JPH1090960A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that the premise that toner adhesion quantity can be changed by the rotating speed control of a developing sleeve according to the detection result of a patch image can not be provided by determining the circumferential speed ratio of a developer carrying carrier on the basis of the detected value corresponding to the toner adhesion quantity and the circumferential speed ratio in the development of the patch image. SOLUTION: When the potential of a charged surface by a charging means or a developer used for developer carrying carrier is binary, one or both of toner densities of the developer are regulated, whereby a patch image is formed to determine the detected value by a detecting sensor. For example, prior to the formation of a recording image, a patch image for providing the toner adhesion quantity of the highest density part of each color toner image is formed on the surface of the rotating image carrier 1, and the toner image adhesion quantity is detected by a detecting sensor 9 and a detecting circuit 10, whereby the detection information is provided. On the basis of the detection result, the circumferential speed ratios to the image carrier 1 of the developing sleeves of developing equipments 3Y-3BK in image recording are determined.

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 using an electrophotographic method, and more particularly to a method for controlling the amount or density of a toner image formed on an image carrier to achieve clear recording. The present invention relates to a technique for stably forming an image.

[0002]

2. Description of the Related Art In recent years, an image forming apparatus using a digital system and reversal development has been put into practical use. For example, a color image recording apparatus constituting an output section of a color electrophotographic copying machine, a personal computer, a facsimile or the like is known. . In such an image forming apparatus, even during continuous operation, it is necessary to perform an adjustment operation in order to obtain a recorded image with good reproducibility, but the adjustment operation is complicated and troublesome.

In order to solve the problem, Japanese Patent Application Laid-Open
An image control technique based on a patch detection method as described in JP-A-113568 is employed. The technology is based on a prior art that before forming a recorded image on a photosensitive drum serving as an image carrier, a gradation density for each color component color such as yellow (Y), magenta (M), cyan (C) and black (BK). A pattern is formed, the density of the pattern is measured by a detection sensor, a correction amount is obtained, and the exposure amount by a laser beam or the like for forming an electrostatic image in the subsequent formation of a recorded image is corrected based on the correction amount. This is to control and adjust the density. However, there is a problem that the type and quantity of the measurement data of the density pattern for each color constituting color become enormous, a program relating to the density adjustment becomes complicated, it takes time until the adjustment, and the design cost becomes too enormous.

In order to solve the above problem,
A control coefficient for correction is read out from a memory so as to control the amount of toner adhered in accordance with a change in detection data of a toner image (hereinafter, also referred to as a patch image) of a reference image serving as a density reference, and the developer transfer carrier carries the correction coefficient. A technique for feedback-controlling the rotation speed of a developing sleeve has also been developed (Japanese Patent Application No. Hei 6-189221). In this technology, the photosensitive speed is reduced by reducing the number of revolutions of the developing sleeve to one-third of that in the recording image mode so that the value of the detection signal falls within a stable region excluding an unstable region which is a problem in the characteristics of the detection sensor. Reduce the amount of toner attached to the color patch image to the body drum to about 1/3,
By detecting the patch image, the deviation amount from the reference toner adhesion amount is accurately recognized, and based on the relationship between the rotation speed of the developing sleeve and the toner adhesion amount of the photosensitive drum, the toner adhesion amount when forming an image on a recording medium. And the ratio of the peripheral speed of the developing sleeve to the constant peripheral speed of the photosensitive drum is controlled in accordance with the rotational speed of the developing sleeve.

Further, by proceeding with the above-described technique, an estimation calculation is performed in consideration of the saturation characteristic of the toner adhesion amount with respect to the peripheral speed ratio and the change in the toner adhesion amount due to the aging of the photosensitive drum, thereby accurately predicting the toner adhesion amount. A technique for performing the technique has also been developed, and the technique has been filed as Japanese Patent Application No. 6-280719.

Further, the detection result of the patch image is controlled so that the toner adhesion amount can be controlled more stably by controlling the rotation speed of the developing sleeve, excluding the influence of the fluctuation of the detection result due to the position where the patch image is formed on the photosensitive drum. It has also been devised to use a value of the ratio of the output of the detection sensor for detecting the patch image to the output of detecting the surface of the photosensitive drum near the patch image.

[0007]

The image control technique based on the control of the number of rotations of the developing sleeve is based on the premise that the toner adhesion amount can be changed by controlling the number of rotations of the developing sleeve based on the detection result of the patch image. It stably realizes the necessary amount of toner adhered during recording and forms a clear toner image.It is unlikely that the premise will be maintained, but still, the photoconductor drum and the carrier of the two-component developer deteriorate and the If the environmental conditions, such as temperature and humidity, and dirt change significantly, the assumption cannot be obtained, and the required maximum toner adhesion amount cannot be obtained, resulting in the formation of unclear toner images. Toner adhesion exceeding the toner adhesion amount occurs, resulting in the formation of an image with poor gradation, or contamination in the machine or excessive consumption of the developer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and it is possible to prevent the assumption that the toner adhesion amount can be changed by controlling the rotation speed of the developing sleeve according to the detection result of the patch image. Therefore, the maximum amount of toner adhesion required by controlling the number of rotations of the developing sleeve can be stably realized, and an image forming apparatus capable of forming a clear toner image. It is an object of the present invention to provide an image forming apparatus that prevents formation of a poorly adjusted image and occurrence of contamination in the apparatus.

[0009]

According to the present invention, there is provided a charging means for uniformly charging the surface of an image carrier around an image carrier, and an image exposure device for irradiating an image on a charged surface. An exposure unit for forming an electrostatic image by developing the electrostatic image into a toner image; a developing unit including a developer carrying carrier for developing the electrostatic image into a toner image; and a developing unit for detecting the amount of adhesion or density of the toner image on the image carrier. A detection sensor, and detects a patch image, which is a toner image of a reference image formed in advance on the surface of the rotating image carrier, with the detection sensor to obtain a detection value corresponding to the toner adhesion amount of the patch image. An image forming apparatus that determines the peripheral speed ratio of the developer transport carrier for forming a toner image during recording image formation based on the peripheral speed ratio of the developer transport carrier having developed the patch image to the image carrier. And the detection value and the patch image are developed. When the calculated value corresponding to the peripheral speed ratio obtained from the speed ratio and the change ratio of the toner adhesion amount deviates from a predetermined range, the developer conveying carrier of the image recording mode in the image recording mode is determined based on the detected value and the peripheral speed ratio. Without determining the peripheral speed ratio,
If the potential of the charged surface by the charging means or the developer used for the developer carrying carrier is a two-component, one or both of the toner concentrations of the developer are adjusted, and thereby, again. A patch image is formed on the surface of the image carrier, detected by a detection sensor, a detection value corresponding to the toner adhesion amount of the patch image is obtained, and the calculated value obtained from the detection value and the peripheral speed ratio of the developed patch image is calculated. A configuration in which the peripheral speed ratio of the developer transporting carrier in the image recording mode is determined based on the detected value and a peripheral speed ratio obtained by developing the patch image when the peripheral speed ratio is within the predetermined range; or Item 2
The number of rotations of the developer transport carrier according to the patch image detection result, wherein the detection sensor irradiates the light of the light emitting element to the image carrier surface and receives the reflected light by the light receiving element. Thus, it is possible to achieve the object of providing an image forming apparatus in which it is possible to prevent the assumption that the toner adhesion amount can be changed.

Further, when the calculated value deviates from a predetermined range, the potential of the charged surface by the charging means is changed within a predetermined range, and when the calculated value is changed within the predetermined range, the calculated value obtained again is changed. 5. The method according to claim 4, further comprising a step of forming a toner image of the recorded image based on predetermined toner image forming conditions or displaying a warning and stopping the rotation of the image carrier when the value does not fall within the predetermined range. When the calculated value is out of a predetermined range, the potential of the charged surface by the charging means is changed within a predetermined range. When the developer used for the developer carrying carrier is a two-component developer, the toner concentration of the developer is changed stepwise within a predetermined range, and when the change is within the predetermined range, the calculated value obtained again is within a predetermined range. Places that do not enter 6. The method according to claim 5, further comprising a step of forming a toner image of the image recording based on predetermined toner image forming conditions or displaying a warning and stopping rotation of the image carrier. By adding a configuration in which the image forming condition is a toner image forming condition using the peripheral speed ratio of the image recording mode determined based on the latest detected value and the peripheral speed ratio of the patch image developed, An image forming apparatus that prevents the formation of poor gradation images and the occurrence of contamination in the machine when it is no longer possible to change the toner adhesion amount by controlling the number of rotations of the developer conveyance carrier according to the detection result of a patch image Achieve the purpose of the offer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention, FIGS. 2 and 3 are use state diagrams and circuit diagrams showing an example of a toner image detection sensor, and FIGS. FIG. 6 is a side view of the image carrier showing the surface of the image carrier with respect to adjustment and detection results of the sensor, and an output voltage graph of the detection sensor. FIGS. 6 to 9 are flowcharts each showing an example of image forming condition control by the control unit of FIG. FIG. 10 is a graph showing the relationship between the patch image toner adhesion amount and the relative output of the detection sensor, and FIG. 11 is a graph showing the relationship between the peripheral speed ratio of the developer carrying carrier to the image carrier and the patch image toner adhesion amount.

The image forming apparatus shown in FIG. 1 has a charger 2 of a scorotron corona discharger for uniformly charging the surface of an image carrier around an image carrier 1 of a drum-shaped photosensitive member which rotates in the direction of an arrow. An image exposure comprising a semiconductor laser, a beam expander, a scanning deflecting means such as a polygon mirror and a galvano mirror, an fθ lens, a cylindrical lens, a mirror, etc., which form an electrostatic latent image having a distribution of low potential dots upon incidence of image exposure. Means 22, and a Y toner for the developer,
Using M toner, C toner, and BK toner, the toner flies from the developer layer formed on the developer carrying member in a non-contact manner with the image carrier surface and adheres to the low potential dot of the electrostatic latent image. Developing units 3Y, 3M, 3C for performing contact reversal development;
3BK and the transfer paper fed from a transfer paper supply unit (not shown) are pressed against the image carrier surface, and a transfer bias voltage having a polarity opposite to that of the image carrier surface and the toner charge is applied to the toner image on the image carrier surface. Roller 4 for transferring the image onto transfer paper
And the transfer paper on which the toner image has been transferred is neutralized to remove the image carrier 1
Static elimination brush 5 separated from the surface of FIG.
As shown in (1), a light emitting element 91 such as an LED for obtaining detection information corresponding to the amount of adhered toner by projecting light onto the surface of the image carrier 1 or a toner image formed on the surface to measure the amount of reflected light, and a phototransistor And a cleaning device 6 for cleaning the surface by bringing a blade 61 for scraping residual toner into contact with the surface of the image carrier 1 after the transfer of the toner image. ing.

The image forming apparatus is driven under the control of the control unit 8 so that the surface of the image carrier 1 is Y, M,
By forming a toner image of any one of C and BK, a color image composed of a plurality of toner images of up to four colors superimposed can be formed. This is a color image forming apparatus that performs recording by fixing by a fixing device using an overheated pressure roller or the like shown in the figure. In order to stably form a clear color image with good color balance, it is necessary to obtain the toner adhesion amount of the highest density portion of each color toner image on the surface of the rotating image carrier 1 prior to the formation of the recording image. Form a patch image,
Detection information is obtained by detecting the amount of toner image adhesion by the detection sensor 9 and the detection circuit 10, and based on the detection result, the circumference of the developing sleeve 30 of the developing devices 3Y to 3BK with respect to the image carrier 1 when recording images. The speed ratio is determined.

As shown in FIG. 2, a detection sensor 9 provided between the neutralizing brush 5 and the cleaning unit 6 is provided with a light emitting element 91 and a light receiving element 92 as shown in FIG. Make an angle of 40 ° on each side with respect to the normal line of the image carrier 1, and the distance from the surface of the image carrier 1 to the surface of the light emitting element 91 and the light receiving element 92 of the optical axis is respectively It is arranged to be 6 mm. Then, as shown in FIG. 3, the light emitting element 91 is driven by the driving voltage VLE.
D is applied and a current based on the resistance 11 of 1.5 kΩ is passed to emit a constant amount of light having a wavelength of 570 nm toward the surface of the image carrier 1, and the light receiving the reference voltage VCC applied to the emitter When the element 92 receives the light reflected from the image carrier 1 as a base, a current proportional to the amount of received light flows through the collector, and a variable voltage determined by the ratio between the resistor 12 such as 36 kΩ and the resistor 13 such as 68 kΩ is used as an OP amplifier. 16 and is amplified at a gain determined by the resistor 14 such as 560 kΩ and the resistor 15 such as 36 kΩ, and the surface of the image carrier 1 before the formation of the patch image, the surface of the patch image, and the vicinity of the patch image, respectively. Output voltages V1 ', V2, and V1 are output to the control unit 8 as detection signals corresponding to the amounts of light reflected from the front and rear surfaces of the image carrier 1.

The controller 8 determines the peripheral speed ratio of the developing sleeve 30 as follows.

In response to a start signal from an operation panel (not shown), the image carrier 1 is rotated in the direction of the arrow in FIGS. 1 and 4, and its surface is cleaned by the action of the blade 61 of the cleaning device 6, and its surface is cleaned. Of the light emitting element 91 so that the output voltage V1 'shown in FIGS. 3 and 5 of the intensity of the reflected light by the detection sensor 9 shows an appropriate average value of a variation within ± 5%, preferably ± 2% of the average value. Determine the drive voltage VLED. This is the detection sensor light emission adjustment step in the flowcharts of FIGS. Regardless of this, the light emitting element 9
One drive voltage VLED may be set to an appropriate constant value in advance.

Next, the latest history of image forming conditions other than the image exposure written in the memory 21 using the nonvolatile memory which can rewrite data at any time, or the memory 2
When the image forming condition has not been written in the memory 1, the image forming condition as an initial value is read from the memory 7 using the nonvolatile memory, and the image exposure condition including the patch image data is read from the memory 7. The charger 2, the image exposing means 22, and the developing devices 3 Y to 3 BK are driven according to the image forming conditions to form Y to BK patch images on the surface of the image carrier 1. It is needless to say that this patch image is formed for each rotation of the image carrier 1 so as not to overlap, similarly to the constituent color toner image of the recorded image. Further, unlike the example of FIG. 1, the color image forming apparatus includes the same number of charging devices and image exposure units as the number of developing devices, and superposes a plurality of toner images within one rotation of the image carrier. Needless to say, the patch images BK to BK are also formed so as not to overlap within one rotation of the image carrier.

When forming a patch image, the following image forming conditions are used as initial values, that is, the uniform charging potential VH = -750 V of the image carrier 1 by the charger 2, and the image exposure means 22.
Image exposure conditions including patch image data giving a constant value within the range of VL = -40 to -50 V of the writing potential according to
Surface speed 7 of developing sleeve 30 which is a developer carrying carrier
0 mm / sec or a peripheral speed ratio R = 0.7 mm with respect to the image carrier surface speed of 100 mm / sec, the amount of developer transport of the developing sleeve 30 is 20 to 30 mg / cm ² , and the DC of the developing sleeve 30 is
The bias voltage VDC = −650 V, the AC bias voltage VAC = 1.7 kVP-P (frequency 8 kHz), the toner concentration Tc = 9 wt% when a two-component developer is used, and the like are stored in the memory 7. These image forming conditions are written into the memory 21 as usage history conditions when used for image formation, separately from the patch image data, and are stored in the memory 21 when changed and used for patch image formation as described later. The changed condition is written in place of the above condition.

When the patch image is formed, the output voltage V1 due to the reflected light in the neighboring area and the output voltage V2 due to the reflected light of the patch image are determined for each patch image by the detection sensor 9 and the detection circuit 10 whose light emission has been adjusted. And V1 and V
2, a detection value D = V2 / V1 corresponding to the toner adhesion amount is obtained. Note that the detection value D is not limited to the above-described example.
= V2 / V1 'or D = V2. Needless to say, it is preferable that V1 ', V1, and V2 used for obtaining D are average values in which fluctuations are averaged.

The toner adhesion amount Mmg / cm ^{2 of the} patch image
Conditions but in the stable region for example, excluding the unstable region of 0.1 mg / cm ² and less than 0.3 mg / cm ² exceeded shown in FIG. 10 as a characteristic problem of the detection sensor, i.e. the detected value D is toner adhesion The condition D1 ≧ D ≧ D2 within the range given by the detection value D1 when the amount is 0.1 mg / cm ² and the detection value D2 when 0.3 mg / cm ² is satisfied, and the toner adhesion amount Mmg / cm ^The peripheral speed ratio R of the developing sleeve 30 that has developed the ^second patch image to the image carrier 1 and the constant toner adhesion amount within a stable area, which is used as the toner adhesion amount of the patch image, for example, 0.1 mg / cm ² . 0.3 mg / cm ²
The reference amount of adhesion M0m, which is 0.2 mg / cm ² of the average
g / cm ² , R0 = R × (M0 / M).
/ Cm ² , and a gradient peripheral speed ratio R0 which is also a value indicating a gradient of a change in the peripheral speed ratio R with respect to a change in the amount of adhered toner, as shown in FIG. When the condition of R1 ≦ R0 ≦ R2 is satisfied with respect to the lower limit value R1 and the upper limit value R2, the peripheral speed ratio R ′ of the developing sleeve 30 at the time of recording image formation is determined from R0 or R by R ′ = kR0. At the same time, the value of R0 is written in the memory 21 as the peripheral speed ratio R of the developing sleeve 30 for forming the next patch image.

Here, the patch image forming conditions of the initial value are set in advance so that the peripheral speed ratio R satisfies R1 ≦ R ≦ R2, and the toner adhesion amount, that is, the detection value D satisfies D1 ≧ D ≧ D2. I have. Therefore, the detection value D of the patch image formed using the peripheral speed ratio R of the developing sleeve 30 read from the memory 21 also satisfies D1 ≧ D ≧ D2. The reference adhesion amount M0 mg / cm ² is not limited to the average value in the stable region range, and a value in another stable region may be used. M is memory 7
The gradient peripheral speed ratio R0 may be obtained by an arithmetic program by reading M from the detected value D from the correspondence table of the detected value D and the toner adhesion amount M similar to the graph of FIG. Is obtained from a table that gives R0 corresponding to a set of R and D stored in the memory 7 in advance.
It is preferable to call R0 by simply and quickly. When the lower limit value R1 is smaller than R1, the change in the amount of toner attached to the change in the peripheral speed ratio of the developing sleeve 30 is too large, and the amount of toner attached tends to fluctuate.
The upper limit R2 is a limit value at which it becomes difficult to form a stable and clear toner image. When R0 exceeds R2, the value of k for calculating the developing sleeve peripheral speed ratio R 'in the image recording mode is determined. Even if it is increased, it is difficult to obtain an ideal toner adhesion amount of a recorded image, for example, 0.66 mg / cm ² , and this is a limit value that toner scattering easily occurs. k is a value of about 3, but may vary depending on the developer, temperature and humidity conditions, and the like. Developing sleeve peripheral speed ratio R 'in image recording mode
May be obtained in accordance with an arithmetic program, but it is preferable to easily and quickly obtain R 'by R0 and k from a relation table of R' to R0 and k stored in the memory 7 in advance. R ′ = kR may be used for R ′.

By forming a recorded image by using the peripheral speed ratio R 'of the developing sleeve 30 in the image recording mode obtained as described above, the color balance can be prevented without causing contamination inside the apparatus or excessive consumption of the developer. , And a predetermined number of clear color images excellent in image quality can be formed. Next, prior to forming a new recording image, a patch image is formed using the peripheral speed ratio R of the developing sleeve 30 read from the memory 21, and based on the detected value D, a patch image is similarly formed in the image recording mode. And a predetermined number of similarly vivid color images can be formed by using this. By this repetition, a clear color image can be stably formed. However, the developing performance becomes excessively large for some reason including a change in the developer and environmental conditions, and conversely, the developing performance is reduced. As described above, the relationship curve between the peripheral speed ratio R of the developing sleeve 30 and the toner adhesion amount M changes, and the detection value D of the patch image formed using the peripheral speed ratio R of the developing sleeve 30 read from the memory 21 is D1 ≧ Even if D ≧ D2 is satisfied, the gradient peripheral speed ratio R0 may not satisfy R1 ≦ R0 ≦ R2.

When R0 no longer satisfies R1 ≦ R0 ≦ R2, that R0 is set to the peripheral speed ratio R for the next patch image formation.
Without changing the patch image forming conditions as described below without performing the following processing without storing in the memory 21 nor calculating the peripheral speed ratio R ′ of the developing sleeve 30 in the image recording mode. As the patch image forming condition, P1 ≧ P + △ P from the condition that the uniform charging condition of the image carrier 1 by the charger 2 in the previous forming condition is set to the potential P.
(R0−R3) / | R0−R3 | ≧ P2 (where P1,
P2 and ΔP are constants such as 700 V, 800 V and 10 V, and R3 is a constant satisfying R1 ≦ R3 ≦ R2. P) of a potential satisfying the following equation: P + △ P (R0−R3) / |
0−R3 |, that is, P + 10V when R0> R2
Or, the same conditions as the above forming conditions are used except that the condition is changed to obtain P-10V when R0 <R1. This changed uniform charging condition is stored in the memory 21 for the next image formation.
Is written to.

The D formed by the above modified conditions
The gradient peripheral speed ratio R0 obtained by R0 = R × (M0 / M) from the peripheral speed ratio R obtained by developing the patch image of the detection value D satisfying 1 ≧ D ≧ D2 satisfied the condition of R1 ≦ R0 ≦ R2. when,
As described above, R0 is written in the memory 21 as the peripheral speed ratio R of the developing sleeve 30 for forming the next patch image, and the developing sleeve peripheral speed ratio R 'in the image recording mode is determined from R0 by R' = kR0. To form a clear color image.

The re-formed patch image also has a gradient peripheral speed ratio R0 obtained from the developed peripheral speed ratio R of R1 ≦ R0 ≦ R2.
Is not satisfied, formation of a patch image is repeated again. And R1 ≦ R0 ≦ R2
Is obtained, a recorded image is formed in the same manner as described above, but the patch image is formed within the variable charging condition of the charger 2 that gives the uniform charging potential P of the image carrier 1 that satisfies P1 ≧ P ≧ P2. When the gradient peripheral speed ratio R0 obtained from the peripheral speed ratio R of the developing sleeve 30 on which the image is formed does not satisfy R1 ≦ R0 ≦ R2, for example, the rotation of the image carrier 1 is stopped and a warning display is performed. The control flowchart of the control unit 8 shown in FIG. 6 shows the above example, which prevents formation and recording of a defective image and indicates an appropriate time to perform maintenance such as cleaning of the apparatus and replacement of parts. become.

As another example, as described above, the developing sleeve 30 on which a patch image is formed within the variable charging conditions of the charger 2 is described.
Is equal to R1 ≦ R0 ≦ R.
If 2 is not satisfied, a recorded image is formed under image forming conditions including the latest recorded image data stored in the memory 21, and a warning is displayed. The control flowchart shown in FIG. 7 of the control unit 8 shows this example. This also appropriately prevents formation and recording of a defective image, and indicates an appropriate time to perform maintenance such as cleaning of the apparatus and replacement of parts. It will be.

As another example, when the developing units 3Y to 3BK use a two-component developer, the developing sleeve 30 on which a patch image is formed within the variable charging conditions of the charger 2 as described above. The gradient peripheral speed ratio R0 obtained from the peripheral speed ratio R is R
When 1 ≦ R0 ≦ R2 is not satisfied, the toner density T of the developer in the latest patch image forming condition stored in the memory 21 is set to T1 ≧ T + ΔT (R0−R3) / | R0
−R3 | ≧ T2 (where T1, T2, and ΔT are, for example, 6w
These are constants such as t%, 12 wt%, and 1 wt%. T + ΔT (R0-R3) / | R0
−R3 |, that is, T + 1 wt% when R0> R2
Alternatively, a patch image is formed again under the same conditions as the latest patch image forming conditions except that the control is performed so as to control to T-1 wt% when R0 <R1.

If the gradient peripheral speed ratio R0 obtained from the above-described peripheral speed ratio R for forming a patch image does not satisfy R1 ≦ R0 ≦ R2, the writing of R0 into the memory 21 and the formation of a recorded image are not performed. Is repeated by changing the toner density of the developer and forming the patch image again, and the gradient peripheral speed ratio R0 obtained from the peripheral speed ratio R at which the patch image is formed is R1 ≦
When R0 ≦ R2 is satisfied, R0 is written in the memory 21 as the peripheral speed ratio R for the next patch image formation, and the peripheral speed ratio R ′ in the image recording mode is obtained from R0, and R ′ is stored in the memory 2.
1 to form a clear recorded image with excellent color balance by R '.

However, when the gradient peripheral speed ratio R0 obtained from the peripheral speed ratio R for patch image formation does not satisfy R1 ≦ R0 ≦ R2 within the variable toner density condition of the developer satisfying T1 ≧ T ≧ T2. Then, the rotation of the image carrier 1 is stopped and a warning is displayed. The control flowchart shown in FIG. 8 by the control unit 8 shows this example. According to this, the formation and recording of a defective image are prevented, and the time for performing maintenance such as cleaning of the apparatus and replacement of parts can be slightly extended.

As another example, as described above, T1 ≧ T
The gradient peripheral speed ratio R0 obtained from the peripheral speed ratio R of the patch image formation within the variable toner density condition of the developer satisfying ≧ T2 is R1.
If ≤R0≤R2 is not satisfied, a recorded image is formed under image forming conditions including the latest recorded image data stored in the memory 21 and a warning is displayed. The control flowchart shown in FIG. 9 of the control unit 8 shows this example. This also appropriately prevents the formation and recording of a defective image, and slightly extends the time for performing maintenance such as cleaning of the apparatus and replacement of parts. Can be.

The image forming apparatus of the present invention is not limited to a color image forming apparatus, but may be a monochrome image forming and recording apparatus. Further, as mentioned above, in the case of a color image forming apparatus, a plurality of toner images may be superimposed within one rotation of the image carrier.

[0033]

As described in detail above, according to the image forming apparatus of the present invention, it is impossible to control the rotation speed of the developing sleeve in accordance with the detection result, thereby making it impossible to properly change the toner adhesion amount. By controlling the rotation speed of the developing sleeve, it is possible to stably realize the required maximum amount of toner adhered, and to obtain a remarkable effect that a clear toner image can be formed.

[Brief description of the drawings]

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

FIG. 2 is a use state diagram illustrating an example of a toner image detection sensor.

FIG. 3 is a circuit diagram illustrating an example of a toner image detection sensor.

FIG. 4 is a side view of the image carrier showing a surface of the image carrier with respect to adjustment of a detection sensor and a detection result.

FIG. 5 is an output voltage graph relating to adjustment and detection of a detection sensor.

FIG. 6 is a flowchart illustrating an example of image forming condition control by a control unit in FIG. 1;

FIG. 7 is a flowchart illustrating another example of image forming condition control by the control unit in FIG. 1;

FIG. 8 is a flowchart illustrating another example of image forming condition control by the control unit in FIG. 1;

FIG. 9 is a flowchart illustrating another example of image forming condition control by the control unit in FIG. 1;

FIG. 10 is a graph showing a relationship between a patch image toner adhesion amount and a relative output of a detection sensor.

FIG. 11 is a graph showing the relationship between the peripheral speed ratio of a developer carrying carrier to an image carrier and the amount of patch image toner adhered.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Charger 3Y, 3M, 3C, 3BK Developing device 30 Developer carrier (developing sleeve) 6 Cleaning device 7, 21 Memory 8 Control unit 9 Detection sensor 91 Light emitting element 92 Light receiving element 10 Detection circuit 22 Image Exposure means

Claims (5)

[Claims] A charging means for uniformly charging the surface of the image carrier around the image carrier; an exposure means for irradiating the charged surface with an image to form an electrostatic image; A reference image formed in advance on a surface of a rotating image carrier, including a developing unit having a developer transporting carrier for developing the toner image on the image carrier, and a detection sensor for detecting the adhesion amount or density of the toner image on the image carrier. The detection sensor detects a patch image, which is a toner image of the toner image, to obtain a detection value corresponding to the toner adhesion amount of the patch image, and determines the detection value and the circumference of the developer transporting carrier that has developed the patch image with respect to the image carrier. An image forming apparatus for determining the peripheral speed ratio of a developer carrying carrier for forming a toner image during recording image formation based on a speed ratio, wherein the peripheral speed ratio is a value obtained by developing the detected value and the patch image. Ratio of required peripheral speed ratio change and toner adhesion amount change If the calculated value corresponding to the value is out of the predetermined range, the charging surface by the charging means is determined without determining the peripheral speed ratio of the developer transporting carrier in the image recording mode based on the detected value and the peripheral speed ratio. In the case where the electric potential of the developer or the developer used for the developer carrying carrier is two-component, one or both of the toner concentrations of the developer are adjusted, and thereby the patch image is newly formed on the image carrier surface. And the detection value is detected by the detection sensor to obtain a detection value corresponding to the toner adhesion amount of the patch image, and the calculated value obtained from the detection value and the peripheral speed ratio obtained by developing the patch image is within the predetermined range. An image forming apparatus for determining the peripheral speed ratio of the developer transporting carrier in the image recording mode based on the detected value and a peripheral speed ratio obtained by developing the patch image. 2. The image forming apparatus according to claim 1, wherein the detection sensor is configured to irradiate the light of the light emitting element to the surface of the image carrier and receive the reflected light by the light receiving element. 3. When the calculated value is out of a predetermined range,
When the potential of the charged surface by the charging unit is changed within a predetermined range, and the calculated value does not fall within the predetermined range in the change within the predetermined range, the recorded image of the recording image is formed based on predetermined toner image forming conditions. The image forming apparatus according to claim 1, wherein a toner image is formed or a warning is displayed, and the rotation of the image carrier is stopped. 4. When the calculated value is out of a predetermined range,
The potential of the charging surface by the charging means is changed within a predetermined range, and when the calculated value is not within the predetermined range, the developer used for the developer carrying carrier is changed within the predetermined range. In the case of two components, the toner concentration of the developer is changed step by step within a predetermined range, and when the calculated value does not fall within the predetermined range with the change within the predetermined range,
3. The image forming apparatus according to claim 1, wherein the toner image formation of the image recording is performed or a warning is displayed based on predetermined toner image forming conditions, and the rotation of the image carrier is stopped.
An image forming apparatus according to claim 1. 5. A toner image forming apparatus using the peripheral speed ratio in an image recording mode in which the predetermined toner image forming condition is determined based on the latest detected value and the peripheral speed ratio obtained by developing a patch image. The image forming apparatus according to claim 3, wherein the condition is a condition.