JPH10268700A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that can shorten the wait time after toner replenishment while decreasing the power consumption,. SOLUTION: When toner absence is detected by a toner-absence detection sensor 36, a CPU 32 controls a fixing unit 10 according to a program, stored in a ROM 33, so as to lower the temperature of it. That, it is controls the temperature of the fixing unit 10 so that the degree of the temperature lowering of the fixing unit 10 is small compared to the case when heat control over the fixing heater 16 of the fixing unit 10 is stopped. In response to the output of a sensor 37 which reacts the opening/closing of a toner-replenishment door, the CPU 32 resumes ordinary temperature-control over the fixing unit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile apparatus for forming an image using an electrostatic image forming process, and more particularly to an image forming apparatus for fixing a heated image.

[0002]

2. Description of the Related Art A conventional image forming apparatus has a fixing device for fixing a heated image. The fixing device includes a heat roller heated by a fixing heater. The heat roller fixes the heated image on the sheet on which the toner image formed by the electrostatic image forming process is transferred. So that the heat roller maintains a predetermined temperature,
On / off control of the fixing heater is performed. In this specification, this temperature control is referred to as temperature control.

[0003]

By the way, toner is
Usually, it is supplied from a toner cartridge or the like. The amount of toner in the toner cartridge decreases as the image forming operation is performed, and finally, the toner cartridge is in a toner-free state. Conventionally, a sensor for detecting the presence or absence of toner is provided in a toner cartridge or the like in order to detect the absence of toner. When the absence of toner is detected, it is necessary to supply toner or replace the toner cartridge. In such a state without toner, the image forming operation becomes impossible, and if the temperature control is continued to maintain the fixing state, power consumption (energy) will be wasted. That is being done.

However, replenishment of the toner requires some time. Therefore, it takes a considerable amount of time (in some cases, about the same time as normal power-on) until the fixing temperature reaches a specified temperature after the temperature control is resumed after toner replenishment. Meanwhile, the user had to wait.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of reducing a power consumption of a fixing device and a waiting time after toner replenishment.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an image forming apparatus provided with a fixing device for heating and fixing a toner image on a sheet of paper. And control means for controlling the temperature lowering of the fixing device so that the degree of temperature decrease of the fixing device becomes slower than when the heating control of the fixing device is stopped. I do.

As described above, the control for lowering the temperature of the fixing unit is performed instead of immediately stopping the heating control of the fixing unit after the detection of the absence of toner, so that the fixing temperature returns to the original temperature after replenishing the toner. The time required can be reduced.
At the same time, since the fixing temperature is lowered, power consumption can be gradually reduced. This is in consideration of a balance between two conflicting requirements, that is, a reduction in recovery time from interruption of the image forming operation due to toner supply and a reduction in power consumption of the fixing device after the absence of toner. That is, in the early period after the absence of toner, priority is given to the request for shortening the return time, and the earlier the toner supply is, the shorter the time required for the return is. Conversely, at a later time after toner detection, priority is given to a request for power consumption reduction. That is, if it takes a long time to replenish the toner, even if it takes a long time to recover the toner, the power consumption can be reduced.

[0008] The control means operates, for example, to maintain the current temperature for a predetermined time in a plurality of stages while the temperature of the fixing device is decreasing in the lowering temperature control. Or you may control so that temperature may fall continuously.

To determine the timing of returning to the original temperature control state after the lowering temperature control, the following configuration can be considered.

That is, the control means includes means for detecting toner replenishment, and when the toner replenishment is detected during the period in which the temperature lowering control is being performed, the control means stops the temperature lowering control. Restart temperature control. of course,
The user may instruct the timing by operating an operation button or the like.

In order to perform the temperature lowering control, the power of the apparatus must be turned on. However, the user may turn off the power of the apparatus when supplying toner. To cope with this, the following configuration is conceivable.

That is, when the power-off instruction of the apparatus is detected during the period in which the temperature lowering control is being performed, the control means turns off the power after continuing the temperature lowering control to a predetermined time. . As a result, the predetermined falling temperature control can be performed even after the power is turned off by the user.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an embodiment of an image forming apparatus to which the present invention is applied. FIG. 1 mainly shows a configuration of a fixing control device which is a part of an image forming apparatus related to the present invention. The fixing control device includes a fixing device 10 for fixing a developed toner image to a sheet, a sheet discharging roller 20 for discharging the sheet after fixing, a toner non-detection sensor 36 for detecting that the toner has run out, and a toner non-detection sensor. The control unit 30 controls the fixing unit 10 according to the output of the sensor 36 and the temperature of the fixing unit 10, a toner supply door opening / closing sensor 37 for detecting opening of a toner supply door, and a power switch 39. The toner replenishment door open / close sensor 37 is a means for detecting that toner replenishment has been performed (or performed), and any other means can be used as long as the purpose can be achieved. The power supply circuit is not shown.

The fixing device 10 includes a heat roller 18 having a built-in fixing heater 16, a pressure roller 12 for pressing a sheet in opposition to the heat roller 18, and a plurality of heat rollers 18 installed in the longitudinal direction of the heat roller 18. It has a thermistor 14 which is a means for detecting a temperature.

The control unit 30 converts the analog output signal of the thermistor 14 into a digital signal corresponding to the analog output signal.
A D converter 31, a CPU 32 as control means, a ROM 33 as a non-volatile storage means storing control programs executed by the CPU 32 and necessary data, C
The heater driver 34 controls the fixing heater 16 under the control of the PU 32.

In the apparatus shown in FIG. 1, a change in the temperature of the heat roller 18 is detected by the thermistor 14 as a change in the voltage value, and is taken in as detection data by the CPU 32 via the A / D converter 31. Further, the CPU 32 includes a toner non-detection sensor 36 and a toner supply door opening / closing sensor 37.
And the ON / OFF of the power switch 39 are also monitored. The CPU 32 performs switching control (on / off control) of the fixing heater 16 via the heater driver 34 according to a control program stored in the ROM 33 so that the temperature of the fixing device 10 becomes a predetermined set temperature. A specific operation example of the CPU 32 will be described later.

In this specification, the "fixing temperature" indicates the surface temperature of the heat roller 18, and the reference fixing temperature (also referred to simply as the reference temperature) is TA0, and the current fixing temperature is TA.

Hereinafter, the operation of the image forming apparatus relating to the fixing temperature control in the present embodiment will be described.

FIG. 3 is a flowchart showing a process when the power of the image forming apparatus is turned on. This process is started when the power is turned on. In this process, the process of the main routine described below is started (S30).

FIG. 2 is a flowchart showing an example of the processing procedure of the main routine.

First, an initialization process is performed (S20). In this initialization process, in addition to the normal initialization process (for a copying machine, setting of default values such as the number of copies, paper size, magnification, etc.), setting of a reference temperature TA0 of a fixing device described later, and the like are also performed. Do.

Next, by checking the temperature detected by the thermistor 14, it is determined whether or not the fixing operation is possible (S21). If it is determined that the fixing operation is possible, the image forming operation is permitted (S22). After the image forming operation is performed (S23), the presence or absence of toner is checked (S24).
If no toner is detected, the image forming operation is stopped (S2).
5) A message or the like urging toner supply is displayed on the operation panel or the like to request the user to supply toner (S26).
At the same time, the power supply to the fixing heater is stopped, the normal fixing temperature control is stopped (S27), and the toner non-fixing temperature control described later is performed (S28). If there is toner, the process returns to step S21 to prepare for the next image forming operation.

FIG. 4 shows an example of an interrupt processing procedure of the CPU 32 which is started based on a signal from the toner supply door opening / closing sensor 37 when the toner supply door is opened / closed.

First, toner non-fixing temperature control (S2 in FIG. 2)
8, FIG. 6) is stopped (S40), and then the normal fixing temperature control (FIG. 5) is started (S41). Thereafter, the main routine (FIG. 2) is started (S42). As a result, the state returns to the normal temperature control state. As will be described in detail later, unless the time from the detection of the absence of toner to the replenishment of the toner is not so long, the decrease in the fixing temperature is suppressed, and the time required to return to the state in which the image forming operation can be performed is reduced. You. Further, in the present embodiment, the normal temperature control is restarted by opening and closing the toner supply door, but may be restarted after the supplied toner is detected by the toner non-detection sensor. However, in this case, the time until the return is slightly longer.

FIG. 5 shows an example of the processing procedure of the normal fixing temperature control. This process is periodically (for example, every several hundred milliseconds) executed by the CPU 32 using a well-known interval timer function of the CPU 32.

In the process of FIG. 5, first, the thermistor 1
By reading the output of No. 4, the current fixing temperature TA is detected (S50). Next, the current fixing temperature TA
Is compared with a predetermined reference fixing temperature TA0 (S51). If the current temperature TA is lower, the fixing heater 16 is turned on via the heater driver 34 (S5).
2). Conversely, if the reference temperature TA0 is lower, the fixing heater 16 is turned off via the heater driver 34 (S5).
3). Since the process of FIG. 5 is started periodically, the fixing heater 16 is controlled to be turned on and off so as to maintain the fixing temperature at the reference temperature TA0.

FIG. 6 is a flowchart showing an example of the processing procedure of the toner non-fixing temperature control S28 in the main routine of FIG.

In the process of FIG. 6, first, the current temperature control level L is reset to 0 (S60). Here, the temperature control level means a target temperature level in the temperature lowering control after no toner is detected, and in this embodiment, three levels (temperature control levels 1, 2, and 3) are prepared. I have. The target temperatures TA1, TA2, and TA3 of the temperature control levels 1, 2, and 3 are lower in this order than the reference temperature TA0. In the present embodiment, the difference between the adjacent temperatures of TA0, TA1, TA2, and TA3 is assumed to be about 10 ° C. However, the present invention is not limited to this.

Next, the current temperature control level L is incremented (S61). Thereby, the target temperature is lowered by one level. Next, it is checked whether or not the value of the temperature control level L has exceeded the value of the last temperature control level Llast (level 3 in this example) (S62). If not, the current temperature TA
Is compared with a predetermined target temperature TA (L) at the temperature adjustment level L (S64). If the current temperature TA is higher, the fixing heater 16 is turned off (S65), and the fixing heater 16 is kept off until the current temperature TA becomes lower than the target temperature TA (L). Current temperature TA is the target temperature T
A (L) or less, the current temperature T for a predetermined time Δt (L) according to the current temperature control level L
On / off control of the fixing heater 16 is performed so as to maintain A (S66, S67). The reason why the current temperature is maintained for the predetermined time in this way is to prevent the fixing temperature from suddenly lowering due to the fixing heater being turned off. Δt (L) is, for example, on the order of several minutes. After the elapse of the time Δt (L), the process returns to step 61, where the current temperature adjustment level L is further incremented, and the process waits until the fixing temperature falls to the new target temperature (S64, S65), and reaches the new target temperature. When the temperature drops, the target temperature is maintained for a predetermined time Δt (L) according to the temperature control level L (S66, S6).
7). Thereafter, the flow returns to step S61 again, and L becomes Llast
Is exceeded (Yes in S62), the fixing heater is turned off to allow the fixing temperature to drop to the ambient temperature (S62).
63). Instead of step S63, the current temperature TAlast is maintained until the power of the image forming apparatus is turned off by the user.
May be maintained. Alternatively, after maintaining the current temperature TAlast for a predetermined time, the power of the image forming apparatus may be automatically turned off without turning off only the fixing heater.

FIG. 7 is a graph showing a change in the fixing temperature TA after the absence of toner, which is obtained by the toner non-fixing temperature control of FIG. As can be seen from the figure, the fixing temperature TA
Is initially at the level of the reference temperature TA0 by the normal fixing temperature control (FIG. 5), but after detecting no toner, the temperature drops to the target temperature TA1 of the temperature control level 1 because the fixing heater is turned off. Thereafter, by controlling the fixing heater, the temperature TA1 is maintained for the time Δt (1). Then
When the fixing heater is turned off, the fixing temperature decreases to the target temperature TA2 of the temperature control level 2. Thereafter, by controlling the fixing heater, the temperature TA2 is maintained for the time Δt (2). Next, when the fixing heater is turned off, the fixing temperature decreases to the target temperature TA3 of the temperature control level 3. Thereafter, by controlling the fixing heater, the temperature TA3 is maintained for the time Δt (3). Thereafter, the fixing heater is turned off to allow the fixing temperature to drop to the ambient temperature. Here, as described above, it is possible to realize a modification such as maintaining the temperature TA3 of the last temperature adjustment level until the power of the apparatus is turned off (only the fixing heater is not turned off).

FIG. 8 is a graph showing a change in the fixing temperature TA after the resumption of the temperature control. In this embodiment, as described above, the temperature control is restarted by detecting the opening / closing of the toner supply door. As can be seen from the figure, the time required to reach the reference temperature TA0 differs depending on the temperatures TA1, TA2, and TA3 at the time when the temperature control is restarted. That is, if starting from the temperature TA1, the temperature reaches the reference temperature TA0 at the time t1, and the temperature TA1.
Starting from temperature 2, the reference temperature TA0 is reached at time t2, and starting from temperature TA3, the temperature reaches reference temperature TA0 at time t3. At time t4, when the fixing heater is turned off when no toner is detected, the time when the temperature reaches the reference temperature TA0 from the restart of the temperature control is shown. The time difference between the time point t4 and each of the time points t1, t2, t3 is Δt1, Δt2, Δt3, respectively.

As described above, according to the present embodiment, even if a certain amount of time is required for toner replenishment, the fixing temperature TA can be reduced to the reference temperature in a relatively short time unless the time is long. It is guaranteed to return to TA0. In addition, by controlling the temperature control level in a plurality of stages, the earlier the toner replenishment is performed after the absence of toner, the more quickly the toner temperature can be returned to the reference temperature TA0, and the longer the time, the longer the time elapses. Power consumption can be reduced.

In the present embodiment, the time Δt (1), Δt (2), Δt for maintaining the temperature at each temperature control level.
Although (3) is almost the same, it may be changed according to the temperature control level L. For example, Δt (1), Δt (2),
It is conceivable to increase the length in the order of Δt (3). this is,
Normally, when the fixing heater is turned off, the fixing temperature is set to the reference temperature TA0.
This takes into account that when the temperature decreases from the temperature to the ambient temperature, the rate of decrease is greater at the beginning of the decrease.

Next, another embodiment of the present invention will be described. The above embodiment has been described on the assumption that the power of the image forming apparatus is not turned off (cut off) by the user after the detection of no toner. However, when replenishing the toner, the user may turn off the power of the image forming apparatus. In this case, the above-described toner non-fixing temperature control does not work. Therefore, in the present embodiment, it is assumed that the power of the apparatus is turned off by software control by the CPU 32, and even if the user turns off the power after the detection of no toner, the final temperature control level of the toner non-fixing temperature control is set. The power is not turned off until the temperature holding time ends. Since the software control itself for turning off the power is known by a personal computer or the like, it will not be described in detail here.

FIG. 9 shows an example of a specific power-off processing procedure. This process is started when the user gives an instruction to turn off the power by operating the power switch 39.

In the process of FIG. 9, first, it is checked whether or not the toner non-fixing temperature control is currently being executed (S9).
0). If it is not being executed, the apparatus power is turned off as it is (S93). If it is being executed, it is checked whether the user has given an instruction to turn on the power again (S91). If there is, the process is terminated; otherwise, this state is continued until the end of the temperature holding time (Δt (3) in FIG. 7) of the last temperature control level (S
92). When the temperature holding time ends, the power is turned off (S93).

According to this embodiment, even when the user turns off the apparatus and replenishes the toner after detecting no toner, a large decrease in the fixing temperature is avoided, and it is possible to return to the reference fixing temperature in a short time. It becomes possible.

Next, still another embodiment of the present invention will be described.

In this embodiment, the current environmental temperature TR inside the apparatus is detected, and the time Δt (1), Δt for maintaining the temperature at each temperature control level according to this environmental temperature TR.
(2), Δt (3) is changed. this is,
It is to be considered that when the environmental temperature is high, the fixing temperature decreases slowly, whereas when the environmental temperature is low, the fixing temperature decreases steeply. For this purpose, a sensor (not shown) for detecting the environmental temperature TR is provided in the image forming apparatus.

Further, a time table 110 as shown in FIG. 11 is provided. The time table 110 includes a temperature range to which the current environmental temperature TR belongs and a temperature holding time Δt.
(1), values of Δt (2), Δt (3) “m33” to “m”
11 "is predetermined.
Is stored within. Although shown here in the form of a table,
This table information can be held in any form. For example, it can be incorporated in the program as a numerical value included in the description of the condition and the result in the program.

FIG. 10 shows an example of the processing procedure of the toner non-fixing temperature control in this embodiment.

The process of FIG. 10 is performed in step S6 of FIG.
6 and step S67, a new step S100
Is added. In this step S100, Δt (L) corresponding to the current environmental temperature TR is determined based on a predetermined time table 110 as shown in FIG.

According to this embodiment, the intended purpose can be achieved irrespective of the environmental temperature TR.

The preferred embodiment of the present invention has been described above, but various modifications are possible. For example, the temperature drop control is performed in three steps, but in one step, two steps,
Alternatively, four or more stages may be used. Further, the temperature may be continuously controlled to decrease.

[0046]

According to the image forming apparatus of the present invention, the waiting time after toner replenishment can be reduced while reducing power consumption. In other words, when toner is replenished in a relatively short time after toner is not detected, it is possible to reduce the waiting time until the image forming operation is restored after toner replenishment. Power consumption can be minimized.

[0047]

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a schematic configuration of an image forming apparatus to which the present invention is applied.

FIG. 2 is a flowchart illustrating a main routine process according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a process executed when power is turned on in the embodiment of the present invention.

FIG. 4 is a flowchart illustrating processing executed when opening and closing the toner supply door according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a processing procedure of normal fixing temperature control according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating a processing procedure of toner non-fixing temperature control according to an embodiment of the present invention.

FIG. 7 is a graph showing a change in a fixing temperature after no toner detection according to the embodiment of the present invention.

FIG. 8 is a graph showing a change in the fixing temperature after resuming the temperature control according to the embodiment of the present invention.

FIG. 9 is a flowchart showing a processing procedure executed when the power is turned off according to another embodiment of the present invention.

FIG. 10 is a flowchart showing a processing procedure of toner non-fixing temperature control according to still another embodiment of the present invention.

11 is an explanatory diagram of a time table used in the embodiment of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Fixing device, 12 ... Pressure roller, 14 ... Thermistor (temperature detecting element), 16 ... Fixing heater, 18 ... Heat roller, 20 ... Discharge roller, 31 ... A / D converter, 3
2 ... CPU (control means), 33 ... ROM, 34 ... heater driver, 36 ... toner non-detection sensor, 37 ... toner supply door opening / closing sensor, 39 ... power switch.

Claims (4)

[Claims] An image forming apparatus comprising a fixing device for heating and fixing a toner image on a sheet, a toner detecting means for detecting the presence or absence of toner, and a fixing device for detecting absence of toner by the toner detecting means. An image forming apparatus comprising: a control unit that controls a temperature lowering of the fixing unit so that the degree of temperature decrease of the fixing unit becomes slower than when the heating control is stopped. 2. The method according to claim 1, wherein the control means operates to maintain the current temperature for a predetermined time in a plurality of stages while the temperature of the fixing device is decreasing in the lowering temperature control. The image forming apparatus according to claim 1. 3. A controller for detecting toner replenishment, wherein the controller stops the lowering temperature control when the toner replenishment is detected during the period of performing the lowering temperature control. 3. The image forming apparatus according to claim 1, wherein the temperature control is restarted. 4. The apparatus according to claim 1, wherein when the power-off instruction of the apparatus is detected during the period in which the temperature lowering control is being performed,
4. The image forming apparatus according to claim 1, wherein the power supply is turned off after the temperature control is continued until a predetermined time.