JP4281295B2 - Image forming apparatus - Google Patents

Description

【００８３】
この結果、加熱ローラの設定温度の変更開始時期を電源スイッチ０Ｎ後６０分とし、加熱ローラの表面温度（温度設定値）はコピー待機時、ローパワーモード双方とも７℃の温度低下とした場合、定着装置の消費電力で１０ｗｈの削減が可能となった。
【００８４】
またここで、実際の画像形成装置への導入に当たっては、画像形成装置の大きさや各種バラつきを考慮し、加圧ローラの設定温度変更開始時期は電源スイッチＯＮ後３０〜９０分経過後とし、表面温度（温度設定値）の下げ幅を５〜１０℃とする。
【００８５】
図６において、電源スイッチのＯＮ後６０分経過時Ｄ以降の加圧ローラ表面の温度推移ｃを詳細に見ると、コピー待機モードＹ₁の時には上昇傾向にありローパワーモードＺ₁では若干低下の傾向にある。
【００８６】
ローパワーモードに切り替わった直後Ｆとその状態で放置された時点Ｇでは、切り替わった直後より放置された時点の方が加圧ローラの表面温度ｃが若干下がり、再度コピー待機モードへ戻すとき、加圧ローラの表面温度をローパワーモードに切り替わった直前の加圧ローラの表面温度に戻してやる必要がある。
【００８７】
図７において、ローパワーモードＺ₁の加熱ローラの温度制御の設定値ａをコピー待機モードＹ₁からローパワーモードへ移行直後には低く設定し、ローパワーモード移行後の経過時間に従って徐々に上げていく制御を行った。
【００８８】
ここで、ｂは加熱ローラ表面温度、ｃは加圧ローラ表面温度である。
但し、この制御は機械の電源がＯＮされウォーミングアップが完了してから十分に時間が経過し、加圧ローラ表面温度が飽和近くまで上昇した場合に可能であり、少なくとも機械電源ＯＮから８０分以上は経過している時にローパワーモードＺ₁に移行したことの条件が必要である。
【００８９】
定着状態がアンダー・オーバーにならない良好な定着状態を得るのに必要な、加熱ローラの温度設定値とローパワーモード移行後の経過時間との関係は、下表のとおりであった。
【００９０】
【表２】

【００９１】
この結果、機械電源ＯＮから８０分以上経過後のコピー待機モードからローパワーモードへの移行時の下げ幅を７℃とし、ローパワーモードの段階的上げ幅を１℃とした場合、ローパワーモードの消費電力として約２ｗｈの電力削減が可能となり、且つ安定した定着性能を得ることが可能となる。
【００９２】
またここで、実際の画像形成装置への導入に当たっては、画像形成装置の大きさや各種バラつきを考慮し、段階的設定変化の開始時期は電源スイッチＯＮ後７０分〜１００分経過以降とし、又その段階的設定温度の上昇幅は１〜３℃とする。
【００９３】
【発明の効果】
本発明によれば次のような効果を得ることが出来る、すなわち、
定着状態がアンダー、或いはオーバーになることもなく安定した定着が可能となり、且つ定着手段の消費電力の削減が可能となる。
【図面の簡単な説明】
【図１】本発明の実施の形態を示す画像形成装置の概略構成図である。
【図２】本発明の実施の形態を示す制御ブロック概略図である。
【図３】実施例に係る、定着装置の構成図である。
【図４】実施例に係る、加熱ローラの温度設定値の変化を説明する図である。
【図５】実施例に係る、加熱ローラの温度設定値の変化を示す図である。
【図６】実施例に係る、加熱ローラの温度設定値の変化を示す図である。
【図７】実施例に係る、加熱ローラの温度設定値の変化を示す図である。
【符号の説明】
６ 制御手段
４７ 定着手段
６３ タイマ
６４ 位相制御装置
６５ カウンタ
４７１ａ ハロゲンランプヒータ
４７３ 温度センサ
４７４ 加熱ローラ
４７５ 加圧ローラ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus having a heat roll type fixing device.
[0002]
[Prior art]
In a conventional heat roll type fixing device, the surface temperature of the heating roller is measured using a non-contact temperature sensor as a means of controlling the surface temperature of the heating roller in order to eliminate damage such as scratches on the coating layer on the surface of the heating roller. A means for controlling the surface temperature of the heating roller based on the measured value has been adopted.
[0003]
In this case, the actual temperature on the surface of the heating roller and the temperature measured by the temperature sensor that measures the surface temperature of the heating roller are generally lower than the measured temperature by ΔT ° C. Is set as the control target temperature, and the control target temperature is compared with the measured temperature of the temperature sensor so that the difference becomes zero (as a result, the heating roller surface temperature becomes the target temperature). The temperature of the heating roller surface has been controlled.
[0004]
[Problems to be solved by the invention]
In that case, the temperature of the surface of the heating roller and the temperature of the temperature sensor that measures the surface temperature of the heating roller are in addition to the temperature difference that occurs normally, and the temperature due to the first order lag when the surface temperature of the heating roller changes. A difference occurs.
[0005]
For this reason, at the time when the temperature of the fixing heater finally reaches the target value, such as immediately after the end of warming up, a first order lag occurs in the temperature of the temperature sensor itself with respect to the temperature of the heating roller, and the temperature difference ΔT described above. However, at this point of time, the fixing heater is normally controlled because the temperature difference ΔT ° C. is controlled as described above.
[0006]
However, as time elapses, the temperature of the temperature sensor itself increases and the temperature difference ΔT ° C. decreases, and as a result, the surface temperature of the heating roller tends to increase with respect to the target value as time elapses. As a result, there is a disadvantage that power consumption increases.
[0007]
The present invention has been made in view of such problems.
In other words, after the power switch of the image forming apparatus is turned on, it is possible to perform fixing without occurrence of abnormality at a relatively early time immediately after the completion of warming up and a time when sufficient time has elapsed, thereby reducing the power consumption of the fixing device. An image forming apparatus is provided.
[0008]
[Means for Solving the Problems]
Prior to explaining the means, the words are explained.
[0009]
Warming up refers to raising the temperature of the heating roller of the fixing unit of the image forming apparatus to a temperature at which fixing can be performed and setting various conditions related to image formation to enable copying. Warming up mode refers to warming up. Refers to the process to be performed.
[0010]
The copy standby mode refers to a process of waiting for a copy start instruction operation from the operator after the warm-up is completed.
[0011]
Also, the power saving mode (low power mode) means that, for example, the temperature (power consumption) of the heating roller is lowered to save power when there is no copy start instruction operation from the operator for a predetermined time or longer after entering the copy standby mode. Refers to a process.
[0012]
The inventor found that the energy required for fixing the toner is supplied from both the heating roller and the pressure roller in contact with the heating roller, and is the product of the contact portion temperature of both rollers and the time of nip between both rollers. As a result of studying the fixing state with respect to the heating roller temperature and the pressure roller temperature, it was recognized that not only the temperature of the heating roller but also the temperature of the pressure roller was important.
Pay attention to the fact that the pressure roller surface temperature rises with the passage of time after the power switch is turned on, and that the fixing can be normally performed even at a low temperature after the heating roller surface temperature has passed sufficiently after the warming up. Then, in the temperature control of the heating roller, the fixing temperature is changed by changing the set temperature of the heating roller according to the temperature (time) of the pressure roller, and the present invention has been achieved.
[0014]
  That is, the above object of the present invention is achieved by the following means.
  1.A fixing unit comprising: a heating roller heated by a heating element; a pressure roller that is in contact with the heating roller and disposed in parallel with the axial direction of the heating roller; and a control unit that controls the temperature of the heating roller. In the provided image forming apparatus,
It has a timer that starts time measurement when the power switch is turned on,
The control means switches from a copy standby mode that waits for a copy start instruction in a state in which the copy start operation is possible when the copy start operation is not performed for a predetermined time to a power saving mode that lowers the temperature of the heating roller for power saving. The timer is switched from power-onA second time determined separately from the predetermined timeAfter the predetermined time is measured, when the copy standby mode is shifted to the power saving mode, the measurement is performed after the power is turned on.SecondFrom the set temperature of the temperature control of the heating roller in the power saving mode before the predetermined time measurement,SecondThe temperature setting of the heating roller in the power saving mode after a predetermined time measurement is set to a low temperature, and the temperature control of the heating roller is performed based on each setting temperature of the temperature control of the heating roller.
Measured after the timer is turned onThe secondMeasured after turning on the power when shifting from the power saving mode to the copy standby mode after measuring for a predetermined timeThe secondMeasured after the power was turned on from the set temperature of the temperature control of the heating roller in the copy standby mode before measuring for a predetermined timeThe secondAn image forming apparatus characterized in that a set temperature of the temperature control of the heating roller in the copy standby mode after a predetermined time measurement is set low, and the temperature control of the heating roller is performed based on each set temperature of the temperature control of the heating roller. .
  2. The second predetermined time measured by the timer is 30 to 90 minutes after the image forming apparatus is turned on, and the set temperature difference of the temperature control of the heating roller before and after the second predetermined time measurement is 5 to 10 ° C. 2. The image forming apparatus as described in 1 above.
  3. The control means counts the number of transitions from the copy standby mode to the power saving mode after the second predetermined time measured after the timer is turned on, and the counter shifts from the copy standby mode to the power saving mode. The temperature control setting temperature of the heating roller in the power saving mode after counting the number of times of the transition of 2 times is set to the setting value of the temperature control of the heating roller in the power saving mode in the previous power saving mode. While setting the temperature control set value low,
The setting value of the temperature control of the heating roller is increased step by step with the passage of time after the transition to the power saving mode, compared to the setting value of the temperature control of the heating roller set low immediately after the transition to the power saving mode. 2. The image forming apparatus as described in 1 above, wherein
  4). The second predetermined time measured after the timer is turned on is 70 to 100 minutes, and the setting value of the temperature control of the heating roller is raised step by step as time elapses after the shift to the power saving mode. The heating roller temperature control set value increase range and the interval for increasing the set value are set to 1 to 3 ° C., and the interval for increasing the set value is extended with the passage of time after the shift to the power saving mode. 4. The image forming apparatus as described in 3 above.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
[0017]
First, an outline of the image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.
[0018]
In FIG. 1, reference numeral 1 denotes an image forming apparatus. A document is placed on a document feeding table 21 of an automatic document feeder 2 with an image surface facing upward. The image is read by the image reading means 3 in the process of being rotated counterclockwise integrally with the drum surface after being stopped once by 23 and adjusted to the leading end, and then a position that is substantially half a circle thereafter. 2 is branched from the drum surface and discharged to the paper discharge tray 25.
[0019]
In the image reading means 3, the first mirror unit 31 including the light source 311 and the mirror 312 sequentially reads and reads the passing document at a position directly below the transport drum 24 so as to be orthogonal to the moving direction of the document. The light is reflected by the second mirror unit 32 including the arranged mirror 321 and the mirror 322, and forms an image on the line-shaped image sensor 34 through the imaging lens 33.
[0020]
When the document is placed on the platen glass 35 and image information is read, it is reflected by the first mirror unit including the movable light source 351 and the first mirror 352 and the second mirror unit including the mirrors 353 and 354. Similarly, an image is formed on the line-shaped image sensor 34 via the imaging lens 33. The image reading unit 3 has been described above.
[0021]
The image information of the document read by the image reading unit 3 is subjected to image processing by the image processing unit 62 of the control unit 6, converted into a signal as image data, and temporarily stored in the storage unit 61.
[0022]
When the image formation is started, the image forming means 4 starts operating, the image data is called from the storage means 61 and inputted to the image writing means 43, and a laser beam projected according to the image data from a laser emitter (not shown) Scanning exposure in the axial direction of the photosensitive drum 41 and sub-scanning by the rotation of the photosensitive drum 41 are performed on the photosensitive drum 41 to which a potential has been previously applied by the charger 42 by the rotation operation of the polygon mirror (no symbol). Thus, an electrostatic latent image of the original image is formed on the photosensitive layer.
[0023]
The electrostatic latent image is reversely developed by the developing means 44 to become a toner image, and in parallel therewith, each paper feed of the manual paper feeding means 26 as the recording paper supply means or the paper feeding means 5 for storing the recording paper. One of the cassette feed rollers 52, 53, and 54 is actuated to carry the recording paper, fed to the transport rollers 55 and 56, and the timing roller 51, and in synchronization with the toner image on the photosensitive drum 41. Paper is fed to the body drum 41.
[0024]
The toner image on the photosensitive drum 41 is applied with a voltage of opposite polarity by the transfer unit 45 and transferred to the recording paper side to be transferred.
[0025]
The recording paper onto which the toner image has been transferred is neutralized by the static eliminator 46, separated from the photosensitive drum 41, and conveyed to the fixing unit 47 whose temperature is controlled by the control unit 6, and the heating roller 474, the pressure roller 475, and the like. The toner on the recording paper is melted and fixed by the pressure bonding and heating, and then discharged onto the tray 57.
[0026]
In the present embodiment, the fixing means 47 is a heating roller 474 having a heat-resistant release layer made of fluororesin on an aluminum base 471 in which a halogen lamp heater 471a, which is a heating element, is housed, and a heating roller in contact with the heating roller 471a. The pressure roller 475 has a heat-resistant elastic layer made of silicon rubber on an aluminum base disposed in parallel with the axial direction of the roller. A temperature sensor 473 for measuring the surface temperature of the heating roller 474 is attached approximately 0.7 mm away from the heating roller.
[0027]
On the other hand, the photosensitive drum 41 from which the recording paper has been separated is removed from the residual potential, and then the residual toner is removed and cleaned by the cleaning means 48, and the next image forming process is started.
[0028]
FIG. 2 is a control block schematic diagram showing an embodiment of the present invention.
First, the configuration will be described with reference to FIG.
[0029]
Reference numeral 1 denotes an image forming apparatus.
Reference numeral 90 denotes an AC power supply external to the image forming apparatus.
[0030]
Reference numeral 64 denotes a phase control device, which connects an AC power supply 90 to an AC input 643, connects a voltage command output 611 of the control means 6 to an output voltage setting input 641, and connects a halogen lamp heater 471 a to an AC output 642.
[0031]
Then, the phase control device 64 is connected to the AC voltage proportional to the temperature set value input to the output voltage setting input 641 (hereinafter, referred to as AC voltage proportional to the temperature set value). Is simply referred to as an AC output voltage).
[0032]
A temperature sensor 473 is connected to the temperature sensor input 612 of the control means 6.
The temperature sensor 473 is a thermistor or a thermocouple, measures the surface temperature of the heating roller 474, and inputs temperature information (temperature) of the heating roller to the temperature sensor input 612 of the control means 6.
[0033]
6 is a control means, which reads a temperature control program for the heating roller stored in advance in the storage means 61, and outputs a temperature setting value, which is a setting value for the temperature control of the heating roller, to the voltage command output 611 according to the control program. The temperature of the heating roller 474 is controlled via the control device 64.
[0034]
The control unit 6 includes a timer 63 that starts time measurement when a power switch (not shown) of the image forming apparatus 1 is turned on, and a counter 65 that counts the number of times of transition from the copy standby mode to the low power mode. ing.
[0035]
Reference numeral 62 denotes image processing means.
A halogen lamp heater 471a, which is a heating element, is built in the heating roller 474 of the fixing unit and heats the heating roller 474.
[0036]
Having described the configuration of the image forming apparatus, the control thereof will be described below with reference to FIGS.
[0037]
FIG. 4 is a diagram illustrating a change in the temperature setting value of the heating roller according to the embodiment.
FIG. 5 is a diagram illustrating a change in the temperature setting value of the heating roller according to the embodiment.
[0038]
FIG. 6 is a diagram illustrating a change in the temperature setting value of the heating roller according to the embodiment.
FIG. 7 is a diagram illustrating a change in the temperature setting value of the heating roller according to the embodiment.
[0039]
4-7,
The vertical axis indicates the temperature, and the horizontal axis indicates the elapsed time from the power switch ON.
[0040]
Point A on the horizontal axis indicates when the power switch is ON, point B indicates when warm-up is completed, point C indicates 10 minutes after completion, point D indicates completion 60 minutes, and point E indicates completion 90 minutes.
[0041]
In the graph, a (solid line) is the set value of the heating temperature of the heating roller, b (solid line) is the heating roller surface temperature, c (dashed line) is the pressure roller surface temperature, and d (broken line) is the heating roller surface by the temperature sensor. Indicates the measured temperature value. A to F added to a (solid line) in the graph are set values of the heating temperature of the heating roller, and A, C, and E are the first set temperature, the second set temperature, and the third set in the copy standby mode, respectively. B, D are the first set temperature and the second set temperature, respectively, and F is the stepped set temperature during the low power mode.
[0042]
X, Y, Z indicate the mode of the corresponding area, X part is the warm-up mode, Y, Y₁, Y₂Is copy standby mode, Z, Z₁The part shows the low power mode.
[0043]
The control in each mode will be described below.
▲ 1 ▼ Warming up mode
Hereinafter, a description will be given with reference to FIGS.
[0044]
When the operator turns on a power switch (not shown), the control means 6 determines that the warm-up mode X is in effect when the power switch is turned on.
[0045]
Then, the control means 6 obtains the first temperature setting value A in the copy standby mode, which is the set value of the temperature control of the heating roller in the warm-up mode and the copy standby mode, from the voltage command output 611 to the phase controller 64. The output is input to the output voltage setting input 641, and an AC output voltage proportional to the first set temperature in the copy standby mode is output from the AC output 642 of the phase controller 64 to start heating the halogen lamp heater 471 a.
[0046]
Here, the first temperature set value A in the copy standby mode is a set value for temperature control of the heating roller that can be copied in a state where no abnormality occurs. Further, only at the time of warming up, the first temperature set value may be set to 1.0 to 2 times, preferably 1.5 to 2 times that at the time of normal copying. In this case, the warming up time can be shortened. Here, if the magnification is too small, the heating time cannot be shortened, and if it is too large, the heater may be disconnected or cause deterioration.
[0047]
Then, the control means 6 compares the output from the temperature sensor 473 with the surface temperature (for example, approximately 200 ° C.) of the heating roller corresponding to the first temperature set value in the copy standby mode (hereinafter, the temperature in the copy mode). The surface temperature of the heating roller corresponding to the set value is referred to as a fixing temperature), and the surface temperature of the heating roller is controlled to be equal to the fixing temperature.
[0048]
Then, it is confirmed that the surface temperature of the heating roller has reached the fixing temperature, and at the same time, the warm-up mode X is completed when the preparatory operation for copying such as various conditions of the image forming process is completed.
[0049]
Then, the measurement time of the timer 63 when the warm-up mode is completed is set as a first predetermined time B.
[0050]
(2) Copy standby mode and copy mode
Hereinafter, a description will be given with reference to FIGS.
[0051]
When the warm-up mode X is completed, the control means 6 shifts the mode from the warm-up mode X to the copy standby mode Y.
[0052]
When the operation shifts to the copy standby mode Y, the operator can perform a copy start operation from an operation panel (not shown). When the copy start operation is performed, the control means 6 shifts the mode to the copy mode (not shown) by the copy start operation. Based on the image forming process stored in the storage unit 61, image forming control that is normally performed is performed. When the image forming process is completed, the process shifts to the copy standby mode Y again.
[0053]
In the copy standby mode Y, the control means 6 inputs the first temperature setting value A in the copy standby mode described above to the voltage command output 611 to the phase controller 64, and copies from the AC output 642 of the phase controller 64. An AC output voltage proportional to the first set temperature of the mode is output, and the output from the temperature sensor 473 is compared with the fixing temperature, so that the surface temperature of the heating roller becomes equal to the fixing temperature. The heating rate of the halogen lamp heater 471a is controlled by changing the energization rate of the AC voltage of the AC output 642, and a start instruction operation by the next operator is awaited.
[0054]
And, instead of “decreasing the setting value of the temperature control of the heating roller in accordance with the rise in the surface temperature of the heating roller”, “utilizing that the temperature of the heating roller increases with the passage of time after the power switch is turned on, In order to lower the set value of the temperature control of the heating roller in accordance with the elapse of time after the power switch is turned on, the control means 6 monitors the timer 63, and when a predetermined time elapses after the power switch is turned on (for example, 30). After 90 minutes, preferably 60 minutes) (for example, point D on the horizontal axis), when the mode shifts from the low power mode (for example, D) to the copy standby mode (for example, E), copy standby before the point in time when a predetermined time has elapsed. The setting value for the temperature control of the heating roller in the mode (for example, C) is set lower (the lowering range is 5 to 10 ° C., preferably 7 ° C.) (for example, C). ) And,
In the transferred copy standby mode, the temperature control of the heating roller is performed by the above-described method based on this lower set temperature (for example, E).
[0055]
Here, if the set value is lowered too low, the toner cannot be sufficiently melted, and unless it is changed, the power cannot be reduced.
[0056]
When a predetermined time elapses after the power switch is turned on (for example, 30 to 90 minutes, preferably 60 minutes), and after the copy standby mode is changed from the low power mode described later, that is, from the low power mode Z Copy standby mode Y₁When the process shifts to, the temperature setting value of the heating roller is updated from the first setting temperature A in the copy standby mode to the second set temperature C in the copy standby mode in which the setting value is lower. Then again low power mode Z₁Then the copy standby mode Y again₂Then, the temperature is updated to the third temperature set value E in the copy standby mode that is lower than the second set temperature value C in the copy standby mode. Thereafter, the update of the set temperature of the heating roller is repeated by the method described above until the temperature of the pressure roller substantially matches the temperature of the heating roller.
[0057]
(3) Low power mode
This will be described with reference to FIGS.
[0058]
If the copy activation operation by the operator is not performed for a predetermined time (for example, 15 minutes), the control unit 6 shifts the mode from the copy standby mode Y to the low power mode Z for energy saving.
[0059]
In order to save power in the low power mode, the control means 6 performs temperature control of the heating roller in the low power mode, which is lower than the first temperature set value A that has already been set in the warm-up mode or the copy standby mode. The first temperature setting value B in the low power mode, which is the setting value, is input from the voltage command output 611 to the output voltage setting input 641 of the phase control device 64 and from the AC output 642 of the phase control device 64 to the low power mode. An AC output voltage proportional to the first temperature set value B of
The surface temperature of the heating roller corresponding to the output from the temperature sensor 473 and the second temperature setting value (for example, 100 ° C.) (hereinafter, the surface temperature of the heating roller corresponding to the temperature setting value in the low power mode is referred to as the low power temperature) And the heating rate of the halogen lamp heater 471a is controlled by changing the AC voltage energization rate of the AC output 642 of the phase controller 64 so that the surface temperature of the heating roller becomes equal to the low power temperature, and the heating roller 474 is controlled. Is controlled to a low power temperature.
[0060]
When a predetermined time elapses after the power switch is turned on (for example, 30 to 90 minutes, preferably 60 minutes) and when the copy standby mode is shifted to the low power mode, that is, the copy standby mode Y₁To low power mode Z₁Then, the temperature is updated to the second temperature setting value D in the low power mode which is lower than the first temperature setting value B in the low power mode. Thereafter, the update of the set temperature of the heating roller is repeated by the method described above until the temperature of the pressure roller substantially matches the temperature of the heating roller.
[0061]
Here, the control means 6 monitors the timer 63, and the mode changes from the copy standby mode to the low power mode after a predetermined time (for example, 30 to 90 minutes, preferably 60 minutes) after the power switch is turned on. , The setting value of the temperature control of the heating roller is lower than the setting value of the temperature control of the heating roller in the low power mode before the predetermined time has passed (the range of decrease is 5 to 10 ° C., preferably 7). In the low power mode that is set and shifted, the temperature control of the heating roller is performed by the above-described method based on the lower set temperature.
[0062]
Here, if the set value is lowered too low, it takes too much time until reheating, the toner cannot be sufficiently melted, and the power cannot be reduced unless it is changed.
[0063]
Furthermore, the control means 6 monitors the value of the counter 65 for counting the number of times of transition from the copy standby mode to the low power mode and the timer 63 described above,
The counter 65 counts the number of times of transition from the copy standby mode to the low power mode after a predetermined time has elapsed since the power switch was turned on (for example, 30 to 90 minutes, preferably 60 minutes). The temperature control temperature setting of the heating roller in the low power mode after counting the number of times of transition from the mode to the low power mode twice is compared to the previous setting value of the temperature control of the heating roller in the low power mode. A set value of the temperature control of the heating roller in the power mode is set low (the range of decrease is 5 to 10 ° C., preferably 7 ° C.), and the temperature control of the heating roller is performed based on each setting temperature of the temperature control of the heating roller.
[0064]
Here, if the set value is lowered too low, it takes too much time until reheating, the toner cannot be sufficiently melted, and the power cannot be reduced unless it is changed.
[0065]
Furthermore, the control means 6 monitors the value of the counter 65 that counts the number of transitions from the copy standby mode to the low power mode, and the timer 63,
The counter 65 counts the number of times of transition from the copy standby mode to the low power mode after a predetermined time has elapsed since the power switch was turned on (for example, 70 to 100 minutes, preferably 80 minutes). The temperature control setting temperature of the heating roller in the low power mode that has shifted from the copy standby mode to the low power mode after the first time is compared to the setting value of the temperature control of the heating roller in the previous low power mode. The heating roller temperature control set value is set low (the range of decrease is 5 to 10 ° C., preferably 7 ° C.), and the temperature control of the heating roller is performed by the method described above based on the set value.
[0066]
Further, the control means 6 heats the heating roller temperature control set value set lower than the previous low power mode immediately after the transition to the low power mode according to the elapse of time after the transition to the low power mode. Set the temperature control setting value of the roller to be increased stepwise (the range of increase is 1 to 3 ° C.), and update the setting until the surface temperature of the pressure roller returns to the temperature just before the transition to the low power mode. The temperature control of the heating roller is performed by the method described above based on each set temperature that has been raised.
[0067]
As described above, according to the present invention, the setting value of the temperature control of the heating roller is set to be higher than that in the case of controlling the temperature of the heating roller while keeping the setting value of the temperature control of the heating roller at the setting value at the time of warming up. Since the control is performed to lower the power, the power consumption of the halogen lamp heater can be reduced without lowering the fixing performance.
[0068]
As described above, in order to “decrease the setting value of the temperature control of the heating roller in accordance with the temperature of the pressure roller”, the time elapsed from turning on the power switch using the fact that the temperature rise of the pressure roller increases with time. The means for lowering the set value of the temperature control of the heating roller by “
As a means for “lowering the setting value of the temperature control of the heating roller in accordance with the temperature of the pressure roller”, which is different from that means, the above-mentioned “setting value of the temperature control of the heating roller in accordance with the passage of time since the power switch is turned on” Instead of the “means for lowering the pressure”, a temperature sensor for measuring the surface temperature of the pressure roller is provided in the vicinity of the pressure roller, and according to the measured value of the surface temperature of the pressure roller by the sensor (for example, FIG. 5). It is also possible to control by the control means so as to lower the set value of the temperature control of the heating roller.
[0069]
Although the outline of the image forming apparatus of the present invention has been described above, since the test was performed, the embodiment will be described in detail below.
[0070]
<Example>
FIG. 3 is a configuration diagram of the fixing device according to the embodiment.
[0071]
In FIG. 3, reference numeral 47 denotes fixing means for fixing the image formed by the powder toner on the transfer paper P by passing the transfer paper P between two pairs of a heating roller 474 and a pressure roller 475. .
[0072]
As a configuration condition this time, the heating roller 474 has a diameter: 50 mm, a coating thickness of the surface layer: 20 μm, a core metal thickness: 9 mm (aluminum), a total length: 350 mm,
The pressure roller 475 has a diameter of 50 mm, a tube thickness of the surface layer: 70 μm, and an elastic layer thickness of 5 mm.
The heater is a 900 W halogen lamp heater 471a disposed in the center of the heating roller,
A temperature sensor 473 is installed at a position about 0.7 mm away from the surface of the heating roller, and the measured value of the surface temperature of the heating roller of the temperature sensor is compared with the target surface temperature of the heating roller to determine the heating roller surface temperature. An image forming apparatus using a fixing device that controls the temperature so as to be 190 ° C. is taken as an example.
[0073]
The two roller pairs are composed of a heating roller 474 on the upper side and a pressure roller 475 on the lower side. A halogen lamp heater 471a is arranged as a heater at the center of the heating roller core, and the temperature sensor 473 of the heating roller is a surface of the heating roller. They are arranged slightly apart (for example, 0.7 mm).
[0074]
Under this machine configuration condition, if the set value of the temperature control of the heating roller is a constant value immediately after the machine power is turned on and the temperature control of the heating roller is performed, when a sufficient time has passed, the heating roller, the pressure roller, and the fixing device Since the temperature of itself and the surrounding atmosphere increases, there is a margin in fixing performance.
[0075]
As shown in FIG. 4, the setting value a of the heating roller temperature control is lowered from A to B or D, the temperature of the heating roller is lowered, the excessive consumption of power is prevented, and the fixing abnormality does not occur. There is a control method.
[0076]
The reason why it is possible to obtain a predetermined fixing property even if the set value of the temperature control of the heating roller is lowered is that the surface of the pressure roller as the time elapses until the heater power is supplied to the fixing device and the copy standby state Y is reached. Looking at the transition of temperature c, even when the pressure roller itself does not have a heating means, the pressure roller surface temperature c gradually rises due to heat conduction from the heating roller, and 10 minutes after the completion of warming up C At 60 minutes elapsed time D, the total heat energy of the heating roller and the pressure roller is greatly different.
[0077]
For this reason, for example, the surface temperature of the heating roller at which the toner image on the transfer paper can be fixed is different between the time point C after 10 minutes and the time point D after 60 minutes, and when the warm-up is almost completed after a long time has elapsed. Fixing is possible at a lower heating roller surface temperature.
[0078]
Similarly, regarding the set temperature of the temperature control of the heating roller in the low power mode, the fixing can be performed at the time when the heating roller surface temperature is lower than when the warm-up is completed after a long time has passed.
[0079]
At 10 minutes and 60 minutes after the completion of warming up, if the low power mode is shifted to the copy standby mode at the same time (for example, 30 seconds), the target temperature reached by the heating roller is lower than that at the time of warming up. In addition to the lower power mode, the total heat energy of the heating roller and the pressure roller is greatly different. It becomes possible to set the temperature low, and the temperature setting value of the heating roller in the low power mode is shifted low according to the elapsed time from the completion of warming up, which can contribute to the reduction of power consumption.
[0080]
The same applies to the case where the copy standby mode is temporarily shifted to the low power mode and then the copy standby mode is again transferred.
[0081]
The relationship between the heating roller surface temperature (set temperature) and the elapsed time after power-on in each mode necessary for obtaining a good fixing state in which the fixing state does not become under / over is as shown in the table below.
[0082]
[Table 1]

[0083]
As a result, the heating roller set temperature change start timing is 60 minutes after the power switch 0N, and the heating roller surface temperature (temperature set value) is 7 ° C. in both the low power mode and the standby state for copying. A reduction in power consumption of the fixing device of 10 wh is possible.
[0084]
In addition, here, when introducing into an actual image forming apparatus, considering the size of the image forming apparatus and various variations, the set temperature change start time of the pressure roller is 30 to 90 minutes after the power switch is turned on. The range of decrease in temperature (temperature set value) is 5 to 10 ° C.
[0085]
In FIG. 6, when the temperature transition c on the surface of the pressure roller after D after 60 minutes has elapsed since the power switch is turned on, the copy standby mode Y₁At the time of the low power mode Z₁However, it is on a downward trend.
[0086]
At F immediately after switching to the low power mode and at time G when left in that state, the surface temperature c of the pressure roller is slightly lower than when switching to low power mode, and when returning to the copy standby mode again, It is necessary to return the surface temperature of the pressure roller to the surface temperature of the pressure roller immediately before switching to the low power mode.
[0087]
In FIG. 7, the low power mode Z₁Set the temperature control value a of the heating roller to copy standby mode Y₁Was set immediately after shifting from low power mode to low power mode and gradually increased according to the elapsed time after shifting to low power mode.
[0088]
Here, b is the heating roller surface temperature, and c is the pressure roller surface temperature.
However, this control is possible when sufficient time has elapsed after the machine power is turned on and the warm-up is completed, and the pressure roller surface temperature rises to near saturation, at least 80 minutes after the machine power is turned on. Low power mode Z when elapsed₁The condition of having moved to is necessary.
[0089]
The relationship between the temperature setting value of the heating roller and the elapsed time after shifting to the low power mode necessary for obtaining a good fixing state in which the fixing state does not become under-over is as shown in the table below.
[0090]
[Table 2]

[0091]
As a result, when the reduction width when shifting from the copy standby mode to the low power mode after 80 minutes has passed since the machine power is turned on is 7 ° C. and the stepwise increase width of the low power mode is 1 ° C., the low power mode The power consumption can be reduced by about 2wh, and stable fixing performance can be obtained.
[0092]
In addition, here, when introducing into an actual image forming apparatus, taking into account the size of the image forming apparatus and various variations, the start time of the stepwise setting change is 70 minutes to 100 minutes after the power switch is turned on. The increment of the stepped set temperature is 1 to 3 ° C.
[0093]
【The invention's effect】
According to the present invention, the following effects can be obtained:
Stable fixing can be performed without causing the fixing state to be under or over, and the power consumption of the fixing unit can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.
FIG. 2 is a control block schematic diagram showing an embodiment of the present invention.
FIG. 3 is a configuration diagram of a fixing device according to an embodiment.
FIG. 4 is a diagram illustrating a change in a temperature setting value of a heating roller according to an embodiment.
FIG. 5 is a diagram illustrating a change in temperature setting value of the heating roller according to the embodiment.
FIG. 6 is a diagram illustrating a change in temperature setting value of the heating roller according to the embodiment.
FIG. 7 is a diagram illustrating a change in temperature setting value of the heating roller according to the embodiment.
[Explanation of symbols]
6 Control means
47 Fixing means
63 timer
64 Phase control device
65 counter
471a Halogen lamp heater
473 Temperature sensor
474 Heating roller
475 Pressure roller

Claims (4)

A fixing unit comprising: a heating roller heated by a heating element; a pressure roller that is in contact with the heating roller and disposed in parallel with the axial direction of the heating roller; and a control unit that controls the temperature of the heating roller. In the provided image forming apparatus,
It has a timer that starts time measurement when the power switch is turned on,
The control means switches from a copy standby mode that waits for a copy start instruction in a state in which the copy start operation is possible when the copy start operation is not performed for a predetermined time to a power saving mode that lowers the temperature of the heating roller for power saving. After the power is turned on, when the timer shifts from the copy standby mode to the power saving mode after measuring a second predetermined time set apart from the predetermined time from power-on. than the set temperature of the temperature control of the heating roller in the measured said second predetermined time before measurement the power saving mode, lower the set temperature of the temperature control of the heating roller in the second power saving mode after a predetermined time measurement Set and perform temperature control of the heating roller based on each set temperature of the temperature control of the heating roller,
When the timer shifts from the power saving mode to the copy standby mode after the second predetermined time measured after the power is turned on, the copy standby mode before the second predetermined time is measured after the power is turned on. The set temperature of the heating roller temperature control in the copy standby mode after the second predetermined time measured after the power is turned on is set lower than the set temperature of the heating roller temperature control. An image forming apparatus that controls the temperature of the heating roller based on a set temperature. The second predetermined time measured by the timer is 30 to 90 minutes after the image forming apparatus is turned on, and the set temperature difference of the temperature control of the heating roller before and after the second predetermined time measurement is 5 to 10 ° C. The image forming apparatus according to claim 1. The control means counts the number of transitions from the copy standby mode to the power saving mode after the second predetermined time measured after the timer is turned on, and the counter shifts from the copy standby mode to the power saving mode. The temperature control setting temperature of the heating roller in the power saving mode after counting the number of times of the transition of 2 times is set to the setting value of the temperature control of the heating roller in the power saving mode in the previous power saving mode. While setting the temperature control set value low,
The setting value of the temperature control of the heating roller is increased step by step with the passage of time after the transition to the power saving mode, compared to the setting value of the temperature control of the heating roller set low immediately after the transition to the power saving mode. The image forming apparatus according to claim 1, wherein: The second predetermined time measured after the timer is turned on is 70 to 100 minutes, and the setting value of the temperature control of the heating roller is raised step by step as time elapses after the shift to the power saving mode. The heating roller temperature control set value increase range and the interval for increasing the set value are set to 1 to 3 ° C., and the interval for increasing the set value is extended with the passage of time after the shift to the power saving mode. The image forming apparatus according to claim 3.

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