JPH07287495A - Image forming device - Google Patents

Abstract

PURPOSE:To control the supply of toner in accordance with environment, to surely prevent the blade of a cleaning device from turning up and to make delay in starting image forming as little as possible by forming a toner belt by developing bias potential when a power source is turned on or when image forming operation is not performed for a long time. CONSTITUTION:A toner image forming signal output means 19 outputs a toner image forming signal at a specified time such as the power source of the device is turned on. A control means 20 controlling development with toner on a photoreceptor 7 outputs a toner development signal for performing toner development on the photoreceptor 7 according to the toner image forming signal in timing when the image is not transferred to transfer paper. An environment detection means 21 detects the environment such as temperature and humidity surrounding a color image forming device and a toner image width control means 22 controls the bias potential for a developing device 9 to obtain the width o the toner image decided based on the environment detection signal.

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 or a printer, and more particularly to an image forming apparatus in which toner can be developed on a photosensitive member at a timing at which it is not transferred onto a transfer sheet at a predetermined time such as when power is turned on. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, in a color image forming apparatus such as a color copying machine or a color printer, a color image forming unit including a photoconductor, a charging device, a developing device, a static eliminator and a cleaning device has a number of colors, for example, Arranged in tandem for each of the four colors of black, yellow, magenta and cyan,
A method is known in which a color image is sequentially formed for each color by these color image forming units. This method will be specifically described with reference to FIG.
The image forming units 5a, 5b, 5c, 5d for each of the four colors are arranged in tandem along the transfer belt 3 in the vicinity of the endless transfer sheet conveying transfer belt 3 driven by the driven roller 2 and the driven roll 2. ing.

Image forming units 5a, 5b, 5c, 5d
Is an exposure device 6a, 6b, 6 that exposes each of four colors.
c, 6d, photoreceptors 7a, 7b, 7c, 7d on which images are formed on the surface for each of the four colors, and chargers 8a, 8b, 8c, 8d, four colors for charging the corresponding photoreceptors for each of the four colors The surface of each of the developing devices 9a, 9b, 9c, 9d for developing the latent image on the corresponding photoconductor and the corresponding photoconductor 7a, 7b, 7c, 7d for each of the four colors is cleaned. Cleaning brushes 11a, 11b, 11c, 1 for every four colors
1d and cleaning blades 12a, 12b, 12c12
It is composed of d. These image forming units 5
In addition to a, 5b, 5c, 5d, photoconductors 7a, 7b for each four colors,
The transfer devices 10a, 10b, 10c, 10d for each four colors for transferring the developed images 7c, 7d onto the transfer belt 3 for each four colors, and the cleaning brush 13 and the cleaning blade 14 for cleaning the surface of the transfer belt 3 are arranged. It is set up.

Then, each image forming apparatus unit 5a, 5
b, 5c, 5d, the photoconductors 7a, 7b, 7
c, 7d are uniformly charged by the chargers 8a, 8b, 8c, 8d, and then the image of the original is formed on the photoconductors 7a, 7b, 7c, 7d by the exposure devices 6a, 6b, 6c, 6d. Exposure is performed for each color, and an electrostatic latent image of each color is formed on each photoconductor 7a, 7b, 7c, 7d. Then, the photoconductors 7a, 7b,
The electrostatic latent images on 7c and 7d are developed by developing devices 9a, 9b, 9c and 9d for the respective colors, and the developed toner images of the respective colors are transferred to the transfer devices 10a, 10b, 10c and 10d.
Thus, each color is sequentially transferred onto the transfer paper on the transfer belt 3.

After the transfer is completed, the photoconductors 7a, 7b, 7c, 7
The toner of each color remaining on d is first scraped off by the cleaning brushes 11a, 11b, 11c, 11d, and the rest is disturbed. Further, the cleaning blades 12a, 12b, 1 arranged on the downstream side of the cleaning brushes 11a, 11b, 11c, 11d.
By 2c12d, each residual toner on each photoconductor 7a, 7b, 7c, 7d is completely scraped off. At this time, when the residual toners on the photoconductors 7a, 7b, 7c, 7d are sufficiently scraped off by the cleaning blades 12a, 12b, 12c12d, the cleaning brushes 11a, 11b,
11c and 11d are not always necessary and can be omitted.

On the other hand, the transfer sheet on which all the four color toner images have been transferred is peeled off from the transfer belt 3 and conveyed to a fixing device (not shown), and the toner image on the transfer sheet is fixed by the fixing device. After that, the residual toner on the transfer belt 3 is scraped off by the cleaning brush 13 and the cleaning blade 14.

In this way, a series of image forming cycles are sequentially performed for each color by the four sets of image forming units 5a, 5b, 5c and 5d, whereby a color image is formed on the transfer sheet.

In such a color image forming apparatus, the toner images formed on the respective photoconductors 7a, 7b, 7c and 7d are transferred in order to form the same image on the transfer paper in sequence for each different color. It is necessary to accurately transfer to a predetermined position on the paper, and it is also necessary to match the densities of the four colors of black, yellow, magenta, and cyan. For this reason, when the power is turned on or when the copying operation is not performed for a long time, it is necessary to perform the position alignment control and the density alignment control for controlling the surface potential of the photoconductors 7a, 7b, 7c, 7d, the toner concentration, and the like. There is. To perform such control, the image forming units 5a, 5
It is performed by driving b, 5c and 5d.

Further, in such a color image forming apparatus, in order to accurately transfer the toner image formed on each photoconductor 7a, 7b, 7c, 7d to the position of the transfer paper, each photoconductor 7a, 7b , 7c, 7d are configured to be always interlocked. For this reason, when this color image forming apparatus is used in a single color mode such as black, the image forming unit of the color corresponding to the single color mode is not only driven but also related to the color corresponding to the single color mode. Therefore, other image forming units that do not need to be driven are also driven.

By the way, in such a color image forming apparatus, an image forming unit that does not form a latent image may be driven when it is not necessary as described above. Even in such a case, the life of the developer is extended. Therefore, each developing device of the image forming unit that does not form a latent image is not driven. For this reason, no toner is supplied to the photoconductor of the image forming unit that does not form a latent image at the time of position control or density control as described above, or in the single color mode.
There is almost no toner on the surface of the photoreceptor on which no image is formed. Therefore, when the photoconductor is driven in such a state, the cleaning blade 1 of the image forming units 5a, 5b, 5c, 5d, as shown by the chain double-dashed line in FIG.
Edges of 2a, 12b, 12c, 12d and photoconductors 7a, 7
Toner as a lubricant is not supplied between the cleaning blades 12a, 12b and 12d.
There is a problem that the c and 12d are rolled up.

Therefore, by developing the toner on the photosensitive member at a timing when it is not transferred to the transfer paper,
An image forming apparatus is provided in which the toner on the photoconductor is supplied between the cleaning blade and the photoconductor without being transferred so that the toner functions as a lubricant between the cleaning blade and the photoconductor. , For example, JP-A-2-
It is proposed by Japanese Patent No. 148084. According to the image forming apparatus of this publication, the toner is reliably supplied between the cleaning blade and the photoconductor,
The above problems will be resolved.

[0012]

By the way, the above-mentioned curling of the cleaning blade is likely to occur at high temperature and high humidity, and is less likely to occur as the temperature shifts to low temperature and low humidity. However, in the image forming apparatus of the above-mentioned publication, the amount of toner supplied between the cleaning blade and the photoconductor is supplied regardless of the environment surrounding the image forming apparatus such as temperature and humidity. A certain amount of toner is not always supplied between the cleaning blade and the photoconductor. Therefore, in the image forming apparatus of the above-mentioned publication, a toner amount less than the required amount is supplied at high temperature and high humidity, or an excessive amount of toner is supplied at low temperature and low humidity, resulting in a large toner consumption amount. There is a risk of becoming.

Further, in the image forming apparatus of the above publication, the exposure devices 6a, 6b, 6c and 6d are provided with ROs for emitting image signals.
Since the S (Roster Output Scanner) is used, it takes a predetermined time (time until the rotation of the polygon mirror becomes constant) before the ROS becomes writable when the power is turned on. Therefore, if the toner image signal is sent after that, the transfer of the first transfer sheet is delayed, and as a result, the start of image formation is delayed.

The present invention has been made in view of the above problems, and an object thereof is to create a toner band when the power is turned on or when the image forming operation is not performed for a long time. (EN) An image forming apparatus capable of controlling toner supply in accordance with the environment surrounding the image forming apparatus to reliably prevent the blade of a cleaning device from curling, and minimizing a delay in image forming start. That is.

[0015]

In order to solve the above-mentioned problems, the invention of claim 1 provides a photoconductor on which an electrostatic latent image is formed, a charger for charging the photoconductor, and a photoconductor on the photoconductor. An image forming unit including a developing device for developing an electrostatic latent image with toner, a static eliminator for removing the charge on the photoconductor, and a cleaning device for removing foreign matter such as toner adhering to the photoconductor, and the photoconductor. An exposure device that exposes the photoconductor to form the electrostatic latent image, a transfer device that transfers the toner image developed on the photoconductor onto a transfer sheet, and a long time after the power is turned on or after the image formation is completed. An image forming apparatus comprising: a toner development control unit for developing a toner on the photoconductor at a timing at which the toner is not transferred to the transfer sheet at a predetermined time such as a start of a reimage forming operation after a lapse of time. , Further, the picture And environment detecting means for detecting an environment surrounding the forming apparatus, the width of the toner image at the time,
And a toner image width control means for controlling based on the environment of the image forming apparatus detected by the environment detection means.

The invention of claim 2 is characterized in that the environment is a temperature and / or humidity surrounding the image forming apparatus. According to a third aspect of the invention, in the image forming apparatus, the transfer device has an endless belt-shaped transfer belt, and four developing devices and four photoconductors are tandem along the transfer belt. It is a color copying machine disposed in the.

According to a fourth aspect of the invention, in the image forming apparatus, four developing devices arranged on a rotating body are sequentially opposed to one photosensitive member, and the transfer device has a transfer drum. The feature is that it is a color copier.

[0018]

In the image forming apparatus of the present invention configured as described above, the toner is developed on the photosensitive member at a predetermined time such as when the power is turned on or when the re-image forming operation is started after a long time has passed after the image formation is completed. A predetermined developing bias potential is applied to the developing device by the control means, and at the timing when the developing device does not transfer the toner to the transfer sheet, the toner is developed on the photoconductor to form a toner image. In this case, the environment detecting means detects the environment surrounding the image forming apparatus such as temperature and humidity, and the toner image width control means controls the width of the toner image based on the detected environment.

As described above, in the present invention, since the toner is developed on the photoconductor at the timing when it is not transferred to the transfer paper, the toner on the photoconductor is not transferred and the cleaning blade and the photoconductor are not transferred. Will be supplied during. Therefore, the toner comes to function as a lubricant between the cleaning blade and the photoconductor,
As a result, the cleaning blade can be prevented from turning up.

Further, since the width of the toner image formed on the photoconductor is controlled based on the environment surrounding the image forming apparatus, the toner supply amount can be properly controlled according to the environment, and the cleaning blade The curling is prevented more reliably, and the toner consumption amount for forming the toner image is suppressed to the minimum.

Further, since the toner image can be formed regardless of the rise of the ROS, the first transfer sheet can be conveyed faster than the method of forming the toner image by the ROS. Therefore, the start of image formation becomes faster.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. In describing this embodiment, this embodiment will be described using the color image forming apparatus shown in FIG.
FIG. 2 is an enlarged detailed view showing one of the image forming units shown in FIG. 1 on the most upstream side. The configuration of each of the other image forming units is the same as that of the image forming unit shown in FIG. Further, FIG. X is a diagram showing the basic configuration of an embodiment of the image forming apparatus of the present invention.

In FIG. 2, numeral 15a is an erase lamp, this erase lamp 15a is for erasing the charge remaining on the photosensitive member 7a, 16a is a light reflection type sensor, and this light reflection type sensor 16a. Is for detecting the development density, and 17a is for PCC (Pre
The PCC 17a is for removing the charge remaining on the photoconductor 7a by the brush 11a in order to make it easy to remove the toner.
8a is a light transmission type sensor, and this light transmission type sensor 18
a is for detecting the transfer paper on the transfer paper transport transfer belt 3.

Further, as shown in FIG. 3, the basic structure of the image forming apparatus of this embodiment includes a charger 8, a photoconductor 7, a developing device 9,
An image forming unit 5 having cleaning devices 11 and 12 and a static eliminator 15, an exposure device 6, a transfer device 10, and
The toner image forming signal output unit 19, the toner development control unit 20 on the photoconductor 7, the environment detection unit (detection unit for temperature, humidity, etc.) 21, and the toner image width control unit 22. The image forming unit 5,
Although the exposure device 6 and the transfer device 10 are provided for every four colors, the subscripts a, b, c, and d are omitted here for convenience.

The toner image forming signal output means 19 is provided when the color image forming apparatus is powered on or after the copying operation is completed.
The toner image forming signal is output at a predetermined time such as when the copying operation is started again after a long time has passed, and the toner developing control means 20 on the photoconductor 7 causes the toner image forming signal output means 19 to output the toner image. A toner developing signal for developing the toner on the photoconductor 7 is output at a timing at which the toner is not transferred to the transfer sheet by the image forming signal. Further, the environment detecting means 21 detects the environment such as temperature and humidity surrounding the color image forming apparatus such as a temperature detector and a humidity detector, and outputs an environment signal.
The toner image width control means 22 controls the bias potential to the developing device 9 so that the width of the toner image is determined based on the environment detection signals such as temperature and humidity from the environment detection means 21, By this control, a toner image having a width based on the environment such as temperature and humidity in the color image forming apparatus is formed on the photoconductor 7.

FIG. 4 is a diagram showing the operation timing of each component of such a color image forming apparatus. As shown in FIG. 4, when the power of the color image forming apparatus is turned on,
Alternatively, after the copying operation of the color image forming apparatus is completed, when the copying operation is performed again after a long time, the toner image forming signal output means 19 outputs the toner image forming signal to the toner developing control means 20 on the photoconductor. . As a result, the toner development control means 20 on the photoconductors is controlled by the photoconductors 7a, 7b, 7
c, 7d and the transfer sheet transporting transfer belt 3 are rotated, and when the rotation of each of the photoconductors 7a, 7b, 7c, 7d and the transfer sheet transporting transfer belt 3 is started,
After a millisecond, each charging device 8a, 8b, 8c, 8d is turned on, and each developing device 9a, 9b, 9c, 9d is biased. Thus, after 200 milliseconds, the charging devices 8a, 8b, 8c, 8d are turned on and the developing devices 9a, 9d are turned on.
The reason why the biases of b, 9c and 9d are applied is that the carrier in the developer is applied to each of the photoconductors 7a, 7b, 7c and 7d.
This is to prevent the movement to d.

Then, about 300 milliseconds after the above-mentioned reference time, each roll 9a ', 9 of each developing device 9a, 9b, 9c, 9d.
b ', 9c' and 9d 'start to rotate. Further, 800 milliseconds after the reference time, the temperature and humidity inside the color image forming apparatus are detected by the environment detecting means 21 such as the temperature detecting means and the humidity detecting means, and the toner is detected based on the detected environment such as temperature and humidity. The image width control means 22 determines the width of the toner image. That is, for example, as shown in FIG. 5, it is about 175 ms for high temperature and high humidity, about 145 ms for intermediate temperature and humidity, and 125 ms for low temperature and low temperature. The width of the toner image is set to decrease as the humidity decreases and the temperature decreases. Then, the developing bias potential is controlled so that the width of the toner image is determined. Furthermore, 125 to 17 after that
The developing bias potential is returned to the reference bias potential within 5 milliseconds to enter the copy mode.

Toners are supplied from the developing devices 9a, 9b, 9c, 9d to the latent images on the photoconductors 7a, 7b, 7c, 7d to develop the latent images, and the rotary bodies 7a, 7b, 7c are developed. , 7
Each photoconductor 7a, 7b, 7c, 7 developed by rotation of d
The toner image on d reaches the transfer position. Each photoconductor 7a,
When the toner images on 7b, 7c, and 7d reach the transfer position, the toner image width control means 22 causes the respective corotrons of the transfer devices 10a, 10b, 10c, and 10d to perform a predetermined operation about 1,500 milliseconds after the reference time. A voltage is applied, whereby the toner images on the photoconductors 7a, 7b, 7c, 7d are transferred onto the transfer paper on the transfer paper transport transfer belt 3. In that case, in each corotron of each of the transfer devices 10a, 10b, 10c, and 10d, about half of the toner image is transferred to the transfer paper transport transfer belt 3, and the remaining half of each of the photoreceptors 7a, It is operated at such a timing that it remains in 7b, 7c, and 7d.

The transfer sheet conveying transfer belt 3 and the photoconductors 7a, 7b, 7c, 7d are rotated by the rotation of the transfer sheet conveying transfer belt 3 and the photoconductors 7a, 7b, 7c, 7d.
The toner bands respectively formed on the cleaning blades reach the cleaning blades 14, 12a, 12b, 12c and 12d.
Therefore, regardless of whether writing by the ROS is enabled or disabled, the photoconductors 7a, 7b, 7c,
During the position adjustment control for controlling the surface potential and the toner concentration of 7d and the concentration adjustment control, the toner is removed by the cleaning blades 12a, 12b, 12c, 12
It will be surely supplied to d and 14. In that case, each cleaning blade 12a, 12b, 12c, 12d, 1
An optimum amount of toner is supplied between the photosensitive drum 7 and each of the photoconductors 7a, 7b, 7c, 7d based on the detected environment such as temperature and humidity in the image forming apparatus. As a result, the toner in the toner band functions as a lubricant, and between the cleaning blades 12a, 12b, 12c, 12d and the photoconductors 7a, 7b, 7c, 7d, and between the cleaning blade 14 and the transfer paper transport transfer belt 3. The lubrication between them becomes sufficient. As a result, under the high temperature and high humidity environment, the cleaning blades 12a, 12b, 12
Although the c, 12d, and 14 easily roll up, the cleaning blades 12a, 12b, 12c, 12d, and 14 can be reliably prevented from rolling up, and the toner consumption amount can be minimized. .

In the above-described embodiment, the present invention is described by being applied to a color image forming apparatus in which four developing devices and four photoconductors are arranged in tandem and the endless transfer belt 3 is provided. However, the present invention is not limited to this, and for example, four developing devices arranged on a rotating body are sequentially opposed to one photosensitive member as shown in FIG. It can also be applied to a color image forming apparatus including a transfer device. Further, it goes without saying that the present invention can be applied to other image forming apparatuses such as an image forming apparatus such as a black-and-white copying machine and a printer other than the copying machine other than the color image forming apparatus.

[0031]

As is apparent from the above description, according to the image forming apparatus of the present invention, the toner on the photoconductor is provided in an amount suitable for the cleaning blade and the photoconductor in accordance with the environment surrounding the image forming apparatus. Since it is supplied during this period, it is possible to reliably prevent the cleaning blade from curling, and it is possible to minimize the toner consumption amount for forming the toner image.

Further, since the toner image can be formed regardless of the rise of the ROS, the first transfer sheet can be brought into a state in which it can be conveyed faster than the method of forming the toner image by the ROS, and therefore the image formation can be performed. You can start quickly.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a conventional color image forming apparatus in which four color image forming units are arranged in tandem, to which an embodiment of an image forming apparatus according to the present invention is applied.

FIG. 2 is a partially enlarged detailed view of the color image forming apparatus shown in FIG.

FIG. 3 is a diagram showing a basic configuration of an embodiment of the present invention.

FIG. 4 is a diagram showing an operation timing of each component of the color image forming apparatus shown in FIG.

FIG. 5 is a diagram illustrating the relationship between temperature and humidity and the width of a toner image.

FIG. 6 is a diagram showing another example of a color image forming apparatus to which the present invention is applied.

FIG. 7 is a diagram illustrating a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Driving roll, 2 ... Followed roll, 3 ... Transfer paper conveyance transfer belt, 5,5a, 5b, 5c, 5d ... Image forming unit, 6, 6a, 6
b, 6c, 6d ... exposure device, 7,7a, 7b, 7c, 7d ... photoreceptor, 8,8a, 8b,
8c, 8d ... charger, 9, 9a, 9b, 9c, 9d ... developing device, 10, 10a, 10b, 1
0c, 10d ... Transfer device, 11, 12 ... Cleaning device, 11a, 11b, 1
1c, 11d, 13 ... Cleaning brush, 12a, 12b, 12c, 12d, 14
… Cleaning blade, 15… Erase lamp, 16
… Reflective sensor, 17… PCC (Predeaning corotoro
n), 18 ... Transmissive sensor, 19 ... Toner image forming signal output means, 20 ... Toner development control means on photosensitive member, 21
... environment detecting means such as temperature and humidity, 22 ... toner image width control means

Claims (4)

[Claims] 1. A photoconductor on which an electrostatic latent image is formed, a charger for charging the photoconductor, a developing device for developing the electrostatic latent image on the photoconductor with toner, and a charge on the photoconductor is removed. An image forming unit including a static eliminator and a cleaning device for removing foreign matter such as toner adhering to the photoconductor, and an exposure device for exposing the photoconductor to form the electrostatic latent image on the photoconductor. , A transfer device for transferring the toner image developed on the photoconductor to a transfer sheet, and a transfer device for transferring the toner image to the transfer sheet at a predetermined time such as when the power is turned on or when a re-image forming operation is started after a long time has passed after the image formation is completed. In an image forming apparatus including a toner developing control unit for developing a toner on the photosensitive member at a timing not to perform, an environment detecting unit for detecting an environment surrounding the image forming apparatus, and the timing unit. The width of the toner image in grayed, the image forming apparatus characterized by comprising a toner Zohaba control means for controlling, based on the environment of the detection the image forming apparatus by the environment detection means. 2. The image forming apparatus according to claim 1, wherein the environment is a temperature and / or humidity surrounding the image forming apparatus. 3. In the image forming apparatus, the transfer device has an endless belt-shaped transfer belt, and four developing devices and four photoconductors are arranged in tandem along the transfer belt. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color copying machine. 4. A color copying machine in which the image forming apparatus has four developing devices arranged on a rotating body opposed to one photosensitive member in order, and the transfer device has a transfer drum. The image forming apparatus according to claim 1 or 2, wherein