JPH10142910A - Toner supplying system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To self-diagnose erroneous detection in the case of the erroneous detection of a toner detecting sensor so as to take an appropriate countermeasure. SOLUTION: In this system by which developer 29 is stirred to circulate, toner concentration is detected by a toner concentration sensor 49 provided inside a developing device 8, toner is supplied inside the device 8 from a toner storing part in the case the value of the toner concentration of the developer 29 is below a previously specified value, and the toner is supplied from a toner cartridge in the case the detecting sensor 50 provided in the toner storing part detects that the toner amount inside the toner storing part is below a specified amount; when the sensor 49 consecutively detects that the toner concentration inside the device 8 is below a specified value for a specified time or more and the sensor 50 in the toner storing part never detects non-existence of the toner while the value of the toner concentration is detected to be below the specified value, the sensor 50 is decided not to accurately work, and the error display is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply system for an image forming apparatus such as a copying machine and a laser beam printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a laser beam printer, a photosensitive drum is charged uniformly by a corona charger, and image data is projected on the photosensitive drum by an optical projection device to form a latent image. Then, the latent image is developed by a developing device to form a toner image. The developer used in this developing device is composed of a toner (colored powder) and a carrier (fine iron powder), and the toner and the carrier are well stirred and screwed by a screw as a stirring / circulating means provided in the developing device. It is mixed and moves in the direction of the magnetic brush, and adheres to the surface of the magnetic brush by the magnetic force of the magnetic brush. The latent image on the photosensitive drum is developed by the magnetic brush to form a toner image. To replenish the toner consumed by such image formation into the developing device,
It is necessary to appropriately supply toner for replenishment with a toner cartridge, a toner hopper, or the like, and to quickly and sufficiently agitate and circulate the supplied toner together with the carrier in the developing device to prepare for the next image formation.

As an example of a system for supplying toner into a developing device, a toner cartridge having a first supply unit and a toner storage unit having a second supply unit for temporarily storing replenishment toner supplied from the toner cartridge are provided. Is known. In this case, a toner concentration sensor provided in the developing device detects the toner concentration of the developer,
A supply signal is output when the toner density falls below a certain value. The toner density sensor changes an analog output voltage according to a change in the toner density, and detects the toner density by using the change in the analog output voltage. The second supply means such as a supply screw is operated from the toner storage section based on the supply signal, and the toner in the toner storage section is supplied into the developing device. Further, the amount of toner in the toner storage unit is detected by a toner detection sensor provided in the toner storage unit.
Supplies supply toner to the toner storage section. By providing the toner storage section for temporarily storing the toner for supply, the toner supply into the developing device becomes quantitative, and the toner concentration in the developing device can be accurately controlled.

Normally, carrier 95% by weight / toner 5%
When the developer (standard developer) is mixed at a weight ratio (toner density is 5%), the analog voltage output from the toner density sensor is about 2.5 V (threshold voltage Vth)
The circuit has been adjusted so that Now, when the toner concentration of the developer is lower than the standard developer (toner concentration is 5%) and the toner concentration is 4% (toner concentration is reduced by 1%), an analog signal output from the toner concentration sensor is output. The voltage is about 0.4 V higher than the threshold voltage Vth (about 2.5 V). When the toner concentration of the developer becomes higher than the standard developer (toner concentration is 5%) and the toner concentration becomes 6% (toner concentration is increased by 1%), the analog signal outputted from the toner concentration sensor is output. The voltage is about 0.4 V lower than the threshold voltage Vth (about 2.5 V). The signal output from the toner density sensor is based on an analog voltage detected based on the toner density, and the analog output voltage is a threshold voltage Vth (about 2.5 V).
V) or higher, and when the analog output voltage is lower than the threshold voltage Vth (about 2.5 V), Hig
It is output as a digital signal indicating the h level. The toner has a digital output (H) output from the toner density sensor.
(high level), the toner and the carrier are supplied from the toner reservoir to the screw side for stirring and mixing the toner and the carrier.

To supply the toner from the toner reservoir to the screw side in the developing device, the toner supply screw which is stopped when the toner is not supplied is rotated by turning on the toner supply clutch. . This toner supply clutch is used for 0.5 seconds per toner supply.
When the toner supply clutch is turned ON for about 1.0 second per one toner supply, the amount of toner supply when the toner supply clutch is ON is about 3.5 g (corresponding to about 0.07% in toner density). The supply amount is about 7.0 g (about 0.1 g in toner concentration).
14%).

Since the toner concentration sensor is provided at the center in the longitudinal direction of the cylindrical developing device, even if the toner is supplied from the toner storage section to the developing device, the toner concentration to which the toner has been supplied is immediately detected. Not necessarily
The correct toner concentration can be detected only after the toner is stirred and mixed with the carrier and conveyed to the position of the toner concentration sensor in the developing device. It takes 19 seconds for the removed toner to move to the position of the toner density sensor in the developing device.

Once a toner supply command is issued by the toner concentration sensor and toner is supplied from the toner storage unit into the developing device, the toner supply is performed for about 7 seconds per one second of toner supply.
g of toner is supplied and the toner concentration increases by 0.14%. Therefore, when the digital output of the toner density sensor is at the LOW level, if the toner is always supplied without taking an interval, when printing the A0 size, (7.0 g / sec) × (19 sec) = 133 g
Will also be supplied. Then, the toner density is increased by 3.0% from before the toner supply. Therefore, when such a control is actually performed, the initially supplied developer having a 5% toner concentration has an 8% toner concentration after copying about 5000 m. As a result, only a print image with a lot of fog and an over-developed image can be obtained. Therefore, it is necessary to regulate the toner supply amount per unit time. One way to regulate the amount of toner supply per unit of time is to reduce the toner supply capacity. However, if it is reduced too much, it will be possible to respond to continuous printing with a high printing rate (toner consumption). Will be gone.

Further, in order to shorten the response time required for correctly detecting the toner concentration after the toner is supplied,
There is also a method of arranging a toner density sensor near the toner supply port, but the newly replenished toner reaches the toner density sensor section before it is mixed sufficiently stably, and as a result, the toner density sensor Is incorrectly determined, and correct toner density control cannot be performed.

Further, in order to minimize the ripple in the toner density control, it is necessary to regulate the toner supply amount per unit time as small as possible. The minimum necessary toner supply amount per unit time differs depending on the size of the printing paper.

The toner supply system for supplying the toner to the screw side for stirring and mixing the toner and the carrier is as shown in Table 1 in a conventional developing device such as a copying machine or a laser beam printer. . Table 1 That is, in the toner supply system in the developing device shown in Table 1, the period (toner supply step) T1 for actually supplying the toner differs depending on the size of the printing paper.

In the case of A0 size print paper, when the developing device is on standby, the toner density is detected after a sec (for example, 10 sec), and the toner density is lower than the standard density (toner density is 5%) (toner density sensor). When the signal output from the controller is Low, the screw for stirring and mixing the toner and the carrier is placed on the screw side for a predetermined time (for example, 0.5).
Second) Toner is supplied from the toner storage unit. When the toner is supplied, the toner is not supplied regardless of the toner concentration (for 10 seconds, regardless of the toner concentration (the state of the toner concentration is not read).
After sec), the toner density is detected. If the toner density is lower than the standard density (toner density is 5%) (the signal output from the toner density sensor is low), the same operation is performed. After a sec (for example, 10 sec), the toner density is detected, and the toner density is set to the standard density (the toner density is set to 5
%) (The signal output from the toner density sensor is High), the toner is not supplied, and monitoring is performed until the output from the toner density sensor becomes Low, and the output from the toner density sensor becomes Low. At this point, the toner is supplied from the toner reservoir to the screw side for stirring and mixing the toner and the carrier for a predetermined time (for example, 0.5 seconds), and a
During the sec (for example, 10 sec), the toner supply is not performed regardless of the toner density (the state of the toner density cannot be read).

In the case of A1 size print paper, the time from the supply of toner to the detection of the next toner concentration is 1.4ase.
c (for example, 14 sec), and in the case of A2 size print paper, the time from the supply of toner to the detection of the next toner concentration is 2 asec (for example, 20 sec).
In the case of three-size print paper, the time from the supply of the toner to the detection of the next toner concentration is 2.8 asec (for example, 2 seconds).
The toner supply cycle is different, for example, to 8 seconds. Note that the toner supply here does not mean supplying the toner from the toner cartridge to the developing device, but supplying the toner stored in the toner storage portion of the developing device to the screw side for stirring and mixing the toner and the carrier. is there.

When the toner stored in the toner storage portion of the developing device is exhausted, the toner detection sensor detects that there is no toner, and each time, the motor for replenishing the toner from the toner cartridge is rotated. The state where the toner has accumulated in the portion is maintained. When the toner detection sensor detects the absence of toner continuously for several tens of seconds, for example, for 60 seconds, a toner absence detection display is displayed. T1 in Table 1
Seconds later, the digital output of the toner density sensor is still L
When it is at the low level, the toner is supplied again for a predetermined time (for example, 0.5 seconds), and no toner is supplied during the subsequent T1 seconds regardless of the digital output value of the toner density sensor. . By repeating this, the toner density is controlled. However, if the machine has not been operated for a long period of 30 minutes or more, the bulk density of the developer is unstable, and the first few seconds (for example, regardless of the digital output value of the toner density sensor) (One second), no toner is supplied. Similarly, when the power of the fixing device is turned on when the temperature of the fixing device is 50 ° C. or less, for example, in the morning, the developing device is considered to be left for a longer time, and for the first several tens of seconds (for example, 30 seconds) ( During the period in which the developing device is operated for 30 seconds, toner is not supplied regardless of the digital output value of the toner density.

On the other hand, another example of the developing device is a developing device provided with a toner hopper having a toner supply means. The remaining amount of toner in the developing device is detected by a toner detection sensor, and the remaining toner amount is determined in advance. 2. Description of the Related Art A developing device that supplies toner from a toner hopper when a value falls below a predetermined value is known.

[0015]

SUMMARY OF THE INVENTION Toner detection sensors include:
If a small amount of toner is attached or the connector of the toner detection sensor is disconnected, the toner may not be supplied properly or the absence of toner may not be detected even though there is no remaining toner. When this abnormality occurs, there is a possibility that the toner concentration is extremely reduced, and eventually, the carrier adheres to the photosensitive drum and the drum is damaged. In the conventional toner supply method, even if a small amount of toner is stuck to the toner detection sensor or the connector of the toner detection sensor is disconnected, it is possible to take measures against erroneous detection that no toner is detected. could not. In addition, when prints with a high printing rate (toner consumption) are continuously performed, the toner density may be extremely reduced, the carrier may adhere to the photosensitive drum, and the drum may be damaged. In the conventional toner supply method,
When printing with a large printing rate (toner consumption) continues continuously, the supply of toner may not catch up.

A first object of the present invention is to make a self-diagnosis of an erroneous detection when a toner detection sensor detects an erroneous detection and to take an appropriate measure. A second object of the present invention is to make it possible to catch up with the supply of toner even when printing with a large printing rate (toner consumption) continues continuously.

[0017]

According to a first aspect of the present invention, there is provided a toner supply system including a toner storage unit for temporarily storing toner supplied by a toner cartridge. The developer comprising the toner and the carrier is stirred and circulated by a stirring / circulating means provided in the developing device, and the toner concentration of the developer is detected by a toner concentration sensor provided in the developing device, and the toner concentration of the developer is determined in advance. When the value falls below the value, the toner is supplied from the toner reservoir to the developing device, and the amount of toner in the toner reservoir is detected by a toner detection sensor provided in the toner reservoir.
In a toner supply system for supplying toner from a toner cartridge when the amount of toner in the toner reservoir falls below a certain amount, the toner concentration sensor continuously detects that the toner concentration in the developing device falls below a certain value for a predetermined time or more. If the toner detection sensor of the toner storage unit does not detect the absence of toner at all while detecting and detecting the toner concentration below the predetermined value, the toner detection sensor is operating correctly. It is determined that there is no error, and an error is displayed. With this configuration, when an erroneous detection is detected by the toner detection sensor,
The self-diagnosis of the erroneous detection can be performed so that an appropriate action can be taken.

According to a second aspect of the present invention, in the toner supply method, the printing operation is stopped simultaneously with or before or after the error display. With this configuration, when an erroneous detection is detected by the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

According to a third aspect of the present invention, there is provided a toner supply system wherein a time during which the toner density in the developing device is lower than a predetermined value is integrated by a backup means. With this configuration, when an erroneous detection is detected by the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

According to a fourth aspect of the present invention, there is provided a toner supply system including a toner storage section for temporarily storing toner supplied by a toner cartridge, wherein a stirring / circulating portion provided in the development apparatus is provided. The developer composed of toner and carrier is stirred and circulated by the means, and the toner concentration of the developer is detected by a toner concentration sensor provided in the developing device, and when the toner concentration of the developer falls below a predetermined value, The toner is supplied from the toner storage unit into the developing device, and the amount of toner in the toner storage unit is detected by a toner detection sensor provided in the toner storage unit. When the amount of toner in the toner storage unit falls below a certain amount, the toner is supplied from the toner cartridge. The toner density sensor continuously detects that the toner density in the developing device falls below a certain value. And the toner detection sensor of the toner storage unit detects the absence of toner at least once during the detection of the toner concentration below the certain value for a predetermined time or more, and the printing with a high printing rate is performed. Is determined, and the toner supply amount per unit time is changed. With this configuration, even when printing with a high printing rate (toner consumption) continues continuously, the supply of toner can be caught up.

According to a fifth aspect of the invention, in the toner supply method, the change of the toner supply amount per unit time is such that the toner supply timing is shorter than the current toner supply cycle. With this configuration, even when printing with a high printing rate (toner consumption) continues continuously, the supply of toner can be caught up.

According to a sixth aspect of the present invention, in the toner supply method according to the first aspect, after the toner supply amount is changed, when the toner density sensor detects that the predetermined value is exceeded at least once or more, Is returned to the state before the change. With this configuration, even when printing with a high printing rate (toner consumption) continues continuously, the supply of toner can be caught up.

According to a seventh aspect of the present invention, there is provided a toner supply system wherein the time during which the toner concentration in the developing device is lower than a predetermined value is integrated by a backup means. With this configuration, when an erroneous detection is detected by the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

In the toner supply system according to the present invention, the toner supplied by the toner hopper is agitated by an agitating means provided in the developing device, and the toner sensor provided in the developing device is consumed by image formation. Detecting the remaining amount of toner that has been discharged, and supplying the toner from the toner hopper when the remaining amount of toner is lower than a predetermined value. When the sensor continuously detects for a predetermined time or more, it is determined that printing with a high printing rate has been performed, and the toner supply amount per unit time is changed. Thereafter, the remaining amount of toner in the developing device is constant for a set time or more. When the toner sensor detects that the value exceeds the value, the toner supply amount per unit time is returned to the state before the change. With this configuration, even when printing with a high printing rate (toner consumption) continues continuously, the supply of toner can be caught up.

[0025]

Embodiments of the present invention will be described below. FIGS. 1 to 5 show an embodiment of a toner supply system when an abnormality is detected in a toner amount detection sensor according to the present invention. FIG. 1 is a side sectional view showing an example of an image forming apparatus to which a toner supply method is applied when an abnormality of a toner amount detection sensor is detected. The image forming apparatus 1 such as a copying machine and a printer is roughly composed of an image forming section 2, transfer material conveyance guide means 3, a fixing device 4, and a roll paper feeding section 9.

In the image forming section 2, a corona charger 6 for uniformly charging the surface of the photosensitive drum 5 around the photosensitive drum 5, and original data read by a scanner or the like are projected by an LED or the like, and the photosensitive drum is projected. An optical projection device 7 for forming a latent image on the developing device 5, a developing device 8 for developing the latent image, and a transfer of the developed toner image to a transfer material sent from a paper feeding unit 9 loaded with roll paper (or cut paper). Transfer corona discharger 10, an AC separation corona discharger 11 for separating a transfer material from the photosensitive drum 5, and a cleaning device 1 for removing toner remaining on the surface of the photosensitive drum 5 after transfer.
2. An eraser lamp 13 for uniformly removing the surface potential of the surface of the photosensitive drum 5 is provided, and these are arranged so as to sequentially act on the photosensitive drum 5, so that image formation is performed as is well known. Will be A toner supply port 19 is provided at one longitudinal end of the developing device 8 (side surface of the photosensitive drum in the axial direction).
Is provided, and the supply port 2 of the toner cartridge 20 is provided.
1 is covered with a guide member 22 so as not to scatter the toner into the apparatus at the time of supply, and is connected by being pressed around the mouth by a sponge 23 or the like.

FIG. 2 is a side sectional view of the developing device 8. In the figure, a casing 24 of the developing device 8 has an opening 25 facing a part of the surface of the photosensitive drum 5.
A developing roller 26 is provided so that a part of the peripheral surface is exposed from the opening 25 and is close to the photosensitive drum 5. Also,
A stirring / circulating unit 100 is provided for stirring and circulating the developer 29 stored in the developing device 8 and the supplied toner so as to be close to the developing roller 26. The stirring / circulating means 100 is rotated by a second
And the screw 37. 32 is a partition plate, 49 is a toner density sensor described later, and 50 is a toner detection sensor described later.

The developing roller 26 has a sleeve 27 formed in a cylindrical shape, and a sleeve 27 inside the sleeve 27.
And a plurality of permanent magnets 28 fixedly arranged separately from the sleeve 27 at appropriate places along the inner peripheral surface of the sleeve 27. The sleeve 27 moves outside the arranged permanent magnets 28 in a direction shown by an arrow C. It is designed to rotate. The developer 29 is attracted to the outer peripheral surface of the sleeve 27 of the developing roller 26 by the magnetic force of the permanent magnet 28 to form a magnetic brush 30. The thickness of the magnetic brush 30 is regulated by a regulating plate 31 provided in the vicinity of the opening 25 of the casing 24 of the developing device 8 so as to have a constant thickness. The toner is transferred and developed on the surface of the photosensitive drum 5 in contact with the surface.

FIG. 3 shows the internal structure of the casing 24 of the developing device 8. The casing 24 has two storage chambers 3 at the center in the width direction and a partition plate 32 in the longitudinal direction.
3, 34 are formed. At one end of the storage chamber 33, a toner supply port 35 for supplying toner into the storage chamber 33 is provided. The partition plate 32 has a casing 24.
A first communication path 32A that connects the storage chamber 33 and the storage chamber 34 is formed at an end opposite to the side where the toner supply port 35 is formed. Further, a second communication passage 32 </ b> B that connects the storage chamber 33 and the storage chamber 34 is formed at an end of the partition plate 32 on the side of the casing 24 where the toner supply port 35 is formed.

The stirring / circulating means 100 will be described in detail with reference to FIG. Inside the casing 24 of the developing device 8,
At least two screws for stirring the developer 29, in this example, a first screw 36 and a second screw 37 are provided close to the inner surface of the casing 24. First screw 36 and second screw 37
Has stirring blades 36B and 37B, respectively, and is rotated by a motor 38 in directions of arrows A and B as shown in FIG. By the action of the stirring blades 36B and 37B, the developer is transported in the directions of the arrow D and the arrow E, and the developer is passed through the communication paths 32A and 32B provided in the partition plate 32. The agent and the supplied toner are stirred and circulated.

Reference numeral 49 denotes a toner density sensor, which is provided on the side of the developing device 8.
This is for detecting the mixing ratio (density) of the toner and the carrier charged into the casing 24 of the developing device 8. In the present embodiment, the toner density sensor 49 is constituted by a magnetic sensor, detects the magnetic permeability of the developer 29, and detects the developer 2 in the storage chamber 33 based on the detected magnetic permeability.
9, the toner density is detected based on whether the voltage value detected by the toner density sensor 49 is higher or lower based on the output voltage at the time of the reference toner density. Reference numeral 50 denotes a toner detection sensor, which is located below the toner supply port 35 and formed in a space around the third screw 41 in the storage chamber 33.
This is for detecting whether or not the amount of the toner filled in 1 is equal to or more than a certain amount (there is no case where the amount is less than the certain amount). Then, the third screw 41 is driven to supply the toner from the toner storage section 51 to the storage chamber 33, and the toner detection sensor 50 detects that the toner amount has dropped below a certain amount, and the toner is stored in the toner cartridge 20. The toner reservoir 51 is filled with toner by a supply unit (not shown) provided.

When an image is formed by such a structure, the developer 29 composed of toner and carrier is used.
Is used, and the carrier remains in the storage chamber 34 without being used. The toner density sensor 49 detects the amount of toner consumed during image formation, that is, a change in the mixing ratio between toner and carrier. When the toner concentration in the developer 29 becomes lower than the predetermined value, the clutch 42 connected to the motor 38 is operated to rotate the third screw 41. The rotation of the third screw 41 conveys the toner in the toner storage section 51 to the tip of the first screw 36 by the conveyance action of the third screw 41. The toner conveyed to the distal end of the first screw 36 adds toner to the developer 29 having a reduced toner concentration sent through the second communication path 32B by the action of the first screw 36. Then, the mixture is stirred and mixed until it reaches the first communication passage 32A, and is further fed through the first communication passage 32A to the second screw 37 side, and again passed through the second communication passage 32B to the first screw. And the process is repeated until the developer 29 has a predetermined toner concentration.

Next, the toner supply system according to the present embodiment will be described with reference to the flowcharts shown in FIGS. When starting, first, in step 100, the size (size) of the printing paper is selected. A0, A1, A2, A3, A
4, B0, B1, B2, B3, and B4. In the present embodiment, the size of the printing paper is A0, A1,
A description will be given taking four types of A2 and A3 as examples. In this step 100, the size of the print paper (for example, A
After selecting 0, A1, etc., in step 101, the time of the toner density detection timing corresponding to the size of the printing paper is set. The time of the toner density detection timing corresponding to the size of the print paper is an interval (time interval) from when the toner density of the developer 29 is detected to be lower than a predetermined value to when the next toner density is detected. This is set in advance according to the size of the printing paper, and is automatically set by selecting the size of the printing paper. In the present embodiment, the time of the toner density detection timing with respect to the size of the printing paper is 10 seconds when the size of the printing paper is A0.
c, 14 sec when the size of the print paper is A1, 20 sec when the size of the print paper is A2, and 28 sec when the size of the print paper is A3.

In step 101, when the time of the toner density detection timing (for example, print paper A1, 14 sec) corresponding to the size of the print paper is set, in step 102, the developing device 8 is turned on. When the developing device 8 is turned on, the development is started, and the toner density of the developer 29 is detected by the toner density sensor 49 simultaneously with the start of the development. Then, in step 103, the developer 2
It is determined whether the toner density of No. 9 is lower than a preset density, 5% toner density (mixture of 95% by weight of carrier and 5% by weight of toner). Actually, when the voltage value output from the toner density sensor 49 falls below a predetermined value, switching for driving the clutch 42 for supplying toner is performed. Therefore, after the developing device 8 is started, the toner concentration of the developer 29 detected by the toner concentration sensor 49 is set to a predetermined concentration, 5% toner concentration (mixture of 95% by weight of carrier and 5% by weight of toner). If it is higher, monitoring is performed until the toner density of the developer 29 detected by the toner density sensor 49 becomes lower than a preset density.

When the voltage value output from the toner density sensor 49 falls below a predetermined value, that is, at step 103
If it is determined in step 1 that the toner density of the developer 29 is lower than the preset density (5% toner density), step 1
In 04, the number of times that the toner density has become lower than the predetermined value is counted (added). When the number of times of detection of the toner concentration is counted in step 104, the toner is supplied in step 105 for a predetermined period of time (in this embodiment, 0.5 sec). Specifically, the clutch 42 is turned on for 0.5 sec, and the third screw 41 is rotated for 0.5 sec. As a result, the toner corresponding to the movement of the toner when the third screw 41 rotates for 0.5 sec is supplied. That is, the toner supply time is the first time the toner supplied from the toner supply port 35 and stored in the toner storage section 51
The time for rotating the third screw 41 to be conveyed to the tip of the screw 36 is constant regardless of the size of the printing paper. Since the rotation speed of the third screw 41 is constant, the operation time of the third screw 41 is constant, so that one toner supply amount is constant.

In step 105, a predetermined time (0.5
sec) When the toner is supplied and the toner supply is completed, in step 106, the time of the toner concentration detection timing set in step 101 (14 seconds in the case of the print paper A1) is counted. Step 1 in parallel with this
At 07, it is determined whether or not toner is present in the toner storage unit 51. Whether or not toner is present in the toner storage unit 51 is detected by a toner detection sensor 50. The toner detection sensor 50 detects the absence of toner when the toner in the toner storage unit 51 becomes smaller than a predetermined amount. This is to output without toner. Specifically, based on the output voltage when the toner amount is greater than the reference amount, the toner amount is detected based on whether the voltage value detected by the toner detection sensor 50 is higher or lower.

If it is determined in step 107 that there is toner in the toner storage section 51, in step 108, the toner density of the developer 29 detected by the toner density sensor 49 is lower than a preset density (5% toner density). It is determined whether or not the number of times of detection is N1 times (20 times in the present embodiment).
If it is determined in step 108 that the number of times the toner density has been detected has reached N1 times (= 20 times), in step 109, the toner is stuck to the toner detection sensor 50, or the connector of the toner detection sensor 50 is disconnected. It is determined that there is an abnormality in the toner detection sensor 50 (the toner detection sensor is not operating correctly), and an error is displayed (in the present embodiment, "no toner" is displayed). The printing operation is stopped simultaneously with or before or after this error display. Actually, when printing (print paper size A0) with a printing rate of 46% was continued in a state where the connector of the toner absence detection sensor was disconnected, the detection of toner absence was displayed on 25 to 30 sheets. Even if the power / interlock switch is turned ON / OFF as it is, the detection display of the absence of toner is not canceled.
・ Even if the interlock switch was turned ON / OFF, it was counted by integration.

In step 107, the toner storage section 51
When it is determined that there is no toner in the developing device 8, in step 110, the toner density sensor 49 detects that the developer density in the developing device 8 is lower than a preset density (5% toner density), and this number is N2 times (15 times). Times). If it is determined in step 110 that the number of times that the value is lower than the preset value is detected as N2 times, in step 111, the toner density detection timing (toner) corresponding to the print paper size (for example, A1) set in step 101 After detecting that the density is lower than the predetermined value, the time of the interval until the next toner density detection is set to the initial set value (when the print paper size is A
In the case of 1, it is reset to の of 14 sec (7 sec when the size of the printing paper is A1).

That is, if the number of times that the toner density is detected to be lower than the preset toner density becomes N2 times, it is determined that printing with a high printing rate has been performed, and the normal toner supply timing is used as it is. When the toner is supplied, the toner concentration becomes too low and the carrier moves to the photosensitive drum 5. In addition, since the rotation speed of the third screw 41 for supplying the toner is always constant, the amount of one toner supply supplied from the toner storage unit 51 is always constant. Therefore, it is necessary to shorten the timing (interval) of supplying toner to increase the number of times toner is supplied. Therefore, in step 111, the time of the toner density detection timing is changed from the initial setting value of 14 sec when the size of the printing paper is A1 to 7 sec (1/2).

When the time of the toner density detection timing is reset to の of the initial set value in step 111, the toner density of the developer 29 is set to a preset density (predetermined value), that is, 5% in step 112. Toner concentration (mixture of carrier 95% weight ratio and toner 5% weight ratio)
It is determined whether it has become higher. This step 112
When it is determined that the toner density of the developer 29 has become higher than a predetermined density (predetermined value), the number of times that the toner density is detected to be higher than the predetermined value is counted.

In step 113, the process waits until the number of times that the toner density has become higher than the predetermined value (5% toner density) becomes N3 times (three times in the present embodiment), and then the toner density becomes higher than the predetermined value. N3 times (= 3 times) when it is detected that the value has become higher than the value (5% toner density).
Then, in step 114, the time (7 sec) of the toner density detection timing (toner density detection interval) reset in step 111 is returned to the initial set value (14 sec). That is, after resetting the time of the toner density detection timing to １ ／ of the initial set value, when the toner density of the developer 29 is detected, a density higher than the preset density is detected N3 times (= 3 times). It is determined that the print is no longer a print with a high printing rate. Therefore, the time (7 sec) of the toner density detection timing corresponding to the size of the print paper (for example, A1) reset in step 111 is set to the initial set value (14 sec when the size of the print paper is A1). Set again. That is, in step 114, the time of the toner density detection timing is determined by the print paper size A
If 1, set to 14 sec.

In step 112, the developer 29
If it is determined that the toner density is not higher than a preset density (predetermined value), in step 115, a predetermined fixed time (in this embodiment, 0.5 s
ec) Supply toner. Actually, the toner density sensor 4
When the voltage value output from 9 falls below a predetermined value, the clutch 42 for supplying toner is driven for 0.5 sec, and the third screw 41 is rotated for 0.5 sec. In step 115, the toner is supplied for a predetermined time (0.5 sec), and when the toner supply is completed, step 116 is performed.
, The time of the toner density detection timing set in step 111 (in the case of the print paper A1, 7 se
c) is counted. When the time (7 sec) of the toner concentration detection timing is counted in this step 116, in step 117, the preset toner concentration detection time (7 sec in the case of the print paper A1)
It is determined whether or not it has elapsed. In this step 117,
After the toner density is detected, a preset time of the toner density detection timing (in the case of the print paper A1,
7 sec), and at step 118,
It is determined whether or not the developing device 8 is operating, that is, whether or not the developing is being performed. If it is determined in step 118 that the developing device 8 is operating (developing), the process returns to step 112. If it is determined in step 118 that the developing device 8 is not operating (developing), the process returns to step 100.

As a result of the actual printing, it was confirmed that the toner supply could catch up with the current toner supply method until the continuous printing at the 33% print rate, with the printing rate changed little by little (the toner consumption at this time). Was 2.2 g / A0). Also, up to 60% printing rate continuous printing,
According to the present embodiment, it was confirmed that the toner supply could catch up (the toner consumption at this time was 3.8 g / A0). Further, it was confirmed that the supply capacity of the toner cartridge 20 itself was very small up to continuous printing at a printing rate of 60%.

In step 110, the toner density sensor 49 detects that the developer density in the developing device 8 is lower than a preset density (5% toner density), and this number of times is reduced to N2 times (15 times). If it is determined that the toner density has not been detected, in step 119, after detecting the toner density, the process waits until a preset toner density detection time (14 sec in the case of the print paper A1) elapses. After the detection, when a preset toner concentration detection time (14 sec) has elapsed, it is determined in step 120 whether the developing device 8 is operating, that is, whether copying is in progress. If it is determined in step 120 that the developing device 8 is not in operation (during copying), the process returns to step 100 and returns to step 12.
If it is determined at 0 that the developing device 8 is operating (during copying), at step 121, the toner density of the developer 29 is set to a preset density (predetermined value), that is, 5% toner density (carrier 95% weight ratio. (Mixing of 5% by weight of toner).

In step 121, the developer 29
When it is determined that the toner density is lower than the preset density (predetermined value), in step 122, the number of times that the toner density is detected to be higher than the predetermined value is counted. Then, in step 123, the toner is supplied for a predetermined period of time (0.5 sec in this embodiment). Actually, when the voltage value output from the toner density sensor 49 falls below a predetermined value, the clutch 42 for supplying the toner is driven for 0.5 sec.
1 is rotated for 0.5 sec. In this step 123, the toner is supplied for a predetermined time (0.5 sec).
When the toner supply is completed, in step 124, the time of the toner density detection timing set in step 101 (14 sec in the case of the print paper A1) is counted. To the toner storage unit 51 again.
It is determined whether or not the number of times that no toner is detected is N2 times (preset number).

If it is determined in step 121 that the toner density of the developer 29 detected by the toner density sensor 49 has become higher than a preset density (predetermined value), the flow ends because there is no abnormality.

In step 108, the number of times that the toner density of the developer 29 detected by the toner density sensor 49 is lower than the preset density (5% toner density) is N1 times (in this embodiment, Is
If it is determined that the number of times has not reached (20 times), step 125
In step, it is determined whether or not a preset toner density detection time (14 sec in the case of the print paper A1) has elapsed. After the toner density is detected in step 125, the preset toner density detection timing is set. Time of toner concentration detection timing (14 sec for print paper A1)
Is determined, it is determined in step 126 whether the developing device 8 is operating, that is, whether the developing is being performed.
If it is determined in step 126 that the developing device 8 is operating (developing), the process returns to step 103.

If it is determined in step 126 that the developing device 8 is not operating, the process returns to step 100. That is, the state returns to the state before the start of printing. Therefore, the time of the toner density detection timing set based on the size of the print paper (14 in the case of print paper A1,
The toner density detection for each sec) is performed when the developing device 8 is operating, and after detecting that the toner density has become lower than a predetermined value (5% toner density), the time of the next toner density detection timing is determined. When the development is completed (the operation of the developing device 8 is stopped) by 14 seconds (in the case of the print paper A1), the time counting for detecting the toner density is not performed. A1
If an image is formed intermittently one by one with the following print size, the next toner density detection cycle (14
The development is completed before c). In this case, the number of times performed is backed up even when the power is turned off, and is counted by integration when the developing device 8 is operated next time.

FIG. 6 shows another embodiment of a toner supply system when an abnormality is detected in the toner amount detection sensor according to the present invention. FIG. 6 is a side sectional view of a developing device to which the toner supply method is applied when an abnormality of the toner amount detection sensor is detected. In the figure, a casing 61 of a developing device 60 has an opening 62 facing a part of the surface of the photosensitive drum 5.
A developing roller 63 is provided so as to partially expose the peripheral surface from the opening 62 and approach the photosensitive drum 5. The developing roller 63 has a sleeve 64 formed in a cylindrical shape, and a sleeve 64 inside the sleeve 64.
And a magnet 65 arranged separately from the sleeve 64 along the inner peripheral surface of the sleeve 64. The sleeve 64 rotates outside the magnet 65. This developing roller 63
On the outer peripheral surface of the sleeve 64, the developer 66 is attracted by the magnetic force of the magnet 65 to form a magnetic brush. The magnetic brush contacts the surface of the photosensitive drum 5 on which the latent image is formed, and The developer 66 is transferred to the surface and developed.

The casing 61 has two storage chambers 67,
A developing roller 63 is provided in the storage chamber 67.
However, agitators 69 for adsorbing the developer 66 to the developing roller 63 are stored in the storage chambers 68, respectively. Further, the storage chamber 68 is provided with a developer supply port 70 for supplying the developer 66 into the storage chamber 68. A hopper 71 is attached to the developer inlet 70. The hopper 71 stores and stores the developer 66, and supplies the developer 66 to the developing device 60 when the amount of the developer 66 in the developing device 60 becomes equal to or less than a specified value. 7
A developer supply roller 2 is configured to be driven by a hopper motor (not shown). By rotating the developer supply roller 72, the developer 66 is supplied from the developer inlet 70 over substantially the entire area of the storage chamber 68 of the developing device 60. 73 and 74 are stirring rods,
The stirring rods 73 and 74 stir the developer 66 and move the developer 66 to the vicinity of the developer supply roller 72. 75 provided in the casing 61 of the developing device 60
Is a developer detection sensor for detecting whether the amount of the developer 66 filled in the storage chamber 68 below the developer inlet 70 is equal to or more than a certain amount (if there is less than the certain amount, there is no detection). The developer 66 in the storage chamber 68 is detected by the developer detection sensor 75.
When it is detected that the amount of the toner has fallen below a certain amount, the hopper motor is driven to rotate the developer supply roller 72 to move the developer 66 from the developer inlet 70 into the storage chamber 68 of the developing device 60. Supply.

Next, the toner supply system according to the present embodiment will be described with reference to the flowchart shown in FIG. When starting, first, in step 200,
The size (size) of the print paper such as A0, A1, A2, A3, etc. is selected. In the present embodiment, the size of the print paper is described as A1 as an example. This step 2
When the size (A1) of the print paper is selected at 00, the time of the developer absence detection timing corresponding to the size of the print paper is set at step 201. The time of the developer absence detection timing is from the time when the amount of the developer 66 in the storage chamber 68 of the developing device 60 is detected to be lower than the predetermined value, to the time when the developer 66 in the storage chamber 68 of the next developing device 60 is detected. An interval (time interval) until it is detected that the amount falls below a certain value, which is preset according to the size of the printing paper, and is automatically set by selecting the size of the printing paper. In the present embodiment, the time of the developer absence detection timing with respect to the print paper size is determined by the print paper size being A
If 0, 10 sec, if the size of the print paper is A1, 14 sec, if the size of the print paper is A2,
20 sec, 28 s if the print paper size is A3
ec is set.

When the time for detecting the absence of the developer corresponding to the size of the printing paper (for example, printing paper A1, 14 sec) is set in step 201, the developing device 60 is turned on in step 202. When the developing device 60 is turned on, a switch for starting development is turned on, and at the same time as the start of the development, the presence or absence of the developer 66 in the storage chamber 68 of the developing device 60 (the amount of the developer (Above or below a certain value). Then, in step 203,
Whether the amount of the developer 66 in the storage room 68 of the developing device 60 is above or below a predetermined value is determined based on the detection value of the developer detection sensor 75. Whether or not the developer 66 is present in the storage chamber 68 of the developing device 60 is detected by a developer detection sensor 75, and the developer detection sensor 75 detects that the developer 66 is in the storage chamber 68 of the development device 60. When the amount becomes smaller than a predetermined amount, the absence of the developer is detected, and an output indicating that there is no developer is output. Specifically, based on the output voltage when the amount of the developer 66 is larger than the reference amount, the amount of the developer is detected based on whether the voltage value detected by the developer detection sensor 75 is higher or lower. ing. Actually, when the voltage value output from the developer detection sensor 75 falls below a predetermined value, it is determined that there is no developer, and the hopper motor is driven to rotate the developer supply roller 72 to perform development. Agent inlet 7
From 0, the developer 66 is supplied into the storage chamber 68 of the developing device 60.

In step 203, it is determined that the amount of the developer 66 in the storage room 68 of the developing device 60 is lower than the preset amount (the developer 66 in the storage room 68 of the developing device 60).
Is smaller than a predetermined value) and in step 204, the number of times that the amount of the developer 66 has become lower than the predetermined value is counted (added). This step 2
When the number of detections of the absence of the developer is counted (incremented) in step S04, the number of times that the amount of the developer 66 detected by the developer detection sensor 75 is detected to be lower than the preset amount in step 205 is N4 times (this number). In the embodiment, it is determined whether or not the number has reached 20). If it is determined in step 205 that the number of times that the amount of the developer 66 has been detected to be lower than the preset amount has become N4 times (= 20 times), it is determined in step 206 that the developer 66 does not exist in the hopper 71. And
An error is displayed (in the present embodiment, "no toner" is displayed). The printing operation is stopped simultaneously with or before or after this error display. In step 203, it is determined that the amount of the developer 66 in the storage chamber 68 of the developing device 60 is not lower than a preset amount (the developing device 60
When the amount of the developer 66 in the storage chamber 68 exceeds a predetermined value set in advance), and in step 207, whether or not the development is continuously performed, that is, whether or not the development is two or more sheets Is determined. If the development is continuously performed on two or more sheets, the process returns to step 203. If the development is not performed continuously, that is, if the development is performed on one sheet, the process returns to step 100.

In step 205, the developer 66
The number of times that the amount of
If it is determined that the number has not reached four times (= 20 times), in step 208, the time of the developer absence detection timing set in step 201 (14 sec in the case of the print paper A1) is counted.

Then, in step 209, it is determined whether or not a predetermined developer detection timing time (14 sec in the case of the print paper A1) has elapsed. No-agent detection timing time (1 for print paper A1)
After waiting for 4 seconds), in step 210, it is determined whether or not the developing device 60 is operating, that is, is under development. If it is determined in step 210 that the developing device 60 is operating (developing), step 203
Return to

If it is determined in step 210 that the developing device 60 is not operating, the process returns to step 200. That is, the state returns to the state before the start of development. Therefore, the time of the developer absence detection timing set based on the size of the print paper (14 in the case of print paper A1,
The detection of the presence / absence of the developer every sec.
If it is determined in Step 10 that the developing device 60 is not operating, the process returns to Step 200. That is, the state returns to the state before the start of development. Therefore, the detection of the presence / absence of the developer every time of the developer absence detection timing set based on the size of the print paper (14 sec in the case of the print paper A1) is performed when the developing device 60 is operating. After detecting that the amount of the developer 66 has become lower than a certain value, the time of the next developer absence detection timing (in the case of the print paper A1, 14
When the development is completed by (sec) (the operation of the developing device 60 is stopped), the time counting for detecting the presence or absence of the developer is not performed. When the size of the print paper is A0, the time required for developing one sheet is 8.45 sec. When the size of the print paper is A1, the time required for developing one sheet is smaller than A0. Shorter than in the case of.
For this reason, the time (14
The development may be completed before (sec) comes. Even when the development is completed, the number of times when the absence of the developer is detected is backed up even when the power is turned off, and is counted by integration when the developing device 60 is operated next time.

[0057]

According to the first aspect of the present invention, when an erroneous detection is detected in the toner detection sensor, the erroneous detection can be self-diagnosed and appropriate measures can be taken.

According to the second aspect of the present invention, when an erroneous detection is detected by the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

According to the third aspect of the present invention, when an erroneous detection is detected by the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

According to the fourth aspect of the invention, the supply of toner can be caught up even when printing with a large printing rate (toner consumption) continues continuously.

According to the fifth aspect of the present invention, even when printing with a high printing rate (toner consumption) continues continuously, the supply of toner is to be caught up.

According to the sixth aspect of the invention, the supply of toner can be caught up even when printing with a large printing rate (toner consumption) continues continuously.

According to the seventh aspect of the present invention, when an erroneous detection is detected in the toner detection sensor, the erroneous detection can be self-diagnosed and an appropriate measure can be taken.

According to the eighth aspect of the invention, the supply of toner can be caught up even when printing with a high printing rate (toner consumption) continues continuously.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus to which a toner supply system according to the present invention is applied.

FIG. 2 is an enlarged sectional view of the developing device shown in FIG.

FIG. 3 is a plan view of a screw portion of the developing device shown in FIG.

FIG. 4 is a flowchart illustrating a toner supply method of the developing device illustrated in FIG. 2;

FIG. 5 is a flowchart illustrating a toner supply method of the developing device illustrated in FIG. 2;

FIG. 6 is an enlarged sectional view of a developing device to which the toner supply system according to the present invention is applied.

FIG. 7 is a flowchart illustrating a toner supply method of the developing device illustrated in FIG. 6;

[Explanation of symbols]

 5 …………………………………………………………………………………………………………………………………………………………………………………… Developing device 24 ……………………………… …………………………………………………………………………………… Developer 37 …………………………………… First screw 38 ……… …………………………………………………………………………………………… 3rd screw 49 ……………………… Toner Density sensor 50 ...... Toner detection sensor 60 ...... Developing device 61 ............ …………………………………………………………………………………… Opening 63 ……………………… Developing roller 64 ………………… ……………… Sleeve 65 ……………………………… ............ Magnet 66 .................. Developer 67, 68 ...... ...... Storage chamber 69 .................. ………… Agitating roller 70 ………………………………… Developer supply port 71 ………………………………………… hopper hopper 72 ………. …………………………… Developer supply rollers 73, 74 ………………… Stirrer bar 75 ……………………………………… Developer detection Sensor

Claims (8)

[Claims] 1. A developing device provided with a toner storage section for temporarily storing toner supplied by a toner cartridge, wherein a stirring and circulation means provided in the developing device stirs and circulates a developer composed of toner and carrier. The toner concentration of the developer is detected by a toner concentration sensor provided in the developing device, and when the toner concentration of the developer falls below a predetermined value, toner is supplied from the toner reservoir to the developing device. In a toner supply system for detecting the amount of toner in the toner storage unit by a toner detection sensor provided in the toner storage unit, and supplying toner from a toner cartridge when the amount of toner in the toner storage unit falls below a certain amount,
While the toner concentration sensor continuously detects that the toner concentration in the developing device falls below a certain value for a predetermined time or more, and while detecting the toner concentration below the certain value, the toner storage unit Wherein the toner detection sensor does not detect the absence of toner at all, determines that the toner detection sensor is not operating correctly, and displays an error. 2. The toner supply system according to claim 1, wherein the printing operation is stopped simultaneously with or before or after the error display. 3. The toner supply system according to claim 1, wherein a time during which the toner density in the developing device is lower than a predetermined value is integrated by a backup unit. 4. A developing device provided with a toner storage portion for temporarily storing toner supplied by a toner cartridge, wherein a stirring and circulation means provided in the developing device stirs and circulates a developer composed of toner and carrier. The toner concentration of the developer is detected by a toner concentration sensor provided in the developing device, and when the toner concentration of the developer falls below a predetermined value, toner is supplied from the toner reservoir to the developing device. In a toner supply system for detecting the amount of toner in the toner storage unit by a toner detection sensor provided in the toner storage unit, and supplying toner from a toner cartridge when the amount of toner in the toner storage unit falls below a certain amount,
While the toner concentration sensor continuously detects that the toner concentration in the developing device falls below a certain value for a predetermined time or more, and while detecting the toner concentration below the certain value, the toner storage unit The toner detection sensor determines that a print with a high printing rate has been made when the toner detection sensor detects the absence of toner at least once, and changes the toner supply amount per unit time. 5. The toner supply method according to claim 4, wherein the change of the toner supply amount per unit time is such that a toner supply timing is shorter than a current toner supply cycle. 6. When the toner density sensor detects that the toner supply amount exceeds the predetermined value at least once after the change of the toner supply amount, the toner supply amount per unit time is returned to a state before the change. The toner supply system according to claim 4, wherein: 7. The toner supply method according to claim 4, wherein a time during which the toner concentration in the developing device is lower than a predetermined value is integrated by a backup unit. 8. A toner supplied by a toner hopper is agitated by an agitating means provided in a developing device, and a toner sensor provided in the developing device detects a remaining amount of toner consumed by image formation. In a toner supply system for supplying toner from the toner hopper in which the remaining amount falls below a predetermined value, when the toner sensor continuously detects that the remaining amount of toner in the developing device falls below a predetermined value for a predetermined time or more. Judge that a print with a high printing rate has been made, change the toner supply amount per unit time,
Thereafter, when the toner sensor detects that the remaining amount of toner in the developing device exceeds a predetermined value for a set time or more, the toner supply amount per unit time is returned to a state before change. Supply method.