JP2003057888A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device in which low density in an image can be prevented by detecting the state of toner packing and controlling the image forming state. SOLUTION: In the apparatus, a means to detect an output value corresponding to the quantity of developer existing in a specified part inside the developing device and a means to store the output value are provided and the variation in the distribution of the developer is detected based on the varied quantity of the output value using information from the storing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an electrophotographic image forming apparatus, a cartridge mountable to the main body of the image forming apparatus, that is, a process cartridge, a developing device in the form of a cartridge, and the like. The present invention relates to an image forming apparatus that detects a remaining amount of a developer by using a storage unit mounted in a cartridge, a cartridge that is attachable to and detachable from the image forming apparatus, and an image forming system.

Here, as an electrophotographic image forming apparatus,
Examples include electrophotographic copiers, electrophotographic printers (eg, LED printers, laser beam printers, etc.), electrophotographic facsimile machines, and electrophotographic word processors.

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

[0004]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus, when the toner, which is a developer, runs short during operation, defects such as a decrease in image density and image burning occur. It is equipped with means for detecting and running out of toner when it runs out to warn, and it has been possible to replace the cartridge or replenish the toner before an image defect such as a decrease in image density occurs.

However, as a means for detecting the remaining amount of toner,
For example, a capacitance detection type is known.

FIG. 1 shows a conventional developing device for detecting the capacity.

In the figure, 5 is a developing blade which is a developer regulating member, and 2 is a developing sleeve which is a developer carrying member. In the vicinity of the sleeve provided in the developing device, an antenna element 10 which is a conductive detecting member is provided in parallel with the sleeve.
0 is arranged, and the remaining toner amount is detected by the capacitance value between the developing sleeve 2 and the antenna.

[0008]

However, in the conventional configuration shown in the figure, the antenna for detecting the remaining toner amount is fixedly arranged in the vicinity of the developing sleeve 2, and therefore the following problems occur. Occurred.

That is, when the antenna is fixedly arranged in the vicinity of the developing sleeve 2 as in the conventional case, the toner sinks due to its own weight when left standing for a long time, and the antenna rod 100
There was a case where they were aggregated finely as shown by the shaded area in the figure.

Moreover, in order to improve the accuracy of the remaining amount detection, it is necessary to install the antenna rod 100 near the developing sleeve 2 on the toner circulation path. Therefore, toner packing may occur when there is a large amount of toner remaining.

When toner packing occurs with the antenna 100 as the core, the circulation shown by the arrow in the drawing is obstructed, so that it becomes difficult to supply toner to the developing sleeve 2. Then, when a high-density image is printed, a low-density image may occur.

The present invention has been made in view of the above problems. An object of the present invention is to detect the packing state of toner in a developing device and control the image forming condition to reduce the image density. Developing device that can prevent the problem of
To provide a process cartridge and an image forming apparatus.

[0013]

The first invention according to the present application for achieving the above object is a development for visualizing an electrostatic latent image formed on an electrostatic latent image bearing member with a developer. Means and
A storage unit for storing information on the developing device;
In an image forming apparatus detachably accommodating the developing device, the image forming device having a detecting means capable of sequentially outputting an output depending on a distribution state of the developer in a specific portion in the developing device, and applying a bias voltage to the developing means. The image forming apparatus is characterized in that it has a voltage applying unit and changes the bias voltage applied to the developing unit according to the amount of change in the output.

In the above arrangement, the problem of low image density due to the packing of toner in the developing device can be prevented.

A second invention according to the present application is a process cartridge in which a container accommodating a developer and a developing device are integrally unitized, and an electrostatic latent image bearing feature and an electrostatic latent image bearing feature. A developing unit that visualizes the electrostatic latent image formed on the surface with a developer; and a storage unit that stores information about the process cartridge, and that stores a developer in a specific portion inside the container of the process cartridge. In an image forming apparatus detachably accommodating a process cartridge having a detection unit capable of sequentially outputting an output depending on a distribution state,
The image forming apparatus is characterized in that the developing means has a voltage applying means for applying a bias voltage, and the bias voltage applied to the developing means is changed according to the change amount of the output.

In the above structure, it is possible to prevent the problem of low image density due to packing of toner in the developing device.

In a third aspect of the present invention, the output value of the remaining amount detecting means is obtained by measuring the capacitance between at least two or more electrodes. 2 is the image forming apparatus.

In the above structure, it is possible to prevent the problem of low image density due to the packing of toner in the developing device.

A fourth invention according to the present application is the image forming apparatus according to claim 1, wherein the output value of the remaining amount detecting means depends on the amount of the developer in the developing device.

In the above structure, the problem of low image density due to the packing of toner in the developing device can be prevented, and the amount of developer in the developing device can be detected.

A fifth aspect of the present invention is the image forming apparatus according to claim 2, wherein the output value of the remaining amount detecting means depends on the amount of developer in the process cartridge.

In the above structure, the problem of low image density due to the packing of toner in the developing device can be prevented, and the amount of developer in the process cartridge can be detected.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The image forming apparatus of this embodiment is a laser beam printer which receives image information from a host computer and outputs an image. Consumable items such as a photosensitive drum and toner are detached from the main body as a process cartridge. This is a replaceable image forming apparatus.

The structure of this embodiment will be described with reference to FIGS.

As shown in FIG. 1, the process cartridge C
Is a photoconductor 1, a charging roller 7 for uniformly charging the photoconductor 1, a developing device 4 including a developing sleeve 2 as a developing unit arranged opposite to the photoconductor 1, a cleaning unit 8, and a cleaning unit. A waste toner container 9 which is a cleaner for containing the residual toner removed from the photoconductor 1 by the means 8 is integrally configured.

Further, as shown in FIG. 2, in the laser printer 14 which is an image forming apparatus, a laser scanner 11 for irradiating a laser beam 10 corresponding to image information is provided above the process cartridge C, and a laser scanner 11 is provided below the process cartridge C. A transfer roller 12 facing the body 1 is provided.

In the above arrangement, the photosensitive member 1 is the charging means 7
Is uniformly charged, and the surface thereof is scanned and exposed by the laser light 10 emitted from the laser scanner 11 on the image portion of the photosensitive drum to form an electrostatic latent image of desired image information. The electrostatic latent image is visualized as a toner image by the toner T in the toner container 4 being attached by the action of the developing roller 2.

In this embodiment, the insulating magnetic material 1
A component toner was used. The image on the photoconductor 1 is transferred by the transfer unit 1.
2 is transferred to the recording paper. The recording paper passes through the fixing means 13 to fix the image on the recording paper, and is discharged to the outside of the main body.

The developing sleeve 2 according to the present invention is composed of a hollow non-magnetic metal sleeve, and has a magnet roller therein. A bias voltage having an AC voltage component obtained by superimposing an AC voltage on a DC voltage is applied to the developing sleeve 2 by a developing bias power source, which causes the toner to oscillate in the developing region to cause an image portion on the photosensitive drum. Let it adhere and remain.

However, in order to prevent fog on the non-image area of the photosensitive drum, the DC bias component must be set between the potential of the latent image area and the potential of the non-image area. In the present invention, the dark portion potential of the latent image is -600V and the light portion potential is -100V.

As a direct current voltage component of the developing bias voltage −
The voltage is set to 300 V to -500 V, the peak-to-peak voltage is 1600 V, and the frequency is 1800 Hz as the AC component.

According to the present invention, the laser beam printer 1
Reference numeral 4 has a developer amount detecting device provided with a developer remaining amount detecting means capable of sequentially detecting the remaining amount of the toner T as it is consumed.

In this embodiment, a conductive antenna rod 100 is provided as a developer remaining amount detecting means. As shown in FIG. 1, an antenna rod 100 is provided at a position facing the developing sleeve 2 over the entire area in the longitudinal direction of the developing device.

The antenna element 100 can be used without particular limitation as long as it is a material capable of flowing an electric current.

FIG. 3 shows a circuit configuration for detecting the amount of toner in the process cartridge. As for the toner amount, when a predetermined AC bias is output from the developing bias circuit 104 as the developing bias applying unit, the applied bias is applied to the reference capacitor 105 and the developing sleeve 2. Voltage V across the reference capacitor 105
1 is generated, and a current corresponding to the electrostatic capacitance flows between the developing sleeve 2 and the antenna rod 100. This current value is converted into the voltage V2 by an arithmetic expression.

The detection circuit 109 generates a voltage V3 from the voltage V1 generated across the input reference capacitor 105 and the potential pressure difference V2 between the developing sleeve 2 and the antenna 100, and outputs the voltage V3 to the AD converter 110. . AD
The conversion unit 110 outputs the result of digital conversion of the analog voltage V3 to the main body control unit 22. In the main body control unit 22,
Based on the voltage value converted into the digital value, the remaining toner level is determined by using the calculation unit 24, the control unit 25, and the remaining developer amount determination table 27 shown in FIG. 4 described later in detail.

Here, in the following description, the signal finally output by the antenna 100 according to the electrostatic capacitance between the developing sleeve 2 and the antenna rod 100 is simply referred to as "from the residual developer amount detecting means". Signal ”,“ detection value of developer remaining amount detecting means ”, and the like.

Further, the main body control section 22 obtains the remaining percentage of the toner based on the detected remaining amount of toner, and the information is displayed on the display means 27 of the main body of the apparatus, or the toner is so large that it is impossible to form an image of a predetermined quality. A "toner-less" warning is displayed to notify the user that something has gone awry.

The voltage value detected by the main body controller 22 of the image forming apparatus main body based on the developer remaining amount detecting means of this embodiment is simply referred to as "detection voltage value V3". This detected voltage value V
The toner remaining amount is determined using the toner remaining amount determination table from 3 to 6.

The vertical axis in FIG. 5 represents the detected voltage value V3 corresponding to the electrostatic capacitance values of the developing sleeve 2 as the residual developer amount detecting means and the antenna rod 100, and the horizontal axis represents the residual toner in the developing device. Indicates the amount. The remaining toner amount in the process cartridge is determined by comparing the detected voltage value with the developer remaining amount determination table determined by the ideal curve. Further, in the present embodiment, the toner amount determination table 25 is stored in the main body control unit 22 in advance.

Further, when the amount of toner remaining in the developing device is 50 g or less, it is set that a "toner-less" warning is displayed because a blank image may occur. Capacitance, detection voltage) = (13pF, 1.0V), (18
pF, 0.8 V), the decreasing / increasing relationship between the electrostatic capacity between the developing roller 2 and the antenna rod 100 and the detection voltage is opposite, and is detected by the developer remaining amount detecting means. At this time, the detection voltage is set to be small when the capacitance is large, and the detection voltage value is set to be large when the capacitance is small.

The image forming apparatus main body converts the electrostatic capacitance value detected by the toner remaining amount detecting means into a voltage and outputs the voltage as shown in FIG. When the toner is not in the developing container, the detected voltage value shows the maximum value, and the electrostatic capacitance shows the minimum value.

In this embodiment, since the developing roller 2 and the antenna rod 100 that is relatively close to the developing roller 2 are used as the developer remaining amount detecting means, FIG. As shown in FIG.
The decrease in the detected voltage starts when the consumption is less than g,
After that, the remaining amount of the developer within the range until the developer runs out can be sequentially detected.

However, the shape of the antenna is not limited to the rod shape, and as the antenna which is the developer remaining amount detecting means, for example, the input side electrode and the output side electrode which are sheet metal as in the present embodiment are provided in the developing device. It is naturally possible to provide a structure in which the range from the time when the remaining amount of the toner is large to the time when the remaining amount of the toner is exhausted can be sequentially detected by arranging it at any position.

However, in the structure of the above-mentioned remaining amount detecting means, the antenna for detecting the remaining amount of toner is fixedly arranged in the vicinity of the developing sleeve 2, so that the following problems occur.

That is, when the antenna is fixedly arranged in the vicinity of the developing sleeve 2 and the toner is settled by its own weight when left standing for a long time, the antenna rod 100 serves as a core to make the toner dense as shown by the hatched portion in FIG. There were times when it aggregated.

Moreover, in order to improve the accuracy of the remaining amount detection, it is necessary to install the antenna rod 100 near the developing sleeve 2 on the toner circulation path. Therefore, toner packing may occur when there is a large amount of toner remaining.

When toner packing occurs with the antenna 100 as the core, the circulation shown by the arrow in the drawing is obstructed, so that it becomes difficult to supply toner to the developing sleeve 2. Then, when a high-density image is printed, a low-density image may occur. The toner amount of becomes large. Therefore, when the electrostatic capacity value at the time of the last printing and the current electrostatic capacity toner are packed, it is possible to detect the presence / absence of the packing of the toner by comparing the sleeve antenna dedicated space amount value.

Therefore, in the present embodiment, 1. The process cartridge is provided with the memory 20, and the detection voltage value detected in the image forming apparatus main body is used to detect the remaining toner amount at the time of rotation after printing, and the detection voltage value is stored in the memory 2.
Store at 0.

2. When the detected voltage value during the pre-printing rotation is smaller than the detected voltage value stored in the memory 20 by 0.2 V or more, the process condition is changed as a measure against the image density.

3. If the detected voltage value during rotation after printing is larger than the detected voltage in the memory 20, the memory 20
The value of the detected voltage value in is updated.

The following control is performed. As a result, a stable image can be obtained by detecting the toner packing state of the cartridge and controlling the process conditions.

First, the memory 20 provided in the process cartridge will be described.

As shown in FIGS. 1 to 3, the cartridge C according to this embodiment has a memory 20 on the side surface of the waste toner container 9 and a cartridge-side transmission section for controlling reading and writing of information from and to the memory 20. 21. When the cartridge is mounted in the image forming apparatus, the cartridge transmission unit 23 and the control unit 24 on the image forming apparatus side are arranged to face each other. The main body control unit 24 also includes a function as a transmission unit on the main body side.

Further, the memory 20 is installed on the cleaner container 9 side, but this is the direction in which the cartridge C is inserted into the image forming apparatus 14 with the cleaner container 9 side first, so that the memory device 20 and the image are stored. This is because it is taken into consideration to facilitate the alignment with the communication means on the forming device 14 side.

As the memory 20 used in the present invention,
An ordinary semiconductor electronic memory 20, such as a combination of the non-volatile memory 20, the volatile memory 20 and a backup battery, can be used without particular limitation.

In particular, the memory 20 and the read / write I
In the case of a non-contact memory that performs data communication between Cs by electromagnetic waves, contact between the transmission unit 23 and the main body control unit 24 may be non-contact, so that there is no possibility of contact failure due to the mounting state of the cartridge, and reliability is improved. Highly controllable. In this embodiment, a non-contact type memory 20 is used as the memory.

These two control units constitute a control means for reading and writing information in the memory. Regarding the capacity of the memory 20, it is assumed that the memory 20 has a capacity sufficient to store a plurality of pieces of information such as a cartridge usage amount and a cartridge characteristic value described later. In the memory 20, the used amount of the cartridge is written and stored as needed.

Next, the procedure for detecting the remaining amount of toner will be described with reference to the flowchart of FIG.

In FIG. 6, the preparatory rotation means that the main switch for connecting the image forming apparatus to an external power source is turned on, the fixing device 19 is heated and its warm-up is completed, or after the cartridge is replaced. This is an operation for rotating the photosensitive drum 1 and cleaning the photosensitive drum 1 and the transfer roller 12.

Further, the pre-rotation is an operation caused by a print start command, and at the same time when the photosensitive drum 1 rotates, the roller charger 12 is actuated to adjust the sensitivity of the photosensitive member 1.
This is an operation for uniformizing charging and cleaning.

Further, the post-rotation means that the rotation of the photosensitive drum 1 is continued for a predetermined time even after the printing is finished, and the roller charger 12
Is an operation for canceling the sensitivity history of the photoconductor 1 and the like.

First, the main body power is turned on (STEP
1) When the fixing unit 13 is warmed up and the image forming apparatus is ready for printing, preparatory rotation is performed (STEP 2). During the preparatory rotation, the developing bias is applied (ON) and the remaining toner amount is detected (S
TEP3). In STEP 3, when the toner-out state (toner-out state) is detected, the toner-out warning display is displayed (STEP 4), and otherwise, the standby state for the print start command is entered (STEP 5). Then, when the cartridge (CRG) is replaced during standby, preparation rotation and toner remaining amount detection are performed again when a new cartridge is mounted, and the process returns to standby.

When a print start command is input during the standby (STEP6), printing is performed following the previous rotation (STEP7) (STEP8). At the time of pre-rotation after the end of printing, the developing bias is applied and the remaining toner amount is detected. When the detected voltage at this time is smaller than V3 in the memory described later by 0.2 V or more, the developing bias is changed from the default value because the toner is in the packing state (STEP 9). After printing (STEP 10), post-rotation is performed (STEP 11). The post-rotation is an operation for continuing the rotation of the photosensitive drum 1 for a predetermined time even after the printing is completed and operating the charging roller 7 to eliminate the sensitivity history of the photoconductor 1. At the time of post-rotation after printing, the remaining toner amount is detected in the same manner as described above (STEP 11).

Then, the V stored in the memory at the time of post-rotation
If the detected V3 value is greater than 3, then V3 in memory
The value is updated (STEP 12). After that, the system again enters a standby waiting for a print start command (STEP 8).

As described above, in this embodiment,
When the toner packing was detected, the voltage value of the DC component of the developing bias was changed. The present invention is not limited to this. For example, Vpp of the AC component of the developing bias, the frequency of the developing bias, the charging bias, etc. may be used.

[0067]

As described above, according to the first invention of the present application, the developing means for visualizing the electrostatic latent image formed on the electrostatic latent image carrier by the developer, An image forming operation is carried out by removably accommodating the developing device having a storage device for storing information about the developing device and a distribution condition detecting device capable of sequentially detecting the distribution condition of the developer in a specific portion of the developing device. In the electrophotographic image forming apparatus to be performed, by using the electrophotographic image forming apparatus characterized by having control means for changing the process condition of the image formation according to the information from the distribution state detection means Can be suppressed.

According to the second invention of the present application,
A process cartridge in which a container containing a developer and a developing device are integrally unitized, and an electrostatic latent image carrier,
The electrostatic latent image formed on the electrostatic latent image carrier is visualized by a developer, and the storage unit stores information about the process cartridge. The developing unit is provided in a specific portion of the process cartridge. In an electrophotographic image forming apparatus for detachably accommodating the process cartridge having a distribution state detecting unit capable of sequentially detecting the distribution state of the developer and performing an image forming operation, an image forming process based on information from the distribution state detecting unit. By using the electrophotographic image forming apparatus characterized by having the control means for changing the condition, it is possible to suppress the image adverse effect due to the change of the distribution state.

According to the third invention of the present application,
By using the image forming apparatus according to the first and second aspects, the image forming process condition is a bias applied to the developing unit, and it is possible to suppress the image adverse effect due to the change of the distribution state.

According to the fourth invention of the present application,
The distribution state detecting means is composed of a means for detecting an output value corresponding to the amount of the developer existing in the specific portion and a means for storing the output, and based on the change amount of the output value by the information from the storing means. By using the image forming apparatus according to the first aspect, which detects a change in the distribution of the developer, it is possible to suppress the adverse effect on the image due to the change in the distribution state.

According to the fifth invention of the present application,
The image forming apparatus according to claim 4, wherein the capacitance between at least two electrodes is measured as means for detecting the output corresponding to the amount of the developer in the specific portion. It is possible to suppress the adverse effect on the image due to the change in the state.

[Brief description of drawings]

FIG. 1 is a sectional view of a process cartridge according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the process cartridge image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram for detecting the amount of toner in the process cartridge according to the first exemplary embodiment of the present invention.

FIG. 4 is a block diagram of main body control unit information according to the first embodiment of the present invention.

FIG. 5 is a relationship between the remaining toner amount and the detected voltage in the related art according to the first embodiment of the present invention.

FIG. 6 is a toner remaining amount determination table according to the first embodiment of the present invention.

FIG. 7 is a sectional view of the developing device according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing an operation sequence according to the first embodiment of the present invention.

[Explanation of symbols]

1 photoconductor 2 Development sleeve 3 T stirring 4 Toner container 5 Development blade 6 Development bias power supply 7 charging roller 8 cleaning blade 9 Cleaning container 10 laser light 11 Laser unit 12 Transfer roller 13 Fixing unit 20 memory 21 Memory side transmitter 22 Control unit 23 Control unit 24 arithmetic unit 25 Remaining amount detection correction table 26 Body remaining amount detection detector 27 Display means 100 Antenna rod which is the toner level detection means C process cartridge T toner

Claims (5)

[Claims] 1. A developing unit that visualizes an electrostatic latent image formed on an electrostatic latent image carrier with a developer, a storage unit that stores information about the developing unit, and a specific portion in the developing device. The developing device having a distribution state detecting means capable of sequentially detecting the distribution state of the developer in is detachably accommodated,
An image forming apparatus for performing an image forming operation, comprising: a control unit for changing an image forming process condition according to information from a distribution state detecting unit. 2. A process cartridge in which a container accommodating a developer and a developing device are integrally unitized, and an electrostatic latent image carrier and an electrostatic latent image formed on the electrostatic latent image carrier are developed. A developing unit that visualizes with a developer, a storing unit that stores information about the process cartridge, and a distribution state detecting unit that can sequentially detect the distribution state of the developer in a specific portion of the process cartridge. An image forming apparatus for detachably accommodating the process cartridge and performing an image forming operation, comprising: a control means for changing a process condition of image formation according to information from a distribution state detecting means. 3. The image forming process condition is a bias applied to the developing means.
The image forming apparatus described. 4. The distribution state detecting means comprises a means for detecting an output value according to the amount of developer existing in a specific portion and a means for storing the output, and the output value is obtained by the information from the storing means. 4. The image forming apparatus according to claim 1, wherein the change in the distribution of the developer is detected based on the change amount of. 5. The image forming apparatus according to claim 4, wherein the capacitance between at least two electrodes is measured as means for detecting the output corresponding to the amount of the developer in the specific portion.