JP2004151141A - Fixing device and image forming apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device for securing excellent fixing by securing a more suitable job interval time without adhering to only just prior job. <P>SOLUTION: The fixing device has pairs of fixing rotators, provided with a heat source on at least one and fixing recording sheets of different size, and a control means for controlling an ahead-and-behind after job time interval by regarding operation sporadically or continuously fixing the recording the sheets as the job. The control means can control the time interval on the further prior job of the just prior job. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic method, such as a copying machine, a printer, a facsimile, and a multifunction peripheral thereof, and more particularly to control of a fixing timing of a fixing device of the image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, image forming apparatuses such as copiers and printers using an electrophotographic system and an electrostatic transfer system have been widely known. Such an image forming apparatus includes a pair of fixing rotators that rotate while being pressed against each other at a certain temperature, and a recording sheet holding a toner image is passed through a nip portion of the fixing rotator pair. A fixing device that heats and fixes a toner image on recording paper by the action of heat and pressure given by a rotating body pair is generally used.
[0003]
Further, when a job for fixing a relatively large size recording paper immediately follows a job for continuously fixing a large amount of recording papers of a relatively small size, the temperature distribution in the rotation axis direction of the fixing rotator is reduced. Due to the bias, the amount of heat applied to the large-size recording paper is partially different, which causes problems such as wrinkling of the large-size recording paper. To solve such a problem, for example, a technique disclosed in Patent Document 1 has been proposed.
[0004]
FIG. 7 schematically shows the technique disclosed in Patent Document 1. In this technique, the rest time between two jobs J (i) and J (i-1) is determined based on the size of the recording paper fixed in job J (i-1) immediately before job J (i) and the number of sheets. Alternatively, the idling time of the fixing roll is controlled.
[0005]
[Problems to be solved by the invention]
However, the technique disclosed in Patent Literature 1 is not sufficient because a problem such as wrinkling of a recording sheet may occur in the following cases. For example, in the job J (i-2), a small amount of recording paper is fixed in a large amount (for example, 500 sheets), and then in the job J (i-1), a small amount of the same small size recording paper (for example, one sheet). When the large-sized recording sheet is further fixed by the job J (i), the job J (i-1) and the job J (i) can be fixed without considering the job J (i-2). Since the rest time and the like are controlled, as shown in the lower graph in FIG. 7, the temperature distribution in the rotation axis direction of the fixing roll is biased (the temperature of the portion corresponding to the small-size recording paper is low, If the temperature of the other portion is high), a problem such as wrinkling may occur if a large-sized recording sheet is immediately fixed in this state.
[0006]
The present invention has been made in view of such a technical problem, and an object thereof is to secure a favorable fixing property by securing a more appropriate job interval time without being limited to only the immediately preceding job. It is an object of the present invention to provide a fixing device that can perform the fixing.
[0007]
[Means for Solving the Problems]
That is, the present invention provides a fixing rotator pair having a heat source on at least one side and capable of fixing recording sheets of different sizes, and a time interval between preceding and succeeding jobs as an operation of fixing a recording sheet sporadically or continuously as one job. , Which is a fixing device capable of controlling the time interval based on a job that is earlier (preceding) than a job immediately before a certain job. By configuring the fixing device in this manner, it is possible to secure a more appropriate job interval time and secure good fixing performance without being limited to only the immediately preceding job. Note that the size of the recording sheet fixed in one job (the length in the rotation axis direction of the fixing rotating body) is generally the same.
[0008]
Specifically, the control unit controls the time interval based on the size and / or the number of recording sheets to be fixed (in the rotation axis direction of the fixing rotating body). Further, the control means may determine that the size of the recording sheet to be fixed in a certain job (in the rotation axis direction of the fixing rotator) is larger than the size of the recording sheet to be fixed in the immediately preceding job (in the rotation axis direction of the fixing rotator). If it is larger, the time interval is (actively) controlled.
[0009]
More specifically, the control means includes a counter for counting the cumulative number of fixed recording sheets of a specific size (in the rotation axis direction of the fixing rotating body), and controls the time interval based on the cumulative number of fixing sheets. Things. The control means includes a plurality of counters for counting the cumulative number of fixed sheets of a plurality of types of recording sheets of a specific size (in the rotation axis direction of the fixing rotator), and a part or all of the plurality of cumulative fixed sheets. The time interval may be controlled based on
[0010]
The control unit does not reset the accumulated number of sheets between jobs when a recording sheet of a specific (same) size (in the rotation axis direction of the fixing rotator) is fixed in preceding and succeeding jobs. Regardless of only the immediately preceding job, a more appropriate job interval time is secured, and good fixing performance is secured.
[0011]
Further, the control means may include a timer for measuring an elapsed time from the end of the immediately preceding job, and may control the time interval based on the elapsed time. Further, the control unit may prohibit the fixing during the time interval, or may idle the fixing rotating body during the time interval.
[0012]
Further, the present invention can be considered as an image forming apparatus having these fixing devices.
[0013]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the image forming apparatus according to the present embodiment includes an image forming apparatus 10 that forms a toner image T based on image information and transfers the toner image T to a recording sheet P, The apparatus mainly includes a sheet feeding device 20 that is conveyed and supplied to the image forming unit 10 and a fixing device 30 that performs a fixing process on a recording sheet onto which a toner image has been transferred.
[0014]
The main part of the image forming apparatus 10 includes a photosensitive drum 11, a charging device 12, a laser exposure device 13, a developing device 14, a transfer device 15, a cleaner 16, and the like. Is formed.
[0015]
First, after the photosensitive drum 11 rotating in the direction of the arrow is uniformly charged by the charging device 12, a laser beam modulated based on image information is scanned and exposed from the laser exposure device 13 onto the charged drum 11. Thus, an electrostatic latent image is written. Subsequently, after the electrostatic latent image on the photosensitive drum 11 is developed by a toner (developer) supplied from the developing device 14 to be visualized as a toner image, the toner image is transferred to the photosensitive drum 11 and the transfer device. The image is transferred by the transfer device 15 to the recording sheet P supplied during the period 15. After the transfer, the surface of the photosensitive drum 11 is cleaned by the cleaner 16 to prepare for the next image forming process.
[0016]
The paper feeding device 20 includes a paper feeding tray 21 for stacking and storing a plurality of recording sheets P used for image formation, a feeding device 22 for feeding the stacked and stored recording sheets P one by one from the paper feeding tray 21, The main part thereof is constituted by a pair of registration rolls 23 for feeding the recording sheet P sent from the tray 21 between the photosensitive drum 11 and the transfer device 15 at a predetermined timing.
[0017]
In addition, in the entire image forming apparatus including the sheet feeding device 20, the conveyance of the recording sheet P is performed by adopting a side-register type conveyance system. For this reason, a feeding reference guide (not shown) having a feeding reference surface formed on the sheet storage surface is provided on the feeding tray 21 of the feeding device 20 in a protruding state. The position of one end of the recording sheet P to be accommodated is brought into contact with the conveyance reference surface of the conveyance reference guide so as to be aligned. The sheet feed tray 21 is provided with a sheet-side end regulating guide (not shown) slidable in a direction approaching or moving away from the transport reference guide at a position facing the reference surface of the transport reference guide.
[0018]
As shown in FIGS. 1 and 2, the fixing device 30 includes a heating roll (fixing rotating body) 31, and a pressure roll (fixing rotating body) 35 that presses against the heating roll 31 to form a fixing nip N. The main part is a roll nip type fixing device, and the fixing process is performed by introducing and passing the recording sheet P on which the toner image has been transferred by the image forming device 10 to the fixing nip portion. ing.
[0019]
The heating roll 31 includes a cylindrical roll base 32 made of a metal material or the like and a release layer 33 made of PFA or the like formed on the surface of the roll base 32, and is driven to rotate in the direction of the arrow. Are located in In addition, an electric heating lamp (heat source) 34 for heating the heating roll 31 is arranged in the internal space of the heating roll 31. On the other hand, the pressure roll 35 includes a cylindrical roll base 36 made of a metal material or the like, an elastic layer 37 formed on the surface of the base 36, and the like, and is pressed against the heating roll 31 at a predetermined pressure to be driven. It is arranged to rotate.
[0020]
A temperature sensor element 40 for detecting the surface temperature of the heating roll 31 is provided on the surface of the heating roll 31 so as to be in contact with the roll surface. The temperature sensor element 40 is connected to a control device 50 for controlling the overall operation of the fixing device 30, and transmits information on the detected surface temperature to the control device 50. The control device 50 is connected to a lamp drive control circuit 51 that performs on / off control of power supply to the electric heating lamp 34 and adjusts supply power, and is stored in a storage device or the like in advance of temperature information from the temperature sensor element 40. A control signal is transmitted to the lamp drive control circuit 51 in accordance with the fixing temperature control program. The control device 50 receives a start signal of an image forming operation and information signals on the type and number of recording sheets to be fed.
[0021]
Thus, in the fixing device 30, for example, when the main power supply of the image forming apparatus is turned on, power supply to the electric heating lamp 34 is started to heat the heating roll 31 to a predetermined fixing temperature. When the temperature detected by the temperature sensor element 40 exceeds a predetermined upper threshold (temperature), the power supply to the electric heating lamp 34 is stopped to stop the heating operation of the heating roll 31, while the heating roll 31 is stopped. When the temperature detected by the temperature sensor element 40 falls below a predetermined lower threshold value, the power supply to the electric heating lamp 34 is restarted and the heating operation of the heating roll 31 is restarted.
[0022]
Incidentally, as shown in FIG. 3, the control device (control means) 50 also controls the time interval between successive jobs. Here, the control device 50 includes a counter C for counting the cumulative number of fixed sheets of the recording sheet P of a specific size, and a timer T for measuring an elapsed time after the end of the job. In this embodiment, the time interval between the preceding and following jobs is the same as the idle time t during which the heating roll 31 and the pressure roll 35 idle.
[0023]
Hereinafter, an example of the operation of controlling the idling time t between jobs by the control device 50 will be described in detail as Embodiments 1 to 3.
[0024]
Example 1
FIG. 4 is a flowchart illustrating the operation of the idle rotation time t control between jobs of the fixing device 30 according to the first embodiment.
[0025]
First, a certain job J (i-2) starts (S100). The control device 50 determines whether the size of the recording sheet P to be fixed in the job J (i-2) is “small size (specific size)” (S101), and “small size (specific size)”. If not, the counter C starts printing (fixing) without counting the number of recording sheets P (S102), processes the job J (i-2), and ends printing (fixing). (S103).
[0026]
On the other hand, if the size of the recording sheet P to be fixed in this job J (i-2) is "small size (specific size)", printing (fixing) is started (S104), and the job J (i-2) is started. While processing 2), the counter C counts the number of the recording sheets P (S105), and ends printing (fixing) (S106). When the job J (i-2) ends, the timer T starts measuring the elapsed time after the job J (i-2) ends (S107). Note that the value of the counter C is not reset even when printing (fixing) is completed (S106).
[0027]
Then, when the next job J (i-1) starts (S108), the control device 50 sets in advance the measurement time (timer count number) by the timer T and the cumulative count number by the counter C up to that time. The value is multiplied by a constant A (S109). If the timer count is equal to or greater than the cumulative number of sheets × A, the values of both the counter C and the timer T are reset (S110), and the process proceeds to step S101. Transition.
[0028]
On the other hand, if the timer count is smaller than the cumulative number of sheets count × A, the control device 50 further determines that the size of the recording sheet P to be fixed in the job J (i-1) is “small size (specific size)”. It is determined whether or not it is (S111).
[0029]
If the size of the recording sheet P to be fixed in the job J (i-1) is "small size (specific size)", the control device 50 resets the value of the timer T (S112). Note that the value of the counter C is not reset. Then, printing (fixing) of the “small size” recording sheet P is started (S113), and the process proceeds to step S105. Thereafter, the next job J (i) starts without resetting the value of the counter C (S108).
[0030]
If the size of the recording sheet P to be fixed in the job J (i-1) is not "small size (specific size)", the heating roll 31 and the pressure roll 35 are idled for the idle time (specified time) t (S114). ). Here, the idling time (designated time) t is obtained by multiplying the accumulated count number of the counter C at that time by a preset constant B and further summing the preset constant C (S114).
[0031]
Then, the values of both the counter C and the timer T are reset (S115), printing (fixing) is started (S116), the job J (i-1) is processed, and printing (fixing) is ended (S117). ).
[0032]
Example 2
FIG. 5 is a flowchart illustrating the operation of the idle rotation time t control between jobs of the fixing device 30 according to the second embodiment. This embodiment is substantially the same as the first embodiment (for example, S200 corresponds to S100 of the first embodiment), and thus only different points from the first embodiment will be described.
[0033]
If the size of the recording sheet P to be fixed in the job J (i-1) is not "small size (specific size)", the heating roll 31 and the pressure roll 35 are idled for the idle time (specified time) t (S214). ). Here, the idling time (designated time) t is obtained by multiplying the accumulated count number of the counter C at that time by a preset constant B, and further summing the preset constant C, and further increasing the timer at that time. It is obtained by dividing the measurement time (timer count number) of T by a preset constant D (S214).
[0034]
Example 3
FIG. 6 is a flowchart illustrating the operation of the idle rotation time t control between jobs of the fixing device 30 according to the sixth embodiment. In this embodiment, the control device 50 includes a first counter C1 for counting the cumulative number of fixed sheets of A4 size (vertical feed) (first specific size) recording sheets, and a B4 size (second specific size) recording sheet. A second counter C2 for counting the cumulative number of P fixed sheets.
[0035]
First, a certain job J (i-2) starts (S300). The control device 50 determines whether or not the size of the recording sheet P to be fixed in the job J (i-2) is larger than “B4 size (second specific size)” (S301). If the number is larger than (one specific size), the counters C1 and C2 start printing (fixing) without counting the number of the recording sheets P (S302), and process the job J (i-2). Then, printing (fixing) ends (S303).
[0036]
Next, the control device 50 determines whether or not the size of the recording sheet P to be fixed in the job J (i-2) is larger than "A4 size (second specific size)" (S304). If the size is larger than the "size (second specific size)", the counter C1 starts printing (fixing) without counting the number of the recording sheets P (S302), and executes the job J (i-2). While processing, the counter C2 counts the number of the recording sheets P, and ends printing (fixing) (S309).
[0037]
On the other hand, when the size of the recording sheet P to be fixed in the job J (i-2) is equal to or smaller than “A4 size (second specific size)”, the counter C2 does not count the number of the recording sheets P. Then, printing (fixing) is started (S307), and while processing the job J (i-2), the counter C1 counts the number of the recording sheets P (S308), and ends printing (fixing) (S309). .
[0038]
When the job J (i-2) ends, the timer T starts measuring the elapsed time after the end of the job J (i-2) (S310). Note that the values of the first and second counters C1 and C2 are not reset even after printing (fixing) is completed (S309).
[0039]
When the next job J (i-1) starts (S311), the control device 50 determines the time measured by the timer T (timer count) and the first and second counters C1 and C2 up to that time. (S312), and when the timer count is equal to or greater than the cumulative number of sheets × A, the first and second counters C1, C2, all values of the timer T are reset (S313), and the process proceeds to step S301.
[0040]
On the other hand, if the timer count is smaller than the cumulative number of sheets count × A, the control device 50 further determines whether the size of the recording sheet P to be fixed in the job J (i-1) is equal to or smaller than the B4 size ( S314).
[0041]
If the size of the recording sheet P to be fixed in the job J (i-1) is larger than the “B4 size (second specific size)”, the heating roll 31 and the pressure roll 35 are rotated by the idle time (specified time) t. The idle rotation is performed (S315). Here, the idling time (designated time) t is obtained by multiplying the sum of the cumulative counts of the first counter C1 and the second counter C2 at that time by a preset constant B, and further summing the preset constant C. (S315). Then, all the values of the first and second counters C1, C2 and the timer T are reset (S316), printing (fixing) is started (S317), the job J (i-1) is processed, and printing ( (Fixing) ends (S318).
[0042]
If the size of the recording sheet P to be fixed in the job J (i-1) is equal to or smaller than "B4 size (second specific size)", the control device 50 further sets the recording sheet to be fixed in the job J (i-1). It is determined whether the size of P is equal to or smaller than “A4 size (first specific size)” (S319).
[0043]
When the size of the recording sheet P to be fixed in the job J (i-1) is larger than the “A4 size (first specific size)”, the heating roll 31 and the pressure roll 35 are moved for the idle time (specified time) t. The idle rotation is performed (S320). Here, the idling time (designated time) t is obtained by multiplying the accumulated count number of the first counter C1 at that time by a preset constant B and further summing the preset constant C (S320). ). Then, the values of both the first counter C1 and the timer T are reset (S321), printing (fixing) is started (S322), and the process proceeds to step S306. Note that the value of the second counter C2 is not reset, and is counted cumulatively in step S306.
[0044]
If the size of the recording sheet P to be fixed in the job J (i-1) is equal to or smaller than "A4 size (first specific size)", only the value of the timer T is reset (S323) and printing (fixing) is started. Then (S324), the process proceeds to step S308. The values of the first and second counters C1 and C2 are not reset, and the value of the first counter C1 is counted cumulatively in step S308.
[0045]
As described above, as shown in the first to third embodiments, the heating roll 31 and the pressure roll 35 are idled for an appropriate idle time (designated time) t between jobs (S114, S214, S321, S316). As shown by the thick arrow in the lower graph, the temperature distribution in the rotation axis direction of the heating roll 31 and the pressure roll 35 can be smoothed, and a good fixing property can be stably secured.
[0046]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a fixing device capable of securing a good fixing property by securing a more appropriate job interval time regardless of only the immediately preceding job. Can be.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment.
FIG. 2 is a schematic diagram of a fixing device according to the embodiment.
FIG. 3 is a conceptual diagram illustrating job interval control according to the present invention.
FIG. 4 is a flowchart illustrating a control procedure of an idle time according to the first embodiment;
FIG. 5 is a flowchart illustrating a control procedure of an idle time according to the second embodiment.
FIG. 6 is a flowchart illustrating a control procedure of an idling time according to a third embodiment.
FIG. 7 is a conceptual diagram illustrating conventional job interval control.
[Explanation of symbols]
31: heating roll (fixing rotating body), 35: pressure roll (fixing rotating body), 50: control device (control means)

Claims (10)

A fixing rotator pair including at least one heat source and capable of fixing recording sheets of different sizes, and a control unit for controlling a time interval between preceding and succeeding jobs, with an operation of fixing the recording sheets sporadically or continuously as one job. And a fixing device having
The fixing device is configured to control the time interval based on a job that precedes a job immediately before a certain job. The fixing device according to claim 1, wherein the control unit controls the time interval based on a size and / or the number of recording sheets to be fixed. The fixing device according to claim 1, wherein the control unit controls the time interval when a size of a recording sheet fixed in a certain job is larger than a size of a recording sheet fixed in a previous job. 4. The fixing device according to claim 1, wherein the control unit includes a counter that counts a cumulative number of fixed sheets of the recording sheet having a specific size, and controls the time interval based on the cumulative number of fixed sheets. 2. The control device according to claim 1, wherein the control unit includes a plurality of counters each counting a cumulative number of fixed sheets of a plurality of types of recording sheets of a specific size, and controls the time interval based on part or all of the plurality of cumulative fixed sheets. The fixing device according to any one of claims 1 to 4. When the recording sheet of a specific size is fixed in a preceding or succeeding job,
The fixing device according to claim 4, wherein the cumulative number of fixed sheets is not reset between jobs. The fixing device according to claim 1, wherein the control unit includes a timer that measures an elapsed time from the end of the immediately preceding job, and controls the time interval based on the elapsed time. The fixing device according to claim 1, wherein the control unit prohibits fixing during the time interval. The fixing device according to claim 1, wherein the control unit causes the fixing rotating body to idle during the time interval. An image forming apparatus comprising the fixing device according to claim 1.

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