JP2598131C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention forms an electrostatic latent image on an image carrier such as a photoreceptor and develops the electrostatic latent image to form a paper And the like. (Prior Art) As this type of recording apparatus, an electrophotographic apparatus, an electrostatic printer, and the like are known. In these recording apparatuses, after forming an electrostatic latent image on a photoreceptor, a developer is electrostatically attached to the electrostatic latent image to form a developer image, and subsequently, the developer image is formed on paper. It is recorded by transcription. Further, since the electrostatic latent image and the developer that cannot be transferred remain on the photoreceptor after the transfer, the residual developer is removed by a cleaning device, and then the electrostatic latent image is removed by a charge removing device. doing. In recent years, there has been a demand for miniaturization of the apparatus.
Japanese Patent Publication No. 538 discloses a method of reducing the size of an apparatus by using a single apparatus as both a developing device and a cleaning device. In this method, in one developing device, the electrostatic latent image is developed when the photosensitive drum passes here for the first time, and subsequently, the photosensitive drum is passed through the developing device for the second time to clean the residual image after transfer. I have. However, in this conventional method, the residual image is removed from the photosensitive drum when the photosensitive drum approaches the second pass to the developing device, so that the recording speed is reduced by half and the peripheral speed of the photosensitive drum is reduced. There is a problem that a recording area larger than the size of the entire surface cannot be obtained, so that the photosensitive drum must necessarily have a relatively large size, and the apparatus cannot be sufficiently reduced in size. On the other hand, U.S. Pat. No. 364,926 discloses a developing device for simultaneously developing an electrostatic latent image and cleaning a developer remaining after the previous transfer at the time of the first passage of the electrostatic latent image. A method is disclosed that solves the drawbacks related to speed by using. (Problems to be Solved by the Invention) However, in this conventional apparatus, while the residual image after transfer remains on the photosensitive drum, the next charging, formation of an electrostatic latent image, and development are performed from above. Becomes Therefore, in charging, the remaining latent image and the toner image are superimposed and charged, and further uniform image formation and latent image formation are impaired in order to perform the next image exposure from above the toner image, Since the afterimage of the previous process appears as a so-called memory image overlapping with the next image, there is a disadvantage that the image becomes unclear. Such development is particularly likely to occur when a solid portion (a region where the developer is adhered over a wide area) and a thin line such as a character formed in the previous process are encountered. Since the developer image cannot be sufficiently removed, the developer image may remain as an afterimage memory and may be directly transferred to a sheet. Further, in order to reduce the size of the recording apparatus, a one-component system is preferable as a developing device, but a method using a one-component system having poor mechanical cleaning power has not been realized. The present invention has been made in view of such circumstances, and has as its object to provide a smaller image forming apparatus capable of obtaining a clear image. [Constitution of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention is directed to a latent image forming an electrostatic latent image of a predetermined polarity on an image carrier. Forming means, and an elastic developing roller carrying a non-magnetic one-component developer frictionally charged to the same polarity as the predetermined polarity so as to be used for development, and pressing the elastic developing roller against the image carrier. Forming a contact area of a predetermined length with the image carrier by elastic deformation, and rotating and contacting the image carrier with a peripheral speed difference, thereby forming the latent image. Means for supplying the developer on the elastic developing roller to the electrostatic latent image formed by the means to perform reversal development,
The image forming apparatus further includes a developing and cleaning unit that removes a residual developer on the image carrier, and a transfer unit that transfers a developer image formed on the image carrier by the developing and cleaning unit onto a material to be transferred. A latent image forming means for forming an electrostatic latent image of a predetermined polarity on a rotating image carrier, and a non-charged non-charged toner having the same polarity as the predetermined polarity for use in development. An elastic developing roller for carrying a magnetic one-component developer is provided, and the elastic developing roller is brought into sliding contact with the image carrier while being pressed against the image carrier, thereby forming an electrostatic latent image formed by the latent image forming means. Developing cleaning means for supplying the developer on the elastic developing roller to perform reversal development and simultaneously removing the residual developer on the image carrier; and slidingly contacting the elastic developing roller with the image carrier. Rotating means for rotating the elastic developing roller while having a peripheral speed difference with the peripheral speed of the image carrier, and pressing the elastic developing roller against the image carrier. And a linear load on the elastic developing roller. A load unit for applying a load of 20 g / cm to 120 g / cm, a transfer unit for transferring a developer image formed on the image carrier by the developing and cleaning unit onto a material to be transferred, and a transfer unit. And an image disturbing means for disturbing the developer remaining on the image carrier to form a non-pattern after transferring the developer image. According to a third aspect of the present invention, there is provided a latent image forming means for forming an electrostatic latent image of a predetermined polarity on a rotating image carrier, and a non-charged non-charged toner having the same polarity as the predetermined polarity used for development. An elastic developing roller for carrying a magnetic one-component developer is provided, and the elastic developing roller is brought into sliding contact with the image carrier while being pressed against the image carrier, thereby forming an electrostatic latent image formed by the latent image forming means. A developing cleaning unit for supplying the developer on the elastic developing roller to perform reversal development and removing a residual developer on the image carrier, and slidably contact the elastic developing roller with the image carrier. Rotating means for rotating the elastic developing roller at a peripheral speed of 1.5 to 4 times the peripheral speed of the image carrier, and pressing the elastic developing roller against the image carrier. , And a line weight is applied to the elastic developing roller. And weighting means for applying a load of 20 g / cm to 120 g / cm, the developer image formed on the image bearing member; and a transfer means for transferring onto a transfer material by the developing cleaning means. (Function) An elastic developing roller carrying a non-magnetic one-component developer charged by friction is pressed against the image carrier to form a nip width, and is rotated with a peripheral speed difference between the roller and the image carrier. This makes it possible to enhance the efficiency of recovering the residual developer by improving the mechanical peeling and cleaning ability of the residual developer at the same time while performing the development satisfactorily. Further, after the transfer of the developer image by the transfer means, the developer remaining on the image carrier is disturbed by the image disturbing means to be non-patterned, so that the residual developer on the image carrier is uniformly dispersed. When the elastic developing roller is pressed, uniform disturbing sliding contact with the developer on the elastic developing roller is more likely to occur. Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 shows a recording apparatus in which a photosensitive drum 1 as an image carrier having a recording surface smaller than the area of an image to be recorded (that is, having a small diameter) is provided at an approximate center of a main body H thereof. It is provided rotatable in the A direction. The photoconductor drum 1 is formed of an organic photoconductor (OPC) -based photoconductive material. Around the photosensitive drum 1, along the rotation direction thereof, a charging charger 2, a laser device 3, a developing / cleaning device 4 as a developing / cleaning device, a transferring device 5 as a transferring device, a charge removing lamp 6, and an image A disturbing device 7 as disturbing means is provided. The charging charger 2 is located above the photosensitive drum 1, and is configured to uniformly and negatively charge the surface of the photosensitive drum 11 to -500 to -800 volts. The laser device 4 irradiates a laser beam 8 on the surface of the photoconductor in accordance with image information to be recorded, and forms an electrostatic latent image on a charged area. Further, the developing cleaning device 4 is provided with a hopper 9 for storing a so-called one-component developer T having triboelectric charging property. In the hopper 9, the developer T is charged with the photosensitive drum 1.
An elastic developing roller (hereinafter referred to as a developing roller) 10 that transports the developer T remaining on the photosensitive drum 1 to the inside of the hopper 9 is provided. The developing roller 10 is provided with a conductive surface layer 11 having an electric resistance of 10 ² to 10 ⁹ Ωcm, and an elastic layer 12 made of foamed urethane is disposed inside the conductive surface layer 11 to form an elastic roller as a whole. . An elastic blade 13 made of phosphor bronze, urethane, or silicone resin for forming a thin layer is pressed against the developing roller 10 while frictionally charging the developer T, and the developer T passing therethrough is One or two developer layers are formed with negative charge of the same polarity as the photosensitive drum 11. still,
The surface of the developing roller 10 needs to be selected in consideration of frictional charging with the developer T and appropriate elasticity and friction. The material of the surface layer 11 is formed by applying, for example, a mixture of urethane resin and conductive carbon in an amount of 10 to 30% by weight. Further, a bias power source 14 is connected to the developing roller 10 and is electrically connected to the surface layer 11. As a result, a predetermined developing bias is applied during development and cleaning. A sponge-like developer transport roller 15 is further provided in the hopper 9, and serves to prevent aggregation of the developer T in the hopper 9 and to transport the developer. The elastic transfer roller 5 is provided substantially below the photosensitive drum 1 and facing the peripheral surface of the photosensitive drum 1 via a paper conveyance path 16. The transfer roller 5 has the same structure as the developing roller 10, but the electric resistance of the surface layer 11 is 10 ⁵ Ωcm to 10 ¹⁰ Ωcm. The transfer roller 5 applies a voltage of 800 to 1800 volts to the back surface of the paper 17 conveyed thereto, electrostatically attracts the toner, and transfers the toner image from the photosensitive drum 1 to the paper 17. . Such a contact-type transfer unit exhibits stable transfer characteristics even under humid conditions, which has the effect of reducing the amount of transfer residual developer and reducing the burden of cleaning, and also reduces paper dust in the transfer paper. Removed to prevent mixing into the developer. The disturber 7 is provided with a conductive elastic brush 18, and the tip of the conductive brush 18 is brought into contact with the photosensitive drum 1. The elastic brush 18 is slid in contact with the rotation of the photosensitive drum 1, and a voltage of 0 to 400 volts is applied thereto. The elastic brush 18 disturbs the transfer residual developer on the photosensitive drum 1 to be in an unreadable state, that is, a non-patterned state. At the same time, the residual electrostatic latent image is also erased and erased by the conductive brush 18. Prior to this, since the charge on the negative side of the photosensitive drum 1 has been erased by the erase lamp 6, the charge removal by the brush 18 has the effect of mainly eliminating the charge on the positive side. Further, since the disposition device 7 is located above the photosensitive drum 1, even if the developer is accumulated on the brush 18, the developer falls onto the drum 1 and is conveyed on the drum 1 as it is and the developing device 4 The advantage is that it does not fall or scatter in the machine. A paper supply unit 19 that supplies the paper P to the transport path 16 is provided below the photosensitive drum 1. The paper supply unit 19 stores paper 17 on which an image is to be transferred. Above the paper supply unit 19, a paper supply roller 20 for supplying the paper P from the paper supply unit 19 to the transport path 16 by rotation is provided. The transport path 16 is provided with a fixing device 21 for fixing the toner image transferred onto the paper 17. Next, the operation of the electronic copying apparatus according to this embodiment will be described. The photosensitive drum 1 is rotated in the direction of arrow A, and the peripheral surface of the photosensitive drum 1 is corona-charged by the charging charger 2 to about minus 500 to 800 V (volt). Subsequently, the charged area is irradiated with a laser beam 8 from the laser device 3 and exposed to form an electrostatic latent image on the surface of the photosensitive drum 1. The electrostatic latent image is then transferred to the developing cleaning device 4.
Is transported to the developing cleaning position facing the surface. A developer (hereinafter, referred to as toner) T is sent out from the developing roller 10 of the developing and cleaning device 4, and is brought into contact with the electrostatic latent image elastically and with a nip width due to deformation to cause the toner T to adhere to the electrostatic latent image. Form an image. In this case, the toner T adheres to the light irradiation area and is subjected to so-called reversal development. The toner T is charged to about minus 5 to 30 μc / g (micro coulomb / gram) by friction between the blade 23 and the surface layer 11 of the developing roller 10, and a voltage of about minus 200 to 450 volts is applied to the developing roller 10. Force is applied. The developed toner image is then conveyed to a transfer area facing the transfer roller 5.
On the other hand, the paper 1 is transferred from the paper feeding unit 19 to the transfer area by the rotation of the paper feeding roller 20.
7 is sent in synchronization with the rotation of the photosensitive drum 1. The back surface of the paper 17 is charged to a positive polarity by the transfer roller 5. Therefore, the toner image on the surface of the photosensitive drum 1 is electrostatically attracted to the paper P and transferred. Here, the transfer roller 5 is supplied with a DC power
A voltage of 0 volts to 2000 volts is applied to the rotating shaft, and 10 ^{5 on} the roller surface is passed through a conductive portion formed by mixing 30 to 40% by weight of conductive carbon with silicon resin provided at both ends of the transfer roller ^5. A voltage is applied to the conductive surface portion of 〜１０10 ⁹ Ωcm. The surface of the transfer roller 5 is preferably made of a material having a smooth surface and low friction in order to make it easier to clean foreign substances such as developer and paper dust. Since the cleaning blade 22 is used, the cleaning blade 22 is preferably used. Further, the transfer roller 15 having a flexible rubber height of 25 to 50 degrees as measured by the JIS method had a wide tolerance of the pressing force of the transfer roller 5 against the photosensitive drum 1 and was good. The favorable transfer characteristic range (operating environment) by the transfer roller 5 is shown by oblique lines in FIG. Similarly, the measurement by the conventional transfer corona is shown in FIG. According to this comparison, according to the transfer roller 5, the transfer efficiency is 85% in the range of the relative humidity of 30% to 85%.
In contrast to the above, it can be seen that in the corona transfer method, transferability is maintained only up to 70% even when the transfer efficiency is allowed up to 30% and 60%. This means that in a recording apparatus having no cleaning apparatus as in the present invention, the transfer residual toner rapidly increases under humid conditions, and the maximum cleaning failure of a so-called cleanerless recording apparatus without a conventional cleaning apparatus. It was the cause. As described above, the contact-type transfer by the elastic conductive transfer roller 5 reduces the transfer residual toner with extremely high efficiency and over a wide range of environments, and directly contacts the sheet 17 during transfer. Since the paper dust adhering to the photosensitive drum 1 is also efficiently absorbed and removed, the amount of adhering matter remaining on the photosensitive drum 1 after transfer is extremely reduced. Furthermore,
By using the transfer roller 5, the paper 17 is mechanically pressed, so that transfer omission (partially not transferred) is prevented, and the size and quality of the paper 17 are less affected and a clear image is formed. Is transferred. The paper 17 after the transfer is sent to the fixing device 21, where the toner is melted and fixed on the paper 17 and then discharged. By the way, the toner image remaining slightly untransferred on the surface of the photosensitive drum 1 after the transfer or the positive and negative electrostatic latent operations left after the toner transfer remain. For these toner images or electrostatic latent images, first, a negative latent image is erased by the erase lamp 6, and the residual toner is slight.
Next, it is conveyed to the disturber 7 to be disturbed and non-patterned. In the disturber 7, the elastic brush 18 is brought into contact with the electrostatic latent image to exert a mechanical and electrostatic force so that the residual toner image and the electrostatic latent image are disturbed finely to an unreadable state. In this case, the frictional charging property of the brush material is set to the same polarity as that of the toner to generate a repulsive force with the toner, so that the remaining toner is not adsorbed from the surface of the photosensitive drum 1. That is, the toner is not accumulated in the brush 18. When a conductive material is used as the brush material, a repulsive force is generated by applying a potential having the same polarity as the toner or a ground potential to prevent the toner from accumulating on the brush. In this way, the afterimage is disturbed, and most of the toner is scattered on the surface of the photosensitive drum 1 and adheres thereto, but hardly accumulates in the charge disturber 7. That is, the charging disrupter 7 does not have a function as a cleaning device, but has an auxiliary function. The toner T scattered on the surface of the photoreceptor drum 1 is distributed in a sufficiently small dot shape and no longer has information as characters or images. The disturbed area is then conveyed to a charging position facing charging charger-2, and overlaid thereon to be corona charged. After the charging, the latent image is exposed by the laser device 3 to form an electrostatic latent image, and then reaches the developing cleaning position (second time) facing the developing cleaning device 4 again. In this case, in the electrostatic latent image formed for the second time, the transfer residual toner is significantly reduced by the roller transfer also in the exposed portion (image portion to which toner is to be attached) and the non-exposed portion (non-image portion). In addition, since the residual toner is scattered almost uniformly and sufficiently thin in advance, uneven exposure does not occur. Therefore, even in the second development, a uniform toner image is obtained because the residual potential after exposure becomes uniform. Here, as described above, the developing roller 10 is to have a 10 ² to 10 ⁹ [Omega] cm conductivity with an elastic 30-70 degrees JIS rubber hardness measurement method, the developing roller 1
0 to the photosensitive drum 1 as a line weight.
At a contact point in the same direction and at a peripheral speed of 1.5 to 4 times with a pressure difference, a contact width (nip) of 1 to 4 mm is generated. Since the toner T on the developing roller 10 comes into sliding contact with the toner, a strong frictional force is generated, and the cleaning ability is enhanced. However, since the developer is formed only by the toner T, the image quality does not deteriorate in the form of streaks or crevices. Further, in the non-exposed area, the toner attached to the photosensitive drum 1 because the suction force by the developing bias is superior to that of the photosensitive drum 1.
T is successively attracted to the developing cleaning device 4 and is collected and cleaned. That is, by applying to the developing roller 10 a developing bias having a potential between the residual potential of the exposed portion and the potential of the non-exposed portion, new toner adheres from the developing roller 10 to the exposed portion, At the same time, the residual toner adhering to the non-image area is attracted to the developing roller 10 from here and is collected. In this case, since the residual toner is small and is dispersed in the form of small dots in the disturbance device 7, the developing / cleaning device 4 can efficiently collect the residual toner, and does not cause a collection failure. In this way, the photosensitive drum 1 is rotated and used repeatedly to obtain one recording image. After the development and cleaning, the toner image is transferred to the sheet 17 at a position facing the transfer roller 5. Hereinafter, similar steps are repeated. According to this embodiment, even if the photosensitive drum 1 having a small diameter is used, not only the occurrence of the memory image which has conventionally occurred but also the cleaning (cleaning) failure can be prevented. . In this example, when 20,000 sheets of A4 size paper with an image area ratio of about 7% were printed, a good image could be obtained to the end without causing poor cleaning. In addition, when a bias voltage is applied to the disturbance device 7, it can be adjusted so as to positively prevent the disturbance effect of the toner and the collection of the toner. That is, contamination of the disturbance device can be prevented. In this case, at the time of non-printing operation of the electrophotographic apparatus, that is, at the time of passing through the non-image area, a bias voltage, for example, about 100 to 300 volts is applied to the elastic brush 18 so that the toner stored in the developer reservoir is exposed from the elastic brush 18. After the toner is forcibly attached to the body drum 1, the toner is conveyed to the developing / cleaning device 4, where the toner can be collected. However, in this case, in order to prevent the photosensitive drum 1 from being charged, the charger 2 is not operated, and a voltage of about 0 to 100 volts is applied to the developing roller 10. As another method of preventing the accumulation of toner in the disturber, there is a method of forming a charged band for adsorbing the toner T attached to the disturber in a non-image area on the photosensitive drum 11. This is caused by the transfer roller 5
Since the charging is performed by charging the photosensitive drum 1 to the polarity opposite to that of the latent image, the reversal developing method is easy to execute. Further, the function is not limited to the transfer roller 5, and the function is the same as that of a non-corona type contact type transfer unit even if it is deformed into a belt shape. Further, in this example, a conductive elastic roller was used as the transfer roller 5. However, even when an insulating elastic roller or belt is used by corona charging, a similar improvement in transfer property is observed. It goes without saying that the same effect can be obtained by incorporating and using such a cleanerless system. In the above embodiment, a non-magnetic one-component developing system was used as an example of miniaturization. Furthermore, the same effect can be expected by using a brush of the same material as the brush used in the disturbance device 7 as the transfer roller and using the same shape, applied voltage and pressing force as the transfer roller as the roller-shaped rotary brush. In this case, in order to remove the toner attached to the rotating brush, there is known a means for separating and removing the toner from the rotating brush by using a rotating electrode to which a bias having a polarity opposite to that applied to the rotating brush is applied. By using, it is possible to maintain stable characteristics for a long period of time. [Effects of the Invention] As described above, according to the present invention, in the simultaneous development cleaning method,
The elastic developing roller carrying the non-magnetic one-component developer charged by friction is pressed against the image carrier to form a nip width, and is rotated with a peripheral speed difference between the roller and the image carrier. And at the same time, the ability to mechanically remove and clean the residual developer is enhanced, the recovery efficiency of the residual developer is increased, and the effect of preventing image memory from being generated can be achieved. Further, after the transfer of the developer image by the transfer means, there is provided image disturbing means for disturbing the developer remaining on the image carrier to form a non-pattern, so that the residual developer on the image carrier is uniformly dispersed. When the elastic developing roller is pressed, the developer on the elastic developing roller is more likely to be uniformly disturbed and slidably contacted, so that the cleaning efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a recording apparatus according to an embodiment of the present invention, and FIG.
FIG. 2 is a graph showing characteristics of roller transfer, and FIG. 2B is a graph showing characteristics of charger transfer. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum (image carrier) 3 ... Laser apparatus (latent image forming means) 4 ... Developing cleaning device (developing cleaning means) 5 ... Transfer roller (transfer means) 7 ... Disturbing device (image disturbing means) T: toner (developer) 10: elastic developing roller 17: paper (transfer material)

Claims (1)

Claims: (1) A latent image forming means for forming an electrostatic latent image of a predetermined polarity on an image carrier, and a non-magnetic member frictionally charged to the same polarity as the predetermined polarity so as to be used for development. An elastic developing roller for carrying a one-component developer is provided, and the elastic developing roller is pressed against the image carrier to form a contact area of a predetermined length between the elastic member and the image carrier by elastic deformation. By rotating the sliding contact with a peripheral speed difference between the image bearing member,
Developing cleaning means for supplying a developer on the elastic developing roller to the electrostatic latent image formed by the latent image forming means and performing reversal development, and removing residual developer on the image carrier; An image forming apparatus comprising: a transfer unit configured to transfer a developer image formed on the image carrier by the developing cleaning unit onto a transfer material. (2) a latent image forming means for forming an electrostatic latent image of a predetermined polarity on a rotating image carrier, and a non-magnetic one-component developer frictionally charged to the same polarity as the predetermined polarity so as to be used for development An elastic developing roller for carrying the image, and pressing the elastic developing roller against the image carrier so as to make sliding contact with the image carrier, thereby forming an electrostatic latent image formed by the latent image forming means on the elastic developing roller. A developer cleaning unit that removes the residual developer on the image carrier at the same time as supplying the developer and performing the reversal development; and bringing the elastic developing roller into sliding contact with the image carrier. Rotating means for rotating the elastic developing roller while providing a peripheral speed difference with the peripheral speed of the image carrier; and an elastic developing roller for pressing the elastic developing roller against the image carrier. 20g / cm or more Loading means for applying a load of 120 g / cm; transfer means for transferring a developer image formed on the image carrier by the developing and cleaning means onto a material to be transferred; and after transferring the developer image by the transfer means. Image disturbing means for disturbing the developer remaining on the image carrier to form a non-pattern. (3) a latent image forming means for forming an electrostatic latent image of a predetermined polarity on a rotating image carrier; and a non-magnetic one-component developer frictionally charged to the same polarity as the predetermined polarity for use in development. An elastic developing roller for carrying the image, and pressing the elastic developing roller against the image carrier so as to make sliding contact with the image carrier, thereby forming an electrostatic latent image formed by the latent image forming means on the elastic developing roller. A developer cleaning unit that removes the residual developer on the image carrier at the same time as supplying the developer and performing the reversal development; and bringing the elastic developing roller into sliding contact with the image carrier. Rotating means for rotating the elastic developing roller at a peripheral speed of 1.5 to 4 times the peripheral speed of the image carrier; and an elastic developing roller for pressing the elastic developing roller against the image carrier. 20g / cm as line weight An image, comprising: weighting means for applying a weight of 120 g / cm; and transfer means for transferring a developer image formed on the image carrier by the developing and cleaning means onto a material to be transferred. Forming equipment.