JPH096147A - Image recorder - Google Patents

Abstract

PURPOSE: To improve image quality by performing the attaching/detaching control of a secondary transfer roller and a cleaner while preventing the staining of the secondary transfer roller and surely removing remaining toner with the cleaner, and also, to prevent the occurence of an electromagnetic noise due to the voltage impression on the secondary transfer roller. CONSTITUTION: The length L2 of a 1st area from the primary transfer part to the secondary transfer part of an intermediate transfer belt 40 is set equal to or exceeding the length of the area of the toner image primarily transferred to the belt 40. And, only when the toner image exists within the 1st area A, such a control is performed that the secondary transfer roller 47 and a cleaning blade 51 are permitted to come into press-contact with the belt 40, or to separate from the belt 40. And also, a switching operation by a developing device switching motor for placing a prescribed developing device opposite to a photoreceptor drum 10 is performed at a timing capable of bringing the roller 47 and the cleaning blade 51 into press-contact with the belt 40, or separating the roller 47 and the blade 51 from the belt 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus provided with an intermediate transfer member for primary transfer of a toner image, and particularly to contact and separation (hereinafter also referred to as contact and separation) with respect to an intermediate transfer belt. The present invention relates to a device in which image quality is improved by controlling contact / separation between a secondary transfer roller that is arranged as much as possible and a cleaner for removing residual toner.

[0002]

2. Description of the Related Art Conventionally, an image recording apparatus having an intermediate transfer member has been known, and for example, Japanese Patent Publication No. 6-105377.
The publication discloses a compact and low-cost full-color printer that uses a flexible transfer belt as an intermediate transfer member.

In such a printer, the image developed on the photoreceptor is first transferred to the image transfer station (1
In the secondary transfer portion), primary transfer is performed on the transfer belt, and a plurality of colors are overlaid. Then, the composite-developed toner image is secondarily transferred to a sheet as an image receptor at a composite image transfer station (secondary transfer portion).

Here, a movable secondary transfer roller is arranged in the composite image transfer station so that it can be moved in contact with or away from the transfer belt or selectively moved under the control of the controller. Has become.

[0005]

However, when the secondary transfer roller or the cleaner for removing the residual toner is brought into contact with or separated from the transfer belt during the primary transfer to the transfer belt, the transfer belt vibrates. May occur and the primary transfer image may be distorted, and if the cleaner is brought into contact with or separated from the transfer belt during the secondary transfer onto the paper, the secondary transfer image may be distorted. Therefore, there is a problem that the image quality is deteriorated.

Further, when the secondary transfer roller and the cleaner are brought into contact with and separated from the transfer belt, if both the secondary transfer roller and the cleaner are brought into contact with and separated from each other at the same time, the vibration generated in the transfer belt becomes large, resulting in the transfer. There is a risk that the toner image placed on the belt may be adversely affected.

On the other hand, if the secondary transfer roller is kept in contact with the transfer belt for an unnecessarily long time, there is a risk that residual toner on the transfer belt will adhere and show off on the paper. With regard to the cleaner, there is a possibility that toner may be left unwiped on the transfer belt if the contact time with the transfer belt is short.Therefore, while solving these problems of show-through and unwiped toner, It has been extremely difficult to perform the contact / separation operation of the secondary transfer roller and the cleaner.

Further, the secondary transfer is performed by applying a voltage to the secondary transfer roller. When the secondary transfer roller is brought into contact with or separated from the transfer belt with such a voltage applied, the secondary transfer roller is discharged. There was also a problem that electromagnetic noise was generated.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to prevent dirt on the secondary transfer roller and to reliably remove residual toner by a cleaner. The contact / separation control improves the image quality and prevents the generation of electromagnetic noise due to the voltage application to the secondary transfer roller.

[0010]

The present invention for achieving the above object is constructed as follows for each claim. According to another aspect of the present invention, there is provided a photosensitive member on which an electrostatic latent image is formed by charging and exposure, a developing unit for developing the electrostatic latent image formed on the photosensitive member, and a developed photosensitive member. An intermediate transfer member on which the toner image on the body is primarily transferred, and a primary transfer unit that presses the intermediate transfer member toward the photoconductor to form the primary transfer unit on which the primary transfer is performed. A transfer member,
A secondary transfer member that is arranged so as to be able to come into contact with and separate from the intermediate transfer member, and a toner image on the intermediate transfer member is secondarily transferred to a recording sheet at a contact portion with the intermediate transfer member. An image recording apparatus having a secondary transfer member for forming a secondary transfer portion and a cleaner for contacting and separating from an intermediate transfer member and removing residual toner on the intermediate transfer member, The first detection means for detecting whether or not the transfer is being performed, the second detection means for detecting whether or not the secondary transfer is being performed, and the primary detection means by the first and second detection means. When it is detected that neither the transfer nor the secondary transfer has been performed, the control device has a control means for controlling the secondary transfer member and the cleaner to contact or separate from the intermediate transfer member. This is an image recording device.

According to a second aspect of the present invention, in the image recording apparatus according to the first aspect, the intermediate transfer member is provided with a first area from a primary transfer section to a secondary transfer section and a secondary area. When divided into a second region from the transfer part to the contact part with the cleaner and a third region from the contact part with the cleaner to the primary transfer part, at least one of these first to third regions Is set to a length that is equal to or longer than the area of the toner image that is primarily transferred to the intermediate transfer member, and the control unit controls the leading edge and the trailing edge of the toner image to be equal to or longer than the area of the toner image. It is characterized in that the secondary transfer member and the cleaner are brought into contact with or separated from the intermediate transfer member at a timing in any one of the first to third regions having the above.

According to a third aspect of the present invention, in the image recording apparatus according to the first or second aspect, the control means brings the secondary transfer member and the cleaner into contact with the intermediate transfer body at different timings. Alternatively, it is characterized by performing control to separate them.

According to a fourth aspect of the present invention, in the image recording apparatus according to the third aspect, the control means is
When the secondary transfer member and the cleaner are brought into contact with the intermediate transfer member, the cleaner and the secondary transfer member are brought into contact with each other in that order.
When the next transfer member and the cleaner are separated from the intermediate transfer member, the secondary transfer member and the cleaner are controlled to be separated in this order.

According to a fifth aspect of the present invention, in the image recording apparatus according to any one of the first to fourth aspects,
The control means applies a voltage to the secondary transfer member for secondary transfer after bringing the secondary transfer member into contact with the intermediate transfer member, and at the same time applies the voltage to the secondary transfer member for secondary transfer. The present invention is characterized in that control is performed such that the secondary transfer member is separated from the intermediate transfer member after the voltage application is stopped.

According to a sixth aspect of the present invention, in the image recording apparatus according to the first or second aspect, the developing means includes a plurality of developing devices and a predetermined developing device among them as a photoconductor. And a developing device switching unit for operating the developing unit switching unit at a timing at which the secondary transfer member and the cleaner can be brought into contact with or separated from the intermediate transfer member. And

[0016]

According to the present invention having the above-described structure, each claim operates as follows. According to the first aspect of the invention, when the first and second detection means detect that neither the primary transfer nor the secondary transfer is performed, that is, the transfer timing of the image is removed. Then, control is performed to bring the secondary transfer member and the cleaner into contact with or away from the intermediate transfer member.

In a second aspect of the present invention, both the front end and the rear end of the toner image are any one of the first to third regions having a length equal to or longer than the region of the toner image. Control is performed so that the secondary transfer member and the cleaner are brought into contact with or separated from the intermediate transfer member only at a timing in the area, that is, when the toner image is contained in the area having one image or more. Be seen.

According to the third aspect of the present invention, control is performed to bring the secondary transfer member and the cleaner into contact with or separate from the intermediate transfer member at different timings.

According to a fourth aspect of the invention, the cleaner and the secondary transfer member are brought into contact with the intermediate transfer member in this order, and
Control for separating the next transfer member and the cleaner is performed in this order.

According to the fifth aspect of the present invention, after the secondary transfer member is brought into contact with the intermediate transfer member, the voltage is applied to the secondary transfer member and the voltage is applied to the secondary transfer member. After the stop, the control for separating the secondary transfer member from the intermediate transfer body is performed. Therefore, the secondary transfer member is contacted with or separated from the intermediate transfer body with the voltage always turned off.

According to the sixth aspect of the invention, the developing device switching means operates at a timing at which the secondary transfer member and the cleaner can be brought into contact with or separated from the intermediate transfer body. Occurrence of vibration accompanying the developing device switching operation is allowed only when the image transfer timing is off.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of a full-color laser beam printer according to an embodiment of the image recording apparatus of the present invention, and FIG. 2 is a view showing an internal mechanism of the printer shown in FIG.

Referring to FIG. 2, the printer 1 is shown as follows.
A photoconductor drum (corresponding to a photoconductor) 10 which is rotationally driven in the direction of arrow a, a laser scanning optical system 20, a full-color developing device (corresponding to developing means) 30, and an endless device which is rotationally driven in the direction of arrow b. The intermediate transfer belt (corresponding to an intermediate transfer member) 40 and a sheet feeding unit 60 are configured. Around the photosensitive drum 10, a charging brush 11,
The cleaner 12 is installed. The charging brush 11 uniformly charges the surface of the photoconductor drum 10 to a predetermined potential. The cleaner 12 uses the blade 12a to move the photosensitive drum 10
The remaining toner is scraped off.

The laser scanning optical system 20 is a well-known one having a laser diode, a polygon mirror, and an fθ optical element built therein, and the CPU 100 (see FIG. 4) as its control means.
C (cyan), M (magenta), Y (yellow),
Print data for each Bk (black) is transferred from the host computer. The laser scanning optical system 20 sequentially outputs the print data for each color as a laser beam, and scans and exposes the photosensitive drum 10. With this, the photosensitive drum 1
An electrostatic latent image for each color is sequentially formed on 0.

The full-color developing device 30 includes C, M, Y, B
four color developing units 3 containing a developer containing k toner
1C, 31M, 31Y, and 31Bk are integrally attached to the developing rack 80, and the developing rack 80 can rotate in a clockwise direction with a support shaft 81 as a fulcrum. Each developing device serves as developing device switching means (not shown) so that the developing sleeve 32 of the corresponding developing device is positioned at the developing position D each time an electrostatic latent image of each color is formed on the photoconductor drum 10. It is switched by being rotated by a quarter rotation by the device switching motor. In this embodiment, the entire printer is made compact by using the rotary type full-color developing device 30.

The intermediate transfer belt 40 includes support rollers 41, 4
2 and tenon rollers 43, 44 are endlessly stretched, and are rotationally driven in the direction of arrow b in synchronization with the photoconductor drum 10. A belt mark (not shown) is provided on the side of the intermediate transfer belt 40 for aligning the leading edge of the color image, and the photosensor 45 detects the belt mark to perform image forming processing such as exposure, development, and transfer. Is controlled. It is also possible to use a micro switch or the like instead of the photo sensor 45. Intermediate transfer belt 40
Is pressed by a rotatable primary transfer roller (corresponding to a primary transfer member) 46 and comes into contact with the photosensitive drum 10, and this contact portion is the primary transfer portion.

Further, the intermediate transfer belt 40 includes the support roller 4
The rotatable secondary transfer roller (corresponding to a secondary transfer member) 47 faces the horizontal conveyance path 65 of the recording sheet, which will be described below, at a portion supported by the second transfer roller 40 so that the secondary transfer roller 47 can contact and separate from the intermediate transfer belt 40. Will be placed. The contact portion between the intermediate transfer belt 40 and the secondary transfer roller 47 is the secondary transfer portion. In addition,
A secondary transfer roller solenoid (not shown) for pressing and separating the secondary transfer roller 47 from the intermediate transfer belt 40 is provided.

Further, a cleaner 50 is installed in the space between the developing device 30 and the intermediate transfer belt 40. The cleaner 50 has a cleaner blade 51 for scraping off the residual toner on the intermediate transfer belt 40.
The cleaner blade 51 can be brought into contact with and separated from the intermediate transfer belt 40 by a cleaner solenoid (not shown).

The paper feed section 60 is composed of a paper feed tray 61 which can be opened on the front side of the printer body 1 (on which the operator is normally located), a paper feed roller 62, and a timing roller 63. The recording sheet S has a paper feed tray 61.
The sheets are stacked on top of each other and are fed one by one to the right in FIG. 2 by the rotation of the sheet feeding roller 62, and the secondary transfer is performed in synchronization with the image formed on the intermediate transfer belt 40 by the timing roller 63. Sent to the department. The horizontal conveyance path 65 for the recording sheet is composed of an air suction belt 66, etc.
Is provided with a vertical transport path 71 having transport rollers 72, 73, and 74. The recording sheet S is discharged from the vertical transport path 71 to the upper surface of the printer body 1.

Here, the outline of the full-color printing operation in this embodiment will be described. At the start of the printing operation, the secondary transfer roller 47 and the cleaning blade 51 are separated from the intermediate transfer belt 40. When the printing operation is started, the photosensitive drum 10 is rotationally driven in the arrow a direction and the intermediate transfer belt 40 is rotationally driven in the arrow b direction at the same peripheral speed, and the photosensitive drum 10 is charged by the charging brush 1.
1 is charged to a predetermined potential.

Subsequently, the laser scanning optical system 20 exposes the cyan image, and an electrostatic latent image of the cyan image is formed on the photosensitive drum 10. This electrostatic latent image is immediately developed by the developing device 31C, and the toner image is transferred onto the intermediate transfer belt 40 in the primary transfer section. After the completion of the primary transfer, the developing device 31M is switched to the developing position D, and subsequently, exposure, development and primary transfer of the magenta image are performed. Thereafter, similarly, switching to the developing device 31Y, exposure, development, and primary transfer of the yellow image are performed. Further, the developing device 31B
Switching to k, exposure of a black image, development, and primary transfer are performed, and a toner image is superimposed on the intermediate belt 40 for each primary transfer.

When the final primary transfer is completed, the developing device 3
0 is switched to the developing device 31C for the next print processing, and the secondary transfer roller 47 and the cleaning blade 51 are brought into pressure contact with the intermediate transfer belt 40. At this time, the recording sheet S is sent to the secondary transfer portion, and the intermediate transfer belt 4
The full-color toner image formed on the recording sheet 0 is transferred onto the recording sheet. When this secondary transfer is completed, the secondary transfer roller 47 and the cleaning blade 51 are separated from the intermediate transfer belt 40.

FIG. 3 is a schematic view of the periphery of the intermediate transfer belt shown in FIG. Particularly in this embodiment, as shown in FIG. 3, the intermediate transfer belt 40 is brought into contact with the first area A from the primary transfer portion to the secondary transfer portion and the cleaning blade 51 of the cleaner 50 from the secondary transfer portion. Second area B up to part
And a third area C from the contact portion with the cleaning blade 51 to the primary transfer portion, the length of the first area A is equal to or larger than the area of the toner image primarily transferred to the intermediate transfer belt 40. Is set to the length of. Then, control is performed to allow the secondary transfer roller 47 and the cleaning blade 51 to be pressed against or separated from the intermediate transfer belt only when the toner image is contained in the first area A. Is composed of. Further, the switching operation by the developing device switching motor for causing the predetermined developing device to face the photoconductor drum 10, that is, the clockwise rotating operation of the developing rack 80 is also performed by the above-described secondary transfer roller 47 and cleaning blade 51. Is performed at a timing when it can be pressed against or separated from the intermediate transfer belt 40.

That is, the circumference from the exposure position of the laser beam on the photosensitive drum 10 to the end of the area (first area A in this embodiment) set to have a length longer than the area of the toner image primarily transferred. The length along the direction is L1 (mm), and the length along the circumferential direction of the area (the first area A in this embodiment) set to be longer than the area of the toner image to be primarily transferred is L2 ( mm), the time from the start of exposure is (L1 + L0) / V to (L1 + L2) / V
During (seconds), control is performed to allow the secondary transfer roller 47, the cleaning blade 51 to move toward and away from the intermediate transfer belt 40, and the developing device switching operation. Here, L0 represents the length L0 (mm) of the recording sheet S, V represents the system speed V (mm / sec), and this system speed V
Corresponds to the feeding speed of the intermediate transfer belt 40. In addition,
When the printing speed of the printer is n (prints / minute), the number of color overlaps is k, and the peripheral length of the intermediate transfer belt 40 is L (mm), V = nkL / 60.

As described above, noise on the image can be prevented by performing the operation of causing the mechanical vibration at a timing other than the image transfer timing.

Further, in the present embodiment, when the secondary transfer roller 47 and the cleaning blade 51 are brought into pressure contact with the intermediate transfer belt 40, the cleaning blade 51 and the secondary transfer roller 47 are brought into pressure contact with each other in this order. When the cleaning blade 51 is separated from the intermediate transfer belt 40, the secondary transfer roller 47 and the cleaning blade 51 are separated in this order.
Therefore, it is possible to avoid a situation in which both the secondary transfer roller and the cleaner are brought into contact with and separated from each other at the same time to generate a large vibration on the transfer belt, and the secondary transfer roller and the cleaner are pressed into contact with each other or separated from each other. It is set so that the cleaning time is certainly long and the pressure contact time of the secondary transfer roller is short.

The secondary transfer to the recording sheet S is performed by applying a voltage to the secondary transfer roller 47, but in the present embodiment, the secondary transfer roller 47 is pressed against the intermediate transfer belt 40 and then the secondary transfer is performed. While applying the voltage to the transfer roller 47 and stopping the application of the voltage to the secondary transfer roller 47, the secondary transfer roller 47 is separated from the intermediate transfer belt 40. Therefore, since the secondary transfer roller 47 is pressed and separated from the intermediate transfer belt 40 with the voltage always turned off, it is possible to prevent discharge and noise.

FIG. 4 is a schematic block diagram of the printer shown in FIG. The printer 1 of the present embodiment has a CPU 100 as a control means, and the CPU 100
Includes the photo sensor 45, the developing device switching motor, and
A secondary transfer roller solenoid and a cleaner solenoid are connected, a high-voltage output unit that is built in the secondary transfer roller and applies a voltage for secondary transfer, and a laser diode as a light source that turns on / off laser light irradiation. A polygon motor for controlling the rotation of the Bolgon mirror irradiated with light from the laser diode, an operation panel 3 (see FIG. 1) for various operations and various displays by an operator, and other control mechanisms are connected.

The CPU 100 receives the print signal from the operation panel 3, determines the timing of the primary transfer and the secondary transfer based on the detection result of the belt position of the intermediate transfer belt 40 by the photo sensor 45, and the printer 1
It controls the operation of each internal mechanism, charging, exposure, development, 1
A series of printing operations such as secondary transfer and secondary transfer are collectively controlled. The CPU 100 and the photo sensor 4
Reference numeral 5 constitutes the first and second detecting means for detecting the timing of performing the primary transfer and the secondary transfer.

Next, the operation of the printer of this embodiment will be described with reference to FIG.
The contact and separation control of the secondary transfer roller and the cleaner will be mainly described with reference to the flowchart shown in FIG. FIG.
Is a main control flow of the printer shown in FIG. 1, FIG. 6 is a print control subroutine shown in FIG. 5, FIG. 7 is a developing device switching control subroutine shown in FIG. 5, and FIG. 8 is a secondary control shown in FIG. It is a subroutine of transfer roller and cleaner pressure contact / separation control.

As shown in FIG. 5, when the printer 1 is powered on, the CPU 100 is initialized (step S1), and the internal timer of the CPU 100 is started (step S2). Next, the CPU 100 performs print control for primary transfer of the toner image onto the intermediate transfer belt 40 (step S3), developing device switching control for switching to a predetermined color developing device (step S4), and toner image recording sheet. The secondary transfer roller and the cleaner pressure contact / separation control for removing the residual toner on the intermediate transfer belt 40 as well as the secondary transfer to S (step S5), and other control for feeding the recording sheet S and the like are performed. . In step S7, the time-up of the internal timer is counted and a time waiting process is performed.

In the print control (step S3 in FIG. 5), as shown in FIG.
When the PU 100 recognizes that the print signal is on, the process proceeds to state 1. When the photo sensor 45 detects the belt mark on the intermediate transfer belt 40, the laser scanning optical system 20 starts the exposure on the photosensitive drum 10, and the timer Ta1 (= L0 / V, the recording sheet S (Required feeding time for the length of) is set, and the process proceeds to state 2. Next, in state 2, the CPU 100
Exposure is prohibited at the time when the timer Ta1 counts up, and timer Ta2 (= L1 / V, the required feed for the length in the circumferential direction from the exposure position to the end of the first area A shown in FIG. 3). Time) is set and the process proceeds to state 3.
In addition, at a predetermined timing after the exposure, the developing device 30
By this, the electrostatic latent image of the first color of the color printing formed by being exposed on the photoconductor drum 10 is developed, and the toner image is primarily transferred onto the intermediate transfer belt 40 at the primary transfer portion.

In this embodiment, in particular, the CPU 100 sets the secondary transfer roller and the cleaner pressure contact / separation permission flag when the timer Ta2 counts up, and the timer Ta3 (= (L2-L0) / V). , The required feeding time for the length obtained by subtracting the length of the recording sheet S from the length of the first area A in FIG. 3 is set, and the process proceeds to state 4. Next, in the state 4, the CPU 100 clears the secondary transfer roller and cleaner pressure contact / separation permission flag at the time when the timer Ta3 counts up. As described above, the secondary transfer roller 47 and the cleaning blade 51 are attached to the intermediate transfer belt 40 only when the toner image is contained in the first area A (see FIG. 3) which is one image or more. Since the control for permitting the pressure contact or the separation is performed, it is possible to easily avoid the mechanical vibration that may appear as noise in the image due to the contact and separation operations.

When the secondary transfer roller and the cleaner pressure contact / separation permission flag are cleared in the state 4, it is judged whether or not the fourth color is printed, and if it is not the fourth color, the process returns to the state 1 and the second color to Toner images up to the fourth color are sequentially superposed on the intermediate transfer belt 40.

In the developing device switching control (step S4 in FIG. 5), first, as shown in FIG. 7, the process proceeds to state 0, and the belt mark on the intermediate transfer belt 40 is detected by the photo sensor 45.
CP that controls switching timing by detecting with
When U100 recognizes that it is at the developing device switching timing, the developing device switching motor is turned on to rotate the developing rack 80 by a quarter with the support shaft 81 as the fulcrum. Next, in state 1, when it is recognized that the developing sleeve 32 of the predetermined color-specific developing unit has reached the developing position D, the developing unit switching motor is turned off. In the present embodiment, the switching operation by the developing device switching motor is configured to be performed at a timing at which the above-mentioned secondary transfer roller 47 and cleaning blade 51 can be pressed against or separated from the intermediate transfer belt 40. Therefore, the vibration caused by the switching operation of the developing device is allowed only when the toner image is present inside the first area A (see FIG. 3), which is equal to or more than one image. It is possible to prevent the generation of image noise due to the operation.

In the secondary transfer roller and cleaner pressure contact / separation control (step S5 in FIG. 5), as shown in FIG.
First, go to state 0. When the CPU 100 recognizes the setting state of the secondary transfer roller and the cleaner pressure contact / separation permission flag, if the developer to be primary-transferred is the first color, the process proceeds to state 1 and the secondary transfer roller 47 is moved to the intermediate transfer belt 40. The timer Tb1 is set and the cleaning blade 51 of the cleaner 50 is separated from the intermediate transfer belt 40 at the time when the timer Tb1 counts up in state 2. That is, 2
The cleaning blade 51 is separated after a lapse of a predetermined time Tb1 after the separation of the next transfer roller 47. For the set value of the timer, see (L2-L0
) / V = T, Tb1 <T is set. When the developer to be primarily transferred is the second or third color, the secondary transfer roller 47 and the cleaning blade 51 are held in a state of being separated from the intermediate transfer belt 40.

On the other hand, when the secondary transfer roller and the cleaner pressure contact / separation permission flag are set and it is recognized that the developer to be primarily transferred is the fourth color, the state 3 is set.
Then, the CPU 100 presses the cleaning blade 51 of the cleaner 50 against the intermediate transfer belt 40 and sets the timer Tb2 to set the timer Tb2 in the state 4
When the time-up of b2 is counted, the secondary transfer roller 47 is brought into pressure contact with the intermediate transfer belt 40. That is, after a predetermined time Tb2 has elapsed after the cleaning blade 51 has been pressed, the secondary transfer roller 47 is pressed.

Thus, with respect to the intermediate transfer belt 40,
Since the cleaning blade 51 and the secondary transfer roller 47 are pressed against each other in this order, and the secondary transfer roller 47 and the cleaning blade 51 are separated from each other in this order, both the secondary transfer roller and the cleaner are contacted and separated at the same time, and the intermediate transfer is performed. It is possible to avoid a situation in which a large vibration is generated on the belt, and ensure that the cleaning time is long and the pressure contact time of the secondary transfer roller is short in the short time in which the secondary transfer roller and the cleaner can be brought into contact with and separated from each other. Therefore, it is possible to achieve both the unwiping of the toner on the intermediate transfer belt and the prevention of contamination of the secondary transfer roller.

After a lapse of a predetermined time Tb3 after the secondary transfer roller 47 is pressed against the intermediate transfer belt 40, the high voltage output unit applies a voltage for the secondary transfer for a predetermined time Tb4.
Only (states 5 and 6), and the full-color image is transferred to the recording sheet S. In this way, the intermediate transfer belt 40 of the secondary transfer roller 47 is always in the state where the voltage is turned off.
Since the pressure contact and the separation are performed, the electromagnetic noise does not occur due to the discharge, and it is possible to avoid a situation in which electronic components inside and outside the machine are adversely affected.
For the set value of the timer, (Tb2 + Tb3) <T
And Tb4 is set to a value approximately equal to L0 / V.

9 and 10 are schematic views of the periphery of the intermediate transfer belt of a printer according to another embodiment.
The same parts as those shown in FIG. 3 are designated by the same reference numerals,
The description is partially omitted.

In the printer shown in FIG. 9, the length of the second area B from the secondary transfer portion of the intermediate transfer belt 40 to the contact portion of the cleaner 50 with the cleaning blade 51 is primarily transferred to the intermediate transfer belt 40. In the printer shown in FIG. 10, the length of the third region C from the contact portion of the intermediate transfer belt 40 with the cleaning blade 51 to the primary transfer portion is set. Is set to a length longer than the area of the toner image primarily transferred to the intermediate transfer belt 40. With this configuration, the inside of the area having the length L2 along the circumferential direction set to the length equal to or longer than the area of the toner image to be primarily transferred,
Only when the toner image is contained, it is possible to perform control to permit the secondary transfer roller 47 and the cleaning blade 51 to be brought into contact with and separated from the intermediate transfer belt. The same effect as can be obtained.

It should be noted that the above-described embodiments are described for facilitating the understanding of the present invention and not for limiting the present invention. Each disclosed element is intended to include all design changes and equivalents within the technical scope of the present invention. For example, in the above-described embodiments, the photoconductor drum is used as the photoconductor on which the electrostatic latent image is formed, but the present invention is not limited to this, and can be applied to a printer using a belt-shaped photoconductor. Is also applicable.

[0053]

As described above, according to the present invention, the following effects can be obtained for each claim. In the invention described in claim 1, when it is detected by the first and second detection means that neither the primary transfer nor the secondary transfer is performed, that is, when the image transfer timing is removed, 2 Since the control for contacting or separating the next transfer member and the cleaner with respect to the intermediate transfer member is performed, it is possible to reliably prevent the image noise caused by the contact and separation operations of these members.

In the invention described in claim 2, both the leading edge and the trailing edge of the toner image are in any one of the first to third areas having a length equal to or longer than the area of the toner image. Only at the timing, that is, when the toner image is present inside the area that is more than one image, 2
Since the control for bringing the next transfer member and the cleaner into contact with or away from the intermediate transfer member is performed, mechanical vibration that may appear as noise in an image due to the contact and separation operation of these members is facilitated. It can be avoided.

According to the third aspect of the invention, the secondary transfer member and the cleaner are controlled to come into contact with or separate from the intermediate transfer member at different timings.
It is possible to avoid a situation in which both the next transfer member and the cleaner are brought into contact with and separated from each other at the same time and a large vibration is generated in the intermediate transfer member.

According to the fourth aspect of the invention, since the cleaner and the secondary transfer member are brought into contact with the intermediate transfer member in this order, and the secondary transfer member and the cleaner are separated in this order, the secondary transfer is performed. It is possible to set the cleaning time to be surely long and the contact time of the secondary transfer member to be short in a short time in which the member and the cleaner can be separated from each other, and it is possible to wipe the toner on the intermediate transfer member. It is possible to achieve both prevention of contamination of the secondary transfer member.

According to the fifth aspect of the invention, the secondary transfer member is brought into contact with the intermediate transfer member, and then the voltage is applied to the secondary transfer member for the secondary transfer, and the secondary transfer member is subjected to the secondary transfer. Since the control of separating the secondary transfer member from the intermediate transfer member is performed after the voltage application to the secondary transfer member is stopped, the voltage of the secondary transfer member is always applied to the intermediate transfer member with the voltage turned off. Contact or separation is performed, whereby electromagnetic noise does not occur due to discharge, and it is possible to avoid a situation that adversely affects electronic components inside and outside the machine.

According to the sixth aspect of the present invention, the developing device switching means operates at a timing at which the secondary transfer member and the cleaner can be brought into contact with or separated from the intermediate transfer member. The generation of vibration accompanying the device switching operation is allowed only when the image transfer timing is off, and it is possible to prevent the generation of image noise accompanying the switching operation.

[Brief description of drawings]

FIG. 1 is an external view of a full-color laser beam printer according to an embodiment of an image recording apparatus of the present invention.

FIG. 2 is a diagram showing an internal mechanism of the printer shown in FIG.

FIG. 3 is a schematic diagram around the intermediate transfer belt shown in FIG.

FIG. 4 is a schematic block configuration diagram of the printer shown in FIG.

5 is a main control flow of the printer shown in FIG.

FIG. 6 is a print control subroutine shown in FIG.

FIG. 7 is a subroutine for developing device switching control shown in FIG.

FIG. 8 is a subroutine of the secondary transfer roller and cleaner pressure contact / separation control shown in FIG.

FIG. 9 is a schematic view around an intermediate transfer belt of another embodiment.

FIG. 10 is a schematic diagram around an intermediate transfer belt according to still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Photosensitive drum (photosensitive member), 30 ... Full-color developing device (developing means), 31C, 31M, 31Y, 31Bk ... Developing device, 40 ... Intermediate transfer belt (intermediate transfer member), 45 ... Photo sensor, 46 ... 1 Next transfer roller (primary transfer member), 47 ... Secondary transfer roller (secondary transfer member), 50 ... Cleaner, 51 ... Cleaning blade, 100 ... CPU (control means), A ... First area, B ... Second Area, C ... Third area, S ... Recording sheet,

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[Procedure amendment]

[Submission date] June 20, 1995

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

[Fig. 2]

[Procedure 3]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

[Figure 3]

[Procedure amendment 4]

[Document name to be amended] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction contents]

[Figure 9]

[Procedure Amendment 5]

[Document name to be amended] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction contents]

[Figure 10]

Claims (6)

[Claims] 1. A photosensitive member on which an electrostatic latent image is formed by charging and exposure, developing means for developing the electrostatic latent image formed on the photosensitive member, and a toner image on the developed photosensitive member. An intermediate transfer member on which primary transfer is performed; a primary transfer member that presses the intermediate transfer member toward a photoconductor to form a primary transfer portion on which the primary transfer is performed; and an intermediate transfer member A secondary transfer member that can be brought into contact with and separated from a body, and a secondary transfer in which a toner image on the intermediate transfer body is secondarily transferred to a recording sheet at a contact portion with the intermediate transfer body. In an image recording apparatus having a secondary transfer member that forms a portion and a cleaner that is disposed so as to come into contact with and separate from the intermediate transfer member and removes residual toner on the intermediate transfer member, the primary transfer is First detecting means for detecting whether or not the operation is performed; When it is detected by the second detecting unit that detects whether or not the transfer is being performed, and that neither the primary transfer nor the secondary transfer is being performed by the first and second detecting units, 2 An image recording apparatus comprising: a control unit that controls the next transfer member and the cleaner to contact or separate from the intermediate transfer member. 2. The intermediate transfer member is provided with a first area from a primary transfer section to a secondary transfer section, a second area from a secondary transfer section to a contact section with a cleaner, and a contact section with a cleaner. When divided into a third area up to the primary transfer portion, at least one of these first to third areas has a length longer than the area of the toner image primarily transferred to the intermediate transfer member. The control unit is set such that both of the leading edge and the trailing edge of the toner image are in any one of the first to third areas having a length equal to or longer than the area of the toner image. The image recording apparatus according to claim 1, wherein control is performed to bring the secondary transfer member and the cleaner into contact with or away from the intermediate transfer body. 3. The image recording apparatus according to claim 1, wherein the control unit controls the secondary transfer member and the cleaner to contact or separate from the intermediate transfer member at different timings. 4. The cleaner controls the cleaner when the secondary transfer member and the cleaner are brought into contact with the intermediate transfer member.
4. The secondary transfer member and the cleaner are controlled in such a manner that when the secondary transfer member and the cleaner are separated from the intermediate transfer member in this order, the secondary transfer member and the cleaner are separated in this order. Image recording device. 5. The control means applies a voltage to the secondary transfer member for the secondary transfer after bringing the secondary transfer member into contact with the intermediate transfer member, and at the same time for the secondary transfer member. The image recording apparatus according to any one of claims 1 to 4, wherein control is performed to separate the secondary transfer member from the intermediate transfer member after the voltage application to the secondary transfer member is stopped. 6. The developing device has a plurality of developing devices and a developing device switching device for exposing a predetermined developing device among them to a photoconductor, and the developing device switching device is a secondary device. The image recording apparatus according to claim 1 or 2, wherein the transfer member and the cleaner operate at a timing at which they can be brought into contact with or separated from the intermediate transfer member.