JP4285733B2 - Double-sided image forming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a double-sided image forming apparatus that can adjust the image density on both sides of a transfer sheet.In placeRelated.
[0002]
[Prior art]
Conventionally, as a double-sided image forming apparatus for forming images on both sides of a recording sheet, there is a double-sided printer apparatus as described below. In this double-sided printer, a photosensitive drum, which is a first image carrier, is disposed in the approximate center of the apparatus, and a cleaning device, a charge eliminating device, a charging device, and a developing device are disposed around the photosensitive drum. Further, an exposure device is disposed above the photosensitive drum, and the photosensitive drum is irradiated with laser light emitted from the exposure device.
[0003]
An intermediate transfer belt (endless belt) as a second image carrier is provided below the photosensitive drum, and a part of the photosensitive drum is provided in contact with the intermediate transfer belt. The intermediate belt is stretched and supported by a plurality of rollers. Inside the loop of the intermediate transfer belt, a backing roller, a cooling unit, a fixing roller, a first transfer unit, and the like are disposed.
[0004]
The fixing roller fixes the toner image transferred to the first surface of the recording paper on the recording paper. The first transfer means is provided at a position facing the photosensitive drum across the belt, and transfers a toner image formed on the photosensitive drum to an intermediate transfer belt or a recording sheet (first surface).
[0005]
A second transfer unit, a fixing device, and a belt cleaning device are arranged on the outer peripheral portion of the intermediate transfer belt. The fixing device includes a fixing roller having a heat source, and fixes the toner image transferred on the second surface of the recording paper to the recording paper. A paper feed cassette is provided below the apparatus main body, and a paper discharge stack is provided above.
[0006]
In the double-sided printer having the above-described configuration, when the apparatus receives a print image signal (write information) from, for example, a personal computer, the exposure device is driven, scanned with laser light, and uniformly charged by the charging device. The body is irradiated, and a latent image corresponding to the written information is formed on the photoreceptor.
[0007]
The latent image on the photoconductor is developed, and a visible image with toner is formed on the surface of the photoconductor. This toner image is transferred onto the surface of the intermediate transfer belt by the first transfer means on the back side of the intermediate transfer belt as the second image carrier.
[0008]
The intermediate transfer belt rotates in synchronization with the photosensitive drum. When the intermediate transfer belt travels to a predetermined position, a toner image image to be created on another surface (second surface) of the sheet is transferred to the photosensitive member in the above-described process. Forming is started, paper feeding is started from the paper feeding cassette, and is conveyed. The toner image previously transferred to the intermediate transfer belt is rotated once and conveyed toward a position where the belt and the photosensitive drum come into contact with each other.
[0009]
The toner image on the photosensitive member is first transferred by the first transfer unit onto the recording paper (second surface) conveyed to the intermediate transfer belt and the photosensitive drum.
[0010]
While the toner image is transferred from the photoreceptor to the recording paper, the other surface of the paper moves together with the toner image on the surface of the intermediate transfer belt, and when it reaches the second transfer means, it is transferred to the recording paper by the means.
[0011]
The sheet on which the toner images are transferred on both sides of the recording sheet by the first and second transfer units is sent to the fixing area by the running of the intermediate transfer belt, is fixed by the fixing unit, and is discharged to the discharge stack.
[0012]
The double-sided printer apparatus described above is a single-color type printer apparatus, but a full-color image can be formed by adding a revolver type developing apparatus to this apparatus.
[0013]
The revolver type developing device is equipped with four developing units, and the four developing units store toners of each color of yellow (Y), magenta (M), cyan (C), and black (Bk). . In the case of monochrome printing, the developing device having black toner is moved to the developing position to form an image by the above-described operation.
[0014]
In the case of forming a full-color image, writing information to be developed with yellow toner is first written by the exposure device on the surface of the charged photosensitive member in a state where the photosensitive drum and the intermediate transfer belt are separated from each other. The latent image is developed with yellow toner applied by a yellow developer moved to the development position. In the same manner, a magenta image is formed on the surface of the photoreceptor and is overlaid on yellow. Further, a cyan image is formed and superimposed on the previous image on the photoconductor, and finally an image with black toner is superimposed, and a four-color image is formed and carried on the surface of the photoconductor. When creating four color images, the photosensitive drum rotates four times. The subsequent double-sided printing process is the same as the monochrome printing process described above. According to this double-sided printer apparatus, monochrome or color double-sided printing can be easily performed.
(See Patent Document 1).
[0015]
[Patent Document 1]
JP 2002-116679 A (paragraph numbers (0053), (0054), (0056), (0057), (0059), (0060), (0063), (0064), (0066), (0067), (0069), (0070), (0071), (0105), (0106), (0107), FIG. 1, FIG. 4)
[0016]
Although not specified in the above-mentioned patent document, in this type of double-sided printer, in order to control the density of the image printed on the recording paper, the density of the toner image transferred to the intermediate transfer belt is detected and detected. A development voltage or the like is changed in accordance with the output to change the print density of the print image.
[0017]
[Problems to be solved by the invention]
However, when adjusting the density of the printed image in the conventional double-sided printer, the means for detecting the density of the toner image transferred to the intermediate transfer belt detects only the toner image density with respect to the toner image on one side of the recording paper. Not. Therefore, since only the control of matching the toner image density on one side with the toner image density on the other side can be performed, the properties of the image printed on one side (front side) and the other side (back side) of the printing paper. However, there is a complaint that the image-specific density adjustment cannot be performed individually, and a satisfactory printing result cannot be obtained for a user who desires a high-quality printed matter.
[0018]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to (1) make it possible to independently adjust the density of a printed image on one side (front side) and the other side (back side) of a transfer sheet, and (2) It is possible to adjust the density according to the type of print image on one side (front side) and the other side (back side), and (3) to enable high-quality image formation in double-sided image formation. That is.
[0019]
[Means for Solving the Problems]
  The first aspect of the present invention includes a first image carrier, a second image carrier, and a third image carrier that carry a visible image of the original image formed based on the original image. The first image of the original image carried by the image carrier is transferred to the second image carrier, and further transferred to the third image carrier to form the first image of the transfer sheet, and In a double-sided image forming apparatus that forms a second side image of a transfer sheet by transferring a visible image of a second side image of a document carried by one image carrier to a second image carrier. A test pattern for adjusting the density of the first side image of the original and the density of the second side image of the originalBased on the original imageGenerateTest pattern formationMeans and a density of the first surface image formed as a first surface image of the transfer sheet based on the test pattern and transferred to the third image carrier,Detection position is movableA first density detecting means and a density of the second surface image formed as a second surface image of the transfer sheet based on the test pattern and transferred to the second image carrier;Detection position is movableBased on the density detected by the second density detection means, the density detected by the first density detection means and the second density detection means, and the reference density of the first surface and the second surface, respectively, the first surface and the second surface of the transfer sheet, respectively. Density adjusting means for adjusting the density of the original image ofIf the original image is a different type of image on the front and back sides, different test patterns are formed on different tracks of the image carrier, and the test pattern images formed based on the different test patterns are read. The movable first density detecting means and second density detecting means are arranged on the first track and the second track of the image carrier, respectively, so that the original image is the same type of image on the front surface and the back surface. In this case, a test pattern is formed on the third track of the image carrier, the movable first density detecting means and second density detecting means are arranged on the third track, and the original image is displayed. The number of test patterns formed when images of the same type on the front and back are less than the number of test patterns formed when the original image is a different type of image on the front and backThis is a double-sided image forming apparatus.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram of a transfer belt type color duplex printer apparatus which is an example of a duplex image forming apparatus to which the present invention is applied.
First, the configuration and operation of the color duplex printer will be described.
In FIG. 1, the color double-sided printer apparatus has a photosensitive drum 1 serving as a first image carrier at the center of the apparatus, a neutralizing device L, a cleaning device 2, a charging device 3, and a developing device disposed on the outer periphery thereof. An image forming unit a, b, c, d having the device 5 is included. The image forming units a, b, c, and d are provided in four sets with the same configuration for the image forming process of each color of yellow (Y), magenta (M), cyan (C), and black (Bk). These are arranged in the order of Y, M, C, and K with respect to the traveling direction indicated by the arrow of the intermediate transfer belt 10 described later.
[0026]
The photosensitive drum 1 is made of an aluminum cylinder having a diameter of about 30 to 100 mm, and an organic semiconductor layer that is a photoconductive material is provided on the surface thereof. A part of the surface of the photosensitive drum 1 is in contact with an intermediate transfer belt 10 described later.
[0027]
An exposure device 4 is provided below the image forming portions a, b, c, and d, and a laser beam emitted from the exposure device 4 is applied to the photosensitive drum 1 from a writing position between the charging device 3 and the developing device 5. Is done.
[0028]
The exposure device 4 is a photosensitive drum 1 in which a document image read by an image reading unit (not shown) or a document created by a personal computer is uniformly charged by a laser beam scanning device including the optical system of the exposure device 4. Irradiate. Note that an LED array and an imaging device may be used instead of the laser beam scanning device.
[0029]
A first intermediate transfer belt 10 as a second image carrier is supported by rotating rollers 11, 12, and 13 so as to be in contact with the rotating drums 1 of the image forming units a, b, c, and d. It is stretched at 3 points.
[0030]
The first intermediate transfer belt 10 is a resin film or rubber having a substrate thickness of 50 to 600 μm, and has a resistance value that enables a toner image to be transferred from the photosensitive drum 1.
[0031]
On the back side of the first intermediate transfer belt 10 (inside the belt loop), a first transfer means 20 is provided in the vicinity of the rotary drum 1 for each rotary drum 1. Further, a cleaning device 25 for the intermediate transfer belt is disposed outside the loop of the first intermediate transfer belt 10 to scrape off unnecessary residual toner and clean the first intermediate transfer belt 10.
[0032]
Further, the color duplex printer apparatus has a second intermediate transfer belt 100 as a third image carrier on the right side of FIG. The second intermediate transfer belt 100 is made of a resin film or rubber having a substrate thickness of 50 to 600 μm, and has a resistance value that enables a toner image to be transferred from the first intermediate transfer belt 10.
[0033]
The second intermediate transfer belt 100 is supported by rotating rollers 111, 112, and 113 so as to run in the same direction as the moving direction of the first intermediate transfer belt 10, in the figure, counterclockwise, and is stretched at three points by these rotating rollers. Yes. The second intermediate transfer belt 100 is provided with second transfer means 120 on the back side (inside the loop). Further, a charger CH and a cleaning device 250 are provided on the front side (outside the loop).
[0034]
The first intermediate transfer belt 10 and the second intermediate transfer belt 100 are in contact with each other by the rotation roller 11 of the first intermediate transfer belt 10, the rotation roller 113 of the second intermediate transfer belt 100, and the transfer unit 120. A transfer nip is formed.
[0035]
A test pattern reading to be described later is performed at a position facing the front side of the first intermediate transfer belt 10 and before the toner image formed on the first intermediate transfer belt 10 is transferred to the second intermediate transfer belt 100. A pattern sensor PS1 is installed.
[0036]
A pattern for reading a test pattern, which will be described later, is located at a position facing the front side of the second intermediate transfer belt 100 and before the toner image formed on the second intermediate transfer belt 100 is transferred to the recording paper. Install sensor PS2.
[0037]
Below the image forming units a, b, c, and d, paper feeders (paper cassettes) 26a and 26b are installed, and recording paper P is stored in the paper feeders 26a and 26b, respectively. When printing is started, the recording sheet P is conveyed from the uppermost sheet to the registration roller pair 28 through the plurality of sheet feeding guides 29 one by one by the sheet feeding roller 27, and from the registration roller pair 28 to the first intermediate transfer belt. 10 is supplied to a transfer nip between the second intermediate transfer belt 100 and the second intermediate transfer belt 100.
[0038]
Above the image forming apparatus, a fixing device 30 for fixing the toner image of the recording paper on which the toner image is transferred to the recording paper by heating, melting, and guiding the recording paper on which the toner image is fixed to the paper discharge stack 40 A paper discharge guide 31 is provided, and a paper discharge roller pair 32 for conveying the recording paper is provided.
[0039]
A toner storage unit TS for storing supply toner is provided above the image forming units a, b, c, d and below the paper discharge stack 40. Four colors M, C, Y, and B are stored in the form of a cartridge TC.
[0040]
Further, a part 50 of the frame of the color double-sided printer main body can be rotated and opened about the opening / closing support shaft 50A. With this configuration, the conveyance path of the recording sheet is greatly opened, and the jammed recording sheet can be easily taken out.
[0041]
Next, the duplex printing operation of the color duplex printer having the above configuration will be described. A document image to be printed by the color duplex printer is a document image read by a document reading device (not shown) or a document created by a personal computer. When the color double-sided printer device receives these original images, the exposure device 4 of the image forming unit a is driven, and the laser light from the laser light source of the exposure device is scanned by a polygon mirror that is rotated by a motor. And the like, the photosensitive drum 1 that is uniformly charged by the charging device 3 of the image forming section a is irradiated to the photosensitive drum 1 that is the first image carrier of the image forming section a, and the document is applied onto the photosensitive body 1. A latent image corresponding to image writing information is formed.
[0042]
The electrostatic latent image on the photoconductor 1 of the image forming unit a is developed by the developing device 5, and a toner (magenta) image is formed and held on the surface of the photoconductor 1 of the image forming unit a. The toner (magenta) image on the photoreceptor 1 of the image forming unit a is transferred to the image forming units a and b by the first transfer means 20 installed on the back side of the first intermediate transfer belt 10 which is the second image carrier. , c, d are transferred to the surface of the first intermediate transfer belt 10 that runs in synchronization with the photosensitive drums 1.
[0043]
The remaining toner on the surface of the photosensitive drum 1 of the image forming unit a is cleaned by the cleaning device 2 and discharged by the charge removing device L to prepare for the next cycle. The first intermediate transfer belt 10 carries the toner image transferred on its surface and runs counterclockwise as shown in FIG.
[0044]
In the image forming unit b, a toner (cyan) image is formed and held on the surface of the photosensitive drum 1 by the same operation as the image forming unit a. At this time, since the toner (magenta) image previously transferred to the first intermediate transfer belt 10 reaches the image forming portion b as the first intermediate transfer belt travels, the toner (cyan) image becomes the toner (magenta). ) Transferred over the image. In the same manner, the toner (yellow) image and the toner (black) image formed by the image forming portions c and d are further transferred onto the toner image. That is, finally, a visible image (developed image 1) superimposed on the first intermediate transfer belt 10 in four colors is formed and held.
[0045]
Since the second intermediate transfer belt 100 is running in synchronization with the running of the first intermediate transfer belt 10, the visible image 1 transferred to the first intermediate transfer belt 10 is transferred to the first intermediate transfer belt 120 by the second transfer means 120. Transfer is performed from the belt 10 to the second intermediate transfer belt 100.
[0046]
Here, when images are obtained on both sides of the recording paper, the surface of the recording paper on which the image formed first (the visible image 1) is transferred is referred to as the first surface of the paper, and the image formed later (the visible image 2) is transferred. The recording paper surface to be performed is referred to as a second paper surface.
[0047]
Thereafter, when the first intermediate transfer belt 10 travels to a predetermined position, a toner image to be created on the second surface of the recording paper starts to be created by the image forming units a, b, c, d, and the paper is fed. Be started. When the paper feed roller 27 rotates in the direction of the arrow, the recording paper P at the top of the paper feed cassette 26 is pulled out and conveyed to the registration roller pair 28 through the paper feed guide 29.
[0048]
The second intermediate transfer belt 100 runs in synchronism with the first intermediate transfer belt 10, and the visible image 1 transferred to the second intermediate transfer belt 100 rotates around the first intermediate transfer belt 10 and the second intermediate transfer belt 10. The transfer belt 100 is conveyed to a position where it contacts. The visible image 1 of the second intermediate transfer belt 100 is first transferred to the first surface of the recording sheet fed between the first intermediate transfer belt 10 and the second intermediate transfer belt 100 via the registration roller pair 28. Transferred by means 120. At the time of this transfer, the recording paper and the visible image 1 are conveyed at a timing by the registration roller pair 28 so that the positions of the recording paper and the visible image 1 become normal.
[0049]
While the visible image 1 is transferred to the second intermediate transfer belt 100 and makes one turn, the second intermediate transfer belt 100 transfers a toner image (visible) to the first intermediate transfer belt 10 onto the second surface of the recording paper. An image 2) is formed and held and conveyed to the contact surface with the recording paper. The second surface of the recording paper moves together with the visible image 2 of the first intermediate transfer belt 10 (the second surface of the paper is in close contact with the visible image 2 transferred onto the belt 10). When the recording sheet passes through the action area of the charger CH, a voltage is applied to the charger CH, and the visible image 2 of the first intermediate transfer belt 10 is transferred to the second surface of the sheet. Also at this time, the visible image 2 is transported at a timing so that it becomes a normal position.
[0050]
Note that the polarity of the toner when the toner image is formed on the photosensitive drum 1 is negative. By applying a positive charge to the first transfer means 20, the toner image formed on the photosensitive drum 1 is transferred to the first intermediate transfer belt 10, and by applying a positive charge to the second transfer means 120, The toner image formed on the first intermediate transfer belt 10 is transferred to the second intermediate transfer belt 100. Further, the toner image of the first intermediate transfer belt 10 formed thereafter is transferred to the second surface of the recording paper. Further, by applying a positive charge to the charger CH, the negative polarity toner of the second intermediate transfer belt 100 is sucked and transferred to the first surface of the recording paper.
[0051]
The recording paper on which the toner images are transferred on both sides of the recording paper by the action of the second transfer means 120 and the charger CH is sent to the fixing device 30. Here, the toner images (both sides) on the recording paper are fixed at once by the fixing roller. The fixed recording paper is discharged A to the paper discharge stack 40 on the main body frame by the paper discharge roller pair 32 through the guide pair 31.
[0052]
In the case where the paper discharge stack 40 is configured as shown in FIG. 1, the image transferred to the recording paper after the double-sided image, that is, the image directly transferred from the first intermediate belt 10 becomes the lower surface of the paper and is discharged. The paper is discharged to the stack 40. Therefore, in order to align the pages, the image transferred to the second page of the recording paper is first formed and held on the second intermediate transfer belt 100, and the image transferred to the first page is transferred to the first intermediate transfer belt. Transfer directly from 10.
[0053]
By the way, normally, a reverse image (mirror image) is formed on the photosensitive drum 1 and is transferred directly to the recording paper to obtain a normal image. However, when the image transferred to the first intermediate transfer belt 10 is transferred to the paper, When a mirror image is formed on the photosensitive drum 1, it becomes a mirror image at the time of paper transfer. Therefore, in the present embodiment, the image transferred from the first intermediate transfer belt 10 to the recording paper is formed as a normal image on the surface of the photosensitive drum 1 and is transferred from the second intermediate transfer belt 100 to the recording paper. Are exposed so as to form a reverse image on the surface of the photosensitive drum 1. Both the above-described page alignment and forward / reverse image switching exposure can be realized by a known image processing technique.
[0054]
After the toner image is transferred from the second intermediate transfer belt 100 to the recording paper, the cleaning device 250 having a known brush roller, collection roller, blade, and the like inside does not need to remain on the surface of the second intermediate transfer belt 100. Remove toner and paper dust. Although FIG. 1 shows a state in which the cleaning device 250 is separated from the second intermediate transfer belt 100, the cleaning device 250 itself can swing about the support shaft 250A and is in contact with the surface of the second intermediate transfer belt 100. It has a separable structure. Before the transfer to the recording paper, it is released when the second intermediate transfer belt 100 is transporting the toner image, and when cleaning is necessary, it is swung counterclockwise in FIG. The removed toner and paper dust are collected in the toner container 250B and subjected to processing such as disposal.
[0055]
Next, a color double-sided printer apparatus having a function for controlling the density of a double-sided image according to an embodiment of the present invention will be described in detail.
In the color double-sided printer apparatus of FIG. 1 again, the test pattern sensors PS1 and PS2 are used to control the density of the image transferred to the first and second sides of the paper, and to control the second intermediate transfer belt 10 and the third intermediate transfer. The density of the test pattern toner image formed on the belt 100 is detected. For this purpose, the test pattern sensors PS1 and PS2 are configured to irradiate the toner image of the test pattern formed on the belt surface with light and receive reflected light, and the first intermediate transfer belt 10 and the second intermediate transfer belt. Installed above 100 belts perpendicular to the belt running direction.
[0056]
The color double-sided printer device includes a control device (not shown) for controlling the density of the double-sided image, and this control device has a CPU, a RAM, a ROM, an HHD device, and the like. Then, the CPU reads a test pattern from the HDD device according to a procedure described in a predetermined program, writes it on the image reading screen, and forms a latent image of the test pattern on the photosensitive drum 1 by exposure. From this latent image, a test pattern toner image is formed on the first intermediate transfer belt 10 and the second intermediate transfer belt 100 by the same method as the above-described image forming method.
[0057]
FIG. 2 is a diagram showing a test pattern toner image formed on the surface of the intermediate transfer belt. In FIG. 2, a, b, c, and d are toner images (visualized image 1) formed on the second intermediate transfer belt 100. E, f, g, and h are toner images (visualized image 2) formed on the first intermediate transfer belt 10. The test pattern is generated as a square pattern on the photosensitive drum 1, the first intermediate transfer belt 10, and the second intermediate transfer belt 100 so as to be relatively on the same track C1 by a test pattern generation unit (not shown). Is done. The test pattern sensors PS1 and PS2 for detecting the density of the toner image of these test patterns are from the upper direction perpendicular to the traveling direction of the toner image indicated by an arrow in the drawing, that is, the traveling direction of the first and second intermediate transfer belts 10 and 100. It is installed so that light is irradiated toward the surface of the intermediate transfer belt and the reflected light is received. Therefore, when the toner image passes through a density detection position that is a light irradiation and reflection point (black circle in FIG. 2), the density is detected. By generating the test pattern on the same track, the test pattern can be made the same.
[0058]
  FIG. 3 is a view showing a toner image of another test pattern formed on the surface of the intermediate transfer belt. In FIG. 3, p, q, r, and s are toner images formed on the second intermediate transfer belt 100 ( A visible image 1), and t, u, v, and w are toner images (developed image 2) formed on the first intermediate transfer belt 10. At this time, the test pattern is generated by separately dividing the track C2 of the toner images p, q, r, and s and the track C3 of the toner images t, u, v, and w. For this reason, the test pattern sensors PS1 and PS2 can move their detection positions substantially across the running line, and the different track C2, C3Install in correspondence with the above.
[0059]
The CPU controls the exposure light amount adjustment voltage, the charging voltage or current, the development voltage, the transfer voltage, or the current based on the detection outputs of the test pattern sensors PS1 and PS2, and the toner of the image transferred to the first and second surfaces of the sheet. Control the image density.
[0060]
Therefore, when the exposure light amount adjustment voltage, charging voltage or current, development voltage, transfer voltage or current are set so that the best printed image can be obtained, the test pattern toner image runs under the test pattern sensors PS1 and PS2. Each toner image density is detected, the density value for each test pattern is plotted, and the relationship is stored in the RAM as the toner image density characteristic S0.
[0061]
FIG. 4 is a toner image density characteristic diagram schematically showing the relationship between the test pattern and the toner image density. In the figure, S0 is a test when the exposure light amount adjustment voltage is set to a value that gives the best printing result. The relationship between the pattern and the toner image density is shown, and S1 and S2 show the relationship between the test pattern and the toner image density at the test before the actual printing operation.
[0062]
Therefore, before adjusting the toner image density of the image that is actually transferred to the first and second sides of the sheet, the user gives an instruction to adjust the print density from the operation panel (not shown) together with a print instruction from the color duplex printer. . Then, the control unit of the color double-sided printer reads the test pattern stored from the HDD device, forms a latent image of the test pattern on the photosensitive drum 1, and applies it to the second intermediate transfer belt 100 shown in FIGS. A test pattern toner image (developed image 1) is formed on the first intermediate transfer belt 10 and a test pattern toner image (developed image 2) is formed.
[0063]
The test pattern sensors PS1 and PS2 detect the density of the toner images (the visible image 1 and the visible image 2) of the test pattern, and the detection output is transmitted to the control unit to generate toner image density characteristics S1 and S2. The CPU of the control unit compares with the characteristic S0 stored as the best characteristic, and when there is a difference, the exposure device and / or the charging device and / or the charging device Control the amount of process such as voltage or current of the developing device and / or the transfer device, and obtain the process setting value. The process setting values are stored, and when actual image formation is performed, the process setting values are used.
[0064]
FIG. 5 is a flowchart showing a procedure for adjusting the process setting value for controlling the density of the toner image. The adjustment procedure will be described with reference to the flowchart. First, the color double-sided printer is turned on, and the user instructs “adjustment of printing density”. Then, the control unit starts the process setting value adjustment process, and the CPU reads the test pattern for the toner image (developed image 2) for the second side of the sheet from the HDD device, and performs the first intermediate process by the image forming process described above. A test pattern toner image (visible image 2) is formed on the surface of the transfer belt 10 (S1). When the toner image passes through the test pattern sensor PS1, the density of the toner image is detected by the sensor PS1 (S2). The detected toner image density is returned to the control unit and compared with the optimum toner image density for performing the best image formation that has been set, and the process set value for the visible image 2 is adjusted so that the difference is eliminated (S3). ). The adjusted process setting value is stored in the RAM (S4). Subsequently, the CPU reads a test pattern for the toner image (visible image 1) for the first surface of the paper from the HDD device, and the toner image (visible image) of the test pattern is formed on the surface of the second intermediate transfer belt 100 by the image forming process described above. Image 1) is formed (S5). When the toner image passes through the test pattern sensor PS2, the density of the toner image is detected by the sensor PS2 (S6). The detected toner image density is returned to the control unit, compared with the set optimum toner image density, and the process setting value for the visible image 1 is adjusted so as to eliminate the difference (S7). The adjusted process setting value is stored in the RAM (S8). Then, this setting process ends. Thereafter, the process setting values stored in the RAM are used for the actual color double-sided image formation.
[0065]
In the present embodiment, the control of the toner image density in the color double-sided printer device using the intermediate transfer belt method has been described. However, the present invention is similarly applied to the color double-sided printer device having the revolver type developing device and the monochrome double-sided printer device. Can do. In the present embodiment, the adjustment of the print density is described as being performed before the printing operation, but may be performed by interrupting the printing operation. At this time, the shape of the test pattern is considered so that the adjustment is performed in a short time.
[0066]
According to the present embodiment, the printing paper is based on the density of the toner image (developed image 1) formed on the second intermediate transfer belt 100 and the toner image (developed image 2) formed on the first intermediate transfer belt 10. The density of the printed image can be adjusted independently for one surface (front surface) and the other surface (back surface). At this time, since the image formation is performed with the process setting value that brings the toner image density characteristics S1 and S2 close to S0, the image formation with the same density is performed on one surface (front surface) and the other surface (back surface) of the printing paper. Can do. If a characteristic S0 is prepared for one side (front side) and the other side (back side) of the printing paper, image formation can be performed with a density specific to each side. In addition, the same test pattern can be used for one side (front side) and the other side (back side) of the printing paper when both sides are the same type of image formation, such as character image formation. The formation of the test pattern of the visible image 1 can be omitted, and when different images are formed, such as a pattern image on the front side and a character image on the back side, different test patterns can be used. Therefore, it is possible to easily adjust the density according to the above, and to obtain a high-quality print result.
[0067]
As described above, the double-sided image forming apparatus and the double-sided image forming method according to the embodiments of the present invention have been described. However, in order for the computer of the double-sided image forming apparatus to function as a unit for executing double-sided image formation, It is described as a computer program in a program language, and this program is recorded on a recording medium such as a flexible disk, CD-ROM, DVD-ROM, MO, etc., and this is read by a computer of a double-sided image forming apparatus. Such double-sided image formation processing can be easily performed. In addition to recording the program on a recording medium, the program can be directly read by the computer of the double-sided image forming apparatus via an arbitrary network such as the Internet or an intranet.
[0068]
【The invention's effect】
  According to the present invention,The image density can be adjusted independently on the first surface (front surface) and the second surface (back surface) of the transfer sheet. Therefore, a high-quality image can be formed on each of the first surface (front surface) and the second surface of the transfer sheet.
  originalIt is easy to adjust the density depending on the type of the draft image, for example, when the first and second sides of the document are different from each other, such as a monochrome image, or the first side of the document is a monochrome image and the second side is a color image. A test image can be selected and generated.
  TeWhen the position of the strike image is generated on the same track, the case where it is generated on a different track can be handled..
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a belt-type color duplex printer that is an example of a duplex image forming apparatus to which the present invention is applied.
FIG. 2 is a view showing a toner image of a test pattern formed on the surface of an intermediate transfer belt.
FIG. 3 is a view showing a toner image of another test pattern formed on the surface of the intermediate transfer belt.
FIG. 4 is a diagram illustrating a relationship between a test pattern and a toner image density.
FIG. 5 is a flowchart showing a procedure for adjusting a process setting value for controlling the density of a toner image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Cleaning device, 3 ... Charging device, 4 ... Exposure device, 5 ... Developing device, 10 ... Intermediate transfer belt, 11 ... Rotating roller , 20 ... first transfer means, 25 ... cleaning device, 26 ... paper feed device, 27 ... paper feed roller, 28 ... registration roller pair, 29 ... transport guide, 30 ..Heating device, 100 ... intermediate transfer belt, 111 ... rotary roller, 120 ... second transfer means, 250 ... cleaning device

Claims (1)

The first image carrier has a first image carrier, a second image carrier, and a third image carrier that carry a visible image of the original image formed based on the original image. A visible image of the first side image of the original is transferred to the second image carrier, and further transferred to the third image carrier to form the first side image of the transfer sheet, and the first image carrier carries A double-sided image forming apparatus for forming a second side image of a transfer sheet by transferring a visible image of a second side image of a document to a second image carrier;
Test pattern forming means for generating , based on the document image, a test pattern for adjusting the density of the first surface image of the document formed on the transfer sheet and the density of the second surface image of the document ;
It is formed as the first screen image of the transfer sheet based on the test pattern, detecting the density of the third of the first screen image that has been transferred to the image bearing member, a first density detecting means which detects the position can be moved ,
A second density detecting means for detecting the density of the second surface image formed as a second surface image of the transfer sheet based on the test pattern and transferred to the second image carrier, the detection position being movable ; ,
Based on the densities detected by the first and second density detectors and the reference densities on the first and second surfaces, the density of the original image on each of the first and second surfaces of the transfer sheet is adjusted. Density adjustment means,
If the original image is a different type of image on the front and back sides, different test patterns are formed on different tracks of the image carrier, and the test pattern images formed based on the different test patterns are read. The movable first density detection means and second density detection means are respectively disposed on the first track and the second track of the image carrier,
When the original image is the same type of image on the front and back sides, a test pattern is formed on the third track of the image carrier, and the movable first density detection means and second density detection means are provided as the first density detection means. Placed on track 3,
The number of test patterns formed when the original image is the same type of image on the front and back sides should be less than the number of test patterns formed when the original image is a different type of image on the front and back sides.
A double-sided image forming apparatus.

Images