Patent Application
20210271183
An image forming apparatus includes, for example, a conveying device which conveys a sheet, an image carrier on which an electrostatic latent image is formed, a developing device which develops the electrostatic latent image, a transfer device which transfers a toner image onto a sheet, a fixing device which fixes the toner image onto the sheet, and a discharge device which discharges the sheet.
Hereinafter, an example imaging system will be described with reference to the drawings. The imaging system is, for example, an image forming apparatus such as a printer, but may be a component which constitutes the image forming apparatus. For example, the imaging system may be a developing device used in the image forming apparatus or the like. In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted.
An image forming apparatus 1 illustrated in
The conveying device 10 may convey the sheet P as a print medium having an image formed thereon on a conveying route R1. The sheet P may be accommodated in a cassette K in a stacked state and is picked up and conveyed by the feeding roller 11. The conveying device 10 may allow the sheet P to reach a transfer nip portion R2 through the conveying route R1, for example, at a timing in which the toner image transferred to the sheet P reaches the transfer nip portion R2.
Four developing devices 20 may be provided for respective colors. Each developing device 20 may include a developing agent carrier 24 which carries toner on the image carrier 40. In the developing device 20 a two-component developing agent including toner and carrier may be used as the developing agent. In the developing device 20, the toner and the carrier may be adjusted and mixed to have a desired mixing ratio so that the toner is uniformly dispersed. Accordingly, the developing agent having an optimal charge amount may be adjusted. The developing agent may be carried on the developing agent carrier 24. The developing agent carrier 24 may rotate to convey the developing agent to a region facing the image carrier 40. Then, the toner in the developing agent carried on the developing agent carrier 24 may transfer to the peripheral surface of the image carrier 40 to form the electrostatic latent image on the image carrier 40, so that the electrostatic latent image is developed.
The transfer device 30 may convey the toner image formed by the developing device 20 to the transfer nip portion R2. The transfer device 30 may include a transfer belt 31 onto which the toner image is primarily transferred from the image carrier 40, suspension rollers 34, 35, 36, and 37 which suspend the transfer belt 31, a primary transfer roller 32 which sandwiches the transfer belt 31 along with the image carrier 40, and a secondary transfer roller 33 which sandwiches the transfer belt 31 along with the suspension roller 37.
The transfer belt 31 may be an endless belt which moves in a circulating manner by the suspension rollers 34, 35, 36, and 37. The suspension rollers 34, 35, 36, and 37 may be rollers which is rotatable about respective axes. The suspension roller 37 may be a drive roller which is rotationally driven to rotate about its axis. The suspension rollers 34, 35, and 36 may be driven rollers which rotate in a following manner in accordance with the rotational driving of the suspension roller 37. The primary transfer roller 32 may be provided to press the image carrier 40 from the inner peripheral side of the transfer belt 31. The secondary transfer roller 33 may be disposed in parallel to the suspension roller 37 with the transfer belt 31 interposed therebetween and may be provided to press the suspension roller 37 from the outer peripheral side of the transfer belt 31. Accordingly, the secondary transfer roller 33 may form the transfer nip portion R2 between the secondary transfer roller and the transfer belt 31.
The image carrier 40 may also be referred to as an electrostatic latent image carrier, a photosensitive drum, or the like. Four image carriers 40 may be provided for respective colors. Each image carrier 40 may be located along the trajectory (in the movement direction) of the transfer belt 31. For example, the developing device 20, a charging roller 41, an exposure unit 42, and a cleaning device 43 may be provided around the image carrier 40.
The charging roller 41 may be adapted to uniformly charge the surface of the image carrier 40 to a predetermined potential. The charging roller 41 may rotate to follow the rotation of the image carrier 40. The exposure unit 42 may expose the surface of the image carrier 40 charged by the charging roller 41 in response to an image formed on the sheet P. Accordingly, a potential of a portion exposed by the exposure unit 42 in the surface of the image carrier 40 may change so that the electrostatic latent image is formed. Four developing devices 20 may generate the toner image by developing the electrostatic latent image using the toner supplied from a toner tank N provided to face each developing device 20. Each toner tank N may be charged with each of magenta, yellow, cyan, and black toners. The cleaning device 43 may collect the toner remaining on the image carrier 40 after the toner image formed on the image carrier 40 is primarily transferred to the transfer belt 31.
The fixing device 50 may melt and fix the toner image, secondarily transferred from the transfer belt 31 to the sheet P, to the sheet P by allowing the sheet P to pass through a fixing nip portion in a heated and pressed state. The fixing device 50 may include a heating roller 52 which heats the sheet P and a pressing roller 54 which rotationally drives the heating roller 52 in a pressed state. Each of the heating roller 52 and the pressing roller 54 may be formed in a cylindrical shape and the heating roller 52 may include therein a heat source such as a halogen lamp. The fixing nip portion corresponding to a contact region may be provided between the heating roller 52 and the pressing roller 54, to melt and fix the toner image to the sheet P when the sheet P passes through the fixing nip portion.
The discharge device 60 may include discharge rollers 62 and 64 to discharge the sheet P onto which the toner image is fixed by the fixing device 50 to the outside of the apparatus.
Subsequently, an example of a printing process using the example image forming apparatus 1 will be described. When an image signal of a recording target image is input to the image forming apparatus 1, a control unit (not illustrated) of the image forming apparatus 1 picks up and conveys the sheet P stacked on the cassette K by rotating the feeding roller 11. Then, the surface of the image carrier 40 is uniformly charged to a predetermined potential by the charging roller 41 based on the received image signal (charging process). Subsequently, a laser beam is irradiated to the surface of the image carrier 40 by the exposure unit 42 so that the electrostatic latent image is formed (exposing process).
In the developing device 20, the electrostatic latent image is developed so that the toner image is formed (developing process). The toner image which is formed in this way is primarily transferred from the image carrier 40 to the transfer belt 31 in a region in which the image carrier 40 faces the transfer belt 31 (transfer process). The toner images formed on the four image carriers 40 are sequentially laminated on the transfer belt 31 so that one laminated toner image is formed. Then, the laminated toner image is secondarily transferred to the sheet P conveyed from the conveying device 10 in the transfer nip portion R2 in which the suspension roller 37 faces the secondary transfer roller 33.
The sheet P onto which the laminated toner image is secondarily transferred is conveyed to the fixing device 50. Then, the fixing device 50 melts and fixes the laminated toner image to the sheet P by heating and pressing the sheet P between the heating roller 52 and the pressing roller 54 at the time of allowing the sheet P to pass through the fixing nip portion (fixing process). Subsequently, the sheet P is discharged to the outside of the image forming apparatus 1 by the discharge rollers 62 and 64.
As illustrated in
The trapping device 70 may be provided by an electrostatic precipitator including an ionizer 71, a particle filter 72, an exhaust fan 73, and a controller 74. The ionizer 71 may include a first electrode (a discharge electrode) 75 and a pair of second electrodes (counter electrodes) 76. A high voltage is applied from a high-voltage power source (not illustrated) to the first electrode 75. The first electrode 75 may include a plurality of protrusions 75a for electric discharge. The plurality of protrusions 75a may be arranged at the same intervals. For example, the protrusions 75a may be equally spaced apart. Each protrusion 75a may be formed in a saw blade shape or a needle shape. The pair of second electrodes 76 may be grounded and disposed to face each other. The first electrode 75 may be disposed between the pair of second electrodes 76.
In the example ionizer 71, when a voltage applied to the first electrode 75 is less than a predetermined value, no current flows between the first electrode 75 and the second electrode 76. However, when a voltage applied to the first electrode 75 is equal to or greater than a predetermined value, an electric discharge phenomenon occurs such that a current flows between the first electrode 75 and the second electrode 76. The ionizer 71 charges the particles 5 passing between the first electrode 75 and the second electrode 76 by the flowing current. As the voltage applied to the first electrode 75 increases, the amount (energization amount) of the current flowing between the first electrode 75 and the second electrode 76 increases.
The magnitude (or amount) of the voltage applied to the first electrode 75 is controlled by the controller 74. The controller 74 may perform a current control by controlling the high-voltage power source. That is, the controller 74 controls the magnitude of the voltage applied to the first electrode 75 to achieve a target value for the amount of the current flowing between the first electrode 75 and the second electrode 76. For example, the controller 74 may control the magnitude of the voltage applied to the first electrode 75 by varying, for example, a duty ratio of a PWM signal input to the high-voltage power source.
The leading end portion of the first electrode 75 may deteriorate with use. When the leading end portion deteriorates, the amount of the current flowing between the first electrode 75 and the second electrode 76 may change even when the voltage application amount is the same. In the example ionizer 71, the current amount can be stably adjusted to a target value even when the leading end portion deteriorates by performing the constant current control.
The particle filter 72 may include a lamination structure of polymer sheets subjected to an electret treatment, that include a plurality of tubular ventilation paths 72a. The surface of the particle filter 72 may be semi-permanently charged. Consequently, the particle filter 72 can collect the particles 5 charged by the ionizer 71. The electret treatment may be a treatment of solidifying a polymer material heated and melted while applying a high voltage thereto so as to have a structure for maintaining charging on the polymer material. For example, as illustrated in
The exhaust fan 73 may be an airflow generator which generates an airflow 7 for carrying the particles 5. The exhaust fan 73 may be disposed on the opposite side to the ionizer 71 with respect to, for example, the particle filter 72, to generate the airflow 7 so that the particles 5 charged by the ionizer 71 are carried to the particle filter 72.
The controller 74 may be electrically connected to the trapping device 70 and control the operation of the trapping device 70. The controller 74 may control the magnitude of the voltage applied to the first electrode 75 and control the operation of the exhaust fan 73. The controller 74 may be configured as a computer including a processor 74a such as a central processing unit (CPU) and a storage unit 74b such as a read only memory (ROM) and a random access memory (RAM). The storage unit 74b may also be referred to herein as storage or non-transitory storage device.
The storage unit 74b may store a current control program C. The storage unit 74b may be a non-transitory computer readable storage device (a storage medium) which stores the current control program C. The controller 74 is adapted to carry out a current control as described further below, by reading the current control program C to the processor 74a and executing the program.
As illustrated in
The medium sensor 80 may include a light emitting portion 81, a first light receiving portion 82, and a second light receiving portion 83. The light emitting portion 81 may include a light emitting element which irradiates light L1 to the sheet P conveyed by the conveying device 10. The first light receiving portion 82 may include a light receiving element which detects light L2 reflected by the sheet P. The second light receiving portion 83 may be a light receiving element which detects light L3 transmitted through the sheet P. In the medium sensor 80, at least one of the water content and the thickness of the sheet P can be detected based on the intensity of the light L3 detected by the second light receiving portion 83 and the intensity of the light L2 detected by the first light receiving portion 82. It is possible to calculate the water content of the sheet P by multiplying the water content by the basis weight.
Referring to
The controller 74 controls the amount of the current flowing between the first electrode 75 and the second electrode 76 to a first amount A1 during a period from the time T1 to the time T2. The time T2 is, for example, 900 seconds (15 minutes) after the time T0. The first amount A1 is greater than zero. For example, first amount A1 may be 30 μA.
The controller 74 controls the amount of the current flowing between the first electrode 75 and the second electrode 76 to a second amount A2 during a period from the time T2 to the time T3. That is, the controller 74 increases the current amount from the first amount A1 to the second amount A2 during the printing operation. The controller 74 maintains the current amount to the second amount A2 until the printing operation ends. The second amount A2 is greater than the first amount A1. For example, the second amount A2 may be 90 μA.
The controller 74 controls the amount of the current flowing between the first electrode 75 and the second electrode 76 to a third amount A3 during a period from the time T3 to the time T4. That is, the controller 74 controls the current amount to the third amount A3 for a predetermined time (for example, 30 seconds) after the printing operation ends. This follows from the emission of UFP even during the period after the printing operation ends. The time T4 is, for example, 1170 seconds (19 minutes) after the time T0. The third amount A3 is less than the second amount A2. In this example, the third amount A3 is the same as the first amount A1, but may be greater than the first amount A1. The controller 74 controls the current amount to zero during a period after the time T4.
The controller 74 may operate the exhaust fan 73 during a period from the time T1 to the time T4. That is, the controller 74 operates the exhaust fan 73 throughout a period in which the amount of the current flowing between the first electrode 75 and the second electrode 76 is the first amount A1, the second amount A2, and the third amount A3. In this example, the controller 74 operates the exhaust fan 73 at the same intensity during a whole period from the time T1 to the time T4. For example, the controller 74 maintains a duty ratio of a PWM signal input to the exhaust fan 73 to 100% during a whole period from the time T1 to the time T4.
As described above, in this example current control, the controller 74 controls the amount of the current flowing between the first electrode 75 and the second electrode 76 during the printing operation based on a time elapsed (or an elapsed time) during the printing operation corresponding to the print state indicator associated with the printing operation. In this case, the print state indicator indicates the degree of progress (or progress degree) of the printing operation.
As shown in
It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail.
For example, in the above-described current control, the number of sheets to be printed, the printing period PF, the time T1, the time T2, the time T3, the time T4, the first amount A1, the second amount A2, and the third amount A3 are merely examples and can be appropriately set and modified in response to a printing condition or the like. In the above-described examples, the controller 74 controls the current amount based on the time elapsed during the printing operation, but in some examples, the controller 74 may control the current amount based on the consumed toner amount during the printing operation. For example, the controller 74 may increase the current amount from the first amount A1 to the second amount A2 when the toner consumption amount exceeds a first threshold value. The controller 74 may decrease the current amount from the second amount A2 to the third amount A3 when the toner consumption amount exceeds a second threshold value greater than the first threshold value. That is, the controller 74 may determine the degree of progress (or progress degree) of the printing operation based on the elapsed time or may determine the progress degree of the printing operation based on the toner consumption amount. The toner consumption amount may be calculated based on, for example, the detection result of the sensor detecting the remaining toner amount or the printing condition or the like.
The controller 74 may control the intensity (e.g. an amount of airflow generation) of the exhaust fan 73 based on the progress degree of the printing operation. For example, the controller 74 may increase the current amount from the first amount A1 to the second amount A2 and increase the intensity of the exhaust fan 73 from a first intensity to a second intensity. The controller 74 may decrease the current amount from the second amount A2 to the third amount A3 and decrease the intensity of the exhaust fan 73 from the second intensity to the third intensity.
Referring to
The controller 74 changes the current amount in response to a comparison (or comparison result) of the area ratio of the sheet P and the first threshold value. For example, the controller 74 may control the current amount when the area ratio is equal to or greater than the first threshold value to a large amount as compared with a case in which the area ratio is less than the first threshold value. This follows from the increase of the toner consumption amount and of the UFP emission amount when the area ratio increases. The first threshold value may be 20%, for example. The area ratio can be calculated, for example, based on the image signal of the recording target image input to the image forming apparatus 1.
The controller 74 may vary the current amount in response to a comparison (or comparison result) of the water content of the sheet P to a second threshold value. For example, the controller 74 controls the current amount when the water content is equal to or greater than the second threshold value to a large amount as compared with the current amount when the water content is less than the second threshold value. This follows from the increase of the amount of vapor generated in the fixing device 50 and of the UFP emission amount when the water content increases. The second threshold value is, for example, 5%. The controller 74 changes the current amount in response to a comparison (or comparison result) of the basis weight of the sheet P and a third threshold value. For example, the controller 74 controls the current amount when the basis weight is equal to or greater than the third threshold value to a large amount as compared with the current amount when the basis weight is less than the third threshold value. This follows from the increase of the heating amount of the fixing device 50 and of the UFP emission amount when the basis weight (thickness) increases. The third threshold value may be 75 g/m2, for example. The water content and the basis weight are calculated based on the detection result of the medium sensor 80, but may be calculated based on the information input to the image forming apparatus 1.
For example, as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-148526 | Aug 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/041577 | 7/12/2019 | WO | 00 |
