JPH0651625A - Device for detecting attachment of developing device for electrophotographic image forming device - Google Patents

Abstract

PURPOSE:To evade the failure of toner supply in a state where a developing device slips down by detecting whether or not the developing device is attached by using a magnetic permeability detecting sensor for detecting density. CONSTITUTION:The magnetic permeability detecting sensor is incorporated in the developing device, and the detection signal of the sensor is shaped to a pulse signal. By counting the number of generated pulse signals in a specified gate period, toner concentration is detected. When a power source is turned on and a clamshell is closed in a state where the device idles, the density is detected in order to check the developing device. Concretely, 1st density detecting operation is performed(S2), the result of the operation is stored(S4) and set as initial data for a counter in the case of 2nd density detecting operation(S5). Then, a 1st counted value is compared with a 2nd counted value (S6), and when the pulse signal is not inputted at the of 2nd counting(S9), the slipping-down of the developing device is detected(S10).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the mounting of a developing device in an electrophotographic image forming apparatus, and more particularly to detecting a missing or incomplete setting of the developing device by an output signal from a density detecting magnetic permeability detecting circuit. And a developing device mounting detection device.

[0002]

2. Description of the Related Art In many cases, a toner developing device in an electrophotographic image forming apparatus forms a unit, and the unit is removable from the main body of the apparatus. This is because the developing device can be attached and detached as a unit to facilitate maintenance, inspection, and cleaning of the unit and the image forming apparatus main body.

Further, in the case of a color electrophotographic image forming apparatus, the developing device is integrated with a maximum of four developing devices using cyan (C), magenta (M), yellow (Y) and black (BL) toners. There are two types, one of which is a single unit and the other is a unit of which each of the maximum four developing devices is addressed.

[0004]

As described above, the method in which the developing unit is configured to be attachable to and detachable from the main body of the electrophotographic image forming apparatus has many advantages, and is widely adopted. Since it is possible, the developer unit may be forgotten to be attached, or even if it is attached, the attachment may be incomplete.

If there is no mechanism for checking the improper mounting of the developing device as described above, there is a possibility that toner may be replenished from the toner replenishing device when the developing device is in a detached state or incompletely mounted state. The above-mentioned defective mounting of the developing device is likely to occur frequently when a plurality of developing device units are mounted as in the case of multicolor. Further, even when the check mechanism is provided, if the check mechanism is provided for each of the plurality of developing device units, the arrangement of the check mechanism becomes complicated and the cost also increases.

The present invention has been made in view of the above-mentioned problems, and it is possible to detect whether or not the developing device is mounted by utilizing a density detection circuit using a magnetic permeability detecting sensor for density detection built in the developing device. An object of the present invention is to provide a device and to avoid a problem such as toner replenishment in a state where a developing device is pulled out with a simple configuration.

[0007]

Therefore, according to the present invention, a developing device is detachably mounted, and the developing device internally detects a change in magnetic permeability depending on the amount of toner as a frequency change of a resonance circuit. Detection of mounting of a developing device in an electrophotographic image forming apparatus having a magnetic susceptibility detection sensor, shaping a detection signal from the sensor into a pulse signal, and detecting density based on the number of pulse signals generated within a predetermined gate period The apparatus is configured to detect whether or not the developing device is attached based on whether or not the pulse signal is input within the predetermined gate period.

Here, during idling of the electrophotographic image forming apparatus, when the power is turned on, and at least when the cover that is opened / closed at the time of maintenance / inspection of the developing device is closed,
It is preferable to detect whether or not the developing device is attached. Further, during the image forming operation of the electrophotographic image forming apparatus,
For toner replenishment control, density detection is repeatedly performed based on the count of the number of pulses generated in the predetermined gate period,
In the density detection for the toner replenishment control, it is preferable to determine that the developing device is disconnected when the pulse signal is not continuously input a predetermined number of times or more.

[0009]

The density detecting magnetic permeability detecting sensor is built in the developing device, and the density is detected based on the number of pulses generated within a predetermined gate period of the pulse signal obtained by shaping the detection signal from the sensor. . Here, if the developing device is not attached, or if the developing device is incompletely attached even if it is attached, the detection signal from the sensor will not be input, so no pulse will be input within the predetermined gate period. If the developing device is pulled out, it is possible to detect the removal of the developing device.

When the developing device is removed after the power is turned on,
Since the maintenance / inspection cover is opened, if opening / closing of the cover is detected and the mounting state is detected when the cover is closed, it is possible to reliably detect the removal of the developing device after the power is turned on. it can. In addition, there is a case where the developing device is pulled out by opening the cover before turning on the power, so that detection is performed when the power is turned on.

Further, during the image forming operation, when the density detection based on the count of the number of pulses generated within the predetermined gate period is repeatedly performed for toner replenishment control, a separate pulse is detected for detecting the mounting of the developing device. Instead of counting the number of occurrences, the mounting state of the developing device is detected during the density detection operation for toner replenishment control.

[0012]

EXAMPLES Examples of the present invention will be described below. Figure 1
1 shows a configuration of an electrophotographic image forming apparatus provided with a developing device mounting detection device of the present invention. In this figure, a drum-shaped image bearing member, that is, a photosensitive drum 10 is driven and rotated clockwise in FIG. Further, 20 is a charger for applying an electric charge to the photoconductor on the peripheral surface of the photoconductor drum 10, and 30 is a laser writing unit constituting an exposure optical system.

When a laser writing signal is input to the laser writing unit 30, the laser writing unit
In 30, a laser beam generated by a semiconductor laser (not shown) is rotationally scanned by a polygon mirror 32 which is rotationally driven by a drive motor 31, and passes through an fθ lens 33 to form an optical path by three mirrors 34A, 34B and 34C. A photoconductor drum that has been bent and to which electric charges have been previously applied by the charger 20.
It is projected on the surface of 10.

On the other hand, when the scanning is started, the laser beam is detected by the index sensor, the modulation of the laser beam by the first color signal is started, and the modulated laser beam moves on the peripheral surface of the photosensitive drum 10. To scan. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photoconductor drum 10 by the main scanning by the laser beam and the sub-scanning by the rotation of the photoconductor drum 10. This latent image is developed by a developing means that contains, for example, a yellow developer as a first color, and a yellow toner image is formed on the peripheral surface of the photosensitive drum 10. The toner image obtained in this way passes under the cleaning means separated from the peripheral surface of the photosensitive drum 10 while being held on the peripheral surface of the photosensitive drum 10, and enters the next image forming cycle.

That is, the photosensitive drum 10 is the charger.
The second color signal is recharged by 20, and then the second color signal is input to the laser writing unit 30, and the second color signal is written on the peripheral surface of the photosensitive drum 10 in the same manner as in the case of the first color signal described above. And a latent image is formed. This latent image is developed by a developing unit that contains, for example, a magenta developer as the second color, and a magenta toner image is formed. The magenta toner image is formed on the previously formed yellow toner image.

The toner image obtained in this way passes under the cleaning means separated from the peripheral surface of the photosensitive drum 10 while being held on the peripheral surface of the photosensitive drum 10 to form the next image. Enter the cycle. Similarly, writing by the third color signal is performed on the photosensitive drum 10,
A latent image is formed. This latent image is developed by developing means containing a developer of, for example, cyan as a third color,
A cyan toner image is formed. The cyan toner image is formed on the yellow and magenta toner images described above.

As described above, a color toner image is formed on the photosensitive drum 10 by superimposing the three color toner images. Similarly, by superimposing the black toner image further, a high quality color image is obtained. Will be done. 611A,
611B, 611C, and 611D are developing devices as developing means that contain the yellow, magenta, cyan, and black developers that perform the above-described development.

The developing units 611A, 611B, 611C and 611D are
As shown in the example of the developing device 611A, a developing roller (developing sleeve) 612 having magnetic poles fixed inside and facing the peripheral surface of the photosensitive drum 10 at a predetermined interval, and conveying in opposite directions. A pair of agitating rollers 614 and 615 having a force are provided, and by the mixing action of the agitating rollers 614 and 615, the developer is made uniform in toner and carrier components, and the developing roller 612 is rotated around the rotating developing roller 612. Is supplied to the surface.

In this electrophotographic image forming apparatus, a two-component developer composed of toner and carrier is used, and its mixing ratio, that is, its concentration must be kept proper and constant. Therefore, in order to replenish the toner amount commensurate with the consumed toner while detecting the mixed density, the magnetic permeability detection sensors 641A, 641B, 64 which detect the magnetic permeability of the magnetic developer.
1C, 641D is a container 60 of each developing device 611A, 611B, 611C, 611D.
It is installed in 3A, 603B, 603C, 603D, and its connection terminals are provided as connection terminals on the surface of the container 603 of each developing device, and when the developing device is mounted in the regular position, the connection on the developing device side is made. The terminal and the terminal provided at the developing device mounting position on the main body side are electrically connected, and the sensor output is attached to the frame 701 of the clamshell opening / closing section (cover) 700. Output).

The magnetic permeability detection sensors 641A, 641B, 641C,
The 641D has a passage provided at a position where the developer flows in each developing device, and induces the developer to pass through the coil of the resonance circuit.
The amount of carriers that are magnetic particles flowing in the magnetic field decreases when the toner is large, and increases when the toner is small, and the inductance changes. In order to detect this change in magnetic permeability, that is, the inductance with high sensitivity, it is considered as the frequency change (f = 1 / 2π (LC) ^1/2 ) of the resonance circuit, and the frequency signal corresponding to the concentration output from the sensor is converted into a pulse signal. Shape the frequency, detect the frequency by the number of occurrences of the pulse signal within a predetermined gate time, detect the toner concentration based on the frequency (pulse number), and control the toner replenishment so that the toner concentration becomes constant. It is a method to do.

Specifically, as shown in FIG. 2, the detection signals from the magnetic permeability detection sensors 641A, 641B, 641C, 641D are
It is input to the analog multiplexer 650, and the analog multiplexer 650 outputs the output of the corresponding sensor to the buffer transistor 652 based on the color designation signal from the CPU 651. The analog multiplexer
The magnetic permeability detection circuit 640 is composed of 650 and the buffer transistor 652.

The sensor output through the buffer transistor 652 is input to the comparator 653, where it is shaped into a pulse signal. The pulse signal is a counter A654
When the gate of the counter A654 is opened for a predetermined period (for example, 12 msec), the number of pulses within that period is counted by the counter A654, and the frequency of the detection signal from the sensor, that is, , Concentration is detected.

A counter B65 to which the clock signal from the oscillator 655 is input for a predetermined period when the gate is opened.
Controlled by 6. The above-mentioned comparator 653, counter A 654, counter B 656, and CPU 651 constitute a toner replenishment control circuit 657. In the actual density detection, for each color, counting the number of pulses in the gate period is repeated about 20 times, the peak value of the sampling data at the 20 times is obtained, and the peak value is obtained in the initial state of the developing device. The calculation of the toner density by comparing with the level is repeated during the printing operation. Then, replenishment of toner is controlled so that the detected toner density approaches the reference level. The 20 times are set to repeat the concentration detection for a period longer than the frequency fluctuation cycle of the sensor detection signal.

On the other hand, the recording sheet carried out from a sheet feeding cassette (not shown) is fed by a sheet feeding roller 61 to a sheet feeding guide 72.
Along with the toner image, the toner image is temporarily stopped, and the toner image is conveyed again in synchronism with the rotation of the photoconductor drum 10 having the toner image and is sent to the transfer portion in synchronization with the peripheral speed of the photoconductor drum 10.
Reference numeral 80 denotes a rotatable transfer roller, which is charged with a voltage applied thereto, and constitutes a transfer unit for transferring a toner image to the recording paper side via a conveyor belt 80B at a contact point with the peripheral surface of the photosensitive drum 10. To do. The transfer roller 80 is a drive roller 80.
A conveyor belt 80B is stretched between A and A, and the transfer is performed while the recording paper is conveyed by the conveyor belt 80B. 80
C is a cleaning means for cleaning the surface of the conveyor belt 80B.

Reference numeral 90 is a front band electrode, which is a cleaning device 10.
It is located upstream of 0 and is charged so that residual toner on the peripheral surface of the photosensitive drum 10 on which the toner image is transferred onto the recording paper can be easily removed. Further, 110 and 120 are the cleaning device 100.
The cleaning unit is a conductive bristle brush and a conductive collecting roller, and 130 is a waste toner collecting unit for containing the toner collected by the cleaning unit.

The photosensitive drum 10 that has passed through the front electrode 90 is
The residual toner is removed by the conductive bristle brush 110 brought into sliding contact with a signal from the controller, and the residual toner adhering to the conductive bristle brush 110 is adsorbed by the conductive collecting roller 120. After that, the waste toner collecting unit 13
Sent to 0. The waste toner collecting section 130 is provided with a waste toner feeding rod 131 and a toner collecting bag 132, and the residual toner sent by the collecting roller 120, that is, the waste toner, passes through the waste toner feeding rod 131. And is stored in the toner collection bag 132.

The photosensitive drum 10 whose peripheral surface is thus cleaned is charged again by the charger 20.
Moving on to the formation of a new image, at the same time the conductive bristle brush 11
When 0, the sliding contact state is released. On the other hand, the recording paper on which the toner image has been transferred at the transfer portion is separated from the peripheral surface of the photosensitive drum 10 and fed to the fixing device 60. Reference numeral 63 denotes a fixing heat roller pair, and 64 denotes a paper discharge roller pair. The recording paper having the toner fused and fixed by the heat roller pair 63 is discharged from the fixing device 60 by the paper discharge roller pair 64.

By the way, the color developing devices 611A, 611B,
The 611C is integrally housed in the frame of one cartridge, and is integrally mounted by being guided by the guide rails 713A and 713B, and is provided in the frame 701 of the clamshell opening / closing unit 700. It is removable from the entrance window. Of course, each color developing device may be detachably mounted as an independent cartridge. On the other hand, the developing device 611D containing the black developer is a guide rail.
Fitted along the 713C, again the clamshell closure
It can be attached and detached through the entrance / exit window provided on the 700 frame 701.

That is, each developing device 611A, 611B, 611C, 611D
Is configured so that it can be attached / detached only when the clamshell opening / closing unit 700 is opened, and each developing device 611A, 611B,
Toners are conveyed to 611C and 611D from a toner replenishing tank (not shown) via a toner replenishing device. in this way,
Each of the developing devices 611A, 611B, 611C, 611D is configured to be attachable / detachable to / from the main body, and there is a possibility that the developing device may be forgotten to be attached or may be incompletely attached. If the clamshell opening / closing part 700 is closed and the normal operation is started in such a state that the developing device is not properly attached, toner is replenished to the developing device that is not attached, and the developing device is not attached. The mounting space, and further the entire image forming apparatus is contaminated by the toner dripping.

Further, if the developing process is continued with the developing device imperfectly mounted, the gap between the photosensitive drum 10 and the developing sleeve will be misaligned, and the toner japping effect will be abnormal and the image quality will be deteriorated. Becomes worse. Also, if the toner is imperfectly attached, the toner supply path may be misaligned with the toner receiving port of the developing device, and the toner inlet may be reduced or blocked. May become unstable, power supply may become impossible due to inability to supply, and a hose for replenishing toner, a spiral member for transporting toner, and the like may be damaged.

Therefore, each developing device 611A, 611B, 611C, 611D
It is necessary to have a device for checking whether or not the toner is securely installed. However, if these checking devices are provided independently of the toner density control for each developing device, each sensor will be installed and a new circuit will be installed. Since two systems are provided for each developing device, the apparatus becomes complicated, it becomes difficult to maintain, and the cost increases, so that both can be used in combination.

The contents of detecting the mounting state of the developing device using the above density control system will be described with reference to the flowcharts of FIGS. 3 and 4. In the flowchart of FIG. 3, when the electrophotographic image forming apparatus is in the idling state, interruption is executed when the power is turned on and when the clamshell opening / closing unit 700 is closed.

First, initial dummy data (for example, ffffH for a 16-bit counter) is set in the counter A654 which counts the detection pulse signal from the magnetic permeability detection sensor 641 (S1). Next, start the counter B656,
The gate of the counter A654 is opened for 500 μsec (S2), and the number of pulses of the detection pulse signal generated during the gate open period is counted by the counter A654.

Here, after delaying for a predetermined time (for example, 10 msec) (S3), the count data of the counter A654 is read, the count data is temporarily stored in the buffer memory 1 (S4), and the stored data is stored. The counter A654 is set (S5). Next, start the counter B656 again and set the gate of the counter A654 to 500 μ.
It is opened only for sec (S6), and the number of pulse generation of the detection pulse signal in the gate open period is counted by the counter A654.

After delaying for a predetermined time (S
7) The count value set in the counter A654 is compared with the first count value stored in the buffer memory 1 (S8). Here, the counter A65
When the count value set in 4 is the same as the first count value stored in the buffer memory 1 (S9), the detection pulse signal is input when the gate is opened at least the second time. Indicates that there was no In this case, it is determined whether the developing device corresponding to the read magnetic permeability detection sensor 641 is missing (or incompletely set) (S1
0) The judgment result is displayed on the display unit provided in the electrophotographic image forming apparatus to prompt the inspection of the developing device, and the printing is disabled so that the toner replenishing operation is prohibited.

When the count value set in the counter A654 and the first count value stored in the buffer memory 1 are different (S9), the gate is opened at least the second time. , Indicates that the detection pulse signal input is correct. In this case, it is determined that the developing device corresponding to the read magnetic permeability detection sensor 641 is properly mounted (S11).

The above determination is repeated for each sensor (for each color), and if even one developing device is missing, that fact is displayed to warn, and the print and toner replenishing operations are not performed. To do so. In the case of this embodiment, three color developing devices are integrally mounted, and a black developing device is separately mounted, so that the color developing device is removed or the black developing device is removed. It is good to display it so that it is possible to determine whether or not it is. When three color developing devices are integrally mounted, for example, a magnetic permeability detecting sensor 641 incorporated in one color developing device and a magnetic permeability detecting sensor 641 incorporated in a black developing device are provided. The determination process may be performed only for one sensor.

Here, if the above determination is made when the power is turned on and when the clamshell opening / closing unit 700 is closed, the omission of the developing device can be surely detected without waste. That is, the clamshell opening / closing section 700 must be opened during maintenance and inspection of the developing device.Therefore, when the clamshell opening / closing section 700 is closed, whether the detection signal from the magnetic permeability detection sensor 641 is input or not is determined. If it is determined, it is necessary to detect the omission of the developing device after the maintenance and inspection of the developing device. However, if maintenance is performed on the developing device while the power is off, the power will be turned off.
In the F state, the density detection mechanism does not work, so it is not possible to detect even if the developing device is disconnected. Therefore, immediately detect the disconnection of the developing device when the power is turned on, and check if the developing device was not removed when the power was off. .

On the other hand, during the printing operation, since the density detection using the counter A654 is repeatedly performed for the toner replenishment control, the density detection result is used to detect the developing device omission. The flowchart of FIG. 4 is executed by interruption at every sampling timing (for example, every 15 msec) of the density detection data for controlling toner supply during printing.

First, the check counter for missing the developing device is 0.
It is determined whether or not (S21). In this embodiment, concentration detection (pulse count by gate open) is continuously performed 20 times, and the average of the peak values among the 20 concentration detection results is used as the final concentration detection value. Cage,
Density detection with such 20 times of density detection as one cycle is repeated for each color during the printing operation. Here, since the developing device missing check is performed using the result of the density detection for the normal toner replenishment control, the developing device missing check counter corresponds to the number of times the density detection is performed 20 times.

When it is determined that the developing device missing check counter is 0, the check counter is set to 20.
The process proceeds to a step (S29) for determining whether or not the above is true, but of course a negative determination is made here, and then the check counter is incremented (S30). Then, the initial dummy data (for example, ffffH) is set in the counter A654 (S31), and the same initial dummy data is stored in the buffer memory 2 (S32).

Next, the counter B656 is activated and the gate of the counter A654 is opened for 12 msec (S3
3) The number of pulses of the detection pulse signal generated in the gate open period is counted by the counter A654. When the interrupt is executed next time, similarly, it is first determined whether or not the check counter is 0, but since it is not 0 due to the increment at the previous execution,
Here, the count data of the counter A654 is next read and compared with the contents of the buffer memory 2 (S22).

When the contents of the buffer memory 2 and the count data of the counter A654 are different (S2
3), the count value of the counter A654 is read and stored in the buffer memory 2 as density detection data for toner replenishment control (S24). Then, an error counter described later is cleared (S25). On the other hand, if the contents of the buffer memory 2 and the count data of the counter A654 are the same (S23), it means that the pulse signal did not come in even if the gate of the counter A654 was opened during the previous execution. The error counter is incremented (S26).

When the error counter is incremented, it is then determined whether or not the value of the error counter has reached a predetermined value (for example, 5) (S27). The omission is determined (S28). That is, the error counter is cleared when the detection pulse signal from the magnetic permeability detection sensor 641 is input and the counter A654 counts within the gate open period, so that the detection pulse signal is not continuously input. Only for the case where the developing device is disconnected.

When it is determined that the developing device is missing during printing, the same operation as that for determining the missing during idling such as warning display and toner replenishment operation prohibition is performed after the work in progress is finished and then the printing operation is stopped. do. If the error counter is not incremented to the specified value, the developer missing check counter is set to the maximum value.
It is determined whether or not it has been incremented to 20 (S
29) If not 20, the check counter is incremented (S30), the dummy data is set in the counter A654 (S31), the same dummy data is stored in the buffer memory 2 (S32), and the gate is turned on again. Open to count detection pulse signals (S3
3).

When the check counter is incremented to 20 without continuously incrementing the error counter a predetermined number of times or more, it is determined that the developing device is properly mounted, and the developing device omission check counter is determined. Is cleared to 0 (S34), and the process ends. When the developing device omission is determined and the omission warning is displayed, when the clamshell opening / closing part 700 is opened or closed, or when the power is turned on again, the development device omission is checked again. The unplugged condition is released.

[0047]

As described above, according to the present invention, the density detecting circuit using the density detecting magnetic permeability detecting sensor built in the developing device for controlling toner replenishment is diverted to determine whether the developing device is mounted or not. Can be detected, the toner replenishing operation in the state where the developing device is disconnected can be avoided in advance, and
There is an effect that the structure does not become complicated due to the detection of the developing device omission and an increase in cost can be avoided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an electrophotographic image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a density detection circuit.

FIG. 3 is a flowchart showing the detection of the mounting of the developing device during idling.

FIG. 4 is a flowchart showing detection of mounting of a developing device during printing.

[Explanation of symbols]

 611A, 611B, 611C, 611D Developer 641A, 641B, 641C, 641D Permeability sensor 650 Analog multiplexer 651 CPU 652 Buffer transistor 653 Comparator 654 Counter A 655 Oscillator 656 Counter B 700 Clamshell opening / closing part

Claims (3)

[Claims] 1. A developing device is detachably mounted, and the developing device internally has a density detecting magnetic permeability detecting sensor for detecting a change in magnetic permeability depending on an amount of toner as a frequency change of a resonance circuit. Is a developing device mounting detection device in an electrophotographic image forming apparatus configured to shape the detection signal from the pulse signal into a pulse signal, and detect the density based on the number of occurrences of the pulse signal within a predetermined gate period. A developing device attachment detecting device in an electrophotographic image forming apparatus, wherein the presence or absence of the attachment of the developing device is detected based on the presence or absence of an input within the predetermined gate period. 2. The electrophotographic image forming apparatus is idling, the power is turned on, and at least the maintenance of the developing device is performed.
2. The developing device mounting detection device in an electrophotographic image forming apparatus according to claim 1, wherein the presence or absence of mounting of the developing device is detected when a cover that is opened and closed during inspection is closed. 3. During the image forming operation of the electrophotographic image forming apparatus, density detection based on counting the number of pulses generated within the predetermined gate period is repeatedly performed for toner replenishment control, and the density for toner replenishment control is controlled. 2. The developing device mounting detection device in an electrophotographic image forming apparatus according to claim 1, wherein when the pulse signal is not continuously input a predetermined number of times or more in the detection, it is determined that the developing device is missing.