JPH1091003A - Wet type image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet type image forming device where image soiling due to filming is prevented while performing image forming operation. SOLUTION: A reflection type sensor 41 performs filming detection on a photoreceptive drum 30 while moving in the direction of an arrow C. A detected value and a reference value previously set at a storing means 71 are compared by a CPU 40, so that the generation of the filming is judged. In the case that the generation of the filming is judged, the photoreceptive drum 30 is pressured by a blade 60 which is not also used as a device related to image forming until it reaches specified time. Then, the filming detection is performed again, and a series of the operation of the removal of the filming and the filming detection is repeatedly performed until the removal of the filming is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
A wet image forming apparatus for supplying a liquid developer by a developing device to a latent image carrier on which a latent image is formed to visualize the latent image, and then transferring the developed image to a transfer material by a transfer device. It is about.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, after a toner image is transferred to a transfer material, untransferred toner on a latent image carrier is removed by a cleaning means such as an elastic blade. If the removal is insufficient, the so-called filming phenomenon in which the residual toner adheres to the surface of the latent image carrier in the form of a film, which may cause image contamination.

[0003] As means for removing filming on the latent image carrier, for example, Japanese Patent Application Laid-Open No. 2-282770 discloses a peripheral speed of a transfer rotary member as a transfer device during transfer and during non-transfer. That is, filming on the latent image carrier is removed by changing the peripheral speed of the transfer rotator so that the transfer rotator rubs the latent image carrier during non-transfer. An image forming apparatus is disclosed.

[0004]

However, in the image forming apparatus, since filming is removed by a transfer rotating body as a transfer device, an image cannot be formed during the filming removing operation. There was a point.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a wet image forming apparatus capable of preventing an image stain caused by filming while performing an image forming operation. It is.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a liquid developer is supplied to a surface of a latent image carrier on which a latent image is formed by using a developing device to form the latent image. In a wet image forming apparatus for transferring the visualized image to a transfer material by a transfer device after the image is visualized, filming on the latent image carrier is removed. A means is provided.

In the wet image forming apparatus according to the first aspect, since filming on the latent image carrier is removed by filming removing means which does not double as an apparatus relating to image formation, image forming is performed even during the filming removing operation. It can be performed.

According to a second aspect of the present invention, in the wet image forming apparatus of the first aspect, a filming detecting means for detecting filming on the latent image carrier is provided, and the filming removal by the filming removing means is provided. The operation and the filming detection operation by the filming detection unit are alternately repeated until the value detected by the filming detection unit is compared with a preset setting value and it is determined that filming has been removed. It is characterized by performing.

In the wet image forming apparatus according to the second aspect, after the filming removing operation by the filming removing means, the filming detecting operation is performed by the filming detecting means, and the detected value detected by the detecting means is set in advance. Then, it is determined whether or not the filming has been removed by comparing the set value. This series of operations is repeated until it is determined that filming has been removed.

According to a third aspect of the present invention, in the wet image forming apparatus of the first aspect, filming detecting means for detecting filming on the latent image carrier is provided, and filming detection by the filming detecting means is provided. The operation is performed when the power is turned on and at a frequency of one transfer material or less.

In the wet image forming apparatus according to the third aspect, the filming detection operation by the filming detection means is performed when the power is turned on at the start of image formation, and in the unit of one transfer material or less during the image formation process. Perform at the frequency of

According to a fourth aspect of the present invention, in the wet image forming apparatus of the first aspect, a mechanism is provided as the filming removing means for pressing the latent image carrier or releasing the pressure. It is characterized by having.

In the wet image forming apparatus according to the present invention, the latent image carrier is pressurized by the filming removing means during the filming removing operation, and the latent image carrier is pressurized except during the filming removing operation. Is canceled. Therefore, the latent image carrier is not always pressed.

According to a fifth aspect of the present invention, in the wet image forming apparatus of the first aspect, display means for notifying a user that a filming removal operation is being performed is provided.

In the wet image forming apparatus according to the fifth aspect, the user is notified by the display means that the filming removal operation is being performed. Based on this display, the user can determine whether to form an image or not to form an image until filming is removed.

According to a sixth aspect of the present invention, in the wet image forming apparatus of the first aspect, filming detecting means for detecting filming on the latent image carrier is provided, and the latent image carrier is provided as the filming detecting means. A sensor is provided in a line shape perpendicular to the conveying direction of the image carrier.

In the wet image forming apparatus according to the sixth aspect, filming detection in a direction perpendicular to the conveying direction of the latent image carrier is performed line by line by a sensor provided in a line.

According to a seventh aspect of the present invention, in the wet image forming apparatus of the first aspect, a roller-shaped filming removing member is provided as the filming removing means.

In the wet-type image forming apparatus according to the present invention, the roller-shaped filming removing member moves the roller surface to change the contact position with the latent image carrier, and the filming on the latent image carrier is changed. Is removed.

According to an eighth aspect of the present invention, in the wet image forming apparatus of the seventh aspect, driving means for driving the filming removing member with respect to the latent image carrier at a different linear velocity ratio is provided. It is a feature.

In the wet image forming apparatus according to the present invention, the driving means drives the filming removing member at a different linear velocity ratio with respect to the latent image carrier, so that the removing member and the latent image carrier are separated. Filming on the latent image carrier is removed by generating a frictional force therebetween.

According to a ninth aspect of the present invention, in the wet image forming apparatus of the eighth aspect, the driving force of the filming removing member by the driving means is made variable.

In the image forming apparatus according to the ninth aspect,
By varying the driving force of the filming removing member, the linear velocity ratio of the filming removing member to the latent image carrier is changed, thereby changing the frictional force acting between the two members, that is, the filming removing force. Let it. The filming removal force increases as the linear velocity ratio increases, and decreases as the linear velocity ratio decreases. This change in linear speed ratio
For example, based on the value detected by the filming detection means,
It can be performed according to the degree of filming.

According to a tenth aspect of the present invention, in the wet image forming apparatus of the seventh aspect, the filming removing member is disposed so as to be driven by the latent image carrier, and the latent image carrier is driven by a driving source. The filming removing member driven as above is braked by a powder brake or an electromagnetic brake.

In the wet image forming apparatus according to the tenth aspect, the filming removing member and the latent image carrier are provided with a braking force by a powder brake or an electromagnetic brake to the filming removing member driven by the latent image carrier. A frictional force is generated during the process to remove filming on the latent image carrier.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] An embodiment (hereinafter, referred to as Embodiment 1) in which the present invention is applied to an electrophotographic copying machine (hereinafter, referred to as a copying machine) as an image forming apparatus will be described. FIG.
FIG. 2A is a front view illustrating a schematic configuration of the copying machine according to the first embodiment. This apparatus includes a transfer belt 1, a driving roller 2 as a transfer belt driving unit, a driven roller 3, and a transfer unit 4 including a driven roller 3. A yellow toner image forming unit Y, a magenta toner image forming unit M, a cyan toner image forming unit C, and a black toner image forming unit B for sequentially forming a toner image on the transfer paper 5 are provided.

Since the constructions of the toner image forming units Y, M, C, and B are common, the description will be made only for the yellow toner image forming unit Y, and the other toner image forming units will be described in the drawing. The portions corresponding to those in the portion Y are denoted by M, C, and B after the numbers assigned to those in the yellow toner image forming portion, and description thereof is omitted. In order to form a yellow toner image on the surface of the transfer paper 5 by an electrophotographic process, a writing device including a charging device and an exposure device is provided around the photosensitive drum 30Y as a latent image carrier of the yellow toner image forming portion Y. A unit 32Y, a developing device 33Y, a transfer device 34Y, a neutralizing device (not shown), and a cleaning device 36Y are arranged. Here, the visible image forming means for forming a visible image (toner image) on the photosensitive drum 30Y is a writing unit 32.
And a developing device 33Y. The developing device 34Y is a wet developing device that uses a two-component developer composed of a toner and a carrier or a one-component developer composed of a toner as a developer. The cleaning device 36Y includes a cleaning blade that removes residual toner on the photosensitive drum 30Y. Further residual toner on the photosensitive drum 30Y that cannot be removed by the cleaning device 36Y adheres to the surface of the drum 30Y as shown in FIG. 1B (hereinafter, this phenomenon is referred to as filming). Then, there is a possibility that a band-like image with a filming width is generated and image stains are generated. Therefore, in the first embodiment, a filming detecting unit that detects filming of the photosensitive drum 30Y and a filming removing unit that removes filming are provided between the cleaning device 36Y and the writing unit 32Y. . These means will be described later in detail.

The operation of the copying machine having the above configuration at the time of ordinary copying will be described. The transfer paper 5 supplied from the paper supply unit 8 is transferred to the transfer belt 1 via a registration roller 12.
Transported to the surface. The transfer belt 1 includes a transfer device 34
The transfer paper 5 is adsorbed on the surface by the charge given by Y. Here, the transfer belt 1 is rotated in the direction of arrow b by the rotational force transmitted from the drive roller 2, and the transfer paper 5
Is conveyed at the same speed as the peripheral speed of each of the photosensitive drums 30Y, 30M, 30C, and 30B provided in each of the toner image forming units Y, M, C, and B.

On the surface of the photosensitive drum 30Y rotating at the same speed as the transfer belt 1, each device arranged around the photosensitive drum 30Y forms a yellow toner image. That is, the charging device of the writing unit 32Y uniformly charges the surface of the photosensitive drum 30Y, and the exposure device
An electrostatic latent image is formed on the surface, and a developing device 33Y is formed on the electrostatic latent image.
Supplies the yellow toner and finally forms a yellow toner image. Then, the transfer device 34Y transfers the yellow toner image to the surface of the transfer paper 5 that has been conveyed by the transfer belt 1 to the nip portion NY formed by the transfer belt 1 and the photosensitive drum 30Y. That is, the transfer device 34Y applies an electric charge to the transfer belt 1 to generate an electric field near the nip portion NY, and electrostatically moves the charged yellow toner image on the surface of the photosensitive drum 30Y in the direction of the transfer paper 5. Let me
The yellow toner image is transferred to the transfer paper 5. Then, the residual charge on the surface of the photoreceptor drum 30Y is removed by a charge removing device (not shown), and the yellow toner remaining on the surface of the drum 30Y is removed by a cleaning device 36Y.

The transfer belt 1 having the yellow toner image adhered to the surface by the above operation is transferred to the transfer belt 1.
And a nip portion N formed by the magenta toner image forming portion M
M, nip portion N formed by cyan toner image forming portion C
C and the toner is sequentially conveyed to a nip portion NB formed by the black toner image forming portion B. The magenta toner image forming section M forms a magenta toner image in the nip section NM, the cyan toner image forming section forms a cyan toner image in the nip section NC, and the black toner image forming section B forms a black toner image in the nip section NB. Are sequentially transferred to the transfer paper 5, and each toner image is superimposed on the surface of the transfer paper 5.

Then, the separation device 7 removes a part of the charge electrostatically adsorbing the transfer paper 5 distributed on the transfer belt 1, whereby the transfer belt 1 and the transfer paper 5 are electrostatically separated. The transfer paper 5 on which the toner images of four colors are superposed is separated from the surface of the transfer belt 1 due to its rigidity due to the weakened suction force. Then, the transfer paper 5 is conveyed to a fixing device 9, and after the fixing device 9 fixes the toner image on the transfer paper 5, the transfer paper 5 is discharged to a paper discharge unit 10 via a paper discharge roller 13. You. When the above-described copying operation is completed, the residual charge is removed by the charge removing device 11 to remove the toner attached to the surface of the transfer belt 1.

Next, the filming detecting means and the filming removing means according to the first embodiment will be described with reference to FIG. Since each of the toner image forming units Y, M, C, and B has the same mechanism, the description will be made only for the yellow toner image forming unit Y.

The filming detecting means has a reflection type sensor 41 comprising an LED 41a as a light emitting element and a phototransistor 41b as a light receiving element. The reflective sensor 41 includes a first pulley 42a driven by a motor 39 and a second pulley 4 driven by the first pulley 42a.
2b can be moved in the direction of arrow C in parallel with the photosensitive drum axis via the wire 43.

The filming removing means includes a blade 60 as a filming removing member, a hinge unit 61 for supporting the blade 61 by a hinge supporting member 61a, one end of which is fixed to the copying machine main body, and the other end of which is fixed to the main body of the copying machine. A spring 63 supporting the hinge unit 61;
The solenoid 62 turns ON / OFF the pressure of the blade 60 with respect to the photosensitive drum 1 based on the signal from 40. The blade 60 is a member made of a fine-grained compound, a nonwoven fabric, or a resin sprayed with powder used for cleaning a video head. Further, a member having a web shape may be used instead of the blade.

Here, a series of operations for filming detection and filming removal will be described. When the photosensitive drum rotates after the power of the copier is turned on, the reflection type sensor 41
Is in a detectable state by the LED ON signal from the CPU 40, and performs a filming detection operation while moving in the direction of arrow C with the rotation of the motor 39. That is,
The phototransistor 41b detects the amount of light emitted from the LED 41a and reflected on the surface of the photosensitive drum 30Y. This detected value is input to the CPU 40 via the amplifier (AMP) 44 as a voltage value. The CPU 40
Reference is made to a reference value preset in the storage means 71 such as M or RAM, and the reference value is compared with a detected value to determine whether or not filming has occurred on the photosensitive drum 30Y.

When filming on the photosensitive drum 1 is detected by the filming detecting means, the blade 60 presses the photosensitive drum 1 according to a solenoid ON signal from the CPU 40. This pressurization is released by a solenoid OFF signal from the CPU 40 when a specified time set in advance by the timer 70 is reached. After the completion of the filming removal operation, the filming detection means performs a filming detection operation on the photosensitive drum 1. As a result, if it is determined that the filming has not been removed, the filming removing means performs the filming removing operation again. The above-described series of operations of filming removal and filming detection are repeated until a comparison between the reference value and the detected value determines that filming on the photosensitive drum 1 has been completely removed.

The filming detecting operation by the filming detecting means is performed when power is turned on at the start of image formation.
In addition, the image forming process is performed at a frequency of one transfer sheet or less. Also, during the filming removal operation,
The display means 47 informs the user that the removal operation is being performed. Based on this display, the user can determine whether to form an image or not to form an image until filming is removed.

Further, a light source and a CCD may be used instead of the reflection type sensor 41. Further, when the photosensitive drum is rotated, a latent image is formed by applying a developing bias or by uniformly performing optical writing (LD) on the drum 1 to reduce the surface potential of the photosensitive drum 1 at that time. It may be detected by a potential sensor.

As described above, in the first embodiment, the filming removing operation and the filming detecting operation are repeated until the filming detecting means determines that the filming on the photosensitive drum 1 has been removed. Accordingly, filming on the photosensitive drum 1 can be reliably removed regardless of the manner of attachment of the toner to the photosensitive drum 1 and the type of the attached toner.

Further, in the first embodiment, since the image forming operation can be performed even during the filming removing operation by providing the dedicated filming removing member, downtime of the copying machine can be reduced.

In the first embodiment, since the filming detection is performed frequently at the time of turning on the power and during the image forming process, the filming detection rate can be increased and the occurrence rate of the abnormal image can be reduced.

In the first embodiment, the blade 60 as the filming removing member contacts the photosensitive drum 1 during the filming removing operation and does not contact except during the filming removing operation. Damage to the drum 1 due to damage or wear can be reduced.

[Second Embodiment] Next, a copying machine according to another embodiment of the present invention (hereinafter, referred to as a second embodiment) will be described. The copying machine according to the second embodiment basically has the same configuration as that of the first embodiment. The difference is that the first embodiment is a reflection type sensor 4
Embodiment 2 is different from Embodiment 1 in that a CCD sensor arranged in a line is provided, whereas Embodiment 1 is provided with a blade 60 as the filming removing member. The second embodiment is characterized in that a removing roller is provided to make the filming removing force variable. Hereinafter, these points will be described.

FIG. 3 is an explanatory view of the configuration of the filming detecting means and the filming removing means according to the second embodiment. The filming detecting means includes a color C arranged in a line perpendicular to the rotation direction of the photosensitive drum 1.
A CD sensor 74 is provided. When the photosensitive drum rotates after the power of the copier is turned on, the color CCD sensor 74
Detectable by ON signal from CPU 40,
A filming detection operation is performed for each line in the image forming area of the photosensitive drum 1. That is, reflected light from a light source (not shown) is detected as a voltage value by the color CCD sensor 74. This detection value is input to the input level conversion circuit 72.
Is compared with a preset reference value, that is, a voltage level which affects an image by filming, and is binarized to H, for example, without filming, and to L, with filming. The binarized data is taken into the data conversion circuit 73, and it is determined whether or not filming has occurred. When the occurrence of filming is determined, a filming confirmation signal is transmitted from the data conversion circuit 73 to the CPU 40, and the filming removing operation by the filming removing means is started. Further, the CPU 40 informs the user through the display means 47 that the filming removal operation is being performed.

As described above, the second embodiment is different from the color CCDs arranged in a line as filming detecting means.
By providing the sensor 74, filming detection in the direction perpendicular to the rotation direction of the photosensitive drum 1 can be performed at once in a line unit, so that the speed of filming detection can be increased.

The filming removing means has a removing roller 75 and a removing roller driving means comprising a stepping motor 77 and a driver circuit 76.
By this removing roller driving means, the removing roller 75 rotates in a direction opposite to the direction of rotation of the photosensitive drum 1 at a linear speed different from the rotation. As a result, a frictional force is generated between the removing roller 75 and the photosensitive drum 1, and the filming on the photosensitive drum 1 is removed by the frictional force.

The ratio of the linear velocity of the removing roller 75 to the photosensitive drum 1 is variable. Therefore, for example, based on the value detected by the filming detection unit,
The frictional force, that is, the filming removal force can be changed according to the degree of filming.

As described above, in the second embodiment, since the contact position with the photosensitive drum 1 is changed by providing the filming removing member with the roller shape, the filming removing member is different from the first embodiment. Life can be extended.

In the second embodiment, since the filming removing force can be changed according to the degree of filming by the removing roller driving means, the filming removing force is reduced when the degree of filming is small. As a result, the damage and deterioration of the latent image carrier can be reduced, and when the degree of filming is large, the filming removal force can be increased to efficiently perform filming removal.

Instead of the removing roller driving means including the stepping motor 77 and the driver circuit 76, a removing roller 75 is provided so as to be driven by the photosensitive drum 1, and the drum 1 is driven as a driving source. A frictional force may be generated between the removal roller 75 and the photosensitive drum 1 by braking the removal roller 75 with a powder brake or an electromagnetic brake. According to this configuration, filming can be removed by a device that is less expensive than the above-described removal roller driving unit. The braking force of the brake can be varied by changing the voltage value using a voltage variable circuit.

[0051]

According to the first aspect of the present invention, an image can be formed during the filming removing operation, and the latent image carrier is reliably fed back to the filming removing means by the filming detecting means. The upper filming can be removed. Therefore, there is an excellent effect that image contamination due to filming can be prevented while performing an image forming operation.

According to the second aspect of the present invention, a series of operations of filming removal and filming detection are repeatedly performed until it is determined that filming has been removed.
There is an excellent effect that filming can be reliably removed regardless of the manner of attachment of the toner to the latent image carrier and the type of the attached toner.

According to the third aspect of the present invention, the filming detection operation is performed frequently at the start of image formation and during the image formation process, thereby increasing the filming detection rate and reducing the occurrence rate of abnormal images. There is an excellent effect that it can be reduced.

According to the fourth aspect of the present invention, since the latent image carrier is not constantly pressed, there is an excellent effect that damage and deterioration of the latent image carrier can be reduced.

According to the fifth aspect of the present invention, it is possible to form an image at the discretion of the user by providing the display means or to interrupt the image formation until the filming is removed. There is an excellent effect that the user can judge whether or not to perform image formation accordingly.

According to the invention of claim 6, since the filming detection in the direction perpendicular to the conveying direction of the latent image carrier can be performed at once in line units, the speed of the filming detection can be increased. There is an excellent effect that it can be done.

According to the seventh aspect of the present invention, since the contact position between the filming removing member and the latent image carrier changes, an excellent effect of extending the life of the filming removing member can be achieved. is there.

According to the eighth aspect of the present invention, the filming removing means can be constituted by a simple mechanism for generating a frictional force between the filming removing member and the latent image carrier due to a difference in linear velocity. Has an effect.

According to the ninth aspect of the present invention, since the filming removing force can be changed according to the filming degree, the filming removing force is reduced when the filming degree is small. It is possible to reduce the damage and deterioration of the latent image carrier, and when the degree of filming is large, there is an excellent effect that the filming removal force can be increased and filming removal can be performed efficiently.

According to the tenth aspect of the present invention, the filming removing means is constituted by an inexpensive device in which the filming removing member driven by the latent image carrier as a driving source is braked by a powder brake or an electromagnetic brake. There is an excellent effect that it can be done.

[Brief description of the drawings]

FIG. 1A is a front view showing a schematic configuration of a copying machine according to the present invention. (B) is an explanatory view of filming of the photosensitive drum.

FIG. 2 is a configuration explanatory diagram of a filming detection unit and a filming removal unit according to the first embodiment.

FIG. 3 is a configuration explanatory diagram of a filming detection unit and a filming removal unit according to a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transfer belt 2 drive roller 3 driven roller 4 transport unit 5 transfer paper 7 separation device 8 paper feed unit 9 fixing device 10 paper discharge unit 11 static elimination device 12 registration roller 13 paper discharge roller 30 photosensitive drum 32 writing unit 33 developing device 34 Transfer device 36 Cleaning device 40 CPU 41 Reflection type sensor 42a, 42b First and second pulleys 43 Wire 44 Amplifier 46 System controller 47 Display device 60 Blade 61 Hinge unit 62 Solenoid 63 Spring 70 Timer 71 ROM 72 Input level conversion circuit 73 Data Conversion circuit 74 Color CCD sensor 75 Removal roller 76 Driver circuit 77 Stepping motor Y Yellow toner image forming section M Magenta toner image forming section C Cyan toner image forming section B Rack toner image forming unit

Claims (10)

[Claims] A latent image is formed on a surface of a latent image carrier on which a latent image is formed by supplying a liquid developer with a developing device to visualize the latent image. Then, the latent image is transferred to a transfer material by a transfer device. A wet image forming apparatus, comprising: a filming removing unit that removes filming on the latent image carrier and that does not double as a device related to image formation. 2. A wet image forming apparatus according to claim 1, further comprising filming detecting means for detecting filming on said latent image carrier, filming removing operation by said filming removing means, and filming detection. And a filming detecting operation by the means is repeated alternately until the filming is removed by comparing the detection value of the filming detecting means with a preset value. Image forming device. 3. The wet image forming apparatus according to claim 1, further comprising filming detection means for detecting filming on the latent image carrier, wherein the filming detection operation by the filming detection means is performed when power is turned on. And a wet image forming apparatus, wherein the frequency of the transfer is performed at a frequency of one transfer material or less. 4. A wet-type image forming apparatus according to claim 1, wherein a mechanism is provided as said filming removing means for pressing said latent image carrier or releasing said pressure. Image forming device. 5. The wet image forming apparatus according to claim 1, further comprising a display unit for notifying a user that a filming removing operation is being performed. 6. A wet image forming apparatus according to claim 1, further comprising filming detecting means for detecting filming on said latent image carrier, wherein said filming detecting means is provided in a conveying direction of said latent image carrier. A wet image forming apparatus, wherein sensors are arranged in a line in a direction perpendicular to the image forming apparatus. 7. The wet image forming apparatus according to claim 1, wherein a roller-like filming removing member is provided as said filming removing means. 8. A wet image forming apparatus according to claim 7, further comprising driving means for driving said filming removing member at a different linear velocity ratio with respect to said latent image carrier. . 9. The wet image forming apparatus according to claim 8, wherein a driving force of said filming removing member by said driving means is made variable. 10. The wet image forming apparatus according to claim 7, wherein the filming removing member is arranged to be driven by the latent image carrier, and the filming removing member is driven by using the latent image carrier as a driving source. A wet image forming apparatus, wherein a member is braked by a powder brake or an electromagnetic brake.