JP3312905B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a toner image on an image carrier which is driven to rotate, and primary-transferring the toner image onto an intermediate transfer member which is pressed against the image carrier while being driven to rotate. The present invention relates to an image forming apparatus for secondary-transferring an image onto a recording medium pressed against an intermediate transfer member by a pressing rotator.

[0002]

2. Description of the Related Art A conventional image forming apparatus using an electronic copying system, which is used in an analog copying machine, a digital copying machine, a laser printer, a facsimile, or the like, generally converts a toner image formed on an image carrier directly. To a recording medium,
It is configured to fix this. On the other hand, there has been proposed an image forming apparatus of a type in which a toner image on an image carrier is temporarily transferred to an intermediate transfer member once, and the toner image is secondarily transferred to a recording medium (for example, Japanese Patent Publication No. 46-41679).
And JP-A-59-17572.

[0003]

In such an image forming apparatus, as a method of secondary-transferring the toner image on the intermediate transfer member onto a recording medium, the toner image on the intermediate transfer member is heated by heating means. And a secondary transfer to a recording medium by melting the toner, and a secondary transfer of the toner image on the intermediate transfer body to the recording medium electrostatically, and heat-fixing the toner image on the recording medium by a fixing device. Although a method using a combination of the methods is conceivable, a heating unit is used regardless of which method is used, and therefore, the image carrier is heated by the heating means, and the temperature may increase. The image carrier is formed of, for example, a photoconductor which is charged to a predetermined polarity and an electrostatic latent image is formed by image exposure. However, if the temperature of the image carrier becomes excessively high, its charging characteristics deteriorate. I do. Further, there is also a problem that the toner is fused to the heated image carrier and the image finally formed on the recording medium is disturbed.

It is an object of the present invention to provide an image forming apparatus using an intermediate transfer member, which can prevent the image carrier from being excessively heated by a simple structure.

[0005]

According to the present invention, in order to achieve the above object, a toner image is formed on an image carrier that is driven to rotate, and the toner image is pressed against the image carrier while being driven to rotate. In an image forming apparatus for primary transfer to a transfer body, melting the toner of the toner image by heating means, and secondary transfer of the fused toner image to a recording medium pressed against the intermediate transfer body by a pressing rotator, The intermediate transfer body and the image carrier are supported so as to be able to contact and separate from each other, and the intermediate transfer body and the image carrier are pressed against each other at least at the time of the primary transfer, and when the intermediate transfer body and the image carrier are pressed against each other, An image forming apparatus that controls the heating unit so as not to operate the heating unit is proposed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an example of an image forming apparatus according to the present invention. The apparatus comprises a photosensitive drum 101 as an example of an image carrier and an intermediate transfer member 102 formed in a drum shape.
And a pressure rotating body configured as the pressure roller 103. In this example, the photosensitive drum 101 is located at the lowermost position, the intermediate transfer member 102 is located above the photosensitive drum 101, and the pressure roller 103 is located above the intermediate transfer member 102. Intermediate transfer member 1
02 operates from the retracted position shown by the solid line to the position shown by the broken line or the position shown by the dashed line, and the photosensitive drum 101
Alternatively, it can be pressed against the pressure roller 103.
The contact / separation operation will be described later.

The photoconductor drum 101 exemplified here is a drum-shaped organic photoconductor having relatively excellent pressure resistance and heat resistance, and the pressure roller 103 is a rigid roller made of, for example, aluminum. Alternatively, the outer surface may be covered with a compression-resistant resin. Instead of such a drum-shaped pressure rotating body, image carrier, or intermediate transfer body, a belt-shaped one can be used.

As will be described in detail later, a toner image is formed on the photosensitive drum 101, and this toner image is transferred at a portion indicated by the symbol A on the intermediate transfer member 102 occupying the position indicated by the broken line. You. This transfer is the primary transfer, and hereinafter, this portion A will be referred to as a primary transfer portion. The toner image primary-transferred onto the intermediate transfer member 102 is an example of a transfer medium fed between the intermediate transfer member 102 and the pressure roller 103 occupying a position indicated by a dashed line, as described later. Is transferred to the transfer paper 120 at the portion indicated by reference numeral B. This is the secondary transfer, and this part B
Is referred to as a secondary transfer unit.

Although the present invention can be applied to an image forming apparatus that exclusively forms a single color image, the image forming apparatus shown in FIG. 1 is configured to be capable of forming a multicolor image. The details of the configuration shown in FIG. 1 will be clarified while the operation is described below.

FIG. 2 is a time chart showing the basic operation of the apparatus. First, when the operator presses a print key not shown in FIG. 1, the main motor of the apparatus starts rotating (see FIG. 2). (1), (2)). When the CPU recognizes that the main motor has reached a steady rotation, the charging charger (scorotron charger) 104 provided around the photosensitive drum 101 starts operating ((3) in FIG. 2). Also, as shown in (25) of FIG.
An elevating motor (not shown) for raising and lowering the intermediate transfer body 102 operates, whereby the intermediate transfer body 102 which has been in the retracted position shown by the solid line in FIG. 1 is moved to the position shown by the broken line in FIG. As a result, the intermediate transfer member 102 comes into pressure contact with the photosensitive drum 101 as shown in FIG.

The pressure contact at this time is shown as "primary pressure contact" in FIG. 2 (27). In this pressure contact, the rise in the inclined straight line in the timing chart of FIG. This indicates that the transfer member 102 is initially separated from the photosensitive drum 101 and requires a certain period of time to complete the pressure contact between the two. Also, when they are separated from each other, they fall on a sloped straight line because it takes a certain time for the photosensitive drum 101 and the intermediate transfer body 102 to completely separate from the pressed state. Means.

When the photosensitive drum 101 and the intermediate transfer member 102 are pressed against each other as described above, a photosensitive motor clutch provided between the photosensitive drum 101 and the main motor is turned on, and the rotation of the main motor is started. Is the photosensitive drum 1
01, the photosensitive drum 101 starts rotating clockwise as indicated by the arrow in FIG. This clutch is shown as “photoconductor MC” in FIG. 2 (4).

Similarly, an intermediate transfer member motor clutch (intermediate MC) is provided between the intermediate transfer member 102 and the main motor, and another pressure roller is also provided between the pressure roller 103 and the main motor. Motor clutches (pressurized MC) are interposed, and these clutches are shown in (5) and (6) of FIG.
As shown in FIG. 1, the photoconductor motor clutch (photoconductor MC) is turned on at the same time as the photoconductor motor clutch, and the intermediate transfer body 102 and the pressure roller 103 start rotating in the directions indicated by arrows in FIG. At this time, the linear velocities of these peripheral surfaces are the same.

The photosensitive drum 101 and the intermediate transfer member 1
02, when the photosensitive drum 101 and the intermediate transfer member 102 are in pressure contact with each other, the intermediate transfer member motor clutch (intermediate MC) is disengaged, and the intermediate transfer member is rotated. You may make it rotate 102 along with rotation of the photosensitive drum 101.

As described above, the photosensitive drum 101 rotates clockwise in FIG.
Has already started operation, so the photosensitive drum 101
Is generated by the corona discharge of the charger 104.
It is uniformly charged to a predetermined polarity.

The photosensitive drum 101 charged as described above
Is exposed and scanned by a laser beam 106 modulated based on an image signal by a laser optical system 105, and an electrostatic latent image for a first color (in this example, a yellow image in this example) is formed on the surface of the photosensitive drum 101. (A yellow latent image) is formed. This is shown in FIG. 2 as “Y latent image formation” in (13).

A laser optical system 105 for imagewise exposing the surface of the charged photosensitive drum 101 with a laser beam 106 comprises a semiconductor laser (not shown), a polygon mirror, an fθ lens, and the like. To control the light emission of the semiconductor laser.

On the other hand, a developing device 110 is disposed around the photosensitive drum 101 as shown in FIG. 1, and the developing device 110 exemplified here contains yellow, magenta, cyan and black toners, respectively. Yellow developing unit 1
10Y, magenta developing device 110M, cyan developing device 110
C and a black developing unit 110 </ b> B, and these developing units are arranged along the moving direction of the photosensitive drum 101. These developing devices are selectively operated and used. Although the developing device 110 shown in FIG. 1 is a dry developing device, a wet developing device using a developing solution can be used instead.

As the toner used in each developing device, it is preferable to use a toner having a particle size of 5 μm or less in order to improve dot reproducibility, and it is desirable to use a toner having a narrow particle size distribution produced by a polymerization method.

As described above, when the yellow latent image formed on the photoreceptor drum 101 that is driven to rotate is passed through the yellow developing unit 110Y, the yellow latent image is visualized as a toner image by the yellow toner. At this time, the other developing devices 110M, 110C, and 110B do not perform the developing operation. The operation at this time is shown in FIG.
It is shown as

With the rotation of the photosensitive drum 101 and the intermediate transfer member 102, the photosensitive drum portion on which the yellow toner image has been formed as described above is the primary transfer in which the intermediate transfer member 102 and the photosensitive drum 101 are pressed against each other. When the image reaches the portion A, the yellow toner image on the photosensitive drum 101 is primarily transferred onto the intermediate transfer member 102 at this time. The toner image on the photosensitive drum 101 is primarily transferred onto the intermediate transfer body 102 pressed against the photosensitive drum 101 while being rotated.

The photosensitive drum 10 that has passed through the primary transfer section A
The toner remaining on the surface of the photosensitive drum 101
Is removed by a cleaning device 111 disposed around the device, and the surface is cleaned, and is subjected to a charge removing operation by a charge removing device (not shown). The primary transfer of the yellow toner image is referred to as “primary transfer” and “Y primary transfer” in (21) of FIG.
The cleaning of No. 01 is shown as “photoconductor cleaning” in (22) of FIG.

During such an operation, the intermediate transfer member 102 is rotating, and the yellow toner image primarily transferred to the surface of the intermediate transfer member 102 is transferred to the secondary transfer portion B and a cleaning device 112 for cleaning the intermediate transfer member 102. At this time, it is shown in FIG. 2 (28) as “secondary pressure contact” meaning pressure contact between the intermediate transfer body 102 and the pressure roller 103, and FIG.
As can be seen from FIG. 4), which is referred to as “intermediate cleaning” meaning the cleaning operation of the intermediate transfer member 102, the pressure roller 103 does not contact the intermediate transfer member 102, and the cleaning device 112 does not operate. Further, since the cleaning roller 112a is separated from the intermediate transfer member 102, there is no possibility that the yellow toner image on the intermediate transfer member 102 is disturbed.

As described above, the surface of the photosensitive drum 101 which has been cleaned by the cleaning device 111 and has been subjected to the charge removing operation by the charge removing device is uniformly charged again by the charging charger 104 (FIG. 2 (3)). A magenta latent image for a magenta image is formed on the surface by the laser 106 from the laser optical system 105 ("M latent image formation" in FIG. 2 (15)). Subsequently, the magenta latent image is visualized as a magenta toner image by the selected magenta developing device 110M instead of the yellow developing device 110Y ("M development" in FIG. 2 (16)). This magenta toner image is also transferred to the primary transfer portion A with the rotation of the photosensitive drum 101.
, And the primary transfer is performed on the intermediate transfer member 102 from above the yellow toner image (“M primary transfer” in FIG. 2 (21)). The toner remaining on the photosensitive drum 101 after the primary transfer is also cleaned by the cleaning device 111 ((22) in FIG. 2), and the surface of the drum 101 is subjected to a charge removing operation.

Similarly, a cyan latent image for a cyan image and a black latent image for a black image are sequentially formed on the photosensitive drum 101 (“C latent image formation” in FIG. (“B latent image formation” in (19)), these latent images are sequentially visualized as toner images of the respective colors by the cyan developing unit 110C and the black developing unit 110B (see “C developing in FIG. 2 (18)”). , "B development" in (20)), and these toner images are primarily transferred onto the intermediate transfer body 102 in order from the top of the previously transferred toner image ("C primary transfer" in FIG. 2 (21)). And "B primary transfer"). In this way, a full-color toner image is formed on the intermediate transfer member 102.

When the arrangement of each element such as the photosensitive drum 101, the intermediate transfer member 102, and the pressure roller 103 is changed, the start timing of the formation of the electrostatic latent image and the start of the developing operation is changed in accordance with this. Needless to say, it is necessary to change from the one shown in.

When all of the primary transfer is completed, the intermediate transfer member 102 is separated from the photosensitive drum 101 ((27) in FIG. 2) by the operation of the lifting / lowering motor ((25) in FIG. 2). As shown, it moves toward the pressure roller 103 and presses against the pressure roller 103 (see FIG. 4). This pressure welding is shown in FIG. 2 as “secondary pressure welding” at (28).

The timing of releasing the primary transfer portion pressure contact for separating the intermediate transfer member 102 from the photosensitive drum 101 is determined by the timing at which the primary transfer of the toner image on the photosensitive drum 101 to the intermediate transfer member 102 is completed. In the non-image area of
It is preferable that the toner image on the intermediate transfer member 102 is not disturbed.

The leading end of the full-color toner image formed on the intermediate transfer member 102 reaches the secondary transfer portion B as the intermediate transfer member 102 rotates. The paper feed motor clutch (paper feed MC) provided between the paper feed roller 113 and the paper feed roller 114 is turned on ((8) in FIG. 2), and the paper feed roller 114 is turned clockwise in FIG. Rotate. As a result, the transfer paper 120 accommodated in the paper supply unit 113 is fed to the left in FIG. 1, and as shown in FIG.
Transported to

The registration roller 115 is also connected to the main motor via a registration motor clutch (registration MC). Immediately after the main motor starts to rotate as described above, the registration roller 115 is connected to the registration motor as shown in FIG. The motor clutch (resist MC) is turned on, the resist roller 115 rotates, and then the clutch is turned off.
When the leading end of the transfer paper 120 reaches the registration roller 115, the registration roller 115 is stopped.

Subsequently, at the timing when the full-color toner image on the intermediate transfer member 102 and the transfer paper 120 can be aligned, the registration motor clutch (registration MC) is turned on, and the registration roller 115 starts rotating ((7) in FIG. 2). ), The transfer paper 120 is transported to the secondary transfer section B.

On the other hand, the leading end of the transfer paper 120 is
, The intermediate transfer member 102 is pressed against the pressure roller 103 as described above, and the transfer paper 120 is moved to the secondary transfer portion between the intermediate transfer member 102 and the pressure roller 103 pressed against each other. B, and is transported to the left in FIG. The intermediate transfer member 102 and the pressure roller 103 are pressed against each other in synchronization with the timing when the leading end of the transfer paper 120 reaches the secondary transfer portion B between the intermediate transfer member 102 and the pressure roller 103. The problem that the upper toner image is transferred to the pressure roller 103 can be prevented.

As described above, when the transfer paper 120 is in the secondary transfer portion B
2, the full-color toner image on the intermediate transfer body 102 is secondarily transferred onto the transfer paper 120 (see (2) in FIG. 2).
3)). In this manner, the toner image on the intermediate transfer member 102 is secondarily transferred to the transfer paper 120 pressed against the intermediate transfer member 102 by the pressure roller 103. The toner remaining on the intermediate transfer body 102 after the secondary transfer of the toner image is removed by the cleaning device 112 ((24) in FIG. 2). The cleaning device 112 will be described in detail later.

Next, the transfer paper 120 is transported by a transport belt 122 driven in the direction of the arrow and a pair of rotating paper discharge rollers 1.
The sheet is conveyed by the printer 17 and is discharged to the paper discharge unit 119. A discharge motor clutch (discharge MC) is also interposed between the conveyance belt 122 and the discharge roller 117 and the main motor, and this clutch is turned on immediately after the rotation of the main motor is started. 122 and the paper discharge roller 117 are driven to rotate, and the transfer paper 120 is rotated as described above.
Is transported to the paper discharge unit 119 ((9) in FIG. 2).

When the secondary transfer is completed, the elevating motor operates ((25) in FIG. 2), and the intermediate transfer member 102 descends.
It is separated from the pressure roller 103 and the pressure contact of the secondary transfer portion B is released ((28) in FIG. 2). In this way, the intermediate transfer member 102 moves to the retreat position shown by the solid line in FIG.

Here, the "intermediate transition" shown in FIG. 2 (26) means that the intermediate transfer member 102 moves from its retracted position to a position where it comes into pressure contact with the photosensitive drum 101, and the pressure roller 1
The timing at which the intermediate transfer member moves to a position where the intermediate transfer member is pressed against the time axis 03 is shown in the timing chart in this timing chart. 102 indicates that the intermediate transfer member 102 moves toward the photosensitive drum 101 and presses against the photosensitive drum 101 and shifts to the plus side (upper side in FIG. 2). Move to the roller 103
It shows that it is pressed against.

Further, in this embodiment, when the intermediate transfer member 102 performs the contact / separation operation with respect to the photosensitive drum 101 or the pressure roller 103, the cleaning device 11 for the intermediate transfer member 102 is used.
2, a heater 121 and a temperature sensor 123, which will be described later,
As shown by a broken line and a dashed line in FIG.
Works with 2.

At the exit of the paper output unit 119, a paper output unit exit sensor (not shown) is provided.
When the discharge of the transfer paper 120 is confirmed and the cleaning of the intermediate transfer body 102 is completed, the main motor, the charging charger, the resist MC, the paper discharge MC, the photoconductor MC, and the intermediate MC are cut off. .

A registration detection sensor 116 is disposed at a position on the near side of the registration roller 115 in the transfer paper transport direction, and the leading end of the transfer paper 120 transported from the paper supply unit 113 is used as a sensor as described above. After a predetermined time (t seconds) from the detection by 116, the sheet feeding motor clutch (sheet feeding MC) is turned off ((10) and (8) in FIG. 2). In this case, the leading end of the registration roller 1
The transfer paper 120 abutting on the transfer paper 15 can be slightly curved, and in this state, when the registration roller 115 is rotated to start feeding the transfer paper 120 to the secondary transfer portion B, skew occurs on the transfer paper. Without using this, the intermediate transfer body 1
02 can be conveyed with good timing in accordance with the leading edge of the toner image. The timing at which the paper feed motor clutch (paper feed MC) is turned off, that is, the time t, is set to
Of course should be set appropriately according to the transport speed.

The transfer paper 120 is supplied from the paper supply unit 113 by the rotation of the paper supply roller 114. The vibration during this operation adversely affects the electrostatic latent image formed on the photosensitive drum 101. When there is a possibility that the transfer sheet 120 may be provided, an operation sequence in which the transfer paper 120 is not fed during the formation of the electrostatic latent image may be set.

In the timing chart of the press-contact of the secondary transfer section shown in FIG. 2 (28), the intermediate transfer member 10 that rises with a straight line having an inclination during the press-contact operation is shown.
2 is initially separated from the pressure roller 103, it takes a certain time for them to finish pressing, and when the pressing is released, it falls down with a straight line having an inclination.
This means that it takes a certain time for the intermediate transfer member 102 and the pressure roller 103 to completely separate from the pressed state.

It should be noted that the intermediate transfer member 10
When the secondary transfer of the toner image from the printer 2 to the transfer paper 120 is started, the pressing roller 103 and the intermediate transfer body 102
, That is, the secondary transfer section must be completely completed, and the photosensitive drum 101, the intermediate transfer member 102, and the pressure roller 103 rotate at the same peripheral linear velocity. It must be. From such a viewpoint, in this example, (6) in FIG.
As shown in (23) and (28), at the start timing of the secondary transfer, the pressure MC is turned off, the pressure roller 103 is freely rotatable, and the pressure roller 103 is rotated by the rotation of the intermediate transfer body 102. It is driven and rotated by the rotation of
The peripheral linear velocities of both are matched.

The above is an outline of the operation when a full-color final image is obtained on the transfer paper 120 by the image forming apparatus shown in FIG. 1. Next, the toner image on the photosensitive drum 101 is transferred to the intermediate transfer member. A method for primary transfer to 102;
A method of secondarily transferring the toner image on the intermediate transfer body 102 to the transfer paper 120 and fixing the secondarily transferred toner image will be described.

First, the method of secondary transfer will be described. In the image forming apparatus shown in FIG. 1, the surface of the intermediate transfer member 102 is made of a material having releasability from molten toner, for example, silicone rubber. In the vicinity of the intermediate transfer member 102, an infrared ray is provided in a region downstream of the photosensitive drum 101 and upstream of the secondary transfer portion B when viewed in the rotation direction of the intermediate transfer member 102. The heater 121 made of a halogen lamp, a nickel chromium alloy wire, a ribbon, or the like is arranged to face each other.

As shown in FIG. 5, the intermediate transfer member 102 has a thickness of 500 to 5000 μm and a rubber hardness of 3 on a drum base 102a made of a rigid material such as aluminum.
A sheet made of an elastic layer 102b having a thickness of 0 to 80 degrees, a conductive layer 102c having a thickness of 30 to 300 μm made of polyimide in which carbon black is dispersed, and an insulating layer 102d having a thickness of 10 to 300 μm is bonded with the elastic layer 102b inside. It is preferable to use one that has been used. Further, the intermediate transfer member 102
If the surface has irregularities larger than the size of the toner constituting the toner image, transfer omission may occur. Therefore, for example, when the toner has a substantially minimum particle size of 5 μm, it is desirable that the irregularities on the surface of the intermediate transfer member be 5 μm or less.

The above-mentioned heater 121 is turned on at the timing shown in FIG. 2 (29), and the full-color toner image formed of the four color toners formed on the intermediate transfer member 102 as described above is transferred to the secondary transfer portion B. Before reaching, the heater image is irradiated with heat rays from the heater 121. At this time, the black toner of the full-color toner image directly absorbs the heat rays and melts, and the chromatic color toner having the heat ray transparency is indirectly heated by the heat from the intermediate transfer body 102 heated by the heater 121. The four color toners of the full-color toner image are melted to have substantially the same viscosity.

When the thus fused full-color toner image reaches the secondary transfer portion B where the transfer paper 120 is present as the intermediate transfer member 102 rotates, the surface of the intermediate transfer member 102 Since the toner thus melted and fluidized exhibits releasability, the molten toner image on the intermediate transfer body 102 is effectively transferred to the transfer paper 120. Since the molten toner transferred to the transfer paper 120 permeates the transfer paper in this manner, the transferred toner image can be fixed to the transfer paper 120 simultaneously with the secondary transfer of the toner image.
Therefore, the transfer paper 120 after the completion of the secondary transfer may be discharged as it is without passing through the fixing device, and the configuration of the device can be simplified.

The heater 121 supplies energy required for secondary transfer of the toner image on the intermediate transfer member 102 and fixing of the toner image thus transferred to the toner image before the secondary transfer of the toner image. If the temperature of the toner at this time is too low, when the toner contacts the transfer paper 120, the temperature of the contact interface decreases, and the toner does not penetrate into the transfer paper, and transfer failure occurs. Conversely, if the temperature of the toner becomes too high, the transfer paper is likely to be deformed in various forms. For example, for a toner having a glass transition temperature of 60 ° C., it is desirable to set the temperature of the transfer paper 120 to about 60 to 120 ° C. By doing so, the transfer paper 120 The image can be transferred onto a transfer paper.

As described above, in this embodiment, the intermediate transfer member 102
The second transfer is performed by fusing the upper toner image. In this case, the heater 121 forms an example of a heating unit that melts the toner of the toner image on the intermediate transfer body. The toner image thus fused is secondarily transferred onto the transfer paper 120 pressed against the intermediate transfer body 102 by the pressure roller 103.

A heater is also provided inside the pressure roller 103, and this roller 103 is used as a heat roller.
3 is heated to a temperature equal to or higher than the glass transition temperature of the toner, and the transfer paper 120 is heated at the time of secondary transfer of the toner image, so that a sufficient amount of heat required for the toner is imparted.
A configuration in which a heater is provided inside the intermediate transfer member 102 may be employed. As described above, the heating unit that melts the toner of the toner image on the intermediate transfer member 102 can be configured in various modes.

As described above, in this example, the intermediate transfer member 10
2 is heated by a heater 121, melted and secondary-transferred onto the transfer paper 120, and is also fixed. Instead, the toner on the intermediate transfer body 102 is fixed. When the toner image is melted by the heater 121, the heating temperature is lower than that in the above-described configuration, and when the toner image is secondarily transferred to the transfer paper 120,
This may not be fixed on the transfer paper. In this case, the transfer paper that has passed through the secondary transfer portion B is passed through a fixing device (not shown), and thereby the toner image is thermally fixed on the transfer paper.

Alternatively, the toner on the intermediate transfer member 102 is not melted at all, but instead a bias voltage is applied to the pressure roller 103 to electrostatically transfer the toner image on the intermediate transfer member 102 to the transfer paper 120. , And the toner image may be secondarily transferred onto the transfer paper. In this case as well, the toner image on the transfer paper that has passed through the secondary transfer portion B needs to be thermally fixed by a fixing device.

The toner image on the intermediate transfer member 102 may be secondarily transferred to the transfer paper 120 by using the above-described melting of the toner and the application of the bias voltage to the pressure roller 103 in combination. .

When any of the secondary transfer methods is adopted, the intermediate transfer body 102 after the secondary transfer is cleaned by the cleaning device 112 as described above. In this embodiment, the cleaning device 112 When cleaning the residual toner on the intermediate transfer member 102 with the heat roller 112a having a low surface energy, the heat roller 1
The intermediate transfer body 102 is configured to be pressed against the peripheral surface of the intermediate transfer body 102 to melt the residual toner, transfer the toner to the roller 112a side, and clean the intermediate transfer body 102.

The heat roller 112a is made of, for example, a roller body made of aluminum coated with a material having high releasability, such as Teflon (registered trademark). 11
2a, the toner is scraped off by the rubber blade 112b pressed into contact with the cleaning device 11a.
Is stored in the second casing 112c.

When the toner image on the intermediate transfer member 102 is secondarily transferred to the transfer paper 120 without melting, the intermediate transfer member 1
An elastic blade or a magnetic brush that presses against the intermediate transfer body 102 as the cleaning device 112 for
Alternatively, an apparatus having a cleaning member such as a bias roller can be used.

Next, in order to primarily transfer the toner image on the photosensitive drum 101 to the intermediate transfer member 102, the intermediate transfer member 10
(2) an adhesive method in which a toner image is primarily transferred onto the intermediate transfer member 102 by using the adhesiveness of the surface of the intermediate transfer member 102, and a bias voltage is applied to the intermediate transfer member 102 so that the toner on the photosensitive drum 101 is An electrostatic method in which the toner image is electrostatically attracted to the surface and primary-transferred, and a first-color toner image formed on the photosensitive drum 101 is primarily transferred to the intermediate transfer member 102 by any one of the above-described methods. When the color toner image is primarily transferred to the intermediate transfer member 102, the toner image already transferred on the intermediate transfer member 102 is heated by the heater 121 to melt the toner image, and the adhesive force of the toner image on the photosensitive drum 101 It is possible to use a fusion adhesion method in which a toner image is primarily transferred onto the intermediate transfer member 102, or a transfer method in which these are used in combination.

The primary transfer may be performed by using any of the above-described methods. However, if the surface of the intermediate transfer member 102 is made of a viscoelastic material such as silicone rubber as described above, the surface becomes The toner image on the photosensitive drum 101 can be adhesively transferred onto the intermediate transfer member 102 by utilizing this property.

When the toner image on the photosensitive drum 101 is electrostatically primarily transferred to the intermediate transfer member 102, for example, the conductive layer 102c of the intermediate transfer member 102 shown in FIG. 5 is insulated from the drum base 102a. In this state, a bias voltage may be applied to the conductive layer 102c during the primary transfer of the toner image.

When the surface of the intermediate transfer member 102 has elasticity as described above, the intermediate transfer member 102
And the photosensitive drum 101 are in close contact with each other, and a sufficient contact area and uniform pressure can be obtained between the photosensitive drum 101 and the photosensitive drum 101. Therefore, it is possible to prevent a non-uniform gap from being formed between the two and to prevent toner scattering. And a toner image having excellent density and dot reproducibility without density unevenness.
And thus on transfer paper.

In the above description, each toner image on the photosensitive drum 101 is primary-transferred sequentially to the intermediate transfer member 102 to form a full-color toner image in which the toner images are superimposed on the intermediate transfer member 102. Alternatively, a full-color toner image can be transferred onto the transfer paper 120 in a superimposed manner. In this case, the transfer paper 120 fed from the paper supply unit 113 is wound around the peripheral surface of the pressure roller 103 and is held by a clamper (not shown). Is primarily transferred onto the intermediate transfer member 102, and then the toner image is secondarily transferred as it is onto a transfer paper 120 wound around a pressure roller 103. In the secondary transfer, the toner of the toner image on the intermediate transfer body 102 is melted by the heater 121 and transferred to the transfer paper 120, or the toner image on the intermediate transfer body 102 is electrostatically transferred to the transfer paper 120. Transcribe. Subsequently, for the second and subsequent color toner images,
Each time this is primary-transferred onto the intermediate transfer body 102, the transfer paper 120 is secondary-transferred, and finally a toner image of each color is transferred to the transfer paper 1.
20 to form a full-color toner image. Thereafter, the transfer paper 120 is peeled off from the pressure roller 103 and is discharged to the paper discharge unit 119.

When the toner image is superimposed and primary-transferred onto the intermediate transfer body 102, and the secondary transfer is collectively performed on the transfer paper 120, the transfer paper 120 is also clamped to the pressure roller 103. The transfer paper 120 may be pre-heated, and the toner image on the intermediate transfer body 102 may be secondarily transferred onto the transfer paper 120. In this case, the operation timing of the transfer system of the transfer paper 120 is different from that shown in FIG.

As described above, it is appropriately selected whether the toner images are sequentially superimposed and transferred onto the transfer paper or the full-color toner image on the intermediate transfer body 102 is collectively transferred onto the transfer paper. An image forming operation can be performed in combination, and the combination is as follows.

Adhesion of the first color, adhesion of the second and subsequent colors, color overlap on the intermediate transfer body First color electrostatic, electrostatic of the second and subsequent colors, color overlap on the intermediate transfer body First color adhesion, electrostatic of the second and subsequent colors, color of the intermediate transfer body Overlay First color adhesive / electrostatic, Second color and later adhesive / electrostatic, Intermediate transfer body color overlay First color adhesive, Second color and later melt adhesive, Intermediate transfer body color overlay First color adhesive, Second color and later adhesive, Transfer paper color Overlay First color electrostatic, Second and subsequent colors, Color overlay on transfer paper

As described above with reference to FIGS. 1 and 2, when the toner image on the intermediate transfer member 102 is secondarily transferred onto the transfer paper 120, the tip of the full-color toner image on the intermediate transfer member 102 The transfer paper 120 is fed in a timely manner in accordance with the timing, but a paper feed failure occurs due to deterioration of the paper feed roller 114 and the like, and the transfer paper 120
May not be transported. In order to cope with such a transfer paper transport trouble, that is, a jam, the above-described registration detection sensor 116 is fixed for a predetermined time after the paper feed motor clutch (paper feed MC) is turned on and the paper feed roller 114 starts rotating. When the CPU does not detect the leading end of the transfer sheet, the CPU determines that the supply of the transfer sheet is defective, that is, a jam has occurred. FIG. 2 (10) shows the operation state of the registration detection sensor 116 when the transfer paper 120 is conveyed without causing a jam, and the jam detection timing of the transfer paper is shown as "jam 1". . The operation when such “jam 1” is detected will be described later.

On the other hand, the transfer paper 120 is
5, the transfer paper 120 is finally discharged to the paper discharge unit 119, but as shown in FIG. A paper ejection detection sensor 118 is provided.
Is also configured to detect the jam of the transfer paper 120. That is, the above-described registration detection sensor 1
If the paper ejection detection sensor 118 does not turn on after a predetermined time has elapsed since the front end of the transfer paper 120 was detected and turned on by the CPU 16, the CPU detects the transfer paper 120 from the registration roller unit to the paper ejection unit. It is determined that a jam has occurred. FIG. 2 (11) shows a paper ejection detection state when such a jam does not occur, and the above-described determination timing when a jam occurs is indicated as "jam 2". The operation when “jam 2” is detected will also be described later in detail.

As can be seen from the details described above, the intermediate transfer member 102, the photosensitive drum 101, and the intermediate transfer member 1
02 and the pressure roller 103 are supported so as to be able to contact and separate from each other. For this reason, for example, during standby other than during the image forming operation, the intermediate transfer body 102 is separated from the photosensitive drum 101 and is separated from the pressure roller 103. The intermediate transfer member 102 can be kept separated, the load applied to the surfaces of the photosensitive drum 101, the intermediate transfer member 102, and the pressure roller 103 can be reduced, and the life can be prolonged. The load on the drive shaft can be reduced.

Further, as in this embodiment, the photosensitive drum 101
The toner images of different colors are sequentially transferred onto the intermediate transfer body 102, and the toner images are sequentially and primarily transferred onto the intermediate transfer body 102. When the toner image is secondarily transferred to the transfer paper 120, the intermediate transfer body 102 and the intermediate transfer body 102 are also added during the primary transfer. Since the pressure roller 103 is separated and the photosensitive drum 101 and the intermediate transfer member 102 can be separated from each other during the secondary transfer, the toner image on the intermediate transfer member 102 is The problem of shifting to the drum 101 can be prevented.

At this time, as is apparent from the detailed description above, the photosensitive drum 101 and the pressing roller 103
Are rotatable but supported in a fixed position,
The intermediate transfer member 102 is rotatable and movably supported so as to be in contact with and separate from the photosensitive drum 101 and the pressure roller 103.
02 is pressed against the photosensitive drum 101 and the intermediate transfer member 102 is pressed against the pressing roller 103 via the transfer paper 120 at least during the secondary transfer. , And intermediate transfer member 1
02 and the pressure roller 103 can be moved toward and away from each other by a very simple mechanism. Each element 10
Only the intermediate transfer member 102 of these elements is moved in order to contact and separate 1, 102 and 103.

Conventionally, it has been generally considered that at least two of the three elements, that is, the photosensitive drum, the intermediate transfer member, and the pressure roller, are movably supported, and the respective elements are brought into and out of contact with each other. Therefore, the contact / separation mechanism had to be very complicated, and the disadvantage of increasing the cost of the image forming apparatus was unavoidable. However, according to the above configuration, such a problem could be easily solved. You can do it.

As described above, when the intermediate transfer member 102 moves toward and away from the photosensitive drum 101 and the pressure roller 103, the toner image on the intermediate transfer member 102 is secondarily transferred to the transfer paper 120. The cleaning device 112 for cleaning the surface of the intermediate transfer body 102 after the
02, and in this example, the heater 121 and the temperature sensor 123 shown in FIG. 1 also move together, so that the overall configuration can be further simplified.

For example, as shown in FIGS. 3 and 4, the rotating shaft 202 of the intermediate transfer member 102 and the cleaning device 11
2, and both ends in the longitudinal direction of the temperature sensor 123 and the heater 121 are supported by a pair of common support plates 1, respectively, and left and right ends of each support plate 1 in the drawing are guided by guide rails 2 and 3 extending vertically. A rack 4 is integrally provided at one end of the support plate 1 slidably, and the rack 4 is meshed with a pinion 5 rotatably supported by the image forming apparatus main body. In order to move the intermediate transfer member 102 toward and away from the photosensitive drum 101 and the pressure roller 103, the intermediate transfer member 1
In order to move the support plate 1 up and down, the pinion 5 is driven to rotate by operating an elevating motor ((25) in FIG. 2) not shown in FIGS. Let it. In this manner, the intermediate transfer member 102 can be moved up and down together with the cleaning device 112, the temperature sensor 123, and the heater 121, and as shown in FIGS.
1 or the pressure roller 103, or the intermediate transfer body 102 can be moved to a retracted position shown by a solid line in FIG.

As described above, the intermediate transfer member 102 and the photosensitive drum 101, or the intermediate transfer member 102 and the pressure roller 103 can be moved toward and away from each other by a very simple contact / separation mechanism.

In the image forming apparatus shown in FIG. 1, the toner image on the intermediate transfer body 102 is
Is configured to apply thermal energy to the toner image on the intermediate transfer body 102 by the heater 121 for the purpose of secondary transfer to the toner image. However, when such a fusion secondary transfer method is not adopted, as described above, In addition, it is necessary to fix the toner image secondarily transferred to the transfer paper 120 on the transfer paper by the heat of the fixing device. As described above, since the heat source exists in the image forming apparatus main body regardless of which method is adopted, if the heat source is left as it is, the photosensitive drum 10 is excessively heated, and the charging characteristic thereof is deteriorated. Therefore, there is a possibility that the toner is fused on the photosensitive drum 101.

In order to prevent such a problem, in this embodiment, as shown in FIG. 1 and described above, the photosensitive drum 101 is located below the intermediate transfer body 102 and the pressure roller 103, The toner image on the photosensitive drum 101 is primarily transferred to an intermediate transfer member 102 located above the photosensitive drum 101.

With this configuration, the heater 121 serving as a heat source
All of the intermediate transfer member 102 heated by the heater, the fixing device, and the heater 121 are located above the photosensitive drum 101, and the heat radiated therefrom escapes upward. Can be prevented. In this way, with the extremely simple configuration of setting the position of the photosensitive drum 101, the photosensitive drum 101 can be protected from heat, and its characteristics can be prevented from being lowered and the toner can be prevented from being fused.

The toner image on the intermediate transfer member 102 is
For example, it is melted by heating means including a heater 121,
1. An image forming apparatus for secondary-transferring the molten toner image onto a transfer sheet 120, as shown in FIG.
02 and the photosensitive drum 101 are supported so as to be able to contact and separate from each other, and at least at the time of the primary transfer, the intermediate transfer body 102 and the photosensitive drum 101 are pressed against each other.
As shown in (27) of FIG. 2, when the intermediate transfer body 102 and the photosensitive drum 101 are in pressure contact with each other, the heater is controlled so as not to operate the heater 121 as shown in (29) of FIG. Thus, the temperature rise of the photosensitive drum 101 can be suppressed more effectively.

That is, when the photosensitive drum 101 and the intermediate transfer member 102 are in pressure contact with each other and the heater 121 is turned on and the intermediate transfer member 102 is irradiated, the intermediate transfer member 102 is heated. Since the light is directly transmitted to the photoconductor drum 101 pressed against the transfer body 102, the temperature of the photoconductor drum 101 increases, and the above-described problem is likely to occur. On the other hand, as described above, the intermediate transfer member 102
If the heater 121 is turned off when the photosensitive drum 101 is pressed against the photosensitive drum 101, the temperature of the intermediate transfer member 102 can be prevented from rising, so that the temperature of the photosensitive drum 101 does not rise to an excessively high temperature, and the characteristics of the photosensitive drum 101 deteriorate. Also, the fusion of the toner to the photosensitive drum 101 can be effectively prevented.

In the example shown in FIG. 2, (21), (2)
As shown in 7) and (29), the primary transfer of the toner image on the photosensitive drum 101 to the intermediate transfer member 102 is completed, and after the intermediate transfer member 102 is separated from the photosensitive drum 101,
The heater 121 is turned on to start applying thermal energy to the toner image on the intermediate transfer member 102, and the intermediate transfer member 10
After the transfer of the second toner image onto the transfer paper 120, the heater 121 is controlled so that the heater 121 is turned off.
The overheating of the photosensitive drum 101 is prevented.

Further, in the above-described configuration in which the toner image on the intermediate transfer member 102 is melted by a heating means such as a heater 121 and the toner image is secondarily transferred to the transfer paper 120, the surface temperature of the intermediate transfer member 102 If the image forming operation is interrupted when the temperature of the surface of the intermediate transfer body 102 becomes equal to or higher than a predetermined value is detected by the detecting unit, and the temperature detecting unit detects that the surface temperature of the It is possible to more reliably prevent the deterioration of the characteristics and the problem that the toner is fused to the photosensitive drum 101, thereby protecting the photosensitive drum 101.

The above-mentioned temperature sensor 123 constitutes an example of such a temperature detecting means. The temperature sensor 123 includes, for example, a thermocouple, a resistance temperature detector, an infrared sensor, and the like. As shown in FIG. 1, the intermediate transfer member 10 is arranged so as not to disturb the toner image on the intermediate transfer member 102.
2 are arranged opposite to each other in a non-contact state. Or,
The temperature sensor may be brought into contact with the surface of the intermediate transfer member outside the region where the toner image is formed on the intermediate transfer member 102, or may be brought into contact with the inside of the intermediate transfer member 102.

In general, the amount of heat radiated at both ends of the intermediate transfer member 102 is larger than that at the center in the axial direction, and the surface temperature of the intermediate transfer member 102 varies in the axial direction. The amount of heat energy supplied to both ends of the intermediate transfer member 102 is made larger than that at the center portion so that the temperature of the entire intermediate transfer member 102 can be correctly detected by the temperature sensor 123, or the overall surface temperature of the intermediate transfer member 102 And the temperature at the place where the temperature sensor 123 detects the temperature, and corrects the
It is desirable to be able to detect the second temperature.

As shown in FIG. 6, the signal of the temperature sensor 123 for detecting the surface temperature of the intermediate transfer member 102 is inputted to a comparing means such as the comparator 6, and the output signal of the comparator 6 is inputted to the CPU 7. I do. The reference value of the comparator 6 is set, for example, to such a value that the characteristics of the photosensitive drum 101 do not deteriorate or that the toner does not fuse to the photosensitive drum 101. Sensor 12
3 are compared.

When the CPU 7 determines from the output of the comparator 6 that the surface temperature of the intermediate transfer member 102 has reached a predetermined temperature or higher, the image forming operation is interrupted by a command from the CPU 7. That is, when the heater 121 is turned off, the photosensitive drum 101 and the intermediate transfer member 102 are separated from each other when they are in pressure contact, and when the intermediate transfer member 102 is in pressure contact with the pressure roller 103, the pressure contact is also performed. Then, the intermediate transfer member 102 is brought to the retracted position. At this time, if the transfer paper 120 is present in the secondary transfer portion B, the transfer paper 120 is discharged to the paper discharge portion 119, and then the intermediate transfer body 102 and the pressure roller 103 are separated. After that, the conveyance belt 122 and the paper discharge roller 117 are also stopped, and the operations of the registration roller 115 and the paper feed roller 114 are also interrupted.

However, the photosensitive drums 10 separated from each other
1. Regarding the rotation of the intermediate transfer member 102 and the pressure roller 103, it is preferable to continue the rotation and cool them as early as possible.

As described above, the temperature of the intermediate transfer member 102 is always detected by the temperature sensor 123,
When the temperature sensor 123 detects that the surface temperature of the photosensitive drum 101 and the temperature of the photosensitive drum 101 have increased,
By interrupting the image forming operation, the photosensitive drum 1
01 can be surely prevented from deteriorating its properties and fusing the toner.

When the temperature sensor 123 detects that the surface temperature of the intermediate transfer member 102 has fallen and the photosensitive drum 101 can be prevented from overheating, the image forming operation is restarted by a command from the CPU 7. .

Here, an apparatus capable of cooling the intermediate transfer body 102 is provided by providing a fan inside the image forming apparatus main body, providing a heat pipe to the intermediate transfer body 102 and circulating a coolant through the heat pipe. When it is detected that the surface temperature has become equal to or higher than the predetermined value, the cooling device is used to positively cool the intermediate transfer body 102, so that the photosensitive drum 101 can be more reliably heated from heat. In addition to the protection, the image forming operation can be restarted at an early stage.

By the way, in the image forming apparatus shown in FIG. 1, when the transfer paper is transportable as described above, that is, when a jam occurs, as shown in FIG. 2 by "jam 1" and "jam 2". , Is configured to detect the jam. When such a jam of the transfer paper is detected, the fact is displayed on the display section of the image forming apparatus main body.Conventionally, the operation of the entire image forming apparatus is stopped simultaneously with the detection of the jam, The image forming operation has been stopped. When the operator removes the jammed paper, confirms the removal, and satisfies various conditions for forming an image, the apparatus waits for a print start signal.

However, if the operation of the image forming apparatus is stopped at the same time as the occurrence of the jam and the rotation of the photosensitive drum 101 and the intermediate transfer member 102 is stopped, a part of the photosensitive drum 101 becomes high temperature. The intermediate transfer member 102 is stopped while being opposed to the heated intermediate transfer member 102, so that a large amount of heat is transmitted from the intermediate transfer member 102 to this portion, and the photosensitive drum 101 is heated in a state where the photosensitive drum 101 is locally frayed. In this case, not only the charging characteristics of the photosensitive drum 101 may be reduced, but also the surface of the photosensitive drum 101 may be damaged.

Therefore, in this example, when the jam of the transfer paper 120 is detected, the photosensitive drum 101 and the intermediate transfer body 10
No matter what the state of pressure contact or separation between the pressure roller 2 and the pressure roller 103 is, the intermediate transfer member 102 is moved to the retracted position shown in FIG.
02, and the intermediate transfer member 102 and the pressure roller 103 are separated from each other, and the rotation of the photosensitive drum 101 and the intermediate transfer member 102 is not stopped. Is configured to continue rotating. After a lapse of a predetermined time, the photosensitive drum 101 and the intermediate transfer body 102 are stopped, and in this state, a jam is displayed on the display unit, and the fact of the jam is reported to the operator. Thus, the photosensitive drum 1
While rotating the intermediate transfer member 01 and the intermediate transfer member 102 for a predetermined time, they are cooled.

When the photosensitive drum 101 is rotated as described above, only a part of the photosensitive drum 101 does not remain facing the high-temperature intermediate transfer member 102, and the overheating of the photosensitive drum 101 can be prevented. In addition, by rotating the photosensitive drum 101 and the intermediate transfer member 102, they can be effectively cooled. By operating the cooling device described above, the intermediate transfer member 102 and the photosensitive drum 101 can be cooled more positively. Also, the intermediate transfer member 102
Is rotated, it is possible to prevent the transfer paper 120 that has caused the jam from being heated, and it is possible to prevent a problem due to excessive heat being applied to the transfer paper.

The photosensitive drum 101 and the intermediate transfer member 10
During the above rotation of 2, these are separated from each other,
Even if a toner image is formed on the intermediate transfer member 102, there is no problem that the toner image is reversely transferred to the photosensitive drum 101. Turning off the heater 121 and the like to stop the image forming operation when a jam is detected is the same as in the related art.

In this example, as described above, since the jam of the transfer paper 120 is detected at the timing of “jam 1” and “jam 2” shown in FIG. 2, these jams are detected. The operation at that time will be described below.

First, the detection of the jam 1 is to check whether or not the transfer paper 120 supplied to the secondary transfer section B is jammed. When the jam 1 is detected, the jam detection flag is set. (See (12) in FIG. 2), the jam is recognized, and the operation related to image formation is stopped. That is, the paper feed MC is turned off and the paper feed roller 11
4 is stopped, the heater 121 is turned off, and the intermediate transfer body 102 is turned off.
The heating operation of the upper toner is interrupted, the pressure MC is turned off, and the rotation of the pressure roller 103 is stopped. Further, the cleaning device 112 for the intermediate transfer member 102 does not operate, the cleaning operation for the intermediate transfer member 102 is not performed, the resist MC is not turned on, and the registration roller 115
Does not rotate. At the time of this jam detection, the photosensitive drum 101, the intermediate transfer body 102, and the pressure roller 103 are separated from each other.
This separated state is maintained, and the intermediate transfer body 102 and the pressure roller 103 do not come into pressure contact with each other.

During normal operation, first, the intermediate transfer member 102
The pressure roller 103, which is not in contact with the transfer paper 120, is controlled so as to be pressed against the intermediate transfer body 102 in accordance with the transfer of the transfer paper 120 ((27) in FIG. 2). When (jam 1) occurs, the intermediate transfer member 102
Therefore, the pressure contact between the two is prohibited so that the toner is not directly transferred to the surface of the pressure roller 103.
As described above, when the transfer paper 120 does not exist between the intermediate transfer body 102 and the pressure roller 103, the pressure roller 103
Is controlled so as not to press against the intermediate transfer member 102.

Although the image forming operation is stopped as described above, the photosensitive drum 101 and the intermediate transfer member 102 continue to rotate for a predetermined time even if the jam 1 is detected. And waits for the operator's operation. When the jammed transfer paper is removed by the operator and the CPU determines the fact, the image forming apparatus is started up and the image forming operation is continued by the operator pressing the print key. In this way, the operation can be continued without overheating the photosensitive drum 101.

On the other hand, when the aforementioned “jam 2” is detected, the operation related to the secondary transfer, that is, the resist MC,
The heater, the press contact of the secondary transfer unit, and the pressurized MC are all stopped or released, a jam detection flag is set, and the jam is recognized. However, also in this case, the photosensitive drums 1 separated from each other
01 and the rotation of the intermediate transfer member 102 continue, and the photosensitive drum 1
Allow 01 to cool.

At this time, since the secondary transfer is stopped halfway, the rear end portion of the toner image remains on the intermediate transfer member 102. Therefore, the rotation of the intermediate transfer member 102 is continued as described above, and the cleaning device 112 is operated to clean the intermediate transfer member 102. After the rotation of the photosensitive drum 101 and the intermediate transfer member 102 is stopped, the operator is notified of the occurrence of the jam and waits for the operation of the operator.

The fact that the jammed transfer paper has been removed is indicated by C.
When the PU determines, the image forming apparatus is started up and waits for the next operation by the operator. At this time, the state of the image forming apparatus main body is an initial state. However, the set value of the first image forming state,
For example, input data such as the number of copies, the magnification, and the copy size remain in the memory. Therefore, if the operator successively presses the print key, only the remaining number of copies before the occurrence of the jam is output.

Incidentally, in the image forming apparatus shown in FIGS. 1 and 2, it is detected whether or not the transfer paper 120 supplied to the secondary transfer portion B where the secondary transfer is performed has a transport trouble, that is, the jam is detected. Is detected after the primary transfer is completed and the intermediate transfer member 102 and the photosensitive drum 101 are separated from each other.
3 is press-contacted, that is, performed before the secondary transfer is performed. In other words, when the jam 1 is detected, the entire output image, that is, a full-color toner image in this example is already formed on the intermediate transfer member 102, and all the toner images on the photosensitive drum 101 are subjected to the intermediate transfer. The primary transfer to the body 102 has been completed.

By setting the detection timing of the jam 1 to such a timing, the cleaning device 1 for cleaning the photosensitive drum 101 even when the fine particle toner is used.
11 can be effectively reduced. The operation at this time will be described with reference to FIG.

As shown in FIGS. 7A, 7B and 7C, the formation of all toner images on the photosensitive drum 101 is completed, and the toner images are all primary-transferred on the intermediate transfer member 102. After the transfer is completed, it is checked whether or not the jam 1 has occurred. Here, when the jam 1 is not detected, the normal sequence described above is performed (FIG. 7D). When the jam 1 is detected, the image forming operation is stopped as described above (FIG. 7). (E)). However, in this example, the photosensitive drum 101 and the intermediate transfer body 102 are stopped after rotating them for a predetermined time.

Next, when the transfer paper jammed by the operator is removed and the CPU determines that the transfer paper has been removed (FIG. 7 (f)), the image forming apparatus is started up and the operator waits for the next operation. However, at this time, a full-color toner image is formed on the intermediate transfer member 102.

Here, for example, when the operator does not need the toner image formed on the intermediate transfer member 102, the operator performs the intermediate transfer for cleaning the toner image on the intermediate transfer member 102 on the operation section. An input operation is performed on a body cleaning switch (not shown). As a result, the intermediate transfer body 102 starts to rotate in the counterclockwise direction in FIG. 1, the heater 121 is turned on to melt the toner image on the intermediate transfer body 102, and the cleaning device 112 is activated to set the intermediate transfer body 102 The upper toner image is removed, and the surface is cleaned (FIGS. 7G and 7H). At this time, the photosensitive drum 101 and the pressure roller 103 are separated from the intermediate transfer member 102.

As described above, since the toner image on the photosensitive drum 101 is not cleaned, the cleaning device 11
1 can be reduced, and its life can be extended.
In addition, since the toner image on the intermediate transfer member 102 is melted and removed by the cleaning device 112, the cleaning device 11 is more effective than removing the powdery toner.
2 can be reduced, and shortening of the life of the cleaning device 112 can be prevented.

Conventionally, when a jam occurs, a toner image has been formed on the photosensitive drum. Therefore, after the jam paper is removed, the toner image on the photosensitive drum is cleaned and removed by the cleaning device, and the image is removed. Although the cleaning device for the photosensitive drum is configured to perform the forming operation, a heavy load is imposed on the cleaning device for the photosensitive drum, and the service life of the cleaning device may be shortened. Since all the toner images on the body drum 101 have been primarily transferred to the intermediate transfer body 102, the conventional problem does not occur.

On the other hand, instead of removing the toner image on the intermediate transfer member 102 by the cleaning device 112 as described above, unnecessary paper (miscopy paper or the like) generated in an office or the like is supplied to the secondary transfer portion B. The intermediate transfer body 10 melted by the heater 121 while the paper is pressed against the intermediate transfer body 102 by the pressure roller 103.
2 can be simultaneously fixed on the paper by secondary transfer ((i) and (j) in FIG. 7). At this time, the toner image on the intermediate transfer body 102 may be electrostatically secondarily transferred to the paper. After the transfer of the toner image onto the paper, the intermediate transfer member 102 is cleaned by the cleaning device 112.

As described above, when the toner image on the intermediate transfer member 102 is secondarily transferred to unnecessary paper and is discharged to the paper discharge portion 119, the load on the cleaning device 112 of the intermediate transfer member 102 can be further reduced. , It is possible to achieve a longer life. In addition, since the toner image is transferred to the originally discarded paper, the waste can be effectively used. A separate paper supply unit for storing unnecessary paper (miscopy paper) generated in the office is provided, and in the above-described operation, unnecessary paper is supplied from the paper supply unit and the toner image is secondarily transferred to the paper. It can also be configured as follows.

Also, an unused new transfer paper 120 is fed from the paper supply unit 113 shown in FIG. 1 to the secondary transfer unit B in exactly the same manner as described above,
The upper toner image is transferred, and the transfer paper 120 is transferred to the discharge unit 11.
9, the transfer paper can be used as a completed copy paper as it is, and wasteful consumption of toner can be prevented ((k) and (l) in FIG. 7).

After removing the transfer paper having a defective supply, the toner image formed on the intermediate transfer body 102 is secondarily transferred onto a newly supplied transfer paper (unnecessary paper or new paper). The cleaning device 1
12 can be effectively reduced.

When the intermediate transfer member 102 is cleaned as described above after the jammed paper is removed and various conditions for forming an image are satisfied, a print start signal is waited for. In addition to the cleaning of the intermediate transfer member 102, the photosensitive drum 101 may be cleaned by the cleaning device 111 if necessary. However, at this time, the toner image before the primary transfer is also left on the photosensitive drum 101. Is not formed, so that the load on the cleaning device 111 can be prevented from becoming excessive.

When the operator wants to transfer the toner image formed on the intermediate transfer member 102 to new transfer paper (unnecessary paper or new paper) and output it, the operator operates the operation unit of the image forming apparatus main body. By inputting an image output switch (not shown), a new transfer sheet is fed from the sheet feeding unit, and the toner image is secondarily transferred and fixed onto the transfer sheet at the same time, so that the transfer image can be output. At this time, the intermediate transfer body 10
Since it is necessary to feed a new transfer sheet at a timing when the transfer sheet matches the toner image on the second transfer member 2, a detector (not shown) for detecting the home position of the intermediate transfer member 102 is provided. It is desirable to detect the position and feed the transfer sheet at the timing when the leading edge of the toner image on the intermediate transfer member 102 and the leading edge of a new transfer sheet match.

Although not shown in FIG. 7, before the image forming operation is stopped when the jam 1 occurs, or at an appropriate time such as after the jam paper is removed, the intermediate transfer member cleaning switch is not operated, and The toner image on the intermediate transfer member 102 may be automatically melted, and the toner image may be cleaned by the cleaning device 112.

In the configuration shown in FIG. 1, the toner of the toner image formed on the
23, and the molten toner is secondary-transferred onto a recording medium pressed against the intermediate transfer body 102 by a pressure roller 103. Such a recording medium may be made of a paper material such as plain paper or a resin material. Are often used. For example, it is widely used to use a resin sheet for an overhead projector as a recording medium and form a final image thereon. Such a resin sheet generally has a large heat capacity. Therefore, in order to secondarily transfer the molten toner image on the intermediate transfer member 102 onto the resin sheet, the toner image is secondarily transferred onto the transfer paper 120 made of plain paper. It is necessary to apply a larger amount of thermal energy to the toner image formed on the intermediate transfer member 102 than when.

On the other hand, in the timing chart shown in FIG. 2, when the toner image on the intermediate transfer body 102 is secondarily transferred, the heater 123 applies the toner image to the intermediate transfer body 102 during one rotation. Although heat energy is applied, when a resin-made recording medium is used, the intermediate transfer member 10 is not applied by such heat energy application.
In some cases, it is difficult to reliably transfer the toner image on the recording medium 2 to a recording medium and fix the toner image at the same time.

Therefore, when the recording medium is made of resin, the intermediate transfer member 10 is maintained while the heater 123 is operated.
2 is rotated a plurality of times to apply sufficient thermal energy to the toner image on the intermediate transfer member 102 to melt the toner image. Then, the recording medium is fed, and the toner image on the intermediate transfer member 102 is transferred to the recording medium. It is advantageous that the transfer is performed next. In this way, a high-quality final image can be obtained regardless of the material of the recording medium.

As the recording medium, not only its material but also various thicknesses are used. However, in this type of conventional image forming apparatus, the pressure between the intermediate transfer member and the pressure roller is always constant. Since the recording medium is kept constant, when the recording medium is particularly thick, it is difficult to pass the recording medium between the intermediate transfer member and the pressure roller, and the image of the image secondary-transferred to the recording medium is deteriorated. There was a fear. If the pressure between the intermediate transfer member and the pressure roller is changed depending on the material of the recording medium and is not adjusted to an appropriate pressure, the image quality of the image may be degraded.

Therefore, in this embodiment, the pressure at which the intermediate transfer member 102 and the pressure roller 103 are pressed against each other is changed according to the thickness and the material of the recording medium, and an appropriate pressure is obtained according to each recording medium. It is configured as follows. For example, when a thick recording medium is used, the pressing force between the intermediate transfer body 102 and the pressure roller 103 is reduced so that the thick recording medium can surely pass between them. Specifically, when the intermediate transfer member 102 is pressed against the pressure roller 103, the rotation amount of the pinion 5 shown in FIGS. The power can be adjusted. In this manner, a high-quality image can be formed on a recording medium of any material and of any thickness. Further, the gap between the pair of registration rollers 115 or the gap for the pair of discharge rollers may be adjusted according to the thickness of the recording medium.

Although the example of the image forming apparatus capable of forming a color image has been described above, the present invention can also be applied to an image forming apparatus that exclusively obtains a monochromatic image. In this case, a one-color toner is formed on an image carrier. An image is formed, this is primarily transferred to an intermediate transfer member, and then this is secondarily transferred to a recording medium.

[0122]

According to the first aspect of the present invention, the image carrier can be protected from heat, and its characteristics can be prevented from deteriorating.
The life of the image carrier can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a timing chart showing an example of the image forming sequence.

FIG. 3 is an explanatory diagram illustrating a state in which an intermediate transfer member is pressed against a photosensitive drum.

FIG. 4 is an explanatory diagram illustrating a state where an intermediate transfer member is pressed against a pressure roller.

FIG. 5 is an enlarged sectional view of the intermediate transfer member.

FIG. 6 is a block diagram of one embodiment of the present invention.

FIG. 7 is a flowchart of one embodiment of the present invention.

[Explanation of symbols]

 102 Intermediate transfer member

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/14

Claims (1)

(57) [Claims] 1. A toner image is formed on an image carrier that is driven to rotate, and the toner image is primarily transferred to an intermediate transfer member that is pressed against the image carrier while being driven to rotate, and the toner of the toner image is heated by a heating unit. An image forming apparatus that secondary-transfers the melted toner image to a recording medium pressed against the intermediate transfer body by a pressing rotator, wherein the intermediate transfer body and the image carrier are supported so as to be able to contact and separate from each other. And
At least during the primary transfer, the intermediate transfer member and the image carrier are pressed against each other, and when the intermediate transfer member and the image carrier are pressed against each other, the heating device is controlled so as not to operate the heating device. Image forming apparatus.