JPH11258893A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device capable of shortening a waiting time until an image forming operation is started in the case the developing ability of developer is drastically reduced by changing a period for executing an aging operation according to the variation of the developing ability of the developer. SOLUTION: Based on the image density detection result of a reference pattern by a density sensor, an aging time necessary for stabilizing the electrostatically charged quality of the developer in the case of assuming that the aging operation is executed with the previously set toner consumption and toner replenishment per unit time is calculated (step S4). In the case a time required to reach a copying allowable state is shorter than the aging time (N at step 86), the aging operation is executed only as long as the time required to reach the copying allowable state.

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 facsimile, and a printer.
An image carrier, a developing device for developing the latent image formed on the image carrier with a two-component developer containing toner and carrier, and forming a reference latent image for detection on the image carrier; A reference toner image forming means for developing a reference latent image by the developing device to form a reference toner image; an image density detecting means for detecting an image density of the reference toner image; And a toner replenishing means for replenishing replenishing toner into the developing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus using a two-component developer containing a toner and a carrier, a reference toner image is formed on an image carrier, and the image density of the reference toner image is measured by a reflection type photo sensor or the like. There is known an image density detecting device which controls the toner density by detecting the image density and supplying toner to a developing device based on the detection result.

Recently, it has been desired to shorten and simplify the “installation time” from the delivery and installation of a machine to the state where an image can be formed and handed over to a user. Until now, the machine was installed by a dedicated service person.However, due to the demand for cost reduction of specialized education and the reduction of personnel, a service person who handles many models who do not know the operation and adjustment method of the machine in detail. And salesmen only. For this reason, it is required that the machine be unpacked, turned on, and ready for copying.

Further, in an image forming apparatus using a two-component developer, when the developer is set in the developing device, it is necessary to take out the developing device, set the developer, and to some extent remove parts. Further, in a color image forming apparatus, these operations need to be performed for four colors, so that more time is required. For this reason, some machines perform factory shipment with a developer set in a developing device.

[0005] However, the number of days from factory shipment to the user's hand may be as short as several weeks, and as long as several months or more. During this time, it is often stored in a warehouse without air conditioning or in a place where there is no difference from outside air. Overseas, they may be transported in warehouses at the bottom of the ship at plus several tens of degrees Celsius or in warehouses of aircraft at minus tens of degrees Celsius, which is even more severe.

[0006] When the developer is shipped from the manufacturing factory, it is in a sealed package so as not to be affected by humidity. However, when the developer in which the package is opened is set in the developing device and the device is exposed to a harsh environment for a long time due to seasons or transportation means, the developer in the developing device of the device becomes a two-component developer in particular. In the case of, due to condensation (moisture absorption) due to long-term storage or sudden environmental changes,
The charge amount of the toner tends to decrease.

In an image forming apparatus employing the above-described toner replenishment method, when a developer having a reduced charge amount is used, the developing ability of the developer is increased due to a small charge amount at the time of delivery to a machine. The image density of the toner image increases. Then, in order to adjust this, toner supply is controlled so that the toner concentration in the developer becomes low. As a result, the toner density of the developer decreases, and an abnormal image such as insufficient image density, uneven filling of a solid portion, or a brush mark (head trace) tends to occur. Further, when the image forming operation is started, the toner and the carrier are frictionally charged by a regulating member such as a doctor, or the toner newly replenished to the developing device adheres to the carrier that has been consumed and removed. The charge amount increases due to frictional charging, and attempts to return to the charge amount before the decrease. Since the maximum value of the charge amount of the developer is determined by the charging ability of the toner and the carrier, the larger the amount of decrease due to standing, the larger the increase amount of the charge amount. For this reason, as the amount of decrease in the amount of charge due to standing is greater, the rate of increase in the amount of charge is greater. As a result, the developing ability of the developer decreases, and the image density of the reference toner image on the photoconductor decreases. For this reason, a large amount of toner is supplied this time so that the toner concentration of the developer becomes high. However, as a result, there arises a problem that the toner supply cannot keep up or that toner scattering due to a large amount of toner supply increases. In addition, it is difficult to perform accurate density control in a state where the charge amount is largely changed. In particular, in the case of a color, it is necessary to pay attention because a desired color cannot be reproduced unless the density control is performed correctly.

Therefore, as an apparatus capable of solving such a problem, the image density of a reference toner image formed on a photoreceptor is detected before image formation is started, and based on the detection result, the reference toner image of the reference toner image is detected. By performing the aging operation of the developer which repeats the consumption of the toner in the developer and the replenishment of the toner until the image density reaches a predetermined density,
One that stabilizes the charge amount of a developer is known.

[0009]

However, in the above-mentioned apparatus, it may take several tens of minutes until the charge amount of the developer is stabilized depending on the deterioration state of the developer and the environment at the time of installation. There was a problem that it became long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to change a period for performing an aging operation in accordance with a change amount of a charge amount of a developer and to change a charge amount of the developer. It is an object of the present invention to provide an image forming apparatus capable of shortening a waiting time until image formation is started in a case where is greatly reduced.

By changing the detection interval for detecting the image density of the reference toner image according to the stability of the image density of the reference toner image, the toner density can be accurately adjusted without unnecessarily increasing the toner consumption. There is also known a toner density adjusting method capable of adjusting (Japanese Patent Laid-Open No. 6-258951).
No.). However, in this apparatus, when the charge amount of the developer is very low, the toner density of the developer becomes low, and abnormal images such as insufficient image density, uneven filling of solid portions, and brush marks (head marks) occur. The aforementioned problem,
The above-described problem that the toner supply cannot keep up or the toner scattering due to a large amount of toner supply cannot be solved because the rate of increase when the charge amount is increased due to the replacement of the toner after the start of image formation is large.

[0012]

In order to achieve the above object, the present invention is directed to a two-component developing method including an image carrier and a latent image formed on the image carrier, comprising a toner and a carrier. A developing device for developing with a developer, a reference toner image forming means for forming a reference latent image for detection on an image carrier, and developing the reference latent image by the developing device to form a reference toner image; Image density detecting means for detecting the image density of the toner image; toner replenishing means for replenishing toner for replenishment in the developing device based on the detection result by the image density detecting means; Aging operation control means for executing an aging operation for repeating supply of toner to the developing device; and forming a reference toner image by the reference toner image forming means during a warm-up operation before the image forming operation by the image forming apparatus. And a stabilization control unit for performing an aging operation by the aging operation control unit based on a result of detecting the image density of the reference toner image by the image density detection unit, thereby stabilizing a charge amount of the developer. In the image forming apparatus having the image forming apparatus, it is assumed that the aging operation is performed by the aging operation control unit with the toner consumption amount and the toner replenishment amount per unit time set in advance based on the detection result by the image density detection unit. Calculating a period required for stabilizing the developer charge amount, and when the calculated period is equal to or longer than a preset set period, performing the aging operation only during the set period. Is constituted.

In this image forming apparatus, the aging operation control means is controlled by the stabilization control means based on a detection result by the image density detection means, using a preset toner consumption amount and toner replenishment amount per unit time. Calculates the period required for stabilizing the developer charge amount when it is assumed that the aging operation is performed, and if the calculated period is longer than a preset set period, the aging is performed only for the set period. Execute the operation. Thus, the period during which the aging operation is performed does not become longer than the previously set period.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, when the calculated period is equal to or longer than a preset set period, the aging operation is performed only during the set period and the remaining period is set. Is characterized in that the stabilization control means is configured to be executed after the image forming operation started after the image forming operation is enabled or after the next warm-up operation. is there.

In this image forming apparatus, when the calculated period is equal to or longer than a preset set period, the stabilization control means causes the aging operation to be executed only during the set period. Is executed after the image forming operation started after the above-mentioned image forming operation is enabled or when the next warm-up operation is performed. Thus, the image forming operation can be performed with the charge amount of the developer being more stable.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, when the calculated period is equal to or longer than a preset set period, the aging operation is performed only for the set period, and then the aging operation is performed again. The stabilization control means is configured to form a reference toner image by the reference toner image forming means, and to detect the image density of the reference toner image by the image density detecting means, and to perform detection by the image density detecting means. A condition changing unit that appropriately changes an image forming condition at the time of the image forming operation started after the image forming operation becomes possible based on the result from the image forming condition at the time of the normal image forming; Is what you do.

In this image forming apparatus, if the calculated period is equal to or longer than a preset set period, the aging operation is performed only during the set period, and then the reference toner image forming means again uses the reference toner image forming means. An image is formed, and the image density of the reference toner image is detected by the image density detecting means. Then, based on the detection result, the condition changing means appropriately changes the image forming condition at the time of the image forming operation started after the image forming operation is enabled from the normal image forming condition. Specifically, if the detected image density at this time is within the desired image density range, it is considered that the charge amount of the developer has been stabilized, and after the image forming operation becomes possible. Is performed under the image forming conditions for normal image formation. When the detected image density is out of the range of the desired image density, it is considered that the charge amount of the developer is not stabilized, and the image started after the image forming operation is enabled. The image forming conditions at the time of forming are changed from the image forming conditions at the time of normal image forming. More specifically, if the detected image density is lower than the desired image density, it is considered that the developing ability of the developer has decreased, and the image forming conditions are changed so that the developing ability increases. . When the detected image density is higher than the desired image density, it is considered that the developing capability of the developer is high, and the image forming conditions are changed so that the developing capability is low.

According to a fourth aspect of the present invention, there is provided an image carrier, a developing device for developing a latent image formed on the image carrier with a two-component developer containing a toner and a carrier, and detecting the latent image on the image carrier. A reference toner image forming means for forming a reference latent image for use, developing the reference latent image with the developing device to form a reference toner image, an image density detecting means for detecting an image density of the reference toner image, Based on the detection result by the image density detecting means, a toner replenishing means for replenishing toner for replenishment in the developing device and an aging operation for repeating consumption of toner of the developing device and replenishment of toner to the developing device are executed. Aging operation control means for causing the reference toner image forming means to form a reference toner image during a warm-up operation before the image forming operation by the image forming apparatus; An aging operation control unit for performing an aging operation based on a result of detecting an image density of an image, and a stabilization control unit for stabilizing a charge amount of a developer; The stabilization control means so as to set the toner consumption per unit time at the time of executing the aging operation based on the detection result by the image density detection means so that the charge amount of the developer is stabilized. It is characterized by having comprised.

In this image forming apparatus, the aging based on the detection result by the image density detecting means is performed by the stabilizing control means so that the charge amount of the developer is stabilized during the warm-up operation. The toner consumption per unit time at the time of executing the operation is set. This setting may be performed by the following method, for example. That is, the amount of toner consumption per unit time at the time of executing the aging operation (hereinafter, referred to as necessary toner consumption) required for stabilizing the charge amount of the developer during the warming-up operation is determined. The toner consumption per unit time at the time of executing the operation may be set to the required toner consumption. Alternatively, the necessary toner consumption is obtained after the toner consumption per unit time at the time of executing the aging operation is set to a predetermined value in advance. If the required toner consumption is equal to or less than the predetermined value, the toner consumption per unit time when the aging operation is performed is set to the predetermined value, and the required toner consumption is set to the predetermined value. If the value is larger than the value, the toner consumption per unit time at the time of executing the aging operation may be set to the required toner consumption. With such a setting, the time required for performing the aging operation does not become longer than the time required for the warm-up operation, for example, the time required for starting up the fixing device.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described below. In this copying machine, a drum-shaped photoconductor 1 as an image carrier that is driven to rotate in the direction of arrow A in the figure is disposed at the center of the apparatus main body. Around the photoreceptor 1, a charger 2, a developing unit 7, a density sensor 12 as image density detecting means for detecting an image density of a toner image formed on the photoreceptor, a transfer device 9, A cleaning device 11 and the like are provided.

The developing device 7 includes a developing roller 4 and a stirring roller 5, and includes a developer accommodating section for accommodating a two-component developer containing a toner and a carrier, and replenishes toner to the developer accommodating section. And a toner replenishing device 6 to be used. The developer in the developer accommodating section is supplied to the developing roller 4 while being stirred by the stirring roller 5, and is used for a developing operation. At the time of factory shipment, the developer is set in the developer accommodating section. On the other hand, the toner is easily spilled during transport and stains the inside of the apparatus, and the cartridge is usually of a cartridge type and does not take much time to set. Therefore, the toner is not set in the toner supply device 6. The density sensor 12
Outputs an output corresponding to the reflection density of the toner image on the photoreceptor 1, and calculates the image density (toner adhesion amount) of the toner image formed on the photoreceptor by a CPU (not shown).

In the above-described copying machine, after the surface of the photosensitive member 1 is uniformly charged by the charger 2, exposure from a writing optical system unit (not shown) is performed based on an image signal from an image processing unit (not shown). 3, a latent image corresponding to the image of the document is formed. In the developing device 7, the toner is charged to a polarity such that the toner adheres to the electrostatic latent image by frictional charging with the carrier by stirring the developer. The charged developer is pumped up by the developing roller 4 and comes into contact with the surface of the photoconductor 1. At the time of this contact, the electrostatic latent image on the photoconductor 1 is developed. (Hereinafter, margin)

On the other hand, the transfer paper 8 loaded and stored in a paper feed cassette (not shown) is conveyed in the direction of arrow B toward a transfer area facing the photosensitive member at a timing by a paper feeder (not shown) and a registration roller (not shown). Is done. The transfer device 9 transfers the toner image on the photoconductor 1 to the transfer paper 8 that has entered the transfer area. Then, the transfer paper 8 on which the toner image has been transferred is conveyed to the fixing device 10 and the fixing device 10
When passing through, the toner image is fixed. The fixing device 10 includes:
A fixing roller 13 having a heater therein, a pressure roller 14, and a temperature sensor 15 for measuring the temperature of the surface of the fixing roller. The surface temperature of the fixing roller is controlled to a constant value from the output of the temperature sensor 15. Have been.

The untransferred toner remaining on the photoreceptor 1 after the transfer of the toner image is cleaned from the photoreceptor 1 by a cleaning device 11.
Collected in 1. Then, the photoconductor 1 after cleaning
The surface is neutralized by a static elimination lamp (not shown) to prepare for the next imaging process.

FIG. 2 is a block diagram of a control system of the copying machine. This control system includes a main control unit 2 as control means.
01 and a plurality of peripheral control units. The main control unit 201 includes a CPU 202, a ROM 203 storing a control program and various data, a RAM 204 temporarily storing various data as a work area, and an I / O interface for performing input / output with each peripheral control unit. And a unit 205.

The main control unit 201 is provided with an I / O
The laser optical system control unit 206, the density sensor 12, the toner supply circuit 20 via the interface unit 205
7, charging roller power supply 208, developing bias power supply 209,
The fixing temperature sensor 15, the fixing heater 210, and the like are connected. The laser optical system control unit 206 includes a main CPU 2
A laser optical unit (not shown) is controlled based on a command from the controller 02. The charging roller power supply 208 is connected to the main CPU 2
The high voltage is applied to the charger 2 based on the instruction from the charger 02. The developing bias power supply 209 applies a developing bias voltage to the developing roller 4 based on a command from the main CPU 202. The density sensor 12 optically detects the reflection density of the toner image on the photoconductor 1. As the density sensor 12, for example, a sensor composed of a light emitting diode and a phototransistor can be used. Toner supply circuit 207
Controls a toner supply motor (not shown) of the toner supply device 6 based on a command from the main CPU 202 to supply toner of each color to each developing device. The CPU 202 compares the signal from the fixing temperature sensor 15 with the data stored in the ROM 203 and determines whether the power of the fixing heater 212 is
N / OFF is performed, and the temperature of the fixing heater is controlled.

In this copying machine, an electrostatic latent image of a reference pattern for detection is formed on the photoreceptor 1 at a predetermined timing, and the pattern is developed by the developing unit 7, and the developed reference pattern is developed. The image density of the pattern is
To detect. The CPU 202 controls the toner supply motor (not shown) of the toner supply device 6 by the toner supply circuit 207 based on the detection result, and the toner supply from the toner supply device 6 is performed. As a result, control is performed so that the toner density of the developer in the developing device 7 becomes a predetermined density.

FIG. 3 is an explanatory diagram showing a change in the amount of charge of the developer depending on the standing time. As described above, when the developer is shipped from the manufacturing factory, the developer is in a sealed package. The change in the charge amount of the developer in the unopened state of the package is indicated by a characteristic line a1. Further, a change in the charge amount of the developer when the apparatus is left in a state where the package is opened and set in the developing device is indicated by a characteristic line a2. In addition, the characteristics of the charge amount of the developer when the apparatus is left under a condition where the storage condition and the transport condition are worse are shown by a characteristic line a.
Indicated by 3. From this figure, it is understood that the charge amount of the developer in the apparatus gradually decreases before the copying machine in which the developer is set in the apparatus reaches the user. Further, it can be seen that the speed of the decrease increases as the storage conditions and the transport conditions deteriorate. In addition, it can be seen that, even in the unopened developer, the charge amount is reduced although the level is small. Due to such a decrease in the charge amount, the developing ability of the developer changes, and thus the above-mentioned problem, that is, the problem that an abnormal image is easily generated or the control of the image density becomes difficult. Occurs.

In the copying machine according to the present embodiment, an electrostatic latent image of a reference pattern for detection is formed on the photoreceptor 1 during a warm-up operation before image formation, and the developing device 7
The pattern is developed, and the image density of the developed reference pattern is detected by the density sensor 12. And
Based on this detection result, the aging operation is executed by the aging operation control means for executing the aging operation for repeating the consumption and replenishment of the toner in the developing device 7, and the stabilization control means for stabilizing the charge amount of the developer is provided. Have. In the illustrated device, the main control unit 20
1 has a function as the aging operation control means and the stabilization control means. By starting the image forming operation in a state where the charge amount of the developer is stabilized, the occurrence of the abnormal image can be prevented, and the image density can be controlled well and the image forming operation can be performed satisfactorily. Is available.

In the developing device according to the present embodiment, the execution of the aging operation is controlled so as to reduce the time required to start the image forming operation. FIG.
5 is a flowchart showing an example of control of the execution of the aging operation (hereinafter referred to as aging execution control) by the main control unit 201. In the aging execution control flow of FIG. 4, the main control unit 201 first inputs an input signal from the fixing temperature sensor 15 that detects the fixing temperature of the fixing device 10 in order to distinguish the power-on state from the abnormality processing such as a jam. Then, it is determined whether or not the fixing temperature is equal to or lower than a preset temperature Th (step S1). Here, when the fixing temperature exceeds Th (N in step S1), it is considered that since the fixing temperature is high, the time from when the apparatus is turned off to when it is turned on is short, that is, the leaving time is short. So that
It is determined that aging is unnecessary or that the power has been turned off / on due to a machine trouble or the like, and the aging operation is not executed. On the other hand, when the fixing temperature is equal to or lower than Th,
A latent image of a reference pattern of, for example, 20 [mm] × 20 [mm] is formed on the photoreceptor 1 under image forming conditions of a predetermined reference pattern, and the latent image is developed by the developing device 7. Then, a reference toner image is formed (Step S2).

Next, the image density of the reference toner image is detected by the density sensor 12 (step S3). And
The CPU 202 of the main control unit 201 performs a developer operation on the assumption that the aging operation is performed at a preset toner consumption amount and toner supply amount per unit time based on the detection result from the density sensor 12. The time required for stabilizing the charge amount (hereinafter referred to as aging time) is calculated (step S4). During the aging operation, the toner is consumed while the toner concentration of the developer in the developing device 7 is kept constant. Therefore, the toner consumption amount is substantially equal to the toner supply amount. The toner replenishment during the aging operation may be performed by replenishing a predetermined amount of toner corresponding to the amount of toner consumed by the toner consumption. The aging time is calculated by, for example, the difference ΔMp between the image density of the reference toner image shown in FIG. 5 and a preset target value of the image density, and the aging time required until the charge amount of the developer becomes saturated. Can be determined in advance and calculated from this relationship.

Next, the fixing temperature of the fixing device 10 is detected again by the fixing temperature sensor 15 (step S).
5). Then, based on the detection result, the time required until the apparatus can perform the copy operation is calculated. The calculation of this time is performed, for example, by changing the temperature of the fixing roller after the fixing heater shown in FIG.
A temperature change until the temperature reaches the reload temperature is obtained in advance, and the time until the temperature reaches the reload temperature can be calculated as the time required until the copying operation becomes possible. Note that the warming-up time in the figure is the time required from reading the fixing temperature data T0 of the fixing temperature sensor 15 immediately after the power is turned on until the copying operation becomes possible.

The reason why the fixing temperature is detected again in step S5 is as follows. That is, since the fixing heater is turned on and the fixing temperature is rising even during the creation of the reference toner image, the time required until the copying operation becomes possible is calculated based on the temperature detected before the creation of the reference toner image. The fixing temperature is also high. For this reason, if the time required until the copying operation becomes possible is calculated based on the temperature detected before the creation of the reference toner image, the time cannot be accurately calculated.

Next, the aging time obtained as described above is compared with the time required until the copy operation is enabled, and whether the aging time is within the time required until the copy operation is enabled is determined. Is determined (step S6). If the aging time is shorter than the time required until the copying operation becomes possible (Y in step S6), the aging operation is performed during the aging time (step S7). Thereafter, a copy operation becomes possible. On the other hand, if the time until the copy operation becomes available at step S6 is shorter (N at step S6), aging is performed for the time until the copy operation becomes available (step S8), and the remaining aging is performed. The time is stored, and a flag indicating that the aging time remains, that is, aging is not completed (hereinafter, referred to as an aging remaining flag) is turned on (step S).
9).

The above aging operation may be performed as follows. That is, a predetermined toner consumption pattern is developed under appropriate image forming conditions. For example, it may be formed under the same image forming conditions as the image forming conditions of the reference toner image. For the above-mentioned toner consumption pattern, the pattern area and the written value may be determined so that a necessary amount of toner consumption is obtained.

The aging operation for the remaining aging time (hereinafter referred to as a remaining aging operation) is executed after the copy is completed. FIG. 7 shows an example of the remaining aging operation execution control after the completion of the copying operation. First, it is determined whether or not the aging remaining flag is ON (step S).
10) If the flag is not turned on (step S
In N) at 10, the control is terminated as it is.

On the other hand, if the aging residual flag is ON in step S10 (step S10).
In Y), it is determined whether or not the copy operation has been completed (step S11). If the copy operation has not been completed (N in step S11), the process proceeds to step S11 again, and it is repeatedly determined whether the copy operation has been completed. When it is determined that the copy operation has been completed (Y in step S11), the remaining aging time is executed (step S12).

As described above, according to the aging operation execution control of FIG. 4, even when a long time aging is required, the aging is not performed longer than the time required for warming up the apparatus, and the waiting time until the start of the copying operation is obtained. Time can be reduced. Therefore, operability is improved.
Further, even if the long-term aging is not performed, the aging operation for the remaining aging time is performed after the copy is completed, so that the charge amount of the developer finally reaches a stable level. Can be reached. Therefore, it is possible to prevent a change in the developing ability of the developer due to a decrease in the charge amount of the developer, specifically, to prevent the occurrence of an abnormal image due to a decrease in the toner density in the developer, and to suppress an increase in the image density. Therefore, a good image can be obtained.

Here, if the remaining aging time is longer than the time required for the warm-up, the waiting time until the next copy operation becomes possible becomes longer. Therefore, when the remaining aging operation is performed in step S12, the remaining aging time is compared with the time (hereinafter, referred to as a warming-up aging time) T1 during which the aging operation is performed during the warm-up, and the remaining aging time is compared. Is longer than the warming-up aging time, the aging operation is performed only for the warming-up aging time, and the remaining aging time is stored and the remaining aging time remains as in step S9 of the control in FIG. It is desirable to turn on a flag indicating that there is, that is, aging is not completed (hereinafter, referred to as an aging remaining flag). And
When the remaining aging operation execution control is performed again, the remaining aging operation may be executed.

FIG. 8 shows a change in the charge amount of the developer with time when the conventional aging operation execution control is performed in a device in which the charge amount of the developer is greatly attenuated due to being left for a long period of time, and the warming-up aging time. FIG. 9 is a diagram illustrating a change over time of a charge amount of a developer when an aging operation execution control for repeatedly executing an aging operation for every T1 minutes is performed. In the figure, a characteristic line b1 indicates a change over time of the charge amount of the developer when the conventional aging operation execution control is performed, and a characteristic line b2 indicates the aging operation execution control for repeatedly performing the aging operation by the warming-up aging time T1. In this case, the change in the amount of charge of the developer over time is shown, and the characteristic line b3 shows the decrease in the amount of charge of the developer due to leaving. When the conventional aging operation execution control is performed, when it is calculated that the aging time required for the developer to stabilize is T2, the aging operation for the calculated aging time T2 is continuously performed during the warm-up. Execute Therefore, the copy operation cannot be started during the calculated aging time T2, and the waiting time becomes very long. On the other hand, when the aging operation is repeatedly performed every warming-up aging time T1 minutes, the waiting time until the copying operation is started is set to the warming-up aging time T1.
It will not be longer. Therefore, operability is improved. In addition, since the aging operation is performed little by little, and finally the charge amount of the developer can reach a stable level, the image quality can be kept good.

The timing for executing the remaining aging operation execution control may be appropriately set according to the frequency of copying. For example, it is executed after a predetermined number of copies are completed in accordance with the number of copies of the machine to be used. The predetermined number may be set by a service person.

FIG. 9 is a flowchart showing another example of the aging operation execution control. In this example,
Steps S1 to S6 and step S7 executed in the case of Y in step S6 are the same as the processing of FIG. 4 described above, and thus description thereof will be omitted. In this example, the process executed when it is determined that the time until the calculated copy operation becomes possible is shorter than the aging time calculated in step S6 (N in step S6). Is different from the processing of FIG. 4 described above. Specifically, in the case of N in step S6, first, aging is performed for the time until the copy operation becomes possible (step S6).
21), a reference toner image is created again (step S2)
2). Then, the image density of the reference toner image is detected by the density sensor 12 (step S23), and the detected image density value is compared with a preset target value of the image density. The image forming conditions after the start of the copy operation are changed based on the result (step S24). For example, the development potential as an image forming condition may be changed. Hereinafter, an example in which the development potential is changed will be described. FIG. 10 is a graph showing the relationship between the development potential and the amount of toner attached per unit area (hereinafter, simply referred to as “toner attached amount”). The relationship between the toner adhesion amount and the developing potential can be approximated by a straight line as shown in FIG. 10, and the slope of this straight line indicates the developing ability. Ppot is a development potential when a reference toner image is created, and the target value of the toner adhesion amount at that time is Mp. Ma is a target value of the maximum amount of applied toner after the image forming operation of the image forming apparatus is started. The developing characteristic at this time is a characteristic line c1. That is, if the development is performed with the development potential of Vpot, the amount of adhered Ma can be obtained. here,
When the value of the image density of the reference toner image detected again in step S23 of FIG. 9 is Mp ′ (> Mp) shown in FIG. 10, the developing characteristic at this time is more developed than the characteristic line c1. It is considered that the characteristic line c2 has high performance. Therefore, when an image is formed with the development potential of Vpot after the start of the image forming operation, the toner adhesion amount is Ma ′.
And the image density becomes much higher than the target density. Therefore, when the developing ability is higher than the target developing ability and the image density tends to increase, the developing potential is changed so as to decrease the image density. Specifically, when an image having the toner maximum adhesion amount Ma is to be obtained when the development characteristic is a straight line c2, the development potential Vpot '= Mp / M
The image may be formed at p ′ × Vpot. To change the developing potential, for example, the output of the charger and the output of the developing bias may be changed. If necessary, the light quantity at the time of exposure may be changed.

As described above, according to the aging operation execution control of FIG. 9, even when aging is required for a long time, aging is not performed longer than the time required for warming up the apparatus, and the waiting time until the start of the copying operation is obtained. Time can be reduced. Therefore, operability is improved.
Further, even if the long-term aging is not performed, the image forming conditions are changed to the optimum values to change the developing ability of the developer, specifically, the abnormal image due to the decrease in the toner concentration in the developer. Generation can be prevented, and an increase in image density can be suppressed. Therefore, a good image can be obtained.

FIG. 11 is a flowchart showing still another example of the aging operation execution control. In this example, the main control unit 201 first determines the state when the power is on from the time when the fixing device 10
It is determined whether or not the fixing temperature is equal to or lower than a preset temperature Th based on an input signal from the fixing temperature sensor 15 that detects the fixing temperature (step S3).
1). Here, if the fixing temperature exceeds Th (N in step S31), aging cannot be performed because the fixing temperature is high and the time until warm-up is short, or the power is turned off / on due to mechanical trouble or the like. And the aging operation is not performed. On the other hand, if the fixing temperature is equal to or lower than Th, for example, 20 [mm] × 2 on the photoconductor 1 under the image forming condition of the predetermined reference pattern.
A latent image having a reference pattern of 0 [mm] is formed, and
Then, the reference toner image is formed by developing the latent image (step S32).

Next, the image density of the reference toner image is detected by the density sensor 12 (step S33).

Next, the fixing temperature of the fixing device 10 is detected again by the fixing temperature sensor 15 (step S3).
4). Then, based on the detection result, the time required until the apparatus can perform the copy operation is calculated. The calculation of this time is performed, for example, by changing the temperature of the fixing roller after the fixing heater shown in FIG.
A temperature transition until the temperature reaches the reload temperature is obtained in advance, and the temperature can be calculated from the temperature transition.

The time required to enable the copy operation obtained as described above is defined as the time during which the aging operation can be performed (hereinafter referred to as aging possible time).
Based on the image density detection result of the reference toner image detected in step (a), the amount of toner consumed per unit time necessary to stabilize the charge amount of the developer within the aging possible time is calculated (step S36). The calculation of the toner consumption can be performed as follows. FIG. 12 is an explanatory diagram showing the relationship between the amount of toner consumption and the amount of charge of the developer. In a two-component developer, the toner is charged by frictional charging between the toner and the carrier, but if left for a long period of time, the frictional charging of each other will decrease as described above. Therefore, it is generally known that the toner is removed from the carrier by toner consumption (development), and the amount of charge is increased by frictional charging with new toner. Therefore,
As the toner consumption increases, the charge amount also increases greatly. Further, from the difference ΔMp between the image density of the reference toner image detected in step S33 and a preset target value of the image density, it is possible to determine how much the charge amount of the developer is less than the desired charge amount. Desired. Therefore,
From these information, the difference ΔMp between the detected image density value of the reference toner image and the preset target value of the image density as shown in FIG. 13 and the charge amount of the developer are in a stable state. The relationship with the toner consumption during the aging operation required to reach the charge amount can be obtained. Therefore, by previously obtaining this relationship, the toner consumption can be calculated from the difference ΔMp between the image density detection value of the reference toner image and a preset target value of the image density.

Then, an aging operation is performed so that the toner is consumed at the toner consumption amount per unit time calculated in step S36 (step S37). Specifically, the area of the pattern for toner consumption may be increased as compared with the case of normal aging, or the development amount (writing value) of the pattern may be increased. Of course, these may be combined.

As described above, according to the aging operation execution control of FIG. 11, even when aging for a long time is required,
Aging is not performed more than the time required for warming up the apparatus, and the waiting time until the start of the copying operation can be reduced. Therefore, operability is improved. Further, by changing the toner consumption per unit time during the aging operation, the charge amount of the developer can be stabilized in the same manner as in the case of performing the long-term aging. Changes in performance Specifically, it is possible to prevent the occurrence of an abnormal image due to a decrease in the toner density in the developer, and to suppress an increase in the image density. Therefore, a good image can be obtained.

In the aging operation execution control shown in FIG. 11, each time the control is executed, a unit time per unit time during the aging operation necessary for stabilizing the charge amount of the developer during the warming-up operation is required. (Hereinafter referred to as required toner consumption), and the toner consumption per unit time at the time of executing the aging operation is set to the required toner consumption. After setting the toner consumption per unit time to a predetermined value in advance,
The required toner consumption is determined, and the required toner consumption is
If the value is equal to or less than the predetermined value, the toner consumption per unit time at the time of performing the aging operation is set to the predetermined value, and only when the necessary toner consumption is larger than the predetermined value, The toner consumption per unit time at the time of executing the aging operation may be set to the required toner consumption.

As described above, in order to perform the aging operation in a state where the toner concentration is constant, the toner consumption amount per unit time and the toner replenishment amount are equal to the toner consumption amount when the aging operation is performed. It is desirable to set the amount.

[0052]

According to the first to third aspects of the present invention, the operability is improved because the waiting time until the start of image formation when the charge amount of the developer is significantly reduced can be reduced. Has an excellent effect.

In particular, according to the invention of claim 2, there is an excellent effect that an image can be formed more favorably.

Further, according to the invention of claim 3, there is an excellent effect that an image can be formed more favorably.

According to the fourth aspect of the present invention, the waiting time until image formation is started when the charge amount of the developer is significantly reduced can be shortened, so that the operability is improved. effective. There is also an excellent effect that image formation can be performed more favorably.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an electrophotographic copying machine according to an embodiment.

FIG. 2 is a block diagram of a control system of the copying machine.

FIG. 3 is an explanatory diagram illustrating a change in a charge amount of a developer depending on a leaving time.

FIG. 4 is a flowchart showing an example of aging execution control of the copying machine.

FIG. 5 is an explanatory diagram showing a relationship between a difference between an image density of a reference toner image and a preset target value of the image density and an aging time required for a charge amount to reach a saturated state.

FIG. 6 is an explanatory diagram illustrating a temperature change from when a fixing heater is turned on to when a temperature of a fixing roller reaches a temperature at which a copying operation is possible.

FIG. 7 is a flowchart illustrating an example of remaining aging operation execution control.

FIG. 8 is an explanatory diagram showing a change over time of a charge amount of a developer.

FIG. 9 is a flowchart showing another example of aging operation execution control.

FIG. 10 is a graph showing a relationship between a development potential and a toner adhesion amount per unit area (hereinafter, simply referred to as “toner adhesion amount”).

FIG. 11 is a flowchart showing still another example of the aging operation execution control.

FIG. 12 is an explanatory diagram illustrating a relationship between a toner consumption amount and a charge amount of a developer.

FIG. 13 is an explanatory diagram illustrating a relationship between a difference ΔMp between a detected image density value of a reference toner image and a preset target value of the image density, and a toner consumption amount during an aging operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 Charger 3 Exposure 4 Developing roller 5 Stirring roller 6 Toner supply device 7 Developing device

Claims (4)

[Claims] An image carrier, a developing device for developing a latent image formed on the image carrier with a two-component developer containing a toner and a carrier, and a reference latent image for detection on the image carrier. Forming a reference toner image by developing the reference latent image with the developing device to form a reference toner image; an image density detection unit detecting an image density of the reference toner image; and an image density detection unit Replenishing means for replenishing toner for replenishment in the developing device based on the detection result of the above, and aging operation control means for executing an aging operation of repeating consumption of toner of the developing device and replenishment of toner to the developing device During the warm-up operation before the image forming operation by the image forming apparatus, the reference toner image forming means forms a reference toner image, and the image density detecting means detects the image density of the reference toner image. Based on the result, to perform an aging operation by the aging operation control means,
An image forming apparatus having a stabilization control unit for stabilizing the charge amount of the developer, wherein the toner consumption amount and the toner replenishment amount per unit time set in advance based on the detection result by the image density detection unit. Calculate the period required for stabilizing the developer charge amount assuming that the aging operation is performed by the aging operation control means,
The image forming apparatus is characterized in that the stabilization control means is configured to execute the aging operation only during the set period when the calculated period is equal to or longer than a preset set period. 2. The image forming apparatus according to claim 1, wherein when the calculated period is equal to or longer than a preset set period, the aging operation is performed only during the set period.
The stabilization control means is configured to be executed after the image forming operation started after the image forming operation is enabled for the remaining period or after the next warm-up operation. Image forming apparatus. 3. The image forming apparatus according to claim 1, wherein when the calculated period is equal to or longer than a preset set period, the aging operation is performed only during the set period, and then the reference toner image formation is performed again. Forming a reference toner image by the means, configuring the stabilization control means to detect the image density of the reference toner image by the image density detection means, and, based on a detection result by the image density detection means, An image forming apparatus comprising: a condition changing unit configured to appropriately change an image forming condition at the time of an image forming operation started after the image forming operation is enabled from an image forming condition at a time of normal image forming. 4. A developing device for developing an image carrier, a latent image formed on the image carrier with a two-component developer containing toner and a carrier, and a reference latent image for detection on the image carrier. Forming a reference toner image by developing the reference latent image with the developing device to form a reference toner image; an image density detection unit detecting an image density of the reference toner image; and an image density detection unit Replenishing means for replenishing toner for replenishment in the developing device based on the detection result of the above, and aging operation control means for executing an aging operation of repeating consumption of toner of the developing device and replenishment of toner to the developing device During the warm-up operation before the image forming operation by the image forming apparatus, the reference toner image forming means forms a reference toner image, and the image density detecting means detects the image density of the reference toner image. Based on the result, to perform an aging operation by the aging operation control means,
An image forming apparatus having stabilization control means for stabilizing the charge amount of the developer, based on a detection result by the image density detection means such that the charge amount of the developer is stabilized during the warm-up operation. And a stabilization control unit configured to set a toner consumption amount per unit time when the aging operation is performed.