JP2001075438A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the degradation of image quality even in the case of printing many images of a low printing ratio by obtaining printing sheet number average developer consumption by developer consumption and a printing sheet number and developing a developer on the outside of a printing area on an image carrier in the case that the value is equal to or less than a prescribed value. SOLUTION: The printing sheet number average developer consumption is obtained by the developer consumption detected from a developer consumption detection means and the printing sheet number, and the developer is developed on the outside of the printing area on the image carrier in the case that the value is equal to or less than the prescribed value. In this image formation device, a pixel counter 9 which is the developer consumption detection means provided in a main body controller is connected to an exposure device 3 and the pixels of image data inputted to the exposure device 3 are counted. In this case, since the consumption of the developer is proportional to the number of the pixels, the consumption of the developer is detected by counting the number of the pixels. Also, in the main body controller, an electric/magnetic storage means 10 for integrating the number of the pixels of respective colors or the like is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus suitable for forming a color image.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a conventional full-color image forming apparatus. Hereinafter, description will be given with reference to the drawings. Organic photoreceptor (OPC) or A-
A photosensitive drum 1 as an image carrier (electrophotographic photosensitive member) formed by applying a photoconductor made of Si, CdS, Se, or the like is driven in a direction indicated by an arrow in FIG. 2 uniformly charges to a predetermined potential. Next, the exposure device 3 scans the photosensitive drum 1 with light based on a signal according to the image pattern of yellow Y, and forms an electrostatic latent image on the photosensitive drum 1. Further, when the photosensitive drum 1 advances in the direction of the arrow, the developing device 4a containing the yellow developer among the developing devices 4a, 4b, 4c, and 4d supported by the support 5 faces the photosensitive drum 1 so as to face the photosensitive drum 1. 5, the electrostatic latent image on the photosensitive drum 1 is developed as a developer visible image by the selected developing device 4a. Next, the developer visible image is transferred to the transfer belt 6 of the intermediate transfer body 6.
1 is transferred.

[0003] The intermediate transfer member 6 is a transfer belt 61 made of rubber such as EPDM, NBR, urethane, and silicone rubber.
Are stretched over three rollers of a driving roller 62, a driven roller 63, and a tension roller 64. The transfer belt 61 is driven in the direction of the arrow in the figure by rotating the drive roller 62 in the direction of the arrow in the figure by a motor (not shown).

A primary transfer roller 65 having a conductive sponge layer provided on a shaft is in contact with the photosensitive drum 1 via a transfer belt 61. A bias is applied to the primary transfer roller 65 from a high voltage power supply (not shown), and the developer visible image on the photosensitive drum 1 is transferred onto the transfer belt 61. Thereafter, the transfer residual developer on the photosensitive drum 1 is cleaned by a cleaning device 7 having a known blade means.

[0005] The above steps are further performed for magenta M, cyan C, and black Bk to form a plurality of developer visible images on the transfer belt 61. When the four color developer visible images are transferred onto the transfer belt 61, the recording paper P synchronized with the movement of the transfer belt 61 is conveyed, and
A secondary transfer roller 66 having the same configuration as the primary transfer roller 65 abuts on the transfer belt 61 via the recording paper P, and a bias is applied from a high-voltage power supply (not shown).
The four-color developer visible image on 1 is collectively transferred onto the recording paper P. The recording paper P to which the four-color developer visible image has been transferred is melted and fixed by a conventionally known heating and pressure fixing device 8 to obtain a color image.

The untransferred developer on the transfer belt 61 is a cleaning device 67 such as a fur brush and a web which can be separated from and separated from each other.
Will be cleaned by

FIG. 10 shows a conventional developing device 4 (4a to 4a).
An example of d) is shown. The developing device 4 of this embodiment is of a one-component developing type. The one-component developing system is superior to the two-component developing system in the following points, and is particularly suitable for a cartridge system which can be replaced by a user. That is, 1. Since only the non-magnetic particles are used as the developer, a means for stirring the magnetic particles and the non-magnetic particles is unnecessary.

[0008] 2. A mechanism for keeping the mixing ratio of the magnetic particles and the non-magnetic particles constant is unnecessary.

3. No magnet is required in the developing sleeve.

As described above, it is possible to provide a simple, compact, and low-cost device.

Hereinafter, the developing device 4 will be described with reference to the drawings.

The developing device 4 shown in FIG. 10 is suitable for a developing system in which the sleeve 41 as a developer carrier and the photosensitive drum 1 are not in contact with each other. The developer in the developer hopper 44 is
The developer is sent from the developer hopper 44 to the adjacent developing chamber 45 by the stirring member 46 rotating in the direction of the arrow in the drawing. The developer sent to the developing chamber 45 is applied by a coating roller 42 provided with a sponge layer such as a urethane sponge on a metal core and rotating in the direction of the arrow in the figure in the direction of the arrow consisting of a rigid body such as aluminum, SUS, and resin. It is supplied on a rotating sleeve 41. The developer supplied on the sleeve 41 is applied in a thin layer by a blade 43 provided with a rubber or elastomer such as urethane rubber or silicon rubber on a support plate as an elasticity providing member made of phosphor bronze, SUS, or the like. Sleeve 41 to which bias is applied from a bias power supply (not shown)
And the photosensitive drum 1 are 50 to 5 by a space member (not shown).
The electrostatic latent image held on the photosensitive drum 1 is maintained at a gap of 00 μm, and is developed into a visible image.

FIG. 11 shows the sleeve 41 and the photosensitive drum 1.
A developing device suitable for a developing system in which the contact is made is shown. The difference from the non-contact developing device is that the sleeve 41 is an elastic sleeve made of rubber such as urethane rubber, silicon rubber, or NBR, and is in contact with the photosensitive drum 1.
Further, the blade 43 may be a blade in which rubber or an elastomer is provided on the above-mentioned elastic support plate, but as shown in this figure, an elastic metal plate such as phosphor bronze or SUS is bent into an L-shape, and a bent portion is formed. Is preferably in contact with the sleeve 41.

[0014]

However, the conventional image forming apparatus has the following problems. That is,
If a document having a low printing ratio is continuously printed, the reproducibility of a highlight portion is reduced, and the granularity of the entire image is increased, resulting in a reduction in image quality. The reason for this is that, although the one-component developing device has the above-mentioned advantages, when the developer is not consumed in a low print image, the unused developer is repeatedly rubbed with the application roller or the blade, and the developer is not consumed. This may cause deterioration of charging characteristics.

Particularly, in a color image forming apparatus, an original having a very low printing rate, such as only a company name logo, a part of a ruled line, and only characters to be emphasized, is printed. Normal,
As a standard developer use state, A4 or letter size recording paper is used, and an image printing rate of 4% to 5% is assumed. On the other hand, a color image forming apparatus is used as a document of image data such as a photograph having a high image printing rate. In this case, the required image quality is higher than that of a normal character document, and the image quality is more seriously degraded. Met. In this case, the user has to replace the developing device with a new one and print again.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing deterioration of image quality even when many images having a low printing ratio are printed.

[0017]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
In an image forming apparatus that visualizes a latent image on an image carrier with a developing device, the image forming apparatus has a developer consumption detecting unit, and the developer consumption detecting unit detects the developer consumption and the number of printed sheets. The image forming apparatus is characterized in that an average developer consumption of the number of printed sheets is obtained, and when this value is equal to or less than a predetermined value, the developer is developed outside a printing area on the image carrier.

It is preferable that an electric or magnetic storage unit is provided, and the storage unit stores the developer consumption and the number of printed sheets. According to another aspect, there is provided a process cartridge including at least the developing device, which is detachable from an image forming apparatus main body, wherein the process cartridge has an electric or magnetic storage unit, and the developer is stored in the storage unit. It is preferable to store the consumption amount and the number of printed sheets. It is preferable that the developer consumption detecting means is means for counting pixels of an image to be printed. According to another aspect, it is preferable that the developer consumption detecting means is a means for detecting a developer amount in the developing device.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows an image forming apparatus according to the present embodiment. The image forming apparatus according to the present embodiment has a configuration substantially similar to that of the conventional example. Therefore, the description of the overall configuration and functions will be omitted, and mainly the features of the present invention will be described. The same members as those described above are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, the exposure device 3 is connected to a pixel counter 9 serving as a developer consumption detecting means provided in a controller (not shown) of the image forming apparatus main body. The pixels of the image data are counted. Of course, the pixel counter 9 may be provided in an image forming controller (not shown).

Further, the controller for controlling the main body of the image forming apparatus is provided with an electric or magnetic storage means 10 for accumulating the number of pixels of each color and the number of images. Specifically, for example, a RAM, a rewritable ROM, or the like is used as the electrical storage unit. In addition, as the magnetic storage means, a magnetic recording medium, a magnetic bubble memory, a magneto-optical memory, or the like is used. In the present embodiment, NV (Non Volati) is used in terms of ease of handling and cost.
le) Use RAM.

By the way, the number of images is the number of prints when viewed for each color. When a full-color image using four colors is printed, yellow Y, magenta M,
It is assumed that one image is printed for each color of cyan C and black Bk. When a monocolor image using only Bk is printed, one image is printed for only Bk.

The number of pixels is the number of pixels of an image to be actually printed in the unit of the basic resolution of the image forming apparatus. In the image forming apparatus main controller, the image is usually converted into a scanned image only. Because you can understand
Pixels may be counted for each scan. When the pixels are counted by the image forming controller, the pixels may be counted when converted into the scan image as described above, or may be calculated from the image shape before the conversion into the scan image. For example, when printing a 2 inch x 3 inch solid image at a basic resolution of 600 dpi, 2 x 600 x
3 × 600 = 216,000 pixels.

Generally, a pixel has such a large number. If the pixel is stored in the NVRAM as it is, an NVRAM having a large storage capacity is required, which increases the cost. Therefore, the counted pixels are preferably compressed to about 1/1000 to 1 / 10,000.

When a multi-valued pixel is used, the pixel may be counted at a ratio to the maximum value of the pixel. For example, 1
When using 8 bits (0 to 255) of multi-value information per pixel, a value obtained by dividing the multi-value information of an actual pixel by 255 which is the maximum value may be used. For example, if the multi-value information of a certain pixel is 6
In the case of 4, the number of pixels may be 64/255 = 0.25.

Here, since the consumption of the developer is proportional to the number of pixels, the consumption of the developer can be detected by counting the number of pixels.

Next, a recovery operation (refresh operation) when the image quality is deteriorated will be described. FIG. 2 is an expanded view of the print image, and the arrow direction in the figure is the transport direction of the recording paper P. A is an image area recorded on recording paper, and B shown by hatching in the figure is a developer refresh image in a non-image area, which is not recorded on recording paper.

In the developing device 4 shown in FIG. 10 described above, the developer having deteriorated charging characteristics near the sleeve 41 is
The developer is consumed by the developer refreshing image B, and a new developer whose charging characteristics are not deteriorated is supplied to the vicinity of the sleeve 41. When the image B for developer refresh formed on the photosensitive drum 1 contacts the transfer belt 61, a bias having a polarity opposite to a normal transfer bias is applied to the primary transfer bias roller 65 when the image B comes into contact with the transfer belt 61. Cleaning is performed by the cleaning device 7 without transferring onto the surface 61.
Alternatively, the image may be transferred onto the transfer belt 61 and cleaned by the transfer belt cleaner 67.

The width L of the developer refreshing image B is preferably the same as that of the developer application area on the sleeve 41, and the length D is preferably equal to or more than one rotation of the sleeve 41 on the photosensitive drum 1. For example, the diameter of the sleeve 41 is 16 mm,
When the sleeve 41 is rotating at a moving speed of 150% of the moving speed of the photosensitive drum 1, 16 × π {1.5}
Since the length is 33 mm, the length D of the developer refreshing image B is preferably about 33 mm. However, if the developer refreshing image length D is too long, cleaning failure occurs in the cleaning device 7 or the transfer belt cleaner 67. Therefore, the length D is made shorter than the above-described length, and a plurality of printing sequences are used. The developer may be divided and consumed. In this case, the sequence may be created so that the developer is consumed over the entire periphery of the sleeve 41.

In the above description, the developer refresh image is created during a normal printing sequence. However, during continuous printing, a non-image area or a non-image area between recording sheets may be used for each color. Before image exposure is performed,
It may be performed at the time of pre-rotation or at the time of post-rotation during discharge. Further, a sequence for creating a developer refreshing image may be provided separately. In this case, since there is no image to be recorded on the recording paper, the developer refreshing image may be created at an arbitrary location.

Next, the flow of the developer refresh will be described with reference to FIG.

In step 0, the number of print images nk, ny, nm, nk of each color and the total number of pixels Pk, Py, Pm, Pc stored in the NVRAM 10 are loaded.

In step 1, the print mode is determined,
In the case of a mode for printing a full-color image using four colors of Y, M, C, and Bk, the flow proceeds to Step 2, and in the case of a mode for printing a mono-color image using only Bk, the flow proceeds to Step 3.

In step 2, the number n of print images of four colors n
One is added to each of k, ny, nm, and nc, and the process proceeds to step 4.

In step 3, the number of Bk print images n
Add 1 to k only and go to step 5.

In step 4, four color pixels pk, py,
pm and pc are counted, and the process proceeds to step 6.

In step 5, only the pixel pk of Bk is counted, and the process proceeds to step 6.

In step 6, the four-color pixels pk, py, pm, and pc counted in step 4 are added to the accumulated pixel numbers Pk, Py, Pm, and Pc of each of the four colors.
Go to 9, 10, 11.

In step 7, the Bk pixel pk counted in step 5 is added to the accumulated pixel number Pk of Bk, and the process proceeds to steps 8, 9, 10, and 11.

In steps 8, 9, 10, and 11, the number of images nk, ny, nm, and nc and the predetermined number of images n
Compare 0k, n0y, n0m, and n0c. n
k <n0k, ny <n0y, nm <n0m, nc <n0
In the case of c, steps 12, 14, 16, 18 respectively
And in steps 12, 14, 16, and 18, N
Nk, ny, nm, nc and Pk, P
The flow of writing y, Pm, and Pc ends.

Here, a predetermined number of images n0k, n
0y, n0m and n0c can be printed at a low printing rate,
The number of sheets may be set so that the developer does not deteriorate, and specifically, about 100 to 1000 sheets is preferable.

On the other hand, in steps 8, 9, 10, and 11, n
k ≧ n0k, ny ≧ n0y, nm ≧ n0m, nc ≧ n0
In the case of c, steps 13, 15, 17, 19 respectively
Proceed to.

In steps 13, 15, 17, and 19, the magnitude of the image printing rate (average amount of developer consumed in the number of printed sheets) is determined. Specifically, the cumulative pixel numbers Pk, P
y, Pm, Pc and a predetermined cumulative number of pixels P0k, P0
y, P0m, and P0c, and Pk ≧ P0k, Py ≧
When P0y, Pm ≧ P0m, and Pc ≧ P0c, the process proceeds to steps 20, 22, 24, and 26, respectively.

Pk <P0k, Py <P0y, Pm <P0
If m, Pc <P0c, it is determined that the printing rate is low,
Proceeding to steps 21, 23, 25 and 27, respectively, the above-described developer refresh is performed. Here, the predetermined cumulative pixel numbers P0k, P0y, P0m, and P0c are expressed by the following equations when the A4 size 4% printing rate is set. The print area of A4 was 20 cm × 28 cm.

P0k = (20 ÷ 2.54 × 600) ×
(28 ÷ 2.54 × 600) × 0.04 × n0k P0y = (20 ÷ 2.54 × 600) × (28 ÷ 2.5
4 × 600) × 0.04 × n0y P0m = (20 ÷ 2.54 × 600) × (28 ÷ 2.5
4 × 600) × 0.04 × n0m P0c = (20 ÷ 2.54 × 600) × (28 ÷ 2.5
4 × 600) × 0.04 × n0c Predetermined number of images n0k, n0y, n0m, n0c
Is set to 100, a predetermined cumulative pixel P0k,
P0y, P0m, and P0c ≒ 12,500 × 10 ⁴ .

In steps 20, 22, 24 and 26, n
k, ny, nm, nc and Pk, Py, Pm, Pc are reset to 0, and these values are written in the NVRAM 10 in steps 28, 29, 30, 31 and the flow ends.

Table 1 below shows the results of studies on the number of prints and the state of image deterioration at the time of printing images having different print ratios. Further, the present embodiment in which the developer refresh operation was performed in the above flow and the case where the developer refresh operation was not performed as a comparative example were studied. Note that the developing device has a 6% 4% ratio image.
It was set to print 000 sheets.

[0050]

[Table 1] As can be seen from the above results, when the image ratio is 8%,
Normal images could be printed up to 3000 sheets in both the comparative example and the example (shown by ○ in the table). At the time of 3000 sheets, all the developer in the developing device was consumed (indicated by-in the table).

When the image ratio was 4%, normal images could be printed up to 6000 sheets in both the comparative example and the embodiment.

In the case of the image ratio of 2%, in the embodiment, 500
Although a normal image could be printed up to 0 sheets, in the comparative example, the image was reduced in density and increased in granularity at 4000 sheets (indicated by △ in the table). Further, after 5,000 sheets, in addition to the decrease in density and the increase in graininess, density unevenness occurred in a streak-like manner, resulting in a remarkable decrease in image quality (indicated by x in the table).

When the image ratio is 1%, in the embodiment, 600
Although a normal image could be printed up to 0 sheets, in the comparative example, 30 images were printed.
At the time of 00 sheets, an image having a reduced density and increased granularity is obtained. After 4000 sheets, in addition to the decreased density and increased granularity, density unevenness occurs in the form of stripes, and the image quality is significantly reduced. invited.

When the image ratio of the comparative example was 1% or 2%, the developer remained in the developing device.

As described above, in this embodiment, the developer consumption is detected based on the pixel count, and the average amount of the developer consumed is determined. If the developer consumption is equal to or less than the predetermined value, the developer is developed in the non-printing area. Refreshing the developer can prevent image quality deterioration.

In this embodiment, the nonvolatile storage means is provided in the apparatus main body, but may be provided in the developing device. In this case, even when the developing device in use is replaced, the number of prints so far is stored in the storage means provided in the developing device, so that appropriate control can be performed, which is more preferable.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. The configuration of the image forming apparatus according to the present embodiment is substantially the same as that described above. Therefore, the description of the overall configuration and functions will be omitted, and the features will be described. Also, the same members are given the same reference numerals,
The description is omitted.

As shown in FIG. 4, the image forming apparatus according to the present embodiment has an antenna electrode 48 (48a, 48b, 48b) for detecting the amount of developer in each developing device 4 (4a, 4b, 4c, 4d).
48c, 48d) and a detection circuit 49.

More specifically, referring to FIG. 5, the capacitance between the developing sleeve 41 and the antenna electrode 48 of the developing device 4 changes according to the amount of the developer in the developing device 4.
Although an alternating electric field is applied to the developing sleeve 41 as a developing bias by a developing bias power supply 47, a voltage level induced in the antenna electrode 48 changes according to the difference in the capacitance. The voltage induced in the antenna electrode 48 is integrated and amplified by the detection circuit 49, and the amount of the developer in the developing device 4 is detected.

FIG. 6 is a graph showing the relationship between the voltage level from the antenna electrode 48 and the amount of developer in the developing device 4.
Here, the detection circuit 49 was adjusted so that the change was 1 to 5 V when the developing device contained 0 g to 200 g of the developer.

As can be seen from the figure, when the developer in the developing device 4 is full (200 g), the output is 5 V, and as the developer decreases, the capacitance between the developing sleeve 41 and the antenna electrode 48 becomes smaller. And the output of the detection circuit 49 also decreases. When the developer in the developing device 4 runs out, the output is 1V.

The relationship between the output voltage of the detection circuit 49 and the amount of developer in the developing device 4 is stored in a main body in advance as a reference table, so that the image forming apparatus can
The amount of the developer inside can be detected. Here, the consumed amount of the developer between the predetermined number of sheets is detected, and many images with a low printing rate are printed.
By performing the developer refresh described in the embodiment, it is possible to prevent image quality deterioration.

FIG. 7 shows a control flow of this embodiment. Here, the consumption of the developer is detected every 100 sheets of printing,
The case where the developer refresh operation is performed will be described.
The processing for each color may be performed in the same manner as in the first embodiment, and a description thereof will not be repeated.

In step 0, first, the number of prints is initialized to zero. This is performed when the power is turned on, when the developing device is replaced, and at step 8 described later.
Next, in step 1, the actual number n of printed sheets is counted. In step 2, the value of the number n of printed sheets is compared. If 0, the process proceeds to step 3. If 0 <n <100, the process proceeds to step 5.
If n = 100, the process proceeds to step 4.

In step 3, the developer amount q0 in the developing device at the time of the 0th sheet is measured. In step 5, since the number of prints is less than 100, the process returns to step 1 and the number of prints is counted. The number of prints is added and 1
When the number of sheets reaches 00, in step 4, the developer amount q100 in the developing device at the time of the 100th sheet is measured.

Subsequently, in step 6, the amount of developer Δq consumed between printing 100 sheets is obtained as a difference value between q0 and q100. At step 7, the developer consumption amount Δq is compared with a predetermined consumption amount Q. Δq ≧
In the case of Q, since the developer more than the set amount has been consumed, the developer refresh is not executed, and the process proceeds to step 8. On the other hand, if Δq <Q, only the developer less than the set amount is consumed, so that the developer is refreshed in step 9 and the process proceeds to step 8.

In step 8, the process returns to step 0, and the number n of printed sheets is initialized to 0. Then, the processing for printing the next 100 sheets is performed again.

Here, regarding the predetermined consumption amount Q, the developer consumption amount per sheet when an image having a 4% image ratio is printed depends on the developer used.
g to 0.05 g. Here, assuming that 0.03 g of the developer is used, 3 g of the developer is consumed for 100 sheets. Therefore, by setting Q to 3 g, the developer refresh is executed when the average image printing rate of 100 sheets is 4% or less.

In the present embodiment in which the developer refresh operation is performed in the above-described flow, and in the case where the developer refresh operation is not performed as a comparative example, the number of printed sheets and the number When the state of image deterioration was examined, the same results as in Table 1 above were obtained.

In this embodiment, the case where the non-volatile storage means is not provided has been described. However, as in the first embodiment, the storage means may be provided in the apparatus main body or the developing device. In this case, the number n of printed sheets and the amount q of developer can be stored, and even if printing is performed on less than 100 sheets and the power supply of the apparatus main body is turned off, the average number of printed sheets of the developer is accurately detected. be able to.

In this embodiment, the case where the antenna system for detecting a change in capacitance is used as the system for detecting the developer in the developing device is described. Also, a method using a piezo element can be used.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIG. Components having the same configuration and operation as those of the above-mentioned members are denoted by the same reference numerals.

As shown in FIG. 8, the image forming apparatus of this embodiment has four process cartridges 11a, 11b, 1
1c and 11d are juxtaposed along the horizontal portion of the transfer belt 61, and image formation of four colors is performed in parallel to increase the speed.

Each of the process cartridges 11a to 11d
Are photosensitive drums 1a, 1b, 1c, 1d, charging rollers 2a, 2b, 2c, 2d, developing devices 4a, 4d, respectively.
b, 4c, 4d, cleaners 7a, 7b, 7c, 7d, and storage means 10a, 10b, 10c, 10d are integrated with each other and are detachable from the image forming apparatus main body.

Each of the process cartridges 11a to 11a
Exposure devices 3a, 3b, 3c provided corresponding to 1d
A pixel counter 9 provided in the image forming apparatus main body controller is connected to 3d, and counts the pixels of the image data input to the exposure devices 3a to 3d. The counted pixels and the number of printed sheets are stored in the respective storage units 10a to 10d.

Then, by the same method as in the first embodiment,
The average developer consumption of the number of printed sheets is obtained from the pixels of the image to be printed and the number of printed sheets. When the consumption amount is equal to or less than a predetermined value, the developer is refreshed.

In this way, the present embodiment can provide the same effects as the above embodiment.

In the above embodiment, the case where the present invention is applied to a color image forming apparatus has been described.
It goes without saying that the present invention can be applied to a monochrome image forming apparatus.

[0079]

As is apparent from the above description, according to the image forming apparatus of the present invention, the image forming apparatus has the developer consumption detecting means. The average number of printed pages is used to determine the average consumption of the developer, and if this value is equal to or less than a predetermined value, the developer is developed outside the printing area on the image carrier to print many images with a low printing ratio. In this case, deterioration of image quality can be prevented, and a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a developed view showing a printed image including a developer refreshing image according to the first to third embodiments.

FIG. 3 is a flowchart illustrating a control flow according to the first embodiment.

FIG. 4 is a schematic configuration diagram illustrating an image forming apparatus according to a second embodiment.

FIG. 5 is an enlarged explanatory view showing the developing device of FIG. 4;

FIG. 6 is a graph showing characteristics of a developer remaining amount detecting unit in the second embodiment.

FIG. 7 is a flowchart illustrating a control flow according to the second embodiment.

FIG. 8 is a schematic configuration diagram illustrating an image forming apparatus according to a third embodiment.

FIG. 9 is a schematic configuration diagram illustrating an example of a conventional image forming apparatus.

FIG. 10 is an enlarged explanatory view showing the developing device of FIG. 9;

FIG. 11 is a configuration diagram illustrating another example of the developing device.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum (image carrier / electrophotographic photosensitive member) 4 developing device 9 pixel counter (developer consumption detecting means) 10 NVRAM (storage means) 11 process cartridge 48 antenna electrode (developer consumption detecting means) 49 detection circuit (Developer consumption detection means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuhiko Nishimura 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H027 DA32 DA45 DD01 DD02 DE07 EC10 ED06 ED08 EF09 HB05 HB15 ZA07 2H077 DA15 DA22 DA24 DA42 DA78 DB13 DB14 DB25 GA03 GA12

Claims (5)

[Claims] 1. An image forming apparatus for visualizing a latent image on an image carrier with a developing device, comprising a developer consumption detecting unit, wherein the developer consumption detected by the developer consumption detecting unit is detected. An average amount of developer consumed by the number of printed sheets based on the number of printed sheets and the number of printed sheets, and when the value is equal to or less than a predetermined value, the developer is developed outside the printing area on the image carrier. 2. It has electric or magnetic storage means,
2. The image forming apparatus according to claim 1, wherein the storage unit stores the developer consumption amount and the number of printed sheets. 3. A process cartridge including at least the developing device, the process cartridge being detachably attachable to an image forming apparatus main body.
2. The image forming apparatus according to claim 1, wherein the process cartridge has an electrical or magnetic storage unit, and stores the developer consumption and the number of printed sheets in the storage unit. 4. An image forming apparatus according to claim 1, wherein said developer consumption detecting means is means for counting pixels of an image to be printed. 5. The image forming apparatus according to claim 1, wherein said developer consumption detecting means is means for detecting a developer amount in said developing device.