JP2003330232A - Image controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a good output image by eliminating swept together or inside void image and to carry out error display by detecting the end of service life of an agent. <P>SOLUTION: Being swept together and a void are improved by detecting the difference in output in an edge part of a patch image with a plane part by a patch detection sensor and the service is improved by carrying out error display due to service life of the agent when a compensating value exceeds a limit value. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image control method for copying machines and printers.

[0002]

2. Description of the Related Art Various types of electrophotographic full-color printers and full-color copying machines have been proposed. However, from the viewpoint of downsizing of the apparatus and sharing of developing devices for respective colors, the photosensitive drum is commonly used. It is advantageous to mechanically move each developing device to sequentially face the photosensitive drum. Further, the moving method of the developing device is roughly divided into a slide type and a rotating type, but a method using a system in which the developing device is housed in a rotating body and the developing device is moved by rotation of the rotating body is used. As compared with, for example, a device in which the developing device is slid in a linear direction, it is not necessary to secure a space for movement, which is advantageous in downsizing of the device. FIG. 12 shows an example of a full-color image control method using such a rotating body type developing device. In FIG.
The developing device 102Y contains a two-component developer composed of a non-magnetic toner and a magnetic carrier, and has a developing sleeve 105Y as a developer conveying means and an optical sensor 107Y for detecting the mixture ratio of the developers. The developing device 102M and the developing device 102C have the same configuration as the developing device 102Y. Developing device 102Y, developing device 102M, developing device 102C
Respectively contain yellow, magenta and cyan toners. Further, these developing devices 102 are provided with a rotating body 106.
The photosensitive drum 128, which is an image carrier, is sequentially opposed by rotation of the rotating body 106.

Developing sleeve 10 made of a non-magnetic material
5 is rotatable and has a magnet inside. The developing sleeve 105 carries and conveys the two-component developer to the developing area by the rotational force and the magnetic force of the magnet, supplies the developer to the photosensitive drum 128 in the developing area facing the photosensitive drum 128, and is formed on the photosensitive drum 128. To develop the electrostatic latent image.
When the toner is consumed by the image formation, the toner density of the two-component developer is lowered and the image density is lowered. For this reason,
The developing device using the two-component developer as in the conventional example is provided with a mechanism for detecting the toner concentration of the two-component developer and supplying an appropriate amount of toner.

Generally, as a method of detecting the toner density,
There is a method in which the developer is directly detected by a change in physical properties of the two-component developer itself, such as a change in reflection density or a change in magnetic permeability. Further, a method is used in which the reference latent image on the photosensitive drum 128 is developed to form a toner patch, and the reflection density of the toner patch is detected by the optical sensor 101.
This is because the development characteristic of the latent image on the photosensitive drum 128 changes due to the decrease in the toner density. There are various methods for forming the reference latent image, but in the digital image control method, it is general that the reference latent image is formed by performing a predetermined exposure with an exposure device such as a laser or an LED which is an image exposure means. Is.

In such a system, since the object of detection is only the amount of toner developed on the photosensitive drum 128, the toner density is not directly controlled, to be exact. In fact, if there are fluctuations in the toner patch reflection density due to factors other than toner density fluctuations, such as changes in the ambient temperature and humidity, and long-term use of the two-component developer, the actual toner density of the two-component developer will not It will be touched within a certain range by absorbing the factors. However, the toner density of the two-component developer does not have to be constant at all times, and if it is within a predetermined range with respect to the initial center value, using auxiliary means such as gradation control causes a serious problem. It is possible to output an image without causing There is also one that uses this reflection density system as means for this gradation control. An optical sensor detects the amount of reflected light from a patch image formed on the photosensitive drum or transfer drum and that has different laser levels, and feedback is applied to a look-up table to control the amount of toner adhesion from that value, and the gradation is improved. Are controlled to keep.

[0006]

Due to the deterioration of the developer, the toner on the edge of the image end portion is excessively deposited on the flat surface portion (hereinafter, referred to as sweeping), or the toner is not deposited (hereinafter,
It is called a blank area.

This will be described with reference to FIG. The output of the sensor 1 when a test patch of a predetermined level is formed on the photosensitive drum 28 is shown. The solid line a is the output value in the normal state like the initial agent.
The dotted line b is the sensor output value in image formation when the deterioration of the developer is promoted. If the developer is in a normal state as indicated by the solid line a, the edge portion (points c and d) of the image formation and the flat portion (section x
The image density is uniform without the boundary of -y), and the output value of the sensor 1 is also a uniform value. However, when the deterioration of the developer is promoted, the charge distribution of the toner in the developer is reduced as shown by the dotted line b, and the charge of the photosensitive drum is more likely to be drawn, and the toner is transferred to a portion where the potential difference from the photosensitive drum is large. Are attracted, the toner is concentrated on the edge portions (points c and d), and a density difference (sensor output value difference) with respect to the flat surface portion (section xy) occurs. When continuously forming images having different densities as shown in FIG. 6, the toner that should have been placed on the point d1 of the low density portion is attracted to the edge point d2 of the high density portion.
2) will occur.

[0008]

[Means for Solving the Problems] That is, an image carrier for carrying an electrostatic latent image, and a charging means for charging the image carrier,
A developing unit for developing the electrostatic latent image on the image carrier, a transferring unit for transferring the toner image on the image carrier, and a density detecting device for detecting the amount of reflected light of the toner image by an optical sensor, In an image control method for forming a predetermined test pattern on the image carrier, detecting the toner image of the test pattern by the density detecting device, and correcting the image forming conditions,
An image control method characterized by detecting the edge portion of the toner image formed by the developing means by the density detecting device and correcting the image forming condition according to the detection result, an image carrying an electrostatic latent image A carrier, a charging unit that charges the image carrier, a developing unit that develops an electrostatic latent image on the image carrier, a transfer unit that transfers a toner image on the image carrier, and a transfer unit that transfers the toner image. A transfer carrier for carrying the toner image, and a density detecting device for detecting the amount of reflected light of the toner image by an optical sensor, and forming a predetermined test pattern on the image carrier,
In the image control method of detecting the toner image of the test pattern by the density detecting device and correcting the image forming condition, the toner image formed by the developing device is carried on the transfer carrier to obtain the toner image of the toner image. An image control method characterized by detecting the edge portion by the density detection device and correcting the image forming condition according to the detection result, thereby sweeping and obtaining a good output image without a blank image It is possible to detect an appropriate life of the developer, display an error message, and improve serviceability.

[0009]

Embodiment 1 Hereinafter, a first embodiment of an image control method according to the present invention will be described with reference to the accompanying drawings.

First, the operation of the entire image control method will be described with reference to FIG.

In FIG. 1, a developing device 2 in which yellow, magenta, and cyan toners are contained in a rotating body 6 is shown.
Y, 2M, and 2C are accommodated, and one of the three developing devices 2 described above is rotated by the rotation of the rotating body 6 to the photosensitive drum 2.
Face 8 The photosensitive drum 28, which is an image carrier, is rotatably provided. The photosensitive drum 28 is uniformly charged by the primary charger 21, and is exposed by the light whose exposure amount is adjusted by the laser 22. To form a yellow electrostatic latent image. The electrostatic latent image of yellow is visualized as a toner image on the photosensitive drum 28 by a process described later by using the developing device 2Y containing yellow toner. Next, the visible image is transferred by the transfer charger 23 onto the transfer paper 24 conveyed by the transfer paper conveying sheet 27. The transfer residual toner on the photosensitive drum 28 is removed by the cleaning device 26. The photosensitive drum 28 thus cleaned is charged by the primary charger 21 again,
It is exposed by the laser 22 to form a magenta electrostatic latent image. When this electrostatic latent image passes through the developing area, the developing device 2M containing the magenta toner is opposed to the photosensitive drum 28 by the rotation of the rotating body 6, and therefore, the magenta electrostatic latent image is formed by using this. Development is performed to obtain a magenta toner image. This toner image is transferred onto the transfer paper 24 onto which the yellow toner image has been transferred. In this manner, yellow, magenta, and cyan toner images are sequentially formed on the transfer paper 24, and then fixed by the fixing device 25 to obtain a full-color image. Timing of each operation,
Control, reading signals from sensors, etc.
It is performed by the control device 30.

Next, the developing device 2 will be described in detail. The developing sleeve 5 made of a non-magnetic material is rotatable, and when the rotating body 6 rotates to reach a position for developing an electrostatic latent image, it is exposed to light. It faces the drum 28. Development sleeve 5
A magnet is built in the inside of the drum, and the two-component developer is carried and conveyed to the developing area by the rotational force and the magnetic force of the magnet, and the developer is transferred to the photosensitive drum 2 in the developing area facing the photosensitive drum 28.
8 to develop the electrostatic latent image formed on the photosensitive drum 28.

The photosensitive drum 2 is located on the downstream side in the rotating direction of the photosensitive drum from the portion where the developing device 2 and the photosensitive drum 28 face each other.
The optical sensor 1 is arranged so as to oppose to 8. FIG. 10 shows a schematic enlarged view. The optical sensor 1 includes a photosensitive drum 28.
The light-emitting element 1a such as an LED irradiates the photosensitive drum 28 with the reflection density of the toner patch formed by developing the reference latent image of the above predetermined test pattern, and the reflected light is received by the light-receiving element 1b to obtain a / After conversion by the d converter 29, the CPU
Are captured and processed, and the toner density is controlled within a predetermined range by detecting the reflection density, and in addition to the toner patch for toner density control, a plurality of gradation patches formed by changing the exposure amount in several steps It is also used for the purpose of detecting the reflection density of the light and correcting the look-up table of the exposure amount control signal of the light emitting element for the image information.

The operation of detecting the signal of the toner patch for controlling the toner density and replenishing the toner will be described in detail. The reference latent image is formed by charging the photosensitive drum 28 to a predetermined potential by the charger 21, predetermined exposure by the laser 22, and developed by the developing device 2. When the toner patch formed in this way reaches the facing portion of the optical sensor 1, the light having a wavelength of about 960 nm emitted from the light emitting element 1a in the optical sensor 1 is reflected by the toner patch, and the light received in the optical sensor 1 is received. It reaches the element 1b, and the output voltage V
To get

FIG. 2 is a development view of the photosensitive drum and is an image diagram showing detection of a patch image formed on the photosensitive drum. The photosensitive drum 28 moves in the direction of arrow A.
After the image forming sequence operation is started, the toner amount is detected by the sensor 1 from the predetermined position a on the photosensitive drum 28. The operation of the developing means is started from the point b, and the toner amount of fog is detected. A patch image having a predetermined density is formed between points c and d, the developing operation is completed at point e, and the detection by the sensor 1 is completed at point f. The signal detected by the sensor 1 is A / D converted by the A / D converter 29 and processed by the control device 30.

FIG. 3 is an image diagram showing the signal read by the sensor 1 on the time axis.

The solid line is the sensor output of the developed image in the initial developer, and the dotted line is the sensor output of the developed image in the deteriorated developer after running. Although the density of the predetermined image is detected in the section c-d, the toner is concentrated at the edge portions of the points c and d, and the applied amount is increased. Since the toner amount and the sensor output can be uniquely determined, the difference between the sensor outputs becomes the toner amount difference. This sensor output difference is ΔV1. The initial data (the solid line in FIG. 3) of the patch control image in the initial developer is backed up. Vab is a photosensitive drum detection, Vbc is a fog toner detection, Vc is a leading edge detection, Vxy is a density detection, Vd.
Is the trailing edge detection. On the other hand, when various conditions of the main body are changed due to changes in durability, environmental changes, etc., an image is formed so as to obtain the same output at a predetermined timing, and the sensor output is obtained. Vab ', Vbc', V (indicated by the dotted line in FIG. 3)
c ′, Vxy ′ and Vd ′. ΔV1 can be compared with ΔV1 ′ after the endurance by normalizing the predetermined patch density. The two signals ΔV1 and ΔV1 ′ are compared, the comparison value α is fed back to the image forming condition, here, the development dc bias value, and the feedback amount is determined by the comparison value α to improve the sweeping. You can

A test pattern as shown in FIG. 4 is formed for each color to detect a swept image. FIG. 5 shows the sensor output of the image density when the development dc value is variable.

[0019] indicates the concentration fluctuation due to the sensor output in the initial state. In this state, there is almost no sweeping of the edge portion, which is a good image state. Is the sensor output due to the deteriorated developer after endurance. In this state, the toner concentrates on the edges, the density becomes non-uniform, and the swept image is conspicuous. Is the sensor output when the development dc value is changed in the above state to reduce the fog removal potential (the potential difference between the photosensitive drum potential and the development dc potential). In this state, the correction effect appears and the sweeping is reduced. Is the sensor output when the fog removal potential is further reduced in order to further accelerate the deterioration of the developer and improve the sweeping. As the developer deteriorates, the swept image is promoted, and the image can be improved by decreasing the fog removal potential, but the background fog on the white background is likely to occur. The correction amount at which the ground fog occurs is the limit value of the correction amount. Also,
When ΔV1 ′ exceeds a predetermined value β, it is determined that it is difficult to improve the level of sweeping, it is determined that the developer has reached the end of life, and an error message is issued to prompt replacement of the developer. As a result, the swept image can be improved, good image quality can be obtained, the optimum replacement time of the developer can be obtained by a message, and serviceability can be improved.

In this example, it has been described that the development dc value is corrected and the swept image is improved. However, the same effect can be obtained even if the development AC bias value or the charging potential, which is another image forming condition. You can get it.

Embodiment 2 FIG. 6 is a development view of a photosensitive drum and is an image diagram showing detection of a patch image formed on the photosensitive drum. The photosensitive drum 28 moves in the direction of arrow A. After the image forming sequence operation is started, the toner amount is detected by the sensor 1 from the predetermined position a on the photosensitive drum 28. The operation of the developing means is started from the point b, and the toner amount of fog is detected. A patch image having a predetermined density is formed between points c and d and points d and e, the developing operation ends at point f, and the detection by the sensor 1 ends at point g.

The signal detected by the sensor 1 is A / D converted by the A / D converter 29 and processed by the controller 30. FIG. 7 is an image diagram showing a signal read by the sensor 1 on a time axis.

The solid line is the sensor output of the developed image in the initial developer, and the dotted line is the sensor output of the developed image in the deteriorated developer after running. The density detection (low density portion and high density portion) of a predetermined image is performed in the sections c-d and the section d-e, but toner is concentrated at the edge portions of the points c, d1, and e, and the applied amount is increased. . Further, at the point d2, the toner that should be placed on the edge of the low density portion is attracted to the drum potential of the high density portion, and the toner is concentrated on the edge of the high density side, causing white spots. Since the toner amount and the sensor output can be uniquely determined, the difference between the sensor outputs becomes the toner amount difference. This sensor output difference is ΔV1, Δ
Let V2 and ΔV3. The initial data (indicated by the solid line in FIG. 7) of the patch control image in the initial developer is backed up. Vab is the photosensitive drum detection, Vb
c is fog toner detection, Vc is tip swept detection, Vh
i and Vjk are density detection, Ve is rear edge sweep detection, Vd
Indicates white spot detection. On the other hand, when various conditions of the main body are changed due to changes in durability, environmental changes, or the like, images are formed so as to obtain the same output at a predetermined timing, and the sensor output is obtained. ΔV1 and ΔV2 can be compared with ΔV1 ′ and ΔV2 ′ after the endurance by standardizing a predetermined patch density.

This signal is compared, and if the respective comparison values are α and β, the comparison values α and β are fed back to the image forming conditions, here the development dc bias value, and sweeping and white spots are improved. You can

A test pattern as shown in FIG. 8 is formed for each color to detect a swept image. FIG. 9 shows the image density sensor output when the development dc value is variable.

[0026] indicates the concentration fluctuation due to the sensor output in the initial state. In this state, there is almost no sweeping of the edge portion, which is a good image state. Is the sensor output due to the deteriorated developer after endurance. In this state, the toner concentrates on the edges, the density becomes non-uniform, and the toner is swept away, and a blank image becomes conspicuous.
Is the sensor output when the development dc value is changed in the above state to reduce the fog removal potential (the potential difference between the photosensitive drum potential and the development dc potential). In this state, the effect of correction appears, and sweeping and white spots decrease. Is the sensor output when the fog removal potential is further reduced in order to further accelerate the deterioration of the developer, and to improve the whiteout image. As the deterioration of the developer progresses, the image is swept away and a blank image is promoted, and the image can be improved by decreasing the fog removal potential, but the background fog on the white background is likely to occur. The correction amount at which the ground fog occurs is the limit value of the correction amount.

Further, the comparison values ΔV1 'and ΔV2' are predetermined values γ.
When it exceeds the limit, it is determined that it is difficult to improve the level of a blank image, it is determined that the developer has reached the end of life, and an error message is issued to prompt replacement of the developer.

As a result, it is possible to improve the swept-out and white-blank image, obtain a good image quality, obtain the optimum time for replacing the developer by a message, and improve the serviceability.

In this example, it is explained that the development dc value is corrected and swept to improve the blank image, but the development AC bias value, the charging potential, the development sleeve-sensitivity which are other image forming conditions. The same effect can be obtained by feeding back the distance between the drums (SD distance).

Further, in a four-drum system using an intermediate transfer pair as shown in FIG. 11, even if a sensor is arranged so as to detect the detection image transferred on the intermediate transfer body, the same effect can be obtained. Can be done.

[0031]

As described above, the image carrier for carrying the electrostatic latent image, the charging means for charging the image carrier, and the developing means for developing the electrostatic latent image on the image carrier. A transfer unit for transferring the toner image on the image carrier, and a density detection device for detecting the amount of reflected light of the toner image by an optical sensor,
A predetermined test pattern is formed on the image carrier, and the toner image of the test pattern is detected by the density detecting device,
An image control method for correcting an image forming condition is characterized in that an edge portion of a toner image formed by the developing means is detected by the density detecting device, and the image forming condition is corrected according to a detection result. Image control method, image bearing member carrying an electrostatic latent image, charging means for charging the image bearing member, developing means for developing the electrostatic latent image on the image bearing member, and on the image bearing member A transfer unit for transferring the toner image, a transfer carrier for carrying the transferred toner image, and a density detecting device for detecting the reflected light amount of the toner image by an optical sensor,
A predetermined test pattern is formed on the image carrier, and the toner image of the test pattern is detected by the density detecting device,
In an image control method for correcting an image forming condition, a toner image formed by the developing means is carried on the transfer carrier, and an edge portion of the toner image is detected by the density detecting device, and a detection result is detected. The image control method is characterized in that the image forming condition is corrected according to the image forming condition, and it is possible to obtain a good output image without white spots by sweeping, and an error is detected by detecting the proper life of the developer. A message can be displayed and serviceability can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram illustrating an image control method according to a first embodiment of the present invention.

FIG. 2 is a development view of the photosensitive drum showing image formation according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a sensor output according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an image forming pattern according to an embodiment of the present invention.

FIG. 5 is a diagram showing sensor output in the image control method according to the first embodiment of the present invention.

FIG. 6 is a development view of a photosensitive drum showing image formation according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a sensor output according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating an image forming pattern according to a second embodiment of the present invention.

FIG. 9 is a diagram showing sensor output in the image control method according to the second embodiment of the present invention.

FIG. 10 is a diagram illustrating a reflected light amount detection sensor.

FIG. 11 is a configuration diagram of a main body showing another embodiment.

FIG. 12 is a diagram illustrating an image control method according to a conventional example.

[Explanation of symbols]

1. Optical sensor 1a. Light emitting element 1b. Light receiving element 2. Development device 3. Toner supply tank 4. Toner supply screw 5. Development sleeve 21. Primary charger 22. laser 23. Transfer charger 24. Transfer paper 25. Fixing device 26. Cleaning device 27. Transfer paper transport sheet 28. Photosensitive drum 29. A / D converter

Claims (6)

[Claims] 1. An image bearing member carrying an electrostatic latent image, charging means for charging the image bearing member, developing means for developing the electrostatic latent image on the image bearing member, and on the image bearing member. The transfer means for transferring the toner image and the density detecting device for detecting the reflected light amount of the toner image by the optical sensor, forming a predetermined test pattern on the image carrier, and transferring the toner image of the test pattern. In an image control method of detecting with a density detecting device and correcting the image forming condition, the edge portion of the toner image formed by the developing unit is detected with the density detecting device, and the image forming condition is corrected according to the detection result. An image control method comprising: 2. The image control method according to claim 1, wherein the image forming condition is corrected by comparing the output value of the density detecting device of the edge portion of the predetermined test pattern and the flat portion. 3. The predetermined test pattern comprises a plurality of different test patterns, and compares the output values of the density detecting device during non-image formation of the developing means, during white background image formation and during patch image formation. The image control method according to claim 1, wherein the image forming condition is corrected. 4. An image bearing member carrying an electrostatic latent image, charging means for charging the image bearing member, developing means for developing the electrostatic latent image on the image bearing member, and on the image bearing member. The transfer means for transferring the toner image and the transfer carrier for carrying the transferred toner image, and the density detecting device for detecting the amount of reflected light of the toner image by the optical sensor are provided on the image carrier. In an image control method of forming a predetermined test pattern, detecting the toner image of the test pattern by the density detecting device, and correcting the image forming condition, the toner image formed by the developing means is transferred onto the transfer carrier. And an edge portion of the toner image is detected by the density detecting device, and the image forming condition is corrected according to the detection result. 5. The image control method according to claim 4, wherein the image forming condition is corrected by comparing the output value of the density detecting device of the edge portion of the predetermined test pattern and the flat portion. 6. The predetermined test pattern is composed of a plurality of different test patterns, and compares the output values of the density detecting device during non-image formation of the developing means, during white background image formation, and during patch image formation. The image control method according to claim 4, wherein the image forming condition is corrected.