JPH08185039A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device which adds toner to a toner storage part based on display indicating that an amount of remaining toner is insufficient, and then replenishes a developing device with a proper amount of the toner from the toner storage part according to toner concentration obtained when a sign of the insufficiency is displayed. CONSTITUTION: A control means is designed so that time (t) required to replenish the developing device 6 with the toner from the toner hopper 7 is determined based on a ratio between VSG and VSP, in time T required for replenishment operation until the toner concentration obtained when the toner is running out recovers preset toner concentration, wherein VSG is the detection value of the optical density of the base part of a photoreceptor 1 obtained right before the replacement of a toner cartridge 15 and VSP is the detection value of the optical density of a reference image formed on the photoreceptor 1 right before the replacement of the toner cartridge 15.

Description

Detailed Description of the Invention

[0001]

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, a printer, and the like, and more specifically, to an image carrier that forms a latent image and to visualize the latent image on the image carrier. A developing device, a stirring member that stirs the developer stored in the developing device of the developing device, and a toner storage portion that stores the toner to be supplied into the developing device. Image forming means for forming a reference image, an optical density detecting means for detecting an optical density of the reference image and an optical density of a background portion of the image carrier, and an inside of the toner containing portion for detecting an amount of toner in the toner containing portion. Based on the detection result of the toner remaining amount detecting means provided in
To display a toner remaining amount shortage, and to replenish the toner accommodating portion with toner based on the display by the display device, and then to restore the toner density in the developing device to the normal image forming state. The present invention relates to an image forming apparatus provided with a control means for performing a toner forced replenishment operation consisting of toner replenishment from the toner storage portion into the developing device and developer agitation in the developing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, an electrostatic latent image formed on an image carrier is visualized with toner in a developer, and 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 density in the developing device in order to form a good image. For this reason, for example, a toner density detecting device for detecting the toner density provided in the developing device, or an optical density of a reference image formed on the image carrier, which is provided at a position facing the image carrier, is detected. There is known an image forming apparatus in which the optical density detecting means detects the toner density during the image forming operation, and replenishes the toner according to the change of the detection signal to control the toner density (for example, JP-A-63-63). No. 253975, Actual Kaihei 2-
24859). Then, when the toner in the toner container is exhausted, the toner cannot be supplied into the developing device,
Since the toner density in the developing device gradually decreases, when the toner density becomes lower than a predetermined density, display that the remaining amount of toner is insufficient (hereinafter referred to as toner end) Is also known. Further, in Japanese Patent Laid-Open No. 63-253975, after the user sets a toner container filled with toner based on the indication of the toner end, toner is replenished from the toner container into the toner container, and A mode is set to force toner replenishment from the toner storage unit to the developing unit, and regardless of the toner concentration at the toner end, the amount of toner replenished in advance is determined by the replenishment amount per unit time and the replenishment time. It is also disclosed to do so.

[0003]

However, according to this configuration, since the toner replenishment amount or the toner replenishment time is determined regardless of the image density immediately before the toner end or the toner concentration, the toner container is replaced. Even if the toner is forcibly replenished with the toner, if the predetermined replenishment amount is less than the required amount or the toner replenishment time is short, the toner concentration will not reach the desired concentration. Was low, and the toner end was displayed again, which was a problem.

The present invention has been made in view of the above problems, and it is an object of the present invention to determine the toner density at the time of the forced toner replenishment operation after the toner replenishment based on the display of the toner remaining amount shortage. Accordingly, it is an object of the present invention to provide an image forming apparatus capable of supplying an appropriate amount of toner into a developing device.

[0005]

To achieve the above object, an image forming apparatus according to a first aspect of the present invention comprises an image carrier for forming a latent image, and a developing device for visualizing the latent image on the image carrier. A stirring member for stirring the developer contained in the developing device of the developing device, and a toner containing portion containing the toner to be supplied into the developing device, and a reference image is formed on the image carrier. A reference image forming means, an optical density detecting means for detecting the optical density of the reference image and the optical density of the background portion of the image carrier, and an internal device for detecting the amount of toner in the toner containing portion. The toner remaining amount detecting means, a display means for displaying the toner remaining amount shortage based on the detection result by the toner remaining amount detecting means, and after replenishing the toner in the toner containing portion based on the display by the displaying means. , The toner density in the developing unit is In order to restore the state at the time of formation,
In an image forming apparatus having a control unit for performing a toner forced replenishment operation consisting of toner replenishment from the toner storage unit into the developing unit and developer agitation in the development unit, after replenishing the toner storage unit When the optical density detection value of the background portion detected by the optical density detection means before the toner of (1) is replenished to the developing device is VSG and the optical density detection value of the reference image at this time is VSP, The toner replenishment time t during the preset execution time T of the forced toner replenishment operation is determined by the value of the ratio of VSG and VSP.
It is characterized in that the control means is configured.

Particularly, in the image forming apparatus of claim 2, in the image forming apparatus of claim 1, the stirring speed of the stirring member is changed in accordance with the toner replenishment amount replenished within the execution time T. It is a feature.

An image forming apparatus according to a third aspect is housed in an image carrier that forms a latent image, a developing device that visualizes the latent image of the image carrier, and a developing device of the developing device. A reference image forming means for forming a reference image on the image carrier, and an optical member for the reference image. An optical density detecting means for detecting the density and the optical density of the background portion of the image carrier, a toner remaining amount detecting means provided in the toner containing portion for detecting the amount of toner in the toner containing portion, and the toner remaining amount. Display means for displaying a toner remaining amount shortage based on the detection result by the amount detection means, and after replenishing the toner in the toner containing portion based on the display by the display means,
Forced toner replenishment operation consisting of toner replenishment from the toner storage unit into the developing unit and developer agitation in the developing unit in order to restore the toner concentration in the developing unit to the state at the time of normal image formation. In the image forming apparatus provided with a control means for performing the above, the optical density detection value of the background portion before the toner replenished in the toner storage portion is replenished to the developing device is VSG, and the reference value at this time is VSG. The optical density detection value of the image is VSP
And the execution time T of the toner forced replenishment operation is VSG
It is characterized in that the control means is configured so as to be determined by the value of the ratio between VSP and VSP.

In particular, an image forming apparatus according to a fourth aspect is the image forming apparatus according to the third aspect, wherein an upper limit is set for the execution time T.

In particular, an image forming apparatus according to a fifth aspect is characterized in that, in the image forming apparatus according to the third or fourth aspect, the display means is configured to display the execution time T.

[0010]

In the image forming apparatus according to the present invention, the execution time T for performing the toner forced replenishment operation consisting of toner replenishment from the toner container to the developing device and developer agitation in the developing device is set in advance. Every time, after the toner is replenished to the toner storage portion, the optical density of the background portion of the image carrier before being replenished to the developing device and the optical density of the reference image formed on the image carrier are detected by the optical density detecting means. To do. Then, by the calculation of the control means, the toner replenishment time t corresponding to the toner amount to be replenished is determined from the ratio of these detection values, and replenishment is performed within the execution time T.

Particularly, in the image forming apparatus according to the second aspect, according to the amount of toner replenished within the execution time T,
The stirring speed of the stirring member is changed so as to increase as the amount of toner increases. As a result, sufficient stirring is performed to charge the toner according to the amount of replenished toner, and insufficient charging does not occur.

Further, in the image forming apparatus of the third aspect, after the toner is replenished to the toner containing portion and before the toner is replenished in the developing device, the optical density of the background portion of the image bearing body and the image formed on the image bearing body. The optical density of the reference image is detected by the optical density detecting means. Then, the execution time T for performing the toner forced supply operation is calculated by the calculation of the control means by calculating the ratio of these detection values, and the toner forced supply operation is executed based on the execution time T. .

Particularly, in the image forming apparatus of the fourth aspect, since the execution time T has an upper limit, the toner replenishing operation is not performed for a time longer than the upper limit, and the execution is performed due to some abnormality, for example. Even when the value of VSP / VSG is such that the time T becomes long, it is possible to prevent the toner from being replenished into the developing device in excess of the toner amount corresponding to the upper limit time.

Particularly, in the image forming apparatus according to the fifth aspect, the execution time T is displayed by the display means to notify the user of the time until the forced toner supply operation is completed. The display time may be displayed so as to be counted down as time passes.

[0015]

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) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a copying machine using a two-component developer according to the present embodiment, and FIG. 2 is a diagram of FIG. 1 seen from above. By the charging charger 3, an electrostatic latent image is formed by the exposure 4 on the photoconductor 1 as an image carrier that has already been uniformly charged. The electrostatic latent image is developed by the toner in the developing device 6 of the developing device provided on the right side of the photoconductor 1, and the developed image is transferred to a transfer sheet conveyed from a sheet feeding device (not shown). It is transferred by the charger 11 and separated from the photoconductor 1. Then, the separated transfer paper is discharged to the outside of the machine through a fixing device (not shown).
On the other hand, after the transfer, the photoconductor 1 is cleaned by a cleaning device 12 provided on the left side of the drawing to remove the residual toner, and then the charge removal lamp 2 removes the residual charge, and the charging charger 3 charges the photoconductor 1 uniformly. To prepare for the next image formation.

The developing device is mainly composed of a developing device 6 and a toner hopper 7 provided above the developing device 6 as a toner accommodating portion. The developing device 6 has a developing roller 8 provided in a casing opening facing the photoconductor 1 and a stirring paddle 9 as a developer stirring member at the bottom of the casing. Then, the two-component developer including the toner and the carrier is mixed and stirred by the stirring paddle 9 while being stirred.
Replenishing on top. On the other hand, the toner hopper 7 has a toner amount detection sensor 10 composed of a piezoelectric sensor or the like at the bottom,
A toner replenishment port 16 for replenishing new toner from the toner cartridge 15 into the toner hopper 7 when the toner amount detection sensor 10 detects that the toner is exhausted is provided at the upper part of the toner hopper 7 ( See FIG. 2). Further, the toner discharge portion to the lower developing device 6 has a toner replenishing roller 13 rotatably driven by a motor (not shown). Further, a photo sensor (hereinafter referred to as a P sensor) as an optical density detecting unit for detecting the optical density of the photoconductor 1 at a position facing the surface of the photoconductor 1 on the downstream side of the developing device 6 in the rotation direction of the photoconductor 1. 1)
4 is provided, and the P sensor 14 is composed of a light emitting element that emits light toward the surface of the photoconductor 1 and a light receiving element that receives the light reflected by the surface. And
The detection by the P sensor 14 is performed at a predetermined timing, and based on the detection result, the toner replenishing roller 13 is rotationally driven by the control means (not shown) to replenish the toner from the toner hopper 7 to the developing device 6.

Further, when the toner amount detection sensor 10 detects that the amount of toner is less than the predetermined amount, the toner end is displayed on the display portion of the display means (not shown). Then, based on this display, the toner cartridge 15 is replaced with a new one for the user or the like.

Next, the toner density control during the image forming operation will be described. In the toner density control of the present embodiment, the P sensor 14 having a characteristic that the output becomes smaller as the image density becomes higher is used, and by utilizing this characteristic, the output VSG of the P sensor 14 detected at a predetermined timing. ,
The density of the reference image formed on the photoconductor 1 corresponding to a predetermined reference pattern is compared with the output value VSP, the amount of toner to be replenished is determined according to this ratio, and the required amount is set to the toner hopper 7. Is being replenished to the developing device 6. (Hereinafter, margin)

Hereinafter, an example of controlling the toner density related to the forced toner supply operation after the toner cartridge 15 is replaced based on the toner end display will be described. [Control Example 1] In the present embodiment, the time (hereinafter referred to as toner concentration recovery operation time) T until the toner concentration in the developing device is restored to the toner concentration during normal image formation by the forced toner replenishment operation is constant. The control at the time of toner end and at the time of replacement of the toner cartridge 15 in the above case will be described with reference to the flowchart shown in FIG. FIG.
Further, the toner amount detection sensor indicated by reference numeral 10 in FIG. 2 detects the toner end during copying, and the toner near end is turned on (S1). In this embodiment, as the toner near-end condition, a toner amount of about 50 copies remains until the toner end, and the toner near-end is turned on when this state is reached. Is set to. And after the 50th copy,
A pattern is created on the photoconductor 1 and read by the P sensor 14 to detect the optical density detection value VSP of the pattern portion at the toner end and the optical density detection value V of the background portion at the toner end.
The ratio to SG, that is, VSP / VSG is stored (S2).
Note that this memory can determine the toner replenishment amount for each copy, but in order to reduce the consumption amount of toner used for pattern formation on the photoconductor 1 as much as possible, it is performed for each copy to some extent. Is more effective. And VSP
When / VSG is stored in memory, it is determined that the toner end state is reached, and the apparatus is stopped (S3). Next, the toner density recovery operation will be described. Here, in this control example, the toner concentration recovery operation is set to the predetermined time T in advance. Further, as shown in the timing chart of FIG. 4, the toner concentration recovery operation has one pattern of toner replenishment ON (forced replenishment and agitation operation) and OFF (operation of only agitation). Is the total time to repeat this pattern. When the time for turning on the toner replenishing motor (not shown) for driving the toner replenishing roller 13 is set to t, VSP / VSG of the toner is supplied based on the relationship between VSP / VSG and toner replenishing time t as shown in FIG. The toner replenishment time t corresponding to the value is determined (S4). Then, the user opens the front door of the apparatus main body based on the lighting display of the toner near end and replaces the toner cartridge 15. Then, after replacing the cartridge 15, the front door is closed, and at the same time, the toner concentration recovery operation for a certain time T is performed to replenish toner from the cartridge 15 to the toner hopper 7 and forcibly replenish toner from the toner hopper 7 to the developing device 6 (S5). . During this fixed time T, the stirring paddle 9 is kept ON all the time. Then, when the fixed time T has passed, the toner concentration recovery operation is ended (S6). In consideration of the fact that stirring cannot catch up with the amount of toner to be replenished, based on the relationship shown in FIG.
The rotation speed of the stirring paddle 9 may be controlled to be changed according to the toner replenishment time t. In this figure, the stirring paddle 9
The rotational speed of the stirring paddle 9 has a certain lower limit because the minimum toner replenishment time t is required to release the toner end. On the other hand, since the rotation speed of the motor that drives the stirring paddle 9 is also limited, the rotation speed of the stirring paddle 9 also has an upper limit value.

According to the above control example, when the time T until the toner density recovery is determined in advance, the optical density of the toner adhering to the background portion of the photosensitive member before the toner cartridge 15 is replaced at the toner end is determined in advance. By determining the toner replenishment time t within the set toner concentration recovery time T, it is possible to replenish the toner amount according to the toner concentration at the toner end, and the optical density detection value VSG of the background and the reference Image optical density detection value V
By taking the ratio with SP, the amount of toner to be replenished can be accurately calculated even when the surface of the P sensor 14 is soiled with toner or the like. Furthermore, when changing the stirring speed of the stirring paddle 9 according to the toner supply amount,
Even if the toner supply amount is large, sufficient agitation is performed, so that the toner is surely charged and the background stain on the image and the toner scattering can be prevented.

[Control Example 2] The basic flow of this control example is as follows.
3 is the same as the flow chart shown in FIG. 3 of the control example 1, except that in the step S4 shown in FIG.
The difference is that the toner concentration recovery operation time T is changed according to the value of SG. FIG. 7 is a graph showing the relationship between VSP / VSG and the toner concentration recovery operation time T.
In the figure, when VSP / VSG is 0.1, the toner density is high at the toner end, and when it is 0.3, the toner density is low. Here, when VSP / VSG is lower than 0.1 and higher than 0.3, the operating time T has an upper limit value and a lower limit value, respectively.
Even if VSP / VSG is lower than 0.1 and the toner concentration is high, the toner end indication is displayed and a certain amount of toner replenishment is required. On the other hand, even if VSP / VSG is higher than 0.3 and the toner concentration is low, if VSP / VSG shows a high value due to some abnormality, an excessive amount of toner than the actually required toner amount is used. As a result, the toner concentration in the developer rises, and the charge becomes insufficient,
As a result, background stains and toner scattering on the image may occur. Therefore, in order to prevent such a problem, an upper limit value is set for the operation time T. FIG. 8 is a timing chart showing the toner replenishment time t in the toner concentration recovery operation time T determined based on the relationship shown in FIG. 8 also has one pattern of toner supply ON (forced supply and agitation operation) and OFF (operation of only agitation) as in FIG. 4, and the toner concentration recovery operation time T is set by repeating this pattern. It has become the total time. During the fixed time T, the stirring paddle 9 is used as in FIG.
Is always on.

According to the above control example, the toner density at the toner end is obtained by detecting the optical density of the toner adhering to the photosensitive member before the toner cartridge 15 is replaced. Therefore, the toner density corresponding to this optical density is obtained. By determining the density recovery time T, it is possible to perform control such that an amount of toner corresponding to the toner density at the toner end is replenished into the developing device. Further, even if the surface of the optical density detecting means is contaminated and the optical density detection value at this time is lowered, the detection value VSG of the optical density of the background portion and the detection value VSP of the optical density of the pattern portion are obtained. Therefore, the influence can be canceled out, and the toner concentration recovery time T
Never make a mistake. Also, the toner supply time t
By setting the upper limit of the above, even if an output abnormality occurs due to, for example, a sensor abnormality, excessive toner is not replenished into the developing device 6. Therefore, it is possible to prevent the background stain of the image due to the toner with insufficient stirring and the toner scattering. Furthermore, by displaying the toner concentration recovery time T, the user can effectively use the time during operation until the toner concentration is recovered.

[0023]

According to the image forming apparatus of the present invention, before the toner is replenished from the toner container to the developing device, the execution time T of the forced toner replenishment operation is determined by the detection value detected by the optical density detecting means. Toner replenishment time t is determined and toner corresponding to the insufficient toner amount is replenished, so that toner replenishment and the toner concentration in the developing device after replenishment can be stabilized and a predetermined image density can be secured. can do. Further, the toner replenishment time t is determined by taking the ratio of the optical density detection value VSG of the background portion of the image carrier and the optical density detection value VSP of the reference image formed on the image carrier. Even when the surface of the density detecting means is soiled, the replenishment time t is not erroneously determined, and there is a problem such as toner scattering due to excessive toner replenishment and re-toner end display due to insufficient replenishment. It has an excellent effect that it can be prevented.

Particularly, according to the image forming apparatus of claim 2,
Depending on the amount of toner replenished within the execution time T, the stirring speed of the stirring member is changed so as to increase as the amount of toner increases, so even if the amount of replenished toner increases, it takes a long time. As sufficient agitation is achieved without the need,
Insufficient charging does not occur. Therefore, it is possible to more effectively prevent defects such as background stains on the image and toner scattering.

Particularly, according to the image forming apparatus of claim 4,
By setting the upper limit to the execution time T, the toner replenishing operation is not performed for a time longer than the upper limit, so that it is possible to prevent the toner replenishment from being performed in excess of the amount actually required. Therefore, it is possible to prevent the background stain of the image and the toner scattering due to insufficient stirring of the supplied toner.

Particularly, according to the image forming apparatus of claim 5,
By displaying the execution time T, the time until the end of the operation can be easily grasped, so that the user can effectively use this time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic copying machine according to an embodiment.

FIG. 2 is a plan view showing the outline of the copying machine.

FIG. 3 is a flowchart showing toner density control after toner end according to the embodiment.

FIG. 4 is a timing chart showing a toner replenishment time t within a toner concentration recovery time T according to control example 1.

FIG. 5: Ratio VSP / VSG of values detected by P sensor
FIG. 4 is an explanatory diagram showing a relationship between the toner replenishment time t.

FIG. 6 is an explanatory diagram showing a relationship between a toner replenishment time t and a rotation speed of a stirring paddle.

FIG. 7: Ratio VSP / VSG of values detected by P sensor
FIG. 5 is an explanatory diagram showing the relationship between the toner concentration recovery time T.

FIG. 8 is a timing chart showing a toner replenishment time t within a toner concentration recovery time T according to control example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Elimination lamp 3 Charging charger 4 Exposure 5 Eraser 6 Developer 7 Toner hopper 8 Developing roller 9 Stirring paddle 10 Toner amount detection sensor 11 Transfer device 12 Cleaning device 13 Toner supply roller 14 P sensor 15 Toner cartridge 16 Toner supply port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01N 21/47 F G03G 21/14

Claims (5)

[Claims] 1. An image carrier that forms a latent image, a developing device that visualizes the latent image on the image carrier, and a stirring member that stirs a developer contained in a developing device of the developing device. A reference image forming means for forming a reference image on the image carrier, and a toner containing part for containing toner to be supplied into the developing device; and an optical density of the reference image and a background part of the image carrier. Optical density detecting means for detecting the optical density of the toner, a toner remaining amount detecting means provided in the toner containing portion for detecting the toner amount in the toner containing portion, and a detection result by the toner remaining amount detecting means, Display means for displaying the toner remaining amount shortage,
After the toner is replenished to the toner accommodating portion based on the display by the display means, in order to restore the toner concentration in the developing device to the state at the time of normal image formation, the toner is moved from the toner accommodating part into the developing device. In the image forming apparatus having the control means for performing the forced toner replenishment operation consisting of the toner replenishment and the developer agitation in the developing device, the replenished toner is replenished to the developing device. When the optical density detection value of the background portion detected by the optical density detection means is VSG and the optical density detection value of the reference image at this time is VSP, the preset toner forced supply operation is executed. An image forming apparatus characterized in that the control means is configured so that the toner supply time t during the time T is determined by the value of the ratio of VSG and VSP. 2. The image forming apparatus according to claim 1, wherein the stirring speed of the stirring member is changed in accordance with the toner replenishment amount replenished within the execution time T. 3. An image carrier that forms a latent image, a developing device that visualizes the latent image on the image carrier, and a stirring member that stirs the developer contained in the developing device of the developing device. A reference image forming means for forming a reference image on the image carrier, and a toner containing part for containing toner to be supplied into the developing device; and an optical density of the reference image and a background part of the image carrier. Optical density detecting means for detecting the optical density of the toner, a toner remaining amount detecting means provided in the toner containing portion for detecting the toner amount in the toner containing portion, and a detection result by the toner remaining amount detecting means, Display means for displaying the toner remaining amount shortage,
After the toner is replenished to the toner accommodating portion based on the display by the display means, in order to restore the toner concentration in the developing device to the state at the time of normal image formation, the toner is moved from the toner accommodating part into the developing device. In the image forming apparatus having the control means for performing the forced toner replenishment operation consisting of the toner replenishment and the developer agitation in the developing device, the replenished toner is replenished to the developing device. When the optical density detection value of the background portion before is VSG and the optical density detection value of the reference image at this time is VSP,
An image forming apparatus characterized in that the control means is configured so that the execution time T of the forced toner supply operation is determined by the value of the ratio of VSG and VSP. 4. The image forming apparatus according to claim 3, wherein the execution time T has an upper limit. 5. The image forming apparatus according to claim 3, wherein the display means is configured to display the execution time T.