11 is driven to supply a necessary amount of toner to the hopper section 3.
d to replenish the developing unit. By supplying a necessary amount of toner to the developing section of the developing device 3 in this manner, the toner concentration TC of the developer in the developing section is kept substantially constant. However, the developing performance of the developing device 3 depends on the toner density TC.
In addition, since the toner image is affected by the environment such as temperature and humidity, it is not possible to maintain the density of the developed image constant simply by keeping the toner concentration TC constant. Therefore, the control unit 100 appropriately corrects the toner concentration TC to be kept constant, that is, the reference VTref, based on the amount of toner adhered to the reference toner image formed on the photosensitive drum 1, and It is configured to perform reference density correction control for maintaining performance at a constant.

In the reference density correction control, the control unit 1
00 firstly forms a reference toner image on the photosensitive drum. Specifically, the control unit 100 is also connected to a laser driving driver for controlling the driving of the laser writing device (not shown), a drum driving unit (not shown) for driving the photosensitive drum 1, and the moving device for moving the cleaning device. The control unit 100 outputs a control signal to these to control the formation of the electrostatic latent image. Then, by controlling the driving of each device, a patch-like electrostatic latent image is formed on the non-transfer paper corresponding area of the photosensitive drum 1 at a predetermined timing, for example, every time ten transfer papers are printed out. Then, based on an output signal from the potential sensor 18 for detecting the potential of the patch-like electrostatic latent image, the developing bias is set so that the developing potential of the patch-like electrostatic latent image becomes +280 [V]. While controlling, the patch-like electrostatic latent image is developed by the developing device 3 to obtain a reference toner image.

When such reference image formation control is performed, the moving device is controlled so that the cleaning device 5 is separated from the photosensitive drum 1, so that the formed reference toner image is not cleaned. I do. Therefore, the formed reference toner image reaches a position facing the optical sensor (hereinafter, referred to as a P sensor) 7 without being removed from the photosensitive drum 1 by the cleaning device 5. Then, the light reflectance is detected by the P sensor 7. As the light reflectance on the photosensitive drum 1 increases, the toner adhesion amount M / A on the photosensitive drum 1 decreases, and the output voltage value from the P sensor 7 decreases.

After the control unit 100 forms the reference toner image, the P sensor 7 detects the light reflectance of the reference toner image.
And the output voltage value Vsp from the RAM 1
Vsp / Vsg0, which is the ratio with the output voltage value Vsg0 from the P sensor 7 relating to the background portion stored in 02, is calculated. The Vsg is applied to the surface of the photosensitive drum 1 at a predetermined timing, for example, immediately after a printer main power supply (not shown) is turned on.
The light reflectance is detected by the P sensor 7 while the cleaning is performed, and is acquired. As a result, the light reflectance of the photosensitive drum 1 without toner adhesion is obtained.

After calculating the above Vsp / Vsg0, the control unit 100 determines the density of the reference toner image based on the calculation result. Further, based on this determination result and the value of the output voltage value VT from the T sensor 3c at that time, a correction amount ΔVTref for the reference VTref used so far is determined to correct the reference VTref.
By such correction, the developing performance of the developing device 3 is kept almost constant regardless of the environmental fluctuation.

The control unit 100 is configured to execute a life determination control for judging the life of the photosensitive drum 1 and the life of the developer in parallel with the above-described reference density correction control. That is, the control unit 100 has a function as a life determination unit. In this life determination control, first, the output voltage value Vsgp from the P sensor 7 is obtained. This Vsgp is the output voltage value from the P sensor 7 immediately before or immediately after the detection of the reference toner image, that is, the output voltage value from the P sensor 7 that detects the uncleaned background portion of the photosensitive drum 1. . This Vsgp when soiling occurs on the photoreceptor drum 1 is, of course, Vsg0
Smaller than. Therefore, the control unit 100 sets Vsg0
When the difference between Vsgp and Vsgp exceeds a predetermined value, it is determined that the photosensitive drum 1 is soiled and that the life of the photosensitive drum 1 or the developer has expired. When such a determination is made, a message such as "Replace the photosensitive drum because it has reached the end of its life." Is displayed on a display unit (not shown) such as a liquid crystal display. The control unit 1 of the printer
00 is configured to determine that the life of the photosensitive drum 1 or the developer has reached when the conditional expression “Vsg0−Vsgp <0.2 [V]” is not satisfied.

Next, the characteristic structure of the printer will be described. In the present printer, when the spent starts to occur due to the deterioration of the developer, the chargeability of the magnetic carrier to the toner decreases. Then, due to this decrease, the charge amount of the toner decreases. When the charge amount of the toner is reduced in this way, the amount of toner attached to the reference toner image increases despite the fact that the patch-like electrostatic latent image is developed at a predetermined development potential. For this reason, the control unit 100, which is a supply control unit,
The toner concentration TC is gradually reduced. Therefore, the toner density T at the time when background contamination due to the deterioration of the developer occurs
C is much lower than the toner concentration TC in a state where the developer is not deteriorated. On the other hand, if the charging capability of the photosensitive drum 1 is partially or entirely reduced as the deterioration of the photosensitive drum 1 progresses, even if the charging output current of the scorotron charger 2 and the grid bias are considerably increased, the photosensitive drum 1
Is partially or totally lacking in the background
Overall background stains and granular background stains occur. However, since the patch-like electrostatic latent image is developed at a predetermined developing potential, the output voltage value Vsp of the P sensor 7 (the amount of toner adhering to the reference toner image) changes significantly even if such background contamination occurs. do not do. For this reason, the photosensitive drum 1
If the developer does not deteriorate even if the toner concentration deteriorates, the toner concentration TC of the developer does not significantly decrease. In view of the above phenomena, the control unit 100 is configured to perform the life determination control as shown in FIG.

In the life judging control shown in FIG.
0, first, after acquiring the above Vsg0 (step 1, hereinafter, the step is referred to as s), the printing operation is started (s2). Next, after obtaining the above Vsgp and the above VT (toner concentration TC) (s3, s4), "Vsg
It is determined whether or not the conditional expression “0−Vsgp <0.2 [V]” is satisfied (s5). And when it is determined that it is provided (Y in s5), no background dirt has occurred,
It is determined that both the photosensitive drum 1 and the developer have not reached the end of their lives, and the control ends. If it is determined that the condition is satisfied (N in s5), it is next determined whether or not the conditional expression “VT <4V” is provided. If it is determined that the condition is satisfied (Y in s6), the toner density is determined. It is determined that the background dirt does not reduce TC so much, that is, the background dirt due to the deterioration of the photoconductor drum 1, and the display unit displays the photoconductor life, and the control is terminated (s7). Further, when it is determined that the developer is not provided (N in s6), it is determined that at least background contamination due to the deterioration of the developer is generated, and s8 described later is used.
To s14.

In the control from s8 to s14, first, after the above-mentioned Vsg0 is obtained again (s8), the developer is stirred by the stirring paddle 3f for a predetermined time under the condition that the toner supply is turned off (s9). . When the amount of toner charge is insufficient due to this stirring,
The toner is charged to a normal charge amount. Next, after acquiring the above Vsgp again (s11), “Vsg0−V
sgp <0.2 [V] ”,
That is, it is determined whether or not soiling still occurs (s
11). When it is determined that the toner is provided (Y in s11), that is, when it is determined that the background is not generated, the background is generated only due to the insufficient toner charge amount, that is, the developer Is determined to be caused only by the deterioration of the agent, and the life of the agent is displayed on the display section (s1).
2). In addition, when it is determined that it is not provided (N in s11), that is, when it is determined that soiling has occurred again,
It is determined that the background contamination has occurred due to the deterioration of both the photosensitive drum 1 and the developer, and the display unit displays the photosensitive member life and the agent life (s13, s14).

According to this printer, the life of the photosensitive drum 1 and the life of the developer can be distinguished and determined by such life determination control.

Next, the printer of each embodiment will be described. [First Embodiment] FIG. 3 is a flowchart showing the life determination control of the printer according to the first embodiment. This life determination control
First, the point that the control of s3a and s3b is performed between s2 and s3 is different from the life determination control of FIG. These s
In the control of 3a and s3b, the integrated value of the number of prints, which is the number of image forming operations, is calculated. More specifically,
A calculation is performed of an integrated value mk of the number of prints from the time when the photosensitive drum 1 is replaced to the present time and an integrated value mz of the number of prints from the time when the developer is replaced to the present time. Then, immediately after the control in s6, the control in s6a is performed prior to the control in s7. This s
In the control of 6a, it is determined whether or not the conditional expression “mk> 360,000 sheets” is provided. If it is determined that the conditional expression is provided, the control in and after s7 is executed. On the other hand, if it is determined that the photoconductor drum 1 and the developer have not been provided, it is determined that deterioration of the photosensitive drum 1 and the developer is caused by other factors, and the control is terminated.

It is determined between s11 and s12 whether or not the conditional expression "mz> 300,000 sheets" is satisfied. If the conditional expression is satisfied, the control after s12 is executed, and If not, it is determined that the background contamination has occurred and the deterioration of the developer is caused by other factors, and the control is terminated.

It is determined between S11 and s13 whether or not the conditional expression “mk> 360,000 sheets” is satisfied. If so, the control after s13 is executed (however, If not, control is terminated because it is determined that the background contamination that has occurred is caused by other factors in the deterioration of the photosensitive drum 1 if not provided (step S13).

According to the printer of the first embodiment, it is determined by the above-described life determination control whether background dirt is caused by a factor different from deterioration of the photosensitive drum 1 and the developer. As a result, the accuracy of determining the life of the photosensitive drum 1 and the developer can be improved.

[Second Embodiment] FIG. 4 is a flowchart showing the life determination control of the printer according to the second embodiment. This life determination control is performed between s4 and s5 by s4a and s4b.
Is different from the life determination control shown in FIG. In the control of s4a and s4b, the control unit 1
0 acquires the potential Vd of the background portion of the photosensitive drum 1 based on the output from the potential sensor 18. And
It is determined whether or not the conditional expression “Vd ≦ 850 [V]” is provided. If it is determined that the conditional expression is not provided, (s6b
N), the control ends assuming that the usage time of the photosensitive drum 1 and the developer is relatively short, and that these deteriorations have not progressed so much.

When the replacement time of the photosensitive drum 1 and the replacement time of the developer are different, the control of s4b is not performed between s4 and s5 but between s6 and s7.
It is desirable to provide between s11 and s12. Then, it is desirable to execute the following life determination control. That is, between s6 and s7, the control of s6b is performed to determine whether or not the conditional expression “Vd ≦ 850 [V]” is provided. When it is determined that the conditional expression is not provided, (at s6b N), the control ends assuming that the usage time of the photosensitive drum 1 is relatively short and the deterioration thereof has not progressed so much. Also, between s11 and s12, it is determined whether or not the conditional expression “Vd ≦ 850 [V]” is provided. If it is determined that the conditional expression is not provided (N in s11c), the photosensitive drum 1 It is assumed that the use time is relatively short and the deterioration has not progressed so much, and only the agent life is displayed on the display section.

According to the printer of the second embodiment, the accuracy of determining the life of the photosensitive drum 1 can be further improved by such a life determination control.

In the second embodiment, if the life of the photosensitive drum 1 is determined based on the cumulative charging time and the cumulative charging amount of the photosensitive drum 1 instead of Vd, the system for determining the life can be further increased. Can be improved.

[0052]

According to the invention of claim 1, 2, 3, 4, 5 or 6, there is an excellent effect that the life of the latent image carrier and the life of the developer can be determined separately. .

In particular, according to the invention of claim 2, there is an excellent effect that the accuracy of determining the life of the latent image carrier and the developer can be improved.

In particular, according to the invention of claim 3, there is an excellent effect that the accuracy of determining the life of the developer can be further improved.

In particular, according to the invention of claim 4, there is an excellent effect that the accuracy of determining the life of the latent image carrier can be further improved.

In particular, according to the invention of claim 5, there is an excellent effect that the accuracy of determining the life of the latent image carrier can be further improved as compared with the invention of claim 4.

In particular, according to the invention of claim 6, it is possible to determine whether only the developer has reached the end of its life or whether both the latent image carrier and the developer have reached the end of its life. There is an excellent effect that it can be done.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printer according to an embodiment.

FIG. 2 is a flowchart showing life determination control of the printer.

FIG. 3 is a flowchart illustrating life determination control of the printer according to the first embodiment.

FIG. 4 is a flowchart illustrating life determination control of the printer according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 2 scorotron charger 3 developing device 3c T sensor 4 transfer device 5 cleaning device 7 P sensor 100 control unit

Continued on front page F term (reference) 2H027 DA02 DA10 DA15 DA45 DD07 DE05 DE07 EA05 ED09 ED10 HB01 HB13 HB14 2H077 AA15 AB03 AD06 AD35 DA01 DA03 DA20 DA47 DA52 DA57 DA78 DA80 DB02 DB25 EA03 FA19 9A001 HH34 KK35 KK15 KK15 KK15

Claims (6)

[Claims] An electrostatic latent image is developed by using a latent image carrier for carrying an electrostatic latent image, charging means for charging the latent image carrier, and a developer containing a developing substance and a carrier. A developing device that develops by applying a substance, a developing bias control unit that controls a developing bias of the developing device, an adhesion amount detecting unit that detects an amount of a developing material adhered on the latent image carrier, and the latent image carrier A life determining means for determining the life of at least one of the latent image carrier and the developer based on the amount of the developing material adhered to the background portion of the image forming apparatus. Replenishing means for replenishing, replenishing control means for controlling the driving of the replenishing means based on the amount of developing substance adhered to the reference image developed on the latent image carrier, and density for detecting the developing substance concentration of the developer Detecting means and the latent image carrier Potential detecting means for detecting the potential of the body, the developing bias control means, based on an output from the potential detecting means for detecting the potential of the electrostatic latent image for the reference image, for the reference image An image forming apparatus, wherein the developing bias is controlled so that an electrostatic latent image is developed at a predetermined developing potential, and the life determining means determines the life based on the concentration of the developing substance. 2. The image forming apparatus according to claim 1, further comprising an operation number obtaining unit for obtaining the number of image forming operations, wherein said life determining unit is configured to determine the life based on the number of image forming operations. An image forming apparatus comprising: 3. The image forming apparatus according to claim 1, wherein the life of the developer is determined as the life. An integrating operation means for calculating an activity variable of the developing device is provided. An image forming apparatus, wherein the life determining means is configured to determine a life. 4. The image forming apparatus according to claim 1, wherein the life of said latent image carrier is determined as said life, wherein integration means for calculating an activity variable of said latent image carrier is provided.
An image forming apparatus, wherein the life determining means is configured to determine the life based on the activity variable. 5. The image forming apparatus according to claim 4, wherein said life determining means determines the life of said latent image carrier based on a detection result of said potential of said latent image carrier by said potential detecting means. An image forming apparatus comprising: 6. The image forming apparatus according to claim 1, wherein the life of the latent image carrier and the life of the developer are determined as the life. When it is determined that the life of the developer has been reached, the stirring means is driven for a predetermined time under the condition that the development of the latent image is stopped, and then the life of the developer is determined again. An image forming apparatus.