JPH063886A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the vibration of a carry belt and to achieve highly accurate control of an image forming means, in an image forming device provided with a device which reads a test pattern on the carry belt. CONSTITUTION:A carry-belt support member 51 is provided on the back of the carry belt 6 and the support member 51 is provided with a vertical through openings 54, and the lower part of the member 51 is covered with a technical box 52 having an exhaust fan 53. When a test patch is generated and the exhaust fan 53 is energized, the carry belt 6 adheres to the support member 51 and does not vibrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer which utilizes electrophotography.

[0002]

Problems and Solutions to be Solved by the Related Art and Invention

"Conventional Example 1" FIGS. 4 and 5 show a conventional color image forming apparatus. In the figure, image forming units PM, PC, PY, which form images of magenta, cyan, yellow, and black, respectively.
PKs are arranged along the transfer material conveying device 60. Each of the image forming units PM, PC, PY, and PK has the same configuration, and the constituent members thereof are each provided with a numerical symbol and then any one of MCYK at the end of the symbols representing the image forming units.
FIG. 5 shows the image forming section PK. Therefore, in the description common to each image forming unit, the same symbols as the symbols at the end of the image forming units are omitted.

Around the photosensitive drum 1 rotating in the direction of the arrow in the figure, a primary charger 2 for uniformly charging the surface of the photosensitive drum 1, a laser light source, a collimator lens, a scanning optical device 3 including a polygon mirror, and a photosensitive drum. A surface potential detector 11 for detecting the potential of the surface of the drum 1, a developing device 4 for converting a latent image on the photosensitive drum 1 into a visible image, and a transfer material conveying device 6
A transfer charger 7 for applying a charge for transferring the visible image to the transfer material sent from the right side to the left side of the drawing with 0, a cleaning device 5 for cleaning the residual toner on the photosensitive drum 1 after the transfer, and the like are arranged. Has been done. The transfer material transport device 60 includes a drive pulley 6
A conveyor belt 6 is stretched between a and the driven pulley 6b as a transfer material carrying sheet of a dielectric endless belt.

As shown in FIG. 5, the surface potential detector 11 is connected to the controller 100 via a surface potential meter 14. A test pattern reading device 12 for reading a test pattern 22 such as a registration mark or a test patch provided on the conveyor belt 6 is provided. The reading device 12 includes a reading sensor 12a, such as a CCD, and an imaging lens 12c that reflects the test pattern 22.
An illumination lamp 1 for illuminating the image light of the test pattern to the CCD via the test pattern 22 from a direction perpendicular to the test pattern 22.
It consists of 2b. The test pattern read by the reading sensor 12a is converted into a density signal via the density conversion circuit 16 and input to the controller 100.

The controller 100 manages each of the above detection information and controls each image forming condition. Next, the order of image formation will be described. Primary charger 2 uniformly on photosensitive drum 1
Is charged by. Next, a light image is exposed by the scanning optical device 3, and this light image is based on a signal which is scanned and read by a scanner (not shown) for reading a document and image-processed. By exposing this light image, the photosensitive drum 1
A potential latent image is formed on. This latent image is subsequently developed with toner by the developing device 4 and becomes a visible image. Thereafter, this toner image is transferred by the transfer charger 7 onto a transfer material which is carried by the conveyor belt 6 and moves in the direction of the arrow in the figure. A full-color image in which the above steps are repeated at the magenta, cyan, yellow, and black stations PM, PC, PY, and PK is obtained. On the other hand, from the controller 100,
The output of the test pattern is instructed at predetermined intervals, and the same image as the test pattern is printed on the photosensitive drum 1 in the same manner as the above process.
The transfer belt 6 formed on the transfer belt 6 without the transfer material being transferred.
The test pattern is read on the conveyor belt 6 by the test pattern reading device 12 to detect the density. The detected toner concentration is arithmetically processed by the controller 100, and image forming means, for example, a charging potential,
The LUT, toner density, transfer current, etc. are controlled. In addition, the stability of registration is also improved by using a method of detecting a color shift of each color by detecting a registration mark and correcting an optical system with an actuator.

[Problem 1 to be Solved by the Invention] However, in the above-mentioned conventional example 1, the conveyor belt may vibrate up and down during movement, and when the conveyor belt vibrates up and down, the focus shift of the test pattern reading device may occur. As a result, the absolute density value becomes unstable during the density conversion calculation in the density conversion circuit, making it impossible to control the image forming means with high accuracy.

"Means for Solving Problem 1" The problems to be solved by the above invention are solved by the following means.

The first aspect of the present invention is to read a plurality of test patterns for registration correction or image forming means correction on the transfer material conveying belt with a reading device to form a plurality of images for forming a desired image. An image forming apparatus having means for performing multiple recording on a transfer material using a forming means and means for detecting the density of the test pattern on the transfer belt, wherein the transfer material transfer device is provided near a position where the test pattern is read. The image forming apparatus is characterized by having a conveyor belt supporting means for stably supporting the conveyor belt.

A second invention of the present invention is the first invention, characterized in that the conveyor belt supporting means has a conveyor belt supporting member which is in contact with the conveyor belt, a conveyor belt and a suction means for adsorbing the conveyor belt supporting member. The image forming apparatus described above.

A third aspect of the present invention is the image forming apparatus according to the first aspect, wherein the conveyor belt supporting means has an upper supporting member provided on the upper and lower portions of the conveying belt and a lower supporting member. is there.

A fourth aspect of the present invention is characterized in that both upper and lower support members can be brought into and out of contact with the conveyor belt.
The image forming apparatus according to the invention.

In a fifth aspect of the present invention, the image forming apparatus according to the fourth aspect is characterized in that both upper and lower support members are contacted with and removed from the conveyor belt according to the presence or absence of the formation of a test pattern. is there.

"Conventional Example 2" The test pattern reading device 12 described with reference to FIG. 4 illuminates the test pattern written on the conveyor belt from a direction perpendicular to the direction in which the conveyor belt moves and forms an image of reflected light of the test pattern. A lens is used to form an image on a solid-state image sensor such as a CCD for reading.

[Problem 2 to be Solved by the Invention] However, in the above-mentioned conventional example 2, the transfer material conveying device cleans the drive pulley and the conveying belt for moving the conveying device when the driving time of the image forming apparatus becomes long. A streak-like scratch is generated in the carrying direction by a cleaning device for cleaning. In particular, when the transport belt is a transparent belt, scratches occur on both the front surface and the back surface of the belt. A test pattern is written on the conveyor belt having the streak-like scratches, and the test pattern 2 is formed by the illumination lamp 12b at a right angle to the conveying direction a as shown in FIGS.
When illuminating 2 to read, the reflected and scattered light from the scratches on the conveyor belt 6 is incident on the reading sensor 12a of the solid-state imaging device such as CCD, so that the reading sensor by reflection on the conveyor belt 6 as shown in FIG. The output 6A of 12a becomes high, and the output 22A of the reading sensor 12a based on the reflection of the test pattern 22 to be read is based on the reflection of the conveyor belt 6 from the reading sensor 1
There is a drawback that the output 6A of 2a is lost and cannot be read.

"Means for Solving Problem 2" The above problem 2 is solved by the following means.

A sixth aspect of the present invention is an image forming means for forming a target image by reading a test pattern for registration correction on the transfer material conveying belt or for correcting image forming means with a reading device. In an image forming apparatus having means for transferring onto a transfer material using a transfer material and means for detecting the density of the test pattern on the transfer belt, the test pattern reading device illuminates the test pattern on the transfer material transfer belt. Lighting equipment,
A reading sensor for reading the test pattern image by projecting the reflected light of the test pattern illuminated by the illuminating device by the imaging lens, and the illuminating device is a surface projected onto the transfer material conveying belt in the moving direction of the transfer material conveying belt. The image forming apparatus is characterized in that the inside angle is within 60 degrees.

"Conventional Example 3" As described with reference to FIG. 4, the transfer belt for transferring the transfer material is wound around a pulley such as a drive pulley and linearly conveyed in parallel along each photosensitive drum. However, due to mechanical vibrations due to the tension and load of the conveyor belt, environmental conditions, etc., the conveying condition of the conveyor belt may fluctuate, and the conveyor belt may be conveyed while leaning in one direction. The deviation of the conveyance belt and the deviation of the conveyance belt are controlled so that, for example, the end of the conveyance belt is monitored by a sensor and a load is applied to the conveyance belt so that the conveyance belt deviates in the opposite direction. Therefore, the conveyor belt advances while being controlled to swing in the left-right direction.

[Problem 3 to be Solved by the Invention] However, in the swing control of the conveyor belt of the conventional example 3, since the condition of the conveyor belt is simply detected, the end of the conveyor belt is simply detected. For example, even if a sensor detects the end of the conveyor belt and a load is applied so that the deviation of the conveyor belt moves in the direction opposite to that detected at the end of the conveyor belt, the conveyor belt end detection sensor detects the end of the conveyor belt. Until it disappeared, it was not possible to determine whether the conveyor belt was moving in the opposite direction from what was detected at the conveyor belt edge.

Further, since the state of the conveyor belt can be known only by detecting the end portion, there is a problem that there is no means for knowing the swing speed of the conveyor belt.

"Means for Solving Problem 3" Problem 3 to be solved by the invention is solved by the following means.

According to a seventh aspect of the present invention, a plurality of image bearing members are arranged side by side, and the images formed on the respective image bearing members are sequentially transferred onto a transfer material which is conveyed by a conveyor belt to form a plurality of color images. In the image forming apparatus capable of forming a mark, the deviation of the conveyance belt is detected by the conveyance belt on which the mark is written and the means for reading the mark.

"Conventional Example 4" As in Conventional Example 3, the transfer material conveying device provided with a conveying belt has the following problems.

[Problem 4 to be Solved by the Invention] In the conventional belt swing control, since a load is simply applied to the conveyor belt in the direction in which the deviation is desired to be returned, a mechanical problem, such as conveyance, may occur. If the degree of deviation in one direction due to the alignment error of the pulleys that support the belt and the degree of deviation when returning the deviation of the conveyor belt by applying a load in the opposite direction, only one side It is fast and easy to lean, and because the speed of the deviation of the conveyor belt cannot be controlled, it delays returning the deviation in the opposite direction, for example, sliding the edge of the conveyor belt against other objects to damage it,
On the contrary, there is a problem that the swinging speed is too fast, which adversely affects the image being transferred.

"Means for Solving Problem 4" Problem 4 to be solved by the invention is solved by the following means.

According to an eighth aspect of the present invention, a plurality of image bearing members are arranged side by side, and the images formed on the respective image bearing members are sequentially transferred onto a transfer material which is conveyed by a conveyor belt to form a plurality of color images. In the image forming apparatus capable of forming a sheet, a means for detecting an offset state of the conveyor belt and a means for correcting the offset of the conveyor belt are provided, and the signal detected by the means for detecting the offset state of the conveyor belt The image forming apparatus is characterized in that a means for correcting the deviation of the conveyor belt is controlled to reduce the deviation amount of the conveyor belt.

"Prior Art Example 5" For example, in a color image forming apparatus having a plurality of image forming units PM, PC, PY, PK shown in FIG. 4, the test pattern reading device 12 uses a microcomputer incorporated in the main body to write start timing and reflection. There is a unit that controls a mirror (not shown) to correct the deviation of each color. Since the toner on which the test pattern 22 is transferred reflects infrared light, the test pattern reading device 12 uses the visible light cut filter 12d as shown in FIG.
The diffused and reflected light of the toner image by the pair of illumination lamps 12b on both sides is read by a reading sensor 12a such as a CCD through a lens 12c.

The CCD output V at that time is as shown in FIG. In FIG. 28, CL is the optical axis of the lens 12c.
The illumination lamp 12b is installed obliquely so that the specularly reflected light from the conveyor belt 6 is not applied to the reading sensor 12a. The conveyor belt 6 is, for example, PET, polyurethane, P
A resin film that transmits transparent or semi-transparent infrared light such as VDF is used. Therefore, the position of the test pattern 22 is detected by the difference between the diffuse reflection light of the test pattern 22 and the reflection light of the conveyor belt 6.

[Problem 5 to be Solved by the Invention] However, in the above-mentioned conventional example 5, when the pulley for holding the conveyor belt 6 is machined, surface crevices, dust adhered to the pulley, and various belts. Backup member (eg Figure 1
When the rear surface of the conveyor belt 6 is damaged by the conveyor belt supporting member 51), the following problems occur. As shown in FIG. 29, in addition to the diffusely reflected light of the test pattern 22, specularly reflected light may jump into the reading sensor 12a due to the scratch 6x on the back surface of the conveyor belt 6, and the output of the reading sensor 12a (CCD) at that time. Is as shown in FIG.
A flaw 6x other than the output V22 corresponding to the test pattern 22
The output V22a due to the reflected light is generated, and the CCD output changes depending on the condition of the scratch 6x, but the microcomputer incorporated in the main body cannot judge the distinction between the scratch 6x and the test pattern 22, so the control is performed by reading the scratch 6x. Then, the color shift becomes more intense.

Further, in this structure, since only the transfer material and the photosensitive drum are in contact with the surface of the conveyor belt 6, it is relatively difficult to be damaged, but the damage 6x generated on the surface of the conveyor belt 6 is also the same. It will have an adverse effect.

Basically, in order to read the test pattern 22, erroneous reading is prevented as the difference between the reflected light of the toner due to the light of the illumination lamp 12b and the reflected light of the conveyor belt 6 increases. Since the color toner that is currently generally used is a type that reflects infrared light, it is desirable to make the reflected light of the conveyor belt 6 to be zero. Therefore, in the conventional conveyor belt 6, a transparent or semitransparent resin is used. The reflectance was lowered by increasing the transmittance with respect to the light of the illumination lamp 12b using a film. However, in the case of the resin film made of such a material, when the scratches 6x are generated due to the above-mentioned causes, the appearance of whitish scratches is likely to occur. In other words, the damaged portion means that the light transmittance decreases, and the reflected light increases accordingly. This also applies to infrared light, and there is a drawback in that scratches on the conveyor belt 6 tend to increase the reflectance instead of lowering the transmittance.

Therefore, considering that the transport belt 6 having the increased transmittance as described above smoothly rotates as a transport belt, it is difficult to increase the hardness of the material to prevent scratches, which makes it difficult to select the material. It has a drawback that the life of the conveyor belt 6 is significantly reduced only to prevent erroneous reading.

"Means for Solving Problem 5" Problem 5 to be solved by the invention is solved by the following means.

A ninth aspect of the present invention is a plurality of image forming means for forming a desired image by reading a test pattern for registration correction on the conveyor belt or for correcting image forming means with a reading device. An image forming apparatus having a means for transferring onto a transfer material by using a carrier belt having an absorptance for infrared light higher than a transmissivity.

The tenth invention of the present invention is the image forming apparatus according to the ninth invention, wherein the conveyor belt is made of a resin in which carbon is kneaded.

"Conventional Example 6" FIG. 48 is a sectional view showing another example of the image forming apparatus of this type. It is composed of a pixel reading unit that color-separates a color original for each pixel and digitally reads it as an electric signal, and a laser beam printer unit (LBP) that obtains a full color print by an electrophotographic method using an image signal converted into an electric signal.

The configuration and operation will be described below.
It should be noted that part of the description overlapping with FIG. 4 is omitted.

In the image reading section, the color original 31 is illuminated by the original exposure lamp (illumination lamp) 32, and the color reflected light image reflected from the color original 31 is formed on the color image sensor 33. The color image signal separated by the color image sensor 33 (CCD color line sensor) for each pixel is processed by the color signal processing circuit 35.
The signal is processed and input to the image processing circuit 26.

In the image processing circuit 26, after the input signal is digitized and the color signal is color-corrected by digital image processing, the digital image signal is converted into image forming units PM, PC, P.
Send to Y, PK.

The image forming section has an image forming section for carrying out a latent image step and a developing step for each color of magenta (M), cyan (C), yellow (Y) and black (BK). The images visualized in step 1 are transferred to a recording medium in multiple transfer.

In this system, since the electrophotographic processes can be overlapped with each other, the copying speed can be increased, which is called the 4D system.

The optical scanning device 3 is a laser unit 36M, 36 including a laser light source, a tilt correction lens, and an fθ lens.
The signals modulated from C, 36Y, and 36K are rotating polygon mirror 3
7 is sent to the reflection mirror 45M for magenta,
The light is reflected by 46M and 47M and forms an image on the photosensitive drum 1M.
The same applies to other colors.

The transfer unit includes a transfer belt 6 for holding and transferring the transfer material of the recording medium, and transfer chargers 7M, 7C, 7
It consists of Y and 7K.

The image forming units PM, PC, PY,
The image formed by PK is transferred to the transfer chargers 7M, 7C, 7
Multiple transfer is performed on the transfer material with Y and 7K.

As the transfer material fed from the paper feed cassette 61 progresses, the tip of the transfer material reaches the ITOP sensor 67.
When it is detected by, the image signal of each color component already stored in the memory device is read at an appropriate timing by a timing control circuit (not shown) in synchronization with the leading edge signal of the transfer material, and the laser exposure of the image forming unit is performed. Input to the device.

In such an apparatus, since images of magenta, cyan, yellow, and black color components are formed for each image forming portion, it is an important technique how to accurately superimpose the images of the image forming portions. In a high-quality full-color copying machine, the positional accuracy of superimposing images of respective color components needs to be 100 μm or less. If the amount of image shift becomes larger than this, color shift due to color overlapping,
Color unevenness occurs. It is very difficult to adjust each component for image formation with such accuracy. Even if adjustments can be made, for example, misalignment due to thermal expansion of each component due to temperature fluctuations, misalignment due to reproducibility of mechanical position accuracy after jam processing, scratches on photosensitive drums, and defects in developing devices. The adjusted position is immediately displaced due to the replacement of parts due to such reasons, and once it is displaced, it is virtually impossible for the user to adjust it.

Therefore, in order to make such adjustment automatically,
For example, as shown in FIG. 49, a test pattern 22 for registering each color component of yellow, magenta, and cyan is printed on the conveyor belt 6 at a constant interval, and the test pattern 22 is composed of, for example, a CCD at two places, a back side and a front side. By reading with the reading devices 12-1 and 12-2, the deviation amount in the main scanning direction and the sub scanning direction in each image forming unit, the inclination, etc. are detected, and the deviation amount in the sub scanning direction and the main scanning direction is detected by the correction unit. A device that automatically corrects is proposed.

Automatic Correction in Sub-scanning Direction FIG. 50 is a timing chart showing the timing of forming registration marks in this type of image forming apparatus.

As shown in FIG. 50, the sub-scanning direction is
The counter circuit (not shown) counts the number of lines from the rising edge of the output signal ITOP from the ITOP sensor 67 that detects the leading edge of the transfer material. For example, magenta counts tm hours, cyan counts tc hours, and yellow counts. After the ty time has been counted out, in the case of black, the tk time is counted, and then the output signals MTOP, CTOP, YTOP, and KTOP signals are respectively transmitted, whereby the above-described test pattern 22 is detected by the reading devices 12-1 and 12-2. The counts tm, tc, ty, kk may be determined based on the timing.

Automatic Correction in the Main Scanning Direction FIG. 51 is a timing chart showing test pattern formation timing in this type of image forming apparatus.

Each signal MBD, CBD, YBD, KBD is a detection signal of a laser beam for forming a latent image of magenta, cyan, yellow and black, and each signal determines the main scanning position of the image at each position. It is a reference signal for performing. Each image has a laser beam detection signal MBD,
Image count x from CBD, YBD, KBD
It is generated after m, xc, xy, xk, and is determined by the enable signals MEN, CEN, YEN, KEN, so that this is also based on the positions detected by the reading devices 12-1 and 12-2 described above. The value should be set appropriately.

The automatic tilt correction is performed, for example, for magenta by tilting the reflecting mirrors 45M, 46M and 47M by an actuator (not shown).

[Problem 6 to be Solved by the Invention] By reading the test pattern 22 thus transferred to the conveyor belt by the reading sensor 12a such as a CCD, it is possible to detect the deviation of the registration.
Since the CD sensor detects the reflected light from the toner pattern on the conveyor belt,
It was necessary to have a reflection area (sensitivity) with respect to irradiation light. This condition is satisfied for magenta, cyan, and yellow toners. However, in the black toner, magenta, cyan, and
When using a mixture of an appropriate amount of yellow colorant,
Although there is no problem, black produced by mixing three kinds of colorants has a complicated manufacturing method, which makes it difficult to control the tint and increases the manufacturing cost. Therefore, if a carbon-based colorant used in a black-and-white copying machine is used as a normal colorant, there is no reflection area in any wavelength range, and the pattern on the conveyor belt cannot be identified.

52, 53, and 54, magenta, cyan,
The reflectance of the yellow and black toners with respect to the irradiation light wavelength, that is, the spectral reflectance characteristic is shown.

That is, yellow (Y) shown in FIG.
The toners of magenta (M) and cyan (C) are 400 to 500 nm, 500 to 600 nm, and 600 to 600 nm, respectively.
Since it absorbs light having a wavelength of 700 nm, conversely, it has a reflection region at other wavelengths. Further, black BK shown in FIG. 53, which is a mixture of these three kinds of colorants, has a reflection region in the infrared region. In a system using such a toner, the mark may be read by diffused reflection of infrared light from the surface of the toner particles.

However, when carbon is used as the colorant for black BK as shown in FIG. 54, there is no reflection in all wavelength regions.

As a result, there is a problem that the registration deviation of the black image forming portion PK cannot be detected.

The present invention has been made in order to solve the above problems, and a resist correction test pattern with toner of a color that cannot detect reflected light due to its spectral characteristics can be detected on the conveyor belt in terms of its spectral characteristics. An object of the present invention is to obtain an image recording apparatus that detects registration deviation by transferring the toner onto a resist correction test pattern in an overlapping manner and reading the overlapping amount with a sensor.

"Means for Solving Problem 6" Problem 6 to be solved by the above invention is solved by the following means.

An eleventh aspect of the present invention is a plurality of image forming means for forming a target image by reading a test pattern for registration correction on a conveyor belt or for correcting image forming means with a reading device. In an image forming apparatus having means for performing multiple recording on a transfer material by using, and means for detecting the density of the test pattern on the transfer material, the spectral reflectance characteristic of the developer in the image forming portion serving as a reference of the resist is , The test pattern reading device has no sensitivity, and the spectral reflection properties of the developers of other colors have sensitivity, and the test pattern of the reference image forming unit is the test pattern of the image forming unit whose registration is read. Image formation characterized by detecting the amount of resist by overlaying on the test pattern and reading the overlayed test pattern It is the location.

"Conventional Example 7" FIG. 65 shows a conventional image forming apparatus. The photosensitive drum 1, which is an image bearing member, rotates in a clockwise direction toward the drawing. The photosensitive drum 1 is uniformly charged by a charger 2 for uniformly charging the surface. The photosensitive drum 1 is exposed by a scanning optical device 3 including a laser light source, a collimator lens, and a polygon mirror. Photosensitive drum 1
Developing device 4 and photosensitive drum 1 for making the above latent image a visible image
Cleaning device 5 for collecting the toner remaining on the surface of the transfer material, and a transfer material transporting device that transfers the toner image on the photosensitive drum 1 onto the transfer material P while holding the transfer material P by a drum-shaped transfer sheet and transporting the transfer material P. 60 and a transfer charging device 7. Toner concentration sensor 20 for detecting the mixing ratio of the image forming toner and the carrier housed in the developing device 4.
Equipped with. A surface potential detector 11, which is means for detecting the surface state of the photosensitive drum 1, is provided. The reading sensor 12a for reading the test pattern 22 is provided, and the reflected light of the test pattern 22 illuminated by the LED illumination lamp 12b reaches the reading sensor 12a. A density conversion circuit 16 is provided for converting the output voltage obtained by the reading sensor 12a into density. The controller 100 manages each of the above detection information and controls each image condition. Next, the order of image formation will be described. The photosensitive drum 1 is uniformly charged by the charger 2. Next, a light image is exposed on the photosensitive drum 1 by the scanning optical device 3, and this light image is based on a signal obtained by scanning and reading image processing by a scanner for reading a document (not shown). By exposing this light image, a potential latent image is formed on the photosensitive drum 1. This latent image is subsequently developed with toner by the developing device 4 and becomes a visible image. Thereafter, this toner is transferred onto the transfer material P by the transfer charger 7. The above steps are performed by moving and rotating the developing device 4,
Alternatively, in the case of the four-color fixed type, magenta, cyan, and
The four steps of yellow and black are sequentially performed to obtain a full-color image. On the other hand, the controller 100 instructs the test pattern 22 to be output at predetermined intervals, and the test pattern 22 is formed on the photosensitive drum 1 and transferred to the transfer drum 6D in the same manner as the above process. This test pattern is composed of one or a plurality of patterns having a predetermined density. The toner density detected by the reading device 12 is converted into an electric signal by the density conversion circuit 16 and arithmetically processed by the controller 100 to control image forming means such as charging potential, LUT, toner density and transfer current. [Problem 7 to be Solved by the Invention] In the conventional example of FIG. 65, since the photoelectric sensor is used in the pattern reading device, only the reflected light amount of the entire test pattern can be detected, and the microscopic image forming state is detected. It was impossible. In addition, there is a drawback in that the pattern reading device must be arranged at two positions before and after the transfer in order to detect the transfer condition, resulting in a very large-scale device.

"Means for Solving Problem 7" Problem 7 to be solved by the invention is solved by the following means.

The twelfth invention of the present invention conveys a pattern forming means for forming a predetermined test pattern on an image carrier and a pattern on the image carrier or a transfer material formed by the pattern forming means. On the conveyor belt or on the intermediate transfer material carrying member, the reflected light amount detecting means for detecting the reflected light amount of the test pattern in a minute area is provided, and the reflected light amount movement pattern information detected by the reflected light amount detecting means is used. An image characterized by detecting an image forming state of the image forming apparatus, continuously changing the image forming condition and continuously detecting the image forming state, and obtaining an optimum value of the image forming condition based on the detection result. It is a forming device.

A thirteenth invention of the present invention is the image forming apparatus according to the twelfth invention, wherein the means for detecting the image forming condition is a spatial transfer function MTF.

In the fourteenth aspect of the present invention, the image forming condition is a transfer condition which is a transfer current, a contact pressure of a transfer assisting means,
The image forming apparatus according to the twelfth aspect of the invention is characterized in that it is at least one of the peripheral speeds of the photoconductor and the transfer material transport device.

A fifteenth invention of the present invention is the image forming apparatus according to the eleventh invention, wherein the reflected light amount detecting means can read the reflected light amount in a minute area of 30 μm × 30 μm or less.

"Conventional Example 8" Conventionally, various types of color image forming apparatuses have been proposed. One of them is, for example, as shown in FIGS. An image forming unit is provided in each of the image forming units, and in each image forming unit, a visible image for each color is formed on a photosensitive drum as an image carrier by a known image forming process, and sequentially transferred to a transfer material supplied from these visible images, 2. Description of the Related Art There is an electrophotographic color image forming apparatus that collectively fixes a color image. In this case, the transfer material is placed on a conveyor belt that moves in an endless circulation manner and sequentially conveyed to each image forming unit, and the visible images formed on the respective photosensitive drums are sequentially transferred to this transfer material. Also, FIGS.
Although the illustration is omitted for 8, 25, etc., dirt on the conveyor belt,
For example, in order to clean fog toner or paper dust, a rotary cleaning means such as a fur brush is provided to prevent dirt on the back surface of the transfer material. Further, a discharging unit is provided on the downstream side of the image forming unit and on the upstream side of the cleaning unit with respect to the moving direction of the conveying belt, and at the time of cleaning, the electrostatic force of the conveying belt and the residual toner on the conveying belt is neutralized to couple each other. By weakening the toner, cleaning of the residual toner is facilitated.

[Problem 8 to be Solved by the Invention] However, in the above-described conventional example, static electricity is generated by rubbing of the cleaning means and the conveyor belt, so that the conveyor belt is recharged even if static elimination is performed before cleaning. This device uses electrostatic force as a process of adsorbing the transfer material, transferring the image on the photosensitive drum to the transfer material, and separating the image-formed transfer material from the conveyor belt. For the next image formation, the recharging of the conveyor belt by the cleaning means has been a factor causing jamming (paper jam) due to poor transfer material adsorption, poor separation, and abnormal images due to poor transfer in the next image formation.

In addition, since charging due to friction changes remarkably depending on the environment or the like, it has been a big defect as an unstable factor.

As a method for solving the above-mentioned problem, there is a method in which only the charge removal is performed by the charge removal unit before the cleaning unit during the image formation, but since the charge removal unit is provided before the cleaning unit, the cleaning is performed during the image formation. Since it is impossible to operate the cleaning means from the viewpoint of avoiding triboelectrification, the cleaning means must be operated after the image formation is completed. There is a drawback that ends up. Further, when the transfer material cannot be continuously image-formed, the residual toner is not cleaned by the cleaning means after the second round of the conveyor belt, so that the fog toner adheres to the back surface of the adsorbed transfer material. There are drawbacks.

"Means for Solving Problem 8" Problem 7 to be solved by the invention is solved by the following means.

A sixteenth aspect of the present invention is directed to an image forming portion provided with an image carrier on which a visible image is formed, adjacent to the image carrier, and a transfer material is fixed by electrostatic attraction and conveyed. A transfer device having a transfer material transfer belt that passes a position where a visible image is transferred, and a cleaning unit that cleans the transfer belt are provided, and the transfer unit is provided upstream of the image forming unit with respect to the moving direction of the transfer belt. The image forming apparatus is characterized in that a discharging unit is provided downstream.

The seventeenth invention of the present invention is the image forming apparatus according to the sixteenth invention, wherein the cleaning means operates during image formation.

In the eighteenth aspect of the present invention, after completion of image formation,
In the image forming apparatus according to the sixteenth aspect of the invention, the charge removing unit ends the operation after the conveyance belt stops.

The nineteenth invention of the present invention is the image forming apparatus according to the sixteenth invention, wherein the transport device is provided with an endless flexible belt as the transfer material transport belt.

[0075]

Embodiments of the present invention will be described below with reference to the drawings.

The first to third embodiments deal with the problem 1 and solve the problem of the image density detection failure due to the focus deviation of the test pattern reading device due to the vertical vibration of the conveyor belt.

[Embodiment 1] Referring to FIGS. 1 and 2, a member for stably supporting the transfer material carrying sheet according to the present invention will be described. A plate-shaped conveyor belt supporting member 51 is fixed to the back side of the conveyor belt 6 provided as a transfer material supporting sheet at a reading position of the test pattern reading device 12, which is not shown in the drawing, with its plate surface in contact. Since the conveyor belt support member 51 is always in contact with the conveyor belt 6, it is desirable to use a material having a small friction coefficient that does not damage the conveyor belt 6. Further, the conveyor belt support member 51 is surrounded by a suction box 52 having high airtightness, and an exhaust fan 53 for exhausting the space between the member 52 and the conveyor belt 6 is provided on the side of the suction box 52. The conveyor belt support member 51 has an opening 54 that vertically penetrates the member 51, and this portion is in close contact with the conveyor belt 6 so that airtightness can be maintained. With the operation of the exhaust fan 53, the internal pressure of the suction box 52 decreases and the conveyor belt 6 is sucked. In this way, the conveyor belt 6 is sucked and the conveyor belt 6
The vertical movement of the test pattern is eliminated, and these enable stable detection of the density of the test pattern. In this embodiment, the exhaust fan of the adsorbing means for adsorbing the conveyor belt to the conveyor belt support member is provided at the end of the suction box 52. However, the exhaust device and the suction box 52 provided separately in an exhaust duct or the like are provided. It may be connected.

[Embodiment 2] FIG. 3 shows the conveyor belt supporting means. A lower support roller 56 that supports the conveyor belt 6 from below is rotatably supported. The length of the lower support roller 56 should be at least equal to the width of the conveyor belt 6. From the top of the conveyor belt 6 to the conveyor belt 6
Is sandwiched between the lower support roller 56 and an upper support roller 55 rotatably supported at a position facing the lower support roller 56. This upper support roller 55 has 4
Individual pieces are arranged at both ends of the conveyor belt 6 in the width direction. Further, since the upper support roller 55 is provided so as to face the lower support roller 56 at a position outside the paper width of the transfer material, it does not interfere with normal image formation.

[Embodiment 3] In this embodiment, an example in which the above embodiment is further developed is shown. The upper support roller 55 and the lower support roller 56 may be brought into contact with each other only when the test pattern 22 is detected by the reading device 12 to support the conveyor belt 6. For this reason, the bearings that support the upper support roller 55 and the lower support roller 56 are movable in the vertical direction, and the position of the bearing is controlled in the vertical direction by an electromagnetic solenoid or the like so that the upper support roller 55 and the lower support roller 55 are used during normal image formation. 5
Reference numeral 6 is a state in which they are kept apart from each other, an excessive load is not applied to the conveyor belt 6, and the upper support roller 55 and the lower support roller 56 are brought into contact with each other when the test pattern 22 is read. (Shown).

In Examples 2 and 3, the roller-like member 55 is provided as the upper supporting member and the roller-like member 56 is provided as the lower supporting member. However, one or both of them are slidable with the conveyor belt. It is also possible to change to.

In the second and third embodiments, the upper support roller 55 can be arranged at the intermediate portion in the width direction of the conveyor belt except at the position except the test pattern position.

[Example 4] Example 4 corresponds to the problem 2,
The solution is to prevent the reflected light of the illumination light of the reading device of the conveyor belt from entering the reading sensor.

FIG. 6 is a schematic view of an embodiment of the image forming apparatus of the present invention, in which an image is written on the photosensitive drums 1M, 1C, 1Y and 1K by the scanning optical device 3 according to the image information, and the photosensitive drums 1M, 1M, The images written with the rotation of 1C, 1Y, and 1K in the directions of the arrows are recorded in the developing devices 4M,
It is developed by 4C, 4Y and 4K. On the other hand, the transfer material is transferred from the paper feed cassette 61 onto the transfer belt 6 and the images developed and formed on the respective photosensitive drums are transferred onto the transfer material by the transfer chargers 7M, 7C, 7Y and 7K in order from the right.
After they are overlaid, the image is fixed by the fixing device 8 and discharged. While a multiple image is formed by the above process, in order to accurately superimpose the images formed by the photosensitive drums 1M, 1C, 1Y and 1K, each photosensitive drum 1M, A test pattern (for example, # mark) for position detection is written and developed at two positions on the back and front of 1C, 1Y, 1K and transferred onto the conveyor belt 6, and the conveyor belt 6 causes the photosensitive drums 1M, 1C, 1Y, 1
The # mark corresponding to K is the test pattern reading device 1
When moved to the position 2, the # mark is read to detect the misalignment, tilt, magnification, etc. of the writing in the image forming portion corresponding to each photosensitive drum 1M, 1C, 1Y, 1K, and to scan optical The writing timing of the device 3 and the tilt of the mirror are corrected.

As shown in FIGS. 7 and 8, the test patterns (# marks) 22 and 22 formed in the image forming portions corresponding to the photosensitive drums 1M, 1C, 1Y and 1K are the illumination lamps 12b and 12b. The CCD reading sensor 1 illuminates the reflected light with the imaging lenses 12c and 12c.
2a and 12a are image projected and read,
The illumination directions of the illumination lamps 12b and 12b are the same as those in the projection of the plane of the conveyor belt 6 as shown in FIG.
Illumination is performed from within a direction of 60 degrees, for example, a direction of 45 degrees with respect to the moving direction b. By illuminating from this direction, a flaw in the transport direction on the transport belt 6 is illuminated obliquely, and most of the light scattered by the flaw spreads within the cross section illuminated by the illumination lamp 12b. Since the probability of direct incidence on the sensors 12a, 12a is extremely low, the output V6 of the reading device 12 due to the reflected light from the conveyor belt 6 as shown in FIG. −
Only 1 and 22-1 become high, and it becomes easy to detect.

In the fourth embodiment, one illuminating lamp is provided for each test pattern detecting means, but the angle of the illumination direction projected on the conveyor belt is 60 degrees with respect to the moving direction of the conveyor belt. A plurality may be provided as long as it is within the range.

The fifth to sixth embodiments correspond to the above-mentioned problem 3 and control the deviation amount of the conveyor belt.

[Fifth Embodiment] FIG. 17 shows a fifth embodiment of the present invention.
FIG. 4 is a vertical cross-sectional view illustrating the configuration of the image forming apparatus showing
The reader unit 101 includes an image sensor or the like for reading a color image, and a series of image reading sequences is controlled by the reader controller RCON.

The printer unit 102 has a plurality of photosensitive drums (image bearing members) 1M, 1C, 1Y and 1K juxtaposed to each other, and magenta images, cyan images and yellow images formed on the complete photosensitive drums 1M, 1C, 1Y and 1K. The black images are sequentially transferred onto the transfer material of the recording medium that is successively conveyed by the conveyor belt 6, and an image of a plurality of colors (a full color image in this embodiment) can be formed.

The scanning optical device 3 is a scanner unit that scans the photosensitive drums 1M, 1C, 1Y, and 1K with laser beams L1 to L4 (see FIG. 18) modulated based on the color image signals corresponding to the respective colors. A laser, a scanning mirror, a folding mirror (movably configured), and the like are provided.

The driving of the printer unit 102 is controlled by the printer controller PCON, and the processing unit for controlling the transfer material conveying device and the image forming unit is provided.

FIG. 18 is an enlarged sectional view of the main part around the conveyor belt 6 shown in FIG. 17, and the same parts as those in FIG. 17 are designated by the same reference numerals.

In the figure, a drive motor 9M for driving the photosensitive drum 1M and a drive motor 9 for driving the photosensitive drum 1C.
C, a drive motor 9Y for driving the photosensitive drum 1Y, and a drive motor 9K for driving the photosensitive drum 1K. The illumination lamps 12b-1 and 12b-2 illuminate a test pattern for registration correction, which is transferred so as to face the conveyance belt 6 in a direction orthogonal to the conveyance direction, for example. The imaging lens 12c forms an image of the reflected light of the test pattern on the conveyor belt 6 on the reading sensor 12a via the mirror 12e.

The drive motor 10 transmits a rotational force to the drive pulley 6a and causes the conveyor belt 6 to be orbited at a predetermined speed.

The conveyor belt 6 includes a drive pulley 6a, a driven pulley 6b, a tension pulley 6d, and a belt swing pulley 6e.
Is wound around the drive pulley 6a and the driven pulley 6b.
The portion of the conveyor belt 6 stretched between the photosensitive drums 1 is
M, 1C, 1Y. The portion in contact with 1K is the transfer portion. The belt rocking pulley 6e has a shaft 6e-1 which is fixedly mounted as shown in FIG. 19, such as a spherical helical bearing, which allows tilting of the shaft 6e-1 of the pulley 6e and a movable bearing 7 which is movable.
It is rotatably supported by 2. The movable bearing 72 is housed in a bearing box 73 guided by a guide 74 fixed in parallel with the moving direction of the conveyor belt 6. A feed screw 75 parallel to the guide 74 is screwed into the bearing box 73. A belt swing correction motor 76 such as a pulse motor is connected to the feed screw 75. When the belt 9 swinging corrective motor 76 is driven, the feed screw 75 rotates and the bearing box 73 moves to the bearing 7
It is guided by the guide 74 along with 2, and moves in parallel with the transport direction of the transport belt 6. For example, when the movable bearing 72 on the front side in FIG. 18 is moved to the right, the conveyor belt 6 comes closer to the back side due to the tension due to the shaft inclination. or,
When the belt swing pulley 6e is moved in the opposite direction, the conveyor belt 6 comes closer to the front side due to the tension due to the shaft inclination. Then, the greater the inclination of the shaft of the swing pulley 6e, the faster the speed of the conveyor belt 6 in one direction.

As shown in FIG. 18, an infrared light emitting element 77 for illuminating the outer surface of the end portion of the conveyor belt 6 and an infrared light receiving element sensor 78 are arranged outside the lower stretched portion of the conveyor belt 6. The infrared light from the infrared light emitting element 77 hits the surface of the conveyor belt 6, and the infrared light is reflected and detected by the infrared light receiving sensor 78 at the portion where there is a mark 79 (FIG. 20) described later, and the belt mark 79 is detected. Further, since the conveyor belt 6 is transparent, the portion other than the mark 79 is transmitted and is not detected by the infrared light receiving sensor 78.

FIG. 20 is an enlarged view of the conveyor belt 6 shown in FIG. 17 as seen from above. As shown in FIG. 20, in the present invention, the triangular mark 79 shown in FIG. 20 is written on the conveyor belt 6. The bottom of the mark 79 is parallel to the edge of the conveyor belt 6.

When the conveyor belt 6 moves and the mark 79 crosses the point where the infrared light emitting element 77 shown by X in the figure illuminates the conveyor belt 6, that is, the sensor detection point 81, the infrared light is reflected by the mark 79. During this time, the print controller PCON can detect the mark 79 by the infrared light receiving sensor 78. At this time, if the time when the mark 79 crosses the sensor detection point 81 is measured, the position of the conveyor belt 6 can be determined because the time when the mark 79 crosses the sensor detection point 81 differs depending on the swing state of the conveyor belt 6. For example, in the case of FIG. 20, as the mark 79 crosses the sensor detection point 81 as it swings toward the right side toward the upstream side in the belt conveyance direction, the time when the mark 79 crosses the sensor detection point 81 becomes shorter. It takes a longer time to cross the detection point 81. If the crossing time with respect to the sensor detection point 81 is measured in advance,
The swing amount of the conveyor belt 6 can be measured. Such calculation is performed by inputting the photoelectrically converted signal of the infrared light receiving sensor 78 to the print controller PCON. Then, the print controller PCON controls the belt swing correction motor 76 to correct the position of the conveyor belt 6.

FIG. 21 shows a position measurement algorithm based on the above algorithm. It is checked whether the infrared ray receiving sensor 78 has detected the mark 79 (step 1). Until the infrared sensor detects the mark 79 (step 1)
To continue. When the infrared light receiving sensor 78 detects the mark 79, the time until the mark 79 is no longer detected is measured (step 2). The belt swing position is determined from the measurement time (step 3).

As described above, it has been shown that the swing amount of the transport belt 6 can be measured by the transport belt 6 with the mark 79 and the infrared light receiving sensor 78. If the amount of swing of the transport belt 6 as described above is found, the transport belt 6 is moved in the direction opposite to the swing direction of the transport belt 6 by the belt swing pulley 6e.
Belt swing correction motor 7 so as to move in the axial direction of
By biasing 6 by a specified amount, the swing of the conveyor belt 6 is suppressed to a minimum and the swing is eliminated.

[Sixth Embodiment] In the fifth embodiment, the belt swing position can be measured, but in the sixth embodiment, the belt swing direction and the belt swing speed can be measured.

FIG. 22 shows a flowchart of the sixth embodiment.

The belt swing position is measured as shown in the fifth embodiment (step 1). The belt swing position is stored (step 2). The position data before one rotation is read (step 3). The swing speed and direction are determined from the difference between the current position data and the position data one rotation before (step 4).

It has been shown that by storing the position data as described above, the swing speed of the conveyor belt 6 and its direction can be detected. Therefore, the print controller PCON promptly corrects the swing on the conveyor belt 6,
Oscillation can be prevented.

Examples 7 to 8 are intended to solve the problem in controlling the position of the conveyor belt only from one side of the conveyor belt in response to the problem 4.

[Embodiment 7] The construction of the image forming apparatus of this embodiment is the same as that of the previous embodiment, and the conveyor belt is moved in the axial direction of the swing pulley by tilting the swing pulley. ing. The different points will be described below.

FIG. 23 shows a flowchart of the belt swing control method according to the present invention. A left-end detection sensor (not shown) of the conveyor belt 6 (here, the left-end detection sensor of the conveyor belt 6 is a sensor that detects the belt end on the left side of the conveyor belt 6 when viewed toward the downstream side in the traveling direction of the conveyor belt 6. 6 Print controller PCON not shown on the left edge
Check whether or not is detected (step 1). If it is determined that the print controller PCON has detected,
The belt swing correction motor 76 is rotated so that the front side of the belt swing pulley 6e in FIG. 19 of the previous embodiment moves to the right by a specified value so that the conveyor belt 6 moves to the right (step 2). ). Print controller PC
When ON does not detect the left end of the conveyor belt 6, a belt right end detection sensor (not shown) detects the right end of the conveyor belt 6 toward the downstream side in the belt traveling direction. It is checked whether or not the right end of the conveyor belt 6 is detected (step 3). If it is determined that the print controller PCON has detected the right end of the conveyor belt 6, the belt swing correction motor 76 is moved to the left side in FIG. 19 so that the conveyor belt 6 moves to the left. It is rotated so as to move toward the specified value (step 4).

As described above, the print controller PCON provides the oscillation correcting motor with independent control values for the oscillations to the left and right, so that it is possible to cope with the case where the mechanical displacement easily occurs in one direction. It becomes possible to control.

[Embodiment 8] In Embodiment 7, the swing amount is controlled by giving different control values to the swing to the right and the swing to the left. It is shown that the rocking speed can be controlled by changing the value with time.

FIG. 24 shows a flowchart of the eighth embodiment. It is checked whether or not the print controller PCON (not shown) detects the left end of the conveyor belt 6 by the belt left end detection sensor (step 1). If the print controller PCON determines that the left end of the conveyor belt 6 is detected, the belt swing correction motor 76 is moved to the front side of the belt swing pulley 6e in FIG. 19 so that the conveyor belt 6 moves to the right. The belt swing correction motor 76 is rotated by a fixed amount so as to move it to the right by a specified value (step 2). It is checked whether or not a certain time has passed since the belt swing correction motor 76 was rotated (step 3). If a certain period of time has passed since the belt swing correction motor 76 was rotated, the process returns to (step 2) and the belt swing correction motor 76 is rotated by a specified amount in the same direction as the above. If a certain time has not passed,
It is checked whether or not the belt left end detection sensor detects the left end of the conveyor belt 6 (step 4). When the left end of the belt is continuously detected, the process returns to (step 3). When the belt left end detection sensor does not detect the belt left end, the conveyance belt 6 is no longer located at the left end, and the control is stopped.

The conveyor belt 6 is detected by the belt left end detection sensor.
If it is determined that the print controller PCON (not shown) has not detected the left end of the print controller PCON, it is determined whether the print controller PCON (not shown) has detected the right end of the conveyor belt 6 by the belt right end detection sensor (step 5). If the print controller PCON determines that the right end of the conveyor belt 6 has been detected, the belt swing correction motor 76 is moved to the left side in FIG. 19 so that the conveyor swing belt 6 moves to the left. Belt swing motor 7
It is checked whether or not a fixed time has elapsed after rotating 6 (step 7). If a certain period of time has passed after rotating the belt swing correction motor 76, the process returns to (step 6) and the belt swing correction motor 76 is rotated by the regulation value in the same direction as the above. If the predetermined time has not elapsed, it is checked whether the belt right end detection sensor detects the right end of the conveyor belt 6 (step 8). If the detection continues, the process returns to (step 7). If the belt right end detection sensor does not detect the belt right end, the control is stopped because the conveyor belt 6 is no longer located at the right end (step 8).

The specified value amount for rotating the motor every fixed time gives an optimum value depending on the state of the belt end sensor and the time.

The ninth and tenth embodiments correspond to the above-mentioned problem 5, and prevent the irradiation light of the illumination lamp of the reading device used for registration registration and the like from being reflected on the reading sensor due to the scratch on the conveyor belt.

[Embodiment 9] FIG. 25 is a schematic vertical sectional view of an embodiment 9 in which the present invention is applied to an electrophotographic color copying machine. In the figure, the same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. A sheet feeding device 65 is provided on one side in the copying machine body 30, that is, on the right side in FIG. 25, and a transfer material discharge port 24 is provided on the other side on the left side in FIG. 25.
The fixing device 8 is disposed inside the discharge port 24 so as to be adjacent thereto. Further, a driven pulley 6b is provided in the vicinity of the sheet feeding device 65 in the copying machine main body 30, and a drive pulley 6a is provided in the vicinity of the fixing device 8.
An endless transport member, for example, a transport belt 6, is wound between a and 6b. A tension pulley 6d is provided below the drive pulley 6a so as to come into contact with the conveyor belt 6 from the circumferential side of the conveyor belt 6 and freely adjust the tensile force of the conveyor belt.

The paper feeding device 65 is a paper feeding cassette 61 which is detachably attached to the copying machine main body 30, a rotatable paper feeding roller 62 which is provided at a mounting portion of the copying machine main body 30 to which the paper feeding cassette 61 is attached, and this feeding paper. A paper feed guide 6 for guiding the transfer material P fed into the copying machine main body 30 by the paper roller 62.
3. A pair of registration rollers 64 that receives the transfer material P guided by the paper feed guide 63 and sends the transfer material P onto the conveyor belt 6 on the driven pulley 6b side at a predetermined timing,
It is composed of a sensor (not shown) which outputs a predetermined signal when the leading end of the transfer material P moving in the paper feed guide 63 is detected. The sheet feeding device 65 performs a function of placing the transfer material P on the conveyor belt 6 from the driven pulley 6b side. The transfer material discharge port 24 is provided with a paper discharge tray 117 that is detachable from the copying machine main body 30.

Image forming units PM, PC, PY, and PK
Of the sensors 66M and 66 on the upstream side in the transport direction of
C, 66Y and 66K are provided, and these sensors detect when the leading edge of the transfer material P conveyed by the conveyor belt 6 has passed and detect the respective image forming units PM, PC, PY and. The signal for starting the image forming process in the PK is output to the electronic circuit control means, that is, the control unit.

In the color copying machine having the above construction, a cut sheet-like material is used as the transfer material P as shown in the figure, and the transfer material P is sent out from the paper feeding cassette 61 and fed by the paper feeding guide 63 of the paper feeding device 65. When the inside of the image forming unit PM, P is moved, the tip of the image forming unit is detected by the sensor (not shown), and the image forming units PM, P are detected by a detection signal output from the sensor.
C, PY and PK photosensitive drums 1M, 1C, 1Y and 1
K starts rotating. The drive pulley 6a is also driven at the same time, and the conveyor belt 6 is driven in the direction of the arrow in FIG. The transfer material P is guided by the paper feed guide 63. When the transfer material P is guided by the paper feed guide 63 and placed on the conveyor belt 6, it receives corona discharge from the adsorption charger (not shown) and is reliably adsorbed on the conveyor belt 6. With the movement of the conveyor belt 6 in the direction of the arrow in FIG. 25, the sensors 66M, 66C, 66Y at the tip of the transfer material P,
And 66K, the image forming process for the corresponding photosensitive drums 1M, 1C, 1Y and 1K is sequentially started. That is, the magenta image is formed on the photosensitive drum 1M of the first image forming unit PM and the second image forming unit P is formed.
A cyan image is formed on the photosensitive drum 1C of C, a yellow image is formed on the photosensitive drum 1Y of the third image forming unit PY, and a black image is formed on the photosensitive drum 1K of the fourth image forming unit PK. To be done. By the movement of the conveyor belt 6, the transfer material P is transferred to the first to fourth image forming portions PM, P.
The photosensitive drums 1M, 1C, 1Y, and 1K of C, PY, and PK are sequentially passed under and are conveyed toward the fixing device 8.
The transfer chargers 7M, 7C, 7Y, and 7K of the image forming units sequentially transfer the visible images of the respective colors formed by the image forming apparatuses on the transfer material P so as to combine the color images. After the transfer material P has passed through the fourth image forming portion PK, the transfer material P is discharged by the static eliminator (not shown) to which an AC voltage is applied, and is separated from the conveyor belt 6. Conveyor belt 6
The transfer material P separated from is transferred to the fixing device 8, and after the visible image transferred in the fixing device 8 is fixed, the transfer material P is discharged from the transfer material discharge port 24 to the discharge tray 117, thus making one copy. The cycle ends.

The apparatus according to the ninth embodiment has a mechanism for correcting the image shift (color shift) for each image forming section as described below. The endless conveyor belt 6 is idled in a state where the transfer material P is not conveyed, and the test pattern of each color is transferred onto the conveyor belt 6 at a predetermined timing. Generally, a test pattern having a cross shape is used, and the test patterns of respective colors are sequentially read by the pattern reading device 12 of FIG. As described with reference to FIG. 27, the reading device 12 includes the reading sensor 12 a of the solid-state image sensor CCD and the imaging lens 12.
c, a visible light cut filter 12d, and an illumination lamp 12b, and a test pattern image formed of toner that diffuses and reflects infrared light is formed on the reading sensor 12a through the cut filter 12d and the lens 12c. The test pattern is detected by the output. At this time, the illumination lamp 12b is installed at an angle to the conveyor belt 6 so that the specularly reflected light of the illumination lamp 12b on the conveyor belt 6 does not enter the reading sensor 12a. The reading sensors 12a are arranged in a line in a direction orthogonal to the carrying direction at least longer than the size of the test pattern, and the position in the carrying direction (hereinafter referred to as the sub-scanning direction) is a direction orthogonal to the carrying direction depending on the passage time of the reading sensor 12a. Position (hereinafter referred to as the main scanning direction) is determined by the range of increase in the output of the reading sensor. Then, the positional deviation of the other three colors is corrected with reference to one certain color. FIG. 26 shows a block diagram of the correction circuit. The test pattern signal L503 of each color sequentially read by the reading sensor 12a is subjected to processing such as amplification, DC reproduction, A / D conversion, etc. by the CCD driver 95, and is registered as a digital signal L505 in the registration controller 9.
Sent to 6. The sent signal is used by the CPU control to calculate the amount of color misregistration of the other color with respect to the reference of one color, and as a result, the data signal L of the writing position is written.
509 is sent to the system controller 97, and the optical path and light dew length of each laser beam are adjusted. Also, the data L51
1 is sent to the mirror motor driver 98. The mirror motor driver 98 outputs an appropriate pulse to each motor MM, MC, M.
Y, MK, and adjusts the angle of the mirror arranged in the optical path between the laser light source and the photosensitive drum included in the scanning optical devices 3M, 3C, 3Y, 3K according to the rotation amounts of these motors. These corrections are supplied to the registration controller 96 by the activation signal L510 from the system controller 97 and executed.

In this embodiment, as the material for the endless conveyor belt 6, a resin (for example, polyurethane) in which carbon is kneaded so that the absorption rate of infrared light is 80% or more and the diffuse reflectance is 5% or less is used. Also, the diffuse reflectance of toner is 40
% Was used. Therefore, each pulley 6a, 6b, 6d
The influence of the scratches 6x on the back of the belt caused by crevices (surface roughness), shavings, dust, or rubbing against various backab members is that the illumination light for the scratches 6x in FIG. The specularly reflected light is absorbed by and is not transmitted through the conveyor belt 6.
It can be prevented because it is not taken into D. Further, even if scratches 6x on the surface of the conveyor belt 6 caused by the transfer material, rubbing by the photosensitive drum, and belt cleaning means (not shown in FIG. 25), the absorption rate hardly changes,
Since the diffuse reflectance is low, the output of the CCD of the reading sensor 12a is stable without being affected by the scratch 6x, so that erroneous detection can be prevented and the color misregistration can be surely corrected. In this embodiment, a toner having a diffuse reflectance of 40%, a conveyor belt absorptance of 80% or more, and a diffuse reflectance of 5% or less with respect to infrared light was used. This value is the performance of the CCD of the reading sensor 12a. It is decided comprehensively including the above.

[Embodiment 10] In an apparatus similar to that of the ninth embodiment, the endless conveyor belt 6 has a base resin and an infrared ray absorptivity of 80% or more and a diffuse reflectance of 5% or less. As described above, a resin formed by coating or coating with another resin was used. Also in the tenth embodiment, it is possible to prevent the reading of the test pattern due to the scratch on the conveyor belt.

In Examples 11 to 13, the resist correction test pattern with the toner of the color that cannot detect the reflected light due to the spectral characteristic is used for the resist correction of the color toner that can be detected due to the spectral characteristic on the conveyor belt. An object of the present invention is to obtain an image forming apparatus that detects registration deviation by transferring the test pattern on the test pattern and reading the overlapping amount with a sensor.

[Embodiment 11] FIG. 31 is a sectional view for explaining the structure of the main part of an image forming apparatus showing Embodiment 11 of the present invention. The same parts as those in FIG. 50 are designated by the same reference numerals. .

In FIG. 31, the video signal output from the registration correction pattern generation control unit 27a is output to the laser driver 27b, and the photosensitive drum is passed through each laser scanning optical device 3M, 3C, 3Y, 3Y. An electrostatic image corresponding to the registration correction test pattern is formed at desired positions of 1M, 1C, 1Y, and 1K.

In the image forming apparatus thus constructed, a predetermined registration pattern forming process on the photosensitive member is started by the test pattern forming means (each of the first to fourth image forming portions PM, PC, PY, PK). Then, the transfer control unit (in this embodiment, the registration correction pattern generation control unit 27a) causes the color having no reflection characteristic on the test pattern of the color developer having the reflection characteristic transferred onto the conveyor belt 6. The multiple transfer of the test pattern of the developer (black in this embodiment) is controlled, and the multiple transfer of the color developer test pattern having the reflection property and the test pattern of the color developer having no reflection property is performed so as to form an overlapping region. It is also possible to let.

When the test pattern reading device 12 detects the registration registration test pattern of each color transferred onto the conveyor belt 6 in this manner, the timing control means (also serving as the digital image processing section 27) of the reading device 12 is operated. Control the image formation timing based on the output,
Align the resist.

32 and 33 are schematic diagrams (FIG. 32) of the test pattern 22 transferred onto the conveyor belt 6 and a reflection signal (FIG. 33) at that time. The test pattern 22 of the color toner TK having no reflection characteristic is multi-transferred onto the test pattern 22 of the color toner (magenta toner) TM having the reflection characteristic, and the non-overlapped portion (position x1,
The registration amount can be obtained by detecting the size L of (between x2). As shown in FIG. 33, between the positions x1 and x2, the output voltage signal V of the reading sensor 12a is large in the reflected light from the test pattern 22 of the illumination lamp 12b.

34 to 37 show overlapping patterns when a square pattern 0 is used as a registration correction test pattern. The test pattern 2 of the color toner TK (black) in which the diagonal line has no reflection characteristic
It is 2. By detecting the L shape and size of the non-overlapping portion, the registration amounts L1 and L of the color image forming portion with respect to the image forming portion PK (black station) are detected.
2 can be detected.

In this embodiment, toner having no reflection characteristic is used.
- Is required to be transferred from above the toner having reflective properties.
Toner that does not have reflection characteristics in the final image forming portion PK
It is desirable to place TK.

Referring to FIG. 38, the transfer processing of the square pattern will be described with reference to the timing chart.

As shown in this figure, a predetermined time tm, from the rising of the reference ITOP shown in FIG.
Each photosensitive drum 1 at the timing of tc, ty, tk
M. When laser exposure for image formation is started with respect to 1C, 1Y, and 1K, on the conveyor belt 6 or the transfer material P.
It is constructed so that the four colors just overlap. Therefore,
As shown in FIG. 39, in order to superimpose a black (hatched portion in FIG. 39) test pattern on the magenta M, cyan C, and yellow Y test patterns, the black timing should be printed and transferred at the magenta, cyan, and yellow timings. Good.

FIG. 39 is a schematic diagram showing a test pattern transfer state of the present embodiment, in which pairs are transferred so as to face a predetermined position in the width direction orthogonal to the arrow a in the conveyance direction of the conveyance belt 6. . The shaded area in the drawing indicates that the black K pattern of the fourth image forming portion PK is transferred so as to be superimposed on the magenta M, cyan C, and yellow Y color toners.

The test pattern for registration correction of each image forming portion transferred in this manner is detected by the reading device 12 provided downstream of the conveyor belt.

[Embodiment 12] FIG. 40 schematically shows a test pattern detected when both the superposed toners have a spectral reflection characteristic, for example, when the toners TM and TC have a color shift of the length L. It is shown. In FIG. 41, the horizontal axis shows the positions x1, x2, x3, and x4 of the test pattern 22 in the moving direction of the conveyor belt of FIG. 40, and the vertical axis shows the output voltage signal V of the reading sensor 12a.

According to this characteristic, the overlapped test pattern portions x2 and x3 have a high reflection signal V, and the overlap amount can be detected by identifying this. According to this method, if the black toner TK shown in FIGS. 34 to 37 is replaced with the color toners TM, TC, and TY, the two test patterns cannot be distinguished. For this reason, a recognizable identification mark pattern must be formed on either of the test patterns. 42 to 4
5 shows an example of the pattern of this identification mark. The identification mark 22a was attached to the test pattern 22 (TC) indicated by the diagonal lines.

[Embodiment 13] FIGS. 46 and 47 schematically show test patterns detected when the toner TY to be superposed has a spectral reflection characteristic and the lower toner TK is a toner having no spectral reflection characteristic. It is shown in.

According to this characteristic, in the superimposed test pattern portion, the reflection signal becomes low due to the superposition, and the superposition amount and direction can be detected by discriminating between the portions x3 and x4 having high reflection characteristics. You can

In the above embodiments, the four-drum type full-color type image forming apparatus shown in FIG. 48 has been described as an example, but the present invention is also applicable to a full-color copying machine of the type in which color developers are multiple-developed on a photosensitive drum. Is applicable.

Examples 14 to 18 correspond to the problem 7, and provide an image forming apparatus which always obtains a stable image by detecting a micro image forming state by reading a test pattern.

[Embodiment 14] FIG. 55 shows an MT according to the present invention.
An outline of a method for determining an appropriate transfer condition by F detection is shown in a flowchart. FIG. 4 shows an example of an image forming apparatus equipped with a reading device having a CCD for MTF detection.
Since the configuration of the image forming unit is the same as that of the conventional example, detailed description will be omitted. The test pattern 22 illuminated by the test pattern illumination lamp 12b passes through the imaging lens 12c and is imaged by the CCD sensor provided as the reading sensor 12a.

The test pattern 22 is formed by the following steps in the MTF (Modulation Transfer F).
unction; spatial transfer function) is detected.

FIG. 56 is an enlarged view of the test pattern 22. In a copying machine capable of reproducing continuous gradation, PWM (Puls Width) is a means for exposing continuous gradation.
hMethod) is widely used as a known technique. The PWM is a combination of the triangular wave 85 of FIG. 57 having a cycle of 200 lpi (elp eye) and the image signal 82 of FIG. 57 created based on the image signal, that is, the overlapping portion of both waveforms, that is, the image signal 82. This is a method in which the portion in which the length of the horizontal axis in which the top portion cuts one triangular wave 85 is the length of the active signal is the image recording signal 83 as shown in FIG. Therefore, in the formed image, a peculiar pattern of vertical stripes of 200 lpi (LP eye) due to the triangular wave 85 is recognized.

Next, the CCD reading circuit of the reading sensor 12a will be described. The CCD sensor is driven with a constant frequency. The drive frequency is determined by the size of one pixel of the CCD, the optical magnification, and the transport speed of the transport belt 6. For example, the size of one pixel of CCD is (sub scanning direction × main scanning direction) 18 μm × 13 μm, and optical magnification is 1:
In the case of 1, the transport speed is 120 mm / sec, the CCD driving frequency is 123.4 nsec. This CCD clock frequency is also used as a memory driving frequency when the CCD signal is taken into the memory 84 shown in FIG. When the optical image of the test pattern 22 is projected onto the CCD of the reading sensor 12a, the CCD outputs a voltage that changes relative to the light and shade of the optical image. The voltage from each pixel is taken into the memory 84 after 8-bit A / D conversion which is taken out line-sequentially is performed. At this time, it is more desirable to add a circuit for removing the reset signal included in the CCD output.

FIG. 59 shows the state of the memory after it has been taken into the memory 84. The PWM line of the test pattern is reproduced on the memory 84. Pmax in FIG. 59 is P
The toner image portion of the WM line is shown, and Pmin indicates a space between the toner image lines. In the ideal image forming means, Pmax is equal to the CCD output when the maximum density of the toner image is detected, and Pmin is equal to the CCD output when the toner image is not detected at all. However, in the image forming apparatus of the embodiment, the PWM line is disturbed due to the influence of the image condition, etc., and as a result, the ideal system Pmax-Pmi
It is obtained as the output of the CCD which is narrower than n. That is, the value of MTF becomes 1.0 or less. The values of Pmax and Pmin are used to calculate the MTF. The calculation formula is given as follows.

TMF = (Pmax-Pmin) / (Pm
ax + Pmin) In the MTF calculation based on this test pattern, a high quality image is always obtained by continuously forming test patterns while changing one condition of the image forming means and selecting the image forming condition with the best MTF.

Next, a method for obtaining the optimum transfer condition by obtaining the MTF peak while changing the transfer current will be described.

When determining the proper transfer current, the transfer current when creating the test pattern is set to, for example, 0 μA to 500 μA.
10 types of test patterns are created by shaking every 50 μA up to A. The material of the transfer material conveying belt 6 used in this embodiment is made of bolyfucca vinylidene 0.1 mm thick and volume resistivity 1
It is 0 × 10 14 Ωcm. The curve indicated by the symbol a in FIG. 60 is the relationship between the test patterns detected by the sensor and the MTFs when the transfer current is changed when the image forming apparatus is installed at room temperature of 23 ° C. and absolute humidity of 60%. Indicates. The MTF shows a peak value when the proper transfer current is 250 μA. The change in transfer current and the change in MTF at room temperature of 20 degrees Celsius and absolute humidity of 10% are shown by the curve b in FIG. In the above environment, the MTF shows a peak value at 350 μA. That is, the test pattern is output while changing the transfer condition, and the TMF of each test pattern is further output.
It is possible to determine the optimum transfer condition by detecting the peak of MTF change and the peak of MTF change.

[Embodiment 15] This embodiment shows changes in the contact amount and MTF when the contact amount of the transfer pressing mylar 59 shown in FIG. 63 is changed. The same material for the transfer material transport belt as in Example 14 was used, and the installation environment was room temperature 23 ° C. and absolute humidity 6
The transfer current was 0% and the transfer current was 250 μA. In FIG. 61, the linear pressure of the transfer pressing mylar 59 is changed from 0 g / cm to 30 g / cm.
The change of MTF when changing every 5 g to cm is shown. At this time, the MTF shows a peak when the linear pressure is 15 g / cm, and the contact pressure of the transfer pressing mylar is 15 g / cm.
It turns out that is optimal.

[Embodiment 16] In this embodiment, the rotational speeds of the transfer material conveying belt 6 or the transfer drum 6D and the photosensitive drum 1 provided as an intermediate rotating member shown in FIG.
By changing the rotational speed of D (hereinafter referred to as the peripheral speed), the relative speed is changed to change the transfer efficiency, each MTF at that time is detected, and the optimum transfer is obtained by obtaining the MTF peak. The method for obtaining the conditions is shown below. As a method of changing the transport speed of the transfer material transport belt 6 of the transfer material transport means or the rotation speed of the transfer drum 6D of the intermediate transfer material support means, a rotary system independent of the rotary system of the photosensitive drum is used. This can be achieved by a well-known technique in which a pulse-controlled motor is used as the rotary drive device and the drive frequency of the motor is changed.

In FIG. 62, the peripheral speed of the transfer material conveying belt 6 or the transfer drum 6D is changed from 0% to 5% at 0.5% intervals so as to be slower than the peripheral speed of the photosensitive drum 1. MT
The change in F is shown. The material of the transfer material conveying means, the transfer current, and the linear pressure of the pressing mylar are the same as in the above embodiment. At this time, the MTF showed a peak at the peripheral speed with a delay of 1.0%.

[Embodiment 17] FIG. 63 shows an example in which a test pattern is detected on the transfer drum 6D. The CCD reading sensor 12a and the illumination lamp 12b are the transfer drum 6
It is installed close to the surface of D. Normal photosensitive drum 1
Light irradiation shortens its life. Therefore, it is not preferable to irradiate the photosensitive drum 1 with unnecessary light. Therefore, it is effective to detect the test pattern on the transfer drum by the CCD sensor as in the present embodiment.

[Embodiment 18] FIG. 64 shows an example in which a test pattern is detected on the intermediate transfer drum 6ID. C
A CD reading sensor 12a and an illumination lamp 12b are installed close to the surface of the intermediate transfer drum 6ID. In the image forming apparatus according to this embodiment, the color toner images sequentially formed on the photosensitive drum 1 are sequentially transferred onto the intermediate transfer drum 6ID in the order of magenta, cyan, yellow, and black, and then contact the intermediate transfer drum 6ID. The transferred material P is collectively transferred. M of the image with such a configuration
Detecting TF is effective because it is close to the final image. However, the test pattern must be output at a timing that does not overlap on the intermediate transfer drum.

[Embodiment 19] The above MTF detection can be applied to an image forming apparatus having a plurality of photoconductors. Magenta,
In FIG. 4, cyan, yellow, and black image forming units are arranged in series, and a transfer material conveying device 60 is provided below the image forming units.
In the image forming apparatus, the test pattern 22 is formed on the conveyor belt 6 and detected by the pattern reading device 12 provided at the rear of the final image forming section PK.

The twentieth and twenty-first embodiments correspond to the problem 8 and remove the electrostatic charge by the cleaning means of the conveyor belt.

[Embodiment 20] FIG. 66 shows Embodiment 20 and is a schematic sectional view in which the present invention is applied to an electrophotographic color copying machine. The part of the conveyor belt excluding the charge removal and cleaning is as described with reference to FIG. 25, and the repeated description is omitted.

An adsorption charger (not shown) is provided between the first image forming section PM and the sheet feeding device 65, and this adsorption charger is a transfer material supplied from the sheet feeding device 65. Corona discharge is performed in order to ensure that P is attracted to the conveyor belt 6. On the other hand, a static eliminator (not shown) is provided almost directly above the drive pulley 6a between the fourth image forming unit PK and the fixing device 8. The static eliminator is attracted to the conveyor belt 6. An alternating voltage is applied in order to separate the transfer material P that is present.

In this embodiment, with respect to the conveyor belt 6 which is the conveyor of the transfer material, a cleaning means 90 for cleaning the dirt adhering to the transfer material mounting surface is provided. The cleaning unit 90 includes a frame 91, a fur brush 92, and a drive motor (not shown) that drives the fur brush. The fur brush 92 has its axis centered in a direction substantially orthogonal to the moving direction of the conveyor belt 6, and its rotation direction is defined by the moving direction of the carrying belt 6 and the moving direction of the peripheral surface of the fur brush 92 at the position in contact with the carrying belt 6. The reverse rotation in the opposite direction is performed by the drive motor at about 3000 rpm. The drive of the fur brush 92 is controlled by a microcomputer provided in the main body and is turned on and off at a predetermined timing. Further, adjacent to the cleaning means 90, charge removing chargers 93a and 93b which interlock with the fur brush 92 and generate corona discharge are installed on the upstream side in the moving direction of the conveyor belt 6 so as to sandwich the conveyor belt 6. Charge elimination charger 93
By means of a and 93b, it is possible to remove the charges on the conveyor belt 6 generated by the series of image forming processes. Therefore, the residual toner (fog toner) transferred on the conveyor belt 6 and the electric coupling force between the conveyor belt 6 can be removed, so that the cleaning means 90 can easily remove the fog toner.

Further, similarly, neutralization chargers 93c and 93d are arranged between the cleaning means 90 and the driven pulley 6b.
Therefore, it is possible to remove the charge of the transfer belt 6 that is frictionally charged by the fur brush 92, and it is possible to always stably adsorb the transfer material P to the transfer belt 6 and transfer the toner image. Static elimination chargers 93a, 93b, 93c,
Since a high AC voltage is applied to 93d, the latitude is wide with respect to static elimination, but each DC component can be adjusted in preparation for obtaining the optimum value.

FIG. 67 is a flow chart of apparatus control of this embodiment, and FIG. 68 is a horizontal axis showing time Ti (i = 1, 2 ...).
The timing chart which shows is shown. When the user receives a command to start copying, in step 1 (T1), the photosensitive drums 1M, 1C, 1Y, 1K, the conveyor belt 6, and the fur brush 92 are driven, and at the same time, the AC high voltage is also applied to the charge eliminating chargers 93a to 93d. The charge is applied to the conveyor belt 6 to remove electricity. Next, as described above, the transfer material P is fed in step 2 (T2), and the timing of feeding the transfer material P and the timing of the visible image formed on the photosensitive drums 1M to 1K are determined in step 3 (T3). The respective color images are sequentially superimposed to form a color image on the transfer material P. In step 4 (T3 '), the above operation is repeated when a plurality of sheets are continuously copied by the user's designation. The fur brush 92 and the static eliminator chargers 93a to 93d continue to operate during image formation to constantly remove the residual toner and dust transferred onto the conveyor belt 6, and to slide the fur brush 92 and the conveyor belt 6 together. Since recharging of the conveyor belt 6 due to rubbing can be removed, stable adsorption, conveyance, transfer and separation of the transfer material P can be performed even when a large number of continuous copies are made, and back stain of the transfer material P can be prevented. At step 5 (T4), a series of image formation is completed, and when a paper discharge sensor (not shown) detects paper discharge, then step 6
First, at (T5), the photosensitive drums 1M to 1K, the conveyor belt 6,
The fur brush 92 is stopped at the same time, and step 7 (T6)
Then, the static elimination chargers 93a to 93d are cut off after a while. Therefore, it is possible to prevent residual charge removal due to movement of the conveyor belt 6 due to inertial force when the conveyor belt 6 is stopped. As described above, it is possible to reduce the wait time and perform stable image formation during the next image formation.

[Embodiment 21] FIG. 69 shows Embodiment 2 of the present invention.
It is a figure showing 1 and the same code | symbol as Example 20 has the same function. In this embodiment, the conductive brush 94 grounded to the copying machine main body 30 is arranged between the cleaning means 90 and the driven pulley 6b, and the same effect as in the previous embodiment 20 is obtained. It is impossible to adjust the static elimination like the 20th embodiment, but there is an advantage that it does not cost.

FIG. 70 is a flow chart of device control in this embodiment, and the operation sequence is the same as in the previous embodiment.
The static electricity is constantly removed by the conductive brush 94 during the movement of the conveyor belt 6.

[0160]

As described above, according to the first aspect of the present invention, since the transfer material conveying belt supporting means is provided, the transfer material conveying belt does not vibrate vertically, so that the test pattern can be reliably detected.

In the second aspect of the present invention, in the first aspect of the present invention, the transfer material conveying belt supporting means is provided with the adsorbing means for adsorbing the conveying belt. Does not vibrate.

In the third invention of the present invention, since the transfer material transport belt supporting means is the upper and lower support members in the first invention, there is little resistance to the movement of the transfer material transport belt, and the transfer material transport belt is Does not vibrate vertically.

In the fourth aspect of the present invention, since the upper and lower support members can be brought into contact with and separated from the transfer material transport belt in the third aspect of the invention, abrasion of the transfer material transport belt is prevented.

According to the fifth aspect of the present invention, in the fourth aspect, the upper and lower support members are contacted with and released from the transfer material transport belt according to the presence or absence of test pattern formation. Therefore, the transfer material transport belt is used at the time of transfer after image formation. Does not give extra load to.

According to a sixth aspect of the present invention, the angle in the plane projected onto the conveyor belt is within 60 degrees with respect to the direction in which the conveyor belt moves in the direction in which the reading device for reading the test pattern illuminates. It is possible to prevent reflected / scattered light from a scratch generated in the transport direction due to the durability of the transport belt from entering the reading sensor in the reading device, and thereby to reliably read the test pattern. That is, since the false detection of the test pattern can be reduced, the resists of the multiple images can be reliably aligned and a high quality image can be output.

According to the seventh aspect of the present invention, by providing a mark on the conveyor belt and a means for reading the mark, the oscillating position and oscillating speed of the conveyor belt,
There is an effect that the state of the belt deviation amount such as the swing direction can be accurately detected.

According to the eighth aspect of the present invention, the means for correcting the deviation of the conveyor belt is controlled by the signal detected by the means for detecting the deviation of the conveyor belt. It is possible to more appropriately control the belt position according to the leaning state.

According to the ninth aspect of the present invention, a plurality of images for forming a desired image by reading a test pattern for registration correction on the conveyor belt or for correcting image forming means with a reading device. An image forming apparatus having a means for recording on a transfer material by using a forming means, wherein the image forming apparatus has a conveyor belt having an absorptance for infrared light larger than a transmissivity. Since the position of the test pattern is detected by the difference in the reflectance of the developer on which the test pattern is formed with respect to infrared light, the scratch on the back of the conveyor belt can be ignored and the scratch on the surface of the conveyor belt can also be absorbed. Since the test pattern is not lowered, it is possible to always detect the test pattern stably and prevent the misoperation of the image color misregistration correction control due to the misdetection. Therefore, it becomes easy to select the material of the conveyor belt, and it is possible to extend the service life because it is possible to use a material that cannot be used conventionally due to scratches.

According to the tenth aspect of the present invention, in the ninth aspect, since the conveyor belt is made of a resin in which carbon is kneaded, the light absorptivity can be increased and the reflectance can be decreased, which is different from the developer having a high reflectance. And the effect of the ninth invention can be easily achieved.

According to the eleventh aspect of the present invention, the spectral reflection characteristic of the developer in the image forming portion, which serves as the resist reference, is a characteristic that the test pattern reading device does not have sensitivity, and the spectral reflection characteristics of the developers of other colors. The characteristic is sensitivity, and the resist amount can be detected by overlaying the test pattern of the reference image forming unit on the test pattern of the image forming unit whose registration is read, and reading the overlayed test pattern. Since the image forming apparatus is characterized, the reading device can easily identify and detect the test pattern for each registration correction even if the developer has no spectral reflection characteristic. Therefore, the registration of each color developer can be accurately corrected, and a clear full-color image with no color shift can be formed.

According to the twelfth aspect of the present invention, the pattern forming means for forming a predetermined test pattern on the image carrier and the pattern on the image carrier or the transfer material formed by the pattern forming means are provided. On the conveyor belt to convey,
Alternatively, it has a reflected light amount detecting means for detecting the reflected light amount of the test pattern on the intermediate transfer material carrier in a minute area, and the reflected light amount movement pattern information detected by the reflected light amount detecting means allows the image forming apparatus Since the image forming apparatus is characterized by detecting the image forming state, continuously changing the image forming condition and continuously detecting the image forming state, and obtaining the optimum value of the image forming condition based on the detection result. , Now it is possible to obtain consistently high quality images.

The thirteenth invention of the present invention is the twelfth invention, wherein the image information of the minute area is detected in the minute area where the reflected light amount of the test pattern is minute, the test pattern is created while changing the transfer condition, and the MTF thereof is created. Is detected and the peak of the spatial transfer function MTF is detected, and the transfer condition is optimized at the peak point, so that a consistently high quality image can be obtained.

In the fourteenth aspect of the present invention, the image forming condition is at least one of the transfer current which is the transfer condition, the contact pressure of the transfer assisting means, and the peripheral speed between the photosensitive member and the transfer material conveying device. The image forming apparatus according to the twelfth aspect of the invention is characterized in that a consistently high quality image can be obtained.

The fifteenth invention of the present invention is the image forming apparatus according to the eleventh invention, characterized in that the reflected light amount detecting means can read the reflected light amount in a minute area of 30 μm × 30 μm or less. A consistently high quality image can be obtained.

A sixteenth aspect of the present invention is directed to an image forming portion provided with an image bearing member on which a visible image is formed, adjacent to the image bearing member, and a transfer material is fixed by electrostatic attraction and conveyed, A transfer device having a transfer material carrying sheet that passes a position for transferring a visible image and a cleaning means for cleaning the transfer material carrying sheet are provided. By providing the image forming apparatus characterized in that the charge removing means is provided upstream and downstream of the cleaning means,
The stains on the transfer material conveying belt are surely removed, and the charge on the transfer material conveying belt is removed by the cleaning means, which enables stable image formation on the transfer material. Therefore, since the cleaning means can be operated even during image formation, it is not necessary to clean the conveying means before or after image formation.
There is no waiting time for cleaning. In particular, it has become possible to reduce the operating time for a device with a long conveyor belt.

The seventeenth aspect of the present invention increases the durability of the cleaning means and the transfer material conveying belt because it is sufficient that the cleaning means operates during image formation.

In the eighteenth aspect of the present invention, in the sixteenth aspect of the invention, after the image formation is completed, the discharging unit terminates its operation after the conveying unit stops, so that the conveying unit moves due to inertia so that the portion where the discharging is not performed is eliminated. It can be prevented from remaining.

The nineteenth aspect of the present invention is applicable to the sixteenth aspect of the present invention, in which the conveying device has an endless flexible belt.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment in which the present invention is implemented.

FIG. 2 is a vertical cross-sectional view taken along the moving direction of the transfer material carrying sheet of FIG.

FIG. 3 is a perspective view of a third embodiment.

FIG. 4 is a vertical cross-sectional view of the image forming apparatus.

5 is a partially enlarged detailed view of FIG. 4. FIG.

FIG. 6 is a schematic vertical sectional view of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a transfer material carrying device and a test pattern reading device according to a fourth embodiment of the present invention.

FIG. 8 is a side view of the test pattern reading device of FIG. 7 according to the present invention.

FIG. 9 is a plan view showing an illumination direction of a test pattern reading device according to a fourth embodiment.

FIG. 10 is a side view of FIG. 9.

FIG. 11 is a front view of FIG. 9.

FIG. 12 is a reading CCD reading a test pattern.
It is a diagram showing the output of.

FIG. 13 is a plan view showing an illumination direction of a conventional test pattern reading device.

FIG. 14 is a side view of FIG.

FIG. 15 is a front view of FIG.

FIG. 16 is a diagram showing a CCD output of a reading sensor which reads a conventional test pattern.

FIG. 17 is a vertical cross-sectional view illustrating the configuration of the image forming apparatus according to the fifth embodiment of the present invention.

FIG. 18 is an enlarged cross-sectional view of an essential part around the conveyor belt shown in FIG.

FIG. 19 is a horizontal sectional view of the conveyor belt swinging device.

FIG. 20 is a plan view of a conveyor belt.

FIG. 21 is a flowchart illustrating a conveyor belt swing control algorithm according to a fifth embodiment of the present invention.

FIG. 22 is a flowchart illustrating a conveyor belt swing control algorithm according to a sixth embodiment of the present invention.

FIG. 23 is a flowchart illustrating a conveyor belt swing control algorithm according to a seventh embodiment of the present invention.

FIG. 24 is a flowchart illustrating a conveyor belt swing control algorithm according to an eighth embodiment of the present invention.

FIG. 25 is a vertical cross-sectional view of Examples 9 and 10 of the present invention.

FIG. 26 is a block diagram of color misregistration correction control according to Examples 9 and 10.

FIG. 27 is a vertical cross-sectional view of a test pattern reading device according to Examples 9 and 10.

28 is a diagram showing a CCD output of the reading sensor in FIG. 27. FIG.

FIG. 29 is a vertical cross-sectional view of a test pattern reading device when a conventional conveyor belt is used.

30 is a diagram showing a CCD output of the reading sensor in FIG. 29. FIG.

FIG. 31 is a vertical cross-sectional view illustrating a main part configuration of an image forming apparatus according to an eleventh embodiment of the present invention.

FIG. 32 is a vertical cross-sectional view illustrating a light reflection state at the time of superposing the developers.

33 is an output voltage V of the reading sensor in FIG.
FIG.

FIG. 34 is a plan view showing a pattern at the time of overlapping the developers.

FIG. 35 is a plan view showing a pattern at the time of superposing the developers.

FIG. 36 is a plan view showing a pattern at the time of superposing the developers.

FIG. 37 is a plan view showing a pattern at the time of superposing the developers.

38 is a timing chart showing data formation timing of a correction test pattern of the image forming apparatus shown in FIG.

FIG. 39 is a schematic diagram of a test pattern on a conveyor belt.

FIG. 40 is a vertical cross-sectional view for explaining a light reflecting state at the time of superposing the developers in Example 12 of the invention.

41 is a diagram showing an output voltage of the reading sensor in FIG. 40. FIG.

FIG. 42 is a plan view showing a pattern at the time of overlapping the developers.

FIG. 43 is a plan view showing a pattern at the time of overlapping the developers.

FIG. 44 is a plan view showing a pattern at the time of superposing the developers.

FIG. 45 is a plan view showing a pattern at the time of overlapping the developers.

FIG. 46 is a vertical cross-sectional view for explaining a light reflecting state at the time of superposing the developers in Example 12 of the invention.

47 is a diagram showing an output voltage signal V of the reading sensor in FIG. 46. FIG.

FIG. 48 is a vertical cross-sectional view showing an example of a 4-drum type color image forming apparatus.

FIG. 49 is a perspective view of a test pattern reading device for resist registration.

FIG. 50 is a timing chart showing a mark formation timing for resist registration.

FIG. 51 is a timing chart showing a mark formation timing for resist registration.

FIG. 52 is a diagram showing a spectral reflection characteristic of a color developer.

FIG. 53 is a diagram showing a spectral reflection characteristic of three-type mixed black.

FIG. 54 is a diagram showing a spectral reflection characteristic of carbon black.

FIG. 55 is a flowchart of an MTF detection method for transfer condition correction.

FIG. 56 is a plan view of a test pattern.

FIG. 57 is a diagram showing the synthesis of waveforms by PWM.

FIG. 58 is a diagram showing an image forming waveform by PWM.

FIG. 59 is a conceptual diagram on a memory.

FIG. 60 is a diagram showing the relationship between transfer current and MTF.

FIG. 61 is a diagram showing a relationship between a pressing mylar linear pressure and MTF.

FIG. 62 is a diagram showing a relationship between a peripheral speed difference between a photosensitive member and a transfer material conveying member in contact with the photosensitive member and MTF.

FIG. 63 is a vertical cross-sectional view of a device to which Examples 14 to 19 of the present invention are applied.

FIG. 64 is a vertical cross-sectional view of a device to which Examples 14 to 19 of the present invention are applied.

FIG. 65 is a vertical cross-sectional view showing a conventional example with respect to Examples 14 to 19.

FIG. 66 is a vertical sectional view showing the twentieth embodiment of the present invention.

FIG. 67 is a flowchart of Example 20 of the present invention.

FIG. 68 is a timing chart of Example 20 of the present invention.

FIG. 69 is a vertical sectional view showing Example 21 of the present invention.

FIG. 70 is a flowchart of Example 21 of the present invention.

[Explanation of symbols]

1 .. Photosensitive drum 2 .. Primary charger 3 .. Scanning optical device 4 .. Development device 5 .. Cleaning device 6 .. Conveyor belt 7 .. Transfer charger 8 .. Fixing device 10 .. Drive motor 11.・ Surface potential detector 12 ・
・ Test pattern reading device 14 ・ ・ Surface potential detector 16 ・ ・ Concentration conversion circuit 22 ・ ・ Test pattern
24..Transfer material discharge port 26..Image processing circuit 27 ..
・ Timing control means 30 ・ ・ Copier body 31 ・ ・
Color original 33 .. Color image sensor 35 ..
Color signal processing circuit 51 ... Conveying belt support member 5
2 ... Suction box 53 ... Exhaust fan 54 ... Opening 5
5 ・ ・ Upper support roller 56 ・ ・ Lower support roller 59 ・
・ Pressing mylar 60 ・ ・ Transfer material conveying device 67 ・ ・
ITOP sensor 76..Belt shake correction motor 7
7 ... Infrared light emitting element 78 ... Infrared light receiving sensor 7
9 ... Mark 81 ... Sensor detection point 84 ... Memory 85 ... Triangular wave 90 ... Cleaning means 91 ... Frame
92..Fur brush 94..Conductive brush 100
..Controller 101 .. Reader unit 102 .. Printer unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03G 15/01 114 B 15/16 // G01N 21/47 F 7370-2J (72) Inventor Fujita Gaku Tokyo 3-30-2 Shimomaruko, Ota-ku, Canon Inc. (72) Inventor Yoshihiro Murasawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masami Izumizaki Tokyo 3-30-2 Shimomaruko, Ota-ku Canon Inc. (72) Inventor Koji Amamiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Nobutatsu Sasanamu 3 Shimomaruko Ota-ku, Tokyo Chome 30-2 Canon Inc.

Claims (19)

[Claims] 1. A test pattern for registration correction on a transfer material conveying belt or for correction of image forming means is read by a reading device and transferred using a plurality of image forming means for forming a target image. In an image forming apparatus having a means for multiple recording on a material and a means for detecting the density of the test pattern on the conveyor belt, the conveyor belt of the transfer material conveyor is stably supported near the position where the test pattern is read. An image forming apparatus comprising: a conveyor belt supporting unit that operates. 2. The image forming apparatus according to claim 1, wherein the conveyor belt support means includes a conveyor belt support member that is in contact with the conveyor belt, a conveyor belt, and a suction means that attracts the conveyor belt support member. 3. The image forming apparatus according to claim 1, wherein the conveyor belt supporting unit has an upper supporting member and a lower supporting member provided at upper and lower portions of the conveyor belt. 4. The upper and lower support members contact the conveyor belt,
The image forming apparatus according to claim 3, wherein the image forming apparatus is detachable. 5. The image forming apparatus according to claim 4, wherein the upper and lower support members are brought into and out of contact with the conveyor belt according to whether or not a test pattern is formed. 6. The transfer material is transferred onto a transfer material using an image forming means for reading a test pattern for registration correction on the transfer material conveying belt or for correcting an image forming means with a reading device and forming a target image. An image forming apparatus having means for transferring the test pattern onto the transfer belt and a means for detecting the density of the test pattern on the transfer belt, the test pattern reading device illuminating the test pattern on the transfer material transfer belt; A reading sensor for reading the test pattern image by projecting the reflected light of the test pattern illuminated by the image forming lens, and the illuminating device is provided in a plane projected on the transfer material transport belt in the moving direction of the transfer material transport belt. An image forming apparatus having an angle of 60 degrees or less. 7. An image formation capable of forming images of a plurality of colors by juxtaposing a plurality of image carriers and sequentially transferring images formed on the respective image carriers onto a transfer material conveyed by a conveyor belt. In the image forming apparatus, an image forming apparatus is characterized in that a deviation state of the conveyance belt is detected by a conveyance belt on which a mark is written and a means for reading the mark. 8. An image forming method in which a plurality of image carriers are juxtaposed and images formed on the respective image carriers are sequentially transferred onto a transfer material conveyed by a conveyor belt to form images of a plurality of colors. In the device, means for detecting the deviation state of the conveyor belt,
A means for correcting the deviation of the conveyor belt is provided, and the means for correcting the deviation of the conveyor belt is controlled by the signal detected by the means for detecting the deviation of the conveyor belt to reduce the deviation amount of the conveyor belt. An image forming apparatus characterized by: 9. A transfer pattern on a transfer material is read by a plurality of image forming means for forming a target image by reading a test pattern for registration correction on a conveyor belt or for correcting image forming means with a reading device. An image forming apparatus having means for transferring to an image forming apparatus, characterized in that the image forming apparatus has a conveyor belt having an absorptance for infrared light higher than a transmissivity. 10. The image forming apparatus according to claim 9, wherein the conveyor belt is made of a resin in which carbon is kneaded. 11. A transfer pattern on a transfer material is read by a plurality of image forming means for forming a target image by reading a test pattern for registration correction on a conveyor belt or for correcting image forming means with a reading device. In the image forming apparatus having a means for multiple recording on the transfer material and a means for detecting the density of the test pattern on the transfer material, the spectral reflection characteristics of the developer in the image forming portion serving as a reference of the resist are It has no sensitivity and is sensitive to the spectral reflection characteristics of other color developers, and the test pattern of the reference image forming section is superimposed on the test pattern of the image forming section whose registration is to be read. An image forming apparatus which detects a resist amount by reading a combined test pattern. 12. A pattern forming means for forming a predetermined test pattern on an image carrier, a pattern on the image carrier formed by the pattern forming means, or a conveyor belt for carrying a transfer material, or an intermediate part. And a reflected light amount detecting means for detecting the reflected light amount of the test pattern on the transfer material carrier in a minute area, and the image formation of the image forming apparatus by the reflected light amount movement pattern information detected by the reflected light amount detecting means. An image forming apparatus which detects a state, continuously changes an image forming condition and continuously detects the image forming state, and obtains an optimum value of the image forming condition based on a detection result. 13. The image forming apparatus according to claim 12, wherein the means for detecting the image forming condition is a spatial transfer function MTF. 14. The image forming condition is at least one of a transfer current, which is a transfer condition, a contact pressure of a transfer assisting device, and a difference in peripheral speed between a photosensitive member and a transfer material conveying device. The image forming apparatus according to claim 12. 15. The reflected light amount detecting means is 30 μm × 3
The image forming apparatus according to claim 11, wherein the amount of reflected light in a minute area of 0 μm or less can be read. 16. An image forming unit having an image carrier on which a visible image is formed, and an image forming unit adjacent to the image carrier, the transfer material is fixed by electrostatic attraction and conveyed, and the visible image is transferred. A transfer device having a transfer material transfer belt that passes through the position and a cleaning unit that cleans the transfer belt are provided, and a charge removal unit is provided upstream of the image forming unit and downstream of the cleaning unit with respect to the moving direction of the transfer belt. An image forming apparatus characterized by the above. 17. The image forming apparatus according to claim 16, wherein the cleaning unit operates during image formation. 18. The image forming apparatus according to claim 16, wherein after the image formation is completed, the discharging unit ends the operation after the conveyance belt is stopped. 19. The transfer device is provided with an endless flexible belt as a transfer material transfer belt.
The image forming apparatus according to item 1.