JP3464850B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copier, a facsimile
And an image forming apparatus such as a printer. [0002] 2. Description of the Related Art Conventionally, as an image forming apparatus of this type, an image forming apparatus
An image is formed on a photoreceptor belt or intermediate transfer belt as a carrier.
Create a pattern for image density detection,
Using a sensor to detect the detected density and the reference density.
And developing bias voltage, charging bias voltage,
By changing process conditions such as transfer bias voltage,
It is known to perform a troll. However, in this case, an image density detecting
Pattern on photoreceptor belt or intermediate transfer belt
The effect of the final transfer efficiency on the paper
It is not reflected and the detected density is compared with the actual image density on paper.
If so, the density will be high. Also, photoreceptor, intermediate transfer
The body must be mixed with carbon, etc. to make it conductive.
Because it is difficult to use white color from the above, toner density detection
There was a problem that the method became complicated. Therefore, the first visible image on the image carrier is used.
A transfer roller for transferring to paper, and a second transfer roller on the image carrier.
Means for transferring a visible image to the transfer roller, and the transfer
Means for cleaning the roller, and
Density detecting means for detecting a second image density;
Density control means for controlling the toner density from the detection density of the sensing means
A step, wherein the density control means has a reference density value,
The density detected by the density detecting means is the reference density.
If it is different from the reference density value, the toner density is controlled.
An electrophotographic apparatus having a means for automatically adjusting
(See, for example, JP-A-3-2560679).
See). In this device, a visible image for image density detection
The visible image on the image carrier to paper
The actual transfer to the transfer roller to be transferred
Detecting the second image density on the camera,
Measurement can be performed more accurately than
Accuracy can be improved. The transfer roller is white
Can easily detect the image density.
Therefore, the accuracy of density detection can be improved. [0005] However, the transfer ro
Is an insulator and is not affected by humidity in the air
However, the resistance of actual paper varies extremely due to humidity in the air.
Transfer rate to the transfer roller and transfer to the actual paper
There is a shift due to this humidity between the shooting rate and proper control.
However, there was a problem that some people could not do it. What
In the specific device disclosed in the above publication,
Transfer roller cleaning means
Since a cleaning member is used,
The size and cost of the equipment are increased due to the additional arrangement of cleaning members.
Up and transfer with mechanical cleaning
There was also a problem that the life of the roller was shortened. [0006] The present invention has been made in view of the above problems.
The objectives are environmental and temporal changes.
Optimal control of process conditions even when movement occurs
To provide an image forming apparatus capable of obtaining
You. [0007] [0008][MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
Claim 1 The image forming apparatus of the related art includes an image bearing member and the image bearing member.
Visualized image forming means for forming a visualized image comprising a developer on a carrier
And a visible image formed on the image carrier through an intermediate transfer member.
Directly or directly to the transfer material using a transfer electric field
An image forming apparatus having a transfer unit.
A visible image for detection is formed on the body, and the transfer means
The detected visual image is transferred to a predetermined detecting transfer portion.
To form a transfer image for detection on the transfer section for detection.
Control unit for forming a transferred image and detecting the transferred image for detection
Transfer image detecting means, based on an output of the transferred image detecting means
Process to control process conditions that affect image density
Condition control means, and transfers the detection transfer section to the transfer
Formed with a material that has electrical resistance and moisture absorption properties similar to the copying material
It is characterized by having done. [0009] Here, the process in each of the claims is performed.
The charging conditions are as follows:
Output voltage, exposure conditions of the exposure device,
Conditions, such as the size of the screen, the transfer electric field strength of the transfer device, etc.
I can do it. The transfer unit for detection constitutes the transfer unit.
Even if you use the peripheral surface of a special member additionally provided to
The transfer material may be placed on the image carrier or the intermediate transfer
When transferring the visual image on the object, a transfer material is applied to the visual image.
Illustration provided to back up the transfer material to make contact
For example, the peripheral surface of the transfer roller may be used. In the latter case,
Using a peripheral surface outside the image area on the transfer roller
desirable. Further, the visible image forming means includes a latent image forming means and
It can be configured using developing means. Further, the latent image forming hand
A latent image corresponding to the image signal of each color is formed for each color at the stage,
The latent images of the respective colors have different colors of developer.
The above-described developing device configured to include a plurality of developing units.
Obtain a color image by visualizing with the corresponding developing unit
Can also be configured to. [0010] [Action] ClaimsOneIn an image forming apparatus, detection and transfer
The image forming control means controls the microscope for detection on the image carrier.
An image is formed, and a predetermined detection is performed by the transfer unit.
The detection image is transferred to the transfer portion of the detection transfer portion.
A transfer image for detection is formed thereon. This transfer image for detection is
Detected by transfer image detection means, and by process condition control means
Process conditions that determine image density based on this detection output
Control the matter. [0011] [0012]And onThe transfer section for detection
Formed of a material having electrical resistance and moisture absorption properties similar to
The transfer section for detection has a temperature similar to that of the transfer material.
Or be affected by humidity. This allows
In the same way as when transferring to a transfer material, the effect of temperature or humidity
The received transfer image for detection can be obtained. [0013] 【Example】 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
You. FIG. 1 illustrates a color image forming apparatus (color image forming apparatus) according to an embodiment.
FIG. 2 is a schematic configuration diagram of a laser printer. In FIG.
Reference numeral 1 denotes a flexible belt-shaped photoconductor serving as a belt-shaped image carrier,
The belt-shaped photoreceptor 1 is provided between rotating rollers 2 and 3.
And is rotated clockwise by the drive of the rotation roller.
4 is a charging member as a charging means, 5 is a laser as an image exposure means
The writing units 6 each store a specific color developer.
Rotary developing device having a plurality of developing means or developing units
An imaging device. The laser writing unit 5 has an upper surface
Into a holding housing with a slit-shaped exposure opening
It is built into the device body. The laser writing system
In the knit 5, in addition to the optical system shown, the light-emitting portion
An optical system or the like having an integral optical transmission body can also be used. The belt
Charging position by the electrical member 4 and the laser writing system unit
In the optical writing position by means of the
One of two or more rollers
ing. The developing units are, for example, yellow, magenta, and cyan.
Ann, each containing black developer, specified
At or in contact with the belt-shaped photoconductor 1
Each developing sleeve is provided so that the latent image on the photoreceptor belt 1 is not contacted.
Has the function of visualizing by tactile or contact development
I have. Reference numeral 10 denotes an intermediate transfer belt as a transfer image carrier,
The intermediate transfer belt 10 includes a driving roller 11 and a driven roller 1.
2 and is rotated by the driving of the rotating roller.
It is rotated clockwise. Intermediate transfer with the belt-shaped photoreceptor 1
The belts 10 are in contact with each other at the three rotating rollers.
The first visible image on the belt-shaped photoconductor 1 is an intermediate transfer
Intermediate rotation by the bias roller 13 provided in the belt
The image is transferred onto the photo belt 10. And a similar professional
By repeating the process, the second visualization and the third
And the fourth visualized image are intermediate transfer images, respectively.
So that it will not overlap with the
It is designed to be transcribed. Contact with intermediate transfer belt 10
A paper transfer roller 14 is provided so as to be separated. this
The paper transfer roller 14 has a power supply 42 as shown in FIG.
Therefore, a predetermined transfer bias is applied.
You. Reference numeral 15 denotes a belt-like feeling provided on the rotating roller 2.
A cleaning device for the optical element 1;
Of the cleaning device 16
16A is a surface of the intermediate transfer belt 10 during image formation.
During cleaning after image transfer, kept at a more distant position
Only the surface is pressed against the surface of the intermediate transfer belt 10 as shown in the figure.
You. The intermediate transfer belt 10 and the belt-shaped photoreceptor
1 is a seamless belt. (Hereinafter, margin) A color image by the color image forming apparatus
The formation process is performed as follows. First, in this embodiment
Multicolor image formation is performed according to the following imaging system
Is done. That is, a color image forming apparatus not shown
Color image data consisting of a separate image reading device
In the input section, the image sensor scans the original image
Data is obtained, and this data is processed by the image data processing unit.
Thus, image data is created. This image data
It is stored in the image memory. Image data in the image memory
The data is taken out at the time of recording and
-Input to the image forming apparatus. That is, the color image
Color output from an image reading device separate from the forming device
A signal is input to the laser writing unit 5.
Then, in the laser writing unit 5, the semiconductor
A laser beam generated by a laser (not shown) is driven
Rotated by polygon mirror 5B rotated by motor 5A
Is scanned, and the optical path is bent by a mirror via the fθ lens 5C.
And the charge is removed by the charge removing lamp 21 in advance.
Of the belt-shaped photoconductor 1 uniformly charged by the electric member 4
The peripheral surface is exposed to form an electrostatic latent image. Where dew
The image pattern that glows yellow the desired full-color image
Color, magenta, cyan, and black
It is an image pattern. Each formed electrostatic latent image is a rotating type
Development of yellow, magenta, cyan, and black by developing device
And a monochromatic image is formed. Belt photosensitive
The monochromatic image formed on the body 1 is transferred to the belt-shaped photoconductor 1.
Intermediate transfer belt 10 that rotates counterclockwise while contacting
Transcribed above. Yellow formed on photoreceptor belt 1
-, Magenta, cyan, and black monochrome images for intermediate transfer belt
It is superimposed sequentially on the ten surfaces. On the intermediate transfer belt 10
Yellow, magenta, cyan and black images superimposed on
The image is fed from a paper feed table 17 to a paper feed roller 18 or a registration roller.
Paper transfer roller 1 on the transfer paper conveyed to the transfer unit through
4 is transferred. After the transfer, the transfer paper is transferred to the fixing device 2
0 to complete the full-color image. FIG. 2 is a partially enlarged view of the color image forming apparatus.
It is. The end of the intermediate transfer belt 10 has six markers.
And the mark detection sensor 40
By detecting an arbitrary mark (for example, 41A),
Start recording, go around once and detect the same mark 41A again
Then, the writing of the second color is started. At this time,
Marks 41B to 41F are used as write timing
Control the number of marks to prevent
A mask is to be applied. In this embodiment, the laser writing
Unit 5 detects the latent image for detection separately from the latent image for the image.
An image pattern is formed and developed by the rotary developing device 6
Then, the developed image is transferred to the intermediate transfer belt 10, and
Is transferred onto the paper transfer roller 14, and
To form a toner image for detection. And this toner image
Is a paper roll used as a transfer unit for detection as shown in FIG.
Optical sensor 2 for detecting the amount of toner on the surface of copying roller 14
Detect at 2. Based on this detection result, the paper transfer roller
14 to an optimum transfer bias.
Control so that FIG. 3 shows a transfer image inspection including the optical sensor 22.
It is a figure which shows the schematic structure of the circuit part which comprises an output means. L
Optical sensor 2 composed of ED and phototransistor Tr1
2. Generate a voltage with the current that changes depending on the amount of received light
Resistor R, and converts the voltage of the resistor R into digital data.
A / D converter, transistor Tr2,
It consists of a DA converter that controls the transistor. Said A
There is a low-pass filter at the preceding stage of the D converter. FIG. 4 shows the relationship between the humidity and the optimum paper transfer bias.
It is a graph which shows a relationship. As can be seen from this figure, the humidity
The higher the paper transfer bias, the lower the optimal paper transfer bias
You. Therefore, the environment changes under the constant paper transfer bias condition.
The optimum bias condition is exceeded, the density decreases,
Shift occurs. Therefore, in this embodiment, the detection trigger is used.
Transfer the toner image from the intermediate transfer belt 10 to the paper transfer roller 14.
Copy and form a toner image for detection on the paper transfer roller 14
The paper transfer roller 14 and the intermediate transfer belt 10
Separate by a predetermined amount to prevent environmental fluctuations such as humidity.
The toner image for detection is transferred to the paper transfer roller 1 in an affected form.
4 can be formed. FIG. 5 shows a paper transfer roller contacting / separating machine for this purpose.
It is a schematic structure figure of a structure. The paper transfer roller 14 is at the fulcrum A
It is supported by the arm 50 in the center, and it is
Being pulled. The other side of this arm 50 is an eccentric cam
52. At least three eccentric cams
Has a radius d1, d2, and d3 portions, and the portion having the radius d1 is
With a delicate spacing, the part with radius d2 is the paper transfer roller
14 and the intermediate transfer belt 11 are completely contacted and pressurized.
State, the part with the radius d3 is the paper transfer roller 14 and the intermediate transfer
Formed to be completely separated from belt 11
Have been. When not printing, print the part with radius d3
Use the part of radius d2 at the time, and use the part of radius d1 at the time of detection.
You. By using this radius d1 part, the toner image for detection is
When transferring from the transfer belt 10 to the paper transfer roller 14,
By providing a delicate gap between the two surfaces,
Even if the copying roller 11 is used, the paper
The same characteristics as those obtained by the transfer are obtained. FIG. 6 shows the detection of the detection circuit shown in FIG.
Show characteristics. This detection circuit is used to detect
The higher the density of the toner image on the
There is a characteristic that output power is reduced. In the low concentration range, the concentration
The detection output changes following the change.
From the concentration, the change rate of the detection output decreases, and
They tend to unify or reverse.
Therefore, in practice, the effective S / N area effective for practical use is low.
It can be seen that this is a density region. Therefore, in this embodiment,
In order to use this area with good S / N, the detection
You are setting a turn. FIG. 7 shows a detection pattern used in this embodiment.
FIG. The pattern 53 in FIG.
Consists of a set of dots for full power writing with
The background of the photoconductor is exposed between the dots. This putter
Unit 53 due to the change in transfer characteristics
Hiding the photoreceptor while changing the amount of toner per product
And the above detection characteristics performance is improved.
Use the low-concentration area where the detection output changes
Can be used. The transfer rate of 53a in FIG.
A pattern for detection on the paper transfer roller 14 when it is lowered
53b shows the case where the transfer rate is increased
The state of the detection pattern on the paper transfer roller 14 is shown.
You. FIG. 8 shows the spectral reflection characteristics of each toner color.
It is. Available colors are cyan, magenta, yellow
-Uses black. Each of the wavelengths
The different reflection characteristics. The long wavelength side is cyan,
Zenda and yellow have the same characteristics, but black has characteristics
Are different. On the other hand, the short wavelength side varies slightly for each color.
It is clear that they have common absorption characteristics
Call Similar characteristics are obtained irrespective of the toner color. So
Here, in this embodiment, as described above, the single optical sensor 2
When using 2 for each color, use the above short wavelength side
Like that. Specifically, the region of blue light to ultraviolet light
Or more specifically, a wavelength range of 400 nm or less.
You. FIG. 9 shows the detection pattern (1, 2, X) and the intermediate pattern.
The arrangement on the peripheral surface of the transfer belt 10 is shown. Paper transfer roller 1
One detection pattern is created for the circumference and the detection pattern
Between the areas of the same circumference in which the
And the detection pattern is the same as that of the
The region is formed not partially but entirely.
Then, such a plurality of detection patterns were created.
The surface portion of the intermediate transfer belt 10 faces the paper transfer roller 14.
Change the paper transfer bias for each detection pattern
Let me. Thus, the intermediate transfer belt 10
Instead of creating an interval between multiple detection patterns,
A continuous pattern is formed on the intermediary transfer belt 10 and
Each bias to be applied to the transfer roller 14
Predetermined transfer bars different from each other for the time corresponding to the pattern
Switch to EAS and transfer the detection pattern to the paper transfer roller
During the period in which no paper is created, the intermediate transfer belt 10
May be biased so that toner does not transfer to the roller 14.
No. Then, for example, a detection pattern denoted by reference numeral 1 in FIG.
Use the first bias 1 to transfer
During one rotation of the transfer roller 14, the paper transfer roller has a reverse via.
The toner adhering to the roller with the intermediate transfer belt.
Reverse transition to 10. Next, the next detection is performed with the second bias 2.
The pattern 2 is transferred to the roller in the same manner as described above, and the next 1
During the rotation, a reverse bias is applied to the
The toner is reversely transferred to the intermediate transfer belt 10. Similarly,
Sensor detection for bias conditions repeated until bias X
Find the value. Here, each of the intermediate transfer belts 10
All patterns should be the same conditions
You. FIG. 10 shows a detection pattern as shown in FIG.
Timing when forming and detecting on intermediate transfer belt 10
3 shows an operating chart. The horizontal axis is time and the vertical axis is writing
Indicates the distance from the sensor detection position on the paper transfer roller to
The light 5a from the laser writing unit 5 in FIG.
From the exposure position P1 on the photosensitive member 1 to the intermediate transfer belt 10
Transfer position P2 to paper transfer roller 14 and transfer position P to paper transfer roller 14
3 to the position P4 detected by the optical sensor 22.
Distance. The write timing at time t1 is a constant line
Sensor on paper transfer roller 14 when moving at high speed
The time to reach the position P4 is t1 ｀. This time t1
The time after the time required for one rotation of the paper transfer roller 14 from ｀
Until t2 バ イ ア ス, transfer is performed with the first bias 1, and at time t2 ｀
After the time required for one rotation of the paper transfer roller 14
Apply a reverse bias and rotate the toner intermediately until the time t3
Reverse transfer onto the photo belt 10. Up to bias X
repeat. FIG. 11 shows a plurality of detection signals as described above.
The paper transfer roller 1 is used to transfer the pattern with different transfer biases.
4 and the density is detected by the optical sensor 22.
9 is a graph showing the results. The horizontal axis is the paper transfer bias,
The vertical axis represents the detection output of the sensor. In this example, the detection result is
As shown in the figure, it has a downward convex characteristic. Such detection results
Is approximated in the device by, for example, a second-order least squares method, and
Transfer bias corresponding to the minimum value of
-Transfer bar corresponding to the detection pattern with a large amount of adhesion
Based on the bias, derive the optimum bias value and transfer it to the transfer buffer.
The control value of EAS. In the above embodiment, the detection toner
The image is transferred from the intermediate transfer belt 10 to the paper transfer roller 14.
To form a toner image for detection on the paper transfer roller 14
At this time, the paper transfer roller 14 and the intermediate transfer belt 10 are
Separated by an amount, the effect of environmental fluctuations such as humidity
The toner image for detection on the paper transfer roller 14
However, instead of this, the detection pattern
Depending on the structure of the surface portion of the paper transfer roller
In the form affected by environmental fluctuations such as humidity and humidity.
So that a toner image can be formed on the paper transfer roller 14
Is also good. FIG. 12 shows a paper transfer roller 14 according to the example.
FIG. 3 is a perspective view of a mechanism portion of an intermediate transfer belt 10 used. This
The paper transfer roller 14 in the example of FIG.
Outside), characteristics similar to recording paper (moisture absorption characteristics of atmospheric humidity)
14A) is attached. This member 14A
For example, non-cotton pulp whose surface is coated with resin
Materials can be used. This portion 14A is used for transfer paper
Similarly to the transfer paper,
The detection pattern is transferred while being in contact with the transfer belt 10.
Let me copy. Then, the toner adhesion amount on this portion 14A is
Similarly, the optimal transfer bias is detected by the optical sensor 22.
To control. In the above embodiment, the intermediate transfer belt 1
From 0 to a transfer unit for detection provided on the paper transfer roller 14.
The pattern for detecting the shooting conditions in the form affected by humidity etc.
Was set to transfer the humidity, but instead
Or a temperature sensor is provided, and based on the output of the sensor.
For example, based on the relationship shown in FIG.
The transfer bias is controlled, and the intermediate transfer is performed by using the controlled transfer bias.
The detection pattern formed on the transfer belt 10 is
Actually transferred to the default 14 and based on this detection result
Therefore, the transfer bias control value may be finely adjusted.
No. Further, the transfer bias was controlled as a process condition.
May alternatively or additionally include other process conditions.
May control. [0028] Claims of the InventionOneAccording to the image forming apparatus, the detection
The transfer image forming control means controls the detection of the image formed on the image carrier.
The output visual image is transferred to a predetermined detection transfer portion by the transfer means.
The transfer image for detection formed by the
Process conditions are controlled by the process condition control means based on the detected output.
The image density to the left according to the aging fluctuation.
The right process conditions can be changed appropriately.
In addition, the transfer of the detection visual image to the detection transfer portion
Temperature or humidity in the same manner as the transfer to the transfer material.
Temperature or humidity.
It is possible to perform appropriate process control according to environmental changes.
You. Therefore, a desired image can be stably obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a color image forming apparatus according to an embodiment. FIG. 2 is a partially enlarged view of the color image forming apparatus. FIG. 3 is a schematic configuration diagram of a circuit unit constituting a transfer image detection unit used in the color image forming apparatus. FIG. 4 is a graph showing a relationship between humidity and an optimum paper transfer bias. FIG. 5 is a schematic configuration diagram of a paper transfer roller contact / separation mechanism. 6 is a characteristic diagram showing detection characteristics of the detection circuit shown in FIG. FIG. 7 is an explanatory diagram illustrating an example of a detection pattern used in the present embodiment. FIG. 8 is a characteristic diagram showing a spectral reflection characteristic of each toner color. FIG. 9 is an explanatory diagram of a detection pattern and an arrangement on a peripheral surface of an intermediate transfer belt. FIG. 10 is a timing chart when the detection pattern of FIG. 9 is formed on an intermediate transfer belt and detected. FIG. 11 is a graph showing the result of transferring a plurality of detection patterns onto a paper transfer roller with different transfer biases and detecting the densities of the transfer patterns with an optical sensor. FIG. 12 is a perspective view of an intermediate transfer belt mechanism using a paper transfer roller according to a modification. [Description of Signs] 1 Photoconductor 6 Developing device 10 Intermediate transfer belt 14 Paper transfer roller 22 Optical sensor 42 Power supply device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Irie 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kenshi Shinohara 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-7-20669 (JP, A) JP-A-6-178112 (JP, A) JP-A-3-130786 (JP, A) JP-A-6-130831 ( JP, A) JP-A-7-152267 (JP, A) JP-A-6-102777 (JP, A) JP-A-3-256067 (JP, A) JP-A-6-317949 (JP, A) JP JP-A-7-140757 (JP, A) JP-A-5-150578 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 303 G03G 21/00 370-540 G03G 15 / 16-15/16 103

Claims (1)

(57) Claims: 1. An image carrier, a visual image forming means for forming a visual image made of a developer on the image carrier, and a visual image formed on the image carrier. A transfer means for transferring, via an intermediate transfer member or directly, to a transfer material using a transfer electric field, wherein a visible image for detection is formed on the image carrier, and Means for transferring the visual detection image to a predetermined transfer portion for detection by means to form a transfer image for detection on the transfer portion for detection, and control means for forming a transfer image for detection, Transfer image detecting means for detecting, and a process condition control means for controlling a process condition which influences image density based on an output of the transferred image detecting means, wherein the transfer unit for detection is similar to the transfer material. Electrical resistance and
An image forming apparatus formed of a material having a moisture absorbing property .