JP2003287934A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that appropriately controls image density or color by detecting an image formed on a recording medium. <P>SOLUTION: The image forming apparatus 100 has: an image forming means A that forms a toner image on an image carrier 12; a transfer means 13 that transfers the toner image, formed by the image forming means A, to a transfer material 22 in a transfer position T2; a fixing means 14 that fixes the toner image, transferred by the transfer means 13, to the surface of the transfer material 22; a transport-direction switching means 16 that switches a direction of the transport of the transfer material 22 in order to invert the transfer material 22, with the toner image fixed on it by the fixing means 14, and transport it to the transfer position T2; a detecting means 50 that detects, in a specific detecting position, the toner image fixed on the transfer material 22 by the fixing means 14; and a control means 103 that controls the image forming means A based upon the result of the detection by the detecting means 50. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for printing an image on a recording medium.
The present invention relates to an image forming apparatus such as a printer and a copying machine to be formed.
Things. 2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has been used.
As an electrophotographic photoconductor (photoconductor) as an image carrier
It is formed by exposing a laser or the like that emits light according to an image signal.
The electrostatic latent image is used as a developer image (toner image) by the developer.
After the toner image is transferred to the transfer material,
2. Description of the Related Art There is known a device for wearing an image to obtain an image. In addition, an electrophotographic system for forming a color image
As an image forming apparatus, a multi-color image formed on a photoreceptor is used.
Transfer the toner image to a recording medium (transfer material) sequentially, or
Is the intermediate transfer of multi-color toner images formed on the photoconductor
After primary transfer to body, secondary transfer to transfer material and onto transfer material
An apparatus for forming a color toner image is known. Then, an electrophotographic image forming apparatus is used.
Changes in the environment where the device is placed or
There are fluctuations in each part of the device due to the use of the image forming device
And the density of the toner image formed on the transfer material by the image forming apparatus.
The degree fluctuates. In particular, electronic devices that form color images
In a photographic image forming apparatus, the density of a toner image
Even if the color fluctuates slightly, the color balance is lost.
There is a possibility that the image will always be constant regardless of the fluctuation of each part of the device.
It is desirable to maintain the density and gradation characteristics. Accordingly, an image forming apparatus for forming a color image is provided.
Changes in the environment in which the device is placed (e.g., absolute
Humidity) and the amount of laser exposure and development
Switch process conditions such as bias or laser
The image from which an electrostatic latent image is formed on the photoreceptor by exposure
Lookup table (LUT) for correcting signals
By adjusting the correction coefficient of
(For example, see Patent Document 1)
Teru. ) Can be considered. [0006] In addition, the fluctuation of each part of the image forming apparatus may occur.
To obtain constant image density and gradation characteristics.
Reference toner for density detection on photoreceptor or intermediate transfer member
A pattern of an image (hereinafter, referred to as a “toner density patch”)
The density of the toner density patch is formed by an optical sensor.
(For example, see Patent Document 2)
It is. In this method, the laser is detected based on the detection result of the optical sensor.
Switching process conditions such as the exposure amount and developing bias
Or forms an electrostatic latent image on the photoreceptor by laser exposure
Look-up table for correcting the image signal
Cable (LUT) to correct the image signal
Maintain constant image density and gradation characteristics (color balance)
It becomes possible. [Patent Document 1] Japanese Patent Application Laid-Open No. 09-80855 [Patent Document 2] Japanese Patent Application Laid-Open No. 11-65237 [0008]
Toner image density control using an optical sensor
A patch is formed on the photoreceptor or intermediate transfer member to detect the density.
Transfer the toner image to the transfer material and fix it.
The change in color balance of the image due to
That is not right. On the other hand, the toner image on the transfer material
Transfer efficiency in image transfer, heating and pressing by fixing
May change the color balance of the image.
Have been. The present invention has been made to solve the above problems.
Detects the image formed on the transfer material (recording medium)
Image to appropriately control the density or chromaticity of the image
It is an object to provide a forming device. [0010] The above objects are attained by the present invention.
This is achieved by an image forming apparatus. In summary, the present invention provides:
The feature is as follows. (1) Forming a toner image on an image carrier
Image forming means, and a toner image formed by the image forming means
A transfer means for transferring an image to a transfer material at a transfer position;
The toner image transferred by the copying means is fixed on the transfer material.
Fixing means for fixing the toner image by the fixing means.
Reversing means for reversing the transferred transfer material;
Transporting the inverted transfer material to the transfer position
The image is fixed on the transfer material by the two-sided conveying means and the fixing means.
The density or chromaticity of the detected toner image is detected at a predetermined detection position.
Detecting means for detecting, wherein the predetermined detection position is
After the transfer material has passed through the double-sided conveying means, the transfer position
Detecting means at a predetermined position on the transport path up to
Controlling the image forming means based on the detection result of the detecting means.
Controlling means for controlling the image forming apparatus
Place. (2) Forming a toner image on an image carrier
Image forming means, and a toner image formed by the image forming means
A transfer means for transferring an image to a transfer material at a transfer position;
The toner image transferred by the copying means is fixed on the transfer material.
Fixing means for fixing the toner image by the fixing means.
Reversing means having a reversing mechanism for reversing the transferred transfer material
And a toner image fixed on the transfer material by the fixing unit.
A detection method that detects the density or chromaticity of an image at a predetermined detection position
Step, wherein the predetermined detection position is within the reversing mechanism.
And a detection result of the detection means.
Control means for controlling the image forming means based on the
An image forming apparatus, comprising: (3) Further, the transfer material is transferred to the image forming apparatus.
Discharging means for discharging from the first surface, wherein the discharging means is provided on the first surface.
The transfer material on which the toner image is formed is detected by the detection unit.
After the transfer, the transfer material is discharged from the image forming apparatus.
The image forming apparatus according to the above (1) or (2),
Place. (4) The discharging means is provided for the transfer material.
After the first surface has been detected by the detection means, and
The second surface of the transfer material having a toner image formed on two surfaces
Is detected by the detection means, the transfer material is
(3) discharging from the image forming apparatus;
Image forming device. (5) The image forming means is provided for transferring the transfer material.
A plurality of reference marks having different gradations are provided on the first surface and the second surface.
Forming a toner image, wherein the control means detects the
Based on the detection results of the plurality of reference toner images
Controlling the image forming means.
(4) The image forming apparatus. (6) The image forming means is provided on an image carrier.
An image forming unit for forming a toner image;
Image signal to be corrected by calculation using a predetermined correction coefficient
And an image processing unit for transmitting to the image forming unit.
The control means is configured to perform the control based on a detection result of the detection means.
Adjust the coefficient relating to the correction operation in the image processing unit
The method according to any one of (1) to (5) above,
Image forming apparatus. (7) The image bearing member is an intermediate transfer member,
The image forming means includes: a photoconductor; and an electrostatic latent on the photoconductor.
Plural image formation consisting of developing means for developing an image with a developer
And a multi-color toner image in order on the intermediate transfer body.
Next, color toner images can be formed by superimposing
Any of (1) to (6) above,
Image forming apparatus. (8) The image bearing member is a photosensitive member.
Image forming means for developing the electrostatic latent image on the photoreceptor with a developer;
A plurality of image forming units having a developing unit for forming an image;
The transfer unit is configured such that the image forming unit develops the image on the photoconductor.
By transferring the toner image to the transfer material sequentially, the toner image is transferred onto the transfer material.
(1) wherein a toner image is formed.
The image forming apparatus according to any one of (1) to (6). (9) Forming an image composed of a plurality of colors on a recording medium
Image forming means for forming an image, and an image formed by the image forming means.
Conveying the recording medium to reverse the formed recording medium
A second direction different in direction from the first direction to the first direction
Direction switching means for switching the image forming direction, and the image forming
The chromaticity of the image formed on the recording medium by the
Detection means for detecting at a detection position, wherein the predetermined detection
The known position is determined by the transport direction switching means.
After the body conveyance direction is switched to the second conveyance direction
The conveyance path on which the recording medium is conveyed, and
A detecting means which is a predetermined position leading to the image forming means;
The chromaticity of the image composed of the plurality of colors detected by the
The image to adjust the density of each of the plurality of colors based on the
Control means for controlling the image forming means.
Image forming apparatus. (10) The recording medium is transferred from the image forming apparatus.
Discharging means, which discharges the image on the first surface.
After the recording medium on which the image is formed is detected by the detection unit
Ejecting the recording medium from the image forming apparatus
(9) The image forming apparatus according to the above (9). (11) The discharging means is provided for the recording medium.
After the first surface has been detected by the detection means,
The second surface of the recording medium having an image formed on the second surface
Is detected by the detection means, the transfer material is
(10) wherein the sheet is discharged from the image forming apparatus.
Image forming apparatus. (12) The image forming means includes:
The first surface and the second surface have a plurality of groups each having a different gradation.
Forming a quasi-image, wherein the control means detects the
The image based on the detection result of the plurality of reference images.
Controlling the forming means.
Image forming device. (13) The image forming means is provided on a recording medium.
An image forming unit for forming an image and an image to be formed;
The image signal is corrected by a calculation using a predetermined correction coefficient.
An image processing unit for transmitting to the image forming unit;
Means, based on a detection result of the detection means,
Before adjusting the density of each color in the image processing unit,
Adjusting the coefficient relating to the correction operation.
(9) The image forming apparatus. Hereinafter, an image forming apparatus according to the present invention will be described.
Will be described in more detail with reference to the drawings. FIG. 1 shows a first embodiment of a full-color image.
1 is an example of an image forming apparatus capable of forming an intermediate transfer body 1
Of a tandem-type image forming apparatus 100 employing the image forming apparatus 2
FIG. 3 is a diagram illustrating a configuration. With reference to FIG.
An outline of the operation of the used image forming apparatus will be described. The image forming apparatus 100 shown in FIG.
Personal computer communicably connected to the body
External host device such as a printer or image forming device
Image signal from a document reading unit (not shown)
You. Then, based on the image signal, the image forming apparatus 100
Drum-type electrophotographic photosensitive member (photosensitive
An electrostatic latent image is formed on the drum 23 and the current
A plurality of monochromatic toners are supplied by supplying the toner of the image unit 25.
An image is formed, and the monochrome toner image is sequentially transferred to the intermediate transfer body 1
2 to form a color toner image.
The color toner image is transferred to the transfer material 22. Image formation
The apparatus 100 includes a color toner transferred onto the transfer material 22.
After the image is fixed on the transfer material 22 by the fixing unit 14
Then, the transfer material 22 is discharged out of the apparatus. The image forming means A is developed and superposed.
Number of toner colors (yellow (Y), magenta (M), shear
(C), black (K) (4 colors)
Station P (Py, Pm, Pc, P
k) a photosensitive drum as an image carrier (first image carrier)
23 (23Y, 23M, 23C, 23K) and primary band
And the current means 24 (24Y, 24M, 24C, 24K)
The image means 25 (25Y, 25M, 25C, 25K) and one
Next transfer unit 26 (26Y, 26M, 26C, 26K)
And a scanner unit 27 (27Y, 27
M, 27C, 27K) and a developer supply container (toner car)
(Tridge) 28 (28Y, 28M, 28C, 28K)
And each station Py, Pm, Pc, Pk
Intermediate transfer as a moving image carrier (second image carrier)
It has a body 12. The image forming apparatus 100 further includes a sheet feeding unit 1
1, secondary transfer means 13, fixing means 14, cleaning hand
A step 32 and the like are provided. More specifically, the photosensitive drums 23Y, 23
M, 23C, 23K are organic light on the outer circumference of aluminum cylinder
The drive motor M is formed by applying a conductive layer.
The driving force is transmitted to rotate. Drive motor
M represents the photosensitive drums 23Y, 23M, 23C, and 23K.
The direction of the arrow in FIG. 1 (counterclockwise
Direction). The image forming apparatus 100 includes a photosensitive drum 23
Primary band for charging Y, 23M, 23C, 23K
Stations Py, Pm, Pc, P
k, four injection chargers 24Y, 24M, 24C, 24
K is provided. Each injection charger 24Y, 24M, 24
C, 24K are charging sleeves 24YS, 2K as charging members.
4MS, 24CS, 24KS. The image forming apparatus 100 includes a scanner 2
7Y, 27M, 27C, 27K to photosensitive drum 23Y,
Irradiation of exposure light to 23M, 23C, 23K, uniform band
Of the charged photosensitive drums 23Y, 23M, 23C, 23K
By selectively exposing the surface, the photosensitive drum 23 is exposed.
Y, 23M, 23C, 23K on the surface according to the image signal
An electrostatic latent image is formed. Further, the image forming apparatus 100 includes a photosensitive drum
Electrostatic latent images formed on 23Y, 23M, 23C, 23K
Station as a developing means 25 for visualizing
Yellow (Y), magenta for each of Py, Pm, Pc and Pk
(M), cyan (C) and black (K)
Equipped with four developing units 25Y, 25M, 25C, 25K
I have. For each developing unit 25Y, 25M, 25C, 25K
Means that the developer is supplied to the photosensitive drums 23Y, 23M, 23C, 23
Developing member that transports toner to K and supplies toner included in the developer
(Developer carrier) as developing sleeves 25YS, 25YS
MS, 25CS, 25KS are provided. In addition, each
Of the developing units 25Y, 25M, 25C and 25K
It is attached detachably. Then, the image forming apparatus 100 performs the intermediate transfer.
The body 12 is an endless base wrapped around a plurality of rollers.
Is used. The intermediate transfer body 12 includes a photosensitive drum 23
Y, 23M, 23C, 23K, color image
During image formation, in the direction of the arrow (clockwise) in FIG.
As the photosensitive drums 23Y, 23M, 23C, and 23K rotate.
Rotate (circular movement). And the image shape
The forming apparatus 100 includes respective photosensitive drums 23Y, 23M, 23
Primary transfer row as primary transfer means for C and 23K
Rollers 26Y, 26M, 26C, and 26K are opposed to each other.
At the shooting position (primary transfer section) T1, each station P
The monochrome toner image formed by y, Pm, Pc, and Pk is
The images are sequentially transferred onto the rotating intermediate transfer body 12 in a superimposed manner. That
Thereafter, the image forming apparatus 100 rolls over the intermediate transfer body 12.
The transferred multicolor toner image is transferred to a transfer position (secondary transfer portion) T2.
, A secondary transfer roller 13 as a secondary transfer means,
By holding and transferring the transfer material 22 with the intermediate transfer body 12
Transfer to the transfer material 22. The transfer material 22 is, for example, a recording paper, an OHP
The image forming apparatus 100 is connected to the sheet feeding unit 11 or the like.
Feeds the transfer material 22 one by one from the
Secondary transfer section in synchronization with the formation of the toner image on
Transport to The image forming apparatus 100 is mounted on the transfer material 22.
While the multicolor toner image is being transferred to the
13 is brought into contact with the transfer material 22 at a position indicated by 13a in FIG.
At the end of the image forming process,
Separate. The fixing unit 14 serving as a fixing unit fixes the transfer material 22
The multicolor toner image transferred to the transfer material 22 while being transported
Is heated and fused. As shown in FIG.
In addition, the fixing unit 14 includes a fixing roller 1 that heats the transfer material 22.
5 for pressing the transfer material 22 against the fixing roller 15
And a pressure roller 29. Fixing roller 15
The pressure rollers 29 are formed in a hollow shape, and each has a heat roller inside.
Data 30 and 31 are incorporated. Fixing roller 15 and pressure
The roller 29 transfers the transfer material 22 holding the multicolor toner image.
Transport and apply heat and pressure to the transfer material 22.
Thus, the toner is fixed on the surface of the transfer material 22. The image forming apparatus 100 transfers a toner image.
After fixing to the transfer material 22, the transfer material 22 is provided outside the apparatus.
The paper is discharged to a paper discharge section 19 as a discharging means for forming an image.
End the operation. The cleaning means 32 includes an intermediate transfer member.
Intermediate transfer after transfer of toner image from 12 to transfer material 22
Cleaning the toner remaining on the body 12
You. In the cleaning unit 32, on the intermediate transfer body 12
Of the four-color multicolor toner image formed on the transfer material 22
The waste toner after the cleaning is stored in a cleaner container. The image forming apparatus 100 shown in FIG.
Density control optical sensor 40 capable of detecting the density of the toner image
Are arranged toward the intermediate transfer member 12, and the intermediate transfer member
Reference toner for controlling image density formed on the surface of No. 12
Image (toner density patch) pattern (toner density patch)
) Is measured. This density control light
2A and 2B show an example of the configuration of the chemical sensor 40. FIG. Dark
The degree control optical sensor 40 is an LED (light emitting diode)
And light emitting element 41, photodiode, Cds, etc.
Light receiving element 42 and the light receiving / emitting element
Optical element 43 and signal processing means for processing received light data
Such as an IC (not shown) and a housing for accommodating them.
(Not shown). The light receiving element 42 shown in FIG.
1 is a toner density patch pattern 4 via the optical element 43
4 both the regular reflection component and the irregular reflection component of the reflected light
Is detected. On the other hand, the light receiving element shown in FIG.
Reference numeral 42 denotes a state in which the light emitting element 41 receives the toner density via the optical element 43.
Reflection of reflected light when illuminating the patch pattern 44
It detects only diffuse reflection components without being affected by
You. Further, in the vicinity of the optical sensor 40 for density control, FIG.
No temperature and humidity sensors are installed,
You may comprise so that humidity and a temperature may be measured. As shown in FIG. 2A or FIG.
Density detection results using the optical sensor 40 for density control,
Density of image forming device based on detection result of temperature and humidity sensor
Control can be performed. However, the density control optical sensor 40
Density control of a toner image using the image forming apparatus 10
0 indicates that the toner density patch pattern 44 is
This is control to form and detect on top. Image forming apparatus 100
Transfer the toner image formed on the intermediate transfer body 12 to a transfer material
22 and is further fixed in the fixing unit 14.
However, the transfer efficiency in the transfer and the heating in the fixing
Depending on the state and the pressurized state,
The color balance of the toner image can vary.
You. Then, the transfer of the toner image to the transfer material 22 is performed.
After the operation and the fixing operation, the density of the toner image on the transfer material 22 is increased.
Or chromaticity, and detects the laser exposure and development bias.
Which process conditions can be switched or by laser exposure
An image signal on which an electrostatic latent image is formed on the photosensitive drum 23
Look-up table (LUT) for correcting signal
After the image signal is further corrected and fixed on the transfer material 22
The density and gradation characteristics (color balance) of
There is a way to keep it positive. Hereinafter, the present invention will be described with reference to the drawings.
The density or chromaticity of the toner image on the transfer material 22 is detected and the
How to maintain proper image density and gradation characteristics (color balance)
An embodiment of the method will be described. FIG. 3 is a schematic diagram of an image forming apparatus according to this embodiment.
It is a schematic diagram. As shown in FIG. 3, the image forming apparatus of this embodiment
The device 100 forms images on both sides of the transfer material 22.
To enable this, the reversing mechanism (switchback mechanism)
Part) reversing means having 17 and double-sided conveyance indicated by a chain line
A duplex unit 18 is provided as a means. In addition, both sides
The unit 18 is provided for the image forming apparatus 1 as required by the user.
Even if it is detachably attached to 00,
Provided as a part of the configuration of the image forming apparatus 100
It may be. The image forming apparatus 100 includes the fixing unit 14
The transfer path of the transfer material 22 after passing
To switch to a second direction different from the first direction
As a control means, a double-sided flapper 16 is provided. FIG.
Medium, double-sided flapper 16 lowered as shown by the solid line
When the transfer material 22 is at the position (16d), the transfer material 22 is
Conveyed (first conveyance direction), two-sided flapper 16
When it is in the raised position (16u) as shown by the chain line
The transfer material 22 is transported to the switchback mechanism 17.
(Second transport direction). Although not shown in FIG. 3, the present embodiment
, The station P, which is a plurality of image forming units,
To form a toner image on the intermediate transfer body 12 and transfer it to a transfer material.
Structure and operation of the image forming unit A for transferring the image to the image forming unit 22;
Configuration and operation of paper feed unit 11, transfer roller 13, and fixing unit 14
The operation is as described with reference to FIG. The image forming apparatus 100 of the present embodiment
As a step, a sensor capable of detecting the density and chromaticity of the toner image
(Hereinafter referred to as “color sensor”) 50. Color
An example of the sensor 50 is shown in FIG. 4A. Color sensor 50
Is a white LED 51 and an RGB on-chip filter
The load storage type sensor 52 is used. White LED 51
Is used as a reference toner for density or chromaticity control after fixing.
Image (toner patch) pattern (hereinafter referred to as “toner patch”
"Pattern". ) On the transfer material 22 on which 60 is formed
Incident at an angle of 45 degrees, and diffusely reflected light in the 0 degree direction
Charge storage type sensor with RGB on-chip filter
52. FIG. 4B is a diagram with an RGB on-chip filter.
FIG. 4A is a view of the charge storage type sensor 52 viewed from the direction of arrow A in FIG. 4A.
And a charge storage type sensor with an RGB on-chip filter.
The light receiving portion of the camera 52 has pixels with independent RGB.
It is. Charge storage type sensor with RGB on-chip filter
The charge storage sensor 52 of the sensor 52 is a photodiode.
Is also good. In FIG. 4B, as a set of three pixels of RGB,
However, it may be composed of several sets of pixels for each color.
In FIG. 4A, the incident angle of the white LED 51 with respect to the transfer material is shown.
Was set to 45 degrees, and the incident angle was set to 0 degrees, and the reflection angle was set to 45 degrees.
Charge storage type with RGB on-chip filter
The sensor 52 may be provided. Furthermore, the color sensor
With LED that emits three colors of RGB and sensor without filter
The LED of each color blinks alternately to fill
An image may be detected with a sensor without a sensor. FIG. 5 shows the density or the density formed on the transfer material 22.
FIG. 3 is a diagram illustrating an example of a toner patch pattern 60 for controlling chromaticity.
It is. Normally, multiple monochrome images with different densities,
Different full-color images, such as different density or chromaticity
A plurality of toner patches are continuously formed. This toner
By detecting the density or chromaticity of the patch pattern 60,
The toner after fixing the toner image on the transfer material 22
Maintain proper image density and gradation characteristics (color balance)
It becomes possible. When the above-described color sensor 50 is used,
Transfer operation and fixing operation of the toner image onto the transfer material 22
The density or chromaticity of the toner image on the transfer material 22 after
Therefore, the color sensor 50 is placed on the transfer path of the transfer material 22.
And is disposed immediately after the fixing unit 14 (downstream in the transport direction).
Then, the periphery of the fixing unit 14 is radiated from the fixing unit 14
Affected by heat. That is, the temperature near the fixing unit 14 is high.
And optical elements such as lenses that constitute the color sensor 50
Deformation of sensor holder and white LED 51
Torque, light quantity, charge storage type with RGB on-chip filter
Due to changes in the spectral sensitivity characteristics of the sensor 52, the toner
Detection result of the density or chromaticity of the touch pattern 60 fluctuates
there is a possibility. Therefore, as shown in FIG.
The fixing unit 14 radiates 50 sufficiently away from the fixing unit 14.
Image formation by placing it in a location that is not affected by heat
The apparatus 100 includes a toner patch pattern formed on the transfer material 22.
Turn 60 is detected, and toner of stable color balance
-It is possible to control to form an image on the transfer material 22.
Wear. FIG. 6 shows an image forming apparatus 10 according to this embodiment.
FIG. 4 is a block diagram showing a control configuration of 0. The image forming apparatus 100 operates as an image processing unit.
Image processing controller (image processing controller) 101
And a personal computer communicably connected to the main unit.
External host device such as computer or image forming device
Image signal from a document reading unit (not shown) provided separately
To the image forming control unit 103 described later.
A signal for image formation is transmitted. The image forming apparatus 100 changes the image signal.
LUT 102, which is a table for converting
The image signal received by the control unit 101 is exposed by laser exposure.
The image signal on which the electrostatic latent image is formed on the drum 23
Used to correct. Further, the image forming apparatus 100 includes control means
Forming control section for controlling each section of the image forming apparatus
(Image forming controller) 103, primary charging means
24, developing means 25, primary transfer means 26, etc.
The control unit controls the forming unit A, the fixing unit 14, and the color sensor 50.
You. The density or chromaticity detected by the color sensor 50, etc.
Information is input to the image forming control unit 103.
The image processing control unit 10 via the image formation control unit 103
LUT 10 which is input to 1 and is used for correcting an image signal
2 is used as information for adjusting. Also, image type
The formation control unit 103 includes the photosensitive drum 23, the intermediate transfer body 12,
Fixing roller 15 and paper discharge unit 19, switchback mechanism
Transport row on the transport path of the transfer material 22 provided at
A drive motor M for driving a motor (not shown) and the like is controlled.
In addition, one drive motor M is provided in common for each part,
May be switched as appropriate, or multiple motors may be used.
And may be controlled independently. Next, the image forming apparatus 10 in the present embodiment
0 is described with reference to the flowchart of FIG.
I do. FIG. 7 shows a toner patch on one side of the transfer material 22.
Image forming apparatus 1 for detecting by forming pattern 60
10 is a flowchart showing the operation of the 00. In step S701, the image forming control unit 10
3 controls density or chromaticity from the image processing control unit 101;
Upon receiving the control command to the effect that it should be performed, step S70
In step 2, paper feeding of the transfer material 22 from the paper feeding unit 11 is started. Then, in step S703, the image forming control
The control section 103 is provided on the front surface (first surface) of the transfer material 22.
As described above, the toner is caused by the action of the secondary transfer roller 13.
Transfer the image. Further, in step S704, the image forming control unit
Reference numeral 103 denotes a toner that is used to convey the transfer material 22 to the fixing unit 14 and
The image is fused and fixed to the transfer material 22. In step S705, the image forming control unit 10
3 is a position where the front end of the flapper 16 is raised.
(16u in FIG. 3) and the toner
The transfer material 22 on which the image is formed is transferred to the switchback mechanism 1
7 and cut from D1 direction to D2 direction in FIG.
Replace and flip. In step S706, the image forming control unit 10
3 is a transfer inverted by the switchback mechanism 17
The material 22 is transported in the duplex unit 18. In step S707, the color sensor 50
Indicates that the transfer material 22 is being transported to the secondary transfer portion T2.
At the detection position of the color sensor 50, the toner patch pattern
Image processing control unit 101
From the color sensor 50 via the image forming control unit 103
LUT 102 is adjusted based on the detection result received by
You. In step S708, the image forming control unit 10
3 is a double-sided paper for discharging the transfer material 22 to the paper discharge unit 19.
Move the flapper 16 to the position where the flapper tip is lowered (see FIG. 3).
16d) to transfer the transfer material 22 to the discharge unit 1
Discharge to 9. Here, image forming control is performed in step S707.
Color image compensation performed by the image processing control unit 101
The normal control will be described with reference to FIGS. First, the toner patch pattern shown in FIG.
The operation 60 will be described in detail. This toner patch pattern
Is composed of only one color of black (K) toner.
Gray tone patch 61 (61a, 61b, 6
1c, 61d, 61e), yellow (Y), magenta
Process gray that mixes three colors (M) and cyan (C)
The gradation patch 62 (62a, 62b, 62c, 62d, 6
2e). The process gray gradation patch 62a is a single color
It is formed to have the same chromaticity as the gray gradation patch 61a.
The transfer direction of the transfer material 22 (arrow in FIG. 5)
Along B), continuously to the monochromatic gray gradation patch 61a
Is formed. Similarly, process gray tone patch 6
2b and monochrome gray gradation patch 61b, process gray level
Tone patch 62c and monochrome gray tone patch 61c,
Sgray gradation patch 62d and single color gray gradation patch 61
d, Process gray gradation patch 62e and single color gray gradation
The patch 61e is also shaped so that each chromaticity is the same.
It was made. Then, the monochrome gray gradation patch 6
1 (61a, 61b, 61c, 61d, 61e)
Indicates different gradations (densities).
5 along the transport direction (in the direction of arrow B in FIG. 5).
(Along), the gradation (density) is gradually increased. Also,
Process gray tone patch 62 (62a, 62b, 62
c, 62d, 62e) are also the same
Similarly, gradually increase the gradation (density) along the transport direction.
It is. As described above, a pair of monochrome gray gradation
H 61 and the process gray gradation patch 62
The mixing amounts of the Y, M, and C color toners are adjusted so that the degrees are the same.
Although it is desirable to be set, it is formed on the transfer material 22.
Single gray tone patch 61 and process gray tone patch 61
The chromaticity of the helix 62 does not always match. So, image formation
The apparatus 100 includes a monochrome gray gradation patch 61 and a process group.
The color sensor is adjusted so that the chromaticity of the ray gradation patch 62 matches.
In step 50, a single color gray gradation patch 61 and a process gray level
Y, M, C3 based on the result of detecting the patch 62
Adjust the mixing amount of color toners, that is, the density of each color toner appropriately.
Adjust. FIG. 8 shows that the image forming apparatus 100
Based on the detection result of the sensor 50, the toner of the three colors Y, M and C
-Adjust the LUT 102 so that the mixing amount is appropriate.
5 is a flowchart showing the operation. In step S801, the color sensor 50
Indicates that a toner patch pattern 60 for chromaticity control is formed.
And a single-color gray image on the transfer material 22 that has passed through the fixing unit 14.
The chromaticity of the gradation patch 61a is detected. In step S802, the color sensor 50
Detects the chromaticity of the process gray gradation patch 62a.
You. In step S803, the image forming control unit 10
3 is the detection in step S801 and step S802
From the results, the chromaticity and process of the
The chromaticity difference of the gray tone patch 62a is within a predetermined value (for example,
If it is within ΔE3, which is within the color difference allowed by humans)
Relative comparison. In step S 803, the monochrome gray gradation patch
61a and the process gray gradation patch 62a
If it is determined that it is within the fixed value, step S804
Then, the image processing control unit 101 sets the process gray gradation patch
62a is achromatic and has the same gradation (density)
It is determined that the operation for adjusting the LUT 102 is not performed.
Proceed to the next step. On the other hand, in step S 803, the monochrome gray gradation
Chromaticity of patch 61a and process gray gradation patch 62a
If it is determined that the difference is not within the predetermined value, step S8
In step 05, the image processing control unit 101
Switch 62a determines that the chromatic color or gradation (density) is different.
You. Then, in step S806, the image forming apparatus 100
Is the yellow constituting the process gray gradation patch 62a.
-(Y), magenta (M) and cyan (C)
Adjust the correction coefficient of the LUT 102 to adjust the
Perform the adjustment operation. In addition, about adjustment of LUT102
Will be described later in detail with reference to FIG. In step S807, the image forming control unit 10
3 is a single-color gray floor to be detected by the color sensor 50 next.
Tone patch 61 and process gray tone patch 62
Is determined, and if YES, the process proceeds to step S801.
Return and perform the subsequent steps. By repeating the above steps,
The color sensor 50 includes a monochrome gray gradation patch 61a and a
Following the pair of process gray tone patches 62a,
H pairs 61b and 62b, 61c and 62c, 61d and
62d, 61e and 62e, and the image forming processing unit 1
01 is the LUT 102 for each of a plurality of gradations.
Make adjustments. In the above description, the color sensor
50 indicates a monochromatic gray gradation patch 61 and a process gray level
Each time a pair of adjustment patches 62 is detected, the image processing controller
101, the correction process is executed.
First, all patches 61 (61a, 61b, 61c, 61
d, 61e), 62 (62a, 62b, 62c, 62)
d, 62e) and then collectively process
The gray gradation patch 62 has an achromatic color and a gradation (density)
It may be determined whether they are the same. In step S803, the process gray
The target for which the chromaticity of the gradation patch 62 was relatively compared was measured.
All the monochromatic gray gradation patches 61 (61a, 61b, 6
1c, 61d, and 61e). According to the adjustment method of LUT 102 described above,
The process gray gradation patch 62 is achromatic and
Can determine whether the tone (density) is the same,
Since the level can be known, paper dust, toner or
Effects of sensor contamination due to scattering of
High-accuracy concentration or density without being affected by variations in characteristics
Can detect enough data to perform chromaticity control
It works. Further, by adjusting the LUT 102,
Process that mixes three colors of yellow, magenta, and cyan
The mixing amount of the three colors at which the gray gradation patch 62 becomes achromatic is
The image processing control unit 1 appropriately adjusts a plurality of gradients.
01 to adjust image forming conditions
Thus, an image forming apparatus having good density-gradation characteristics can be provided. FIG. 9 shows an image processing system of the image forming apparatus 100.
Flowchart showing an example of image processing in the control unit 101
It is. The color matching table shown in FIG.
, Color separation table, calibration table, P
Each correction table of the WM table is stored in the image processing controller 10.
It is assumed that one LUT 102 is included. In step S901, the image processing control unit 10
1 is the color matching table prepared in advance
From an external host device such as a personal computer
The RGB signal representing the color of the transmitted image is corrected by a predetermined correction unit.
The color reproduction range of the image forming apparatus is corrected by calculation using numbers.
Device RGB signal (hereinafter referred to as DevRGB)
To). In step S902, the image processing controller 10
1 is De based on a color separation table prepared in advance.
Correction of vRGB signal by calculation using predetermined correction coefficient
Then, the CMYK signal, which is the toner color material color of the image forming apparatus, is used.
Convert. In step S903, the image processing control unit 10
1 complements the density-gradation characteristics unique to each image forming apparatus.
The CMYK signal is
By calculating the signal using a predetermined table, the concentration
-Conversion to C'M'Y'K 'signal with gradation characteristic correction
I do. In this conversion, a plurality of gradations (for example, a
To 5e) to the C signal and the C signal.
The C 'signal is stored in the calibration table of the LUT 102
And store the input C signal.
A conversion method using the C signal and the C ′ signal is used. A specific example will be described.
The C signal and the corresponding C ′ signal are Ca and C ′.
a, Cb and C'b, Cc and C'c, Cd and C'd, Ce
Are stored in the LUT 102 in advance as
When converting the input C signal into a C ′ signal, the LUT 1
02 using the value stored in the calibration table
I have. Then, for example, a gradation f between the gradation a and the gradation b
Is input as Cf which is a C signal, LUT1
02 stored in the calibration table 02
Using C′a, Cb and C′b, the following equation (1) is used.
The signal is converted into a C'f signal by linear interpolation. C′f = Cf · (C′a−C′b) / (Ca−Cb) + (Cb · C′a−Ca · C′b) / (Cb−Ca) (1) In the above, the conversion from the C signal to the C ′ signal is performed.
Although the conversion has been described, the conversion from the M signal to the M ′ signal is performed.
The same applies to the conversion from the Y signal to the Y 'signal.
Can be used for linear interpolation. In addition, besides linear interpolation
Needless to say, various interpolation methods can be used.
No. At step S904, PWM (pulse width change)
Tone: Pulse Width Modulation)
The C′M′Y′K ′ signal is converted into a predetermined correction signal by a table.
Corrected by arithmetic using numbers, and converted to C'M'Y'K 'signals
The corresponding scanner units 27C, 27M, 27Y, 27K
The exposure time is converted into Tc, Tm, Ty, Tk. With the above steps, from the external host device
The input image signal is subjected to laser exposure in the scanner unit 27.
It has been converted to light time. Then, in step S806 in FIG.
As the correction of the LUT 102, step S903 in FIG.
Adjustment of the calibration table used in step. Ki
From CMYK signal using calibration table
In the conversion to the C'M'Y'K 'signal,
C for a plurality of gradations (for example, five gradations a to e)
Signal and C 'signal for LUT102 calibration
This is stored as a table. So,
To adjust the calibration table,
(For example, five gradations a to e)
And the value of the C ′ signal corresponding thereto. For example,
The color sensor 50 controlled by the image forming control unit 103
In the tone a, the monochrome gray gradation patch 61a and the process
It is detected that the chromaticity difference of the ray gradation patch 62a is not within a predetermined value.
If it is known, the detection signal input from the color sensor 50
To the image forming processing unit 101 based on the
Concentration or to adjust the calibration table of
Send information about chromaticity. Image forming processing unit 101
Is based on the input information on density or chromaticity,
Stored as calibration table for LUT 102
The values of the Ca signal and the C′a signal thus changed are changed. In the above, the gradation a has been described.
However, for other gradations, carry
You can make adjustments to the braille table. or,
For Y and M colors other than C, carry in the same way.
Adjustment of the bration table is possible. By performing the above adjustment operation, each gradation
The mixing amount of C, M, and Y
-Chromaticity difference between the tone patch 62 and the monochrome gray tone patch 61
Is within a predetermined value. In the above description, the image processing control unit
101 is an LUT 102 (more specifically, an LUT 102
Calibration table) by adjusting the desired
Control method to obtain density or chromaticity
And explained. In another aspect, the image forming control unit
Reference numeral 103 denotes a density or chromaticity detection of the toner patch pattern 60.
After that, for example, exposure of laser light by the scanner unit 27
And the developing bias by the developing means 25 based on the detection result.
By directly controlling the density or chromaticity,
It is also possible to obtain a defined image. Other, color
The image forming operation is controlled based on the detection result of the sensor 50,
Choose a method to control the density or chromaticity of the image after fixing
You may be able to do it. The image forming control unit 103 is a color sensor.
Optical sensor 4 for density control separately provided from 50
0, the toner density pattern formed on the intermediate transfer body 12
Switch pattern 44, and switches according to the detection result.
Exposure amount of laser light by the canner part 27,
This is also applicable when performing the operation of controlling the developing bias by
Can be In this case, the density control optical sensor 4
0 for each of multiple gradations
The scanner unit 27 according to the corrected detection result.
Exposure amount of laser light, and development via by developing means 25
The amount of C, M, and Y can be adjusted by controlling
Process gray scale patch 62 and single color gray scale patch 62
The chromaticity difference of the switch 61 is within a predetermined value. The switchback mechanism 17 is provided with a transfer material.
22 transport routes and forward / reverse transport rollers (switches)
Transport means such as a back roller). Also, both sides
The unit 18 is transported from the switchback mechanism 17.
The transfer material 22 to be transferred is stored, and the
Storage section, transfer path of transfer material and transfer roller
Transport means. In this embodiment, the color sensor 50
A switchback mechanism in the transfer path of the transfer material 22.
Between the portion 17 and the transfer roller 13 (that is, the secondary transfer portion T2).
Between the toner patch patterns 60
I do. More specifically, as shown in FIG.
On the road, the transfer material 22 passes through the duplex unit 18
From the position to the transfer position of the secondary transfer portion T2.
It is preferable to dispose the sensor 50. Here, the conveyance control is performed by the image forming apparatus 100.
The transfer path of the transfer material 22 to be controlled will be described with reference to FIG.
Will be explained. FIG. 10 shows the transfer material 22 in this embodiment.
It is a flowchart which shows a conveyance path. The transfer material 22 is supplied
The paper is conveyed from the paper unit 11 to the transfer roller 13 (S1001,
S1002), reference development formed on intermediate transfer body 12
The toner patch pattern 60 as the agent image is transferred,
The toner patch is transferred onto the transfer material 22 by passing through the
The pattern 60 is fused and fixed (S1003). Next
The transfer material 22 on which the toner patch pattern 60 is formed
The switchback mechanism 17 is controlled by the double-sided flapper 16.
(S1004, S1005), the double-sided unit
To the position of the color sensor 50 via the port 18 (S
1006, S1007). And the color sensor 50
The density or chromaticity of the toner patch pattern 60 is detected. Density or chromaticity of toner patch pattern 60
Is detected, the transfer material 22 is transferred to the transfer roller 13 (S100).
2), fixing unit 14 (S1003), double-sided flapper 16
The paper is discharged to the paper discharge unit 19 via (S1004) (S1004).
1008). As described above, the features of this embodiment are as follows.
A switchback machine for transferring the color sensor 50 to the transfer material transport path
That it is located between the structure 17 and the transfer roller 13;
Density of the toner patch pattern 60 by the color sensor 50
Alternatively, in order to detect chromaticity, the transfer material 22 is
After wearing, the switchback mechanism 17 and the double-sided unit 18
Transfer to the position of the color sensor 50 and transfer after detection
Conveyed to the paper output unit 19 via the roller 13 and the fixing unit 14
To make it happen. In this embodiment, the switchback mechanism 17 and
If the image forming apparatus has the duplex unit 18,
By arranging the color sensor 50 at a predetermined position,
It can be implemented without any change in the structure. Also, color
The sensor 50 is located at a sufficient distance from the fixing unit 14.
Is located at a position that is not affected by the heat radiated. Change
The transfer material 22 is fixed after the toner patch pattern 60 is fixed.
The time it takes to reach the position of the color sensor 50 from the
The transfer material 22 heated by the section 14 is
Temperature that does not cause deformation, change in characteristics, or decrease in reliability.
To allow enough time for cooling. The arrangement and transfer of the color sensor 50 of this embodiment
According to the conveyance path of the material 22, the color sensor 50 and the fixing unit
14 and the color sensor 50
While transferring the transfer material 22 to the position, the temperature of the transfer material 22
As the temperature decreases, the heat radiated by the fixing unit 14 and the transfer material 22
The color sensor 50 is not affected by heat. Therefore, according to this embodiment, high precision and
Highly reliable density or chromaticity control can be performed
You. (Second Embodiment) Next, a second embodiment of the present invention will be described.
Will be described. This embodiment is similar to the first embodiment in the configuration shown in FIG.
The toner patch pattern on both sides of the transfer material 22
60 are formed, and the toner patch patterns 60 on both sides are formed.
The difference is that the density or chromaticity is detected by the color sensor 50.
Become. Hereinafter, the image forming apparatus 10 according to the present embodiment will be described.
0, referring to the flowchart of FIG.
explain. FIG. 11 shows a toner package on both surfaces of the transfer material 22.
Forming Apparatus for Forming and Detecting Hatch Pattern 60
4 is a flowchart showing the operation of the embodiment of FIG. In step S1101, the image forming control unit 1
03: control of density or chromaticity from the image processing control unit 101
When a control command indicating that the operation should be performed is received, step S1 is executed.
At 102, the feeding of the transfer material 22 from the sheet feeding unit 11 is started.
You. Then, in step S1103, an image is formed.
The control unit 103 sets the front surface (first surface) of the transfer material 22
As described above, the toner is generated by the action of the secondary transfer roller 13.
-Transfer the image. In step S1104, image formation control is performed.
The unit 103 transports the transfer material 22 to the fixing unit 14 and
-Fusing the image to the transfer material 22; In step S1105, the image forming control unit 1
03: Double-sided flapper 16 with flapper tip raised
(16u in FIG. 3).
-The transfer material 22 on which the image is formed is transferred to the switchback mechanism.
17 and cut from the D1 direction to the D2 direction in FIG.
Swap and flip. In step S1106, the image forming control unit 1
The reference numeral 03 denotes a reverse rotation by the switchback mechanism 17.
The copying material 22 is transported in the duplex unit 18. In step S1107, the color sensor 50
Indicates that the transfer material 22 is being transported to the secondary transfer portion T2.
At the detection position of the color sensor 50, the toner patch pattern
Image density or chromaticity of the image
The control unit 101 is configured to switch from the color sensor 50 to an image forming control unit.
103 based on the density or chromaticity detection result received via
Then, the correction coefficient of the LUT 102 is adjusted. In step S1108, image forming control unit 1
03 indicates that the color sensor 50 detects that the rear surface of the transfer material 22 (the second
Whether or not the toner patch 60 formed on the
If it is determined that only the first side is detected (step S1
108, NO), the process proceeds to step S1103, and the transfer material is
Transfer of the toner patch 60 to the back surface (second surface)
After that, the operations of steps S1104 to S1107 are performed.
Do. In step S1108, the second side has already been detected.
If it is known (YES in step S1108),
Proceeding to step S1109, the image forming control unit 103
In order to discharge the transfer material 22 to the paper discharge portion 19,
Position the flapper 16 at the position where the tip of the flapper is lowered (see FIG. 3).
16d), and the transfer material 22 is
To drain. In step S1107, the image forming control unit
103 and the density or chromaticity performed by the image processing control unit 101.
The control is the same as that described in the first embodiment.
The description is omitted. In the above description, the image processing control unit
101 adjusts the LUT 102 to obtain a desired density or density.
Explains how to control so that chromaticity can be obtained.
Revealed. As another mode, the image forming control unit 103
After detecting the density or chromaticity of the toner patch pattern 60,
For example, the exposure amount of the laser beam by the scanner
The developing bias by the means 25 is directly determined by the detection result.
By controlling the density or chromaticity, the stable image
It is also possible to obtain an image. Other, color sensor 50
Controls the image forming operation based on the detection result of
Selecting a method for controlling the density or chromaticity of the image as appropriate
You may be able to do. The image forming control unit 103 is a color sensor.
Optical sensor 4 for density control separately provided from 50
0, the toner density pattern formed on the intermediate transfer body 12
Switch pattern 44, and switches according to the detection result.
Exposure amount of laser light by the canner part 27,
This is also applicable when performing the operation of controlling the developing bias by
Can be In this case, the density control optical sensor 4
0 for each of multiple gradations
The scanner unit 27 according to the corrected detection result.
Exposure amount of laser light, and development via by developing means 25
The amount of C, M, and Y can be adjusted by controlling
As a result, the process gray tone patch 62 becomes achromatic. The feature of this embodiment is the same as that of the first embodiment.
And control the density or chromaticity of both sides during double-sided image formation
And the method of transporting the transfer material 22 therefor
is there. Note that the image processing control unit 101 controls the
-When the patch pattern 60 is formed,
If the same image is formed on the back side, the color may differ slightly.
Transfer material 2 so that appropriate density or chromaticity control can be performed
LUT1 separately for each of the front and back of 2
02 correction coefficient is prepared, and the front side (first side) and the back side
Correction coefficient of LUT 102 provided for each (second surface)
May be adjusted. Further, the image forming control unit 103 controls the transfer material 22
Toner patch patterns 60 with different gradations on both sides of
A toner patch pattern formed and used for adjusting the LUT 102
The correction accuracy can be increased by increasing the number of turns.
In this case, the gradation can be adjusted by the LUT 102.
The toner patch pattern 60 only on the front side (first side).
Is twice as large as when forming
Adjustments can be made. Arrangement and transfer of color sensor 50 of this embodiment
Formation of a toner patch pattern 60 on both surfaces of the material 22;
According to the transfer method (the transfer path of the transfer material 22),
The distance between the sensor 50 and the fixing unit 14 is large, and
While transferring the transfer material 22 to the position of the color sensor 50
Since the temperature of the transfer body 22 decreases, the fixing unit 14 emits light.
Of the transfer material 22 and the heat of the transfer material 22
And the density or density of both sides during double-sided image formation.
Enables chromaticity control. (Third Embodiment) Next, a third embodiment of the present invention will be described.
Will be described. FIG. 12 shows an image forming apparatus 1 according to this embodiment.
FIG. In this embodiment, the color sensor
The toner pack 50 is placed in the switchback mechanism 17.
The first implementation is that it is arranged toward the formation surface of the
Different from the example. Other configurations are the same as those of the first embodiment. As shown in FIG. 12, the image forming of this embodiment
The apparatus 100 controls the transfer material 22 after passing through the fixing unit 14.
Double-sided flash
And the first and second switchback flapper 20
a and 20b. In FIG. 12, the double-sided flapper 16 is
In the lowered position (16d) as shown by the line
The switchback flapper 20b is shown on the left side by the two-dot chain line.
When the transfer material 22 is at the position (20bl),
(First transport direction), two-sided flapper
It is at the raised position (16u) as shown by the dashed line.
1 switchback flapper 20a indicated by a two-dot chain line
When in the side position (20al), the transfer material 22 is
The sheet is transported to the back mechanism 17 (second transport direction). In this embodiment, the image forming control unit 103
Are the first and second switchback flappers 20a, 20b
By controlling the switchback mechanism 17
To the paper output unit 19 without passing through the duplex unit 18.
And the transfer material 22 can be transported. In addition, switch
Transfers the transfer material 22 from the back mechanism 17 to the paper discharge unit 19
In this case, the first and second switchback flapper 20
a, 20b are at the right side position (20a
r, 20 br). Hereinafter, the image forming apparatus 10 according to the present embodiment will be described.
0 is described with reference to the flowchart of FIG.
I will tell. FIG. 13 shows the toner package on one side of the transfer material 22.
Forming Apparatus for Forming and Detecting Hatch Pattern 60
4 is a flowchart showing the operation of the embodiment of FIG. In step S1301, the image forming control unit 1
03 denotes a toner patch pattern from the image processing control unit 101.
When a signal to the effect that a button 60 is to be formed is received, step S
In step 1302, feeding of the transfer material 22 from the sheet feeding unit 11 is started.
Let In step S1303, an image is formed.
The control unit 103 sets the front surface (first surface) of the transfer material 22
As described above, the toner is generated by the action of the secondary transfer roller 13.
-Transfer the image. Further, in step S1304, the image forming control
The control unit 103 transports the transfer material 22 to the fixing unit 14 and
The toner image is fused and fixed to the transfer material 22. In step S1305, image forming control unit 1
03: Double-sided flapper 16 with flapper tip raised
(16u) to form a toner image.
The transferred transfer material 22 is transported to the switchback mechanism 17.
The toner patch at the detection position of the color sensor 50.
In addition to detecting the density or chromaticity of the pattern 60,
The processing control unit 101 receives an image forming control signal from the color sensor 50.
The detection result of the density or chromaticity received via the control unit 103
Based on the above, the LUT 102 is adjusted. In step S1306, the transfer material 22 is
The transfer direction of the transfer material 22 is changed to the direction D1 in FIG.
Switch to D3 direction, switch back flapper 2
0a and 20b. After that, in step S1307, the image format
The formation control unit 103 causes the transfer material 22 to be discharged to the paper discharge unit 19.
You. In step S1305, the image forming control unit
103 and the density or chromaticity performed by the image processing control unit 101.
The control is the same as that described in the first embodiment.
The description is omitted. In the above description, the image processing control unit
101 adjusts the LUT 102 to obtain a desired density or density.
Explains how to control so that chromaticity can be obtained.
Revealed. As another mode, the image forming control unit 103
After detecting the density or chromaticity of the toner patch pattern 60,
For example, the exposure amount of the laser beam by the scanner
The developing bias by the means 25 is directly determined by the detection result.
By controlling the density or chromaticity, the stable image
It is also possible to obtain an image. Other, color sensor 50
Controls the image forming operation based on the detection result of
Selecting a method for controlling the density or chromaticity of the image as appropriate
You may be able to do. The image forming control unit 103 is a color sensor.
Optical sensor 4 for density control separately provided from 50
0, the toner density pattern formed on the intermediate transfer body 12
Switch pattern 44, and switches according to the detection result.
Exposure amount of laser light by the canner part 27,
This is also applicable when performing the operation of controlling the developing bias by
Can be In this case, the density control optical sensor 4
0 for each of multiple gradations
The scanner unit 27 according to the corrected detection result.
Exposure amount of laser light, and development via by developing means 25
The amount of C, M, and Y can be adjusted by controlling
As a result, the process gray tone patch becomes achromatic. Further, the color sensor 50 is provided with a switchback.
In the mechanism 17, the surface on which the toner patch pattern 60 is formed
It is arranged as shown in FIG.
You. Here, the image formation controlled as shown in FIG.
Transfer path of the transfer material 22 controlled by the apparatus 100
Will be described with reference to FIG. FIG.
5 is a flowchart illustrating a transfer path of the transfer material 22 in the example.
It is. Transfer material 22 is supplied from paper feed unit 11 to transfer roller 13
The intermediate transfer body 12 is transported (S1401, S1402).
The toner patch pattern 60 formed thereon is transferred,
As the toner passes through the fixing section 14, the toner
The first pattern 60 is fused and fixed (S1403). Next
The transfer material 22 on which the toner patch pattern 60 is formed
The switchback mechanism 17 is controlled by the double-sided flapper 16.
(S1404, S1405), and
The color sensor 50 in the printing mechanism 17 is
The density or chromaticity of the turn 60 is detected. The density or chromaticity of the toner patch pattern 60
Is detected, the transfer material 22 has two switchback flapper
The paper is ejected to the paper ejection unit 19 by 20a and 20b (S1).
408). As described above, the features of this embodiment are as follows.
The color sensor 50 is arranged in the switchback mechanism 17.
And the transfer material 22 is once switched back to the switchback mechanism 1
7 and, after detecting the density or chromaticity,
Switchback without passing through the
The paper is conveyed to the paper discharge unit 19 through the wrappers 20a and 20b.
Is to do. As described above, the image in the first embodiment
As compared with the operation of the forming apparatus 100, whether the transfer material 22 is fed
The length of the transport path from the discharge to the discharge can be shortened. As shown in FIG. 12, the image forming of this embodiment
The device 100 has the switchback mechanism 17 and
And a double-sided unit 18 similar to that of the first embodiment.
An image can be formed on both surfaces of the material 22. Only
However, in this embodiment, the image forming apparatus does not employ the duplex unit.
The switchback mechanism 17 and the switch
Switchback flappers 20a and 20b are provided and switches
Arranging the color sensor 50 in the back mechanism 17
Can be implemented. Also, the color sensor 50 is
Sufficiently distant, not affected by heat radiated by fixing unit 14
Is located in the position. Further, the transfer material 22 is
Reaches the position of the color sensor 50 after the fixing of the pattern 60
The transfer material heated by the fixing unit 14
22 is the deformation and characteristic change of the color sensor 50,
Sufficient time to cool to a temperature that does not
I am trying to. Moreover, in this embodiment, the first embodiment
The transfer distance of the transfer material 22 is shorter than that of
The time required for the control operation is shorter than in the first embodiment. The arrangement and transfer of the color sensor 50 of this embodiment
According to the conveyance path of the material 22, the color sensor 50 and the fixing unit
14 and the color sensor 50
While transferring the transfer material 22 to the position, the temperature of the transfer material 22
As the temperature decreases, the heat radiated by the fixing unit 14 and the transfer material 22
The color sensor 50 is not affected by heat,
Also provided switchback flappers 20a and 20b
By shortening the transport path of the copying material 22, the density can be reduced in a short time.
The degree or chromaticity detection is completed. Therefore, according to this embodiment, high precision and
Perform reliable density or chromaticity control in a short time.
Can be. (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
Will be described. This embodiment is the same as the third embodiment shown in FIG.
The toner patch pattern is formed on both sides of the transfer material 22.
The toner patch patterns 60 on both sides are formed.
Is that the density or chromaticity of
different. Hereinafter, the image forming apparatus 10 according to the present embodiment will be described.
0 will be described with reference to the flowchart of FIG.
I will tell. FIG. 15 is a view showing a toner package on both surfaces of the transfer material 22.
Forming Apparatus for Forming and Detecting Hatch Pattern 60
4 is a flowchart showing the operation of the embodiment of FIG. In step S1501, the image forming control unit 1
03 denotes a toner patch pattern from the image processing control unit 101.
When a signal to the effect that a button 60 is to be formed is received, step S
In step 1502, feeding of the transfer material 22 from the sheet feeding unit 11 is started.
Let Then, in step S1503, an image is formed.
The control unit 103 sets the front surface (first surface) of the transfer material 22
As described above, the toner is generated by the action of the secondary transfer roller 13.
-Transfer the image. Further, in step S1504, the image forming control
The control unit 103 transports the transfer material 22 to the fixing unit 14 and
The toner image is fused and fixed to the transfer material 22. In step S1505, the image forming control unit 1
03: Double-sided flapper 16 with flapper tip raised
(16u) so that the toner image is formed.
The transferred transfer material 22 is transported to the switchback mechanism 17.
The toner patch at the detection position of the color sensor 50
In addition to detecting the density or chromaticity of the pattern 60,
The processing control unit 101 receives an image forming control signal from the color sensor 50.
The detection result of the density or chromaticity received via the control unit 103
Based on the above, the LUT 102 is adjusted. In step S1506, the image forming control unit 1
03 controls the transfer material 22 by controlling the switchback mechanism 17;
Is switched and reversed. In step S1507, the back of the transfer material 22 is
The toner patch pattern 60 formed on the surface (second surface)
It is determined whether or not the second side has been detected.
If not (NO in step S1507), step S15
03, and returns to steps S1503 to S1507.
Perform control. That is, the image forming control unit 103 sets the transfer row
Toner on the back surface (second surface) of the transfer material 22 when passing through the
The patch pattern 60 is transferred (step S1503),
When the toner patch pattern 6 is passed through the fixing unit 14,
0 is fused and fixed (step S1504), and the transfer material 22 is fixed.
Of the toner patch pattern 60 on the back surface (second surface) of the
And adjust the LUT 102 based on the detection result.
(Step S1505), cutting the transfer direction of the transfer material 22
Instead, it is inverted (step S1506). In step S1507, the two surfaces of the transfer material 22
If it is determined that the eyes have already been detected,
Proceed to step S1508. In step S1508, the image forming control unit
103 discharges the transfer material 22 to the paper discharge unit 19. In the above description, the image processing control unit
101 adjusts the LUT 102 to obtain a desired density or density.
Explains how to control so that chromaticity can be obtained.
Revealed. As another mode, the image forming control unit 103
After detecting the density or chromaticity of the toner patch pattern 60,
For example, the exposure amount of the laser beam by the scanner
The developing bias by the means 25 is controlled based on the detection result.
By performing density or chromaticity control, a stable image is obtained
It is also possible. In addition, detection of the color sensor 50
The image forming operation is controlled based on the
The method of controlling the degree or chromaticity can be selected as appropriate
You may do it. The image forming control unit 103 is a color sensor.
Optical sensor 4 for density control separately provided from 50
0, the toner density pattern formed on the intermediate transfer body 12
Switch pattern 44, and switches according to the detection result.
Exposure amount of laser light by the canner part 27,
This is also applicable when performing the operation of controlling the developing bias by
Can be In this case, the density control optical sensor 4
0 for each of multiple gradations
The scanner unit 27 according to the corrected detection result.
Exposure amount of laser light, and development via by developing means 25
The amount of C, M, and Y can be adjusted by controlling
As a result, the process gray tone patch 62 becomes achromatic. Note that the image processing control unit 101 controls the
-When the patch pattern 60 is formed,
When the same image is formed on the back side, the color is slightly different
Transfer material 22 so that appropriate density or chromaticity control can be performed.
LUT10 separately for each of the front side and back side
2 of the front side (first side) and the back side (second side)
The LUT 102 provided for each may be adjusted. Further, the image forming control unit 103 controls the transfer material 22
Toner patch patterns 60 with different gradations on both sides of
A toner patch pattern formed and used for adjusting the LUT 102
The correction accuracy can be increased by increasing the number of turns.
In this case, the gradation for adjusting the LUT 102 is
Form toner patch pattern 60 only on (first surface)
It is at least twice as large as
Key adjustments can be made. Here, the image formation controlled as shown in FIG.
Transfer path of the transfer material 22 controlled by the apparatus 100
Will be described with reference to FIG. FIG.
5 is a flowchart illustrating a transfer material transport path in an example.
You. The transfer material 22 is supplied from the paper feeding unit 11 to the transfer roller 1.
3 (S1601, S1602), and the intermediate transfer member
The toner patch pattern 60 formed on the transfer material 12
22 is transferred to the front surface (first surface) of
The toner patch pattern 60 is melted and fixed.
(S1603). Next, the toner patch pattern 60
The transfer material 22 on which the is formed is scanned by the double-sided flapper 16.
The sheet is transported to the switchback mechanism 17 (S1604, S1604).
1605), the color sensor in the switchback mechanism 17
The toner patch pattern 50 is formed on the front surface of the transfer material 22.
The density or chromaticity of the 60 is detected (S1606). The darkness of the toner patch pattern 60 on the front surface
After the detection of the degree or chromaticity, the image is transmitted via the duplex unit 18 (S
1607) The toner formed on the intermediate transfer body 12 again
Patch pattern 60 is applied to the back surface (second surface) of transfer material 22
After being transferred (S1602) and passing through the fixing unit 14,
The toner patch pattern 60 is fused and fixed (S160).
3). Next, the toner patch pattern 60 was formed.
Transfer material 22 is switched back by double-sided flapper 16
The sheet is transported to the structural unit 17 (S1604, S1605), and
The color sensor 50 in the switchback mechanism 17
Detects chromaticity (S1606). The density or density of the toner patch pattern 60 on the back
Indicates that the transfer material 22 has two switchback buffers after detecting the chromaticity.
The paper is discharged to the paper discharge unit 19 by the wrappers 20a and 20b.
(S1608). As described above, the features of this embodiment are as follows.
In addition to the features of the third embodiment, both
The density or chromaticity of the surface can be controlled, and
Of the density or chromaticity of the detected toner patch pattern 60
After the detection, the switchback flapper 20a, 20b
To the paper discharge unit 19 without passing through the image forming means A.
Since the copying material 22 is transported, the transfer material is compared with the second embodiment.
22 can be shortened. [0169] Arrangement and transfer of color sensor 50 of this embodiment
Formation and transfer of toner patch pattern on both sides of material 22
According to the conveyance path of the material 22, the color sensor 50 and the fixing unit
14 and the color sensor 50
While transferring the transfer material 22 to the position, the temperature of the transfer material 22
The heat of the fixing member 14 and the heat of the transfer material 22
Without affecting the color sensor 50, and on both sides
It is possible to control the density or chromaticity of both sides during image formation. Change
And switchback flappers 20a and 20b
By shortening the transport path of the copying material 22, the density can be reduced in a short time.
The degree or chromaticity detection is completed. Therefore, according to this embodiment, high accuracy and
Highly reliable density or chromaticity control for double-sided images
It can be implemented in a short time. In the first to fourth embodiments, the image forming
A means wherein the means A has a plurality of image forming portions and an intermediate transfer member;
When the present invention is applied to an Ndem type color image forming apparatus,
However, the present invention is not limited to this.
is not. As is well known to those skilled in the art,
Transfers images from multiple image carriers such as photoconductors to the
Image forming apparatus for sequentially transferring and fixing the toner images, or
Multi-color toner images on a single image carrier such as a photoconductor
Next, this toner image was carried on the transfer material conveying means.
Transfer the image onto the transfer material sequentially, or
After transferring the next layer, transfer it to the transfer material at once, and then
There is an image forming apparatus for fixing. Such image formation
The present invention can be similarly applied to the device, and
The effect of can be obtained. As described above, according to the above embodiment,
If the fixing device radiates heat,
Always high temperature and transfer material immediately after fixing
Affected by the heat caused by the higher temperatures and higher temperatures
Density or color of the image formed on the transfer material after fixing
Degree is detected stably with high accuracy and high reliability
Can be controlled. Further, according to the above embodiment, the above operation and effect can be obtained.
While playing, the image formed on the transfer material after fixing
Can detect and control density or chromaticity in a short time
Image formed on both sides of transfer material after fixing
Formation that can detect and control the density or chromaticity of the image
Device, and toner formed on both sides of the transfer material after fixing.
ー Detecting and controlling the density or chromaticity of an image in a short time
An image forming apparatus is provided. (Other Embodiments) The first to fourth embodiments described above
In the embodiment, an image forming apparatus using an electrophotographic method is used.
To form a toner patch pattern 60 on the transfer material 22
After fixing the toner patch pattern with the color sensor 50
The LUT 102 is adjusted by detecting the
Chromaticity and gradation are appropriately controlled. The present invention relates to an image forming method using the above electrophotographic method.
Image using inkjet method, not limited to
It is also possible to apply to a forming apparatus. That is, the recording medium
From an image forming means such as an ink head to an image signal.
By ejecting inks of a plurality of colors according to the
Ink patch, and use the ink patch as a color sensor
The color of the image is detected by adjusting at 50 and adjusting the LUT 102
The degree and the gradation can be controlled appropriately. In this case, the image formation of the ink head or the like is performed.
Means at the same position as image forming means A in FIGS.
3 and the color sensor 50 is
Transfer material from the print mechanism 17 to the image forming means A
The switchback mechanism 17 shown in FIG.
The same effect as in the first to fourth embodiments is obtained
Can be obtained. In addition, in the inkjet method
In the image forming apparatus, the fixing unit 14 shown in FIGS.
It is considered that both the case where the
It is. The present invention is not limited to the above embodiment.
Without departing from the scope of the appended claims, various modifications are possible.
Needless to say. As described above, according to the present invention,
Density of toner image fixed on transfer material by fixing means
Or, it is a detecting means for detecting chromaticity at a predetermined detection position.
When the transfer material passes through the double-sided
Is a predetermined position on the transport path from the end to the transfer position.
Detecting means and an image forming device based on a detection result of the detecting means.
Control means for controlling the step, so that the fixing means emits radiation.
Forming on transfer material without being affected by heat of transfer material or heat of transfer material
Detected image, and appropriately control the density or chromaticity of the image.
An image forming apparatus can be provided. Further, according to the present invention, the image is transferred by the fixing means.
The density or chromaticity of the toner image fixed on the
Detecting means for detecting at a known position;
Means for detecting a predetermined position in the reversing mechanism,
Control means for controlling the image forming means based on the detection result of the step
With a step, the fixing unit can absorb the heat radiated by the fixing
Detects the image formed on the transfer material without being affected by
Image forming apparatus for appropriately controlling the density or chromaticity of an image
Can be provided. Furthermore, according to the present invention, the image forming means
The chromaticity of the image formed on the recording medium
Detection means, and the predetermined detection position is
The transport direction of the recording medium is changed to the second
The transport in which the recording medium is transported after switching to the transport direction
On the transport path, at a predetermined position up to the image forming unit
An image consisting of a certain detecting means and a plurality of colors detected by the detecting means.
To adjust the density of each color of multiple colors based on the chromaticity of the image
And a control unit for controlling the image forming unit.
Record without being affected by the heat radiated by the
Detects the image formed on the recording medium and determines the density or color of the image.
Can provide an image forming apparatus that appropriately controls the degree
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an image forming apparatus using an electrophotographic method. FIG. 2 is a schematic diagram of a density control optical sensor used in the image forming apparatus. FIG. 3 is a schematic diagram of an image forming apparatus according to first and second embodiments of the present invention. FIG. 4 is a schematic diagram of a color sensor used in the image forming apparatus. FIG. 5 is a diagram illustrating an example of a toner patch pattern for density or chromaticity control formed on a transfer material. FIG. 6 is a block diagram illustrating a control configuration of the image forming apparatus according to the first embodiment of the present invention. FIG. 7 is a flowchart illustrating an operation of the image forming apparatus according to the first embodiment of the present invention. FIG. 8 is a flowchart illustrating an operation of adjusting a correction coefficient of an LUT. FIG. 9 is a flowchart illustrating an example of image processing in an image processing control unit of the image forming apparatus. FIG. 10 is a flowchart illustrating a transfer path of a transfer material according to the first embodiment of the present invention. FIG. 11 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment of the present invention. FIG. 12 is a schematic diagram of an image forming apparatus according to third and fourth embodiments of the present invention. FIG. 13 is a flowchart illustrating an operation of the image forming apparatus according to the third embodiment of the present invention. FIG. 14 is a flowchart illustrating a transfer path of a transfer material according to a third embodiment of the present invention. FIG. 15 is a flowchart illustrating an operation of the image forming apparatus according to the fourth embodiment of the present invention. FIG. 16 is a flowchart showing a transfer path of a transfer material according to a fourth embodiment of the present invention. [Description of Signs] A Image forming means M Drive motor P Station (image forming section) T1 Primary transfer section (transfer position) T2 Secondary transfer section (transfer position) 12 Intermediate transfer member (image carrier) 13 Secondary transfer roller (Transfer unit) 14 Fixing unit (fixing unit) 15 Fixing roller 16 Double-sided flapper (conveying direction switching unit) 17 Switchback mechanism unit (reversing mechanism unit) 18 Double-sided unit (double-sided conveying unit) 19 Paper discharging unit (discharging unit) 20a First switchback flapper (transport direction switching means) 20b Second switchback flapper (transport direction switching means) 22 Transfer material (recording medium) 23 Photosensitive drum (electrophotographic photosensitive member, image carrier) 29 Pressure roller 40 Density control optical sensor 44 Toner density patch pattern 50 Color sensor (detection means) 51 White LED 52 RG Charge accumulation sensor with B-on-chip filter 60 Toner patch pattern (pattern of reference toner image) 61 Single-color gray gradation patch 62 Process gray gradation patch 100 Image forming apparatus 101 Image processing control unit (Image processing unit) 102 LUT 103 Image Formation control unit (control means)

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masaji Uchiyama             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non Corporation (72) Inventor Yoichiro Maebashi             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non Corporation F term (reference) 2H027 DA09 DE02 DE07 DE10 EA02                       EA05 EB04 EC03 EC06 EE05                 2H028 BA06 BA09 BA16                 2H072 AA32 AB14 CB01 CB06 JA04                 3F053 BA03 BA12 LA03 LB03                 3F100 AA01 CA12 CA15 EA03

Claims (1)

1. An image forming means for forming a toner image on an image carrier, a transfer means for transferring the toner image formed by the image forming means to a transfer material at a transfer position, and Fixing means for fixing the toner image transferred by the transfer means on the transfer material; reversing means for reversing the transfer material on which the toner image is fixed by the fixing means; and transferring the transfer material reversed by the reversing means to the transfer material. Double-sided conveying means for conveying to a transfer position, detecting means for detecting the density or chromaticity of the toner image fixed on the transfer material by the fixing means at a predetermined detection position, wherein the predetermined detection position, A detection unit that is a predetermined position on a conveyance path from the time when the transfer material passes through the double-sided conveyance unit to the transfer position; and a control unit that controls the image forming unit based on a detection result of the detection unit. That a control means for an image forming apparatus according to claim.