JP2014026029A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition capable of varying loudness of contact sound while not deteriorating productivity of image formation without a special additional mechanism in an image forming apparatus capable of having a transfer means make contact/separate from an image carrier.SOLUTION: The image forming apparatus includes: an image carrier for carrying a toner image; transfer means for transferring the toner image on the image carrier; a contacting/separating mechanism for abutting/separating the image carrier and the transfer means; first driving means for driving the contact/separating mechanisms; second driving means for driving other members which are other than the contact/separating mechanism; and control means for controlling these driving means independently from each other. In this case, the first driving means is controlled so that the first abutting speed for having the contacting/separating mechanism abut the image carrier and the transfer means when the second driving member is not driving the other members is slower than the second abutting speed for having the contacting/separating mechanism abut the image carrier and the transfer means when the second driving means is driving the other members.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and the like, and in particular, an image having a function of contacting and separating a transfer nip forming member that forms a transfer nip by contacting an image carrier. The present invention relates to a forming apparatus.

  For example, a conventional intermediate transfer type image forming apparatus includes a photosensitive drum on which a toner image corresponding to an electrostatic latent image is formed, and a belt-like shape on which the toner image on the photosensitive drum is to be transferred intermediately. An intermediate transfer member, a primary transfer device that transfers a toner image on the photosensitive drum to the intermediate transfer member, and a toner image transferred onto the intermediate transfer member are collectively transferred to a sheet as a recording medium. A device including a secondary transfer device is known.

  In the secondary transfer device, the purpose of preventing contamination when the toner density adjustment pattern is drawn on the intermediate transfer member, or the intermediate transfer member is prevented from being plastically deformed due to the contact of the secondary transfer means when left for a long period of time. For this purpose, a configuration having a mechanism for separating the secondary transfer unit from the intermediate transfer member is often used. For the purpose of accurately separating the secondary transfer unit from the intermediate transfer member, for example, a contact provided on the same axis as the secondary transfer counter roller in the intermediate transfer unit including the intermediate transfer member and a plurality of rollers around which the intermediate transfer member is wound. Methods have been devised in which the secondary transfer means is brought into contact with and separated from by a separation cam (contacting / separating means) (Patent Documents 1 and 2).

  When the secondary transfer device adopts such a contact / separation method and the intermediate transfer unit is detachable from the main body, the positional relationship between the secondary transfer contact / separation cam and the secondary transfer means is achieved by detaching the unit. Therefore, after the intermediate transfer unit is set in the apparatus main body, it is necessary to perform an initialization operation (initial setting operation) for executing secondary transfer contact / separation to move the secondary transfer unit to a certain position. is there.

  The so-called return operation such as the initializing operation stopped when the machine power was turned on at the time of long-term span power off, power outage, maintenance processing, delivery as a new product, or normal operation was not completed due to jamming etc. It is necessary in some cases. When stopping due to a jam, etc., the position of the contact / separation cam can be grasped, so there is no need to detect the position by rotating the cam once, and it is sufficient to return to the initial state, but the machine power is turned off. If it is detected that it is an unintended position such as a position not in time for the first copy time, the secondary transfer means is moved to a predetermined position. In order to move to a certain position, an initialization operation must be performed.

  In general, the position of the contact / separation cam, that is, its phase, is detected by recognizing the end of a light-shielding portion (filler) attached to the cam using an optical sensor. FIG. 6 illustrates the relationship between the contact / separation of the intermediate transfer member and the secondary transfer unit and the phase of the contact / separation cam. In this method, the cam is rotated for a fixed time (t [ms] in FIG. 6) after detecting whether or not the optical sensor is shielded from light by the filler. Control to move to the position However, when the power is turned off, even if the cam position is stored immediately before the power is turned off, it is often stored in the volatile memory. Therefore, it is necessary to rotate the cam again to recognize the cam position. In addition, when the contact / separation cam is attached to the intermediate transfer unit that can be detached from the apparatus main body, the positional relationship between the contact / separation cam on the intermediate transfer unit side and the drive source on the main body side is increased as the intermediate transfer unit is detached. Therefore, it is necessary to detect the position by rotating the cam (repeating contact and separation) after resetting the intermediate transfer unit.

  By the way, the secondary transfer means generally employs a system in which the pressure is applied to the opposing roller in the intermediate transfer unit, and when it abuts and suddenly collides with the opposing roller, the collision noise increases. May be pointed out as an abnormal sound. This collision sound is difficult to be manifested when other members are moving, such as during image formation. May cause the secondary transfer contact sound to protrude and become a complaint as an abnormal sound.

  In addition, the relationship in which the secondary transfer unit as the transfer nip forming member is brought into contact with and separated from the intermediate transfer member corresponds to the relationship in which the transfer roller as the transfer nip forming member is brought into contact with and separated from the photosensitive member. The contact noise of the transfer roller in the image forming apparatus of the type directly transferring to the recording medium may be a problem as well.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus in which the transfer means can be brought into contact with and separated from the image carrier, and the magnitude of the contact sound can be changed without adding a special additional mechanism, and the image forming production It is to provide a configuration that does not lose its gender.

  In order to solve the above problems, according to the present invention, an image carrier that carries a toner image, a transfer unit that transfers a toner image on the image carrier, and the image carrier and the transfer unit are brought into contact with each other. A contact / separation mechanism that separates, a first drive unit that drives the contact / separation mechanism, a second drive unit that drives other members other than the contact / separation mechanism, and a control unit that controls these drive units independently of each other And the second drive means has a first contact speed at which the contact / separation mechanism makes the image carrier and the transfer means contact when the second drive means is not driving the other member. The first drive means is controlled so that the contact / separation mechanism is slower than a second contact speed for contacting the image carrier and the transfer means when the other member is driven.

  When other members other than the contact / separation mechanism in the image forming apparatus are not operating, the contact sound of the contact / separation mechanism is likely to be manifested. It is possible to avoid receiving abnormal sound indications. When a member other than the contact / separation mechanism is operating, the contact sound of the contact / separation mechanism is mixed with the operating sound, so that, for example, image formation productivity is maintained without reducing the contact speed during image formation. be able to.

1 is a schematic configuration diagram of a tandem indirect transfer radiation device according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an intermediate transfer unit in an example in which a single secondary transfer roller is used instead of the belt-type secondary transfer device in FIG. 1. FIG. 3A shows the contact state and FIG. 3B shows the contact state of the secondary transfer device. This shows the relationship between cam displacement speed and noise. The contour of the cam is shown on the left side, and the relationship graph is shown on the right side. The relationship between the rotation direction of the contact / separation cam, the contact time, and the displacement speed is shown. It is a schematic diagram explaining the detection of a cam phase.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows a tandem indirect transfer type copying apparatus according to an embodiment of the present invention.

  The copying machine main body is provided with an endless belt-shaped intermediate transfer member 11 in the center of the casing. As conventionally known, the intermediate transfer belt 11 has a multilayer structure, and its base layer is made of, for example, a fluororesin such as Teflon (registered trademark) or polyvinylidene fluoride (PVDF) with little elongation, or a polyimide resin. The surface is covered with a smooth coat layer (fluorine resin or the like). In the illustrated example, the intermediate transfer belt 11 is wound around the support rollers 10, 12, 34, 35, 13, and 14 so that it can be rotated and conveyed counterclockwise in the drawing. Among these support rollers, for example, the support roller 34 is a drive roller and also functions as a secondary transfer counter roller. The support roller 13 is a cleaning facing roller, and the support rollers 10, 12, 35, and 14 are tension rollers.

  In the illustrated example, an intermediate transfer body cleaning device 25 for removing residual toner remaining on the intermediate transfer belt 11 after the secondary transfer is provided on the support roller 13. On the lower side of the intermediate transfer belt 11 stretched between the support roller 12 and the support roller 34, four image forming units of black, yellow, magenta, and cyan are arranged side by side along the conveyance direction. By disposing, a tandem image forming unit is configured. Each image forming unit includes a charging unit 3, a developing unit 5, a cleaning unit 2, and the like around the photoreceptor 1, and a primary transfer roller 20 is also provided on the inner peripheral side of the intermediate transfer belt 11.

  An exposure apparatus 4 is further provided below the tandem image forming unit as shown in FIG. On the other hand, a secondary transfer device is provided on the side facing the support roller 34. In the example shown in the figure, the secondary transfer device spans an endless secondary transfer belt 100 between two rollers 111, 112 and presses the secondary transfer belt 100 to the support roller 34. 113, and the pressing roller 113 is pressed against the support roller 34 via the secondary transfer belt 100 and the intermediate transfer belt 11, whereby the image on the intermediate transfer belt 11 is applied to the sheet P as a recording medium. Transcript. As the secondary transfer device, as shown in FIG. 2, a single secondary transfer roller may be used.

  A fixing device 30 for fixing the transferred image on the sheet is provided above the secondary transfer device. The fixing device 30 is of a type that presses a pressure roller against a fixing roller.

  The secondary transfer device in the illustrated example also has a sheet conveying function for conveying the sheet after image transfer to the fixing device 30. As described above, when a single transfer roller is arranged as the secondary transfer device, the sheet conveyance is executed by attaching another conveyance unit.

  When a start switch (not shown) is pressed, the support roller 34 is driven to rotate by the drive motor, the other five support rollers are driven to rotate, and the intermediate transfer belt 11 is rotated and conveyed. At the same time, the photosensitive member 1 is rotated by individual image forming means to form monochrome images of black, yellow, magenta, and cyan on each photosensitive member 1, respectively. Then, along with the conveyance of the intermediate transfer belt 11, these single color images are sequentially transferred to form a composite color image on the intermediate transfer belt 11.

  When the start switch is pressed, one of the paper feed rollers 27 of the paper feed table is selectively rotated, and the sheet P is fed out from one of the paper feed cassettes 26 provided in multiple stages in the paper bank. Each sheet is separated and put into the paper feed path 29, transported by a transport roller (not shown), guided to the paper feed path in the copying machine main body, and abutted against a timing adjustment / skew correction roller 28 called a so-called registration roller. stop.

  Then, the timing adjustment / skew correction roller 28 is rotated in synchronization with the composite color image on the intermediate transfer belt 11, the sheet is fed between the intermediate transfer belt 11 and the secondary transfer device, and transferred by the secondary transfer device. A color image is recorded on the sheet.

  The image-transferred sheet is conveyed by the secondary transfer belt 100 and sent to the fixing device 30. The fixing device 30 applies heat and pressure to fix the transferred image, and is then discharged by the discharge roller 32 and discharged. Stacked on the tray 40. The intermediate transfer belt 11 after the secondary transfer is prepared for re-image formation by the tandem image forming unit by removing residual toner remaining on the intermediate transfer belt 11 by the intermediate transfer body cleaning device 25.

  The characteristic configuration of the present invention will be described below. FIG. 2 is a schematic configuration diagram of an intermediate transfer unit in an example in which a single secondary transfer roller 36 is used instead of the belt-type secondary transfer device in FIG. 1, and the other parts are the same as those depicted in FIG. doing. The intermediate transfer belt 11 having a multilayer structure is wound around the support rollers 10, 12, 34, 35, 13, and 14 so as to be able to rotate and convey counterclockwise in the drawing. As in the example of FIG. 1, among these support rollers, for example, the support roller 34 is a drive roller, and also serves as a secondary transfer counter roller for the secondary transfer roller 36. The support roller 13 is a cleaning facing roller, and is disposed to face the intermediate transfer body cleaning device 25 that removes residual toner remaining on the intermediate transfer belt 11 after the secondary transfer. The support rollers 10, 12, 35, and 14 are tension rollers, and in particular, the support roller 10 mainly functions to apply a constant tension to the intermediate transfer belt 11, and 1 between the support roller 35 and the support roller 12. The next transfer nip is stabilized. Further rollers 20 arranged on the inner peripheral side of the intermediate transfer belt are primary transfer rollers, and four rollers 20 are provided corresponding to the image forming means for each color of black, yellow, magenta, and cyan.

  The secondary transfer unit is configured to have a mechanism for separating from the intermediate transfer member. For example, as shown in FIG. 3, the secondary transfer unit is provided on the same axis as the secondary transfer counter roller in the intermediate transfer unit. The secondary transfer means is brought into and out of contact with the contact / separation cam 37. The drive source M ′ for rotating the contact / separation cam 37 is controlled by a CPU (FIG. 1) as a control unit, and includes a support roller 34 that rotates and conveys the intermediate transfer belt 11, an image forming unit, a secondary transfer device, It is a motor that is driven independently from the drive motor (not shown) that drives other members in the image forming apparatus such as the fixing device 30 and the sheet conveying device. The secondary transfer unit pressurizes the opposing roller in the intermediate transfer unit by the pressurizing unit. When the secondary transfer unit suddenly collides with the opposing roller at the time of secondary transfer contact, a collision sound is generated. Becomes larger.

  In the contactable and separable pressure-type secondary transfer roller shown in FIGS. 2 and 3, the cam profile and the cam rotation speed were evaluated in the range of the total pressure 30N to 60N. It was found that the contact sound depends on the displacement speed of the cam output (in FIG. 4, the amount that the distance r from the rotation axis to the cam profile outer peripheral portion, which is the contact point, changes per unit time by rotation) (graph in FIG. 4). ). As the cam displacement speed increases, the contact noise increases. When the displacement speed of the cam output was gradually reduced to 0.02 mm / msec or less, it was below 60 dB, which was recognized as a level that was not noticed by sensory evaluation of noise.

  If such secondary transfer means contact speed has a plurality of modes and at least one secondary transfer contact speed is set to 0.02 mm / msec or less at the displacement speed of the contact / separation cam output, the print speed It is possible to selectively use the contact time reduction mode in which importance is placed on and the impact sound reduction mode by contact.

  In the initialization operation immediately after the intermediate transfer unit is set in the apparatus main body, other members in the image forming apparatus other than the contact / separation cam are not operating during the initialization operation. Even if the contact operation of the secondary transfer unit at that time is delayed, the printing speed is not affected. Therefore, the contact operation speed is set to 0.02 mm / msec or less at the displacement speed of the contact / separation cam output. Reduction of impact sound can be achieved. Further, when the other members in the image forming apparatus are operated, for example, when the image is formed, the printing speed is ensured by not decreasing the contact operation speed. That is, by providing a plurality of contact operation speeds, it is possible to ensure both the printing speed and the impact sound reduction. In the system having the contact / separation cam on the secondary transfer counter roller in the intermediate transfer unit, it is necessary to always perform the initialization operation when the intermediate transfer unit is attached / detached. It is particularly effective.

  As a method of switching the operation speed for contacting / separating to the secondary transfer unit, it is conceivable to switch the rotation direction of the contacting / separating cam having an asymmetric cam profile. As shown in FIG. 5, the contact / separation cam 37 ′ having an asymmetric cam profile can be rotated in both the clockwise and counterclockwise directions, so that the rotation direction can be adjusted even if the contact / separation cam is moved at the same rotational speed. Can change the cam output displacement speed and the contact time. As an example, in the cam profile shown in FIG. 5, when switching the forward / reverse rotation with the rotation speed fixed at 72 rpm, when the cam is rotated clockwise, the displacement speed exceeds 0.02 mm / msec and the noise is 60 dB or more. However, the contact time is as short as 140 msec, and when rotating counterclockwise, the contact time takes 280 msec, which is twice as large as the clockwise direction, but the displacement speed is smaller than 0.02 mm / msec, and the noise is less than 60 dB. It became a level not to be worried about. With such a configuration, even when the rotation speed of the contact / separation cam cannot be switched, the contact speed of the secondary transfer unit can be switched, and the contact time shortening mode and the noise reduction mode can be set and switched.

  As described above, in the secondary transfer nip where the secondary transfer roller 36 is brought into contact with the intermediate transfer belt 11, contact / separation means for bringing the secondary transfer roller 36 into and out of contact with the secondary transfer counter roller 34 via the intermediate transfer belt 11 is used. Although an example in which the invention is applied has been described, it is also possible to apply the present invention to a method of directly transferring from a photosensitive drum to a sheet as a recording medium. In other words, in the primary transfer nip where the drum-shaped photoconductor as the image carrier and the transfer roller as the transfer nip forming member abut, an eccentric contact cam can be provided on the rotating shaft of the photoconductor so as to be able to idle. .

11 Intermediate transfer belt 34 Transfer facing roller (drive roller, support roller)
35 Tension roller (support roller)
36 Secondary transfer roller 37 Contact / separation cam

Japanese Patent No. 4579394 JP 2010-19964 A

Claims (8)

  An image carrier for carrying a toner image; transfer means for transferring a toner image on the image carrier; contact / separation mechanism for contacting / separating the image carrier and the transfer means; and driving the contact / separation mechanism First driving means for driving, second driving means for driving members other than the contact / separation mechanism, and control means for controlling these driving means independently of each other, wherein the second driving means drives the other members. When the second drive means is driving the other member, the contact / separation mechanism has a first contact speed at which the contact / separation mechanism contacts the image carrier and the transfer means. The image forming apparatus is characterized in that the first driving unit is controlled to be slower than a second contact speed at which the image carrier and the transfer unit come into contact with each other.   The image forming apparatus according to claim 1, wherein the image carrier is an intermediate transfer member, and the transfer unit is a secondary transfer unit.   The image forming apparatus according to claim 1, wherein the image carrier is a photoconductor, and the transfer unit is a transfer roller that performs transfer to a recording medium.   The other member is at least one of an image forming unit, the secondary transfer unit, a transport device that transports the recording medium in the image forming apparatus, and a fixing device that fixes the toner image that has been secondarily transferred onto the recording medium. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.   An intermediate transfer unit that supports the intermediate transfer member and is detachable and attachable to the image forming apparatus main body, and the control means immediately after the intermediate transfer unit is attached to the image forming apparatus main body. 5. The image forming apparatus according to claim 2, wherein the image carrier and the transfer unit are brought into contact with each other at a contact speed of 1.   6. The first contact speed is set to 0.02 mm / msec or less, and the second contact speed is set to be greater than 0.02 mm / sec. 6. Image forming apparatus.   2. The contact / separation mechanism includes an approach / separation cam, and the first contact speed and the second contact speed are realized by switching a rotation direction of the contact / separation cam. The image forming apparatus according to claim 1.   The image according to claim 7, wherein an outer peripheral contour of the contact / separation cam is formed asymmetrically, and the first contact speed and the second contact speed are realized by switching a rotation direction thereof. Forming equipment.

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