Patent Grant
10025237
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2016-172250 filed Sep. 2, 2016.
The invention relates to an image forming apparatus and a recording medium transport apparatus.
According to an aspect of the invention, an image forming apparatus includes
a transport unit configured to pinch and transport a recording medium at a first transport speed,
a fixing unit configured to fix an image formed on the recording medium while pinching and transporting the recording medium, which is transported by the transport unit, at a second transport speed,
a driving unit configured to drive the fixing unit,
a detector configured to detect a load of the driving unit, and
a controller configured to perform a control to adjust a speed difference between the first transport speed and the second transport speed with respect to a subsequently transported recording medium when the load becomes larger than a reference value after a peak value of the load when the recording medium enters the fixing unit is detected by the detector.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
Hereinafter, an exemplary embodiment for carrying out the invention will be described in detail with reference to the accompanying drawings.
A configuration of an image forming apparatus 10 according to the present exemplary embodiment will be described with reference to
(Overall Configuration)
As illustrated in
In addition, at the center side of the apparatus main body 10A, image forming units 16 of respective colors, which respectively form toner images, are arranged to be spaced apart from each other in an inclined direction relative to the horizontal direction. In addition, at the vertically upper side of the image forming units 16 of respective colors, a primary transfer unit 18 is provided to which toner images formed in the image forming units 16 of respective colors are multiply transferred.
Further, at a lateral side (the left side of
A fixing device 24 is installed at the downstream side of the secondary transfer roller 22 in the transport direction of the recording medium P (hereinafter simply referred to as a “transport direction”). The fixing device 24 fixes the toner images, which have been transferred to the recording medium P, to the recording medium P by heat and pressure.
In addition, at the downstream side with reference to the fixing device 24 in the transport direction, a discharge roller 28 is installed to discharge the recording medium P having the toner images fixed thereto to a discharge unit 26 provided in the upper portion of the apparatus main body 10A of the image forming apparatus 10.
Meanwhile, the supply transport unit 30 is installed at a vertically lower and lateral side of the image forming units 16 to supply and transport the recording medium P. In addition, at the vertically upper side of the primary transfer unit 18, four toner cartridges 14K to 14Y for respective colors are arranged side by side in the apparatus width direction. The toner cartridges 14K to 14Y are detachable from the apparatus main body 10A from the front side of the apparatus main body 10A and are filled with a toner to be replenished to a developing device 38 to be described below. The toner cartridges 14 of respective colors have a columnar shape extending in the apparatus depth direction. Each toner cartridge 14 is connected to corresponding one of the developing devices 38 of respective colors through a supply pipe (not illustrated).
(Image Forming Unit)
As illustrated in
In addition, the image forming unit 16 includes a light emitting diode (LED) head 32 that irradiates the surface of the charged image carrier 34 with exposure light that forms an electrostatic latent image. In addition, the image forming unit 16 includes the developing device 36 that develops an electrostatic latent image, which is formed via the irradiation of exposure light by the LED head 32, using a developer (in the present exemplary embodiment, a negatively charged toner) so as to visualize the electrostatic latent image as a toner image. In addition, the image forming unit 16 includes a cleaning blade (not illustrated) that cleans the surface of the image carrier 34.
A developing roller 39 is disposed in the developing device 38 to face the image carrier 34, and the developing device 38 develops an electrostatic latent image, which is formed on the image carrier 34, using the developing roller 39 and a developer to visualize the electrostatic latent image as a toner image.
In addition, the charging unit 36, the LED head 32, the developing roller 39, and the cleaning blade are arranged in this order from the upstream side to the downstream side of the image carrier 34 in the rotation direction (the counterclockwise direction in the example of
(Transfer Unit (Primary Transfer Unit and Secondary Transfer Roller))
The primary transfer unit 18 includes an endless intermediate transfer belt 42 and a driving roller 46. The intermediate transfer belt 42 is wound on the driving roller 46. The driving roller 46 is rotationally driven by a motor 112 (see
With this configuration, the toner images of respective colors of Y, M, C, and K, which are sequentially formed on the image carriers 34 of the image forming units 16 of respective colors, are multiply transferred to the intermediate transfer belt 42 by the primary transfer rollers 52 of respective colors.
In addition, a cleaning blade 56 is disposed opposite to the driving roller 46 with the intermediate transfer belt 42 being interposed therebetween to come in contact with the surface of the intermediate transfer belt 42 so as to clean the surface of the intermediate transfer belt 42.
In addition, the secondary transfer roller 22 is installed opposite to the auxiliary roller 50 with the intermediate transfer belt 42 being interposed therebetween to transfer the toner images, which have been transferred to the intermediate transfer belt 42, to the recording medium P that is being transported. The secondary transfer roller 22 is grounded, and the auxiliary roller 50 forms a counter electrode of the secondary transfer roller 22. When a secondary transfer voltage is applied to the auxiliary roller 50, the toner images are transferred to the recording medium P. At this time, the secondary transfer roller 22 and the intermediate transfer belt 42 are an exemplary transport unit that pinches and transports the recording medium P.
(Supply Transport Unit)
The supply transport unit 30 is disposed at the vertically lower side of the image forming units 16 within the apparatus main body 10A, and includes a paper feeding member 62 in which plural recording media P are loaded.
In addition, the supply transport unit 30 includes a Paper feeding roller 64 that sends out the recording media P, which is loaded in the paper feeding member 62, to the transport path 60, a separation roller 66 that separates the recording media P, which are sent out by the paper feeding roller 64, one by one, and a registration roller 68 that adjusts the transport timing of the recording media P. In addition, the respective rollers are arranged in this order from the upstream side to the downstream side of the transport direction.
With this configuration, the recording media P supplied from the paper feeding member 62 are sent out at a predetermined timing to a contact portion (secondary transfer position) between the intermediate transfer belt 12 and the secondary transfer roller 22 by the registration roller 68 that rotates.
The fixing device 24 according to the present exemplary embodiment includes a heating belt 24A and a pressure roller 24B. The fixing device 24 is a so-called induction heating (IH) fixing device that causes the heating belt 24A to generate heat using electromagnetic induction. In addition, the pressure roller 24B is driven (rotated) by a motor 122 (see
With the above configuration, the recording medium P transported to the fixing device 24 is heated and pressurized by the fixing device 24 so that a toner image is fixed to one surface (image formation surface) of the recording medium P. Here, the fixing device 24 is an exemplary fixing unit that fixes an image formed on the recording medium P while pinching and transporting the recording medium P that is being transported by the secondary transfer roller 22 and the intermediate transfer belt 42.
In addition, the supply transport unit 30 includes a duplex transport device 70. For a recording medium P having a toner image fixed to one surface thereof by the fixing device 24, the duplex transport device 70 is used to form a toner image on the other surface of the recording medium P, rather than directly discharging the recording medium P to the discharge unit 26 by the discharge roller 28.
The duplex transport device 70 includes a duplex transport path 72 and transport rollers 74 and 76. In the duplex transport path 72, the record sing medium P is reversed and transported from the discharge roller 28 toward the registration roller 68. The transport rollers 74 and 76 transport the recording medium P along the duplex transport path 172.
(Others)
The image forming apparatus 10 includes a medium detection sensor 82 installed at the upstream side of the fixing device 24 along the transport path 60. The medium detection sensor 82 according to the present exemplary embodiment is, for example, a reflective sensor that includes a set of a light emitting element and a light receiving element. The medium detection sensor 82 irradiates from the light emitting element to a detection position on the transport path 60 which corresponds to the installation position thereof. In addition, the medium detection sensor 82 outputs a signal (hereinafter, referred to as a “detection signal”) of the signal level according to the quantity of light received from the light receiving element. During the period for which the recording medium P passes the detection position, the light irradiated from the light emitting element is reflected by the recording medium P. Thus, detection signals output from the medium detection sensor 82 during the period for which the recording medium P passes the detection position are different in signal level from those output from the medium detection sensor 82 during the period for which the recording medium P does not pass the detection position.
In this way, the present exemplary embodiment employs the reflective sensor as the medium detection sensor 82. It should be noted that the medium detection sensor 82 is not limited thereto, but may be other sensors such as, for example, a transmissive sensor.
(Image Forming Process)
First, tone data of respective colors are sequentially output from the image processing unit 12 to LED heads 32 of respective colors. Then, by the LED heads 32, exposure lights according to the input tone data are emitted. The surfaces of the image carriers 34 charged by the charging units 36 are irradiated with the exposure lights that are emitted from the LED heads 32, respectively. Thus, electrostatic latent images are formed on the surfaces of the image carriers 34. The electrostatic latent images formed on the image carriers 34 are developed by the developing devices 38 of respective colors, respectively, and are visualized as toner images of respective colors of Y, M, C, and K, respectively.
In addition, the toner images of respective colors formed on the image carriers 34 are multiply transferred to the circulating intermediate transfer belt 42 by the primary transfer rollers 52 of the primary transfer unit 18.
The toner images of respective colors, which have been multiply transferred to the intermediate transfer belt 42, are secondarily transferred to the recording medium P at secondary transfer position by the secondary transfer roller 22 when the recording medium P has been transported to the secondary transfer position along the transport path 60 from the paper feeding member 62 by the paper feeding roller 64, the separation roller 66, and the registration roller 68.
In addition, the recording medium P, to which the toner image has been transferred, is transported to the fixing device 24. In addition, the toner image is fixed to the recording medium P by the fixing device 24. Then, the recording medium P, to which the toner image has been fixed, is discharged to the discharge unit 26 by the discharge roller 28.
Meanwhile, when forming images on the opposite sides of recording medium P, the recording medium P, to one surface (front surface) of which the toner image has been fixed by the fixing device 24, is not directly discharged to the discharge unit 26 by the discharge roller 28. In this case, the transport direction of the recording medium P is switched by reversely rotating the discharge roller 28. Then, the recording medium P is transported along the duplex transport path 72 by the transport rollers 74 and 76.
The recording medium P transported along the duplex transport path 72 is reversed and transported again to the registration roller 68. Then, after a toner image is transferred and fixed to the other surface (back surface) of the recording medium P, the recording medium P is discharged to the discharge unit 26 by the discharge roller 28.
Next, a configuration of main parts of an electrical system in the image forming apparatus 10 according to the present exemplary embodiment will be described with reference to
As illustrated in
In addition, the image forming apparatus 10 includes a communication line interface (I/F) unit 108 that performs transmission and reception of communication data to and from an external device. In addition, the image forming apparatus includes an operation display 110 that receives an instruction with respect to the image forming apparatus 10 from a user and displays various information about the operation situation of the image forming apparatus 10 and the like to the user. In addition, the operation display 110 includes, for example, a display button that realizes reception of an operation instruction via execution of a program, a display provided with a touch panel on a display surface on which various information are displayed, and hardware keys such as a numeric keypad or a start button.
In addition, the image forming apparatus 10 includes a torque detector 124, which is an exemplary detector that detects the load (torque) of the motor 122, which is driven to rotate the pressure roller 24B. The torque detector 124 according to the present exemplary embodiment is connected to the motor 122, and detects the torque of the motor 122 as a value of a current that flows to the motor 122.
In addition, a configuration of the torque detector 124 according to the present exemplary embodiment is not specifically limited so long as it can detect the torque of the motor 122. For example, as the torque detector 124, a configuration in which the current value is detected by measuring a voltage value across a shunt resistor may be used. In addition, for example, as the torque detector 124, a configuration in which resistors are install ed on a path along which current flows to the motor 122 and a voltage value between the resistors is measured to detect a current value may be applied. In addition, for example, as the torque detector 124, a configuration in which a current sensor using a Hall element is installed on a path along which current flows to the motor 122 to detect a current value may be applied. In addition, the torque detector 124 may be configured to convert the detected current value into a voltage value and to output the voltage value. In addition, for example, as the torque detector 124, a torque detection detector that detects the torque of the motor 122 may be applied.
In addition, the image forming apparatus 10 is provided with an image forming unit 116 that includes constituent parts that perform various processing related to image formation on the recording medium P such as the image forming unit 16 and the primary transfer unit 18 described above. In addition, respective parts of the CPU 100, the ROM 102, the RAM 104, the memory 106, the communication line I/F unit 108, the operation display 110, the motor 112, the motor 122, the torque detector 124, the image forming unit 116, and the medium detection sensor 82 are connected to one another via buses 118 such as an address bus, a data bus, and a control bus.
With the above configuration, the image forming apparatus 10 according to the present exemplary embodiment performs, by the CPU 100, access to the ROM 102, the RAM 104, and the memory 106, and transmission and reception of communication data to and from an external device via the communication line I/F unit 108. In addition, the image forming apparatus 10 performs, by the CPU 100, acquisition of various instruction information via the operation display 110 and display of various information with respect to the operation display 110. In addition, the image forming apparatus 10 controls the rotation speed of the driving roller 46, that is, the transport speed (hereinafter, referred to as a “first transport speed”) of the recording medium P by the secondary transfer roller 22 and the intermediate transfer belt 42 by controlling the motor 112 using the CPU 100.
In addition, the image forming apparatus 10 controls the rotation speed of the pressure roller 24B, that is, the transport speed (hereinafter, referred to as a “second transport speed”) of the recording medium P by the fixing device 24 by controlling the motor 122 using the CPU 100. In addition, the image forming apparatus 10 performs, by the CPU 100, acquisition of a current value output from the torque detector 124 and control of the image forming unit 116.
In addition, the image forming apparatus 10 acquires, by the CPU 100, a detection signal output from the medium detection sensor 82. Thus, the image forming apparatus 10, by the CPU 100, detects whether or not the recording medium P passes a detection position using the medium detection sensor 82 based on the signal level of the acquired detection signal.
In the image forming apparatus 10 according to the present exemplary embodiment, the current value detected by the torque detector 124 largely varies when the recording medium P enters the fixing device 24 or is discharged from the fixing device 24.
As an example, as illustrated in
Meanwhile, in the image forming apparatus 10 according to the present exemplary embodiment, the motor 112 and the motor 122 are controlled in such a manner that the first transport speed is faster than the second transport speed by predetermined speed difference. Thus, as an example, as a result of the recording medium P being bent by a predetermined bending amount (so-called a loop amount) as represented by the solid line in
However, even if the motor 112 and the motor 122 are controlled as described above, the speed difference between the first transport speed and the second transport speed may not become a predetermined speed difference due to environmental conditions such as the kind of the recording medium P, temperature, and humidity, and the state changes of respective constituent elements of the image forming apparatus 10 due to the aging.
In the case where the speed difference between the first transport speed and the second transport speed is larger than the predetermined speed difference, that is, in the case where the second transport speed is excessively faster than the first transport speed, as indicated by the dashed line in
Subsequently, the change of the current value, which is detected by the torque detector 124 in the case where the speed difference between the first transport speed and the second transport speed is larger than the predetermined speed difference, will be described with reference to
In addition, hereinafter, the period from the time t1 to the time t2 will be referred to as the period A, and the period from the time t2 to the time t3 will be referred to as the period B. That is, the period A is the period for which the recording medium P is transported by both of the secondary transfer roller 22 and the intermediate transfer belt 42 and the fixing device 24. In addition, the period B is the period for which the recording medium P is transported by the fixing device 24 among the secondary transfer roller 22, the intermediate transfer belt 42, and the fixing device 24.
As an example, as illustrated in
Subsequently, the change of the current value, which is detected by the torque detector 124 in the case where the speed difference between the first transport speed and the second transport speed is smaller than the predetermined speed difference, will be described with reference to
As an example, as illustrated in
Thus, in the image forming apparatus 10 according to the present exemplary embodiment, in the case where the current value in the period A after the peak value of the current value when the recording medium P enters the fixing device 24 is detected by the torque detector 124 is larger than the reference value RV, the speed difference between the first transport speed and the second transport speed of the subsequently transported recording medium P is adjusted.
Specifically, before the period a1 has elapsed, that is, when the current value in the period a1 is larger than the reference value RV, the image forming apparatus 10 causes the second transport speed of the subsequently transported recording medium P to be slower than the current second transport speed. In addition, in this case, based on the following Table 1, the image forming apparatus 10 increases the degree of making the second transport speed is made slower as the length of the recording medium P in the transport direction (in Table 1, the size of the recording medium P is indicated) increases and the average value of the current values in the period A increases.
As shown in Table 1, the image forming apparatus 10 according to the present exemplary embodiment classifies the average value of the current values in the period A into three levels of small, medium, and large. In addition, the image forming apparatus 10 makes the second transport speed slower than the current second transport speed by a proportion shown in Table 1 in accordance with the combination of the size of the recording medium P and the average value of the current values. For example, in the case where the size of the recording medium P is A4 and the average value of the current values is small, the image forming apparatus 10 makes the second transport slower than the current second transport speed by 1%.
In addition, after the period a1 has expired, that is, when the current value in the period a2 becomes larger than the reference value RV, the image forming apparatus 10 causes the second transport speed of the subsequently transported recording medium P to be faster than the current second transport speed. In addition, in this case, based on Table 1, the image forming apparatus 10 increases the degree of making the second transport speed faster as the length of the recording medium P in the transport direction increases and the average value of the current values in period a2 increases. For example, in the case where the size of the recording medium P is A4 and the average value of the current values is small, the image forming apparatus 10 causes the second transport speed to be faster than the current second transport speed by 1%.
Subsequently, the action of the image forming apparatus 10 according to the present exemplary embodiment will be described with reference to
In step 130 of
In addition, in the present exemplary embodiment, the acquisition processing of the current value output from the torque detector 124 in step 130 is adapted to acquire the current value at a predetermined acquisition interval (sampling rate) (an interval of 10 ms in the present exemplary embodiment).
In step 134, the CPU 100 derives the average value of the current values in the period B in the time series data of the current values acquired by the repetitive processing of step 130, as the reference value RV. In the next step 136, the CPU 100 derives the average value of the current values in the period A in the time series data of the current values acquired by the repetitive processing of step 130.
In the next step 138, the CPU 100 determines whether or not the average value derived in step 136 is larger than the reference value RV derived in step 134. When a negative determination is made, the CPU 100 proceeds to step 150, and when a positive determination is made, the CPU 100 proceeds to step 140. In addition, in this step 138, the CPU 100 may determine whether or not the average value derived in step 136 is larger than a value, which is acquired by adding a predetermined margin to the reference value RV derived in step 134.
In step 140, the CPU 100 derives the average value of the current values in the period a1 in the time series data of the current values acquired by the repetitive processing of step 130. In step 142, the CPU 100 determines whether or not the average value derived in step 140 is larger than the reference value RV derived in step 134. When a negative determination is made, the CPU 100 proceeds to step 146, and when a positive judgment is made, the CPU 100 proceeds to step 144. In addition, in this step 142, the CPU 100 may determine whether or not the average value derived in step 140 is larger than a value, which is acquired by adding a predetermined margin to the reference value RV derived in step 134.
In step 144, as described above, based on Table 1, the CPU 100 derives the second transport speed, which is made slower as the length of the recording medium P in the transport direction increases and the average value of the current values in the period A derived in step 136 increases.
Meanwhile, in step 146, the CPU 100 derives the average value of the current values in the period a2 n the time series data of the current values acquired by the repetitive processing of step 130. In addition, as described above, based on Table 1, the CPU 100 derives the second transport speed, which is made faster as the length of the recording medium P in the transport direction increases and the derived average value of the current values in the period a2 increases.
In step 148, the CPU 100 performs control to change the second transport speed into the second transport speed derived in step 144 or step 146, performs a control to form an image on the second and subsequent recording media P, and thereafter terminates this speed-difference adjustment processing.
Meanwhile, in step 150, the CPU 100 performs control to form an image on the second and subsequent recording media P without changing the transport speed of the recording medium P, and thereafter terminates this speed-difference adjustment processing.
Meanwhile, the present exemplary embodiment has been described with reference to the case of using the IH type fixing device, but is not limited thereto. For example, a fixing device of another type using a halogen lamp or the like may be used.
In addition, the exemplary embodiment has been described with reference to the case of adjusting the second transport speed when the speed difference between the first transport speed and the second transport speed is adjusted, but is not limited thereto. For example, the first transport speed may be adjusted, and both the first transport speed and the second transport speed may be adjusted.
In the case of adjusting the first transport speed, for example, when the average value of the current values in the period A and the average value of the current values in the period a1 are larger than the reference value RV, there is illustrated an example in which the first transport speed is made faster as the average value of the current values in the period A increases. In addition, in the case of adjusting the first transport speed, for example, when the average value of the current values in the period A is larger than the reference value RV and the current value in the period a1 is equal to or less than the reference value RV, there is illustrated an example in which the first transport speed is made slower as the average value of the current values in the period a2 is increases.
In addition, in the case of adjusting both the first transport speed and the second transport speed, for example, when the average value of the current values in the period A and the average value of the current values in the period a1 are larger than the reference value RV, there is illustrated an example in which the first transport speed is made faster and the second transport speed is made faster as the average value of the current values in the period A increases. In addition, in this case, there is illustrated an example in which both the first transport speed and the second transport speed are adjusted so that the speed difference after the first transport speed and the second transport speed are adjusted is equal to the speed difference after the second transport speed is adjusted in the exemplary embodiment.
In addition, in the case of adjusting both the first transport speed and the second transport speed, for example, when the average value of the current values in the period A is larger than the reference value RV and the average value of the current values in the period a1 is equal to or less than the reference value RV, there is illustrated an example in which the first transport speed is made slower and the second transport speed is made faster as the average value of the current values in the period a2 increases. In addition, in this case, there is illustrated an example in which both the first transport speed and the second transport speed are adjusted so that the speed difference after the first transport speed and the second transport speed are adjusted is equal to the speed difference after the second transport speed is adjusted in the exemplary embodiment.
In addition, in the case of adjusting the first transport speed, there is illustrated an example in which the transport speed of the recording medium P by the separation roller 66, the registration roller 68 and the like is a1 so adjusted to the adjusted first transport speed. In addition, in this case, there is further illustrated an example in which the transfer speed of a toner image to the intermediate transfer belt 42 by the image forming unit 16, the primary transfer unit 18, and the like is also adjusted.
In addition, the exemplary embodiment has been made with reference to the case where a determination as to whether or not a current value is the peak value is made by a comparison between the current value and a threshold value, but is not limited thereto. For example, a determination as to whether or riot a current value is the peak value may be made by a comparison between a value obtained by integrating the current values with a predetermined period, a moving average value of the current values, or the like and the threshold value.
In addition, the exemplary embodiment has been described with reference to the case where the speed-difference adjustment processing program is previously installed in the ROM 102 has been described, but is not limited thereto. For example, the speed-difference adjustment processing program may be in the form of being provided by being stored in a storage medium such as a compact disc read only memory (CD-ROM), or in the form of being provided via a network.
In addition, the exemplary embodiment has been described with reference to the case where the speed-difference adjustment processing is realized by a software configuration using a computer by executing a program has been described, but is not limited thereto. For example, the speed-difference adjustment processing may be realized by a hardware configuration, or the combination of a hardware configuration and a software configuration.
In addition, the configuration of the image forming apparatus 10 (see
In addition, the flow of a processing of the speed-difference adjustment processing program (see
The foregoing description of the exemplary embodiments of the invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-172250 | Sep 2016 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20050169683 | Tanaka | Aug 2005 | A1 |
| 20150153689 | Russel | Jun 2015 | A1 |
| 20170008715 | Morino | Jan 2017 | A1 |
| Number | Date | Country |
|---|---|---|
| 05-281874 | Oct 1993 | JP |
| 2003-285484 | Oct 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20180067426 A1 | Mar 2018 | US |
