JP2001147630A - Electrophotographic image forming device and cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly obtain a picture having a stable density without unnecessary consumption of developer when restarting the image forming operation after stopping it. SOLUTION: The latest time of image formation is stored in a memory 20 provided in the image forming device main body, and image forming processing is started after a development sleeve 4a and a developer supply roll 4b are driven for a prescribed time in accordance with the length of the time calculated by the difference between this stored time and the present time. Toner of which the charge amount is reduced by leaving the toner till reception of a next image forming processing instruction after the end of preceding image forming processing is charged by the development sleeve 4a and the developer supply roll 4b if necessary, and thus an image having a stable density is obtained without unnecessary toner consumption.

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 an electrophotographic copying machine, a facsimile, a printer, and the like, and a cartridge detachable from the electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic method, a change in an environment in which the image forming apparatus is used,
In order to prevent the image density from fluctuating greatly due to various conditions such as the number of prints, a toner image for density detection (hereinafter referred to as a “patch”) is provided on a photoconductor drum as an electrophotographic photoconductor.
Is formed, and the toner density of the toner image is detected by an optical sensor or the like serving as density detecting means, and the detected toner density is fed back to image forming conditions such as a developing bias, which is a developing process condition, so that the image density becomes a predetermined density. 2. Description of the Related Art An image forming apparatus that performs image density control so as to maintain the image density is known.

In the above image density control, first, when the image density control is started, an image density control circuit serving as an image density control means provided in the image forming apparatus transmits an image representing a patch from a pattern generation circuit. A signal is generated, and based on the signal, n
A latent image is formed for each of the patches P1 to Pn. Next, the latent image is developed by a developing device. At this time, the patches P1 to Pn are developed with different developing biases V1 to Vn by switching a developing bias (VDC) for each patch by a high-voltage control circuit. The densities D1 to Dn of the patches P1 to Pn created on the photosensitive drum are measured by the density sensors.

When the latent image of the density detection patch is developed with different development biases V1 to Vn, the relationship (V−D) between the development bias (VDC) and the patch density (OD) is obtained.
D characteristic) is as shown in FIG. As is apparent from FIG. 5, the VD characteristic is obtained by the portions A and C where the characteristic does not change much.
And a portion B whose characteristics are largely changed. In addition, the VD characteristic varies depending on the environment in which the image forming apparatus is installed, and has a characteristic as shown in FIG. 6, for example. In FIG. 6, the characteristic a is the same as that of FIG. 5, the characteristic b is the one in a high temperature and high humidity environment, and the characteristic c is
Are those in a low-temperature and low-humidity environment.

[0005] As shown in FIG. 5, in the VD characteristics, the density change is unstable in the portions A and C, and the density is stably increased in the portion B. Therefore, as shown in FIG. 6, during the density control, the control target DTarget is set to B
, And the densities D1 to Dn of the patches are D1 <
D2 <... <Di <Di + 1 <... <Dn, and the control target density DTarget is approximately halfway between the densities D1 to Dn.
Are set in such a manner that the developing biases V1 to Vn are satisfied.
The values of the developing biases V1 to Vn are set such that the control target density DTarget falls within the range of D1 to Dn even if the VD characteristics slightly change and the values of the densities D1 to Dn change. The interval w between the developing bias Vi and the developing bias Vi + 1 shown in the figure is set to about 50V.

As described above, since the VD characteristic greatly varies depending on the environment, if the values of the developing biases V1 to Vn are fixed as shown in FIGS. It goes out of the range of D1 to Dn. Therefore, the developing biases V1 to Vn are also changed according to the respective environments, so that the control target density DTarget becomes the density D1 to D1.
Dn is set to be approximately in the middle. For example, as shown in FIG.
4 is used to control the image density.

When the image density control is started, the developing biases V1 to Vn are determined according to the absolute water content in the apparatus calculated from the temperature and humidity sensors provided in the image forming apparatus.
The one suitable for the image density control at that time is selected. Then, by using the density D1 to Dn of each patch measured by the density sensor and the data of the developing bias V1 to Vn when the patch was created, the image density control circuit optimally obtains the control target density DTarget. The developing bias VTarget is calculated.

The method for calculating the optimum developing bias VTarget is as follows. First, a section in which the control target density DTarget is included among the patch densities D1 to Dn, that is, Di ≦
A section (i to i + 1) in which DTarget ≦ Di + 1 is searched.
If such a section is found, a developing bias VTarget for obtaining DTarget using linear interpolation is used.
Is calculated.

VTarget = {(Vi + 1−Vi) / (Di + 1−Di)} (DTarget−Di) + Vi (1) The optimum developing bias VTarget is calculated by the following equation (1).

Then, the developing bias VTarget is stored in a memory as a storage means, and an image is formed using this value until the next image density control is executed.

The image density control described above is performed when the power of the image forming apparatus main body is turned on or when the doors of the respective parts are opened.
This is executed when a change in image forming conditions is expected, such as every fixed number of prints or every certain time interval. Particularly in the case of a color image forming apparatus, Y (yellow), M (magenta),
Since it is necessary to perform the processing independently for each of the colors C (cyan) and K (black) and it takes a considerable time, the response to the image output request may be delayed. Also, if the image density control is executed even when the image forming conditions are not particularly changed, for example, after a short power-off, the user will needlessly wait, and the toner used for creating the patch will be wasted. Will be.

Therefore, in order to prevent such unnecessary image density control from being executed, the time when the power of the image forming apparatus is turned off is recorded in a non-volatile memory built in the cartridge, and the power is reset. Japanese Patent Application Laid-Open No. H11-218972 proposes to determine whether or not to execute the image density control based on the length of the apparatus stop time at the time of feeding.

[0013]

However, since the stop time of the image forming apparatus is a continuous numerical value and does not suddenly change from a state where image density control is not required to a state where image density control is required, the stop time of the image forming apparatus is simply reduced. It is not always possible to quickly obtain an image with a stable density by only two types of measures, whether or not to execute the control. Hereinafter, this point will be described in detail.

In an electrophotographic image forming apparatus, V
The -D characteristic varies depending on the driving state of the device as well as the environment in which the device is installed. For example, while the image forming apparatus is stopped, the charge amount of the toner decreases as shown by c ′ in FIG. 8, and the VD curve shifts to a lower density side. If the stop time of the image forming apparatus is short, it is not necessary to execute density control because the shift is very small. Conversely, after a long-term stop, V
The shift of the −D curve becomes too large, and as a result, the control target density DTarget may be out of the range of the densities D1 to Dn, which may cause an error. If the VD curve further shifts due to overlapping conditions such as toner durability deterioration, the possibility of occurrence of an error is further increased.

When such an error occurs, it is necessary to perform processing such as selecting a default developing bias preset as a value of the developing bias VTarget. The default development bias is, for example, V1 and V
intermediate value of n, or V1, D if DTarget <D1
If n <DTarget, it is a value such as Vn.

In this case, only a minimum image is guaranteed, and an image having a stable density cannot be obtained. In order to suppress such a situation as much as possible, the developing biases V1 to Vn
It is conceivable to extend the range of the developing bias that can be controlled by increasing the interval w or by increasing the number of patches. However, the method of increasing the interval of the developing bias increases the error when performing linear interpolation, The method of increasing the number of patches has a problem that the amount of consumed toner increases.

Further, the reduction of the charge amount and the shift of the VD curve while the image forming apparatus is stopped are temporary, and when the image forming process is restarted, the state quickly recovers to a steady state. Therefore, the VTarget determined based on the temporary shift of the VD curve in the image density control at the time of resuming the image formation becomes an inappropriate value with the recovery of the charge amount, and an image having a stable density is obtained. You won't get it. In order to suppress such a situation as much as possible, a method of setting the image density control execution interval to be short and finding an appropriate VTarget following the recovery process of the charge amount can be considered. However, image density control is frequently performed. There is a problem that toner consumption increases.

Accordingly, an object of the present invention is to provide an electrophotographic image forming apparatus capable of rapidly obtaining an image having a stable density without wasting developer when the image forming operation is restarted after the image forming operation is stopped. An object of the present invention is to provide an apparatus and a cartridge to be mounted on the electrophotographic image forming apparatus.

[0019]

The above object is achieved by an electrophotographic image forming apparatus and a cartridge according to the present invention. In summary, the present invention relates to an electrophotographic image forming apparatus for forming an image on a recording medium, wherein (a) an electrophotographic photosensitive member and (b) an electrostatic latent image is formed on the electrophotographic photosensitive member. (C) a developing device for developing the electrostatic latent image formed on the electrophotographic photoreceptor; and (d) a first time storing means for storing a first time. ,
(E) a second time different from the first time and the first time;
Determining means for determining an image forming operation to be executed based on the first time stored in the time storage means.

According to a second aspect of the present invention, there is provided an electrophotographic image forming apparatus for detachably mounting a cartridge and forming an image on a recording medium, comprising: (a) an electrophotographic photosensitive member; Mounting means for removably mounting a cartridge having a developing device for developing the electrostatic latent image formed on the photoreceptor; and (b) first time storage means for storing a first time (C) determining means for determining an image forming operation to be executed based on a second time different from the first time and the first time stored in the first time storage means. An electrophotographic image forming apparatus is provided.

According to a third aspect of the present invention, there is provided a cartridge detachably mountable to an electrophotographic image forming apparatus main body.
(A) an electrophotographic photoconductor, and (b) a developing device for developing an electrostatic latent image formed on the electrophotographic photoconductor,
(C) first time storage means for storing a first time, wherein the determination means provided in the electrophotographic image forming apparatus main body executes based on the first time and the second time. A cartridge is provided which determines an image forming operation to be performed.

In one embodiment of the present invention, the first time is a time when an image was last formed, and the second time is a current time.

According to another embodiment of the present invention, the developing device includes a charging member for charging a developer, and the determining unit determines the timing based on the first time and the second time. The time for operating the charging member in advance before starting the developing process is determined.

According to another embodiment of the present invention, the electrophotographic image forming apparatus executes image density control at a predetermined interval, and the determining unit determines the image density based on the first time and the second time. The execution interval of the image density control is changed to a value different from the predetermined interval.

According to another embodiment of the present invention, there is further provided image forming means for forming a reference pattern image on the electrophotographic photosensitive member under a plurality of different process conditions, and detecting the density of the reference pattern image. Density detecting means, and image density controlling means for determining a process condition for executing predetermined image density control based on the density detection result, wherein the determining means determines the first time and the second time. A process condition for forming the reference pattern image is changed based on time.

According to another embodiment of the present invention, there is further provided an image forming means for forming a reference pattern image on the electrophotographic photosensitive member under a plurality of different process conditions, and detecting the density of the reference pattern image. Density detecting means, and image density controlling means for determining a process condition for performing predetermined image density control based on the density detecting result, wherein the determining means is configured to determine the first time and the second time The number of the reference pattern images is changed based on the above.

According to another embodiment of the present invention, the cartridge further includes at least one of a charging unit for charging the electrophotographic photosensitive member and a cleaning unit for cleaning the electrophotographic photosensitive member. Have.

[0028]

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

Embodiment 1 A first embodiment of the present invention will be described.

The electrophotographic image forming apparatus of the present embodiment is shown in FIG.
As shown in FIG. 1, a photosensitive drum 1 serving as a drum-shaped electrophotographic photosensitive member on which an electrostatic latent image is formed on an outer peripheral surface, and a photosensitive drum 1
A roller charger 2 serving as a charging unit for charging the outer peripheral surface of the electrostatic latent image to a specified potential, an exposure device for forming an electrostatic latent image on the outer peripheral surface charged to the specified potential by exposure, and developing the electrostatic latent image A developing device 4 for forming a visible image with toner as a developer, a roller-shaped transfer roller 3 for transferring a visible image (visible image) formed on the outer peripheral surface to a transfer paper P as a sheet-shaped recording medium, and a fixing device 5 It has.

In FIG. 1, a photosensitive drum 1 has an organic photosensitive member (OPC) or an organic photosensitive member (OPC) on the outer peripheral surface of an aluminum cylinder.
It is constituted by applying a photoconductor made of A-Si, CdS, Se, or the like, and is rotationally driven in a direction indicated by an arrow in FIG. Be charged.

The exposing device is disposed above the main body of the image forming apparatus, and includes a laser diode 7, a polygon mirror 9, which is driven to rotate by a high-speed motor 8, a lens 10, and a folding mirror 11.

When an image signal is input to the laser driver 12, the laser driver 12
To emit light. Then, the light from the laser diode 7 passes through the optical path 13 and irradiates the photosensitive drum 1 with optical information corresponding to the image signal, so that a latent image is formed on the photosensitive drum 1.

Further, when the photosensitive drum 1 advances in the direction of the arrow, the bias power supply 14 supplies the frequency 80 between the photosensitive drum 1 and the developing sleeve 4a provided in the developing device 4.
A latent image is developed by applying a developing bias composed of a DC voltage and an AC voltage, which is composed of 0 to 3500 Hz, an amplitude of 400 to 3000 V, and an integrated average value of the waveform VDC of -50 to -550 V. It becomes an image.

The toner visible image developed in this manner is transferred onto the transfer paper P by the transfer roller 3 to which a predetermined bias is applied. Then, the transfer paper P on which the toner image has been transferred is transported by transporting means (not shown),
The toner image is fused and fixed by the fixing device 5 to become a permanent image.

The toner remaining on the photosensitive drum 1 is cleaned by a cleaning device 6 including, for example, a fur brush and blade means.

In the above-mentioned image density control, when the image density control is started, the image density control circuit 19 as the image density control means provided in the image forming apparatus is switched from the pattern generation circuit 15 as the image forming means. An image signal representing a patch which is a toner image for density detection is generated, and a latent image for n patches P1 to Pn is formed along the rotation direction on the photosensitive drum 1 based on this signal.

Next, the latent image is developed by the developing device 4. At this time, the developing bias (VDC) is switched for each of the patches P1 to Pn by the high-voltage control circuit 16 so that the developing bias V1 is different from each other. ~ Vn
Is developed. Then, the densities D1 to Dn of the patches P1 to Pn formed on the photosensitive drum 1 are measured by the density sensors 17 as density detecting means.

As described above, when the latent image of the density detecting patch is developed with different developing biases V1 to Vn, the developing bias (VDC) and the patch density (O.D.
D. ) Is as shown in FIG. 5 described above. As is clear from FIG. 5, the VD characteristic is composed of portions A and C where the characteristic changes little and a portion B where the characteristic changes greatly. In addition, the VD characteristic varies depending on the environment in which the image forming apparatus is installed, and has a characteristic as shown in FIG. 6, for example. In FIG.
The characteristic a is the same as that in FIG. 5, the characteristic b is under a high-temperature and high-humidity environment, and the characteristic c is under a low-temperature and low-humidity environment.

As shown in FIG. 5, in the VD characteristic,
In the portions A and C, the change in concentration is unstable, and in the portion B, the concentration is stably increasing. Therefore, as shown in FIG. 6, at the time of the density control, the control target DTarget is set to the portion B, and the densities D1 to Dn of the patches are D1 <D2.
<... <Di <Di + 1 <... <Dn, and the developing biases V1 to Vn are set such that the control target density DTarget is approximately halfway between the densities D1 to Dn. Even if the VD characteristic fluctuates slightly and the values of the densities D1 to Dn fluctuate, the values of the developing biases V1 to Vn vary even if the densities D1 to Dn fluctuate.
et is set to a value that falls within the range of D1 to Dn, and the developing bias Vi and the developing bias Vi shown in FIG.
The distance w from +1 is set to about 50V.

As described above, since the VD characteristic greatly varies depending on the environment, if the values of the developing biases V1 to Vn are fixed as shown in FIGS. It goes out of the range of D1 to Dn. Therefore, the developing biases V1 to Vn are also changed according to the respective environments, so that the control target density DTarget becomes the density D1 to D1.
Dn is set to be approximately in the middle. For example, as shown in FIG.
4 to control the image density.

When the density control is started, the developing biases V1 to Vn are changed according to the absolute water content in the apparatus calculated from the temperature / humidity sensor 18 provided in the image forming apparatus.
The one suitable for the image density control at that time is selected. The image density control circuit 19 obtains a control target density DTarget by using the density D1 to Dn of each patch measured by the density sensor 17 and the data of the developing bias V1 to Vn when the patch was created. The optimum developing bias VTarget is calculated.

As described above, the method for calculating the optimum developing bias is as follows. First, a section in which the control target density DTarget is included among the densities D1 to Dn, ie, Di ≦
A section (i to i + 1) in which DTarget ≦ Di + 1 is searched.
If such a section is found, a developing bias VTarget for obtaining DTarget using linear interpolation is used.
Is calculated.

VTarget = {(Vi + 1−Vi) / (Di + 1−Di)} (DTarget−Di) + Vi (1) The optimum developing bias VTarget is calculated by the equation (1).

Then, the developing bias VTarget is stored in the memory 20 as storage means provided in the image forming apparatus main body, and an image is formed using this value until the next image density control is executed.

Next, the density control of the image forming apparatus according to this embodiment will be described.

First, four different developing biases V1 to V
4, four patches P1 to P4 are formed on the photosensitive drum 1, and densities D1 to D4 for these patches are obtained. Then, the control target density DTarget is selected from among these D1 to D4.
Search for a section that includes. Then, when such a section is found, the developing bias VTarget is calculated by interpolation using the linear interpolation shown in the above-described equation 1. Therefore, in order to perform appropriate density control, the control target density DTarget needs to be included between the patch densities D1 to D4.

In the image forming apparatus of this embodiment, the first time t1 at which the image forming process (developing process) was executed last is clocked by a clock 21 serving as a clocking device, and is passed through a determining circuit 22 serving as a determining device. It is stored in the memory 20 as first time storage means provided in the image forming apparatus main body. When the image forming process is started again, the determination circuit 22 calculates a sleep time s1 = t0−t1 calculated as a difference between the time t1 stored in the memory 20 and the time t0 as the current second time. If this value is equal to or greater than a certain value s1a, the driving means (not shown) sets the developing sleeve 4a and the developer supply roller 4b as charging members in advance for a predetermined time determined based on the sleep time. By starting the image forming process after driving, the image forming process is performed after the charge amount of the toner reduced during sleep is recovered.

For example, the sleep time is s1, the developing device 4
Assuming that the drive time of the developing sleeve 4a and the developer supply roller 4b is Td, the developing device 4
d = 0 (s1 ≦ s1a), Td = αs1 (s1a <s1
<S1max), Td = αs1max (s1max ≦ s
1) The driving is performed according to the following formula. The driving time Td of the developing device 4 is a time Tdmax at which a sufficient amount of toner charge can be obtained even in the case of a new developing device to which no toner is charged, and the sleep time s
The count of 1 stops at s1max = Tdmax / α. Further, a table defining the relationship between the sleep time s1 and the drive time Td of the developing device 4 may be prepared in advance.

By adopting such a configuration, it is possible to prevent the control target density DTarget from moving out of the range of the patch densities D1 to D4 due to a decrease in the charge amount of the toner, and to stably prevent wasteful consumption of the toner. An image having a reduced density can be obtained.

The memory 20 is provided with an area for storing the value of the time t1 at which the last image forming processing was executed. Each time the image forming operation is completed, the time at that time is read from the clock 21 and newly stored. Memory 20 as the value of
Write to. The clock 21 may be provided in either the video controller or the printer engine. Alternatively, the clock 21 may be configured to receive time information from a clock provided in the host computer, and the video controller and the printer engine may have no clock.

As described above, according to this embodiment, the time at which the last image was formed is stored in the memory provided in the main body of the image forming apparatus, and the time is calculated according to the elapsed time calculated from the difference from the current time. The developing sleeve 4a and the developer supply roller 4b
Is driven for a predetermined time, the image forming process is started, so that the charge amount is reduced by being left between the end of the previous image forming process and the reception of the next image forming process command. The developing toner is charged by the developing sleeve 4a and the developer supply roller 4b as needed, and an image having a stable density can be obtained without wasteful consumption of toner.

Embodiment 2 Next, an electrophotographic image forming apparatus according to a second embodiment of the present invention will be described. The description of the same configuration as that of the first embodiment is omitted.

In this embodiment, when the image forming process is started again, the last image forming process (development process) stored in the memory 20 provided in the main body of the electrophotographic image forming apparatus is performed at the time t1 and the current time. If the sleep time s1 = t0−t1 calculated as the difference from the time t0 is equal to or longer than a certain value s1a, the first image density control performed by the image density control circuit 19 immediately after the sleep is canceled, By setting the execution interval for the next second image density control shorter than the normal interval and performing image density control, an appropriate VTarget is obtained following the recovery of the toner charge amount. ing.

Further, after the second image density control, the execution interval of the image density control performed when a predetermined number of images have been formed, not immediately after the release of the sleep mode, remains the same as the normal number. This makes it possible to obtain an image having a stable density while preventing wasteful consumption of toner.

Further, according to this embodiment, the time when the last image was formed is stored in the memory 20 provided in the main body of the image forming apparatus, and the elapsed time calculated from the difference from the current time is stored in the memory 20. Accordingly, since the image density control circuit 19 is configured to shorten the control interval from the start of the image forming process to several times of image density control, the image forming control command is issued after the previous image forming process is completed. Can quickly respond to changes in image forming processing conditions caused by toner whose charge amount has decreased by receiving the toner, and can obtain an image with a stable toner density without wasteful consumption of toner. .

Embodiment 3 Next, an electrophotographic image forming apparatus according to a third embodiment of the present invention will be described. The description of the same configuration as that of the first embodiment is omitted.

In this embodiment, when the image forming process is started again after the sleep, the image forming process (developing process) is stored in the memory 20 provided in the image forming apparatus main body.
Sleep time s1 = t0−t1 calculated as the difference between the time t1 at which is executed and the current time t0 is a certain value s1
a, the normal patch creation and development biases V1 to V4 during the first density control after the image forming process is restarted.
Instead, as shown in FIG. 2, the bias at which the patch is started to be applied in response to the change in the VD characteristic due to sleep is set to V.
1 to V1 'and the same V2 to V4
Changes to 2 ', V3', V4 ', and V1'-V4'
A patch is created using different biases.

Therefore, DTarget is equal to the patch densities D1 'to D1.
An error that deviates from the range of 4 'can be prevented. By changing the bias at the start of the patch,
Since it is possible to cope with a decrease in the toner charge amount without increasing the number of patches and making the interval w between the patches too large, it is possible to suppress an increase in an error in the interpolation calculation according to the above equation 1, and waste toner. , And an image having a stable density can be obtained.

Therefore, according to the present embodiment, the time at which the last image was formed is stored in the memory provided in the main body of the image forming apparatus, and the time is calculated according to the length of the elapsed time calculated from the difference from the current time. The image forming process is changed from the start of the image forming process to the first image density control to form a toner image on the photosensitive drum, so that the next image forming process is completed after the previous image forming process is completed. Quickly respond to changes in image forming processing conditions caused by toner whose charge amount has decreased by being left unattended before receiving a processing command, and obtain an image with a stable toner density without wasteful consumption of toner. Can be done.

Fourth Embodiment Next, an image forming apparatus according to a fourth embodiment of the present invention will be described. In addition, about the structure similar to 1st Example,
The description is omitted.

In this embodiment, when the image forming process is started again after the sleep, the image forming process (developing process) is stored in the memory 20 provided in the image forming apparatus main body.
Sleep time s1 = t0−t1 calculated as the difference between the time t1 at which is executed and the current time t0 is a certain value s1
In the case of “a” or more, during execution of the first density control after resuming the image forming process, as shown in FIG.
Patch P using six developing biases V1 to V6
1 to P6 are created.

Although the intervals w of the developing biases V1 to V6 for forming the patches P1 to P6 are the same, a wider range can be covered because the number of patches is increased, and DTarget is out of the range of the patch densities D1 to D6. Errors can be prevented. Further, since the interval w between the patches is not changed, the error in the interpolation calculation by the above equation 1 does not increase. Furthermore, since the number of patches is increased only in the first image density control immediately after the sleep mode is released, an image having a stable density can be obtained with little increase in toner consumption.

Therefore, according to the present embodiment, the time at which the last image was formed is stored in the memory provided in the main body of the image forming apparatus, and the time is calculated according to the length of the elapsed time calculated from the difference from the current time. From the start of the image forming process to the first image density control, a toner image is formed on the photosensitive drum under a larger number of image forming process conditions than usual. By being left unattended before receiving the next image forming processing command, it quickly responds to changes in image forming processing conditions caused by toner whose charge amount has decreased, and has a stable toner density without wasteful consumption of toner. Images can be obtained.

Fifth Embodiment Next, an image forming apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. The present embodiment has a configuration substantially similar to that of the first embodiment, except that the developing device is configured as a developing cartridge 4A so as to be detachable from the main assembly of the device by a mounting means 30, Is mounted not on the apparatus main body but on the developing cartridge 4A.

In this embodiment, the time when the last image was formed is stored in the memory 20, and when the image forming process is started again after the sleep, the elapsed time calculated from the difference from the current time is calculated. If the value is equal to or more than a certain value, the image forming process is started after the developing sleeve 4a and the developer supply roller 4b are driven for a predetermined time determined based on the sleep time. The amount of charge has been restored.

In the control of the first embodiment, since information on the toner charge amount of each developing cartridge cannot be obtained from the memory provided in the apparatus main body, for example, the user repeats replacement of the developing cartridge and the toner charging amount becomes sufficient. An unnecessary process of applying a charge to the toner by performing a process such as driving the developing sleeve 4a for a predetermined time similarly to the case where a new developing cartridge is mounted, similarly to the case where a new developing cartridge is mounted. Cannot be omitted.

Therefore, in the present embodiment, by adopting a configuration in which a memory is provided on the side of the developing cartridge that is detachable from the main assembly of the apparatus, even if the user repeatedly exchanges the developing cartridge, each developing cartridge lastly becomes the image. It is possible to correctly read the time when the forming process is executed, and to perform the toner charging process only for a necessary and sufficient time.

Therefore, according to the present embodiment, the time when the image was last formed is stored in the memory 2 provided in the developing cartridge 4A.
0, the image forming process is started after the developing sleeve 4a and the developer supply roller 4b are driven for a predetermined time according to the length of the elapsed time calculated from the difference from the current time. Therefore, the developing sleeve 4a and the developer supply roller 4b charge the toner having a reduced charge amount by being left between the end of the previous image forming process and the reception of the next image forming process command. I do. In addition, since the memory for storing the time when the last image was formed is provided not in the main body of the image forming apparatus but in a cartridge that can be removed from the main body, the cartridge can be exchanged correctly and stable without wasteful toner consumption. An image having the adjusted toner density can be obtained.

Embodiment 6 Next, an image forming apparatus according to a sixth embodiment of the present invention will be described. This embodiment has a configuration substantially similar to that of the second embodiment. However, as shown in FIG. In addition, the memory 2 is mounted not on the apparatus main body but on the developing cartridge 4A.

In this embodiment, similar to the second embodiment,
The time when the last image was formed is stored in the memory 20, and when the image forming process is started again after the sleep, if the elapsed time calculated from the difference from the current time is a certain value or more, the sleep is canceled. Immediately after the image density control circuit 19 performs the image density control by setting the execution interval between the first image density control performed by the image density control circuit 19 and the next second image density control to be shorter than the normal interval. , An appropriate VTarget can be obtained following recovery of the charge amount of the toner. Further, the execution interval of the image density control performed when a predetermined number of images have been formed, not immediately after the release of the sleep mode after the second image density control, remains the same as the normal number of images. And an image having a stable density can be obtained.

In this embodiment, as described above, the memory for storing the last time an image was formed is provided not in the image forming apparatus main body but in a cartridge detachable from the main body. As a result, an image having a stable toner density can be obtained without wasting toner.

Embodiment 7 Next, an image forming apparatus according to a seventh embodiment of the present invention will be described. Although the present embodiment has a configuration substantially similar to that of the third embodiment, as shown in FIG. 4, the developing device is a developing cartridge 4A, and is detachably attached to the main assembly of the device by the mounting means 30. In addition, the memory 2 is mounted not on the apparatus main body but on the developing cartridge 4A.

In this embodiment, as in the third embodiment,
The time when the last image was formed is stored in the memory, and when the image forming process is started again after the sleep, if the elapsed time calculated from the difference from the current time is a certain value, after the image forming process is restarted, When the first density control is executed, the bias for starting patch application is changed from V1 to V1 'in accordance with the change in the VD characteristic due to sleep, as shown in FIG. 2, instead of the normal patch development biases V1 to V4. And V2 to V4 make similar changes, and V1 'to
A patch is created using the bias V4 '. Therefore, it is possible to prevent an error that DTarget deviates from the range of patch densities D1 'to D4'. By changing the bias at the start of the patch, it is possible to cope with a decrease in the toner charge amount without increasing the number of patches and without significantly increasing the interval w between the patches. Thus, an image having a stable density can be obtained while preventing wasteful consumption of toner.

In this embodiment, since the memory for storing the time when the last image was formed is provided not in the main body of the image forming apparatus but in a cartridge detachable from the main body of the image forming apparatus, the memory can be properly replaced even when the cartridge is replaced. , And an image having a stable toner density can be obtained.

Embodiment 8 Next, an image forming apparatus according to an eighth embodiment of the present invention will be described. The present embodiment has a configuration substantially similar to that of the fourth embodiment. However, as shown in FIG. In addition, the memory 2 is mounted not on the apparatus main body but on the developing cartridge 4A.

In this embodiment, similar to the fourth embodiment,
The time when the last image was formed is stored in the memory provided in the image forming apparatus main body, and when the image forming process is started again after sleep, when the elapsed time calculated from the difference from the current time is a certain value During the first density control execution after the image forming process is restarted, as shown in FIG. 3, patches P1 to P6 are created using six developing biases V1 to V6, which are two more than the normal four. Although the interval w of the developing bias for forming each patch is the same, since the number of patches is increased, a wider range can be covered, and an error that DTarget deviates from the range of patch densities D1 to D6 can be prevented. Further, since the interval w between the patches is not changed, the error in the interpolation calculation based on Expression 1 does not increase. Furthermore, since the number of patches is increased only in the first image density control immediately after the sleep mode is released, an image having a stable density can be obtained with little increase in toner consumption.

In this embodiment, since the memory for storing the time at which the last image was formed is provided not in the main body of the image forming apparatus but in a cartridge detachable from the main body, it is possible to properly cope with replacement of the cartridge and to waste toner. , And an image having a stable toner density can be obtained.

In the fifth to eighth embodiments,
As a cartridge detachable from the image forming apparatus main body,
Although the case of the developing cartridge including the developing device has been described, the developing device and the electrophotographic photosensitive member are integrally formed, and the process cartridge or the developing device detachably mountable to the apparatus main body, or the electrophotographic photosensitive member. The present invention can also be applied to a process cartridge in which the charging unit and at least one of the cleaning unit are integrally formed, and which is detachable from the apparatus main body.

The communication system between the memory provided in the cartridge and the image forming apparatus main body may be a contact system or a non-contact system.

[0081]

As described above, according to the electrophotographic image forming apparatus and the cartridge of the present invention, the first time storage means for storing the first time and the second time different from the first time are provided. A determination unit configured to determine an image forming operation to be performed based on a time and the first time stored in the first time storage unit, so that the image forming operation is restarted after the image forming operation is stopped In this case, an image having a stable density can be quickly obtained without wasteful consumption of the developer, and therefore, economic efficiency and workability can be improved.
High quality images can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a schematic configuration of an electrophotographic image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a graph illustrating a relationship between a developing bias and an image density for explaining an image density control method according to a third embodiment of the present invention.

FIG. 3 is a graph illustrating a relationship between a developing bias and an image density for explaining an image density control method according to a fourth embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a schematic configuration of an electrophotographic image forming apparatus according to a fifth embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a developing bias and a patch density;
It is a graph which shows D characteristic.

FIG. 6 is a graph illustrating a relationship between a developing bias and an image density for explaining a VD characteristic under each environment and a method of determining a developing bias used for image density control.

FIG. 7 is a graph illustrating a relationship between a developing bias and an image density for explaining a method of determining a developing bias used for image density control in a high temperature and high humidity environment.

FIG. 8 is a graph showing a relationship between a VD characteristic immediately after sleep and a normal VD characteristic.

[Explanation of symbols]

 Reference Signs List 1 photoconductor drum (electrophotographic photoconductor) 2 roller charger (charging means) 4 developing device 4a developing sleeve (charging member) 4b developer supply roller (charging member) 15 pattern generation circuit (image forming means) 17 density sensor ( Density detection means) 19 image density control circuit (image density control means) 20 memory (first time storage means) 21 clock (time measurement means) 22 judgment circuit (judgment means) 30 mounting means

Continued on front page F-term (reference) 2H027 DA10 DA38 DA50 EA04 EA05 EC03 EC06 EC20 ED08 ED09 EE02 EE07 EE08 EF06 2H071 BA05 BA13 BA27 DA06 DA08 DA13 DA15 DA31 2H077 AD02 AD06 AD35 DA04 DA47 DA81 DB08 DB12 DB14 GA03

Claims (15)

[Claims] 1. An electrophotographic image forming apparatus for forming an image on a recording medium, comprising: (a) an electrophotographic photosensitive member;
(B) an electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member, and (c) a developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member. (D) first time storage means for storing a first time; (e) a second time different from the first time; and a first time stored in the first time storage means. And a determination unit for determining an image forming operation to be performed based on the image forming apparatus. 2. An electrophotographic image forming apparatus for detachably mounting a cartridge and forming an image on a recording medium, comprising: (a) an electrophotographic photosensitive member; and an electrostatic latent member formed on the electrophotographic photosensitive member. Mounting means for removably mounting a cartridge having a developing device for developing an image; (b) first time storage means for storing a first time; and (c) said first time An image forming operation to be executed based on a second time different from the first time and the first time stored in the first time storage means. Forming equipment. 3. The electrophotographic image forming apparatus according to claim 1, wherein the first time is a time when an image is formed last, and the second time is a current time. 4. The developing device includes a charging member for charging a developer, and the determining unit controls the charging member based on the first time and the second time before starting the developing process. 4. An electrophotographic image forming apparatus according to claim 1, wherein the operation time is determined. 5. The electrophotographic image forming apparatus executes image density control at a predetermined interval, and the determining means sets an execution interval of the image density control based on the first time and the second time. 4. The electrophotographic image forming apparatus according to claim 1, wherein the value is changed to a value different from the predetermined interval. 6. An image forming means for forming a reference pattern image on the electrophotographic photosensitive member under a plurality of different process conditions, a density detecting means for detecting the density of the reference pattern image, and a density detection result. Image density control means for determining a process condition for executing predetermined image density control based on the reference pattern image based on the first time and the second time. 4. An electrophotographic image forming apparatus according to claim 1, wherein a process condition for forming the image is changed. 7. An image forming means for forming a reference pattern image on the electrophotographic photoreceptor under a plurality of different process conditions; a density detecting means for detecting the density of the reference pattern image; Image density control means for determining process conditions for performing predetermined image density control based on the first time and the second time.
4. The electrophotographic image forming apparatus according to claim 1, wherein the number of the reference pattern images is changed based on the time. 8. The cartridge according to claim 2, wherein said cartridge further comprises at least one of a charging unit for charging said electrophotographic photosensitive member and a cleaning unit for cleaning said electrophotographic photosensitive member. 8. The electrophotographic image forming apparatus according to any one of claims 1 to 7. 9. A cartridge detachable from a main body of an electrophotographic image forming apparatus, comprising: (a) an electrophotographic photosensitive member;
(B) a developing device for developing an electrostatic latent image formed on the electrophotographic photosensitive member, and (c) first time storage means for storing a first time, wherein the electrophotographic image is formed. A cartridge, wherein a determination unit provided in the main body of the forming apparatus determines an image forming operation to be executed based on the first time and the second time. 10. The cartridge according to claim 9, wherein the first time is a time when the process cartridge last forms an image, and the second time is a current time. 11. The developing device includes a charging member for charging a developer, and the determining unit controls the charging member based on the first time and the second time before starting a developing process. 11. The cartridge according to claim 9, wherein the drive time is determined in advance. 12. The electrophotographic image forming apparatus main body executes image density control at a predetermined interval, and the determining means determines an execution interval of the image density control based on the first time and the second time. 11. The cartridge according to claim 9, wherein the value is changed to a value different from the predetermined interval. 13. An electrophotographic image forming apparatus main body, comprising: an image forming means for forming a reference pattern image on the electrophotographic photoreceptor under a plurality of different process conditions; and a density detector for detecting a density of the reference pattern image. Means, and image density control means for determining a process condition for performing predetermined image density control based on the density detection result, wherein the determination means determines the first time and the second time at the first time and the second time. 11. The cartridge according to claim 9, wherein a process condition for forming the reference pattern image is changed based on the condition. 14. An electrophotographic image forming apparatus main body, comprising: an image forming means for forming a reference pattern image on the electrophotographic photosensitive member under a plurality of different process conditions; and a density detector for detecting a density of the reference pattern image. Means, and image density control means for determining a process condition for performing predetermined image density control based on the density detection result, wherein the determination means determines the first time and the second time at the first time and the second time. 10. The number of the reference pattern images is changed based on the number of the reference pattern images.
Or 10 cartridges. 15. The apparatus according to claim 9, further comprising at least one of a charging unit for charging the electrophotographic photosensitive member and a cleaning unit for cleaning the electrophotographic photosensitive member. That cartridge.