JPH08254924A - Image recorder - Google Patents

Abstract

PURPOSE: To prevent the fluctuation of the rotation of an image carrier at the time of rushing and ejecting a paper sheet, in a toner image transfer region between the image carrier and a pressure roll. CONSTITUTION: This image recorder is provided with the pressure roll 8 which has a surface which is always pressed on the surface of the image carrier K in the toner image transfer region Q2 and rotated in the same direction as that of the surface of the image carrier K and transfers a toner image Ia to the paper sheet Si passing through the toner image transfer region Q2, a pressing means which presses a cleaning member on the surface of the pressure roll 8 and is capable of adjusting the pressing force and a pressing force control means for decreasing the pressing force of the pressing means the moment the leading edge of the sheet Si rushes into the toner image transfer region Q2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine or printer for recording an image by developing an electrostatic latent image formed on an image bearing member into a toner image, transferring the toner image onto a sheet and fixing it. The present invention relates to an image recording apparatus such as a facsimile, and more particularly to an image recording apparatus that uses a pressure roll to transfer a toner image on the image carrier to a sheet.

[0002]

2. Description of the Related Art Conventionally, the following technology (J01) is known as an image recording apparatus using the pressure roll. (J01) Japanese Patent Application Laid-Open No. 59-184385, Special Table Sho 60
Techniques described in Japanese Patent Laid-Open No. 500831, etc. These publications adopt a method of transferring and fixing a toner image developed on a recording medium drum onto a sheet by pressure, and therefore, an unfixed toner image electrostatically transferred onto the sheet. Compared to the type of electrostatic recording device that heat-fixes,
Further, it is possible to provide an image recording apparatus that consumes less energy because it does not use heat.

However, the technique of (J01) has the following problems. Problem of (J01) In the image recording apparatus of (J01), since it is necessary to crush the toner and transfer and fix the toner on the paper, a high pressure is applied by the pressure roll in the transfer fixing area. When a sheet rushes into this transfer / fixing area or is ejected from the transfer / fixing area, the torque acting on the drum-shaped image bearing member changes greatly at that moment, causing rotational fluctuation of the image bearing member. As a result, there is a problem that the electrostatic latent image written on the image carrier at that time is distorted.

[0004]

As a technique for avoiding the above problem (J01), the following technique (J0) has hitherto been used.
2) and (J03) are known. (J02) Technology described in JP-A-55-146469 This publication describes a method of providing a minute gap between an image carrier and a pressure roll. However,
With this technique (J02), it is difficult to keep the minute gaps unchanged. (J03) Technology disclosed in Japanese Patent Laid-Open No. 58-126561 In this publication, there is disclosed a method of adjusting the load in accordance with the timing of the sheet entering and discharging the toner image transfer area between the image carrier and the pressure roll. Has been described. However, the technique of (J03) has a problem that a high load of several hundreds kgf has to be directly controlled, resulting in cost increase.

Further, if the transfer fixing pressure is lowered, the rotational fluctuation of the drum-shaped image bearing member can be suppressed, but unless a toner capable of transfer fixing at a low pressure is developed, problems such as transfer failure and fixing failure may occur. Is clear. Also,
In an apparatus using such a pressure roll, if fogging occurs for some reason or if the paper jams and does not reach the toner image transfer area, toner adheres to the pressure roll and There is a problem that the back surface of the subsequent paper is stained (show-through).

In view of the above-mentioned circumstances, the present invention has the following problems. (O01) To prevent the rotational fluctuation of the image carrier at the time of the leading edge of the sheet or the passage of the trailing edge of the sheet in the toner image transfer area between the image carrier and the pressure roll without controlling the force. (O02) Prevent paper stains due to stains on the pressure roll.

[0007]

The present invention devised to solve the above problems will now be described. The elements of the present invention are to facilitate correspondence with the elements of the embodiments described later. Note that the reference numerals of the elements of the embodiments are enclosed in parentheses. Further, the reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate understanding of the present invention and not to limit the scope of the present invention to the embodiments.

(First Invention) In order to solve the above problems,
The image recording apparatus of the first invention of the present application has the following requirements: (Y01) moving image carrier (K)
Toner image forming devices (1 to 7) for forming a toner image (Ia) on the surface, (Y02) in the toner image transfer area (Q2), the image carrier (K) is constantly pressed against the surface of the image carrier (K). Has a roll surface that moves in the same direction as the surface,
A pressure roll (8) for transferring the toner image (Ia) onto the sheet (Si) passing through the toner image transfer area (Q2),
(Y03) A cleaning member (21) that contacts the surface of the pressure roll (8) to clean the surface of the pressure roll (8), and (Y04) presses the cleaning member (21) against the surface of the pressure roll (8). Pressing means (22 to 28 + M + P + V), (Y0
5) Paper feeding means (11 + 12) for supplying the paper (Si) to the toner image transfer area (Q2), (Y06) The pressing at the moment when the leading edge of the paper (Si) enters the toner image transfer area (Q2). The pressing means (22-28) is used to reduce the pressure.
+ M + P + V) pressing force control means (29-3)
2).

(Second Invention) An image recording apparatus according to the second invention of the present application is characterized by having the following requirements:
(Y01) The toner image (I
Toner image forming apparatus (1-7) for forming a), (Y02)
The image carrier (K) in the toner image transfer area (Q2)
The toner image (Ia) is formed on the sheet (Si) that has a roll surface that is constantly pressed against the surface and moves in the same direction as the surface of the image carrier (K) and that passes through the toner image transfer area (Q2).
, (Y03) a cleaning member (21) for contacting the surface of the pressure roll (8) to clean the surface of the pressure roll (8), and (Y04) a surface of the pressure roll (8) Pressing means (22 to 22) that can press the cleaning member (21) and adjust the pressing force thereof.
28 + M + P + V), (Y05) Paper feeding means (11 + 1) for feeding the paper (Si) to the toner image transfer area (Q2).
2), (Y07) The pressing force control for operating the pressing means (22 to 28 + M + P + V) so as to increase the pressing force at the moment when the trailing edge of the sheet (Si) passes through the toner image transfer area (Q2). Means (29-32).

[0010]

Next, the operation of the present invention having the above features will be described. (Operation of First Invention) In the image recording apparatus of the first invention of the present application having the above-mentioned characteristics, the toner image forming apparatus (1 to 7)
Form a toner image (Ia) on the surface of the moving image carrier (K). The roll surface of the pressure roll (8) is constantly pressed against the surface of the image carrier (K) in the toner image transfer region (Q2) and moves in the same direction as the surface of the image carrier (K), while the toner image transfer region is being moved. The toner image (Ia) is transferred onto the sheet (Si) passing through (Q2). The pressing means (22 to 28 + M + P + V) capable of adjusting the pressing force presses the cleaning member (21) against the surface of the pressure roll (8). When the toner adheres to the surface of the pressure roll (8), the cleaning member (21) removes the adhered toner.

The pressure roll (8) is in a braked state by the load received from the cleaning member (21). Therefore, whether the image carrier (K) is driven and the pressure roll (8) is driven by it, or the pressure roll (8) is driven separately, the rotation speed of the image carrier (K). Is slower than when the cleaning member (21) is not pressed against the surface of the pressure roll (8), and this rotation speed is the process speed.

In the sheet feeding means (11 + 12), the toner image (Ia) on the surface of the image carrier (K) is transferred to the toner image transfer area (Q).
2) Adjust the timing to move to paper (Si)
Is supplied to the toner image transfer area (Q2). Paper (S
The load torque (that is, the brake torque at the time when the leading edge of the sheet plunges) suddenly acts on the image carrier (K) due to the thickness of the sheet (Si) when the leading edge of i) plunges into the toner image transfer area (Q2). The rotational speed of the image bearing member (K) increases and tends to decrease. However, at the moment when the front end of the paper (Si) enters the toner image transfer area (Q2), the pressing force control means (29 to 32) causes the cleaning member (2).
The pressing means (22 to 28 + M + P + V) is operated so as to reduce the force for pressing 1) against the surface of the pressure roll (8). The decrease in the pressing force reduces the brake torque due to the pressing force acting on the image carrier (K). The decrease in the brake torque due to the pressing force acting on the image carrier (K) tends to increase the rotation speed of the image carrier (K). As a result, it is possible to offset the increase in the brake torque at the time when the leading edge of the sheet (Si) rushes into the toner image transfer area (Q2) when the leading edge of the sheet rushes into the toner image transfer area (Q2). It is possible to prevent a decrease in the rotation speed of the.

(Operation of the Second Invention) In the image recording apparatus of the second invention of the present application having the above-mentioned characteristics, when the rear end of the paper (Si) passes through the toner image transfer area (Q2), the image is formed. Paper (Si) between the carrier (K) and the pressure roll (8)
A gap corresponding to the thickness of is formed instantaneously. At this time, the load torque acting on the image carrier (K) (brake torque when passing the trailing edge of the paper) momentarily decreases, and the rotation speed of the image carrier (K) tends to increase. However, the pressing force control means (29 to 32) press the cleaning member (21) against the surface of the pressure roll (8) at the moment when the trailing edge of the paper (Si) passes through the toner image transfer area (Q2). Then, the pressing means (22 to 28 + M + P + V) is operated to increase the pressing force. Due to the increase in the pressing force, the brake torque due to the pressing force increases on the image carrier (K). The increase of the brake torque due to the pressing force acting on the image carrier (K) tends to reduce the rotation speed of the image carrier (K). As a result, the paper (Si)
It is possible to offset the decrease in the brake torque when the trailing edge of the sheet passes when the trailing edge passes through the toner image transfer area (Q2), and the rotational speed of the image carrier (K) when the trailing edge of the sheet passes. It is possible to prevent the rise of.

[0014]

EXAMPLES Examples of the present invention will now be described with reference to the drawings, but the present invention is not limited to the following examples. In order to facilitate understanding of the explanation below,
Cartesian coordinate axes X-axis, Y-axis, and Z-axis are defined in the directions of arrows X, Y, and Z that are orthogonal to each other in the drawing, and the arrow X direction is the front, the arrow Y direction is the left, and the arrow Z direction is the up. In this case, the X direction (front) and the opposite direction (-X direction) are backward,
The opposite direction (-Y direction) to the Y direction (left side) is the right side, and the opposite direction (-Z direction) to the Z direction (upper direction) is the lower side. The front (X direction) and the rear (-X direction) are referred to as the front-back direction or the X-axis direction, and the left (Y direction) and the right (-Y direction) are included in the left-right direction or the Y-axis direction. That is, the upper direction (Z direction) and the lower direction (−Z direction) are referred to as the vertical direction or the Z axis direction. Furthermore, in the figure, "○" is put in "○".
The one with "" means an arrow from the back of the paper to the front, and the one with "x" in "○" means an arrow from the front to the back of the paper.

(Embodiment 1) FIG. 1 is an overall explanatory view of Embodiment 1 of an image recording apparatus of the present invention. In FIG. 1, the image recording device U has a laser writing device U1. The laser writing device U1 includes a semiconductor laser oscillator 1 as a laser light source, and a laser beam L from the semiconductor laser oscillator 1.
On the image carrier (that is, the image carrier) K of the collimator lens 2 for condensing the light and collimating it, the polygon mirror 3 for deflecting the beam from the collimator lens 2 in the scanning direction, and the deflected laser beam L. It is composed of a convex lens 4 for irradiating an image on the surface, a cylindrical mirror 5 for correcting the surface tilt of the polygon mirror 3, and the like. The laser writing device U1 is connected to an image processing device (not shown) for sending an image information signal to the semiconductor laser oscillator 1.

Around the image carrier K, a charger (charging roller) 6 for uniformly charging the surface of the image carrier K is provided. An electrostatic latent image is written on the surface of the image carrier K charged by the charger 6 at the latent image writing position Q1 by the laser writing device U1.
The image carrier K is formed by depositing an amorphous silicon film on the surface of an aluminum cylindrical member to form a photosensitive layer. Further, around the image carrier K, the developing device 7 containing the pressure fixing toner, the developing roller 7a and the like in order from the latent image writing position Q1 toward the drum rotation direction, the image carrier by the developing device 7. A pressure roll 8 for transferring and fixing the toner image Ia formed on K onto a sheet (transfer material) Si.
, A cleaner 9 having a blade 9a for scraping off the toner for removing the residual toner Ic on the image carrier K, and a static eliminator for removing the residual charge on the image carrier K (static elimination). Rollers) 10 are provided respectively. The toner image forming apparatuses (1 to 7) are composed of the elements indicated by the reference numerals 1 to 7. The surfaces of the pressure roll 8 and the image carrier K are arranged so as to come into contact with each other with their axes slightly intersecting each other.

A sheet feed tray 11 that can be pulled out outward and inserted inward contains sheets Si. A paper feed roller 12 as a paper carry-out member is arranged above the paper feed tray 11. The paper feed tray 11 and the paper feed roller 12 constitute a paper feed means (11 + 12). The paper Si accommodated in the paper feed tray 11 is timed with the operation of the laser writing device U1.
The sheet is carried out by the sheet feeding roller 12 and conveyed to a region (toner image transfer region (Q2) or nip) Q2 where the pressure roll 8 and the image carrier K face each other. A chute member 13 is provided between the paper feed roller 12 and the toner image transfer area Q2. This chute member 1
3 is composed of a pair of upper and lower guide plates. When passing through the toner image transfer area Q2, the toner image Ia on the image carrier K is transferred onto the sheet Si and is fixed at the same time to form a fixed image Ib. The paper sheet Si on which the fixed image Ib is formed is discharged from the discharge roller 16 to the discharge tray H along the guide 14.

Next, referring to FIGS. 1 to 4, the image recording device U will be described.
The transfer device T will be described in detail. FIG. 2 is an explanatory diagram of a cleaning member on the surface of the pressure roll 8 and a means for pressing the cleaning member against the pressure roll 8 according to the first embodiment of the present invention. FIG. 3 is a detailed explanatory view of the cleaning member. FIG. 4 is an explanatory diagram of a hydraulic circuit of means for pressing the cleaning member against the pressure roll. <Figure 5> It is the operational explanation drawing of the same execution example 1.

In FIG. 1, X of the shaft 8a of the pressure roll 8 is
Both ends in the axial direction are rotatably supported by roll supporting arms 17. The roll support arm 17 is supported by a frame (not shown) of the image recording device U so as to be vertically swingable around a swing shaft 18. Further, the pressure roll 8 is pressed against the image carrier K with a predetermined pressure by a tension spring 19 provided between the roll support arm 17 and the frame of the image recording apparatus U. In FIGS. 2 and 3, the cleaning member 21 is made of felt fixed to the cylindrical surface of the pedestal 22 made of aluminum. The cylindrical surface of the pedestal 22 to which the cleaning member 21 is fixed is processed so as to have a curvature substantially the same as the curvature of the outer circumference of the pressure roll 8.

In FIGS. 1 and 2, both front and rear ends (both ends in the X-axis direction) of the pedestal 22 are swingable arms 2 capable of swinging up and down.
It is fixedly supported by 3, 24. Swing arms 23, 24
The left end portion (Y side end portion) is swingably supported by a frame (not shown) of the image recording apparatus U. Swing arm 2
Extendable hydraulic cylinders 26 and 27 are provided between the right ends (−Y side ends) of the frames 3 and 24 and the frame (not shown) of the image recording apparatus U. Hydraulic cylinder 26, 27
When is extended, the swing arms 23 and 24 swing upward, the cleaning member 21 rises, and is pressed by the pressure roll 8. At this time, the friction brake torque acts on the pressure roll 8, and the brake torque also acts on the image carrier K in pressure contact with the pressure roll 8. The pressing force of the cleaning members 21 by the hydraulic cylinders 26 and 27 is
The pressure roll 8 acts so as to press it against the image carrier K. The pressing force is for the purpose of causing a friction brake to act on the rotation of the pressure roll 8, and the tension spring 19
Is smaller than the force pressing the pressure roll 8 against the image carrier K.

2 and 4, each of the hydraulic cylinders 2
6, 27 are connected to the hydraulic pump P and the oil sump 28 via the pressure control valve V. The hydraulic pump P is rotatably driven in one direction by a motor M.
When the hydraulic pump P operates, the pressure oil causes the hydraulic cylinder 26,
The hydraulic cylinders 26 and 27 are extended by being supplied into the hydraulic cylinder 27. The hydraulic pressure in the hydraulic cylinders 26 and 27 is maintained at the pressure set by the pressure control valve V. Pressing means (2) for pressing the cleaning member 21 against the pressure roll 8 from the elements indicated by the reference numerals 22 to 28, P, V and M.
2 to 28 + M + P + V).

In the figure, an encoder 29 outputs a rotation speed detection pulse (that is, an encoder pulse) according to the rotation speed of the rotation shaft of the image carrier K. The encoder pulse is input to the microcomputer (microcomputer) 30. The microcomputer 30 outputs a drive control signal to the motor drive circuit 31 and the pressure control valve drive circuit 32 according to the input encoder pulse width (that is, the rotation speed of the image carrier K). That is, the microcomputer 30
In order to keep the rotation speed of the image carrier K constant, for example, when the encoder pulse width becomes short (that is, the image carrier K
The pressure control valve drive circuit 32 and the motor drive circuit 31 are operated so as to extend the hydraulic cylinders 26 and 27. At this time, the pressing force of the cleaning member 21 against the pressure roll 8 increases and the pressure roll 8
The brake that acts on is increased. Then, the brake also acts on the image carrier K pressed by the pressure roll 8. Then, the rotation speed of the image carrier K is reduced and maintained at a constant rotation speed. Reference numerals 29 to 3
The pressing force control means (29 to 32) is composed of the elements indicated by 2.

(Operation of First Embodiment) Next, the operation of the first embodiment of the image recording apparatus will be described. After the surface of the image carrier K is uniformly and positively charged by the charging roll 6 for precharging, a laser beam is emitted from the laser writing device U1 according to an image signal to form an electrostatic latent image. Next, the electrostatic latent image formed on the surface of the image carrier K is developed with the toner for pressure fixing by the developing device 7 to be visualized, and the toner image Ia is formed on the image carrier K. Pressure roll 8
Is disposed so as to cross the image carrier K,
A small slip occurs between the sheet Si and the image carrier K in the toner image transfer area Q2 where the image carrier K and the sheet Si face each other, and a high transfer rate can be obtained. Image carrier K
The upper toner image Ia is transferred onto the sheet Si by pressure and is fixed at the same time, so that a fixed image Ib is obtained. After the transfer, the residual toner Ic remaining on the image carrier K is mechanically scraped off by the blade 9a to complete one image recording cycle.

During the image recording cycle, the hydraulic cylinders 26 and 27 are expanded by the pressure oil sent from the pump P through the pressure control valve V which controls the pressure in the hydraulic cylinders 26 and 27 to a predetermined value. The swing arms 23, 2
4 has been pushed up. The swing arm 23,
The cleaning member 21 supported by 24 has a predetermined load (for example, 1 to 100 kgf, preferably 30 to 70 kgf).
It is pressed against the pressure roll 8 in f). The predetermined load value is the load value (usually several hundred Kgf) in the case of directly controlling the pressing force between the pressure roll and the image carrier in the conventional transfer fixing technique (see (J03) Ricoh application). It can be made smaller in comparison. Therefore, it is easier to control the load as compared with the related art.

FIG. 5A is a diagram showing the brake torque applied to the image carrier K by the sheet Si passing through the toner image transfer area Q2. FIG. 5B is a diagram showing the brake torque applied to the image carrier K by the pressure roll 8 pressed against the toner image transfer area Q2. FIG. 5C shows the toner image transfer area Q2.
FIG. 6 is a diagram showing a brake torque (total torque obtained by combining the brake torques of FIGS. 5A and 5B) applied to the image carrier K in FIG. FIG. 5D is an explanatory diagram of fluctuations in the rotation speed of the image carrier K when the total torque of FIG. 5C acts.

In FIG. 5A, at the moment when the leading edge of the sheet Si enters the toner image transfer area Q2, the leading edge of the thick sheet is drawn between the image carrier K and the pressure roll 8. At this moment, a torque that prevents the rotation of the image carrier K by the paper Si (a brake torque that rises when the leading edge of the paper rushes) acts. In this case, the rotation speed of the image carrier K decreases. At the moment when the trailing edge of the sheet Si passes the toner image transfer area Q2, the thick sheet between the image carrier K and the pressure roll 8 disappears, and at that moment, the image carrier K transfers the toner image. The brake torque is no longer received from the area Q2. That is, at the moment when the trailing edge of the sheet Si passes through the toner image transfer area Q2, the brake torque acting on the image carrier K becomes small. In this case, the rotation speed of the image carrier K increases.

When the rotation speed of the image carrier K decreases when the paper Si enters the toner image transfer area Q2, the decrease in the rotation speed is detected by the encoder 29 and the width of the encoder pulse becomes longer. At this time, the microcomputer 30
By controlling the pressure control valve drive circuit 32, the hydraulic cylinder 26,
The pressing force of 27 is reduced. At this time, as shown in FIG. 5B, the brake torque of the image carrier K due to the pressure of the pressure roll 8 decreases. Therefore, when the leading edge of the sheet is rushed, the combined brake torque that is increased by the leading edge of the sheet Si shown in FIG. The torque is as shown in FIG. 5C. In this case, as shown by the solid line in FIG. 5D, the image carrier K
The rotation speed of is first slightly decreased, then slightly increased, and then becomes a steady state. The two-dot chain line in FIG.
FIG. 6 is a diagram showing an example of variation of the image carrier K in the case where such control is not performed. As shown in FIG. 5D, the rotational speed fluctuation of the image carrier K can be reduced by performing the control (control of the pressing force of the cleaning member 21 against the pressure roll 8) as in the first embodiment. Becomes

When the trailing edge of the paper sheet Si passes from the toner image transfer area Q2, the rotation speed of the image carrier K increases, and the increase of the rotation speed is detected by the encoder 29, and the width of the encoder pulse becomes short. . At this time, the microcomputer 30
Controls the pressure control valve drive circuit 32 to control the hydraulic cylinder 2
Increase the pressing force of 6,27. At this time, as shown in FIG. 5B, the brake torque of the image carrier K due to the pressing force of the cleaning member 21 against the pressure roll 8 increases. Therefore, when the trailing edge of the sheet is passed, the brake torque decreased by the trailing edge of the sheet Si shown in FIG. 5A and the cleaning member 21 for the pressure roll 8 shown in FIG. 5B.
FIG. 5C shows the total torque obtained by combining the brake torques that increase due to the increase in the pressing force of. In this case, as shown by the solid line in FIG. 5D, the rotation speed of the image carrier K first slightly increases, then slightly decreases, and then becomes the steady state. Even when the trailing edge of the sheet is passed, the rotational speed fluctuation of the image carrier K is changed by performing the control (control of the pressing force of the pressure roll 8) as in the first embodiment, as in the case of the leading edge of the sheet Si. Can be reduced.

According to the control method described in the first embodiment, not only when the paper Si enters the front end and when the paper Si passes through the rear end, but also the minute fluctuations in the rotational speed of the image carrier K due to variations in the drive system are reduced. You can also When printing was performed with the configuration of this embodiment, good rotation was obtained in which the rotational fluctuation of the image bearing member K was small and the print misalignment due to the rotational fluctuation of the image bearing member K was below an allowable level. Further, when fogging occurs or when the paper sheet Si jams and does not reach the toner image transfer area Q2, the cleaning member 21 removes stains on the pressure roll 8 and the rear surface of the paper sheet Si thereafter. No stain (show-through) occurred on the.

(Second Embodiment) Next, a second embodiment of the image recording apparatus U of the present invention will be described with reference to FIG. In the description of the second embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 6 is an explanatory view of the second embodiment of the image recording apparatus U of the present invention, in which the cleaning member (the same cleaning member as the cleaning member 21 of the first embodiment) is replaced by a pressure roll (the same pressure roll as the pressure roll 8 of the first embodiment). FIG. 4 is an explanatory view of a hydraulic circuit of the means for pressing to FIG.
It is a figure corresponding to. The second embodiment differs from the first embodiment in the following points, but is configured similarly to the first embodiment in other points. In the second embodiment, instead of the encoder 29 of the first embodiment, a paper sensor 36 arranged on the upstream side of the toner image transfer area Q2 is used to detect passage of the front end and the rear end of the paper Si. There is. The detection signal of the paper sensor 36 is input to the microcomputer 30. The microcomputer 30 detects the time when the leading edge of the sheet Si enters the toner image transfer area Q2 and the time when the trailing edge of the sheet Si passes according to the detection signal of the sheet sensor 36, and at the detection time, the motor drive circuit 31 and the pressure control are performed. It is configured to operate the valve drive circuit 32.

(Operation of Second Embodiment) Next, the operation of the second embodiment of the present invention having the above-described structure will be described. Example 2
Then, the microcomputer 30 uses the detection signal of the paper sensor 36 to calculate the time of entry of the front end of the paper Si into the toner image transfer area Q2 and the time of passage of the rear end of the paper Si. Then, when the leading edge of the sheet Si enters and when the trailing edge of the sheet Si passes, the pressing force of the cleaning member 21 pressed against the pressure roll 8 is controlled in the same manner as in the first embodiment to control the brake torque acting on the pressure roll 8. By controlling
The brake torque that acts on the image carrier K pressed by the pressure roll 8 is controlled. In the second embodiment, as in the first embodiment, it is possible to reduce the fluctuation of the rotation speed of the image carrier K.

(Third Embodiment) Next, a third embodiment of the image recording apparatus U of the present invention will be described with reference to FIG. In the description of the second embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 7 is an explanatory diagram of a third embodiment of the image recording apparatus U of the present invention, in which the pressure roll 8 and the cleaning member 2 are used.
FIG. 3 is an explanatory view of a means for pressing 1 to the pressure roll 8 and is a view corresponding to FIG. 2 of the first embodiment. This Example 3 is
The present embodiment is different from the first embodiment in the following points, but is configured similarly to the first embodiment in other points. Instead of the hydraulic cylinders 26 and 27 of the first embodiment, tension springs 41 and 41 are used.
And solenoids 42 and 43 are used. A solenoid drive circuit 44 is used in place of the elements 28, 31 to 32, P, and M for driving the hydraulic cylinders 26 and 27 of the first embodiment.

(Operation of Third Embodiment) Next, the operation of the third embodiment of the present invention having the above-described structure will be described. Example 2
Is a brake torque acting on the pressure roll 8 by controlling the pressing force of the cleaning member 21 pressed against the pressure roll 8 by operating the solenoids 42 and 43 instead of the hydraulic cylinders 26 and 27 of the first embodiment. The brake torque acting on the image carrier K pressed by the pressure roll 8 is controlled by controlling the. In the third embodiment as well, the fluctuation of the rotation speed of the image carrier K can be reduced as in the first embodiment.

(Fourth Embodiment) Next, a fourth embodiment of the image recording apparatus U of the present invention will be described with reference to FIG. In the description of the fourth embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 8 is an overall explanatory view of the fourth embodiment of the image recording apparatus U of the present invention, and corresponds to FIG. 1 of the first embodiment. In the fourth embodiment, the cleaning member 2 is arranged so as to press the right side surface, not the lower surface of the pressure roll 8.

(Operation of Embodiment 4) Even if the cleaning member 21 is arranged on the side surface of the pressure roll 8 as in Embodiment 4, the same operation as that of Embodiment 1 arranged on the lower surface can be obtained. That is, by controlling the pressing force of the cleaning member 21 against the pressure roll 8 to control the brake torque acting on the pressure roll 8, the brake torque acting on the image carrier K pressed by the pressure roll 8 is controlled. be able to. That is, it is possible to reduce the fluctuation of the rotation speed of the image carrier K as in the first embodiment.

(Modifications) The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments, and is within the scope of the gist of the present invention described in the claims. Thus, various changes can be made. A modified embodiment of the present invention is illustrated below.

(H01) In the third embodiment, it is possible to use a cam instead of the solenoids 42 and 43 to adjust the displacement of the spring. (H02) In each embodiment, the pressing force of the cleaning member 21 against the pressure roll 8 does not necessarily need to be controlled to a continuous value. For example, pressing force (load) F = Fa (kg
Even with the simplest control in which f) and F = Fb (kgf, Fa> Fb) are taken, it is possible to reduce the fluctuation of the rotation speed of the image carrier K. (H03) The present invention can be applied only to one of the sheet entering and the sheet ejecting (passing the trailing edge). (H04) The present invention is an image carrier other than the image carrier K having the structure described in the first embodiment, in which a dielectric layer or a photoconductor layer is formed on the surface of a conductor base. Any surface can be applied as long as the surface has sufficient strength to withstand the pressure required for pressure transfer fixing. For example, the present invention is applied to a dielectric drum having an anodized surface of aluminum, and an image carrier having a structure in which an inorganic film such as silicon nitride or silicon carbide is deposited on the surface of aluminum by a method such as plasma CVD. It is possible. (H05) The present invention can be applied to an image recording apparatus using a charging device such as a corotron or a scorotron instead of the charging roll of the first embodiment. (H06) The present invention can be applied to an image recording device using an LED array, a liquid crystal light valve or the like instead of the laser writing device. (H07) In the present invention, instead of the image recording device that fixes the image carrier K to the sheet Si in the toner image transfer area Q2 at the same time as the transfer, only the transfer is performed by the pressure, and the heating means such as the fuser roll is used after the transfer. It can also be applied to an image recording device that is fixed again by. (H08) The present invention can also be applied to an image recording apparatus that transfers a toner image to an intermediate body and then transfers and fixes it on a sheet, instead of the image recording apparatus that transfers and fixes the image directly from the image carrier onto the sheet Si. (H09) In order to detect the entry of the sheet into the toner image transfer area Q2, it is possible to use the current detection of the image carrier drive motor, a strain gauge or the like.

[0038]

The image recording apparatus of the present invention described above can achieve the following effects. (E01) It is possible to reduce the fluctuation of the rotational speed of the image carrier when the front end of the sheet or the trailing edge of the paper passes in the toner image transfer area between the image carrier and the pressure roll. (E02) It is possible to prevent the stain on the paper due to the stain on the pressure roll.

[Brief description of drawings]

FIG. 1 is an overall explanatory diagram of a first embodiment of an image recording apparatus of the present invention.

FIG. 2 is an explanatory diagram of a cleaning member on the surface of the pressure roll 8 and a means for pressing the cleaning member against the pressure roll 8 in Embodiment 1 of the present invention.

FIG. 3 is a detailed explanatory view of the cleaning member.

FIG. 4 is an explanatory diagram of a hydraulic circuit of a unit that presses the cleaning member against a pressure roll.

5 is an explanatory view of the operation of the first embodiment, FIG. 5A is an image carrier K by the paper Si passing through the toner image transfer area Q2.
FIG. 5B is a diagram showing brake torque acting on the image carrier K by the pressure roll 8 pressed to the toner image transfer region Q2. FIG. 5C is a diagram showing brake torque acting on the image carrier K in the toner image transfer region Q2. FIG. 5D is a diagram showing a brake torque acting on K (total torque obtained by combining the brake torques of FIGS. 5A and 5B), and FIG. 5D is an explanation of fluctuations in the rotation speed of the image carrier K when the total torque of FIG. 5C is applied. It is a figure.

FIG. 6 is an explanatory view of a second embodiment of the image recording apparatus U of the present invention, and is an explanatory view of a hydraulic circuit of means for pressing the cleaning member against the pressure roll, corresponding to FIG. 4 of the first embodiment. FIG.

FIG. 7 is an explanatory view of a third embodiment of the image recording apparatus U of the present invention, and is an explanatory view of a cleaning member on the surface of the pressure roll 8 and a means for pressing the cleaning member against the pressure roll 8; 1. It is a figure corresponding to FIG.

FIG. 8 is an overall explanatory view of an image recording apparatus U according to a fourth embodiment of the present invention, and is a view corresponding to FIG. 1 of the first embodiment.

[Explanation of symbols]

K ... Image carrier, Ia ... Toner image, Q2 ... Toner image transfer area, Si ... Paper, 8 ... Pressure roll, 21 ... Cleaning member, (1-7) ... Toner image forming device, (11 + 12)
... paper feeding means, (22-28 + M + P + V) ... pressing means,
(29 to 32) ... Pressing force control means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Tanaka 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. An image recording apparatus having the following requirements, (Y01) a toner image forming apparatus for forming a toner image on the surface of a moving image carrier, and (Y02) the image in a toner image transfer area. A pressure roll that has a roll surface that is constantly pressed against the surface of the carrier and moves in the same direction as the surface of the image carrier, and that transfers the toner image onto a sheet that passes through the toner image transfer area; A cleaning member for contacting the surface to clean the surface of the pressure roll, (Y04) a pressing means for pressing the cleaning member against the surface of the pressure roll and adjusting the pressing force thereof,
(Y05) Paper feeding means for supplying paper to the toner image transfer area, (Y06) Pressing force for operating the pressing means so as to reduce the pressing force at the moment when the leading edge of the paper enters the toner image transfer area. Control means. 2. An image recording apparatus having the following requirements, (Y01) a toner image forming apparatus for forming a toner image on the surface of a moving image carrier, and (Y02) the image in a toner image transfer area. A pressure roll that has a roll surface that is constantly pressed against the surface of the carrier and moves in the same direction as the surface of the image carrier, and that transfers the toner image onto a sheet that passes through the toner image transfer area; A cleaning member for contacting the surface to clean the surface of the pressure roll, (Y04) a pressing means for pressing the cleaning member against the surface of the pressure roll and adjusting the pressing force thereof,
(Y05) paper feeding means for feeding a sheet to the toner image transfer area, (Y07) activating the pressing means to increase the pressing force at the moment when the trailing edge of the sheet passes through the toner image transfer area. Pressing force control means.