JP6787302B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus including a fixing device for fixing a toner image on paper.

Image forming devices such as copiers, printers, fax machines, and multifunction devices are provided with a fixing device for fixing a toner image on paper. The fixing device has a fixing roller heated by a heat source and a pressure roller forming a pressure region for sandwiching and transporting the paper between the fixing rollers, and the paper is transported through the pressure region. , The toner image is heated and pressurized and fixed on the paper.

During the warm-up of the fixing device, the fixing rollers are heated by a heat source until the target temperature is reached. Since the target temperature is fixed, the presence or absence of overshoot and the overshoot temperature vary depending on the operating environment of the fixing device and the aged deterioration of each member. When an overshoot occurs, there are problems that the time until the temperature of the fixing roller stabilizes becomes long and the power consumption of the heat source increases.

Patent Document 1 describes a temperature control method in which a voltage change of a heat source is estimated from a temperature gradient of a fuser (fixing roller) at the time of warm-up, and an overshoot is predicted according to the voltage change. Patent Document 2 describes a fixing device that turns on and off the heating means (heat source) so as to reach a target temperature based on the temperature gradient of the fixing member at the time of warming up.

Japanese Unexamined Patent Publication No. 5-333944 JP-A-2002-37979

However, the temperature control method of Patent Document 1 and the fixing device of Patent Document 2 may not be able to cope with changes in the operating environment of the fixing device and fluctuations in the temperature gradient due to aged deterioration of each member. Furthermore, there is a problem that the control becomes complicated and the cost increases due to the addition of hardware.

In consideration of the above circumstances, it is an object of the present invention to provide an image forming apparatus including a fixing device that reduces overshoot and provides stable fixing performance regardless of changes in the operating environment of the fixing device and aging deterioration of each member. And.

In order to solve the above problems, the image forming apparatus of the present invention is an image forming apparatus including a fixing device for fixing a toner image on a paper conveyed to a pressure region formed between a fixing member and a pressure member. The heat source that heats the fixing member to the target temperature, the temperature gradient of the fixing member within a predetermined section until the target temperature is reached, and the heat source after stopping the heat source each time the fixing device is warmed up. A data storage unit that acquires the temperature rise amount of the fixing member and stores the acquired temperature gradient and the temperature rise amount in correspondence with each other, and the temperature gradient acquired at the time of warming up of the fixing device. The data closest to is selected from the past data accumulated in the data storage unit, and the temperature rise corresponding to the selected temperature gradient is estimated as the temperature rise during warm-up, and the estimated temperature rise is used. It is characterized by including a stop temperature setting unit that sets the temperature at which the heat source is stopped to a temperature lower than the target temperature accordingly.

In the image forming apparatus of the present invention, the stop temperature setting unit may be characterized in that the temperature at which the heat source is stopped is set to a temperature lower than the target temperature by an estimated temperature increase amount.

In the image forming apparatus of the present invention, the data storage unit is classified into a plurality of regions according to the environmental conditions at the time of warming up of the fixing device, and the temperature gradient and the temperature increase amount are the warming of the fixing device. Each time it is up, it is stored in the area corresponding to the environmental condition of the fixing device, and the stop temperature setting unit is acquired from the area corresponding to the environmental condition at the time of warming up at the time of warming up the fixing device. It may be characterized by selecting the data closest to the temperature gradient.

According to the present invention, the amount of temperature rise after the heat source is stopped is estimated with reference to past data, and the temperature at which the heat source is stopped is changed according to the estimated amount of temperature rise. Therefore, environmental changes and deterioration of each member Regardless, overshoot can be reduced.

It is a front view which shows typically the internal structure of the color printer which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the fixing apparatus of the color printer which concerns on one Embodiment of this invention. It is a block diagram which shows the control part in the color printer which concerns on one Embodiment of this invention. It is a graph which shows the temperature change of the fixing roller in the color printer which concerns on one Embodiment of this invention. It is a table which shows the classification of the data storage part in the color printer which concerns on one Embodiment of this invention. It is a flowchart which shows the control at the time of warm-up in the color printer which concerns on one Embodiment of this invention.

Hereinafter, the image forming apparatus of the present invention will be described with reference to the drawings.

First, the overall configuration of the color printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a front view schematically showing the internal configuration of the color printer 1.

The apparatus main body 2 of the color printer 1 includes a paper feed cassette 3 in which the paper S is housed, a paper feed device 5 that feeds the paper S from the paper feed cassette 3, and an image forming unit 7 that forms a toner image on the paper S. A fixing device 9 for fixing the toner image to the paper S, a paper ejection device 11 for ejecting the paper S, and a paper ejection tray 13 for receiving the ejected paper S are provided. Further, the apparatus main body 2 is provided with a control unit 15 that controls an image forming operation described later. Further, an outside temperature sensor 17 is provided on the outside of the apparatus main body 2. The detection result of the outside temperature sensor 17 is input to the control unit 15.

The image forming unit 7 forms a toner image by using each of the intermediate transfer belt 19 that circulates and carries the toner image and the toners (developer) of four colors (yellow, magenta, cyan, and black). An image forming unit 21, four primary transfer rollers 23 for transferring the formed toner image to the intermediate transfer belt 19, and a secondary transfer roller 25 for transferring the toner image transferred to the intermediate transfer belt 19 onto paper. Each image forming unit 21 is provided with an exposure device 27 that exposes the image data based on the image data, and a toner container 29 that houses toner of each color. Each image forming unit 21 includes a photoconductor drum 31 that forms an electrostatic latent image by exposure of the exposure device 27, and a developing device 33 that develops the electrostatic latent image with toner.

A paper S transport path 35 is formed inside the apparatus main body 2. The transport path 35 is formed upward from the paper feeding device 5 through the image forming unit 7 and the fixing device 9 toward the paper discharging device 11. The transport path 35 is provided with a resist roller pair 37 between the paper feeding device 5 and the image forming unit 7.

Next, the image forming operation will be described. In each image forming unit 21 of the image forming unit 7, the exposure device 27 forms an electrostatic latent image on the photoconductor drum 31 based on the image data, and the developing device 33 develops the electrostatic latent image into a toner image. The toner image on each photoconductor drum 31 is primarily transferred to the intermediate transfer belt 19 by each primary transfer roller 23, and a full-color toner image is formed on the intermediate transfer belt 19.

On the other hand, the paper S fed from the paper feed cassette 3 to the transport path 35 by the paper feed device 5 is conveyed to the image forming unit 7 by the resist roller pair 37 at the same timing as the toner image forming operation described above. In the image forming unit 7, the full-color toner image of the intermediate transfer belt 19 is secondarily transferred to the paper S by the secondary transfer roller 25. The paper S to which the toner image is secondarily transferred is conveyed along the transport path 35, and the toner image is fixed on the paper by the fixing device 9. The paper S on which the toner image is fixed is discharged from the paper ejection device 11 to the paper ejection tray 13.

Next, the fixing device 9 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the fixing device.

The fixing device 9 includes a fixing roller 41 as a fixing member, a halogen heater 43 as a heat source for heating the fixing roller 41, and a pressure roller as a pressure member that contacts the fixing roller 41 to form a pressure region N. It includes a 45, a motor 47 for rotating the pressurizing roller 45, and a temperature sensor 49 for measuring the temperature of the fixing roller 41.

The fixing roller 41 has a cylindrical core metal 41a and a release layer 41b provided on the outer peripheral surface of the core metal 41a.

The halogen heater 43 is arranged in the hollow portion of the fixing roller 41. The halogen heater 43 radiates radiant heat to the inner peripheral surface of the fixing roller 41 to heat the fixing roller 41 to a target temperature Tp (for example, 160 ° C.). The halogen heater 43 is driven or stopped by being controlled by the control unit 15.

The pressure roller 45 has a rotating shaft 45a, a heat-expandable elastic layer 45b provided on the outer peripheral surface of the rotating shaft 45a, and a release layer 45c provided on the outer peripheral surface of the elastic layer 45b. The pressure roller 45 is in pressure contact with the fixing roller 41 to form a pressure region N between the rollers 41 and 45.

The motor 47 is connected to the rotating shaft 45a of the pressurizing roller 45. When the motor 47 is driven, the pressurizing roller 45 rotates in a predetermined direction (counterclockwise direction in FIG. 2), and the fixing roller 41 is driven to rotate in the direction opposite to that of the pressurizing roller 45. The drive of the motor 47 is controlled by the control unit 15. The fixing roller 41 may be rotated by the motor 47, and the pressurizing roller 45 may be driven by the fixing roller 41 to rotate.

The temperature sensor 49 is arranged on the outer peripheral surface of the fixing roller 41 at a predetermined interval, and measures the temperature (fixing roller temperature) Tx of the fixing roller 41. The detection result of the temperature sensor 49 is input to the control unit 15.

Next, the control unit 15 will be described with reference to FIGS. 3 to 5. FIG. 3 is a block diagram of the control unit, FIG. 4 is a graph showing the temperature history at the time of warm-up, and FIG. 5 is a table showing a classification table.

As shown in FIG. 3, the control unit 15 includes a data storage unit 51, a stop temperature setting unit 55, and a heater drive unit 57. The data storage unit 51 has a data acquisition unit 52 and a data storage unit 53.

The detection result of the fixing roller temperature Tx measured by the fixing temperature sensor 49 is input to the data acquisition unit 52 when the fixing device 9 is warmed up. An example of the detection result is shown in the graph of FIG. FIG. 4 is a graph showing the relationship between the fixing roller temperature Tx and time. The horizontal axis shows time (seconds), and the vertical axis shows the fixing roller temperature Tx (° C.). Ts on the vertical axis indicates the warm-up start temperature, T1 indicates the measurement start temperature, Ta indicates the determination temperature, T2 indicates the heater stop temperature, T3 indicates the maximum temperature, and Tp indicates the target temperature. Generally, the heater stop temperature T2 and the target temperature Tp are the same temperature. On the horizontal axis, t1 indicates the measurement start time, ta indicates the determination time, t2 indicates the heater stop time, and t3 indicates the maximum temperature arrival time.

The data acquisition unit 52 calculates and acquires the temperature gradient a1 and the temperature rise amount ΔT from the temperature history shown in FIG.

The temperature gradient a1 indicates a temperature change (Ta-T1) from the measurement start temperature T1 to the determination temperature Ta with respect to the time (ta-t1) from the measurement start time t1 to the determination time ta. That is, the temperature gradient a1 = (Ta-T1) / (ta-t1). As an example, the measurement start temperature T1 is 100 ° C., and the determination temperature Ta is 130 ° C.

The temperature increase amount ΔT is the temperature increase amount of the fixing roller 41 after the halogen heater 43 is stopped, and the difference ΔT = T3-T2 between the maximum temperature T3 and the heater stop temperature T2.

In the data storage unit 53, the temperature gradient a1 acquired by the data acquisition unit 52 and the temperature rise amount ΔT are stored in association with each other for each warm-up of the fixing device 9. Further, the detection results of the fixing temperature sensor 49 and the outside temperature sensor 17 are input to the data storage unit 53.

The data storage unit 53 is classified into a plurality of regions as shown in FIG. 5 according to the environmental conditions of the fixing device 9. As an example, the environmental conditions of the fixing device 9 are the warm-up start temperature Ts measured by the fixing temperature sensor 49 and the outside temperature To measured by the outside temperature sensor 17. In this example, the outside temperature To is classified into three, a low temperature range (for example, 10 ° C.), a normal temperature range (for example, 10 to 25 ° C., and a high temperature range (for example, 25 ° C. to)), and the warm-up start temperature Ts. Is classified into three categories: a low temperature range (for example, Ts> 20 ° C.), a normal temperature range (for example, 20 ° C. ≤ Ts <30 ° C.), and a high temperature range (for example, Ts ≥ 30 ° C.). It was classified into nine regions from the first region to the ninth region according to the nine combinations of the temperature To and the warm-up start temperature Ts.

That is, the temperature gradient a1 and the temperature rise amount ΔT that are associated with each other are measured by the warm-up start temperature Ts measured by the fixing temperature sensor 49 and the outside temperature sensor 17 at the time of warm-up in which these values are obtained. It is stored in the area corresponding to the outside temperature To.

For example, when the outside temperature To is 15 ° C. and the warm-up start temperature Ts is 25 ° C., the temperature gradient a1 and the temperature rise amount ΔT are stored in the fifth region.

The stop temperature setting unit 55 sets the heater stop temperature T2. The stop temperature setting unit 55 selects the temperature gradient an closest to the temperature gradient a1 acquired by the data acquisition unit 52 at the time of the current warm-up from the data storage unit 53, and the temperature rise amount corresponding to the selected temperature gradient an. ΔT is estimated as the current temperature rise during warm-up (estimated temperature rise ΔTe). The stop temperature setting unit 55 changes the heater stop temperature T2 based on the estimated temperature rise amount ΔTe.

The heater drive unit 57 drives or stops the halogen heater 43. The heater drive unit 57 stops the halogen heater 43 at the heater stop temperature T2 changed by the stop temperature setting unit 55.

The control during warm-up of the fixing device 9 described above will be described with reference to the flowchart of FIG.

First, in step S1, the heater drive unit 57 drives the halogen heater 43, and the process proceeds to step S2. In step S2, the data acquisition unit 52 obtains the outside temperature To based on the detection result of the outside temperature sensor 17, and then proceeds to S3, and the data storage unit 53 warms up based on the result of the fixing temperature sensor 49. The up start temperature Ts is obtained. As a result, the environmental conditions of the fixing device 9 are selected from the regions shown in the table of FIG.

Next, the process proceeds to step S4, and the data acquisition unit 52 determines whether or not the fixing roller temperature Tx obtained based on the detection result of the fixing temperature sensor 49 has reached the measurement start temperature T1. When it is determined that the fixing temperature roller temperature Tx has reached the measurement start temperature T1, the process proceeds to step S5. In step S5, the data acquisition unit 52 acquires the measurement start time t1 at which the fixing roller temperature Tx reaches the measurement start temperature T1, and proceeds to step S6.

In step S6, the data acquisition unit 52 determines whether or not the fixing roller temperature Tx has reached the determination temperature Ta. When it is determined that the fixing roller temperature Tx has reached the determination temperature Ta, the process proceeds to step S7. In step S7, the data acquisition unit 52 acquires the determination time ta when the fixing roller temperature Tx reaches the determination temperature Ta, and proceeds to step S8.

In step S8, the data acquisition unit 52 calculates the temperature gradient a1 = (Ta-T1) / (ta-t1) from the measurement start temperature T1 to the determination temperature Ta, and proceeds to step S9.

In step S9, the stop temperature setting unit 55 selects the temperature gradient an closest to the temperature gradient a1 calculated in step S8 within the area of the data storage unit 53 selected in step S3, and proceeds to step S10. In step S10, the target temperature setting unit 55 sets the temperature rise amount corresponding to the selected temperature gradient an as the estimated temperature rise amount ΔTe. At the time of the warm-up of the first fixing operation, since the data is not stored in the data storage unit 53, this operation is not performed.

After that, the process proceeds to step S11, and the stop temperature setting unit 55 changes the heater stop temperature T2 with respect to the target temperature Tp based on the estimated temperature rise amount ΔTe. As an example, the changed heater stop temperature T2 can be set to a temperature lower than the target temperature Tp by the estimated temperature increase amount ΔTe. At the time of warming up of the first fixing operation, for example, the heater stop temperature T2 is set as the target temperature Tp. After the heater stop temperature T2 is changed in step S11, the process proceeds to step S12.

In step S12, the data acquisition unit 52 determines whether or not the fixing roller temperature Tx has reached the heater stop temperature T2, and when the heater stop temperature T2 is reached, the process proceeds to step S13.

In step S13, the data acquisition unit 52 records the heater stop time t2 and then proceeds to step S14, and the heater drive unit 57 stops the halogen heater 43.

After that, the process proceeds to step S15, and the data acquisition unit 52 calculates the temperature gradient a = (T2-Ta) / (t2-ta) from the determination time ta to the heater stop time t2, and proceeds to step S16.

In step S16, the data acquisition unit 52 determines from the history of the fixing roller temperature Tx whether or not it is overshooting, that is, whether or not the fixing roller temperature Tx exceeds the target temperature Tp. As an example, the determination as to whether or not the overshoot is performed is determined by the temperature gradient after the fixing roller temperature Tx becomes higher than the heater stop temperature T2 from the history of the fixing roller temperature Tx.

If it is determined in step S16 that the overshoot is overshooting, the process proceeds to step S17, the temperature rise amount ΔT (T3-T2) is acquired, and the process proceeds to step S18.

In step S18, the data acquisition unit 52 associates the temperature gradient a calculated in step S15 with the temperature rise amount ΔT acquired in step S17 and stores it in the selected area of the data storage unit 53. After that, the warm-up control is continued. If it is determined in step S16 that the overshoot has not occurred, the heater stop temperature T2 is appropriately set, so that it is not necessary to save the data in the data storage unit 53.

This operation is performed for each warm-up, and the associated temperature gradient a and the temperature rise amount ΔT are stored in the corresponding area of the data storage unit 53 for each warm-up.

As described above, according to the present invention, the amount of temperature rise after the halogen heater 43 is stopped can be estimated more accurately by referring to the past data stored in the data storage unit 53. .. Then, since the heater stop temperature T2 is changed with respect to the target temperature Tp according to the estimated temperature rise amount, overshoot can be reduced. Therefore, it is not easily affected by environmental changes and deterioration of each member, and the fixing temperature control can be stabilized.

Further, by setting the heater stop temperature T2 to a temperature lower than the target temperature Tp by the estimated temperature rise amount ΔTe, overshoot can be reduced by simple control.

Further, the data storage unit 53 is classified into a plurality of regions according to the environmental conditions of the fixing device 9, and the temperature gradient and the amount of temperature rise are stored in the regions corresponding to the environmental conditions of the fixing device 9. It has become. The temperature history of the fixing roller temperature Tx may change depending on the environmental conditions such as the warm-up start temperature Ts and the outside temperature To. Therefore, by storing the temperature gradient and the amount of temperature rise for each environmental condition, the heater stop temperature can be estimated more accurately.

In the present embodiment, in step S18 of the flowchart of FIG. 5, the temperature gradient a = (T2-Ta) / (t2-ta) from the determination time ta to the heater stop time t2 is stored in the data storage unit 53. Since the time from the determination time ta to the heater stop time t2 is relatively long, it is easy to approximate the temperature change to a straight line, and the temperature gradient can be calculated more accurately. However, the temperature gradient a1 = (Ta-T1) / (ta-t1) from the measurement start time T1 to the determination time ta may be saved.

Further, since the above description of the embodiment of the present invention describes a preferred embodiment of the image forming apparatus according to the present invention, it may be technically preferable with various limitations. The technical scope of the present invention is not limited to these aspects unless otherwise specified to limit the present invention. That is, the constituent elements in the above-described embodiment of the present invention can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. The description of the embodiment of the present invention described above does not limit the content of the invention described in the claims.

1 Color printer (image forming device)
9 Fixing device 41 Fixing roller (fixing member)
43 Halogen heater (heat source)
45 Pressurizing roller (pressurizing member)
51 Data storage unit 55 Stop temperature setting unit

Claims (3)

An image forming apparatus including a fixing device for fixing a toner image on paper conveyed to a pressurized region formed between a fixing member and a pressure member.
A heat source that heats the fixing member to the target temperature,
Each time the fixing device is warmed up, the temperature gradient of the fixing member within a predetermined section until the target temperature is reached and the temperature rise amount of the fixing member after the heat source is stopped are acquired and acquired. A data storage unit that stores the temperature gradient and the amount of temperature rise corresponding to each other,
The data closest to the temperature gradient acquired at the time of warming up the fixing device is selected from the past data accumulated in the data storage unit, and the amount of temperature increase corresponding to the selected temperature gradient is the temperature at the time of warming up. An image forming apparatus including a stop temperature setting unit that estimates the amount of increase and sets the temperature at which the heat source is stopped to a temperature lower than the target temperature according to the estimated amount of temperature increase. .. The stop temperature setting unit is
The image forming apparatus according to claim 1, wherein the temperature at which the heat source is stopped is set to a temperature lower than the target temperature by an estimated temperature increase amount. The data storage unit is classified into a plurality of regions according to the environmental conditions at the time of warming up of the fixing device.
The temperature gradient and the temperature increase amount are stored in the region corresponding to the environmental conditions of the fixing device each time the fixing device is warmed up.
Claim 1 is characterized in that, when the fixing device is warmed up, the stop temperature setting unit selects data closest to the acquired temperature gradient from the region corresponding to the environmental conditions at the time of warming up. Or the image forming apparatus according to 2.

Images