JPH0717079Y2 - Remaining developer detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a printer to which an electrophotographic technique is applied, and more particularly, to a developing apparatus used in these image forming apparatuses. The present invention relates to a residual developing amount detection device.

[Prior art]

If the developer in the developing device used in an electrophotographic copying machine or a printer to which the electrophotographic technology is applied is insufficient, the print density decreases. Therefore, a sensor for detecting the developer is provided in the developing device and the sensor output is used. There is a device configured to control the developing and forming operation. For example, when the remaining amount of developer is reduced to a predetermined amount, the sensor detects this and
There is a system that uses this detection signal to give advance notice that the developer is exhausted.

In such a case, after giving a notice, set the position of the sensor so that it is possible to print on approximately 100 sheets of paper,
If the toner is not replenished after the notice, the image forming operation of the apparatus is controlled to automatically stop when the number of printed sheets reaches 100 after the notice.

[Problems of conventional technology]

In the image forming apparatus in which the control operation is performed as described above, a sensor such as an electrostrictive oscillator that detects the presence or absence of the developer is used as the developer detection sensor.
Since it is a flowable fine powder, and the amount of developer consumed by one image forming operation is very small, the developer on the sensor changes from the state with the developer to the state without the developer at a certain point. Can never change. For this reason, when the developer in the developing device becomes deficient, the sensor irregularly outputs a signal with and without a signal of the developer, and at what time it is determined that the developer is not present. It was difficult. Therefore, in the past, when the sensor first generated a no-developer signal, it gives a notice of no-developer, and thereafter,
When the predetermined number of printing operations were counted, the device was controlled to stop, but as described above, the timing at which the sensor first generates the no developer signal tends to be irregular depending on the biased state of the developer, etc. If the timing of the stop time of the apparatus is started from the first generation of the no developer signal, the image forming operation of the apparatus may be stopped before the developer is completely consumed, which is not preferable.

[Purpose of device]

In view of the above-mentioned conventional drawbacks, the present invention can surely determine the developer deficiency state in the developing device, and can stop the image forming operation of the device when the developer is completely consumed. An object is to provide a developer residual amount detection device.

[Key points of device]

In order to achieve the above object, the present invention provides a developing device for developing an electrostatic latent image on an image bearing member, and a developer remaining amount detecting device equipped with a detecting element for detecting the presence or absence of a developer in the developing device. , A first counter for accumulating the number of image forming operations while the detection element continuously detects the developer presence state, and a number of image forming operations while the detection element detects the absence of developer state. In addition to the integration, even if the detection element detects the developer presence state, it is not reset unless the first counter counts a predetermined number, and continues to accumulate the number of image forming operations while detecting the developer absence state. A second counter and a control circuit for stopping the image forming operation when the count value of the second counter exceeds a limited number are provided.

[Example of device]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a main part configuration diagram showing a part of the internal structure of the liquid crystal printer according to the present invention.

In FIG. 2, reference numeral 1 is a photosensitive drum having a photoconductive thin film formed on its peripheral surface, and is adapted to rotate at a constant speed in the illustrated direction. In the image forming operation of the photosensitive drum 1, first, the photosensitive drum 1 is charged by the charger 2, and thereafter, optical writing is performed by the print head 3 using a liquid crystal optical shutter or the like to electrostatically charge the surface of the photosensitive drum 1. A latent image is formed. This electrostatic latent image is developed with toner by the developing device 4, and a toner image is formed on the surface of the photosensitive drum 1. In this case, the toner a is agitated by the agitating rod 4 a, frictionally charged, and supplied to the surface of the photosensitive drum 1 by the developing roller 5. Further, a sensor 6 for detecting toner such as an electrostrictive vibrator is fixed to the lower end of the developing device 4,
A toner-absent signal indicating that the toner a therein is exhausted is sent to a control unit described later. When the sensor 6 detects that there is no toner, the control unit displays an indication that toner is to be supplied to the developing device 4. When the toner is not replenished after the toner replenishment is displayed, a part of the toner a remains on the developing roll 5 side. Therefore, as will be described later, the sensor 6 detects no toner. It is possible to print about 100 sheets, and the image forming operation is automatically stopped after printing about 100 sheets. After the development, the toner image formed on the photosensitive drum 1 is transferred by the transfer device 7 to the paper T fed from the paper feed cassette 14 through the paper feed roller 15 and the standby roll 9, and thereafter, The paper T is subjected to a fixing process in the fixing device 11, and then the paper discharge roll 12
Is discharged to the outside of the machine. A paper discharge sensor 13 for monitoring passage of the paper T discharged onto the paper conveyance path immediately before the paper discharge roll 12
Is provided, and the signal output from the paper discharge sensor 13 is sent to the CPU (central processing unit) of the control unit described later.

On the other hand, a part of the untransferred toner remains on the surface of the photosensitive drum 1 after the transfer, and this residual toner is removed by the cleaning device 8.
It is removed by the inner blade 8a.

Next, the control unit of the liquid crystal cleaner will be described with reference to FIG.

In FIG. 1, 16 is a CP that controls the operation of the liquid crystal printer.
U, program counter PC, stack S registers A and B, register X, flag F, arithmetic logic unit
Has ALU etc. The ROM 17 is a fixed memory that stores a control program and data for controlling the operation of the CPU 16, and the RAM 18 is a memory used for various controls such as counting the number of printed sheets.
The EE-PORM 19 is a non-volatile memory that can electrically erase and write data, and stores data such as the number of printed sheets. These memory and CPU16
Are connected by the address bus 21 via the address decoder 20 and are decoded by the address decoder 20 when the CPU 16 accesses each memory. The CPU 16 and each memory are connected by a data bus 22. By exchanging data via the data bus 22, various processes such as counting the number of printed sheets are executed. Furthermore, CPU16
Output latch 2 via address bus 21 and data bus 22
Connected to 3, 24 and input buffers 25, 26. The output signal of the output latch 23 is sent to a display device 27 using a 7-segment display element, and a toner-free display of the developing device 4 and various displays of the set number of prints are displayed according to a command from the CPU 16. The output of the output latch 24 is sent to the load 28. The load 28 is, for example, a driving device that drives the photosensitive drum 1 that executes an electrophotographic process, an exposure lamp, a fixing heater, and the like. These loads are controlled based on the command. On the other hand, the sensor unit 29 includes, for example, the sensor 6 for detecting the toner in the developing device 4 and the paper T.
It is composed of a paper discharge sensor 13 for detecting the discharge of paper, and the output signals of these sensors are input to the CPU 16 via the input buffer 25. The CPU 16 performs various controls such as image forming process control and toner replenishment display based on the outputs of these sensors. The input unit 30 is composed of a keyboard provided on an operation panel (not shown), and the number of printed sheets and the like are set by the input unit 30. The output of the input section 30 is the input buffer 26.
The CPU 16 performs control based on the instruction set by the input unit 30 via.

The paper discharge sensor 13 and the sensor 6 for detecting toner included in the sensor unit 29 are specifically as shown in FIG.
A photo sensor 13, a sensor 6 including an electrostrictive oscillator for detection, and peripheral circuits of these sensors.
The output of the light receiving element (phototransistor) 13b of the paper discharge sensor 13 using the photo sensor is input to the terminal of iN1 of the CPU 16 via the Schmitt gate 31, and when the paper is not in the paper discharge sensor 13, Light emitting element (light emitting diode) 13
Since the light of a is received by the light receiving element 13b, the light receiving element 13b is turned on and a high level signal is output from the Schmitt gate 31.
Input to CPU16. Further, while the paper T is passing through the paper discharge sensor 13, the light receiving element 13b is turned off, so that a low level signal is input to the CPU 16. On the other hand, the output of the sensor 6 that detects the toner in the developing device 4 is input to the toner detection circuit 32. When the sensor 6 detects the absence of toner, it outputs an AC signal, which turns on the transistor Q of the toner detection circuit 32, so that a low level signal is output to the iN2 terminal of the CPU 16 as a toner-less signal. Is entered. When the sensor 6 detects that toner is present,
Since the output operation of the AC signal is stopped, the transistor Q is turned off, which outputs a high level signal to the CPU 16.

Fig. 4 shows the address map of CPU16, RAM18
For addresses 0000-0800, EE-PROM19 for addresses 4000-
Located at 4800. In addition, I / O addresses 8000-8020
The ROM 17 is located at the addresses C000 to FFFF, and the other addresses are unused.

EE-PROM19, as shown in FIG.
It is divided into 256, and the area of 1 unit is TOTLCNT, TONC
It has data storage areas designated as NT1, TONCNT2, CNT1UP, CNT2UP. TOTLCNT (total counter) stores the total number of prints of the liquid crystal printer, and consists of 3 bytes. Also, TONCNT1 (toner counter 1)
As will be described in detail later, is for storing the number-of-printed-sheet data after the sensor 6 detects the presence of toner, and is composed of 2 bytes. TONCNT2 (toner counter 2) is
The sensor 6 stores data on the number of printed sheets after detecting the absence of toner. When the number of printed sheets reaches 100, the image forming operation is stopped. CNT1UP
And CNT2UP are areas in which flags for controlling whether to perform the counting operation of TONCNT1 and TONCNT2 are set. The EE-PROM19 has a storage area for 5 types of data such as TOTLCNT in a unit area consisting of 8 bytes, but the number of rewriting of the EE-PROM19 is currently limited to about 10,000 times. . On the other hand, the number of durable prints of the liquid crystal printer of this embodiment is abnormal at 300,000 sheets, and the count data is recorded in the EE-PROM for each printing operation.
When rewriting to 19, it is necessary to rewrite 300,000 times. Therefore, the entire storage area of the EE-PROM 19 is divided into 256 areas, and this storage area is sequentially shifted for each print operation, thus rewriting 2.56 million times in total,
That is, up to 2.56 million sheets can be counted.

Figure 6 shows the address map of RAM18, ADDRM
EM (address memory), AREANCT (area counter), E
There is an area shown as EPCTW (count write of EE-PROM), and these are used auxiliary as a temporary storage means when counting the number of printed sheets of the liquid crystal printer, as described later. Also, TMPREG (temporary register) 1
The same applies to ~ 5, and further TOTLCNT, TONCNT1, TONCNT2, C
NT1UP and CNT2UP correspond to the data with the same symbol in the EE-PROM 19 described above, and the actual counter operation is performed using this counter area.

Next, the operation of the above embodiment will be described. First, the overall operation of the liquid crystal printer will be described with reference to the flowchart shown in FIG.

In step (hereinafter referred to as ST) 1, when the power of the apparatus is turned on, a process of initializing the liquid crystal printer is performed. For example, the heater for fixing is turned on or the wire is checked for disconnection, the thermistor in the fixing unit is checked for wire disconnection, and the print head is ready for checking. Next, in ST2, AREACHK (area check) is performed, and each counter data stored in each storage area of the EE-PROM 19 is transferred to the RAM 18. In ST3,
A sensor 6 for detecting the toner, as indicated by TONRCHK.
The remaining toner amount in the developing device 4 is checked based on the output of After this, it is determined whether or not TONCNT2 has counted up, and if it has not counted up, the process proceeds to ST7. The TONRCNT2 counts the number of printed sheets after the toner detection sensor 6 detects the absence of toner, and counts up when 100 sheets are counted. Therefore, if the count is not up in ST4, printing can be performed until the number of sheets reaches 100. On the other hand, if the count is up in ST4, it is determined in ST5 whether or not the sensor 6 detects the absence of toner. In step ST7, if there is no toner, in step ST6 the image forming operation of the liquid crystal printer is forcibly stopped. In ST7, the count of each counter is performed as indicated by DTCNT, and each count value is written in the RAM 18 as described later. Then ST8
The EEPWRT process is executed in step S6. This process is a process of transferring each count data written in the RAM 18 to the EE-PROM 19, which will be described later in detail. After this process, ST
At 9, the normal processing of the printer is performed. When the process of ST9 is completed, the process returns to ST3 again, and the same operation is performed once for each printing operation.

Detailed processing of AREACHK in ST2 shown in FIG. 7 will be described with reference to the flowchart shown in FIG. The AREAC HK is a process of transferring the count data stored in the EE-PROM 19 up to full opening to each count area of the RAM 18 when the power is turned on. In addition, this process is EE-PR
Work to search the area where the count data (hereinafter referred to as the current count value) written last in OM19 is stored (ST1 to ST3), and work to transfer each data of the searched EE-PROM19 area to RAM18 (ST10 to ST12) consists of setting the address of the EE-PROM 19 to write the new data counted up (ST8 to ST9).

In detail, first, in ST1, set the top address of EE-PROM 19 to R
Write to ADDRMEM of AM18 and X register of CPU16, then
The value obtained by subtracting 1 from the total number of areas in EE-PROM19 (that is, 255) is R
Write to AREACNT of AM18. Next, the TOTLCNT data (area 1) stored in the area of the EE-PROM 19 addressed by the value stored in the ADDRMEM of ST2 is read, and TMPREG
Temporarily store to 1, 2, and 3. Then, the contents of the X register of the CPU 16 are incremented by 8 to specify the next area of the EE-PROM 19. After this, in ST3, the data of TOTLCNT in the next area 2 is CP
Read to A register of U16, and use this data and TMPR in ST2.
Compare the data stored in EG1, 2, and 3 (TOTLCNT data in area 1). At this time, if the TOTLCNT datum in area 1 is large, the data in area 1 is determined to be the current count value, and the process proceeds to FOUNDE (ST9). On the other hand, T in area 2
If the OTLCNT data is large, the work of comparing the TOTLCNT data of the area 2 with the TOTLCNT data of the next area 3 is performed. ST2 to ST7 form a loop, which compares the data in areas 2 and 3 and, if the data in area 3 is large, further compares the data in areas 3 and 4. Area n
And TOTLCNT data in area n + 1 is compared to TOT in area n
Repeat until the LCNT data becomes large, and EE-PROM19
Search for the address of the area that stores the current value (maximum value) of the print quantity data (TOTLCNT) stored in. Specifically, in ST5, 1 is subtracted from the AREACNT value, and in ST6 it is determined whether the value is 0. If the AREACNT value is not 0, ST7
Then, the method of writing the contents of the X register to ADDRMEM and returning to ST2 is used. As a result of repeating this process, AREA
When the value of CNT becomes 0, the top address (4000) of EE-PROM 19 is written to ADDRMEM at ST8, and the value obtained by subtracting 1 from the total number of areas is written to AREACNT. In this case, the area where the new count data should be written next is area 1 and the operation proceeds to ST10. That is, TOTLCNT in areas n and n + 1
By sequentially comparing the data, finally comparing the area 255 and the final area 256, and when the TOTLCNT data of the area 256 is larger, the value of the area 256 becomes the current value.

On the other hand, if Y in ST4, proceed to ST9, but here ADDRMEM
Save the contents of STACK to STACK of CPU16, write the current value of X register to ADDRMEM, restore the contents of STACK to X register, etc., then write the new count data to EE-PROM19 address Prepare for. Address m
Is the address of the area storing the current value, the address m + 8 is this address. The current count value retrieved in this way is stored in RAM18 in ST10 to ST12.
Will be transferred to the count area. That is, in ST10, the value of the X register (that is, the address of the EE-PROM 19 in which the current count value is stored) is stored in TMPREG1, 2, the TOTLCNT address of RAM18 is stored in TMPREG3, 4, and the number of moved bytes “8” is set to B. Set it in a register and prepare for transfer.
Proceed to. In ST11, the contents of EE-PROM19 addressed by the contents of TMPREG1, 2 are loaded into the A register, the contents of this A register are stored in the RAM 18 at the addresses addressed by TMPREG3, 4, the contents of TMPREG1, 2 and TMPREG3, A process of adding 1 to the contents of 4 and subtracting 1 from the contents of the B register is performed. After that, in ST12, it is determined whether or not the B register is 0. If it is 0, the process is ended. In this way, TOTLCNT, TONCNT1, TONCNT in the current count value storage area of EE-PROM19 are
2. The data of CNT1UP and CNT2UP are transferred to the respective counter areas of RAM18 marked with the same symbol, and the printer waits for calculation of the number of printed sheets when the liquid crystal printer is powered on.

Next, the operation of TONRCHK will be described with reference to the flowchart shown in FIG.

First, in ST1, the sensor 6 outputs to determine whether toner is present in the developing device 4. When it is determined in ST1 that toner is present, it is determined in ST2 whether the value of the toner counter TONCNT1 that counts the duration of the toner present state exceeds 20 counts. If the value of TONCNT1 exceeds 20 counts, the value of toner counter TONCNT2 is reset to zero in ST3, and the process proceeds to ST4. If the value of TONCNT1 is 20 counts or less, proceed directly to ST4. In ST4, the flag CNT1UP flag for performing the counting operation of TONCNT1 is set in RAM18, and ST5
The CNT2UP flag is reset to stop the counting operation of TONCNT2. Then, in ST6, the toner-free warning display is reset. On the other hand, if the absence of toner is detected in ST1, the CNT2UP flag is set in ST7 and the CNT1UP flag is reset in ST8. As a result, the operation of TONCNT1 that counts the toner present state period is stopped and the toner counter TONCN is
Allows T2 operation. Then, in ST9, the value of TONCNT1 is reset to zero. Then in ST10, determine whether the value of TONCNT2 exceeds 20 counts, and if it exceeds,
In ST11, the display process of the toner out warning is executed.

Next, the operation of the DTCNT shown in FIG. 7 will be described with reference to the flow chart shown in FIG. DTNC
T is a process of counting up the value of each counter based on the flag set by the flow of TONRCHK shown in FIG.

In FIG. 10, first in ST1, it is determined whether or not the paper discharge sensor 13 provided at the paper discharge port of the liquid crystal printer has operated. The paper ejection sensor 13 is turned on every time printing of one sheet of paper is completed.
This is a sensor that is turned off. When the paper discharge sensor 13 operates, it is detected that the printing operation for one sheet has been completed. When the operation of the paper discharge sensor 13 is confirmed in ST1, it is determined in ST2 whether or not the count-up instruction flag CNT1UP of the counter TONCNT1 that counts the duration of the toner present state is set, and if it is set, ST3 The TONCNT1 value is incremented by +1. Next, in ST4, the count-up instruction flag C of the counter TONCNT2 that integrates the number of image forming operations while the sensor 6 detects the absence of developer state
It is determined whether or not NT2UP is set, and if it is set, the value of TONCNT2 is incremented by 1 in ST5.
Next, in ST6, the value of the total counter TOTLCNT is also incremented by +1 and these count data are written to the EE-PROM 19, so in ST7, the numeral 8 is set in the EEPCTW area of the RAM 18.

Next, the operation of the EEPWRT described in FIG.
Description will be given with reference to the drawings. This EEPWRT is RAM18
This is the process of writing the count data EE-PROM19 stored in the memory.

In FIG. 11, in the EEPCTW of the RAM 18, as described above, a numerical value 8 indicating a write request to the EE-PROM 19 when one printing operation is completed.
Is set. Therefore, the contents of EEPCTW are checked (ST1), and when 8 is written, it is determined that there is a write request, and the process proceeds to ST2. On the other hand, if it is 0, it is determined that there is no write request, and data writing to the EE-PROM 19 is not performed. In ST2, it takes about 10 to 20ms to write 1 byte of data due to the performance of EE-PROM19. Is a timer running to delay the write operation after writing 1 byte of data? Determine whether or not. Therefore,
When the timer is not running, write the number of prints to EE-PROM19 in ST3. This write is a 1-byte data write, and the value obtained by subtracting 1 from the contents of EEPCTW is set in the B register, the contents of ADDRMEM are loaded into the X register, the X register and the B register are added, and the EE-PROM is written.
Find the store destination address of 19 and save it on the stack, RAM18
The TOTLCNT address of is added to the value of the B register to obtain the load side address of RAM18, and the data in this address is A
It is written by loading the register and writing the contents of the A register to the address of the EE-PROM 19 designated by the data in the stack. ST4 and 5 are for saving the time to sequentially write the data of each byte as described above.

In ST6, 1 is subtracted from the contents of EEPCTW every time 1-byte data is written, and then it is determined in ST7 whether the contents of EEPCTW are 0 or not. At this time, if 0 (ST7 is Y), AREACNT
1 is subtracted from the content of (ST8), and then it is determined whether the content of the AREACNT is 0 (ST9). If the content of AREACNT is not 0 (N in ST9), the content is rewritten by adding 8 to ADDRMEM so as to designate the next write address in ST10. On the other hand, if the content of AREACNT is 0 (ST9 is Y), it means that the data has been written in area 256, so in ST11, EE-PROM19.
Store the top address in ADDRMEM, store the value obtained by subtracting 1 from the total number of areas in AREANCT, and set ADDRMEM and AREANCT to write from area 1 again.

In the example, TOTLCNT, TONCNT1, TONCNT2, CNT1U
The five contents of P and CNT2UP are shown. Regarding the search of the area where the current count value of EE-PROM19 is stored,
Only TOTLCNT data is compared. That is, the other 4
Data is ancillary to TOTLCNT, so TOTLC
The value of NT is managed as a representative of the current value. Furthermore, EE
-When writing to PROM19, the TOTLCNT data is written last, and the data of TOTLCNT consists of 3 bytes, but the lowest byte is written. This is to prepare for power-off for data writing. For example, if the power is cut off before writing all 8-byte count data to the EE-PROM 19, the EE will be returned at the next power-on.
-The count data stored in the area immediately before the last written area of PROM 19 becomes the current value, and in any case, the error is one and the error is minimized.

[Effect of device]

As described above in detail, according to the toner remaining amount detecting device of the present invention, the counter TONC which integrates the number of image forming operations while the sensor 6 continuously detects the presence of the developer.
The counter TONCNT2 has an NT1 and a counter TONCNT2 that counts the number of image forming operations during which the sensor 6 detects the absence of the developer. Counter TO, even if detected
Unless NCNT1 counts a predetermined number, it is not reset, and since the sensor 6 continues to accumulate the number of image forming operations while detecting the absence of developer, the stop time of the device is controlled based on the count of this cow TONCNT2. By doing so, it becomes possible to stop the image forming operation of the printer exactly after a lapse of a predetermined period after the toner amount in the developing device becomes insufficient.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a liquid crystal printer according to the present invention, FIG. 3 is a circuit diagram showing a concrete example of a sensor unit, and FIG. 4 is a CPU. 5 is an explanatory view showing an address map of the EE-PROM, FIG. 6 is an explanatory view showing an address map of the RAM, and FIG. 7 is a flowchart showing the entire operation of the liquid crystal printer. 8 is a flowchart showing the operation of AREACHK, FIG. 9 is a flowchart showing the operation of TONRCHK, FIG. 10 is a flowchart showing the operation of DTCNT, and FIG. 11 is a flowchart showing the operation of EEPWRT. 1 ... Photosensitive drum, 3 ... Print head, 4 ... Developing device, 6 ... Sensor, 13 ... Paper ejection sensor, 16 ... CPU, 18
... RAM, 19 ... EE-PROM.

Claims (1)

[Scope of utility model registration request] 1. A developing device for developing an electrostatic latent image on an image carrier, and a developer remaining amount detecting device comprising a detecting device for detecting the presence or absence of a developer in the developing device, wherein the detecting device is a developing device. A first counter that integrates the number of image forming operations while continuously detecting the developer presence state, and an integration of the number of image forming operations while the detection element is detecting the absence of developer state and the detection A second counter that continues to accumulate the number of image forming operations during the period when the element detects a developer present state and is not reset unless the first counter counts a predetermined number, and the developer is absent, A developer remaining amount detecting device comprising a control circuit for stopping an image forming operation when the count value of the second counter exceeds a limited number.