JP2017223885A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of shortening a warming-up time, while satisfying a flicker regulation value.SOLUTION: An image forming device includes: a temperature control part 411 for controlling a fixing temperature of a fixing roller to a target temperature based on an array pattern including an on-state and an off-state with a half-wave period of an AC power supply 71 as a unit for each control frequency; a temperature calculation part 412 for obtaining a temperature difference between a fixing temperature and a target temperature for each temperature detection frequency shorter than the control frequency when the fixing temperature is controlled by the temperature control part 411; and a switching part 413 for switching the array pattern based on the temperature difference obtained by the temperature calculation part 412. The array pattern satisfies a flicker regulation value, and the switch part 413 switches a standard array pattern to a regulation array pattern based on the temperature difference before the next control frequency arrives.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus capable of realizing many functions such as a printer, a copier, and a facsimile is known. An electrophotographic image forming process, that is, a step of outputting image information by an electrophotographic method includes an image forming step and a fixing step. In the image forming process, an electrostatic latent image is written on a charged photoreceptor, toner is attached to the electrostatic latent image, and the toner is transferred to paper. In the fixing step, the toner transferred to the paper is welded by the fixing roller.

  In the fixing process, if the fixing temperature of the fixing roller deviates from the target temperature, the image quality is greatly affected. Therefore, it is preferable that the fixing temperature is controlled with high accuracy. The fixing temperature is detected by a temperature detector provided around the fixing roller. The fixing temperature detected by the temperature detector is used for PID control and the like. As a result, the lighting output value of the halogen lamp that heats the fixing roller is determined (see, for example, Patent Document 1).

  The halogen lamp that heats the fixing roller uses high power, and therefore preferably satisfies the flicker regulation value. In order to control the heating of the halogen lamp, there has been proposed one that switches an arrangement pattern between an on state and an off state (see, for example, Patent Documents 2 and 3).

JP 09-258601 A JP 2014-228668 A Japanese Patent Laying-Open No. 2015-219461

  However, the conventional technology as described in Patent Document 1 cannot start or resume printing when the fixing temperature is significantly deviated from the target temperature and does not fall within the fixing threshold. Therefore, the warm-up time is extended.

  Further, as in the prior art described in Patent Document 2, when fixing control is performed by switching an on-state or off-state array pattern that does not affect the flicker regulation value for each control cycle, the array pattern switching timing is: Since it is every control cycle, it takes much time for the fixing temperature to converge to the target temperature.

  When the array pattern is switched without waiting for the control cycle, the flicker regulation value may be affected depending on the combination of array patterns before and after the switching. For example, in the conventional technique described in Patent Document 3, since the flicker value increases as the array pattern control period becomes shorter, the array pattern control period is set longer than the time period that does not affect the flicker value.

  Therefore, the prior arts of Patent Documents 1 to 3 cannot reduce the warm-up time while satisfying the flicker regulation value.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of reducing the warm-up time while satisfying the flicker regulation value. .

  In order to achieve the above object, the image forming apparatus according to the present invention has a fixing temperature of a fixing roller based on an array pattern including an on state and an off state, with a half wave period of an AC power supply as a unit for each control period. When the fixing temperature is controlled by the temperature control unit that controls the temperature to a target temperature, the temperature difference between the fixing temperature and the target temperature is obtained for each temperature detection period shorter than the control period. A temperature calculation unit, and a switching unit that switches the arrangement pattern based on a temperature difference obtained by the temperature calculation unit, wherein the arrangement pattern satisfies a flicker regulation value and has a plurality of different duty ratios. Each of which is assigned and corresponds to a reference sequence pattern over the control period, and is related to the reference sequence pattern, And when the time required for the fixing temperature to converge to the target temperature is shortened, the switching unit corresponds to the temperature difference before the next control cycle arrives. Based on this, the reference array pattern is switched to the restriction array pattern.

  Further, in the image forming apparatus according to the present invention, a reference convergence time at which the fixing temperature converges to the target temperature at a duty ratio in the control cycle, and a duty ratio based on the temperature difference obtained by the temperature calculation unit. A time determination unit that determines a magnitude relationship with a reference convergence time at which the fixing temperature converges to the target temperature; and the switching unit determines that the reference convergence time is shorter than the reference convergence time by the time determination unit. In this case, it is preferable to switch the reference arrangement pattern to the restriction arrangement pattern.

  In the image forming apparatus according to the present invention, the array pattern further includes a case where the array pattern corresponds to a switch determination array pattern at a switch determination time, and the switching unit includes the switch determination array pattern included in the array pattern. Based on the above, it is preferable that the reference array pattern is switched to the restriction array pattern, and the switching determination time is shorter than the control period and longer than the temperature detection period.

  The image forming apparatus according to the present invention may further include a first detection unit that detects an ambient temperature of the fixing roller and a second detection unit that detects the fixing temperature, and the time determination unit includes the first detection unit. Obtaining the reference convergence time based on the ambient temperature detected by one detection unit, the fixing temperature detected by the second detection unit, and a change rate of the fixing temperature for each temperature detection period; It is preferable.

  In the image forming apparatus according to the present invention, the time determination unit obtains the reference convergence time based on a control coefficient corresponding to the temperature difference, and the control coefficient includes a proportional component, an integral component, or It is preferable that a differential component is included.

  In the image forming apparatus according to the aspect of the invention, it is preferable that the switching unit selects one of the plurality of different duty ratios that is closest to the duty ratio based on the temperature difference.

  In the image forming apparatus according to the aspect of the invention, it is preferable that the temperature control unit converges the fixing temperature within a fixable range between an upper limit temperature of the target temperature and a lower limit temperature of the target temperature. .

  In the image forming apparatus according to the present invention, when the switching unit determines that the reference arrangement pattern matches any of the restriction arrangement patterns at the changeover determination time, It is preferable to switch to a match.

  In the image forming apparatus according to the present invention, when the switching unit determines that a part of the reference arrangement pattern matches a part of the restriction arrangement pattern at the changeover determination time, It is preferable to switch to a part that matches.

  In the image forming apparatus according to the present invention, when the switching unit includes an odd number of patterns having three or more half-wave periods, and the odd number of patterns includes a pattern that continues even times, It is preferable to determine that it matches a part of the regulatory sequence pattern.

  Further, in the image forming apparatus according to the present invention, when the time determination unit does not determine that the reference arrangement pattern matches any of the restriction arrangement patterns, the reference convergence time for each temperature detection period, It is preferable to determine a magnitude relationship with the reference convergence time.

  Further, in the image forming apparatus according to the present invention, when the time determination unit does not determine that the reference array pattern coincides with a part of the restriction array pattern, the reference convergence time for each temperature detection period, It is preferable to determine a magnitude relationship with the reference convergence time.

  According to the present invention, the warm-up time can be shortened while satisfying the flicker regulation value.

1 is a diagram illustrating an example of an overall configuration of an image forming apparatus 1 according to Embodiment 1 of the present invention. FIG. 6 is a diagram illustrating a configuration example of a fixing unit 630 according to Embodiment 1 of the present invention. It is a figure which shows the function structural example of the control part 41 in Embodiment 1 of this invention. It is a figure which shows an example of the correlation with the arrangement | sequence pattern in Embodiment 1 of this invention, and a flicker regulation value. It is a figure which shows the example of a change of the fixing temperature in Embodiment 1 of this invention. It is a flowchart explaining the example of control in Embodiment 1 of this invention. It is a flowchart explaining the switchable determination process in Embodiment 1 of this invention. FIG. 10 is a diagram illustrating a configuration example of a fixing unit 630 according to a second embodiment of the present invention. It is a figure which shows an example of correlation with the arrangement | sequence pattern in Embodiment 2 of this invention, and a flicker regulation value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

Embodiment 1. FIG.
FIG. 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus 1 according to the first embodiment of the present invention. As shown in FIG. 1, an image forming apparatus 1 is an example of a color copying machine, acquires image information by reading a color image formed on a document T, and superimposes colors based on the acquired image information. A device for forming a color image. The image forming apparatus 1 is suitable for being applied to a color printer, a facsimile machine, or a complex machine thereof in addition to a color copying machine.

  The image forming apparatus 1 includes an image forming apparatus main body 11. A color image reading unit 12 and an automatic document feeder 14 are disposed on the upper part of the image forming apparatus main body 11. The image forming apparatus main body 11 includes a control unit 41, an image processing unit 43, an image forming unit 60, a paper feeding unit 20, and a conveyance unit 30, which will be described in detail later.

  The automatic document feeder 14 is provided on the image reading unit 12 and performs an operation of automatically feeding one or a plurality of documents T in the automatic feeding mode. The automatic paper feed mode is an operation of feeding a document T placed on the automatic document feeder 14 and reading an image printed on the document T.

  Specifically, the automatic document feeder 14 includes a document placement unit 141, a roller 142 a, a roller 142 b, a roller 143, a roller 144, a reversing unit 145, and a paper discharge tray 146. On the document placing portion 141, one or a plurality of documents T are placed. A roller 142 a and a roller 142 b are provided on the downstream side of the document placing portion 141. A roller 143 is provided on the downstream side of the rollers 142a and 142b. The automatic document feeder 14 includes a positioning detection unit 81 on the outer peripheral side of the roller 143.

  When the automatic paper feeding mode is selected, the document T fed out from the document placement unit 141 is rotated by a roller 143 and conveyed. When the document T is placed on the document placing unit 141 and the automatic paper feeding mode is selected, it is preferable that the recording surface of the document T is facing upward.

  When the document T is read by the image reading unit 12, the document T is conveyed by the roller 144 and discharged to the discharge tray 146. The automatic document feeder 14 can cause the image reading unit 12 to read not only the recording surface of the document T but also the back side of the recording surface of the document T by conveying the document T to the reversing unit 145.

  The positioning detection unit 81 detects the document T on which an image is printed. The positioning detection unit 81 is configured by, for example, a reflective photosensor. When the document T is detected, the positioning detection unit 81 rises an output signal. When the document T is no longer detected, the output signal falls, and the result is transmitted to the control unit 41.

  The image reading unit 12 reads a color image formed on the document T, that is, a color image printed on the document T. The image reading unit 12 includes a one-dimensional image sensor 128. In addition to the image sensor 128, the image reading unit 12 includes a first platen glass 121, a second platen glass 122, a light source 123, mirrors 124 to 126, an imaging optical unit 127, and an optical drive unit (not shown). Prepare.

  The light source 123 irradiates the document T with light. An optical drive unit (not shown) relatively moves the document T or the image sensor 128 in the sub-scanning direction. The sub-scanning direction is a direction orthogonal to the main scanning direction when the arrangement direction of the plurality of light receiving elements constituting the image sensor 128 is the main scanning direction.

  When the document T is conveyed by the automatic document feeder 14, an image on one side or both sides of the document T is scanned and exposed by the optical system of the image reading unit 12. The image sensor 128 reads the light including the reflected light of the incident light output during the image reading operation. In the Plato mode, the image sensor 128 outputs an RGB color system image reading signal Sout obtained by reading the document T. The platen mode is an operation of automatically reading an image printed on the document T placed on the first platen glass 121 by driving an optical drive unit (not shown).

  As the image sensor 128, a three-line color CCD imaging device is used. The image sensor 128 is configured by arranging a plurality of light receiving element arrays in the main scanning direction. Specifically, each of the red (R), green (G), and blue (B) light detection reading sensors divides pixels at different positions in the sub-scanning direction orthogonal to the main scanning direction. Then, the optical information of each of the R color, G color, and B color is read simultaneously. For example, in the automatic paper feeding mode and when the document T is reversed onto the U shape by the roller 143, the image sensor 128 reads the surface of the document T and outputs an image reading signal Sout.

  More specifically, the image sensor 128 performs photoelectric conversion of light and is connected to the image processing unit 43 via the control unit 41. The analog image reading signal Sout photoelectrically converted by the image sensor 128 is subjected to analog processing, A / D conversion, shading correction, image compression processing, scaling processing, and the like. The image read signal Sout subjected to various processes by the image processing unit 43 becomes digital image data including an R color component, a G color component, and a B color component. Based on the three-dimensional color information conversion table, the image processing unit 43 converts the image data, that is, RGB code, into Y (yellow), M (magenta), C (cyan), and K (black) color image data, that is, , Dy, Dm, Dc, Dk. The image processing unit 43 transfers the converted image data to the LED writing units 611Y, 611M, 611C, and 611K included in the image forming unit 60.

  The image forming unit 60 uses electrophotographic process technology and forms an intermediate transfer type color image. The image forming unit 60 employs a vertical tandem system. Specifically, the image forming unit 60 forms a color image based on the image data transferred from the image processing unit 43, that is, Dy, Dm, Dc, Dk. The image forming unit 60 includes image forming units 601Y, 601M, 601C, and 601K for each color, a transfer unit 620, and a fixing unit 630.

  The image forming unit 601Y forms a Y (yellow) color image. The image forming unit 601Y includes an image carrier 613Y, a charging unit 614Y, an LED writing unit 611Y, a developing unit 612Y, and a cleaning unit 616Y.

  The image carrier 613Y forms a Y-color toner image. The charging unit 614Y is disposed around the image carrier 613Y and uniformly charges the surface of the image carrier 613Y to a negative polarity by corona discharge. The LED writing unit 611Y irradiates the image carrier 613Y with light corresponding to the image of the Y color component. The developing unit 612Y visualizes the electrostatic latent image and forms a toner image by attaching toner of a Y color component to the surface of the image carrier 613Y. The cleaning unit 616Y removes transfer residual toner remaining on the surface of the image carrier 613Y after the primary transfer.

  Since each of the image forming units 601M, 601C, and 601K has the same configuration and function as the image forming unit 601Y except that the color of the image to be formed is different, the description thereof is omitted.

  The image forming units 601Y, 601M, 601C, and 601K are collectively referred to as an image forming unit 601. The LED writing units 611Y, 611M, 611C, and 611K are collectively referred to as the LED writing unit 611. The developing units 612Y, 612M, 612C, and 612K are collectively referred to as the developing unit 612. The image carriers 613Y, 613M, 613C, and 613K are collectively referred to as an image carrier 613. The charging units 614Y, 614M, 614C, and 614K are collectively referred to as a charging unit 614. The cleaning units 616Y, 616M, 616C, and 616K are collectively referred to as a cleaning unit 616.

  The transfer unit 620 includes a transfer medium 621, primary transfer rollers 622Y, 622M, 622C, and 622K, a secondary transfer roller 623, a belt cleaning device 624, and the like.

  The transfer medium 621 is composed of an endless belt, and is stretched in a loop shape by a plurality of support rollers 625. At least one of the plurality of support rollers 625 functions as a driving roller, and the other functions as a driven roller. For example, it is preferable that the support roller 625 disposed downstream of the K component primary transfer roller 622K in the belt traveling direction functions as a drive roller. By functioning as a driving roller, the transfer medium 621 travels at a constant speed in the arrow Z direction.

  The primary transfer rollers 622Y, 622M, 622C, and 622K are arranged on the inner peripheral surface side of the transfer medium 621 so as to face the image carrier 613 of each color component. The primary transfer rollers 622Y, 622M, 622C, and 622K are pressed against the image carriers 613Y, 613M, 613C, and 613K with the transfer medium 621 interposed therebetween. As a result, a primary transfer nip for transferring the toner image from the image carriers 613Y, 613M, 613C, and 613K to the transfer medium 621 is formed.

  The primary transfer rollers 622Y, 622M, 622C, and 622K are collectively referred to as the primary transfer roller 622.

  The secondary transfer roller 623 is disposed on the outer peripheral surface side of the transfer medium 621 so as to face one of the plurality of support rollers 625. A support roller 625 disposed to face the transfer medium 621 functions as a backup roller. The secondary transfer roller 623 is pressed against a support roller 625 that functions as a backup roller with the transfer medium 621 interposed therebetween, so that a secondary transfer nip for transferring a toner image from the transfer medium 621 to the paper P is formed. .

  When the transfer medium 621 passes through the primary transfer nip, the toner image on the image carrier 613 is primarily transferred to the transfer medium 621 in order. Specifically, a primary transfer bias is applied to the primary transfer roller 622, and an electric charge having a polarity opposite to that of the toner is applied to the back surface side of the transfer medium 621, that is, the side in contact with the primary transfer roller 622. It is electrostatically transferred to the transfer medium 621.

  When the paper P passes through the secondary transfer nip, the toner image on the transfer medium 621 is secondarily transferred to the paper P. Specifically, a secondary transfer bias is applied to the secondary transfer roller 623, and a charge having a polarity opposite to that of the toner is applied to the back side of the paper P, that is, the side in contact with the secondary transfer roller 623. The image is electrostatically transferred to the paper P. The sheet P on which the toner image is transferred is conveyed to the fixing unit 630.

  The belt cleaning device 624 includes a belt cleaning blade that slidably contacts the surface of the transfer medium 621. The belt cleaning device 624 removes transfer residual toner remaining on the surface of the transfer medium 621 after the secondary transfer.

  In the transfer unit 620, instead of the secondary transfer roller 623, a secondary transfer belt (not shown) is looped around a plurality of secondary support rollers including the secondary transfer roller 623, so-called. A belt-type secondary transfer unit may be employed.

  The fixing unit 630 includes a heating roller 631 and a pressure roller 632, and fixes the toner image transferred by the image forming unit 60 to the paper P. The fixing unit 630 forms a fixing nip between the heating roller 631 and the pressure roller 632.

  The fixing unit 630 fixes the transferred toner image on the paper P through the action of pressure by the pressure roller 632 and heat of the heating roller 631. An image is printed on the paper P fixed by the fixing unit 630. The paper P on which the image is printed is discharged to the outside of the apparatus, for example, the paper discharge tray 305 by the paper discharge roller 304. The heating roller 631 and the pressure roller 632 are collectively referred to as a fixing roller.

  The paper feed unit 20 includes a paper feed cassette 200, a feed roller 201, and the like. The paper feed cassette 200 stores paper P. The delivery roller 201 takes in the paper P stored in the paper feed cassette 200 and sends it out to the transport unit 30.

  The transport unit 30 includes a transport path 300 and transports the paper P along the transport path 300. The conveyance path 300 includes a paper feed roller 302A, conveyance rollers 302B, 302C, and 302D, a registration roller 303, and the like.

  The conveyance path 300 conveys the paper P fed from the paper feeding unit 20 to the image forming unit 60. When image formation is also performed on the back surface of the paper P, after the image formation is performed on the front surface of the paper P, the paper P is separated by the branching unit 306 by the circulation paper path 307A, the reverse conveyance path 307B, The paper is conveyed in the order of the paper feed conveyance path 307C.

  FIG. 2 is a diagram illustrating a configuration example of the fixing unit 630 according to the first embodiment of the present invention. In addition to the above description, the fixing unit 630 includes a fixing heater 633, a heating control unit 634, a first detection unit 83, and a second detection unit 84. The first detector 83 detects the ambient temperature of the fixing roller. The second detector 84 detects the fixing temperature. The fixing heater 633 is provided inside the heating roller 631 and heats the heating roller 631. The heating control unit 634 controls the on state and the off state of the fixing heater 633. The fixing heater 633 is operated by a voltage applied from the AC power supply 71.

  FIG. 3 is a diagram illustrating a functional configuration example of the control unit 41 according to the first embodiment of the present invention. The image forming apparatus 1 executes various processes via the control unit 41. For example, the image reading signal Sout output from the image reading unit 12 is transmitted to an image memory (not shown) or the image processing unit 43 via the control unit 41. The image memory is composed of, for example, a hard disk.

  Specifically, the control unit 41 is configured mainly with a CPU, a ROM, a RAM, and an I / O interface (not shown). In the control unit 41, the CPU reads out various programs corresponding to the processing contents from the ROM or the storage unit 42, expands them in the RAM, and controls the operations of the respective units of the image forming apparatus 1 in cooperation with the expanded various programs. .

  That is, the control unit 41 controls the operation of the image forming apparatus 1 and can be realized by a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface (not shown). Various functions including a temperature control unit 411, a temperature calculation unit 412, a switching unit 413, and a time determination unit 414 are realized by the control unit 41 executing a predetermined control program.

  The temperature control unit 411 controls the fixing temperature of the fixing roller to the target temperature based on the arrangement pattern including the on state and the off state, with the half wave cycle of the AC power supply 71 as a unit for each control cycle. When the fixing temperature is controlled by the temperature control unit 411, the temperature calculation unit 412 obtains a temperature difference between the fixing temperature and the target temperature for each temperature detection period shorter than the control period. The switching unit 413 switches the arrangement pattern based on the temperature difference obtained by the temperature calculation unit 412.

  FIG. 4 is a diagram illustrating an example of the association between the arrangement pattern and the flicker regulation value according to the first embodiment of the present invention. As shown in FIG. 4, the array pattern satisfies the flicker regulation value and is assigned with a plurality of different duty ratios, and corresponds to the reference array pattern over the control period, and the reference pattern And a case where the time when the fixing temperature converges to the target temperature is shortened and the case corresponds to the restriction arrangement pattern.

  The control period is 600 msec, for example. In FIG. 4, the shaded area corresponds to the on state, and the non-shaded area corresponds to the off state. The switching unit 413 switches the reference arrangement pattern to the restriction arrangement pattern based on the temperature difference obtained by the temperature calculation unit 412 before the next control cycle arrives.

  The time determination unit 414 refers to a reference convergence time at which the fixing temperature converges to the target temperature at the duty ratio in the control cycle, and a reference at which the fixing temperature converges to the target temperature at the duty ratio based on the temperature difference obtained by the temperature calculation unit 412. Determine the magnitude relationship with the convergence time. When the time determination unit 414 determines that the reference convergence time is shorter than the reference convergence time, the switching unit 413 switches the reference arrangement pattern to the restriction arrangement pattern.

  The array pattern includes a case corresponding to the switching determination array pattern at the switching determination time. The switching unit 413 switches the reference array pattern to the restriction array pattern based on the switching determination array pattern included in the array pattern. The switching determination time is shorter than the control cycle and longer than the temperature detection cycle.

  The time determination unit 414 is based on the ambient temperature detected by the first detection unit 83, the fixing temperature detected by the second detection unit 84, and the change rate of the fixing temperature for each temperature detection period. Ask for. The time determination unit 414 obtains a reference convergence time based on a control coefficient corresponding to the temperature difference, and the control coefficient includes a proportional component, an integral component, or a differential component.

  The switching unit 413 selects a plurality of different duty ratios that are closest to the duty ratio based on the temperature difference. The temperature control unit 411 converges the fixing temperature within a fixable range between the upper limit temperature of the target temperature and the lower limit temperature of the target temperature. FIG. 5 is a diagram illustrating a change example of the fixing temperature in the first embodiment of the present invention. As shown in FIG. 5, the fixing temperature is converged within the range of the target temperature ± k (° C.).

  When it is determined that the reference array pattern matches any of the restriction array patterns at the switching determination time, the switching unit 413 switches to one that matches any of the restriction array patterns.

  For example, as shown in FIG. 4, in the control cycle of 600 msec, the operation is to output a duty ratio of 60%, and the output of the array pattern is started. Thereafter, every 10 msec corresponding to the sampling period, the time to converge to the target fixing temperature and an appropriate duty ratio are calculated based on the ambient temperature, the fixing temperature, and the change rate of the fixing temperature. As a result of the calculation, it is determined whether or not the convergence time for convergence to the target fixing temperature is shortened. As described above, the target temperature ± k (° C.) is set within the fixable threshold.

  When the target temperature is changed, the time t1 when the fixing temperature falls within the fixable threshold value is obtained from the fixing temperature transition table when the reference arrangement pattern is executed under the conditions of the ambient temperature and the fixing temperature. Also, every 10 msec, the time t2 when the fixing temperature falls within the fixable threshold value is obtained from the fixing temperature transition table when the control coefficient is changed under the conditions of the ambient temperature and the fixing temperature. If time t1> time t2, the convergence time can be shortened.

  If the convergence time is not shortened, the time to converge to the target fixing temperature and an appropriate duty ratio are calculated again at the next sampling period, that is, at 20 msec, based on the ambient temperature, the fixing temperature, and the rate of change of the fixing temperature. To do. As a result of the calculation, it is determined whether or not the convergence time for convergence to the target fixing temperature is shortened. When the convergence time can be shortened, the duty ratio can be switched.

  Therefore, it is determined whether or not there is a switchable array pattern among the calculated duty ratios. If there is an array pattern that can be switched, switching is performed. If not, sampling is performed again at the next sampling period of 30 msec.

  If the duty ratio is changed to 50% after 70 msec and the convergence time is shortened, it is determined whether or not there is an array pattern that can be switched with an array pattern closest to the duty ratio of 50%. Arrangement pattern output at the time of determination at a duty ratio of 60% before switching (off, on, on, off, on, off, on) with a duty ratio of 60% in FIG. 4 and duty ratio after switching Compare 53% sequence patterns. Prior to switching, 1 to 7 with a duty ratio of 60% and 5 to 11 with a duty ratio of 53% after switching are the same arrangement pattern. That is, before and after switching, when it is determined that the arrangement pattern matches the arrangement pattern output before switching and that the arrangement pattern can be switched, the arrangement pattern is changed to an array pattern with a duty ratio of 53%.

  Further, it is assumed that 1 to 7 having a duty ratio of 60%, which is lit and output before switching, is output to 5 to 11 having a duty ratio of 53%. After switching, by turning on and outputting 15 waves from 12 to 15 in total, the duty ratio 60% can be changed to 53% while satisfying the flicker regulation value.

  In the above description, the seven arrangement patterns 1 to 7 having a duty ratio of 60% and the five arrangement patterns having a duty ratio of 53% and 5 to 11 completely coincide with each other. However, in the case of complete matching, if the control pattern is in the first half of the start of control, the probability that the switchable array pattern is completely matched is high, but in the latter half of control start, the probability of the complete matching of the array pattern is low. Therefore, there is a possibility that the arrangement pattern cannot be switched.

  Therefore, even if it is not completely coincident, for example, among the array patterns of 1 to 7 having a duty ratio of 60% before switching, a set number of consecutive array patterns are included in the array pattern having a duty ratio of 53% after switching. In this case, the arrangement pattern can be switched. The number before switching is preferably set to the minimum number 3 of array patterns that minimizes time.

  In short, when the switching unit 413 determines that a part of the reference array pattern matches a part of the restriction array pattern at the switching determination time, the switching unit 413 switches to a part that matches the part of the restriction array pattern. In addition, the switching unit 413 determines that the pattern matches with a part of the restriction array pattern when the pattern is an odd number of patterns having three or more half-wave periods and an odd number of patterns continues an even number of times. When it is not determined that the reference array pattern matches any of the restriction array patterns, the time determination unit 414 determines the magnitude relationship between the reference convergence time and the reference convergence time for each temperature detection period. When it is not determined that the reference array pattern matches a part of the restriction array pattern, the time determination unit 414 determines the magnitude relationship between the reference convergence time and the reference convergence time for each temperature detection period.

  Further, in the control cycle, the output of the array pattern is started by the calculation that outputs the duty ratio of 33%. After that, the sampling period was calculated at each timing of 10, 20, and 30 msec. In other words, the calculation was performed three times, but the switchable array that does not shorten the convergence time or satisfies the flicker regulation value in the past three calculations. There is no pattern.

  However, when it is determined that if the sampling period is 40 msec and the duty ratio is switched to 47%, it is determined that the convergence time will be shortened, and the arrangement pattern (1 of the duty ratio 33% is output at the time of determination with the duty ratio 33% before switching). 4) and the array pattern having a duty ratio of 47% to be switched are compared. If the array pattern matches the array pattern output before switching and can be switched, such as 5 to 8 of the duty ratio 47% after switching, the duty ratio is switched to 47%.

  By outputting 1 to 4 with a duty ratio of 33% output before switching and 5 to 8 with a duty ratio of 47%, a total of 15 waves from 9 to 15 with a duty ratio of 47% are output after switching. By doing so, the duty ratio 33% can be changed to 47% while satisfying the flicker regulation value.

  FIG. 6 is a flowchart for explaining a control example in the first embodiment of the present invention. In step S11, fixing control is started. In step S12, it is determined whether or not a control cycle has arrived. When it is determined that the control period has arrived, the process proceeds to step S13. On the other hand, if it is not determined that the control period has arrived, step S12 remains.

  In step S13, the fixing temperature and the ambient temperature are detected. In step S14, the duty ratio is determined. In step S15, it is determined whether or not a sampling period comes. If it is determined that the sampling period has arrived, the process proceeds to step S16. On the other hand, if it is not determined that the sampling period has arrived, step S15 remains.

  In step S16, the fixing temperature and the ambient temperature are detected. In step S17, the convergence time is calculated. In step S18, it is determined whether or not the convergence time is shortened. When it is determined that the convergence time is shortened, the process proceeds to step S19. On the other hand, if it is not determined that the convergence time is shortened, the process proceeds to step S22. In step S19, a switchable determination process is executed. Details of the processing will be described later.

  In step S20, it is determined whether there is a switchable array pattern. If it is determined that there is a switchable array pattern, the process proceeds to step S21. On the other hand, if it is not determined that there is a switchable array pattern, the process returns to step S15.

  In step S21, the array pattern is switched and the process ends. In step S22, it is determined whether or not the next control cycle comes. When it is determined that the next control week cycle is coming, the process returns to step S13. On the other hand, when it is not determined that the next control week cycle comes, the process returns to step S15.

  FIG. 7 is a flowchart illustrating the switchable determination process according to the first embodiment of the present invention. In step S41, the arrangement patterns before and after switching are compared. In step S42, it is determined whether or not all output array patterns are included in the array pattern after switching. When it is determined that all output array patterns are included in the array pattern after switching, the process proceeds to step S46. On the other hand, if it is not determined that all output array patterns are included in the array pattern after switching, the process proceeds to step S43.

  In step S43, it is determined whether or not a set number of consecutive array patterns immediately before switching are included in the array pattern after switching. If it is determined that a set number of array patterns that are immediately before switching are included in the array pattern after switching, the process proceeds to step S45. On the other hand, if it is not determined that the set number of array patterns that are immediately before switching are included in the array pattern after switching, the process proceeds to step S44.

  In step S44, it is determined that there is no switchable array pattern. In step S45, it is determined whether the flicker regulation value is satisfied even if the array pattern is switched. If it is determined that the flicker regulation value is satisfied even if the arrangement pattern is switched, the process proceeds to step S46. On the other hand, if it is not determined that the flicker regulation value is satisfied even if the array pattern is switched, the process returns to step S44.

  In step S46, it is determined that there is a switchable array pattern.

  From the above description, in the present embodiment, the arrangement pattern satisfies the flicker regulation value and is assigned with a plurality of different duty ratios, and corresponds to the reference arrangement pattern over the control period. And the case where it corresponds to the reference arrangement pattern when it is related to the reference arrangement pattern and the time for the fixing temperature to converge to the target temperature is shortened, and the next control cycle arrives Previously, the reference array pattern is switched to the restriction array pattern based on the temperature difference, so that the time required for convergence to the target temperature is shortened compared with the control pattern that is selected from the array patterns that satisfy the flicker restriction value. Can be selected and switched, so the warm-up time can be shortened while satisfying the flicker regulation value. .

  Further, in this embodiment, when it is determined that the reference convergence time based on the duty ratio based on the temperature difference between the fixing temperature and the target temperature is shorter than the reference convergence time based on the duty ratio at the control period, the reference array pattern By switching to the restriction arrangement pattern, the time for the fixing temperature to converge to the target temperature can be shortened, so that the warm-up time can be shortened as a whole.

  Furthermore, in the present embodiment, the reference array pattern is switched to the restriction array pattern based on the switching determination array pattern at the switching determination time, and the switching determination time is shorter than the control cycle and shorter than the temperature detection cycle. Since it can be switched from the middle of the reference array pattern without waiting for the next control cycle to arrive, the time for switching to another array pattern can be shortened.

  Further, in the present embodiment, the reference convergence time for the current control reference array pattern is accurately obtained by obtaining the reference convergence time based on the ambient temperature, the fixing temperature, and the change rate of the fixing temperature. Since it can obtain | require, the difference with the reference convergence time which is a comparison object can be clarified.

  Further, in this embodiment, the reference convergence time is obtained based on a control coefficient corresponding to the temperature difference between the fixing temperature and the target temperature, and the control coefficient includes a proportional component, an integral component, or a differential component. Thus, under the current environmental conditions such as the fixing temperature, it is possible to accurately obtain the time for the fixing temperature to converge to the target temperature by PID control. Can be determined.

  Further, in the present embodiment, among the plurality of different duty ratios, the one close to the duty ratio based on the temperature difference between the fixing temperature and the target temperature is selected, so the fixing temperature is targeted at a time close to the reference convergence time. Since the time for the temperature to converge can be converged, the warm-up time can be surely shortened as compared with the current control.

  Furthermore, in the present embodiment, the fixing temperature is converged within a fixing range between the upper limit temperature of the target temperature and the lower limit temperature of the target temperature, so that a range where the fixing temperature should be converged is expanded. The warm-up time can be further shortened.

  Further, in the present embodiment, when it is determined that the reference array pattern matches any of the restriction array patterns at the switching determination time, the flicker restriction is switched by matching with any of the restriction array patterns. Since arrangement patterns having different duty ratios are selected from the array patterns satisfying the values, it is possible to shorten the time for the fixing temperature to converge to the target temperature while reliably satisfying the flicker regulation value.

  Furthermore, in the present embodiment, when it is determined that a part of the reference sequence pattern matches a part of the restriction sequence pattern at the switching determination time, by switching to a part of the restriction sequence pattern. Since a part having a different duty ratio is selected from a part of the array pattern satisfying the flicker regulation value, the fixing temperature is converged to the target temperature while satisfying the flicker regulation value even if the array patterns do not completely match. Time can be shortened.

  Further, in the present embodiment, as a case where the pattern coincides with a part of the regulatory arrangement pattern, an odd number of patterns having three or more half-wave periods and a pattern in which the odd number of patterns are continued even times are included. Thus, since the current flowing through the circuit component such as the control element is not biased in the positive direction or the negative direction, the deterioration of the circuit component such as the control element can be prevented.

  Furthermore, in this embodiment, when it is not determined that the reference array pattern matches any of the restriction array patterns, the magnitude relationship between the reference convergence time and the reference convergence time is determined for each temperature detection period. Even if the timing does not match at the timing of the temperature detection cycle, the determination is performed again at the next temperature detection cycle, so that over the control cycle, an array pattern that can shorten the time to converge the fixing temperature to the target temperature is repeatedly searched. be able to.

  Furthermore, in this embodiment, when it is not determined that the reference array pattern matches a part of the restriction array pattern, the magnitude relationship between the reference convergence time and the reference convergence time is determined for each temperature detection period. Even if it does not coincide with a part of the timing of the temperature detection cycle, the determination is made again in the next temperature detection cycle, so the arrangement pattern that can shorten the time for the fixing temperature to converge to the target temperature over the control cycle Can be searched repeatedly.

Embodiment 2. FIG.
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the second embodiment, a fixing heater 1633 is provided in addition to the fixing heater 633.

  FIG. 8 is a diagram illustrating a configuration example of the fixing unit 630 according to the second embodiment of the present invention. As shown in FIG. 8, the fixing unit 630 further includes a fixing heater 1633 in addition to the fixing heater 633. Therefore, a first detection unit 183, a second detection unit 184, and a heating control unit 1634 are provided for the fixing heater 1633. Since each function is the same as that of the first embodiment, the description thereof is omitted.

  FIG. 9 is a diagram illustrating an example of association between the arrangement pattern and the flicker regulation value according to the second embodiment of the present invention. In FIG. 9 as well, in the same way as in the first embodiment, it is possible to search for an array pattern that shortens the convergence time while satisfying the flicker regulation value by complete match or partial match of the array pattern. Since the fixing heater 633 and the fixing heater 1633 are used, the duty ratio is up to 200%.

  As described above, the image forming apparatus 1 according to the present invention has been described based on the embodiment. However, the present invention is not limited thereto, and modifications may be made without departing from the spirit of the present invention.

  For example, in the present embodiment, various functions including the temperature control unit 411, the temperature calculation unit 412, the switching unit 413, and the time determination unit 414 have been described as examples of the functions implemented by the control unit 41. It is not limited. For example, each function may be realized by a wiring logic circuit or the like.

  In addition, an example in which the image reading signal Sout is determined by the RGB color system as digital image data (RGB code) including R color, G color, and B color components has been described. However, the present invention is not limited to this, and L * a * It may be determined by a different color system such as b * color system.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Image forming apparatus main body 12 Image reading part 121 1st platen glass 122 2nd platen glass 123 Light source 124-126 Mirror 127 Imaging optical part 128 Image sensor 14 Automatic document feeder 141 Original document mounting part 142a , 142b, 143, 144 Roller 145 Reversing unit 146 Discharging tray 20 Feeding unit 200 Feeding cassette 201 Feeding roller 30 Conveying unit 300 Conveying path 302A Feeding roller 302B, 302C, 302D Conveying roller 303 Registration roller 304 Discharging roller 305 Output tray 306 Branching unit 307A Circulating paper path 307B Reverse conveyance path 307C Refeed conveyance path 41 Control unit 411 Temperature control unit 412 Temperature calculation unit 413 Switching unit 414 Time determination unit 42 Storage unit 43 Image processing 60 Image forming unit 601, 601Y, 601M, 601C, 601K Image forming unit 611, 611Y, 611M, 611C, 611K LED writing unit 612, 612Y, 612M, 612C, 612K Developing unit 613, 613Y, 613M, 613C, 613K Image carrier Body 614, 614Y, 614M, 614C, 614K Charging unit 616, 616Y, 616M, 616C, 616K Cleaning unit 620 Transfer unit 621 Transfer medium 622, 622Y, 622M, 622C, 622K Primary transfer roller 623 Secondary transfer roller 624 Belt cleaning device 625 Support roller 630 Fixing part 631 Heating roller 632 Pressure roller 633, 1633 Fixing heater 634, 1634 Heating control part 71 AC power supply 81st Deciding detection unit 83,183 first detection portion 84, 184 second detection unit P paper T document

Claims (12)

A temperature control unit that controls the fixing temperature of the fixing roller to a target temperature based on an array pattern including an on state and an off state, with a half wave period of the AC power supply as a unit for each control cycle;
When the fixing temperature is controlled by the temperature control unit, a temperature calculation unit that obtains a temperature difference between the fixing temperature and the target temperature for each temperature detection cycle shorter than the control cycle;
Based on the temperature difference obtained by the temperature calculation unit, a switching unit for switching the arrangement pattern,
With
The arrangement pattern is:
It satisfies the flicker regulation value and is assigned a plurality of different duty ratios,
Corresponding to a reference array pattern over the control period;
Corresponding to the restriction arrangement pattern when there is a relationship with the reference arrangement pattern and the time for the fixing temperature to converge to the target temperature is shortened;
Including
The switching unit is
Before the next control cycle arrives, based on the temperature difference, switch the reference array pattern to the restriction array pattern,
Image forming apparatus. Reference convergence time at which the fixing temperature converges to the target temperature at the duty ratio at the control cycle, and a reference at which the fixing temperature converges to the target temperature at a duty ratio based on the temperature difference obtained by the temperature calculation unit It further includes a time determination unit that determines the magnitude relationship with the convergence time,
The switching unit is
When the time determination unit determines that the reference convergence time is shorter than the reference convergence time, the reference arrangement pattern is switched to the restriction arrangement pattern.
The image forming apparatus according to claim 1. The arrangement pattern is:
Further includes a case of corresponding to the switching determination arrangement pattern at the switching determination time,
The switching unit is
Based on the switching determination arrangement pattern included in the arrangement pattern, the reference arrangement pattern is switched to the restriction arrangement pattern,
The switching determination time is
Shorter than the control period and longer than the temperature detection period,
The image forming apparatus according to claim 2. A first detector for detecting the ambient temperature of the fixing roller;
A second detector for detecting the fixing temperature;
Further comprising
The time determination unit
Based on the ambient temperature detected by the first detector, the fixing temperature detected by the second detector, and the rate of change of the fixing temperature for each temperature detection period, the reference convergence time is calculated. Ask,
The image forming apparatus according to claim 3. The time determination unit
Based on a control coefficient corresponding to the temperature difference, the reference convergence time is obtained.
The control coefficient is
Contains proportional, integral, or derivative components,
The image forming apparatus according to claim 4. The switching unit is
Of the plurality of different duty ratios, the one closest to the duty ratio based on the temperature difference is selected.
The image forming apparatus according to claim 5. The temperature controller is
Converging the fixing temperature within a fixable range between the upper limit temperature of the target temperature and the lower limit temperature of the target temperature;
The image forming apparatus according to claim 6. The switching unit is
In the switching determination time, when it is determined that the reference arrangement pattern matches any of the restriction arrangement patterns, switching to one that matches any of the restriction arrangement patterns,
The image forming apparatus according to claim 7. The switching unit is
In the switching determination time, when it is determined that a part of the reference arrangement pattern matches a part of the restriction arrangement pattern, switching to a part of the restriction arrangement pattern is performed.
The image forming apparatus according to claim 7. The switching unit is
When the half-wave period is an odd number of patterns having three or more and the odd number of patterns includes an even number of consecutive patterns, it is determined that the pattern matches a part of the restriction array pattern.
The image forming apparatus according to claim 9. The time determination unit
If it is not determined that the reference array pattern matches any of the restriction array patterns, the relationship between the reference convergence time and the reference convergence time is determined for each temperature detection period.
The image forming apparatus according to claim 10. The time determination unit
If it is not determined that the reference array pattern matches a part of the restriction array pattern, the relationship between the reference convergence time and the reference convergence time is determined for each temperature detection period.
The image forming apparatus according to claim 11.

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