JP3342594B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0000]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer. For more information,
An image carrier, a developing device that visualizes a latent image formed on the image carrier with a two-component developer including a carrier and a toner, and a toner storage unit that stores toner to be supplied into the developing device; The present invention relates to an image forming apparatus comprising: a toner replenishing unit for replenishing toner from the toner storage unit into the developing device; and a display unit for detecting a shortage of toner remaining amount or a decrease in toner density and prompting toner replenishment. .

[0001]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer using a two-component developer, an electrostatic latent image formed on an image carrier is visualized with toner in the two-component developer. The toner image is transferred onto a transfer material to form an image. In such an image forming apparatus, it is indispensable to always maintain a proper toner concentration in the developing device in order to form a good image. Therefore, in addition to replenishing a fixed amount of toner during the image forming operation, a reference image is formed on the image carrier after development, and the image density is detected by the optical detecting means. There is disclosed an apparatus in which the toner density is controlled by replenishing toner from a toner storage section into a developing device (for example, see Japanese Patent Application Laid-Open No. 2-304471).

Further, in an image forming apparatus employing such a toner density control method, when toner is consumed by an image forming operation and the amount of toner in a toner container becomes insufficient (hereinafter referred to as toner end), the image forming apparatus is provided with an image forming apparatus. As a method for detecting the state and a method for releasing the toner end, the determination is made by detecting the image density of the reference image formed on the image carrier by the optical detection means and detecting a change in the image density. A device provided with a function is known (for example, see Japanese Patent Application Laid-Open No. 5-150646).

[0003]

However, in an image forming apparatus for forming the reference image on the image carrier using the optical detecting means for detecting and canceling the toner end, an image forming operation is performed. In addition, there is a problem that the toner is consumed even when the reference image is formed. Further, for example, when the optical density detecting means is stained with toner or the like, or the photoreceptor unevenness or rotation unevenness of the image carrier occurs, a background portion optical density value serving as a reference value for releasing toner end, Variations occur in the optical density values detected after toner replenishment, which causes a problem that the toner is not actually replenished but is erroneously detected as replenished. There was a problem that it could not be released correctly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of canceling a display for notifying a lack of toner without wasting toner as much as possible. It is.

[0005]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a two-component developing device comprising: an image carrier; and a latent image formed on the image carrier; a developing device for visualizing the agent, a toner accommodating portion for accommodating the toner to be replenished into the developing device, a toner replenishing means for replenishing the toner into the developing device from the toner accommodating portion, of the image bearing member Optical density detector that detects optical density
And a step, based on a detection result by the optical density detecting means.
Information that the toner container is out of toner
An image forming apparatus comprising: a control unit that causes the display unit to display the information;
The detection result of the optical density of the background portion of the image carrier is a predetermined reference.
When the value is reached, the display of the information by the display means is canceled.
So as to implement a control that is characterized in the this which constitutes the control means.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, after the information is displayed and the toner
Above toner is replenished over accommodating portion is detected by the optical density detection means before being replenished into the developing device
It is supplemented with an optical density of the image carrier background portion and removing reference value of the display of the information, and the release reference value, in the toner storage portion
After the supplied toner is supplied to the developing device, the optical density
Of the background of the image carrier detected by the degree detecting means
Based on the comparison result between the academic concentrations above by the display means
Control to cancel the display of the information
That you have configured the control unit in which the features.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, after the information is displayed, the upper
Serial supplemented to the toner accommodating portion the toner is detected by the optical density detection means before being replenished into the developing device
The value corresponding to the optical density that is higher than the optical density of the background portion of the image carrier by a predetermined density is set as a release reference value for displaying the information, and the release reference value and the replenishment of the toner containing portion are performed.
After the toner is supplied to the developing device, the optical density detection is performed.
Optical density of the background of the image carrier detected by the output means.
Based on the comparison result between degrees, the information by the display means
Control to cancel the display of information
And it is characterized in the this which constitutes the means.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a toner replenishing operation from the toner container to the developing device is performed. The developer stirring operation is configured to be able to be performed independently, and control is performed to stop the developer stirring operation after toner replenishment until the toner replenishment operation is completed.
The above control means is constituted.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a toner replenishing operation from the toner container to the developing device is performed. The control means is configured to be capable of performing the developer stirring operation independently of each other, and to perform control for delaying the developer stirring operation after toner replenishment by a predetermined time from the start of the toner replenishment operation. It is characterized by doing.

[0010]

In the image forming apparatus according to the first aspect of the present invention, after the toner is replenished into the toner storage section based on the display of the display means, the toner is transferred from the toner storage section into the development apparatus by driving the development apparatus. Is supplied to the image carrier while stirring the supplied toner in the developing device, and adheres to the background portion. At this time, the optical density of the background portion is detected by the detection means. Then, when the detected value reaches a predetermined reference range due to the decrease in the optical density, it is regarded that the toner has been replenished by the control means, and the display urging the replenishment of the toner is cancelled.

Further, in the image forming apparatus according to the present invention, the optical density of the background portion of the image carrier after the display by the display means and before the replenished toner is replenished into the developing device. Is detected and stored in a storage device or the like of the control means, and the detected value is used as a reference value for canceling the display by the display means. Then, after the toner is supplied into the developing device, the optical density of the background portion of the image carrier is detected again, the detected value is compared with the release reference value, and when a predetermined condition is satisfied, the display is displayed. Control to release.

Further, in the image forming apparatus according to the third aspect, the amount of variation of the detection value by the optical density detecting means caused by the rotation unevenness of the image carrier or the unevenness of the photosensitive member is obtained in advance by an experiment or the like. Then, after the display by the display means, the optical density of the background portion before toner supply to the developing device is detected. Further, a value corrected to a value corresponding to an optical density higher than a predetermined density is stored in accordance with a variation amount obtained in advance from the detected value, and is set as a reference value for canceling the display. After the toner is replenished, the optical density of the background portion of the image carrier is detected again, the detected value is compared with the reference value, and when a predetermined condition is satisfied, the display is controlled to be released.

Further, in the image forming apparatus of the present invention, the driving of the developing device is stopped until the toner replenishment is completed, and the replenished toner is not agitated and the charging is insufficient. Then, by driving the developing device after the completion of the toner replenishment, the insufficiently charged toner is excessively adhered to the image carrier. Thereby, the optical density of the background portion of the image carrier is significantly changed before and after toner replenishment, thereby facilitating the detection by the detection means and reliably canceling the display by the display means.

In the image forming apparatus according to the present invention, the driving of the developing device is delayed by a predetermined time from the start of toner supply. As a result, the toner replenished during the predetermined time exists in the developing device in a state where the toner is not sufficiently mixed with the carrier component in the developing device. In this state, after a predetermined time has elapsed, the developing device is driven to supply the toner onto the image carrier. When the toner is not sufficiently mixed with the carrier component due to insufficient agitation, the toner that remains insufficiently charged remains on the image carrier. Since the toner adheres in a large amount, the optical density of the background portion of the image carrier significantly changes before and after toner replenishment, thereby facilitating detection by the detection unit and reliably canceling the display by the display unit. I do.
Note that the predetermined time is a length necessary to cancel the display, and the toner can be charged to a desired charge amount immediately after the driving of the developing device is started, and the image forming operation can be started. Such time is determined in advance by experiments or the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment. A document placed on a document table (not shown) is exposed to light by an exposure device (not shown), and the reflected light is projected onto a photoreceptor 1 as an image carrier via a mirror and a lens (not shown). 1 to form a latent image of the original. Around the photoconductor 1, a charging device 6 for uniformly charging the surface of the photoconductor 1, a developing device 2 for visualizing a latent image formed on the photoconductor 1, and a photoconductor for developing the visualized image A transfer device 3 for separating the toner from the transfer member 1 and transferring the transfer toner to a transfer sheet; a cleaning device 5 for removing transfer residual toner on the photoconductor 1;
A static eliminator (not shown) for removing the residual charges, a fixing roller 7 and a pressure roller 8 for fixing the toner on the transfer material after the transfer, and a discharge tray 9 for receiving the discharged transfer paper
And so on.

FIG. 2 is an enlarged view of a main part of FIG. The developing device 2 includes a toner hopper 13 serving as a toner replenishing unit for replenishing the toner into the developing unit, stirring members 10 and 11 for stirring the toner supplied from the toner hopper 13, and a developer in the developing unit. And a developing roller 12 for supplying toner to the printer. A developing bias voltage from a power source (not shown) is applied to the developing roller 12, and a predetermined potential is formed between the developing roller 12 and the photosensitive member 1.

In the copying machine of the present embodiment, a reflection type photosensor (hereinafter, referred to as a P sensor) 4 is used as an optical density detecting means for optically detecting the image density on the photosensitive member 1.
Is provided downstream of the developing device 2 in the rotation direction.
Then, the optical density of the reference image formed on the photoconductor is detected at a predetermined timing, and is output as a voltage. The control means determines the remaining amount of toner based on the detection result, and when it is determined that the toner is in an end state, the display panel (not shown) displays the toner end. On the other hand, the toner end is released by detecting the optical density of the background portion of the photoreceptor 1 by the P sensor 4 under control described later, and releasing it when it is detected that the density has increased. Further, the P sensor 4 used in the present embodiment has such a characteristic that the detection voltage decreases as the toner adheres to the photoreceptor 1 and increases as the toner approaches the toner end state. The display of the toner end on the display plate and the release thereof are performed.

FIG. 3 is an explanatory diagram showing the relationship between the toner supply time from the toner hopper 13 into the developing section and the toner supply amount. Immediately after the start of toner replenishment, toner is replenished almost in proportion to the toner replenishment time.
Since the toner in the hopper 13 gradually decreases, the curve becomes a peak as shown in the figure.

FIG. 4 shows a detection voltage (hereinafter referred to as VSG) at the photoconductor background portion detected by the P sensor 4.
FIG. 6 is an explanatory diagram showing a relationship between the toner supply time and the toner supply time. As the toner replenishment time increases, the voltage value detected by the increase in the amount of toner attached to the background portion of the photoreceptor decreases. A in the figure
Indicates a voltage value when the toner is not adhered to the background of the photoconductor in the toner end state, and B in the figure indicates a voltage value at which it is determined that the toner adheres to the background of the photoconductor and the toner is replenished. .

FIG. 5 is an explanatory diagram showing the relationship between the detection voltage VSG and the developer stirring time when the toner supply time is kept constant. C in the figure shows the voltage value at the background portion of the photoconductor when the toner is sufficiently stirred, and D in the figure is
This shows the voltage value at the background portion of the photoconductor immediately after toner supply.
Since the toner charge of the replenished toner increases as the stirring time elapses, the amount of toner attached to the photoconductor 1 gradually decreases as compared to immediately after the toner replenishment. Therefore, the detected voltage value gradually increases based on the above characteristics, and when the toner is sufficiently charged, the amount of adhesion becomes constant, so that the detected voltage value also becomes constant.

The following describes the toner end display canceling process performed by the control unit of the present embodiment. FIG. 8 is a flowchart illustrating a first control example of the toner end release process according to the present embodiment. First, the optical density of the background portion of the photoreceptor is detected by the P sensor 4, and VSG 'is read (S1). Next, it is determined whether or not the detected value VSG 'is in the toner end state (S2). And
If it is determined that it is not the toner end, the process is terminated and a copy is enabled. On the other hand, when it is determined that the toner end is reached, the toner end (TE) is displayed on the display unit of the display means (not shown), and the user opens the front cover of the apparatus main body and inserts a new toner cartridge. The user is prompted to exchange (S3). When the toner cartridge is replaced, the main switch is turned off at the same time as the front cover of the apparatus main body is opened, and the main switch is turned on when the front cover is closed after replacing the toner cartridge (S4). Next, it is determined whether or not the toner end (TE) is stored (S5). If the memory is not stored, the process is terminated and the copying machine is ready for copying. yet,
If so, go to the next step. In the step indicated by S6a, the main motor operates, and the drive system of the photoconductor 1 and the developing device 2 operate. Then, the toner supply motor is driven to supply toner into the developing device 2 (S7). Next, the optical density of the background portion of the photoreceptor is detected by the P sensor 4 to generate a detection voltage (VSG) (S
8). Next, it is determined whether or not VSG is lower than the detection voltage (VSG ') of the photoconductor background portion at the time of toner end (S9). When VSG is higher than VSG ', it is determined that the toner cartridge has not been replaced with a new toner cartridge, and the process returns to step S0. on the other hand,
If VSG is lower than VSG ', it is regarded that the toner cartridge has been replaced with a new toner cartridge, and the toner end display is canceled (S10). T. E. FIG. After the display is cancelled, the driving of the main motor, the photoconductor 1, the developing device 2 and the like is stopped to enter a standby state (S11), and the process is terminated.

According to the above control, the optical density of the background portion of the photoreceptor is detected, and the detected value VSG is compared with the reference optical density detected value VSG 'at the toner end as a reference, thereby displaying the toner end. Judges the conditions for cancellation. For this reason, even if the value of the detected VSG varies due to, for example, the LED of the P sensor 4 being contaminated with toner or the like, the detection value V already detected under the same condition is obtained.
Since this is compared with SG ', this effect does not cause the toner end display to be canceled by mistake, so that the display of the toner end is canceled as compared with the case where the reference value for the toner end cancellation is set in advance. Timing can be controlled accurately.

Also, due to variations in the detected value VSG due to uneven rotation of the photosensitive member 1 or unevenness of the photosensitive member, there may be a case where the VSG is temporarily lowered, that is, it is detected that the optical density of the background portion of the photosensitive member is high. In consideration of this, control may be performed as follows. This variation amount is obtained in advance by an experiment or the like, and after detecting the optical density detection value (VSG ') of the photoconductor background portion at the time of toner end, for example, immediately after step S2, this value is reduced by a certain value. A step of correcting the shift may be added, and the determination in the step S9 may be performed using the corrected value as a reference value. According to this, the value corrected in consideration of the influence of the variation of the detection value VSG is used as the reference value for canceling the toner end, so that the toner end display is canceled even though it is actually in the toner end state. This makes it possible to prevent such a malfunction as to prevent the display from being performed, and to accurately control the timing for canceling the display. It should be noted that even when it is detected that the VSG is high, that is, the optical density of the background portion of the photoreceptor is low, the toner end display may not be canceled even if toner is actually replenished. Although control may be performed in consideration of the above, normally, when replenishing toner, a large amount of toner is replenished at once, so that the optical density of the background does not remain low, and replenishment is performed. By repeating toner supply into the developing device by the above-described control, a slight time lag occurs until the toner is released, but since the toner end release is performed reliably,
The control considered so far may not be required.

FIG. 9 is a flowchart showing a second control example of the toner end releasing process according to this embodiment.
This flowchart is basically the same as FIG.
The steps before S6 to S9 are different. The steps from S1 to S5 and the steps after S9 are the same as those in the above-described embodiment, and a description thereof will be omitted. In step S6 of this control example, when driving the main motor, only the photoconductor motor is driven. Next, the supply motor is driven (S7), and the amount of toner necessary for canceling the toner end display is supplied for H seconds. At this time, the developing motor is still stopped. Then, it is determined whether or not H seconds have elapsed (S7a). If H seconds have not elapsed, the process returns to the step S7 to continue toner supply, and if H seconds have elapsed, the supply motor is stopped (S7b). ). After the completion of the toner replenishment, the developing motor is driven (S7c), and at the same time, the optical density of the background portion of the photoreceptor is detected by the P sensor 4 to generate the detection voltage VSG (S8). The following steps are the same as in the above control example.

FIG. 6 is a timing chart in this control example. In this control example, detection of VSG by the P sensor 4 is performed after driving of the supply motor is completed, and at the same time, the developing motor is driven. The developing motor stops driving when the main motor stops.

According to the above control, since the replenished toner is less stirred, the insufficiently charged toner easily adheres to the background of the photoreceptor, and the VSG decrease becomes remarkable as compared with the first control example. This has the effect of making it easier.

In the flowchart of FIG.
In steps S7 to S7c, the detection timing of the background portion of the photoconductor by the P sensor 4 and the driving timing of the developing motor may be changed as shown in FIG. 7, and the control may be performed based on the flowchart shown in FIG.

FIG. 7 is a timing chart in this control example. In the present control example, the detection by the P sensor 4 is performed after the elapse of I seconds after the driving of the supply motor is started, and the developing motor is also driven at the same time as this detection. Then, the development motor continues to be driven even after the supply motor is stopped, and the drive is stopped together with the stop of the main motor.

FIG. 10 shows a flowchart controlled by the operation timing of FIG. 7. In the step S7d shown in this flowchart, toner is first supplied for I second. This I second is different from the step S7a,
The driving of the developing motor is still stopped. Then, it is determined whether or not I seconds have elapsed. If the I seconds have not elapsed, the developing motor is kept stopped, and when the I seconds have elapsed, the driving of the developing motor is started (S7e). Further, at the same time when the driving of the developing motor is started,
SG is detected (S8). At this time, the supply motor is kept driven. Next, it is determined whether or not VSG is lower than the optical density detection value VSG 'at the time of toner end (S6). If VSG is higher than VSG ', it is regarded that the toner cartridge has not been replaced with a new toner cartridge, and the display of the toner end is kept (S7). On the other hand, if VSG is lower than VSG ', it is considered that the toner cartridge has been replaced with a new toner cartridge, and the toner end display and the toner end memory are canceled (S8). T. E. FIG. After the memory is released, the main motor, the photoconductor unit, the developing unit, and the like are stopped to enter a standby state (S9), and the process is terminated. The following steps are the same as described above.

According to the above control, the rotation of the developing motor is started before the driving of the replenishing motor is completed, and the toner replenished in a concentrated manner in a part of the developing device while the developing motor is stopped is supplied to the stirring members 10 and 11. Developing roller 1 with insufficient agitation by driving
2 and adheres to the background portion of the photoreceptor 1. Therefore, compared to the above-described second control example in which the rotation of the developing motor is started after the driving of the supply motor is completed, the toner is actually There is an advantage that the time until the end display is canceled can be reduced.

As described above, according to the present embodiment, it is not necessary to perform the reference image formation for canceling the toner end display after the toner is replenished, so that the toner consumption can be reduced.

[0032]

According to the image forming apparatus of the present invention, it is determined whether or not the toner has been replenished by determining whether or not the optical density detection value of the background portion of the image carrier after the replenishment of the toner has reached a reference range. Therefore, there is no need to form a reference image to determine whether or not toner has been replenished. Therefore, compared to the related art in which a reference image is formed for determining whether or not toner has been replenished, it is possible to reduce consumption of toner used for purposes other than image formation.

According to the image forming apparatus of the second aspect,
For example, even if the detected values fluctuate due to contamination or deterioration of the optical density detecting means by toner or the like, the reference value detected before toner replenishment and the detection value after toner replenishment are detected. Since the value is detected under the same condition, compared to the case where the reference value is set in advance, for example, even if the display is not canceled due to this effect, the display may be canceled by mistake. No inconvenience. Therefore, the cancellation of the display can be accurately controlled.

According to the image forming apparatus of the third aspect,
Since the value obtained by correcting the detection value after toner replenishment is used as the reference value for canceling the display, it is possible to prevent the display from being accidentally canceled due to the influence of the variation in the detection value. Therefore, the background optical density at the time of toner replenishment can be detected more accurately, and the display can be canceled accurately.

Further, according to the image forming apparatus of the present invention, the driving of the developing device is stopped until the toner supply from the toner container to the developing device is completed, so that the insufficient charging is achieved. If the toner as it is adheres excessively to the background portion of the image carrier, the optical density of the background portion of the image carrier significantly changes before and after toner replenishment, thereby facilitating detection by the detection means. Therefore, the above display can be correctly released.

In particular, according to the image forming apparatus of claim 5,
By delaying the driving of the developing device for the predetermined time, the optical density of the background portion of the image carrier is significantly changed in a short time before and after toner replenishment, and this is detected by the detecting means. Thus, the time from when the toner is supplied to when the display is canceled and when the image forming operation is started can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.

FIG. 2 is an enlarged view of the main part.

FIG. 3 is an explanatory diagram illustrating a relationship between a toner supply time and a toner supply amount.

FIG. 4 is an explanatory diagram illustrating a relationship between a toner supply time and an optical density value of a photoconductor background portion.

FIG. 5 is an explanatory diagram illustrating a relationship between a toner stirring time and an optical density value of a photoconductor background portion.

FIG. 6 is an explanatory diagram showing a timing chart of an image forming process according to the second embodiment.

FIG. 7 is an explanatory diagram showing a timing chart of an image forming process according to a third embodiment.

FIG. 8 is a flowchart illustrating a control example of an image forming process according to the first embodiment.

FIG. 9 is a flowchart illustrating a control example of an image forming process according to the second embodiment.

FIG. 10 is a flowchart illustrating a control example of an image forming process according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing device 3 Transfer device 4 P sensor 5 Cleaning device 6 Charging device 7 Fixing roller 8 Pressure roller 9 Discharge tray 10, 11 Stirring member 12 Developing roller 13 Toner hopper

Continuation of the front page (56) References JP-A-62-299876 (JP, A) JP-A-2-125275 (JP, A) JP-A-5-150646 (JP, A) JP-A-3-184067 (JP) JP-A-1-114879 (JP, A) JP-A-4-127172 (JP, A) JP-A-2-304471 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) G03G 15/08

Claims (5)

(57) [Claims] An image carrier, a developing device for visualizing a latent image formed on the image carrier with a two-component developer comprising a carrier and a toner, and a toner to be replenished in the developing device. A toner container, a toner replenishing device for replenishing toner from the toner container into the developing device, an optical density detecting device for detecting an optical density of the image carrier, and a detection result of the optical density detecting device. Control means for displaying on the display means information indicating that the toner storage section is in a toner shortage state. After displaying the information, the optical density detection means detects the background of the image carrier body. An image forming apparatus, wherein the control unit is configured to execute control for canceling display of the information by the display unit when a detection result of the optical density reaches a predetermined reference value. 2. The optical density of the background portion of the image carrier detected by the optical density detecting means after the display of the information and before the toner replenished in the toner container is replenished into the developing device. Is the release reference value for the above information display,
Based on a comparison result between the release reference value and the optical density of the background portion of the image carrier detected by the optical density detection unit after the toner replenished in the toner storage unit is supplied to the developing device, 2. The image forming apparatus according to claim 1, wherein the control unit is configured to execute control for canceling the display of the information by the display unit. 3. The optical density of the background portion of the image carrier detected by the optical density detecting means after the display of the information and before the toner replenished in the toner container is supplied into the developing device. A value corresponding to an optical density higher than the predetermined density is set as a release reference value for displaying the information, and the release reference value and the optical density after the toner replenished in the toner container is supplied to the developing device. The control unit is configured to execute control for canceling the display of the information by the display unit based on a comparison result with the optical density of the background of the image carrier detected by the detection unit. 2. The image forming apparatus according to claim 1, wherein: 4. A structure in which toner supply operation from the toner container to the developing device and developer stirring operation in the developing device can be performed independently. 4. The image forming apparatus according to claim 1, wherein the control unit is configured to execute control for stopping the operation until the toner replenishment operation is completed. 5. A toner stirring operation in the developing device, wherein the toner supply operation from the toner container to the developing device and the developer stirring operation in the developing device can be performed independently. 4. The image forming apparatus according to claim 1, wherein the control unit is configured to perform control for delaying the operation by a predetermined time from the start of the toner supply operation.