JPH06274051A - Method and device for recording image - Google Patents

Abstract

PURPOSE:To prevent a faulty image caused by rotational fluctuation by restraining the uneven rotation of an image carrier when a transfer medium rushes in by separating the image carrier from a pressure roll, and separating a press-contact part when the image is not formed by using a driving source for the image carrier. CONSTITUTION:An arm 136 rotatably supporting the pressure roll 5 is freely rocked with center at a rotary shaft 139, and the roll 5 is allowed to press- contact to a dielectric drum 1 functioning as the image carrier by a spring 137. Furthermore, a ratchet 140 keeping the roll 5 from press-contacting to the drum 1 by engaging with the arm 136 is provided at the tip of the arm 136. Before the image is formed on the drum 1, the roll 5 is moved by the driving force of the drum 1, so that a transfer nip part 16 is separated. In synchronization with timing that the transfer medium 6 advances into the transfer nip part 16 between the drum 1 and the roll 5, the separation of the transfer nip part 16 between the drum 1 and the roll 5 is released by the ratchet 140.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for transferring or transferring / fixing a toner image formed on an image bearing member onto a transfer medium by pressure, and particularly to prevent uneven rotation when the transfer medium enters. The present invention relates to an enabled image recording method and apparatus.

[0002]

2. Description of the Related Art Conventionally, as this type of image recording apparatus,
For example, Japanese Patent Laid-Open No. 56-116064 and Japanese Patent Publication No.
Some are disclosed in Japanese Patent No. 15953. These image recording devices form a toner image on an image bearing member such as a photosensitive drum or a dielectric drum by a predetermined means, and the toner image formed on the image bearing member and the image bearing member It is configured such that transfer or simultaneous transfer and fixing is performed by pressure on a transfer medium supplied to a pressure contact portion between the pressure roller and the pressure roller. Therefore, the image carrier and the pressure roll are pressed against each other at a pressure of 20 to 200 Kg / cm ² , or 18 to 125 Kg / cm.

As described above, in the case of the above image recording apparatus, since a predetermined pressure is applied between the image carrier and the pressure roll, the pressure contact pressure between these image carrier and the pressure roll is transferred. When the medium plunges into the pressure contact portion, the thickness increases by an amount corresponding to the thickness of the transfer medium. Therefore, when the transfer medium plunges into the pressure contact portion, the driving means for rotationally driving the image bearing member is temporarily subjected to a load and a torque fluctuation occurs, so that there is a temporary unevenness in the rotation of the image bearing member. Occur. At this time, since the image is continuously formed on the surface of the image carrier by the image forming unit, if the image carrier temporarily rotates, the image is distorted during the formation, and thus the image is formed. It has the problem of becoming the above defect.

Therefore, in order to solve this problem,
In order to reduce the pressure contact pressure between the image carrier and the pressure roll, and to suppress the rotational fluctuation of the image carrier when the transfer medium plunges,
It has been attempted to use toner for low pressure or attach a flywheel to the image carrier to suppress the rotational fluctuation of the image carrier.

However, when the toner for low pressure is used, there is a problem that the fusion of the toner is induced by the stress in the developing device, and when the flywheel is used, the image defect is caused. Although the effect of preventing the above can be expected sufficiently, there is a new problem that the device becomes large and heavy.

Therefore, when the transfer medium rushes into the pressure contact portion between the image carrier and the pressure roll without causing such fusion of the toner and increase in size and weight of the apparatus, a defect on the image is generated. As a technique that can be prevented, Japanese Patent Laid-Open No. 50-1600
39 and Japanese Patent Application Laid-Open No. 58-221877. These JP-A-50-1600
In Japanese Patent Laid-Open No. 39 and JP-A-58-221877, the pressurizing unit formed of the heating roll and the supporting roll is released when the paper is plunged, and the pressurizing unit is formed after the plunge. There is a description of a heat fixing device. When such a technique is applied to an image forming apparatus, the pressure contact portion formed by the image carrier and the pressure roll is released when the transfer medium enters, and the pressure contact portion is formed after the transfer medium is transferred. It can be expected to prevent the occurrence of image defects when entering the medium.

Further, Japanese Patent Laid-Open No. 61-90167 discloses an image forming apparatus which transfers a recording sheet by passing a recording sheet between an image carrier and a pressure roller which is pressed against the image carrier. A configuration is disclosed in which a buffer member is provided on at least one of the upstream side and the downstream side of a pressure transfer mechanism formed by a carrier and a pressure roller. It is also expected that the cushioning member can alleviate the impact when the recording sheet plunges into the pressure transfer portion formed by the image carrier and the pressure roller, and prevent the occurrence of image defects when the recording sheet plunges. it can.

[0008]

However, the apparatus according to the above-mentioned conventional proposal has the following problems. That is, like the former image recording apparatus of the apparatus according to the above proposal, the pressure contact portion formed by the image carrier and the pressure roll is released when the transfer medium is thrust, and the pressure contact portion is formed after the thrust. When configured, it is expected that the occurrence of image defects when the transfer medium enters can be expected, but power for pressing or releasing the image carrier and the pressure roll is taken from the drive means of the image carrier. In this case, due to the load, the image carrier also suffers from uneven rotation, and the image defect as described above occurs. Further, when the power for pressing or releasing the image bearing member and the pressure roll is taken from a driving unit different from the driving unit for the image bearing member, only the driving unit required for the driving unit is necessary. A new problem arises in that the size of the device is increased and the cost is increased.

On the other hand, like the latter image recording apparatus of the above proposed apparatus, a buffer member is provided on at least one of the upstream side and the downstream side of the pressure transfer mechanism formed by the image carrier and the pressure roller. It is expected that the occurrence of image defects at the time of entry of the recording paper can also be prevented when the configuration is provided, but in this case, at least one of the upstream side and the downstream side of the pressure transfer mechanism is Since it is necessary to provide a cushioning member in the
Since the pressure contact pressure between the image bearing member and the pressure roller is reduced even during the transfer of the recording paper, the pressure at the time of transfer or simultaneous transfer fixing is lowered, and a new image transfer cannot be performed. I have a problem.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is to prevent the rotation unevenness of the image carrier when the transfer medium enters from the image carrier and the pressure. While pressing by the separation of the rolls, the pressure contact part is separated by using the same drive source as the image carrier driving means,
An image recording method capable of reducing the size of the apparatus and preventing unevenness in rotation due to separation by performing the separation during non-image formation, and preventing image defects such as image distortion caused by rotational fluctuation. To provide the device.

[0011]

That is, according to the image recording method of the present invention, an electrostatic latent image is formed on the surface of an image carrier according to image information, and the electrostatic latent image is developed and developed. The image is transferred by pressure onto the transfer medium passing between the pressure contact portions of the pressure roller that is in pressure contact with the image carrier, or in the image recording method of simultaneously fixing the transfer, when an image is not formed on the image carrier, At least one of the image bearing member and the pressure roll is moved by the driving force from the driving unit that rotationally drives the image bearing member to separate the pressure contact portion, and thereafter, the transfer is performed between the image bearing member and the pressure contact portion of the pressure roll. The separation of the pressure contact portion is released by utilizing the urging force of the urging means for pressing the image carrier and the pressure roll in synchronism with the timing when the medium enters.

Further, the image recording apparatus according to the present invention forms an electrostatic latent image on the surface of the image carrier according to image information, develops the electrostatic latent image, and develops the developed image on the image carrier. In an image recording apparatus for transferring or simultaneously fixing by transfer onto a transfer medium passing between a pressure contact portion of a pressure roller and a pressure roller in contact with the pressure roller, the image carrier is driven by a driving force from a driving unit for rotationally driving the image carrier. And a pressure contact part separating means for separating at least one of the pressure contact parts by moving at least one of the pressure rolls,
Release means for releasing the separated state between the image carrier and the pressure roll by the pressure contact part separating means at a predetermined timing by utilizing the urging force of the urging means for bringing the image carrier and the pressure roll into pressure contact; The separating operation by the part separating means is performed when an image is not formed on the image carrier, and the releasing operation of the separated state by the releasing means is performed by the transfer medium entering between the pressure contact portion between the image carrier and the pressure roll. It is configured to include a control unit that is synchronized with the timing.

[0013]

In the image recording method according to the present invention, when an image is not formed on the image bearing member, at least one of the image bearing member and the pressure roll is driven by the driving force from the driving means for rotating the image bearing member. Is configured to move the pressure contact portion to separate the pressure contact portion. Therefore, even when the driving force for separating the pressure contact portion is obtained from the driving unit that rotationally drives the image carrier, the separation operation of the pressure contact portion is performed. Since it is performed when an image is not formed on the image carrier, the device can be downsized, and when the separating operation of the pressure contact portion is performed,
The formation of image defects is prevented without affecting the image formation on the image carrier. Further, in synchronization with the timing at which the transfer medium enters between the pressure contact portion of the image carrier and the pressure roll, the separation of the pressure contact portion of the image carrier and the pressure roll is configured to be released. Forming a pressure contact portion between the image carrier and the pressure roll in synchronism with the timing when the transfer medium enters between the pressure contact portions of the pressure rolls, and performing image transfer or simultaneous transfer and fixing on the transfer medium. Since the pressure contact pressure between the image carrier and the pressure roll does not fluctuate when the transfer medium enters between the pressure contact part between the image carrier and the pressure roll, the image defect caused by the fluctuation in the rotation of the image carrier is prevented. It is possible to reliably prevent the occurrence.

Further, in the image recording apparatus according to the present invention, when the image is not formed on the image carrier, the pressure contact portion separating means is used by the driving force from the driving means for rotationally driving the image carrier. Since the pressure contact portion is separated by moving at least one of the image bearing member and the pressure roll, the driving force for separating the pressure contact portion is obtained from the driving means for rotationally driving the image bearing member. Even in this case, the separating operation of the press contact portion is performed when an image is not formed on the image carrier, and therefore the device can be downsized, and the separating operation of the press contact portion is performed on the image carrier. The occurrence of image defects is prevented without affecting the image formation. Further, in synchronization with the timing at which the transfer medium enters between the pressure contact portion of the image carrier and the pressure roll, the releasing means releases the separation of the pressure contact portion of the image carrier and the pressure roll. The pressure contact portion is formed between the image carrier and the pressure roll in synchronization with the timing when the transfer medium enters between the pressure contact portion between the carrier and the pressure roll, and the image is transferred onto the transfer medium or the transfer is simultaneously fixed. The pressure contact pressure between the image carrier and the pressure roll does not fluctuate when the transfer medium enters between the pressure contact part between the image carrier and the pressure roll. It is possible to reliably prevent the occurrence of image defects.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an embodiment of an image recording apparatus for carrying out the image recording method according to the present invention.

In the figure, reference numeral 1 denotes a dielectric drum as an image carrier, which is rotationally driven in the direction of the arrow at a speed of 50 mm / s by a driving means (not shown). As the dielectric drum 1, for example, an aluminum drum whose surface is anodized and whose surface aluminum oxide is sealed with an epoxy resin is used. The surface hardness of the dielectric drum 1 is, for example, Vickers hardness of 500.

A recording head 2 as recording means is arranged near the surface of the dielectric drum 1.
An electrostatic latent image is formed on the surface of the dielectric drum 1 by the recording head 2 according to image information. As the recording head 2, for example, the one disclosed in JP-A-61-51355 is used.

The housing 20 of the recording head 2 includes:
As shown in FIG. 3, a conductive corona chamber 21, a corona wire 22 stretched in the conductive corona chamber 21 so as to extend in a direction perpendicular to the paper surface, and a corona wire 22 having a voltage of several thousand volts. A high voltage power supply 23 for applying a high voltage and a reference potential source 24 connected to the outer wall of the conductive corona chamber 21 are provided. Then, a high voltage is applied to the corona wire 22 from a high voltage power source 23 to generate a corona discharge, and the corona discharge generates ions of a constant polarity (preferably positive). The generated ions are attracted to the wall of the conductive corona chamber 21, and the inside of the conductive corona chamber 21 is filled with charged ions.

Further, a pressurized carrier fluid (preferably air) is fed into the conductive corona chamber 21 through an inlet channel 26 extending from the introduction pipe 25 in the arrow direction. This carrier fluid is for carrying a large number of ions filled in the conductive corona chamber 21 as an ion stream. This ion flow is discharged from the conductive corona chamber 21 to the outside of the conductive corona chamber 21 through the outlet channel 27 provided in the direction of the arrow, the ion modulation region 28, and the like.

The ion flow is controlled according to print information in the ion modulation region 28 when being discharged from the outlet channel 27 to the outside of the conductive corona chamber 21 by the carrier fluid. This is because when the ion flow passes through the ion modulation region 28, the thin film transistor (T
This is realized by selectively applying a low voltage source 31 of about 10 to 30 volts (DC) and a reference potential 32 using an FT) 30 according to print information.

That is, since the ion control electrode 29 and the opposing wall 28a which is grounded form a capacitor with a gap in the ion modulation region 28, the corresponding ion control electrode 29 is connected to the low voltage source 31 by the TFT 30. When connected, a low voltage is applied between the ion control electrode 29 and the opposing wall 28a, an electric field is selectively generated in the direction perpendicular to the flow direction of the carrier fluid, and the ion flow is bent. Then, this ion flow collides with the grounded opposing wall 28a to become neutral air molecules from the ionic state, and is released into the atmosphere. On the other hand, when the ion control electrode 29 is connected to the reference potential source 32 by the TFT 30, the ion beam between the ion control electrode 29 and the opposing wall 28a passes without being affected by the electric field.

The ion flow discharged through the outlet channel 27 to the outside of the housing 20 is pulled toward the dielectric drum 1, and the dielectric drum 1 receives the ion flow and is charged, and the surface thereof is charged. A latent image charge pattern is formed on the.

As the recording head 2, for example, those disclosed in JP-A-61-51355, JP-A-59-164154, and others are disclosed. Of course, you may use such as.

In this embodiment, the surface of the dielectric drum 1 is uniformly charged to −600 V by the scorotron 3 in order to accelerate and converge the ion flow from the recording head 2. As a result, as shown in FIG.
It is possible to record the electrostatic contrast as shown in (3) at a resolution of 300 SPI.

Further, in the vicinity of the surface of the dielectric drum 1, as shown in FIG. 2, a developing device 4 for visualizing the electrostatic latent image formed on the dielectric drum 1 is recorded. It is arranged on the downstream side of the head 2. As the developing device 4,
Known materials can be used and may be appropriately selected. In this embodiment, a conductive magnetic one-component developing system is adopted as the developing device 4, a developing bias is set to -600V, and a portion of -400V is developed. By this development, the surface potential of the developed portion is -600.
It becomes V.

The toner image formed on the dielectric drum 1 by the developing device 4 is simultaneously transferred and fixed on the transfer medium 6 by the pressure roll 5 which is pressed against the dielectric drum 1 by the pressure control means 13, and this transfer is performed. The medium 6 is discharged to the outside, and the image recording process is completed.

After that, the surface of the dielectric drum 1 is cleaned of residual toner and the like by a blade-shaped cleaner 12 to prepare for the next image recording step.

The transfer medium 6 is a transfer medium container 14
From the transfer medium delivery roll 9 to the pressure roll 5 in synchronization with the toner image formed on the dielectric drum 1 by the transfer medium delivery roll 10. Be done. At that time, the leading end of the transfer medium 6 is detected by the transfer medium detecting means 7. As the transfer medium detecting means 7, for example, a reflection type photo sensor is used.

Further, a transport roll 8 is arranged on the surface of the pressure roll 5. The transport roll 8 brings the transfer medium 6 into contact with the pressure roll 5, and transfers the transfer medium 6 onto the pressure roll 5. It is designed to be electrostatically attracted to. Further, the peeling claw 1 is provided on the surface of the pressure roll 5.
1 is in contact with the peeling claw 11. The peeling claw 11 is for peeling the transfer medium 6 after transfer and fixing from the pressure roll.

FIG. 5 shows the structure of the pressure roll.

This pressure roll 5 is, as shown in FIG.
Steel cored bar 51 and urethane resin 5 covering the cored bar 51
2 and. The hardness of the surface of the pressure roll 5 is set to 100 in Vickers hardness, for example.
The core metal 51 is grounded or a predetermined bias voltage is applied. When the core metal 51 is grounded, the resin layer 52 has a resistance value of about 10 ¹⁰ Ω,
When the core metal 51 is biased at -600V, 10 ⁸ Ω
The resistance value is as follows. In this embodiment, since the core metal 51 is grounded, the resistance value of the resin layer 52 is set to 10 ¹⁰ Ω.

As the pressure roll 5, a center support roll supported only at the central portion as disclosed in JP-A-49-77641 may be used. In this case, since the pressure uniformity may be compared with that of the solid roll, the skew angle may be 0 degree.

In this embodiment, by the driving force from the driving means for rotationally driving the image carrier, at least one of the image carrier and the pressure roll is moved to separate the pressure contact part from each other. Release means for releasing the separated state between the image carrier and the pressure roll by the pressure contact part separating means at a predetermined timing by utilizing the urging force of the urging means for bringing the image carrier and the pressure roll into pressure contact; The separating operation by the part separating means is performed when an image is not formed on the image carrier, and the releasing operation of the separated state by the releasing means is performed by the transfer medium entering between the pressure contact portion between the image carrier and the pressure roll. It is configured to include a control unit that is synchronized with the timing.

FIG. 1 shows a pressure control means 13 for bringing the pressure roll into pressure contact with the dielectric drum.

In the figure, reference numeral 5 denotes a pressure roll, and the pressure roll 5 is arranged so that the dielectric drum 1 and the central axis form a predetermined skew angle, for example, 0.4 degrees. There is. This pressure roll 5 has an arm 1
It is rotatably supported by 36. Also, this arm 1
Reference numeral 36 is swingable about a rotation shaft 139, and is biased upward by a spring 137 to press the pressure roll 5 against the dielectric drum 1 at a predetermined pressure, for example, a pressure of 20 Kg / cm ² . It is designed to be pressed with.

Further, at the tip of the arm 136,
A ratchet 140 is provided which engages with the arm 136 and prevents the arm 136 from being pressed into contact with the dielectric drum 1. The ratchet 140 is rotatably arranged around a rotation shaft 142, and a spring 146 for urging the ratchet 140 in a direction to release the engagement with the arm 136 is attached to the tip of the ratchet 140. Has been. A solenoid 141 for driving the ratchet 140 in a direction in which the ratchet 140 is engaged with the arm 136 against the tension of the spring 146 is connected to the tip of the ratchet 140.

In order to release the pressure contact state between the pressure roll and the dielectric drum 1, the arm 136 is moved to the vicinity of the tip of the arm 136 downwardly against the urging force of the spring 137. The cam 138 is provided. The cam 138 is normally in a state of being separated from the arm 136, and contacts the arm 136 only when the pressure roll 5 and the dielectric drum 1 are separated from each other and pushes down the arm 136 against the compression force of the spring 137. Is. Further, the cam 138 is connected to the electromagnetic clutch 14 from a driving means (not shown) of the dielectric drum 1 by a driving force transmitting means (not shown).
The driving force is transmitted through the motor 4 (FIG. 6) to rotate.

FIG. 6 is a block diagram showing the control circuit of the image recording apparatus according to this embodiment.

In the figure, reference numeral 131 designates a one-chip microprocessor which incorporates the program shown in the operation flow of FIGS. 7 and 8. The input port 133 of this one-chip microprocessor has a transfer medium detecting means. In addition to the detection signal from 7, the print request signal from the host computer to which the image recording apparatus is connected is input. A signal line to the electromagnetic clutch drive circuit 143 and the solenoid drive circuit 145 is connected to the output port 132 of the one-chip microprocessor 131, and a printer READY / N for notifying the host computer of the state of the image recording apparatus.
The OT READY signal is output.

With the above construction, in the image recording apparatus according to this embodiment, the occurrence of image defects due to the transfer medium rushing into the pressure contact portion is prevented as follows. That is, in this image recording apparatus, in the printer idle state before starting the image recording operation, in FIG. 1, the ratchet 140 is moved to the left in the drawing by the urging force of the spring 146 and is positioned away from the arm 136. The ratchet 140 and the arm 136 are disengaged. Therefore, the pressure roll 5 axially supported by the arm 136 is pressed against the dielectric drum 1 by the elastic force of the spring 137 at a skew angle of 0.4 degrees and a pressure of 20 Kg / cm ² .

As shown in FIG. 6, when the print request signal from the host computer is input to the 1-chip microprocessor 131 in the image recording apparatus (step 1 in FIG. 7), the dielectric drum 1 becomes As shown in FIG. 2, it is rotationally driven at a predetermined speed in the direction of the arrow by a driving means (not shown). 1-chip microprocessor 1
31 is an electromagnetic clutch control circuit 14 as shown in FIG.
3 to issue an operation command to put the electromagnetic clutch 144 into an operating state (step 2). Then, the driving force from the driving unit of the dielectric drum 1 is transmitted to the cam 138 via the electromagnetic clutch 144 by the driving force transmitting unit (not shown), and the driving force is stopped at the top dead center as shown in FIG. The cam 138 starts rotating. This cam 138 connects the arm 136 to the spring 1
The pressure roller 5 and the dielectric drum 1 are separated from each other by pushing down against the pressure contact force of 37. Then, the cam 138
When driven to the bottom dead center, the electromagnetic clutch 144
Is turned off to stop the rotation, and the pressure roll 5
The dielectric drum 1 is maintained in a separated state (steps 3 and 4).

Next, the one-chip microprocessor 1
31 outputs an operation command to the solenoid control circuit 145 to put the solenoid 141 into an operating state (step 5). Then, the ratchet 140 has the solenoid 141.
By this, the spring 146 is pushed forward against the pulling force of the spring 146, and the claw 140a is caught on the tip of the arm 136 as shown in FIG. After the pawl 140a of the ratchet 140 is caught on the tip of the arm 136, the electromagnetic clutch 14
4 is operated, the cam 138 is rotated to the top dead center, and the electromagnetic clutch 144 is turned off (step 6). When this happens, the 1-chip microprocessor 131
A PRINTER READY signal is sent to the host computer from the output port 132 (step 7).

PRINTER to host computer
During image recording after the READY signal is output, the transfer medium 6 is sent to the transfer nip portion 16 while being wound around the pressure roll 5 by the transfer medium sending roll 9 and the transfer medium transporting rolls 8 and 10. At that time, the leading end of the transfer medium 6 is detected by the transfer medium detecting means 7, and the detection signal is a 1-chip microprocessor 131.
Is notified (step 8).

The one-chip microprocessor 131 waits for a predetermined time after the detection signal of the transfer medium 6 is input from the transfer medium detection means 7 (step 9), and then issues an operation command to the solenoid control circuit 145. To release the operating state of the solenoid 141 (step 1
0). Here, the predetermined time is equal to the time required for the leading end of the transfer medium 6 to move to the transfer nip 16 after the transfer medium 6 is detected by the transfer medium detection unit 7. Therefore, when this predetermined time elapses, the leading end of the transfer medium 6 moves to just below the transfer nip 16 between the dielectric drum 1 and the pressure roll 5, which are in a separated state, as shown in FIG. In this embodiment, after the notification of the detection signal from the transfer medium detection means 7 for the predetermined time, 1
The time is set to 0 mm (distance from the position of the detection means 7 to the transfer nip 16) / 50 mm / s (process speed) = 0.2 seconds.

Then, when the operating state of the solenoid 141 is released, the ratchet 140 is pulled back by the restoring force of the spring 140, and as a result, the claw 140a is moved to the arm 1.
Leave 36. Therefore, the arm 136 has the claw 140.
The posture control by “a” is released, and the restoring force of the spring 137 pushes it upward, so that the pressure roll 5 is pressed against the dielectric drum 1 via the transfer medium 6. At this time, since the cam 138 is stopped at the top dead center, the arm 1
36 Does not hinder upward movement. Further, at this time, in order to control the speed at which the pressure roll 5 is pressed against the dielectric drum 1 due to the restoring force of the spring 137, as shown in FIG. 1, the dashpot 701 may be inserted in parallel with the spring 137. .

When the pressure roll 5 is brought into pressure contact with the dielectric drum 1 via the transfer medium 6, the tip of the transfer medium 6 is directly below the transfer nip 16 between the pressure roll 5 and the dielectric drum 1 or directly below it. Although it is located at a slightly advanced position, since a predetermined margin is set at the tip of the transfer medium 6, there is no hindrance to simultaneous transfer and fixing of images.

After the simultaneous transfer and fixing of the developed image onto the transfer medium 6 is completed (step 11), the one-chip microprocessor 131 sends the printer NOT R to the host computer.
An EADY signal is sent and the next print request signal is awaited (step 12).

In this way, before the image is formed on the dielectric drum 1, the pressure control means 13 is used to drive the pressure roll 5 by the driving force from the driving means for rotationally driving the dielectric drum 1. Since the transfer nip portion 16 is moved to separate the transfer nip portion 16, even if the driving force for separating the transfer nip portion 16 is obtained from the driving unit that rotationally drives the dielectric drum 1, the pressure contact portion is formed. The separation operation is performed when an image is not formed on the dielectric drum 1. Therefore, the apparatus can be downsized, and the image on the dielectric drum 1 can be obtained when the transfer nip portion 16 is separated. The formation of image defects is prevented without affecting the formation. Further, in synchronization with the timing of the transfer medium 6 entering between the transfer drum 6 and the transfer nip 16 of the pressure roll 5, the ratchet 140 releases the transfer drum 6 from the transfer nip 16 of the pressure roll 5. Therefore, the transfer nip portion between the dielectric drum 1 and the pressure roll 5 is synchronized with the timing when the transfer medium 6 enters between the transfer drum nip portion 16 of the dielectric drum 1 and the pressure roll 5. 16 can be formed to transfer an image onto the transfer medium 6 or simultaneously fix the transfer, and when the transfer medium 6 enters between the transfer nip portion 16 of the dielectric drum 1 and the pressure roll 5, Since the pressure contact pressure between the body drum 1 and the pressure roll 5 does not fluctuate, it is possible to reliably prevent the occurrence of an image defect due to the rotation fluctuation of the dielectric drum 1.

Second Embodiment FIGS. 9 and 10 show another embodiment of the present invention. The same parts as those of the above-mentioned embodiment are designated by the same reference numerals and will be described. The structures of the pressure contact portion separating means and the releasing means are different from those of the above embodiment.

FIG. 9 shows a pressure control means 13 for pressing the pressure roll against the dielectric drum.

In the figure, reference numeral 1001 denotes a shaft 1001 which receives power from a driving unit (not shown) of the image carrier 1 by a driving force transmitting unit (not shown). Also, the axis 100
At the end portion on the opposite side where the driving force transmission means of 1 is arranged,
The electromagnetic clutch 1002 is connected. Furthermore, axis 1
The electromagnetic clutch 1002 and the electromagnetic clutch 1004 are arranged at both ends of the shaft 006, and the mainspring 1003 is arranged substantially at the center of the shaft 1006. Axis 10
The electromagnetic clutch 1004 and the cam 138 are provided at both ends of 07.
, The cam 138 is normally in contact with the arm 136 at the top dead center, and the pressure roll 5 has a spring 137.
It is pressed against the dielectric drum 1 by the pressing force. The 1-chip microprocessor 131 contains the program shown in the flowcharts of FIGS. 11 and 12.
In such a configuration, the operation is as follows.

That is, in the printer idle state, as described above, the cam 138 normally contacts the arm 136 in the state of the top dead center, so that the pressure roll 5 has the spring 13
It is pressed against the dielectric drum 1 by the pressing force of 7. In this state, the print request signal from the host computer is 1
When input to the chip microprocessor 131, FIG.
As shown in 0, the electromagnetic clutch 1002 is turned on via the electromagnetic clutch control circuit 143, the shaft 1001 and the shaft 1006 are driven by the driving force transmission means (not shown), and the mainspring 1003 is wound. Turn on the electromagnetic clutch 1002 at the timing when the winding of the mainspring 1003 is completed.
FF. As a result, energy is stored in the mainspring 1003. Further, since the electromagnetic clutch 1004 has a ratchet mechanism incorporated therein, after the electromagnetic clutch 1002 is turned off, the shaft 1 is rotated by the mainspring 1003.
006 never starts to rotate.

In this state, the 1-chip microprocessor 131 prints to the host computer.
Send the R READY signal from the output port 132.
After that, the transfer medium 6 is sent to the transfer nip 16 by the transfer medium delivery roll 9 and the transfer medium transport rolls 8 and 10. The transfer medium detection unit 7 is a reflective photo sensor and detects that the transfer medium 6 has been conveyed. The detection signal from the transfer medium detection means 7 is
The one-chip microprocessor 131 is notified. In the 1-chip microprocessor 131, 8 mm after the notification (distance from the position of the detecting means 7 to the position immediately before the transfer nip 16) / 50 mm / s (process speed) = 0.16
After a while, the electromagnetic clutch control circuit 1004 is turned on and the ratchet is released. As a result, the shaft 1006 and the shaft 1007 start rotating due to the restoring force of the mainspring 1003, and at the same time, the cam 138 attached to the shaft 1007.
Also starts rotating from the top dead center and pushes the arm 136 downward against the pressure contact force of the spring 137. As a result, the pressure roll 5 and the dielectric drum 1 are separated from each other, and the transfer medium 6 projects into the gap. The cam 138 continues to rotate, and the mainspring 1
When 003 returns, the cam 138 returns to the top dead center. For such timing control, a deceleration means (not shown) is provided between the electromagnetic clutch 1004 and the cam 138. As the cam 138 returns to top dead center, the arm 138
The pressure roller 5 is pushed up by the pressure contact force of the spring 137, and is pressed against the image carrier 1 via the transfer medium 6.

After the transfer and fixing of the developed image onto the transfer medium 6 are completed, the printer NOT RE is transferred to the host computer.
A signal of ADY is sent, and the system waits for the next print request signal.

The other structure and operation are the same as those of the above-mentioned embodiment, and the description thereof will be omitted.

[0057]

According to the present invention, which has the above-described structure and operation, the unevenness of rotation of the image carrier when the transfer medium enters is suppressed by separating the image carrier and the pressure roll, and the image carrier driving means is provided. By separating the press contact portions by using the same drive source to reduce the size of the apparatus, and by performing the separation at the time of non-image formation, the rotation unevenness for the separation is also prevented and the image fluctuation caused by the rotation fluctuation is prevented. An image recording method and apparatus capable of preventing image defects such as distortion can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of essential parts showing an embodiment of an image recording apparatus according to the present invention.

FIG. 2 is a block diagram showing an embodiment of an image recording apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a recording head.

FIG. 4 is a schematic diagram showing the potential of an electrostatic latent image.

FIG. 5 is a sectional view showing a pressure roll.

FIG. 6 is a block diagram showing a control circuit.

FIG. 7 is a flowchart showing an operation.

FIG. 8 is a flowchart showing an operation.

FIG. 9 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 10 is a block diagram showing a control circuit in the embodiment.

FIG. 11 is a flowchart showing an operation.

FIG. 12 is a flowchart showing an operation.

[Explanation of symbols]

1 dielectric drum, 2 recording head, 5 pressure roll,
6 transfer medium, 7 transfer medium detecting means, 8 transport rolls, 136 arms, 140 chets, 141 solenoids.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keizo Abe, 2274 Hongo, Ebina, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Hiroaki Sato, 2274, Hongo, Ebina, Kanagawa Prefecture, Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. An electrostatic latent image is formed on the surface of an image carrier according to image information, and the electrostatic latent image is developed to develop the developed image.
In an image recording method of transferring or simultaneously fixing by transfer onto a transfer medium passing between pressure contact portions of an image carrier and a pressure roller that is in pressure contact, when the image is not formed on the image carrier, the image carrier By the driving force from the driving means for rotationally driving the body, at least one of the image carrier and the pressure roll is moved to separate the pressure contact portion, and thereafter,
Release the separation of the pressure contact portion by using the urging force of the urging means that presses the image carrier and the pressure roll in synchronism with the timing when the transfer medium enters between the pressure contact portion of the image carrier and the pressure roll. An image recording method characterized by. 2. An electrostatic latent image is formed on the surface of an image carrier according to image information, and the electrostatic latent image is developed to develop the developed image.
In an image recording apparatus that transfers by pressure onto a transfer medium that passes between the pressure contact portions of an image carrier and a pressure roller that is in pressure contact, or in an image recording apparatus that simultaneously fixes with transfer, by a driving force from a drive unit that rotationally drives the image carrier, The pressure contact portion separating means for separating at least one of the pressure contact portion by moving at least one of the image carrier and the pressure roll, and the separation state between the image carrier and the pressure roll by the pressure contact portion separating means, the image carrier and the pressure roll. The releasing means for releasing at a predetermined timing by utilizing the urging force of the urging means for pressing and the separating operation by the pressing contact separating means when the image is not formed on the image carrier, and the releasing operation is performed. And a control means for performing the releasing operation of the separated state by the means in synchronization with the timing at which the transfer medium enters between the pressure contact portion of the image carrier and the pressure roller. Image recording device.