JPH1026876A - Image forming device - Google Patents

Abstract

An object of the present invention is to cause a problem due to an unset or defective setting of a toner concentration detection sensor, a problem due to a non-feeding of a developer, and an erroneous toner density control due to a biased feeding of a developer. Is to solve. The present invention relates to an image forming apparatus main body in which when the output value from the toner density detecting means does not exceed a first predetermined value, the toner density detecting means is not set or the toner density detecting means is abnormal. It is provided with a control means 25 for judging that it has occurred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to an image forming apparatus such as a facsimile.

[0002]

2. Description of the Related Art Image forming apparatuses such as copying machines, printers, and facsimile machines generally form an electrostatic latent image on an image carrier by a latent image forming means by rotating an image carrier such as a photoconductor by a motor. Then, the electrostatic latent image is developed by a developing device to form a toner image, the toner image is transferred to recording paper by a transfer unit, and the toner on the recording paper is fixed by a fixing device. Cleaning is performed by a cleaning device having a cleaning blade or the like.

A developing device develops an electrostatic latent image on an image carrier with a two-component developer composed of toner and carrier, and the developer is supplied from a developer container. The developing device is supplied with toner from a toner supply device. The toner and the carrier are charged by stirring or the like, and the electrostatic latent image on the image carrier is developed by electrostatically attaching the toner by a developing device.

In recent years, a developing device in which a plurality of developer stirring / conveying members for stirring and conveying a two-component developer and a developer carrying member are arranged in a horizontal direction has been widely used. This is because the developing device can be manufactured at a low cost with a simple configuration and can be downsized.
A toner replenishing device for replenishing toner to the developing device is often configured to replenish toner from an end on a developer stirring and conveying member side in order to take advantage of downsizing of the unit.

Further, in the image forming apparatus, the magnetic permeability of a two-component developer in the developing device is detected by a toner density detecting sensor as a toner density detecting means.
The toner concentration of the component developer is detected, the output value of the toner concentration detection sensor is compared with the toner concentration reference value by the toner concentration control means, and the toner replenishing device is controlled based on the result. The toner density reference value is set based on the output value of the toner density detection sensor when the developer is supplied from the developer container to the developing unit.

The developing device is detachably attached to the image forming apparatus main body, the toner density detecting sensor is connected to the image forming apparatus main body by a connector, and the output signal of the toner density detecting sensor is transmitted via the connector to the image forming apparatus. In addition to the output to the main body, a developing bias is applied from a high-voltage power supply to the developer carrier of the developing device via a connector. If the toner density detection sensor is not set, the display unit displays that the toner density detection sensor is not set.

[0007]

In the above-described image forming apparatus, the developing device is detachably attached to the image forming apparatus main body, and the toner density detecting sensor is connected to the image forming apparatus main body by a connector to detect the toner density. The output signal of the sensor is output to the image forming apparatus main body side via the connector, and the developing bias is applied from the high voltage power supply to the developer carrier of the developing apparatus via the connector. Alternatively, if the setting is defective, the developing bias is not normally applied to the developer carrying member, and an abnormal image is output or the toner density control is not normally performed.

Further, when the developer is not charged, no carrier is present in the developing device, so that the toner is not charged and no image is formed at all, but the uncharged toner scatters. If the reference value of the toner density control is set when the developer is not supplied, and the developer is supplied from the developer container after the setting, the toner density is controlled to be high.

Further, when the idle operation (operation for not forming an image) is performed by the operation of the image carrier while the developer is not charged into the developing device from the developer container, the toner is deposited on the image carrier. Without it, the coefficient of friction between the image carrier and the cleaning blade is increased, and abnormalities such as entrainment of the cleaning blade occur. Further, when the output signal of the toner density detection sensor is not output due to the damage of the toner density detection sensor, the toner density detection sensor is normally set no matter how many times the user resets the toner density detection sensor. Nevertheless, the display unit indicates that the toner density detection sensor has not been set, and the user cannot determine that the toner density detection sensor has failed.

If the developer is extremely shifted when the developer is charged from the developer container to the developing device, the developer may not be in a stable state for a predetermined pre-stirring time. When the toner density control is performed at the same time, the toner density control is erroneously controlled, and the image density becomes inappropriate.

According to the present invention, it is possible to solve the problem caused by the unset or defective setting of the toner concentration detecting sensor and the problem caused by the non-feeding of the developer, and to inform the user of the failure of the toner concentration detecting means. It is an object of the present invention to provide an image forming apparatus capable of preventing erroneous toner density control when a developer is displaced from a developer container.

[0012]

According to a first aspect of the present invention, there is provided an image carrier, a latent image forming means for forming an electrostatic latent image on the image carrier, and A developing device for developing the electrostatic latent image on the carrier with a two-component developer;
A toner replenishing device for replenishing toner to the developing device; a toner concentration detecting device for detecting a toner concentration of a two-component developer in the developing device; and a toner replenishing device based on an output value of the toner concentration detecting device. An image forming apparatus comprising: a toner density control unit for controlling the toner density detection unit; and a connection unit that connects the toner density detection unit to the image forming apparatus main body and outputs an output signal of the toner density detection unit to the image forming apparatus main body. A control unit that determines that the toner density detecting unit is not set or the toner density detecting unit is abnormal when the output value from the toner density detecting unit does not exceed a first predetermined value on the image forming apparatus main body side. Therefore, it is possible to solve the problem caused by the unset or defective setting of the toner density detection sensor.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the control means inhibits the image forming operation when the output value from the toner density detecting means does not exceed the first predetermined value. Therefore, it is possible to solve the problem caused by the toner density detection sensor not being set or the setting failure.

The invention according to claim 3 is the invention according to claim 1 or 2
In the image forming apparatus described above, when the output value from the toner density detecting means does not exceed the first predetermined value, the control means displays on the display means that the toner density detecting means is not set. That is, the user can be notified that the toner concentration detecting means is not set.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the control means inhibits the image forming operation when an output value from the toner density detecting means does not exceed the first predetermined value. Even if the user repeatedly performs a predetermined operation, which is considered to have performed the setting of the toner density detecting means, a predetermined number of times, the output value from the toner density detecting means does not exceed the first predetermined value. In this case, the toner density detecting means is determined to be abnormal, and if the toner density detecting means is damaged and does not output an output signal, the user resets the toner density detecting means many times and detects the toner density. It is possible to solve the problem that the user cannot judge the failure of the toner density detecting means even though the means is normally set.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the developing device includes a developing device for charging a developer in a developer container, and the control unit controls the toner density from the toner density detecting unit. When the output value does not exceed the first predetermined value and does not exceed a second predetermined value larger than the first predetermined value, it is determined that the developer has not been supplied to the developing device. It is possible to prevent the occurrence of an abnormality such as the cleaning blade being entangled due to the idling operation when the developer is not charged.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the control means makes the determination after a predetermined time has elapsed after the start of warm-up, and makes the determination accurately. be able to.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the control unit determines that an output value from the toner density detecting unit exceeds the first predetermined value and the first predetermined value is higher than the first predetermined value. The image forming operation is stopped when the value does not exceed the second predetermined value which is greater than the second predetermined value. It is possible to prevent the occurrence of an abnormality such as the cleaning blade being caught by the idle operation in a state where the developer is not supplied to the developing device. it can.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the developing device comprises a developing device for charging a developer in a developer container, and the control means includes a developing device for detecting the toner density. When the output value does not exceed the first predetermined value and does not exceed a second predetermined value which is larger than the first predetermined value, a display means indicates that the developer has not been supplied to the developing device. The user can be informed that the developer has not been charged into the developing device.

According to a ninth aspect of the present invention, in the image forming apparatus of the first aspect, the developing device comprises a developing device for charging a developer in a developer container, and the control means controls the developing device to supply the developer. If the output value from the toner density detecting means does not fall within a predetermined range after the toner density detecting means is initialized after being supplied, it is determined that there is an abnormality, and the developer is shifted from the developer container. It is possible to prevent erroneous toner density control when the toner is supplied.

According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the control means performs the initialization with respect to the toner density detecting means after a developer is supplied to the developing device, and then controls the toner density. When the output value from the detection means does not fall within the predetermined range, an abnormality is displayed on the display means, so that the user can be notified that the developer has been displaced from the developer container.

According to an eleventh aspect of the present invention, in the image forming apparatus according to the first aspect, the developing device comprises a developing device for supplying a developer in a developer container, and the control means controls the developing device to supply the developer. If the output value from the toner density detecting means does not fall within a predetermined range after the toner density detecting means has been initialized after being supplied, the toner density detecting means initializes the initial developer again. When the output value from the toner density detecting means does not fall within a predetermined range, it is determined that the toner density is abnormal. Therefore, the convenience of the user can be improved, and the abnormality of the toner density detecting means can be identified.

[0023]

FIG. 2 shows a developing device according to an embodiment of the present invention. In the image forming apparatus of this embodiment, the image carrier 1 formed of a drum-shaped photoreceptor is rotated in the direction of an arrow by a driving unit during image formation. A developing device 2 covered with a casing is provided at a predetermined portion around the photoconductor 1. The developing device 2 has a predetermined length in a direction penetrating the paper surface in accordance with the photoreceptor 1, and a developing sleeve 5 is disposed closer to the photoreceptor 1 than the opening of the developing device 2, and is rotatably mounted on the shaft. Supported.

Further, a first member 3 and a second member 4 for developer agitating and transporting are arranged in order next to the developing sleeve 5 and are axially supported. The first member 3 and the second member 4 are respectively provided with toner and Many blades having a function of stirring and transporting a two-component developer composed of a carrier are provided. The first member 3 and the second member 4 are rotationally driven by a driving unit to stir and transport the two-component developer, and circulate the two-component developer in the developing device 2 via the developing sleeve 5.

A long opening 6 is formed in a portion of the developing device 2 above a specific region extending between the first member 3 and the second member 4 in a direction penetrating the paper surface. 7 is provided detachably with respect to the developing device 2. The attaching / detaching means for attaching / detaching the developer container 7 to / from the developing device 2 is such that the locking convex portion 7a of the locking convex portions 7a and 7b protruding from the side of the developing container 7 is formed on the developing container 2 side. By adopting a structure in which the developer container 7 is attached to the developing device 2 by inserting into the opening of the locking portion 2a of the locking portions 2a and 2b, hooking the locking projection 7b on the locking portion 2b,
The developer container 7 is detachable from the developing device 2.

FIG. 2 shows a state immediately after the developer container 7 is mounted on the developing device 2. The opening of the developer container 7 is set downward, and this opening is heat-sealed as a sealing member. The developer container 7 is hermetically closed by being closed by 9. Inside the developer container 7, a developer 10 and a dehumidifier 11 are enclosed. In this enclosed state, the developer 10 can flow in the developer container 7 while being simply filled in the developer container 7, but the dehumidifier 11 is provided on the side of the opening 6 provided with the heat seal 9. Since it is fixed to a portion corresponding to the bottom on the opposite side by bonding or the like, it does not drop when mounted in the state of FIG.

The heat seal 9 can be easily pulled out with the developer container 7 attached to the developing device 2 as shown in FIG. When the heat seal 9 is pulled out, the developer container 7 and the developing device 2 are in communication with each other, and the developing container 7
The developing agent 10 falls into the developing device 2 but the dehumidifying agent 11
Remain in the developer container 7. Thus, the developer container 7
Until the heat seal 9 is pulled out, the developer 10 and the dehumidifier 11 are sealed in the developer container 7.

Of the developer that has fallen into the developing device 2, the toner is consumed every time the developer is developed, and new toner is supplied into the developing device 2 from a toner bottle (not shown) in order to supplement the consumed toner. . The developer container 7 includes the developing device 2
After the heat seal 9 is pulled out,
The dehumidifying agent 11 performs a dehumidifying function in the developing device 2, and prevents the developer 10 in the developing device 2 from being reduced in charging characteristics due to humidity.

FIG. 3 shows this embodiment. The developing device 2 is integrally formed with a photoconductor case 13 that supports the photoconductor 1, and these constitute a photoconductor unit 22. The photoreceptor 1 rotating clockwise is first uniformly charged by a charging roller 2 as a charging unit, and is exposed by irradiating exposure light 15 whose intensity is modulated by image information from a writing unit (not shown). Thus, image information is written and an electrostatic latent image is formed.

The electrostatic latent image on the photoreceptor 1 is developed by the developing device 2 by the developing sleeve 5 to become a toner image, and a transfer bias is applied to a transfer roller 16 as a transfer unit from a power supply (not shown). When the transfer paper fed from the paper feeding device passes through the nip portion between the transfer roller 16 and the photoconductor 1, the toner image on the photoconductor 1 is transferred by the transfer roller 16, and the transfer paper is transferred by a fixing device (not shown). The toner image is fixed and discharged to a tray. Such an image forming operation is started by an image forming instruction from an operation panel described later.

On the other hand, after the toner image is transferred, the photosensitive drum 1 is cleaned of residual toner by a cleaning blade 17 as a cleaning means, and is discharged by a discharge light 220 from a discharger (not shown). The residual toner scraped off from the photoreceptor 1 by the cleaning blade 17 falls into a collection container provided in a part of the photoreceptor case 13, and the end of the conveying screw 20 in the axial direction is rotated by the rotation of the conveying screw 20. Is sent to the developing device 2 by the recycling belt 21. The toner sent to the developing device 2 is mixed with new toner from the toner bottle 18 at a screw portion of the second member 4 at the end of the recycling belt 21, mixed with the developer, and sent to the developing sleeve 5. .

The developing device 2 is provided with the developing container 7 detachably as described above. FIG. 3 shows a state before the heat seal 9 is pulled out. In this state, the developer 10 is still in the developing container 7. By withdrawing the heat seal 9 from the developing container 7, the developer 11 in the developing container 7 falls into the developing device 2, and the developer 11 is removed from the first member 3 and the second member 3.
The toner is circulated in the developing device 2 by being stirred by the member 4 and conveyed through the developing sleeve 5. The dehumidifier 11 has a function of dehumidifying the inside of the developing device 3 after the heat seal 9 is pulled out.

Developing device 2 formed above second member 4
The toner in the toner bottle 18 is replenished through the opening indicated by the arrow, and the toner consumed by the development is supplemented. The toner concentration detecting sensor 19 as a toner concentration detecting means detects the toner concentration of the two-component developer in the developing device 2, and for example, detects the magnetic permeability of the two-component developer in the developing device 2 to detect the two components. The toner concentration of the system developer is detected, and the amount of toner supplied from the toner bottle 18 is controlled based on the detection information of the toner concentration detection sensor 19 as described later.

FIGS. 4 and 5 show the appearance of the photosensitive unit 22. FIG. FIG. 4 shows a state in which the developer container 7 is mounted on the developing device 2, and FIG. 5 shows a state in which the developer container 7 of the developing device 2 is removed. As described above, the locking protrusions 7a and 7b are formed on the developer container 7, while the locking portions 2a and 2b combined with the locking protrusions 7a and 7b are formed on the developing device 2. With these combinations, the developer container 7 is made detachable from the developing device 2.

As shown in FIG. 6, the second member 4 is longer outward (frontward) than the first member 3, and a screw is formed in a portion longer than the first member 3. Second member 4
In the area inside the area where the screw is formed, a number of blades 4h each having a shape obtained by cutting an elliptical plate into approximately half are provided obliquely with respect to the axis. Stir according to the rotation and transport at the same time. The transport direction due to the rotation of the second member 4 is the direction of arrow A. Similarly, the first member 3 has a similar blade 3h corresponding to the arrangement region of the blade 4h formed on the second member 4. The inclination of the blade 3h formed on the first member 3 is opposite to the inclination of the blade 4h of the second member 4, and the developer is the first member.
It is sent in the direction of arrow B according to its rotation by the member 3.

A partition plate 24 is provided between the first member 3 and the second member 4, and the partition plate 24 separates the first member 3 from the second member 4. The developing sleeve 1 has a fixed shaft in which five-pole magnets are arranged, and a non-magnetic pipe material covering the outer peripheral surface thereof is driven to rotate by a driving unit (not shown). The developer is sent to the developing sleeve 1 by the magnetic attraction of the developing sleeve 1 while being sent by the first member 3 in the direction of the arrow B according to the rotation.

The remaining developer moves toward the second member 4 from the gap on the near side, which is separated from the partition plate 24, is sent in the direction of arrow A by the second member 4, and is transferred from the gap on the back side of the partition plate 24. Move to the first member 3. Thus, basically, the developer is the first
The member 3 and the second member 4 circulate in a loop with the partition plate 24 therebetween. The developing sleeve 1 magnetically attracts the developer by an internal magnet and conveys the developer along with the rotation. The developer on the developing sleeve 1 is regulated to a certain amount by a doctor blade 9 and the developing sleeve 1 The electrostatic latent image on the photoreceptor 1 is developed when the electrostatic latent image passes between them.

Here, the toner in the toner bottle 18 is replenished into the developing device 2 with the opening / closing lid 23 opened as shown in FIGS. The toner supply position of the developing device 2 is
As shown in FIG. 6, the screw portion formed on the second member 4, that is, on the screw portion 4 a outside the portion where the partition plate 24 and the blade 4 h are formed. The photosensitive member 1 is provided on a screw portion 4b axially outside the screw portion 4a.
The waste toner scraped from the toner is sent by the recycling belt 21 for reuse.

Accordingly, the waste toner is fed into the screw portion 4b of the second member 4, and the new toner sent in the screen portion 4a is mixed with the waste toner, and the waste toner and the new toner are mixed in the loop-shaped circulation path. It is fed into the developer and is agitated and transported by the blades 4h. The toner is in an insufficiently charged state at the initial stage of stirring, and it is not preferable that the insufficiently charged toner crosses the partition plate 24 and is subjected to development. Is set higher than other parts.

As shown in FIG. 1, the toner replenishing device 18 replenishes toner from the toner bottle 18a to the developing device 2 by the operation of a toner replenishing drive portion 18b composed of a motor or a clutch.
Is controlled by a control unit 25 including an image forming apparatus control circuit configured by using Operation panel 26
Has an operation unit and a display unit composed of a number of keys operated by the user. The image forming apparatus control circuit 25 uses the input signals from the toner density detection sensor 19, the operation panel 26, and the like to operate the image forming apparatus. Each unit is controlled to perform an image forming operation and the like as described above. The image forming apparatus control circuit 25 performs an image forming operation on the operation panel 2 according to an input signal from the operation panel 26.
The control is started when an image formation instruction is given in step S6.

The developing device 2 is detachably mounted on the main body of the image forming apparatus (image forming apparatus main body), and is mounted on or removed from the main body of the image forming apparatus by opening a front door. As shown in FIG. 7, the toner density detection sensor 19 is connected to and detachable from the image forming apparatus main body by a connector 27, and the developing sleeve 5 is connected to a high voltage power source on the image forming apparatus main body side by a connector (not shown) so as to be able to contact and separate. A developing bias is applied from a high voltage power supply via a connector. Opening / closing of the front door is detected by a front door switch as front door opening / closing detecting means.

FIG. 8 shows a part of the processing flow of the image forming apparatus control circuit 25. The image forming apparatus control circuit 25 executes the processing shown in FIG. 8 when the main switch of the apparatus is turned on and the power is turned on. First, in step S1, the output value Vt of the toner density detection sensor (density sensor) 19 is output. Is detected, and a predetermined reference value Vo for determining whether the toner density detection sensor 19 is set / not set in step S2 is compared with Vt, for example, 0.15V, and Vt exceeds Vo (when Vt ≧ Vo). Yes) or not. Here, the output value Vt of the toner density detection sensor 19 decreases as the toner density increases, and does not decrease to 0.15 V or 0.50 V no matter how high the toner density is.

The image forming apparatus control circuit 25 determines that Vt ≧ Vo
Otherwise, it is determined that the toner density detection sensor 19 has not been set, and the image forming operation (image formation) is prohibited in step S5, and the image forming operation is performed even if the image forming instruction is given from the operation panel 26. In step S6, the display section of the operation panel 26 displays an abnormal display indicating that "the PCU (photoconductor unit 22) is not set correctly". Therefore, when the toner density detection sensor 19 is not set or is set improperly, even if the developing bias is not normally applied to the developing sleeve, an abnormal image is output or the toner density control is not normally performed. Can be eliminated.

The image forming apparatus control circuit 25 determines that Vt ≧ Vo
If so, it is determined that the toner concentration detection sensor 19 is set correctly, and a warm-up operation is performed in step S3.
4. In the display section of the operation panel 26, "Copy permitted"
Is displayed, and the image forming operation can be started according to the image forming instruction from the operation panel 26. Here, the warm-up operation is an operation of starting up the fixing device, performing preliminary stirring of the developer in the developing device 2, and the like, and may be described as pre-rotation.

Thereafter, the image forming apparatus control circuit 25 detects the output value Vt of the toner density detecting sensor 19 at a predetermined timing, for example, each time the image forming operation for one sheet is completed, and determines that Vt is a predetermined toner density. It is determined whether or not it is equal to or more than the reference value Vref, and when Vt> Vref, the toner supply driving unit 18b is controlled to cause the toner supply device 18 to supply toner to the developing device 2. Note that the toner supply time, V
The voltage values such as t and Vo are values unique to the apparatus, and vary depending on the type of the toner density detection sensor 19 and the configuration of the apparatus.

As described above, this embodiment is an embodiment of the first aspect of the present invention, and forms a photosensitive member 1 as an image carrier and forms an electrostatic latent image on the image carrier 1. A latent image forming means comprising a charging means 14 and an exposure device; a developing device 2 for developing an electrostatic latent image on the image carrier 1 with a two-component developer; and a toner supply for supplying toner to the developing device 2 A toner concentration detecting sensor 19 for detecting a toner concentration of a two-component developer in the developing device 2; and a toner replenishing device based on an output value of the toner concentration detecting device 19. An image forming apparatus control circuit 25 as a toner density control unit for controlling the image forming apparatus 18;
In the image forming apparatus, the image forming apparatus includes a connector 27 serving as a connecting means for connecting the toner density detecting means 19 and the image forming apparatus main body and outputting an output signal of the toner density detecting means 25 to the image forming apparatus main body. When the output value from the toner density detecting means 19 does not exceed the first predetermined value Vo on the forming apparatus main body side, the toner density detecting means 19 is not set or the toner density detecting means 19 is not set.
Since the image forming apparatus control circuit 25 is provided as control means for determining that an abnormality has occurred in the toner density detection sensor, it is possible to eliminate a problem caused by the toner density detection sensor not being set or being improperly set.

This embodiment is an embodiment of the second aspect of the present invention, and in the image forming apparatus according to the first aspect, the image forming apparatus control circuit 25 as the control means includes the toner density detecting circuit. Since the image forming operation is prohibited when the output value Vt from the toner density detection sensor 19 does not exceed the first predetermined value Vo, it is possible to solve the problem caused by the unset or defective setting of the toner density detection sensor. it can.

Further, this embodiment is an embodiment of the invention according to claim 3, and in the image forming apparatus according to claim 1 or 2, the image forming apparatus control circuit 25 as the control means includes the toner When the output value Vt from the toner density detection sensor 19 as the density detection means does not exceed the first predetermined value Vo, the display unit of the operation panel 26 as the display means that the toner density detection means 19 is not set. Displayed on the PCU2.
2 can be signaled that it has not been set (is not set correctly).

FIG. 9 shows a part of the processing flow of the image forming apparatus control circuit 25 according to an embodiment of the present invention. In this embodiment, the PCU is not set correctly in the embodiment according to the first to third aspects of the present invention. When Vt <Vo is maintained for a predetermined number of times, for example, three times, when the opening and closing of the front door and the opening of the front door for 10 seconds or more are repeated, it is determined that an abnormality of the PCU itself has occurred.

In this embodiment, the image forming apparatus control circuit 2 according to the embodiment of the first to third aspects of the present invention.
In step S5, the counter n is cleared to 0 in step S7 before step S5, the process proceeds from step S6 to step S8, and the front door is opened and closed by an input signal from the front door switch and remains open for 10 seconds or more. If not, the process returns to step S5 if the front door is not opened or closed.

The image forming apparatus control circuit 25 determines that the front door is 1
If it is kept open for more than 0 seconds, the output value Vt of the toner density detection sensor (density sensor) 19 is determined in step S9.
Is detected, and in step S10, the toner concentration detection sensor 19
Predetermined reference value Vo for determining set / unset of
And Vt are compared to determine whether Vt has exceeded Vo (Vt ≧ Vo).

The image forming apparatus control circuit 25 determines that Vt ≧ Vo
If Vt ≧ Vo, the process returns to step S3. In step S11, the counter n is incremented. In step S12, it is determined whether the counter n has reached a predetermined value, for example, 3 or more. If the counter n has not reached 3, the image forming apparatus control circuit 25 returns to step S5. If the counter n has reached 3 or more, the display section of the operation panel 26 displays "The density sensor has failed. Please contact me. "

Therefore, when the toner density detecting sensor 19 is damaged and does not output an output signal, the user may reset the toner density detecting sensor 19 many times and the toner density detecting sensor 19 may be set normally. Regardless, the problem that the user cannot determine the failure of the toner concentration detection sensor 19 can be solved.

As described above, this embodiment is an embodiment of the invention according to claim 4, and in the image forming apparatus according to claim 3, the image forming apparatus control circuit 25 as the control means is provided with the toner It is considered that the image forming operation was prohibited when the output value Vt from the toner density detecting sensor 19 as the density detecting means did not exceed the first predetermined value Vo, and the user set the toner density detecting means 19. Even if a predetermined operation (opening / closing of the front door, opening of the front door for 10 seconds or more) is repeated a predetermined number of times, the output value Vt from the toner density detecting means 19 does not exceed the first predetermined value Vo. In some cases, it is determined that the toner density detecting means 19 is abnormal. Therefore, when the toner density detecting means is damaged and does not output an output signal, the user sets the toner density detecting means many times. Toner concentration detection means again can be user despite being normally set to solve the problem of unable to determine the failure of the toner concentration detecting means.

FIG. 10 shows a part of the processing flow of the image forming apparatus control circuit 25 according to an embodiment of the present invention. According to this embodiment, the image forming apparatus control circuit 2 according to the embodiment of the first to third aspects of the present invention.
5 is from step S2 to step S if Vt ≧ Vo.
Proceeding to 14, it is determined whether or not the initial agent initialization mode for setting the toner density reference value Vref is set. The initial agent initialization mode is set by the operation panel 26 after the user inserts the developer into the developing device 2 from the developer container 7 by attaching the developer container 7 to the developing device 2 and pulling out the heat seal 9. .

The image forming apparatus control circuit 25 proceeds to step S3 if the mode is not the initial agent initialization mode but the normal mode, and performs the above-described processing. In addition, in the initial developer initialization mode, the image forming apparatus control circuit 25 causes the developer stirring / transporting drive unit that rotates the developer stirring / transporting members 3 and 4 in the developing device 2 in step S15 to operate for a predetermined time, for example, 20 sec. By actuating, the developer is agitated.

Next, the image forming apparatus control circuit 25 detects the output value Vt of the toner density detecting sensor 19 in step S16, and determines in step S17 the reference value V for judging whether or not the developer is supplied to the developing device 2. Vt ≧ compared ₁
It is determined whether V _1. Here, V ₁ > Vo, and V ₁ is set to, for example, 0.50V.

The image forming apparatus control circuit 25 determines that Vt ≧ V ₁
If not, that is, if V ₁ > Vt ≧ Vo, it is determined that the developer has not been charged from the developing container 7 into the developing device 2 and the image forming operation (image formation) is forcibly prohibited in step S20. So that the image forming operation is not performed even when the image forming instruction is given from the operation panel 26,
In step S21, the display section of the operation panel 26 displays an abnormal display indicating that "the developer is not set". The user inputs the developer from the developing container 7 into the developing device 2 upon seeing the abnormality display.

Further, the image forming apparatus control circuit 25 outputs Vt
≧ If V ₁ output value Vt of the toner density detection sensor 19 in step S18 is to adjust the control voltage of the toner concentration detecting sensor 19 to a predetermined value, for example 2V, ends the initial developer initialization mode in step S19 After the normal mode is set, the process jumps to step S3.

FIG. 11 shows a part of the processing flow of the image forming apparatus control circuit 25 according to another embodiment of the present invention. In this embodiment, the processing before step S17 is the same as that of the first to third embodiments. In this embodiment, the image forming apparatus control circuit 25 according to the embodiment of the first to third aspects of the present invention.
, Similar to the embodiment of the invention according to the claims 1 to 3 if Vt ≧ V ₁ at step S17 step S1
8, S19, S3 and S4 are executed.

[0061] Further, the image forming apparatus control circuit 25, step counter m at Vt ≧ V ₁ Otherwise step S22 in step S17 is reset to 0 S20, S
Step S21 is executed. In step S23, it is determined whether or not the front door is opened and closed by the input signal from the front door switch and remains open for 10 seconds or more. If the front door is not opened or closed, the process returns to step S20.

The image forming apparatus control circuit 25 determines that the front door is 1
If it is kept open for more than 0 seconds, step S24
The developer stirring / conveying drive unit for rotating the developer stirring / conveying members 3 and 4 in the developing device 2 is operated for a predetermined time,
The developer is agitated by the second operation. Then, the apparatus control circuit 25 detects the output value Vt of the toner density detection sensor (density sensor) 19 at step S25, Vt exceeds V ₁ by comparing the Vt and V ₁ at the step S26 ( Vt ≧ V ₁ ).

The image forming apparatus control circuit 25 determines that Vt ≧ V ₁
Returning to step S18 if, else Vt ≧ V _1, that is, V _1> step S27 it is determined that if Vt ≧ Vo abnormality of the toner concentration detecting sensor 19 has occurred
In step S28, it is determined whether the counter m has reached a predetermined value, for example, 2 or more. The image forming apparatus control circuit 25 determines that the counter m is 2
If the counter m has not reached 2, the process returns to step S20,
If so, the operation panel 2 is selected in step S29.
Display an abnormal message "The concentration sensor is out of order. Please contact service." Here, when the developer is not charged into the developing device 2 and the idle operation is performed many times (operating predetermined portions of the photoconductor 1, the developing device 2, etc. without performing image formation), the cleaning is performed. Since blade 17a is likely to be damaged,
When the counter m reaches 2, the process proceeds to step S29.

In some cases, the developer has not been charged from the developer container. Further, when the output signal of the toner density detection sensor is not output due to the damage of the toner density detection sensor, the toner density detection sensor is normally set no matter how many times the user resets the toner density detection sensor. Nevertheless, the display unit indicates that the developer has not been set, and at this time, the user can determine that the toner concentration detection sensor has failed.

As described above, the embodiments of the present invention according to claims 5 to 8 are embodiments of the invention according to claim 5, and in the image forming apparatus according to claim 1, the developing device 2 An image forming apparatus control circuit 25 serving as the control means, comprising a developing device for charging the developer in the developer container 7;
Is the development when the toner density output value Vt of the toner density detection sensor 19 as a detecting means first does not exceed the predetermined value Vo is greater than the second predetermined value V ₁ of the predetermined value exceeds the Vo and first Since it is determined that the developer has not been charged into the apparatus 2, it is possible to prevent occurrence of an abnormality such as the cleaning blade being entangled due to idle operation in a state where the developer is not loaded into the developing apparatus.

The embodiments of the present invention according to claims 5 to 8 are the embodiments of the invention according to claim 6,
6. The image forming apparatus according to claim 5, wherein the image forming apparatus control circuit 25 as the control unit makes the determination after a predetermined time (preliminary stirring time in steps S15 and S24) has elapsed after the start of warm-up. The above determination can be made accurately.

The embodiments of the present invention according to claims 5 to 8 are the embodiments of the invention according to claim 7,
2. The image forming apparatus according to claim 1, wherein the image forming apparatus control circuit as the control unit determines that an output value from the toner density detecting sensor as the toner density detecting unit exceeds the first predetermined value Vo and the output value is higher than the first predetermined value Vo. since the image forming operation is stopped when the first does not exceed the predetermined value Vo is greater than the second predetermined value V _1, the occurrence of abnormality such as entrainment of the cleaning blade by the air-fuel operation in a developer non-charged state to the developing device It can be prevented beforehand.

The embodiments of the invention according to claims 5 to 8 are the embodiments of the invention according to claim 8,
The image forming apparatus according to claim 7, wherein the developing device (2) is provided.
Consists of a developing device for charging the developer in the developer container 7,
The image forming apparatus control circuit 25 serving as the control unit includes a toner density detection sensor 19 serving as the toner density detection unit.
Output value exceeds the first predetermined value Vo and the first
Since the developer in the developing device 2 is displayed on the display unit of the operation panel 26 as a display unit that is not yet turned on when the not exceed the predetermined value Vo is greater than the second predetermined value V _1, developing the user The apparatus can be notified that the developer has not been charged.

FIG. 12 shows a part of the processing flow of the image forming apparatus control circuit 25 in one embodiment of the present invention. In this embodiment, the processing before step S17 is the same as the embodiment of the invention according to claims 1 to 3, and steps S17 to 29 and steps S17 to 19 are performed.
Is the same as in the other embodiments of the invention according to claims 5 to 8.

In this embodiment, in another embodiment of the present invention, the image forming apparatus control circuit 25 proceeds from step S19 to step S30, where the control of the toner density detection sensor (density sensor) 19 is performed. The output value Vt is detected, and it is determined in step S31 whether or not Vt falls within a predetermined range, for example, a range of 1.8V to 2.2V. The image forming apparatus control circuit 25 determines that Vt is 1.8 V or higher.
If it is within the range of 2.2 V, steps S3 and S4 are executed in the same manner as in the other embodiments of the present invention.

The image forming apparatus control circuit 25 determines that Vt is 1.
If not within the range of 8V to 2.2V, step S3
In step S2, the image forming operation (image formation) is prohibited so that the image forming operation is not performed even if the image forming instruction is issued from the operation panel 26. In step S33, "Please re-initialize the developer" is displayed. An abnormality display is performed on the display unit of the operation panel 26. The user sets the initial agent initialization mode using the operation panel 26 after seeing the abnormal display.

Thereafter, the image forming apparatus control circuit 25 determines whether or not the initial agent initialization mode has been set (turned on) in step S34, and returns to step S32 if the initial agent initialization mode has not been set. When the initial agent initialization mode is set, the image forming apparatus control circuit 25 changes the control voltage of the toner density detection sensor 19 so that the output value Vt of the toner density detection sensor 19 becomes a predetermined value, for example, 2 V in step S35. Adjustment is performed, and the initial agent initialization mode is ended in step S36 to return to the normal mode.

Next, the image forming apparatus control circuit 25 controls the toner density detection sensor (density sensor) 19 in step S37.
Is detected, and it is determined in step S38 whether or not Vt is in the range of 1.8 V to 2.2 V. The image forming apparatus control circuit 25 determines that Vt is 1.8 V or higher.
If it is within the range of 2.2 V, a warm-up operation is performed in step S39. After the warm-up operation is completed, "copy permitted" is displayed on the display of the operation panel 26 in step S40, and the operation panel 26 is displayed. It is possible to start an image forming operation in response to an image forming instruction from the user.

Further, the image forming apparatus control circuit 25 determines that Vt
If is not within the range of 1.8V to 2.2V, it is determined that an abnormality has occurred in the toner density detection sensor 19, and in the step S41, the display section of the operation panel 26 displays "The density sensor has failed. Please contact me. "

As described above, this embodiment is an embodiment of the ninth aspect of the present invention, and in the image forming apparatus according to the first aspect, the developing device 2 puts the developer in the developer container 7. An image forming apparatus control circuit 25 serving as the control unit, the toner density detection sensor serving as the toner density detection unit after initializing the toner density detection unit after a developer is supplied to the development device; If the output value Vt from 19 is not within a predetermined range (range of 1.8 V to 2.2 V), it is determined that there is an abnormality. Control can be prevented.

This embodiment is an embodiment of the tenth aspect of the present invention, and in the image forming apparatus according to the ninth aspect, the image forming apparatus control circuit 25 as the control means includes the developing device 2. After the developer is supplied to the toner concentration detecting means, the output value Vt from the toner concentration detecting sensor 19 serving as the toner concentration detecting means is initialized within a predetermined range (1.8 V to 2.0 V).
If it does not fall within the range (2 V range), the abnormality is displayed on the display section of the operation panel 26 as a display means, so that the user can be notified that the developer has been displaced from the developer container in one direction.

FIG. 13 shows a part of a processing flow of the image forming apparatus control circuit 25 according to an embodiment of the present invention. In this embodiment, the image forming apparatus control circuit 2 according to the embodiment of the ninth and tenth aspects of the present invention.
5 omits steps S32 and S33 and proceeds to step S3
The process proceeds from step 1 to step S34, and if the initial agent initialization mode is not set, step S34 is repeatedly executed.

Therefore, when the output value Vt of the toner density detection sensor 19 does not fall within the range of 1.8 V to 2.2 V, the user sets the initial agent initialization mode. For this reason, when the toner concentration detection sensor is damaged, the user can judge the failure of the toner concentration detection sensor without setting the initial agent initialization mode many times, thereby improving the convenience of the user. An abnormality of the toner density detecting means can be identified.

As described above, an embodiment of the present invention according to claim 11 is the image forming apparatus according to claim 1,
The developing device 2 comprises a developing device for supplying a developer in a developer container 7, and an image forming apparatus control circuit 25 as the control means controls the toner density detecting means after the developer is supplied to the developing device 2. After the initialization, the output value Vt from the toner density detecting sensor 19 as the toner density detecting means is set to a predetermined range (1.8 V to 1.8 V).
When it does not fall within the range of 2.2 V, the initial value is again set in the developing device 2: after initializing, the output value Vt from the toner density detecting means 19 is still within a predetermined range (1.8 V to 2.V). If it does not fall within the range (2V range), it is determined that there is an abnormality. Therefore, the convenience of the user can be improved, and the abnormality of the toner density detecting means can be identified. In addition,
The invention according to each claim is not limited to the above embodiments, and can be applied to, for example, image forming apparatuses other than the above embodiments, such as copying machines, printers, and facsimile machines.

[0080]

As described above, according to the first aspect of the present invention, an image carrier, a latent image forming means for forming an electrostatic latent image on the image carrier, and a static image on the image carrier are provided. A developing device that develops the electrostatic latent image with a two-component developer, a toner replenishing device that replenishes toner to the developing device, and a toner concentration detecting unit that detects the toner concentration of the two-component developer in the developing device ,
A toner density control means for controlling the toner replenishing device based on an output value of the toner density detection means; and connecting the toner density detection means and the image forming apparatus main body to output the output signal of the toner density detection means to the image. Connecting means for outputting to the image forming apparatus main body, when the output value from the toner density detecting means on the image forming apparatus main body side does not exceed a first predetermined value, the toner density detecting means is not set. Alternatively, since a control unit is provided for determining that an abnormality has occurred in the toner density detecting unit, it is possible to solve a problem caused by a non-set or defective setting of the toner density detecting sensor.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control means performs an image forming operation when an output value from the toner density detecting means does not exceed the first predetermined value. Is prohibited, it is possible to solve the problem caused by the unset or defective setting of the toner density detection sensor.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the control unit is configured to execute the control when the output value from the toner density detecting unit does not exceed the first predetermined value. The fact that the toner density detecting means is not set is displayed on the display means, so that the user can be notified that the toner density detecting means is not set.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the control means performs an image forming operation when an output value from the toner density detecting means does not exceed the first predetermined value. And the output value from the toner density detecting means does not exceed the first predetermined value even if the user repeatedly performs a predetermined operation which is considered to have set the toner density detecting means a predetermined number of times. Is satisfied, the toner density detecting means is determined to be abnormal, so if the toner density detecting means is damaged and no output signal is output, the user resets the toner density detecting means many times and detects the toner density. It is possible to solve the problem that the user cannot judge the failure of the toner density detecting means even though the means is normally set.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the developing device comprises a developing device for charging a developer in a developer container, and the control means includes the toner concentration detecting means. When it is determined that the developer has not been supplied to the developing device when the output value from the above does not exceed the first predetermined value and does not exceed a second predetermined value which is larger than the first predetermined value. It is possible to prevent the occurrence of an abnormality such as the cleaning blade being entangled due to the idling operation when the developer is not charged.

According to the sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the control unit makes the determination after a predetermined time has elapsed after the start of warm-up, so that the determination is made accurately. be able to.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the control unit determines that an output value from the toner density detection unit exceeds the first predetermined value and the first output value is higher than the first predetermined value. Since the image forming operation is stopped when the second predetermined value which is larger than the predetermined value is not exceeded, it is possible to prevent the occurrence of an abnormality such as the cleaning blade being caught by the idle operation in a state where the developer is not charged into the developing device. it can.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the developing device comprises a developing device for charging a developer in a developer container, and the control means includes the toner density detecting means. When the output value from the printer does not exceed the first predetermined value and does not exceed a second predetermined value which is larger than the first predetermined value, it is displayed on the display means that the developer has not been supplied to the developing device. The user can be informed that the developer has not been charged into the developing device.

According to the ninth aspect of the present invention, in the image forming apparatus according to the first aspect, the developing device comprises a developing device for charging a developer in a developer container, and the control means controls the developing device to perform development. When the output value from the toner density detecting means does not fall within a predetermined range after the toner density detecting means is initialized after the developer is supplied, it is determined that the toner concentration is abnormal. It is possible to prevent erroneous toner density control when the toner is supplied.

According to the tenth aspect, in the ninth aspect,
In the above-described image forming apparatus, when the control unit performs initialization on the toner density detection unit after the developer is supplied to the development device, and the output value from the toner density detection unit does not fall within a predetermined range. Is displayed on the display means, so that the user can be notified that the developer has been displaced from the developer container.

According to the eleventh aspect, in the first aspect,
In the above-described image forming apparatus, the developing device includes a developing device that supplies a developer in a developer container, and the control unit initializes the toner concentration detecting unit after the developer is supplied to the developing device. Later, when the output value from the toner density detecting means does not fall within the predetermined range, the toner density detecting means is again initialized with respect to the initial developer, and the output value from the toner density detecting means is still within the predetermined range. When it does not enter, it is determined that there is an abnormality, so that the convenience of the user can be achieved, and the abnormality of the toner density detecting means can be identified.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of the invention according to claims 1 to 3;

FIG. 2 is a cross-sectional view illustrating the developing device of the embodiment.

FIG. 3 is a sectional view showing the same embodiment.

FIG. 4 is a perspective view showing the same embodiment.

FIG. 5 is a partially cutaway perspective view showing the same embodiment.

FIG. 6 is a perspective view showing a state where the developing container of the embodiment is removed.

FIG. 7 is a cross-sectional view showing a part of the same embodiment.

FIG. 8 is a flowchart illustrating a part of a processing flow of an image forming apparatus control circuit according to the first embodiment.

FIG. 9 is a diagram showing a part of a processing flow of an image forming apparatus control circuit in one embodiment of the invention according to claim 4;

FIG. 10 is a diagram showing a part of a processing flow of the image forming apparatus control circuit in one embodiment of the invention according to claims 5 to 8;

FIG. 11 is a flowchart showing a part of a processing flow of an image forming apparatus control circuit in another embodiment of the invention according to claims 5 to 8;

FIG. 12 is a flowchart showing a part of the processing flow of the image forming apparatus control circuit in one embodiment of the invention according to claims 9 and 10;

FIG. 13 is a flowchart illustrating a part of a processing flow of an image forming apparatus control circuit according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing device 14 Charging roller 16 Transfer roller 18 Toner replenishing device 19 Toner density detection sensor 25 Image forming device control circuit 26 Operation panel

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Kenzo Tatsumi 1-3-6 Nakamagome, Ota-ku, Tokyo・ Ricoh Co., Ltd. (72) Inventor Toshitaka Yamaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Ricoh Co., Ltd. (72) Takeo Suda Inventor 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Stock Inside Ricoh Company (72) Inventor Ken Amamiya 1-3-6 Nakamagome, Ota-ku, Tokyo / Stock Company Ricoh Company (72) Mayumi Ohori 1-3-6 Nakamagome, Ota-ku, Tokyo Company / Ricoh Company Inside

Claims (11)

[Claims] An image carrier, a latent image forming means for forming an electrostatic latent image on the image carrier, and a developing device for developing the electrostatic latent image on the image carrier with a two-component developer A toner replenishing device for replenishing toner to the developing device, a toner concentration detecting device for detecting a toner concentration of a two-component developer in the developing device, and a toner replenishing device based on an output value of the toner concentration detecting device. An image forming apparatus comprising: a toner density control unit that controls a replenishing device; and a connection unit that connects the toner density detection unit and the image forming apparatus main body and outputs an output signal of the toner density detection unit to the image forming apparatus main body. In the apparatus, when the output value from the toner density detecting means does not exceed a first predetermined value on the image forming apparatus main body side, the toner density detecting means is not set or the toner density detecting means is abnormal. An image forming apparatus characterized by comprising: control means for determining that. 2. An image forming apparatus according to claim 1, wherein said control means inhibits an image forming operation when an output value from said toner density detecting means does not exceed said first predetermined value. Image forming device. 3. The image forming apparatus according to claim 1, wherein said control means determines that said toner density detecting means is not set when an output value from said toner density detecting means does not exceed said first predetermined value. An image forming apparatus characterized in that the display means displays the fact. 4. An image forming apparatus according to claim 3, wherein said control means inhibits an image forming operation when an output value from said toner density detecting means does not exceed said first predetermined value.
When the output value from the toner density detecting means does not exceed the first predetermined value even if the user repeatedly performs a predetermined operation, which is considered to have set the toner density detecting means, a predetermined number of times. An image forming apparatus, wherein the toner density detecting unit determines that the toner density is abnormal. 5. The image forming apparatus according to claim 1, wherein said developing device comprises a developing device for charging a developer in a developer container, and said control means controls said output value from said toner density detecting means to said first value. An image forming apparatus which determines that the developer has not been supplied to the developing device when the predetermined value does not exceed a second predetermined value which is larger than the first predetermined value. 6. An image forming apparatus according to claim 5, wherein said control means makes said determination after a predetermined time has elapsed after the start of warm-up. 7. An image forming apparatus according to claim 1, wherein said control means outputs a second predetermined value which is greater than said first predetermined value and larger than said first predetermined value. An image forming apparatus, wherein an image forming operation is stopped when the value does not exceed a value. 8. An image forming apparatus according to claim 7, wherein said developing device comprises a developing device for charging a developer in a developer container, and said control means controls the output value from said toner density detecting means to said first value. An image forming apparatus for displaying on the display means that the developer has not been supplied to the developing device when the predetermined value does not exceed a second predetermined value which is larger than the first predetermined value. 9. An image forming apparatus according to claim 1, wherein said developing device comprises a developing device for supplying a developer in a developer container, and said control means controls said toner after the developer is supplied to said developing device. An image forming apparatus characterized in that if an output value from the toner density detecting means does not fall within a predetermined range after the initialization of the density detecting means, the image forming apparatus is determined to be abnormal. 10. The image forming apparatus according to claim 9, wherein
The control means displays an abnormality on the display means when the output value from the toner concentration detection means does not fall within a predetermined range after the toner density detection means is initialized after the developer is supplied to the developing device. An image forming apparatus comprising: 11. An image forming apparatus according to claim 1, wherein:
The developing device includes a developing device that supplies a developer in a developer container, and the control unit performs initialization with respect to the toner concentration detecting unit after the developer is supplied to the developing device, and then executes the initialization from the toner concentration detecting unit. If the output value does not fall within the predetermined range, the toner density detecting means initializes the initial developer again. If the output value from the toner density detecting means does not fall within the predetermined range, it is determined that the toner density is abnormal. An image forming apparatus comprising: