JP2006189798A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a blade from wearing when the normally separated blade comes in contact with the image carrier. <P>SOLUTION: This image forming device has an image carrier 21, a toner image forming means 19 to form a toner image on the above-image carrier 21, a transfer means 22 to transfer the above toner image on the image carrier 21 to a transfer material P, a blade 51 which comes in contact with or moves apart from the image carrier 21 to remove the toner remaining on the image carrier 21 being not transferred to the above transfer material P, and a contact control means 80 to form a transfer toner image on the image carrier 21 and to bring the separated blade 51 in contact with the transfer toner image. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus for forming an image by transferring a toner image formed on an image carrier onto a transfer material, and in particular, image formation for removing toner remaining on the image carrier after transfer with a blade member. Relates to the device.

  With the recent colorization of image forming apparatuses, image forming apparatuses in which an image carrier rotates a plurality of times during image formation are frequently used.

  In this type of image forming apparatus, the cleaning member for removing the toner on the image carrier is in contact with and separated from the image carrier. As the cleaning member, a blade member is used because of its simple configuration.

JP 2000-231274 A

  By the way, in order to prevent the blade member from being worn during the toner removal, it is necessary that the toner adheres appropriately on the ridge line (edge) of the blade. While the toner is being removed, a part of the toner to be removed remains on the ridgeline and wear is prevented.

  However, there is a case where the toner is separated from the edge due to vibration accompanying the separation operation of the blade member. Then, the edge contacts the image carrier in a state where there is not enough toner between the edge and the image carrier.

  Here, when the separated blade member comes into contact with the image carrier, there is a problem that the blade member is worn.

  An object of the present invention is to prevent the blade member from being worn when the blade member in the separated state contacts the image carrier.

  To achieve the above object, a typical configuration of the present invention includes an image carrier, toner image forming means for forming a toner image on the image carrier, and a transfer material for transferring the toner image on the image carrier. A transfer member that transfers to the image carrier, a blade member that contacts and separates from the image carrier and removes transfer residual toner that remains on the image carrier without being transferred to the transfer material, and abuts on the image carrier A contact control means for forming a toner image and contacting the separated blade member with the contact toner image.

  According to the present invention, by bringing the blade member into contact with the toner image for contact, the blade member is in contact with the image carrier in a state where sufficient toner exists between the blade member and the image carrier, and the blade member Abrasion can be prevented.

  Examples of the present invention will be described in detail below.

{First Example}
A first embodiment of an image forming apparatus according to the present invention will be described. FIG. 1 is a schematic diagram of an image forming apparatus according to the first embodiment. FIG. 2 is a diagram illustrating the configuration of the cleaning device. FIG. 3 is a diagram for explaining the toner image on the intermediate transfer belt and the blade separation position.

  The image forming apparatus shown in FIG. 1 is an intermediate transfer type color image forming apparatus including one photosensitive drum and one intermediate transfer member (image carrier). A photosensitive drum 17 as an example of an image carrier is uniformly charged by a charger 18 and then irradiated with laser light 13 from a light source 11 based on color information of each color from a polygon mirror 14 to a lens 15 and a mirror. 16 and the latent image for each color is exposed.

  Here, the color information of each color is formed by the CPU 70 based on electronic data relating to image information sent from the document reading device 60 and a personal computer connected to the image forming device.

  The document placed on the document tray 62a of the document reading device 60 is sent to the platen 61e, and the entire surface is scanned by the first mirror unit 61a. The document whose image has been read is discharged to the discharge tray 62b. The image scanned by the first mirror unit 61a is guided to the CCD 62 via the second mirror unit 61b and the lens 61c, where it is converted into electronic data and sent to the CPU 70.

  Further, the document reading device 60 and the PC simultaneously send information about the transfer material P used for image formation to the CPU 70 together with the image information.

  The rotary developing device 19 forms a toner image by developing the latent image on the photosensitive drum 17 by developing devices (toner image forming means) 19Y, 19M, 19C, and 19K for each of yellow, magenta, cyan, and black. To do. The formed toner images of respective colors are transferred to an intermediate transfer belt 21 as an example of an intermediate transfer member by a primary transfer roller 22. The primary transfer residual toner remaining on the photosensitive drum 17 rotating in the direction of the arrow R2 is removed by the drum cleaner 20, so that the photosensitive drum 17 is used for the next image formation.

  The intermediate transfer belt 21 is stretched by a driving roller 23, a tension roller 24, and a driven roller 25. When the driving roller 23 is rotated by the motor 231, the intermediate transfer belt 21 rotates at a speed synchronized with the peripheral speed of the photosensitive drum 17. The intermediate transfer belt 21 is a film-like belt in which an appropriate amount of a conductive agent such as carbon black is dispersed in a synthetic resin such as polyimide, polycarbonate, polyester, or polypropylene, or various rubbers, and the thickness is set to 0.1 mm, for example. Is formed by. The circumferential length of the intermediate transfer belt 21 is set to an integral multiple (for example, 3 times) of the circumferential length of the photosensitive drum 17.

  While the intermediate transfer belt 21 rotates a plurality of times, the primary transfer roller 22 primarily transfers the toner images of the respective colors in a superimposed manner, and carries the color toner images. When the color toner image is formed, the secondary transfer roller (transfer member) 27 separated from the driven roller 25 comes into contact with the intermediate transfer belt 21, and the secondary transfer roller 27 is moved in the secondary transfer area A. Secondary transfer is performed collectively on the transfer material P. The secondary transfer roller 27 is disposed so as to be detachable from the intermediate transfer belt 21 as necessary. When a color image is formed, the unfixed toner image of the final color is transferred onto the intermediate transfer belt 21. Until it is primarily transferred to the intermediate transfer belt 21.

  The transfer material P is accommodated in feeding cassettes 26a and 26b below the apparatus, and is separated and fed one by one by pickup rollers 28a and 28b and separation feeding roller pairs 29a and 29b. Is conveyed to the secondary transfer section. The transfer material P onto which the toner image has been transferred is melted and fixed by applying heat and pressure by the fixing roller pair 32 and then discharged outside the apparatus by the discharge roller pair 33.

  By the way, in this embodiment, a cleaning device 50 is provided as an example of a cleaning unit that removes adhering matter such as residual toner and paper dust attached to the surface of the intermediate transfer belt 21. The cleaning device 50 is disposed on the upstream side of the photosensitive drum 17 in the driving rotation direction of the intermediate transfer belt 21.

  FIG. 2 is an enlarged main part configuration diagram for explaining the vicinity of the cleaning device. The cleaning device 50 includes a cleaning blade (blade member) 51 that removes deposits on the surface of the intermediate transfer belt 21, a storage portion 57 that stores deposits such as residual toner and paper dust removed by the cleaning blade 51, and a storage portion 57. An auger 58 for conveying the residual toner and the like inside the cleaning device 50 is provided.

  The cleaning blade 51 is made of an elastic material and presses against the surface of the intermediate transfer belt 21 that moves at a speed of 140 mm / sec to remove deposits on the surface of the intermediate transfer belt 21. Examples of the material of the cleaning blade 51 include a 2 mm thick plate material made of polyurethane, but the thickness and material of the blade 51 are not limited thereto.

  The cleaning blade 51 of the cleaning device 50 normally stands by at a position separated from the intermediate transfer belt 21 until the final toner image is transferred onto the intermediate transfer belt 21. The transferred toner image is not disturbed. Then, after the final toner image is transferred onto the intermediate transfer belt 21, the cleaning blade 51 is pressed against the surface of the intermediate transfer belt 21 to perform cleaning.

  As shown in FIG. 2A, the cleaning blade 51 is fixed to a sheet metal 52 by means such as adhesion, and the sheet metal 52 is attached to a metal pressing plate 53 by means such as welding or bolting. The pressing plate 53 is rotatable about a fulcrum 54, and an eccentric cam 56 is in contact with the fulcrum 54 on the side opposite to the sheet metal 52. Note that the pressing plate 53 is urged in a direction in pressure contact with the eccentric cam 56, that is, in a clockwise direction by a spring or the like (not shown).

  Then, the cleaning device 50 rotates the eccentric cam 56 by a predetermined amount at a predetermined speed by a drive motor and a drive gear (not shown), and moves the pressing plate 53 in the clockwise direction shown in the drawing by the eccentric cam 56 to thereby press the As shown in FIG. 2B, the cleaning blade 51 attached to the plate 53 via the sheet metal 52 is configured to be brought into pressure contact with the surface of the intermediate transfer belt 21. Further, the cleaning device 50 rotates the eccentric cam 56 by a predetermined amount at a predetermined speed by a driving motor and a driving gear (not shown), and moves the pressing portion 55 of the pressing plate 53 in the counterclockwise direction by the eccentric cam 56. Thus, the cleaning blade 51 attached to the pressing plate 53 via the sheet metal 52 is configured to be separated from the surface of the intermediate transfer belt 21 as shown in FIG. As described above, the cleaning blade 51 is attached to the intermediate transfer belt 21 so as to advance (contact) and retract (separate) by rotating the eccentric cam 56.

  The accommodating portion 57 of the cleaning device 50 may be configured to move to the intermediate transfer belt 21 side with the operation of the cleaning blade 51 being pressed against the intermediate transfer belt 21.

  As shown in FIG. 2A, the cleaning blade 51 has its tip end pressed against the upstream side in the movement direction of the intermediate transfer belt 21 and the rear end side of the blade 51 on the downstream side in the movement direction of the intermediate transfer belt 21. And the rear end side of the blade 51 is inclined with respect to the surface of the intermediate transfer belt 21. Since the cleaning blade 51 is made of an elastic material such as polyurethane, when it is brought into pressure contact with the surface of the intermediate transfer belt 21 by a predetermined amount, the tip of the cleaning blade 51 is the surface of the intermediate transfer belt 21 as shown in FIG. In a state where it is in pressure contact, it is curved to curve downward.

  In this embodiment, as described above, the cleaning blade 51 is a polyurethane blade. As shown in FIG. 2B, the blade 51 has a thickness t = 2 mm, a width W = 15 mm, and a free blade. The length L is 10 mm, the length is formed to be substantially the entire width of the intermediate transfer belt 21, the setting angle (hereinafter referred to as “SA”) is 17 °, and the amount of biting into the intermediate transfer belt 21 (hereinafter referred to as “nip amount”). ) Is set to 1.1 mm. However, the SA and nip amount of the cleaning blade 51 may be set to other values as appropriate.

  Next, the operation of the cleaning device 50 that is a feature of this embodiment will be described. FIG. 3 is a diagram illustrating the contact and separation positions of the toner image on the intermediate transfer belt and the cleaning blade. As shown in the drawing, in this embodiment, two images are formed on the intermediate transfer belt 21 while the belt makes one revolution.

  First, conventional control will be described with reference to FIG. The blade contact position T1 is set before the head of the Nth secondary transfer residual toner Zn passes, and the cleaning blade 51 is brought into contact with the intermediate transfer belt 21. After the secondary transfer toner Zn passes, the separation position T2 is set, and the cleaning blade 51 is separated from the intermediate transfer belt 21. Then, two (N + 1) th images are formed while rotating the intermediate transfer belt 21 a plurality of times, and the blade contact position T1 is set before the head of the (N + 1) th secondary transfer residual toner Zn + 1 passes.

  By the way, in this embodiment, a part of the secondary transfer residual toner on the surface of the intermediate transfer belt 21 is left without being removed.

  Then, when the cleaning blade 51 is contacted next time, control is performed so as to contact the remaining transfer residual toner. The above control is performed by the contact control means 80 (see FIG. 1). This control is not performed every time cleaning is performed by the cleaning device 50, but is performed every predetermined number of times (N times) of image formation as necessary.

  In this embodiment, when an image having an image ratio (ratio of the area of the image formed area to the entire area of the image formable area) of 5% is continuously printed, one secondary transfer residual toner is printed every 100 sheets. The cleaning blade 51 in a separated state is brought into contact with the remaining secondary transfer residual toner. Further, when continuously printing an image with an image ratio of 3%, a part of the secondary transfer residual toner is left without being removed every 200 sheets, and the remaining secondary transfer residual toner is separated. The cleaning blade 51 is brought into contact.

  For example, as shown in FIG. 3B, the blade contact position T1 is set after the head of the Nth secondary transfer residual toner Zn has passed.

  Hereinafter, during continuous printing, a part of the secondary transfer residual toner on the surface of the intermediate transfer belt 21 is left without being removed, and the separated cleaning blade 51 is brought into contact with the residual secondary transfer residual toner. The method is described.

  The separation position T2 is set after the secondary transfer residual toner Zn has passed. As a result, the leading portion of the secondary transfer residual toner Zn remains on the intermediate transfer belt 21 (hereinafter referred to as “removed residual toner Zn ′”). At this time, it is determined at which position on the intermediate transfer belt 21 the secondary transfer residual toner remains from the contact start timing of the cleaning blade 51 and the driving time of the motor 231 measured by the timer 232 (see FIG. 1). Store it in the main body.

  Next, image formation is started so that the toner image on the (N + 1) th photosensitive drum 17 does not overlap with the removal residual toner Zn ′ left in the previous cleaning, and primary transfer is performed on the intermediate transfer belt 21. Immediately after the removal residual toner Zn ′ passes through the secondary transfer portion, the secondary transfer roller 27 is brought into contact with the surface of the intermediate transfer belt 21, and a bias is applied to the secondary transfer roller 27, so that the (N + 1) th toner image is obtained. Zn + 1 is secondarily transferred onto the transfer material.

  When cleaning the (N + 1) th secondary transfer residual toner Zn + 1, the blade contact position T1 is set in the area of the removal residual toner Zn '. The separation position T2 is set after the secondary transfer residual toner Zn + 1 has passed.

  The secondary transfer residual toner of the last toner image at the time of continuous printing is always left on the intermediate transfer belt 21 without being partially removed regardless of the number of continuous prints. When only one sheet is formed, a part of the secondary transfer residual toner of the image is left without being removed.

  When the image forming apparatus is in a stopped state without image formation, the cleaning blade 51 is separated from the intermediate transfer belt 21.

  When image formation is started, the cleaning blade 51 contacts the intermediate transfer belt 21 and cleans the entire circumference of the intermediate transfer belt 21 before a latent image based on color information is formed on the photosensitive drum 17. . At this time, the cleaning blade 51 comes into contact with the secondary transfer residual toner that is left without being removed when the previous print job is executed.

  By performing the above-described control, it is possible to reliably supply toner having a small particle size that serves as a lubricant between the cleaning blade 51 and the intermediate transfer belt 21. In addition, it has been confirmed by experiments that the amount of torque of the intermediate transfer belt 21 has decreased, and it can be inferred that the frictional force has decreased. In addition, an endurance test is actually performed to confirm that the durability of the cleaning blade 51 is improved.

  In this embodiment, the removal residual toner Zn ′ is made by leaving the head portion of the secondary transfer residual toner Zn, but it may be controlled to leave the rear end portion of the secondary transfer residual toner Zn.

  That is, according to the configuration of this embodiment, it is possible to improve the durability of the cleaning blade while using the secondary transfer residual toner to suppress excessive toner consumption.

{Second Example}
A second embodiment of the image forming apparatus according to the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The present embodiment is based on the control of the first embodiment, and further changes the timing (frequency) for executing the control according to the type of transfer material.

  When continuous printing is performed by mixing the B5 size and the A4 size, the toner (secondary transfer residual toner Zn) provided to the cleaning blade 51 is inevitably reduced. For this reason, the frictional force between the intermediate transfer belt 21 and the cleaning blade 51 increases, and at the same time, the torque increase rate of the intermediate transfer belt 21 increases. Therefore, in such a case, the contact control means 80 performs the control described in the first embodiment with a shorter cycle than usual (when only an A4 size transfer material is used) (the N is reduced). ). In this case, a part of the secondary transfer residual toner of the toner image using the A4 size transfer material is not removed but left on the intermediate transfer belt 21, and the cleaning blade 51 is placed on the remaining secondary transfer residual toner. Abut. As a result, the benefits of the present invention can be effectively obtained even when printing is performed by mixing small-size transfer materials.

{Third embodiment}
A third embodiment of the image forming apparatus according to the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

In the configuration using the thermal fixing unit as in this embodiment, it is necessary to reduce the conveyance speed of the transfer material when passing through the fixing unit in continuous image formation such as OHT or thick paper. For this purpose, control is performed such that the speed of the intermediate transfer belt 21 is temporarily reduced according to the fixing property and then returned to the normal speed again. The change of the speed of the intermediate transfer belt 21 is executed when the motor transmission (moving speed changing means) 233 changes the rotation speed of the motor 231. When paper having a normal thickness (80 g / m ² ) is used, the intermediate transfer belt 21 moves at a constant speed of 140 mm / sec. On the other hand, when OHT or thick paper (130 g / m ² ) is used, the speed of the intermediate transfer belt 21 during the primary transfer is 140 mm / sec, but the speed of the intermediate transfer belt 21 during the secondary transfer. Is changed to 70 mm / sec. That is, the removal of the secondary transfer residual toner is performed in a state where the speed of the intermediate transfer belt 21 is 70 mm / sec. In such control, the speed of the intermediate transfer belt 21 is changed while the cleaning blade 51 is in contact with the surface of the intermediate transfer belt 21. For this reason, the load on the cleaning blade 51 is increased by the change in the frictional force between the surface of the intermediate transfer belt 21 and the cleaning blade 51.

  In this embodiment, therefore, the control described in the first embodiment is performed in a short cycle (the N is reduced) even when an image is continuously formed on a transfer material that is fixed slowly such as OHT or cardboard. In this embodiment, when the normal thickness paper is used continuously, the control shown in the first embodiment is performed for every 200 sheets of transfer material, but when OHT or thick paper is used continuously. The control shown in the first embodiment is performed for every 100 transfer materials. That is, the frequency of the control is changed according to the speed of the intermediate transfer belt 21 when the secondary transfer residual toner on the intermediate transfer belt 21 is removed.

  Thus, even when the transfer material is used and the speed of the intermediate transfer belt 21 when the secondary transfer residual toner is removed changes, the benefits of the present invention can be effectively obtained.

{Fourth embodiment}
A fourth embodiment of the image forming apparatus according to the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The present embodiment is based on the control of the first embodiment, and further changes the timing (frequency) of executing the control according to the environmental conditions.

  When the cleaning blade 51 is used as a cleaning unit as in the present embodiment, the strain on the cleaning blade 51 increases due to a change in the hardness of the cleaning blade 51 in a high humidity environment, thereby increasing the load on the cleaning blade 51. Further, as the amount of water (mass of water contained in 1 kg of air) increases, the nip area formed by the surface of the intermediate transfer belt 21 and the cleaning blade 51 increases, so the frictional force also increases. In addition, discharge products are generated on the surface of the intermediate transfer belt 21 due to the discharge for primary transfer and secondary transfer, so that filming and fusion occur on the intermediate transfer belt 21, and the intermediate transfer belt 21 The coefficient of friction of the surface is increased.

  On the other hand, in the low temperature and low humidity environment, in the configuration as in this embodiment, the peeling discharge phenomenon occurs in the primary transfer and the secondary transfer. Of course, it can be said that normally, there is almost no influence on the toner image to be formed, but the accumulation of damage to the surface of the intermediate transfer belt 21 during durability is large, and the surface of the intermediate transfer belt 21 is about 10,000 sheets. The friction coefficient has changed greatly.

  As described above, under a high-temperature and high-humidity environment or a low-temperature and low-humidity environment, the load on the cleaning blade 51 may be greater than that under a normal temperature and normal humidity environment due to changes in properties of the cleaning blade 51 and changes in the surface of the intermediate transfer belt 21. Is also much larger.

  Therefore, in this embodiment, the control described in the first embodiment is performed in a short cycle under a high temperature and high humidity environment or a low temperature and low humidity environment (N is reduced).

  The environmental sensor (detection means) 90 detects the temperature and humidity in the vicinity of the cleaning blade 51 and calculates the amount of air moisture. Then, the frequency of control is changed by the contact control means 80 in accordance with the amount of moisture.

  In the present embodiment, when the amount of water is more than 0 g and less than 2.0 g (low temperature and low humidity environment), each time image formation is performed on 100 A4 size transfer materials, Control is performed.

  When the water content is 2.0 g or more and less than 8.7 g (normal temperature and normal humidity environment), the control of the first embodiment is performed every time image formation is performed on 200 A4 size transfer materials. Is done.

  When the water content is 8.74 g or more and 21.0 g or less (high temperature and high humidity), the control of the first embodiment is performed every time image formation is performed on 100 A4 size transfer materials. .

  Accordingly, the benefits of the present invention can be effectively obtained even under such environmental conditions.

{Fifth embodiment}
A fifth embodiment of the image forming apparatus according to the present invention will be described.

  In this embodiment, the toner image formed on the photosensitive drum 17 is transferred to the intermediate transfer belt 21 to form a toner image on the intermediate transfer belt 21. Then, the cleaning blade 51 in a separated state is brought into contact with the toner image.

  The present embodiment will be described with reference to FIG. In addition, about the part which overlaps with said 1st Example, the same number is attached | subjected and description is abbreviate | omitted.

  The latent image formed on the photosensitive drum 17 based on the color information of the first color yellow is developed by the yellow developing device 19Y to form a yellow toner image. The yellow toner image is transferred to the intermediate transfer belt 21 by the primary transfer roller 22. Subsequently, toner images of the second color magenta and the third color cyan are also formed on the photosensitive drum 17 based on the color information, and transferred so as to overlap the yellow toner image on the intermediate transfer belt 21.

  Then, prior to the formation of the latent image based on the black color information of the fourth color of the final color, a latent image of a toner image that contacts the cleaning blade 51 (hereinafter referred to as “contact toner image”) is formed on the photosensitive drum 17. The The size of the latent image of the contact toner image was the maximum value of the width in which the toner image can be formed in the longitudinal direction (axial direction of the photosensitive drum), and the moving direction was about 10 mm. The latent image of the contact toner image and the latent image based on the black color information are developed by the black developing device 19K.

  The distance between the contact toner image and the toner image formed based on each color information in the moving direction of the intermediate transfer belt 21 is about 30 mm.

  The toner image formed based on the contact toner image and the color information moves to the secondary transfer area A. When the contact toner image passes through the secondary transfer area A, the secondary transfer roller 27 is moved to the intermediate transfer belt. 27, and is secondarily transferred onto the transfer material P all at once. On the other hand, the cleaning blade 51 that is in a separated state while the yellow, magenta, cyan, and black toner images are primarily transferred is controlled to contact the contact toner image.

  FIG. 4 shows the toner image for contact on the intermediate transfer belt 21, the secondary transfer residual toner of the toner image formed based on the color information, the contact position T1 and the separation position T2 of the cleaning blade 51. R1 in the figure is the rotation direction of the intermediate transfer belt 21.

  As described above, it is also possible to prevent the cleaning blade 51 from being worn by bringing the cleaning blade 51 into contact with the formed contact toner image.

  In addition, the contact toner image can be formed with yellow for the first color, magenta for the second color, and cyan for the third color.

  Also in this embodiment, when images with an image ratio of 5% are continuously printed, a contact toner image is formed every 100 sheets, and the separated cleaning blade 51 is applied to the contact toner image. Make contact. When an image with an image ratio of 3% is continuously printed, a contact toner image is formed every 200 sheets, and the separated cleaning blade 51 is contacted on the contact toner image.

{Sixth embodiment}
A sixth embodiment of the image forming apparatus according to the present invention will be described.

  The present embodiment is based on the fifth embodiment, and further changes the timing (frequency) of executing the control according to the type of transfer material.

  When image formation is continuously performed on a transfer material having a small size such as B5, the toner (secondary transfer residual toner Zn) provided to the cleaning blade 51 is inevitably reduced. Particularly, since the toner is not supplied to the end portion of the blade, the increase in load is remarkable.

  Therefore, the control described in the fifth embodiment is performed at a shorter cycle than usual (when an A4-size transfer material is used) (N is reduced). In this embodiment, when an image is formed on a B5 size transfer material, the control of the fifth embodiment is performed for every 50 transfer materials.

{Seventh embodiment}
In this embodiment, the frequency of performing the control of the fifth embodiment is changed according to the speed of the intermediate transfer belt 21.

  Also in this embodiment, as shown in the third embodiment, when using OHT or thick paper, the speed of the intermediate transfer belt 21 is decreased according to the fixing property.

  That is, when a normal thickness paper is used, the intermediate transfer belt 21 moves at a constant speed of 150 mm / sec. On the other hand, when OHT or thick paper is used, the speed of the intermediate transfer belt 21 at the time of secondary transfer is changed to 75 mm / sec, and the secondary transfer residual toner is removed while the speed of the intermediate transfer belt 21 is 75 mm / sec. Done.

  In this embodiment, when the normal thickness paper is used continuously, the control shown in the fifth embodiment is performed for every 200 transfer materials, but when OHT or thick paper is used continuously. Performs the control shown in the fifth embodiment every 100 sheets.

  In addition, the frequency of execution of the control of the fifth embodiment can be changed according to the environment in the image forming apparatus. The environmental sensor 90 detects the temperature and humidity in the vicinity of the cleaning blade 21 and calculates the mass (water content) of water contained in 1 kg of air.

  In this embodiment, when the water content is 8.74 g (normal temperature and normal humidity environment), the control of the fifth embodiment is performed every time image formation is performed on 200 A4 size transfer materials.

  When the water content is 21.0 g (high temperature and high humidity), the control of the fifth embodiment is performed every time image formation is performed on 100 A4 size transfer materials.

1 is a schematic diagram of an image forming apparatus according to a first embodiment. It is a figure explaining the structure of a cleaning apparatus. FIG. 6 is a diagram for explaining secondary transfer residual toner on an intermediate transfer belt and a blade separation position. FIG. 6 is a diagram illustrating a contact toner image on an intermediate transfer belt and a blade contact / separation position.

Explanation of symbols

A ... secondary transfer region P ... transfer material Zn ... secondary transfer residual toner Zn '... removed residual toner 11 ... light source 13 ... laser beam 14 ... polygon mirror 15 ... lens 16 ... mirror 17 ... photosensitive drum 18 ... charger 19 ... Developers 19Y to 19K ... Developer (toner image forming means)
20 ... drum cleaner 21 ... intermediate transfer belt (image carrier)
22 ... primary transfer roller 23 ... driving roller 24 ... tension roller 25 ... driven roller 26 ... feeding cassette 27 ... secondary transfer roller (transfer member)
28 ... Pick-up roller 29 ... Separation feeding roller pair 30 ... Conveying roller 31 ... Registration roller pair 32 ... Fixing roller pair 33 ... Discharge roller pair 50 ... Cleaning device 51 ... Cleaning blade (blade member)
52 ... Sheet metal 53 ... Pressing plate 54 ... Support point 56 ... Eccentric cam 57 ... Housing portion 58 ... Auger 70 ... CPU
80 ... Contact control means 90 ... Environmental sensor (detection means)
231 ... Motor 232 ... Timer 233 ... Motor transmission (moving speed changing means)

Claims (9)

An image carrier;
Toner image forming means for forming a toner image on the image carrier;
A transfer member for transferring the toner image on the image carrier to a transfer material;
A blade member that contacts and separates from the image carrier and removes transfer residual toner remaining on the image carrier without being transferred to the transfer material;
A contact control means for forming a contact toner image on the image carrier and contacting the separated blade member with the contact toner image;
An image forming apparatus comprising: The toner image forming means forms the toner image in a toner image forming region of the image carrier;
2. The contact toner image forming apparatus according to claim 1, wherein the contact control unit forms the contact toner image by causing the blade member to perform at least one of contact and separation in the toner image forming region. The image forming apparatus described in 1.   Means for changing the frequency of contact of the blade member in the separated state with the contact toner image according to the length of the transfer material in a direction orthogonal to the moving direction of the image carrier. The image forming apparatus according to claim 2. Detecting means for detecting environmental conditions in the image forming apparatus;
Means for changing the frequency of contact of the blade member in the separated state with the contact toner image based on a detection result of the detection means;
The image forming apparatus according to claim 3, further comprising: Moving speed changing means for changing the moving speed of the image carrier;
Means for changing the frequency of contact of the blade member in the separated state with the contact toner image according to the moving speed while the blade member is in contact with the image carrier;
The image forming apparatus according to claim 4, further comprising: The transfer member transfers the toner image to the transfer material in a transfer region,
The contact control unit forms the contact toner image by passing the toner image formed on the image carrier by the toner image forming unit through the transfer region where the transfer material is not present. The image forming apparatus according to claim 1.   A means for changing a frequency of contact of the blade member with the contact toner image according to a length of the transfer material in a direction orthogonal to a moving direction of the image carrier. Item 7. The image forming apparatus according to Item 6. Detecting means for detecting environmental conditions in the image forming apparatus;
Means for changing the frequency of contact of the blade member with the contact toner image based on a detection result of the detection means;
The image forming apparatus according to claim 1, further comprising: Moving speed changing means for changing the moving speed of the image carrier;
Means for changing the frequency of contact of the blade member with the contact toner image in accordance with the moving speed while the blade member is in contact with the image carrier;
The image forming apparatus according to claim 1, further comprising:

Images