JPH06230670A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a copying machine capable of supplying a proper amount of toner which does not cause excessive increase in toner concentration even when a minimum amount of toner supplied for one copy is large. CONSTITUTION:After five copies are taken, a reference toner image is formed on a photosensitive drum 20, and the image density of the reference toner image is detected by a P sensor. According to the detection value, the number of times that toner is supplied for another five copies is set. At the time of taking each copy, the toner is supplied to a development part 42 from a hopper part 40 only the set number of times. The number of times that the toner is supplied may be set according to a transfer paper size or an image area rate. The toner supply may also be carried out by correcting the set number of times according to the transfer paper size and the image area rate each time a copy is taken.

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 a developing section in which a developer carrier is provided and a toner to be supplied to the developing section. The present invention relates to an image forming apparatus including a developing device having a toner storage unit for storing toner and a toner replenishing unit that replenishes toner from the toner storage unit to the developing unit.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for replenishing toner from a toner accommodating portion of a developing device to a developing portion provided with a developer carrying member or the like has a toner replenishing means depending on a required toner replenishing amount. ON / OF the replenishment clutch or replenishment solenoid for transmitting the rotational driving force to the replenishment roller.
It is known that F is used to change the supply time.

[0003]

However, as shown in FIG.
In an image forming apparatus equipped with a DTM (Developer Toner Magazine) type developing device in which a toner and a carrier which are two-component developers are formed into a magazine as shown in FIG. Is rotated, and the tip of the agitator is moved so as to strike on the boundary between the toner storage section and the developing section,
Toner is replenished from the toner containing portion to the developing portion through a replenishing hole formed at the boundary portion. When an agitator having two arms as shown in FIG. 3 (a) is provided, a replenishment clutch or a replenishment solenoid provided between the agitator and its drive unit in order to replenish the toner. At least for the time when the agitator rotates half a turn
Since the number of rotations of the agitator during one copy is usually set to about 3 to 4 rotations, the number of times of toner replenishment during one copy is only about 6 to 8 times.

Therefore, if the minimum replenishment amount of toner replenishment per one toner replenishment performed during one copy is set to the same amount as the minimum replenishment amount in the conventional developing device,
The maximum replenishment amount of toner replenishment per replenishment performed during one copy is only about 6 to 8 times the minimum replenishment amount. This maximum replenishment amount is considerably smaller than the maximum replenishment amount in the conventional developing device (about 40 times the minimum replenishment amount). The maximum replenishment amount in the DTM type developing device is
In order to set the same amount as the maximum replenishing amount in the conventional developing device, the minimum replenishing amount must be set to be considerably larger than the minimum replenishing amount in the conventional developing device, for example, about 5 times. However, if the toner replenishment is controlled for each copy with the minimum replenishment amount set high,
There is a fear that the toner density in the developing section excessively rises, the toner becomes excessive, and the image has background stains.

Therefore, it is possible to increase the number of toner replenishments by increasing the number of revolutions of the agitator by reducing the amount of toner replenishment per toner replenishment during one copy. This is impossible in reality because the ratio must be reduced and a large driving torque is required.

The present invention has been made in view of the above problems, and an object thereof is to prevent an excessive toner concentration increase even when the minimum replenishment amount per image forming operation is large.
An object of the present invention is to provide an image forming apparatus that can appropriately supply toner.

[0007]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention accommodates a developing section in which a developer carrying member is arranged and a toner to be replenished to the developing section. In an image forming apparatus including a developing device having a toner containing portion and a toner replenishing means for replenishing toner from the toner containing portion to the developing portion, the image forming operation is performed a predetermined number of times.
As a unit, a control means for controlling the amount of toner replenished by the toner replenishing means is provided.

According to another aspect of the image forming apparatus of the present invention, a developing section in which a developer carrying member is arranged, a toner containing section for containing toner to be replenished to the developing section, and the toner containing section to the developing section. In an image forming apparatus including a developing device having a toner replenishing means for replenishing toner to the toner, and a manual transfer material supplying means for manually supplying a transfer material, the toner is set in units of a plurality of predetermined image forming operations. It is characterized in that control means for controlling the amount of toner replenished by the replenishing means is provided.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the control means is based on the size of the transfer material and / or the image area ratio of the original.
It is characterized in that the toner supply amount is controlled.

[0010]

According to the image forming apparatus of claim 1 or 2,
Rather than toner replenishment control that replenishes toner only during one image forming operation, the toner replenishing amount is controlled by the toner replenishing means in units of a predetermined plurality of image forming operations. For example, the amount of toner replenishment during each image forming operation is controlled with the image forming operation of 5 to 10 times as one unit. As a result, the toner replenishment amount per image forming operation is limited, and accordingly, the image having the developing device in which the minimum replenishment amount per image forming operation is set high in order to achieve a predetermined maximum replenishment amount Even in the forming apparatus, since the higher minimum replenishment amount is replenished for the predetermined plurality of image forming operations, the toner concentration in the developing unit does not excessively increase.

According to another aspect of the image forming apparatus of the present invention, the transfer material size and / or the original image area ratio are corrected by correcting the toner supply amount based on the size of the transfer material and / or the original image area ratio of the original. The toner is appropriately replenished in accordance with the variation in the toner density of the developing unit caused by the difference of Further, the toner replenishment amount in each image forming operation in a predetermined plurality of image forming operations, which is one unit, is defined as the transfer material size in each image forming operation or in the image forming operation immediately before the image forming operation, and / or the image. It is also possible to correct the toner based on the area ratio and replenish the toner. As a result, in an image forming apparatus in which the size and / or the image area ratio of the transfer material often differs for each image forming operation, such as when the transfer material is supplied by hand, the size of the transfer material and / or the image area ratio of the original document. Further, more appropriate toner replenishment is performed according to the variation of the toner density of the developing portion due to the change of.

[0012]

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. First, an outline of the entire copying machine will be described. FIG. 2 is a front view showing a schematic configuration of the copying machine according to this embodiment. A contact glass 10 for placing an original is provided on the upper part of the copying machine, and an openable / closable original cover 11 is attached so as to cover the contact glass 10. Below the contact glass 10, a document irradiation lamp 12, a reflection mirror 13,
An optical unit as an exposure unit including the moving lens system 14 and the like is provided. The photoconductor drum 20 is arranged at a position where the imaging light from the optical unit is irradiated. The photosensitive drum 20 is rotated clockwise by a driving system (not shown). Around the photoconductor drum 20, the charging charger 21,
An eraser 22, a developing unit 23 as a developing device,
Transfer charger 24, separation charger 25, separation claw 2
6, a cleaning unit 27, a static elimination lamp 28, etc. are provided.

The developing unit 23 is a DTM (developer toner magazine) type developing device in which toner and carrier are formed into a magazine, and as shown in FIG. 3A, serves as a toner containing portion for containing toner. Hopper portion 40 and developing sleeve 41 as a developer carrying member
And the like, and the developing section 42 rotatably provided. The both sections 40, 42 are integrated by, for example, screwing.
In the casing 40a of the hopper 40, an agitator 43 having an agitator mylar 43a attached to the tip thereof is provided as a toner replenishing means. In addition, the hopper unit 4 is provided in the casing 42a of the developing unit 42.
Mixing roller 44 for mixing the toner replenished from 0 into the developer consisting of the carrier and the toner, and the developing sleeve 4 while stirring the developer from the mixing roller 44.
1, a stirring paddle 45 to be supplied to the No. 1, a developing doctor 46 that regulates the amount of the developer on the developing sleeve 41, a separator 47 that recirculates the developer regulated by the developing doctor 46 onto the mixing roller 44, and the like. .

Then, from the mounting portion A of the paper feed cassette (not shown) formed on the right side surface of the copying machine, the photosensitive drum 2
The transfer path of the transfer paper (not shown) as a transfer material, which passes through the lower facing portion of 0 and reaches the paper discharge section B formed on the left side of the copying machine, is a paper feed roller 30, a delivery roller pair 31, and a resist. The roller pair 32, the conveyance belt device 33, the fixing roller pair 34, the paper discharge roller pair 35, and the like are included. Further, a manual paper feed tray 36 as a manual transfer material supplying means is attached to the right side surface of the copying machine so as to be rotatable about a rotation axis C. When the paper is not manually fed, the tip of the manual paper feed tray 36 is fixed to a fixing member 36a composed of a magnet or the like, and is accommodated in the right side surface of the copying machine. On the other hand, when manual feeding is performed, the transfer paper is fed onto the manual feeding tray 36 while being tilted while rotating in the direction of the right arrow about the rotation axis C.

In the above structure, the contact glass 1
When a document is set on the document 0 and the copy start button of the operation unit (not shown) is pressed, the document irradiation lamp 12 irradiates the document with the emitted light, and the reflected light passes through the reflection mirror 13, the moving lens system 14, and the like. An image is formed on the photosensitive drum 20. The surface of the photoconductor drum 20 is uniformly charged by the charging charger 21, and this charge is selectively erased by the reflected light from the document to form an electrostatic latent image. Then, the eraser 22 erases charges around the image area, and the rotation of the photosensitive drum 20 causes the developing unit 23 to rotate.
Pass through the opposite part of. At this time, the electrostatic latent image is visualized by the developing unit 23 having the developing sleeve 41 to which a predetermined developing vice voltage is applied, and the photosensitive drum 20 is exposed.
A toner image is formed on top. This toner image is the paper feed roller 3
0 and the feed roller pair 31 feeds paper from a paper feed cassette (not shown), and the registration roller pair 32
Is transferred by the transfer charger 24 onto the transfer paper conveyed to the surface of the photoconductor drum 20 at a timing. The transfer paper on which the toner image has been transferred is neutralized by the separation charger 24, separated from the surface of the photoconductor drum 20 with the assistance of the separation claw 26 as necessary, and sent to the fixing roller pair 34 by the conveyor belt device 33. To be Then, the toner image is fixed on the transfer sheet by the fixing roller pair 34, and is discharged onto a sheet discharge tray (not shown) of the sheet discharge section B by the sheet discharge roller pair 35. On the other hand, on the surface of the photosensitive drum 20 after the toner image is transferred to the transfer paper, the residual toner is removed by the cleaning unit 27 after the residual toner is removed, and the residual charge is removed to prepare for the next image formation. .

Further, as shown in FIGS. 3A and 3B, in the developing unit 23, the replenishment clutch 48 is provided.
Is turned on at a predetermined timing, the driving force is transmitted from the gear 49a of the rotary drive unit to the gear 43b via the gear 49b, and the agitator 43 in the hopper unit 40 rotates. With the rotation of the agitator 43, the agitator 43
The agitator mylar 43a attached to the tips of the two arm portions of the above-mentioned moves to tap on the boundary portion 50 between the hopper portion 40 and the developing portion 42, and the replenishment hole formed in the boundary portion 50 ( Toner is replenished to the developing unit 42 from (not shown).

Next, the toner replenishment control in this embodiment will be described. In this embodiment, when the copy of the predetermined reference copy number a ₀ is completed, a reference toner image that is a reference visible image with respect to the reference pattern having a predetermined image density is formed on the photosensitive drum 20, and the reference toner image of the reference toner image is formed. The image density is a light reflection type density sensor 1 (hereinafter, referred to as P
Sensor), and based on the detected value Vsp, the number of times toner is replenished during the subsequent copying of the predetermined number of copies a ₀ is set, and the developing unit 4 of the developing unit 23 is set.
The toner replenishment control is performed so that the toner density of No. 2 is constant.

The reference toner image is the charging charger 21.
The photoconductor drum 20 is charged to a predetermined potential by the eraser 22, and the eraser 22 makes the photosensitive drum 20 have a predetermined size.
By developing with No. 3, it can be formed on the photoconductor drum 20. The P sensor 1 measures the intensity of reflected light when it is irradiated with light of a predetermined intensity,
The density of the reference toner image formed on the photoconductor drum 20 is detected. The P sensor 1 detects not only the density of the reference toner image but also the density of the background portion on the photoconductor drum 20. For the toner density control, the ratio η (= Vsp / Vsg) between the detected value Vsp with respect to the density of the reference toner image of the P sensor 1 and the detected value Vsg with respect to the density of the background portion is used.

The toner replenishing control means according to this embodiment is
As shown in FIG. 4, basically the CP as the main control unit 2
A U2a, a RAM 2b as a storage unit, a ROM 2c, and an I / O unit 2d as an input / output unit. The main control unit 2 has a P sensor 1, a replenishing clutch 48, and a charging charger 21 via the I / O unit 2d. , Eraser 22, developing unit 23, etc. are connected, P sensor 1, replenishment clutch 48
It is configured to be able to control ON / OFF of each of the above.

FIG. 1 shows a flow chart of a toner replenishment control program written in the RAM 2b or ROM 2c. First, when the normal image forming operation for one sheet is completed (step 1), 1 is added to the value of the variable a corresponding to the number of copies of the control means 2 (step 2),
It is determined whether or not the value of the variable a has reached the reference copy number a ₀ (step 3). The reference copy number a ₀ is set to 5, for example. When the value of the variable a for the number of copies reaches the reference number of copies a ₀ , the P sensor 1 is turned on.
Then, the developing bias voltage, the charging charger 21, and the transfer charger 24 are set and changed to outputs for the P sensor (step 4), and the photosensitive drum 20 is charged to a predetermined potential. Next, the eraser 22 is turned on / off in accordance with the P sensor pattern area to form an electrostatic latent image of the P sensor pattern of a predetermined size on the photoconductor drum 20, and this electrostatic latent image is developed. Development is performed by the unit 23 to form a toner image of the P sensor pattern (step 5). To prevent the toner image of the P sensor pattern from being transferred onto the transfer paper,
The transfer charger 24 is set to the output for the P sensor (0 or the same polarity output as the toner). Next, the image density of the toner image of the P sensor pattern and the image density of the background portion are detected by the P sensor 1, and the respective detected values are set as Vsp and Vsg and are input to the control means 2 (step 6). Next, the CPU 2a of the control means 2 calculates the ratio Vsp / Vsg of Vsp and Vsg and inputs the calculated value into the variable η (step 7). Next, the value of the variable η is converted into the value of the P sensor level divided into a predetermined number of levels (step 8). Next, based on the value of the P sensor level and the like, the number of times of toner replenishment during copying of the number of copies a ₀ until the next P sensor is detected is set. That is, the number of copies to be supplied with toner is set (step 9). Next, the toner supply operation is controlled based on the set number of times of toner supply (step 10). Next, the variable a corresponding to the number of copies
Whether the value of has become a ₀ (step 1
1). When the variable a for the number of copies reaches a ₀ , the initial value 0 is input to the variable a and stored in the RAM 12a (step 12), and the end sequence of the image forming operation is executed (step 13).

The reference copy number a ₀ is set to 5 here. If the set value of the reference copy number a ₀ is increased, the toner replenishment level can be subdivided, but the reading interval by the P sensor 1 becomes large, so that it corresponds to a rapid toner density change in the developing unit 42. On the other hand, if the set value of the reference copy number a ₀ is decreased, the change in the toner density can be dealt with quickly, but the toner replenishment amount per time must be set large. The change in the toner density inside becomes large, and the background stain of the image easily occurs. Therefore, it is necessary to set the optimum reference copy number a ₀ according to the developing unit 23 used in the copying machine. For example, as the value of the reference copy number a ₀ in this embodiment, a value between 5 and 10 is optimal.

If the variable a of the number of copies is smaller than the reference number of copies a ₀ in the above step 3, the number of times of toner replenishment is not set based on the detected value of the density of the reference toner image by the P sensor 1, and the step is performed. Control of the toner replenishing operation of 10 is started.

FIG. 5 is a sub-flowchart showing an example of the toner replenishment count setting in step 9 of FIG.
In this example, the toner supply level (0 to k) is set according to the P sensor level (0 to k) obtained in step 8 (steps 9-1 to 9-8). Next, based on the toner replenishment level (0 to k), the number of times of toner replenishment during copying of the number of copies a ₀ until the next P sensor detection is set (step 9-9). For example, when the toner replenishment level is 0, the number of times of toner replenishment at each copy is set to 0. Also, for example, when the reference copy number a ₀ is 5 and the toner replenishment level 3 occurs continuously, as shown in Table 1, the copy numbers 1, 3 and 5 are set.
The toner supply is set once for the first sheet. The number of sheets to be replenished with toner can be freely set. Further, for example, when the reference copy number a ₀ is 5 and the toner replenishment level is 10, the toner replenishment is set to be performed twice at each copy.

[Table 1]

Symbols ◯ and × in Table 1 respectively indicate the number of copies to which toner is replenished and the number of copies to which toner is not replenished, and an arrow P indicates the setting of the number of times of toner replenishment based on the value detected by the P sensor 1. The timing is shown. When the P sensor level is not within the range of the predetermined level, the toner end level,
The P sensor abnormal level is set (step 9-1).
0).

FIG. 6 is a sub-flowchart showing an example of the toner replenishing operation in step 10 of FIG. First, it is determined whether the number of copies a at that time is the number of copies for which toner is replenished (step 10-1).
When the number of copies is such that the toner is replenished, the replenishment clutch is turned on for a predetermined time and the agitator 43 is rotated to replenish toner from the hopper section 40 to the developing section 42 for the set number of times (step 10-2). ).

As described above, according to the present embodiment, the toner replenishment frequency is set and the toner replenishment operation is controlled with the reference copy number a ₀ as one unit, so that the toner is intermittently replenished by the rotation of the agitator 43. Even in a copying machine having the developing unit 23 in which the minimum replenishment amount is set higher than in the past, the toner concentration in the developing unit 42 may excessively rise when the minimum replenishment amount of toner is replenished. Therefore, it is possible to prevent the background stain of the image.

In this embodiment, as shown in step 10-2 of FIG. 6, the number of toner replenishments for each subsequent copy is set based on only the P sensor level. The toner supply frequency may be corrected in consideration of the size and / or the image area ratio of the original. The size of the transfer sheet may be set by the user or may be read by the time it takes to pass the position of the registration sensor or the like. In the case of manual paper feeding, the manual transfer paper size sensor may be used for reading. Further, the image area ratio of the document may be automatically read by the copying machine side, or may be manually entered by the user upon judgment. In this way, by correcting the set value of the number of times of toner replenishment based on the size of the transfer paper and / or the image area ratio of the document, the toner density of the toner density caused by the difference in the size of the transfer paper and / or the image area ratio of the document is corrected. Further appropriate toner replenishment can be performed according to the fluctuation.

Further, after setting the toner supplying times of the reference number of copies a _0, the size of the transfer sheet to be used for each copy in the reference number of copies a _0, and or on the basis of the image area ratio of the original, previously The toner supply may be performed by correcting the set toner supply number each time.

An example of controlling the toner replenishing operation will be described below in the case where one sheet is manually fed continuously. Figure 7
6 is a sub-flowchart showing an example of a toner replenishing operation in this example. First, it is judged whether or not one sheet is manually fed (step 10-1).
Corrects the preset toner replenishment count (whether or not to replenish toner, that is, 0 replenishment) based on the size of the transfer paper at the time of the previous manual paper feed copy (Step 10-2).
Next, it is determined whether or not the number of copies a this time is the number of copies for which toner is replenished (step 10-3). When the number of copies is to be replenished with toner, the replenishment clutch is turned on for a predetermined time and the agitator 43 is rotated, so that the hopper unit 40 is rotated by the corrected set number of times.
To replenish toner to the developing unit 42 (step 10-
4).

According to the present example, in a copying machine in which the size of transfer paper and / or the image area ratio often differs from copy to copy, such as one-sheet manual feeding, the size of transfer paper and / or the image of the original document. If the area ratio changes on the way, for example,
It is possible to quickly cope with a sudden phenomenon such as a rapid change in the toner density of the developing unit 42 when an almost black original is copied onto a transfer paper having a size larger than usual.

In this embodiment, the P sensor 1 detects the image density of the reference toner image, and based on the detected value, the subsequent predetermined reference copy number a ₀ is set as one unit during each copy. Set the number of toner replenishments,
Although the toner replenishment control is performed so that the toner density of the developing unit 42 of the developing unit 23 is constant, the number of toner replenishment may be set based on other detection values. For example,
The toner density in the developing unit 42 of the developing unit 23 may be detected by a toner density sensor such as a magnetic permeability sensor, and the toner replenishment count for each copy within the predetermined copy count a ₀ may be set based on the detected value. . Further, for example, regardless of the detection value of the P sensor 1, the predetermined number of copies a based on only the size of the transfer paper and / or the image area ratio of the document.
_The number of toner replenishment for each copy within ₀ may be set.

[0032]

According to the image forming apparatus of the present invention, the toner replenishment amount per image forming operation is limited, and accordingly, the toner replenishing amount per image forming operation is increased in order to achieve a predetermined maximum replenishment amount. Even in an image forming apparatus having a developing device in which the minimum replenishment amount of the toner is set to be high, the toner replenishment amount in the developing unit is increased because the higher replenishment amount is replenished for the predetermined plurality of image forming operations. There is an effect that it does not rise excessively and the background stain of the image can be prevented.

According to the image forming apparatus of the third aspect, by correcting the toner replenishment amount based on the size of the transfer material and / or the image area ratio of the document, the size of the transfer material and / or the image area of the document are corrected. The toner is appropriately replenished in accordance with the fluctuation of the toner density of the developing portion caused by the difference in the rate, so that the fluctuation of the image density is further reduced. Further, the toner replenishment amount in each image forming operation in a predetermined plurality of image forming operations, which is one unit, is defined as the transfer material size in each image forming operation or in the image forming operation immediately before the image forming operation, and / or the image. It is also possible to correct the toner based on the area ratio and replenish the toner. As a result, in an image forming apparatus in which the size and / or the image area ratio of the transfer material often differs for each image forming operation, such as when the transfer material is supplied by hand, the size of the transfer material and / or the image area ratio of the original document. In addition, since more appropriate toner replenishment is performed according to the change in the toner density of the developing unit due to the change of the toner density, the toner density suddenly changes due to the change of the transfer material size and / or the image area ratio of the document. There is an effect that it is possible to quickly respond to various phenomena.

[Brief description of drawings]

FIG. 1 is a flowchart of toner replenishment control according to an embodiment.

FIG. 2 is a front view showing a schematic configuration of a copying machine according to an embodiment.

FIG. 3A is a front view showing a schematic configuration of a developing unit of the copying machine. FIG. 3B is a perspective view of a drive unit of the developing unit.

FIG. 4 is a block diagram of a control system for toner supply control of the developing unit.

FIG. 5 is a sub-flowchart showing an example of setting the number of times of toner supply.

FIG. 6 is a sub-flowchart showing an example of a toner supply operation.

FIG. 7 is a sub-flowchart showing another example of the toner supply operation.

[Explanation of symbols]

 1 P Sensor 2 Main Control Section 20 Photosensitive Drum 21 Charging Charger 22 Eraser 23 Developing Unit 40 Hopper Section 41 Developing Sleeve 42 Developing Section 43 Agitator 48 Supply Clutch

Claims (3)

[Claims] 1. A developing section in which a developer carrying member is arranged, a toner containing section for containing toner to be supplied to the developing section, and a toner replenishing means for replenishing toner from the toner containing section to the developing section. An image forming apparatus including a developing device having the above-mentioned, wherein a control means for controlling an amount of toner replenishment by the toner replenishing means is provided with an image forming operation of a predetermined number of times as one unit. 2. A developing section in which a developer carrier is disposed, a toner containing section for containing toner to be supplied to the developing section, and a toner replenishing means for replenishing toner from the toner containing section to the developing section. In an image forming apparatus provided with a developing device having a sheet and a manual transfer material supplying means for manually supplying a transfer material, the toner replenishing means controls the toner replenishing amount by using a predetermined number of image forming operations as one unit. An image forming apparatus comprising a control means. 3. The control means is configured to control the toner replenishment amount based on the size of the transfer material and / or the image area ratio of the document.
Image forming device.