JP2021015191A - Image forming apparatus - Google Patents

Abstract

To prevent dew condensation occurring in a paper ejection path due to water vapor generated from a sheet that is heated by a fixing unit.SOLUTION: An image forming apparatus has fixing means (1) for fixing a toner image on a recording sheet, environment sensor means 1 (8) that measures an environment near the fixing means, paper ejection means (10) that has a plurality of paper ejection paths (2, 4) downstream in a conveyance direction of and above the fixing means, and an environment sensor means 2 (9) that measures an environment of the paper ejection means. When a control unit (20) determines that a dew condensation occurrence condition is met with the environment sensor means 1 (8) and the environment sensor means 2 (9), it performs control of driving the fixing means (1) to heat the paper ejection paths.SELECTED DRAWING: Figure 3(a)

Description

The present invention relates to an image forming apparatus such as a copying machine and a laser beam printer apparatus using an electrophotographic method, and particularly to a configuration in which a paper transport path is provided above the fuser.

Conventionally, in an image forming apparatus using an electrophotographic method, a thermal roller method is often used in order to heat-fix a toner image transferred onto a recording material (paper).

In addition, due to the space saving of the office, the installation area of the image forming apparatus is also required. Corresponding to this, the configuration in which the image forming apparatus has a paper transport path above the fuser can save the installation area as compared with the configuration in which the paper transport path is provided on the side of the main body. On the other hand, in this configuration, since the paper transport path on the downstream side is located above the fuser, the moisture of the paper easily enters the transport path, and a proposal has been made to prevent dew condensation due to the moisture (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-274835

However, in the prior art disclosed in Patent Document 1 described above, the paper transport roll during single-sided printing and double-sided printing is idled, and the water vapor rising from the fuser is shut out from the double-sided printing transport path. This prevents dew condensation inside the paper transport device.

As a result, the water vapor in the single-sided printing unit is accumulated in the unit, and the temperature inside the unit also rises. Therefore, when double-sided printing is performed after long-time single-sided printing, the paper for double-sided printing passes through the path in the unit, so that moisture is absorbed more than usual. Since the moisture-absorbed paper passes through the low-temperature double-sided printing unit, it is rapidly cooled in the double-sided printing unit and becomes more moist paper, which increases the transport resistance and causes transport defects such as jams and wrinkles. ..

In order to solve the above problems, the image forming apparatus according to the present invention is
A fixing means for fixing the toner image on the recording paper to the recording paper, a first environmental sensor for measuring the environment in the vicinity of the fixing means, and a plurality of paper ejection paths downstream and above the fixing means in the transport direction. The paper ejection means has a paper ejection means and a second environmental sensor means for measuring the environment of the paper ejection means, and the control unit determines that the dew condensation generation condition is determined by the first environmental sensor and the second environmental sensor. At that time, the printing job is temporarily stopped, the fixing means is driven, and control for warming the paper ejection path is executed.

According to the image forming apparatus according to the present invention, when the occurrence of dew condensation is detected, the printing job is temporarily stopped, the fixing apparatus is driven, and the paper ejection path downstream in the transport direction is controlled to be warmed. As a result, it is possible to dehumidify the inside of the transport path, prevent dew condensation, and prevent transport defects such as jams and wrinkles.

The figure which shows the structure of the image forming apparatus The figure which shows the structure of the image forming apparatus flowchart flowchart

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration and a paper ejection device 10 from fixing to paper ejection of the image forming apparatus of the present invention.

The fixing device 1 in the paper ejection device 10 heats and pressurizes the paper in order to fix the toner image transferred on the paper. The first paper ejection route 2 is a paper ejection route for the paper having the fixed image ejected from the fixing device 1. The first transport roller pair 3 is a roller pair for outputting the paper to the outside of the apparatus through the first paper ejection path 2. The second paper ejection route 4 is a route for ejecting paper when the paper is not ejected to the first paper ejection route 2 according to the user's paper ejection route setting.

The second transport roller pair 5 is a roller pair for guiding the paper to the second paper ejection path 4. The paper discharge guide 6 is a member for reversing the paper conveyed by the second transfer roller pair 5 and directing the paper to the output port of the second transfer path 4. The third roller pair 7 is a paper ejection roller pair for outputting the paper whose transport direction has been changed by the paper ejection guide 6 to the paper ejection port of the second transport path 4. The first environment sensor 8 is a sensor that detects the temperature and humidity around the fixing device 1. The second environment sensor 9 is a sensor that detects the temperature and humidity around the second paper ejection path 4. The first output path sensor 11, the second output path sensor 12, and the third output path sensor 13 are sensors that detect the position of the printing paper in the output path.

FIG. 2 is a block diagram for controlling the configuration of the image forming apparatus of the present invention from fixing to paper ejection.

The control unit 20 controls the paper ejection device 10 of FIG. The paper ejection unit drive circuit 21 is an electric circuit that drives the fixing device 1, the first transfer roller pair 3, the second transfer roller pair 5, and the third transfer roller pair 7 in FIG. The temperature detection signal 22 is a signal indicating the temperature of the fixing device 1, and the control unit 20 controls the temperature of the fixing device 1 by the signal.

3 (a) and 3 (b) are flowcharts showing the control of the present embodiment.

FIG. 3A shows a flow in which the control unit 20 monitors the signals from the first environment sensor 8 and the second environment sensor 9. FIG. 3B is a flowchart showing the main body control of the present embodiment.

In FIG. 3A, in S301, the control unit 20 sets, as an initial setting, dew condensation FLAG '0' indicating that the dew condensation generation condition is not met. The control unit 20 receives the output of the first environment sensor 8 at S302 and the output of the second environment sensor 9 at S303. In S304, the control unit 20 determines whether or not the condition is a dew condensation occurrence condition based on the data of each environmental sensor obtained in S302 and S303. When the control unit 20 determines that the condition is a dew condensation occurrence condition, the dew condensation FLAG is set to "1" in S305, indicating that the dew condensation generation condition is satisfied. Next, in S306, if printing is in progress, the process returns to S302, and the control unit 20 waits for the printing to pause, such as stopping between papers, while obtaining the information of each sensor. If printing is not in progress in S306, the control unit 20 drives the fixing device 1, and the heat generated by the fixing device 1 warms the first paper ejection path 2 and the second paper ejection path 4 to cause dew condensation. To prevent.

If the control unit 20 determines in S304 that the conditions are not dew condensation occurrence conditions, and if the dew condensation FLAG is '1' in S308, the drive of the fixing device 1 is stopped, and the first paper ejection path 2 and the second Stop warming the output path 4. If the condensation FLAG is '0', the process returns to S301.

In FIG. 3B, when the print job is input, the control unit 20 confirms whether the dew condensation FLAG is '0' in S310. When the FLAG is '1', the process proceeds to S311 and the control unit 20 confirms the states of the paper ejection path sensors 11, 12 and 13 and verifies whether or not they are in the jam state. If it is not in the jam state, the control unit 20 waits without performing the print job until the dew condensation FLAG becomes ‘1’. In the case of a jam state in S311 the control unit 20 waits for the jam release in S312. When the jam is released in S312, the control unit 20 reduces the paper transport speed in S313 and sets the control to lower the temperature of the fixing device 1 at the time of printing.

In S310, when the dew condensation FLAG is '0', the control unit 20 shifts to S314, drives the paper ejection unit drive circuit 21 and the fixing device 1, and starts printing. In S315, the control unit 20 waits for the end of printing one sheet. When finished, the control unit 20 confirms that the dew condensation FLAG is '1' in S316. When the dew condensation FLAG is '1', in S317, the control unit 20 confirms that the temperature detection signal 22 indicates that the fixing device 1 has become hot, or that printing is temporarily stopped due to other factors. , Verify if printing can be paused. If it is not possible to pause, the process proceeds to S319. If printing can be paused, the process proceeds to S318. At S318, the control unit 20 pauses printing, returns to S316, and stops printing until the dew condensation FLAG becomes '0'.

If the dew condensation FLAG is '0' in S316, the control unit 20 confirms the presence or absence of a print job in S319, and if there is a print job, the control unit 20 continues to execute the print job in S320, and S315. Return to. When the print job ends, it ends as it is.

As described above, after the jam occurs, the printing speed is reduced and the temperature of the fixing device 1 is controlled to be lowered to suppress the amount of water vapor generated from the printing paper and prevent the occurrence of dew condensation on the paper ejection guide 6. be able to. Further, by constantly verifying the occurrence of dew condensation, pausing printing, driving the fixing device 1, and warming the inside of the paper ejection path, it is possible to prevent the occurrence of dew condensation in the paper ejection guide 6. As a result, the transport resistance due to dew condensation is eliminated in the paper ejection guide 6 or the paper ejection path, and jam can be prevented.

In this embodiment, when the condition for dew condensation occurs, the fixing device 1 is driven to warm the paper ejection path except during printing. Further, the output path may be switched during the print job, that is, the second output path 4 may be switched to the first output path 2 during the print job to prevent jamming. (By outputting the printing paper that generates water vapor after fixing from a shorter paper ejection path, it is possible to prevent water vapor from being trapped in the paper ejection device 10.)

1 Fixing device, 2 First paper transport path, 4 Second paper transport path,
6 Paper ejection guide, 8 1st environment sensor, 9 2nd environment sensor,
10 Paper ejection device, 20 Control unit

Claims (4)

A fixing means for fixing the toner image on the recording paper to the recording paper,
A first environment sensor means for measuring the environment in the vicinity of the fixing means, and
A paper ejection means having a plurality of paper ejection paths downstream of the fixing means in the transport direction and above the fixing means.
A second environment sensor means for measuring the environment of the paper ejection means, and
Control unit and
Have,
When the control unit determines that the dew condensation occurrence condition is determined by the first environmental sensor and the second environmental sensor, the fixing means is driven to execute the control to warm the paper ejection path and slow down the process speed. An image forming apparatus characterized in that the above is performed. The image forming apparatus according to claim 1, wherein when the control unit determines that a dew condensation state is formed, the control and the paper ejection path are switched. The image forming apparatus according to claim 1 or 2, wherein the process speed is slowed down and dew condensation suppression control is performed when the user energy saving mode is set. The image forming apparatus according to any one of claims 1 to 3, wherein when the control for warming the paper ejection path is performed, the temperature of the fixing means is controlled at a temperature lower than that at the time of print output. ..