JP5413044B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, and more particularly to an image forming apparatus having a fixing mechanism for fixing a toner image on a recording material by heat pressure.

In an image forming apparatus such as a laser printer or a copying machine, toner is attached to an electrostatic latent image formed on a photosensitive drum, and this is transferred to a recording material for printing. The recording material is conveyed to a fixing device provided in the image forming apparatus, and the toner is fixed on the recording material by melting the toner in the fixing device. The fixing device is configured by combining a fixing roller having a fixing heater (heat source) and a pressure roller.
In such an image forming apparatus, when the recording material is in a low temperature state, the recording material is deprived of heat and the fixing rate of the toner is lowered, so that there is a problem that high quality image quality cannot be obtained.

  On the other hand, for the purpose of preventing poor fixing of toner at a low temperature of the recording material, a method of controlling the temperature of the fixing device according to the temperature of the recording material in the paper feeding device (paper feeding tray), A technique for heating a recording material by using waste heat or using a dedicated heating device has been proposed (for example, see Patent Document 1). In addition, a method for measuring the temperature of a recording material with a paper feed tray and heating it at a low temperature and a technique for predicting the amount of heat absorbed when the recording material passes through the fixing device and adjusting the fixing temperature in advance are already known. Yes.

However, an apparatus that heats the recording material in the paper feed tray needs to improve the hermeticity of the paper feed tray in order to efficiently heat the recording material. In an image forming apparatus having a plurality of paper feed trays, installation of a sensor for measuring the temperature of a recording material and a heating device for each paper feed tray increases the installation cost and increases the required installation space. There's a problem.
Furthermore, in the case of recording materials that have been left for a long time, especially when the surface layer is affected by the surrounding environment, for example, when a recording material that has been in a low-temperature environment is fed immediately after being supplied to the paper feeder. In some cases, the inside of the paper feeding device or the fixing device is not sufficiently heated, and the recording material does not reach an appropriate temperature, resulting in toner fixing failure.

  Therefore, an object of the present invention has been made in view of the above problems in the prior art, and can reduce the installation cost and installation space of the temperature measuring device and the heating device of the recording material. An object of the present invention is to provide an image forming apparatus capable of preventing a toner fixing defect even if printing is performed immediately after being supplied to a paper feeding device without extremely reducing productivity.

In order to solve the above problems, an image forming apparatus according to the present invention is as follows.
[1] A plurality of paper feed devices that can be opened and closed;
Means for managing the cumulative number of paper sheets fed since each of the paper feeders is closed;
Means for stopping the recording material on a conveying path of the recording material;
Means for measuring the temperature of the stopped recording material;
Means for changing a control parameter in accordance with a result of the temperature measurement and controlling at least one of the heating temperature of the fixing device and the paper feeding device;
A display device capable of input operation,
When at least the first recording material is fed,
The recording material is stopped on the conveyance path to measure the temperature, and when the measured temperature is out of a specified range, whether to perform image formation or to cancel is displayed on the display device,
When the user selects to execute image formation, the control parameter is changed, and the heating temperature of at least one of the fixing device and the paper feeding device can be controlled .
[2 ] When the recording material with the cumulative number of sheets fed after the second sheet is fed, similarly to the first sheet, the recording material is stopped on the conveyance path to measure the temperature, and the measured temperature Is outside the specified range, it is determined whether or not to perform image formation. When image formation is performed, the control parameter is changed, and the heating temperature of at least one of the fixing device and the paper feeding device is changed. The image forming apparatus according to [1 ], wherein the image forming apparatus can be controlled.

  According to the present invention, it is possible to reduce the installation cost and installation space of the recording material temperature measuring device and the heating device, and productivity can be improved even when printing is performed immediately after the recording material in a low temperature state is supplied to the paper feeding device. It is possible to provide an image forming apparatus capable of preventing toner fixing failure without being extremely lowered.

As an effect of the present invention, according to the first aspect of the invention, installation costs of the temperature measuring device in an image forming apparatus having a plurality of paper feeding device by providing a temperature measuring device for a recording material conveyance path (resist portion) The installation space can be reduced, and the temperature of the recording material is measured during the initial (surface) feeding of each paper feeder, and the control parameters are changed, and then the paper feed tray is heated and the fixing temperature is adjusted. Therefore, even if the recording material is left for a long time, it can be set to an appropriate temperature, and toner fixing failure can be prevented.
In addition, occurrence of toner fixing failure can be prevented by stopping printing.
According to the invention of claim 2 can be specified by an input operation whether the user can inform the potential of the toner fixing failure to Yu chromatography The, also to continue printing.
Further, occurrence of toner fixing failure can be avoided by a method desired by the user.
According to the invention of claim 3, by making changes in the temperature measurement and control parameters continue to the recording material, it is possible to prevent more reliably the toner fixing failure, it is possible to obtain a high quality image .

1 is a schematic cross-sectional view illustrating an example of a configuration of an image forming apparatus of the present invention. 6 is a flowchart illustrating an example of a flow of management of the cumulative number of sheets fed in the image forming apparatus of the present invention. 6 is a flowchart illustrating an example of a flow of control parameter change in the image forming apparatus of the present invention. 6 is a flowchart illustrating an example of a flow from determination of a recording material temperature measurement to control parameter change in the image forming apparatus of the present invention.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

FIG. 1 is a schematic view (cross-sectional view) showing an embodiment of the image forming apparatus of the present invention.
As shown in FIG. 1, the image forming apparatus of the present invention is a full-color image forming apparatus composed of four colors of yellow, magenta, cyan, and black, and image forming units 20a, 20b, 20c for these four colors, and 20 d (hereinafter simply referred to as 20) is disposed along the running direction of the transfer belt 17. The image forming unit 20 includes photosensitive members 22a to 22d as image carriers, drum chargers 23a to 23d, exposure devices 24a to d, developing devices 25a to d, transfer devices 26a to 26d, and cleaning devices 27a to 27d, respectively. I have.
The image forming unit 20 forms toner images of four colors of yellow, magenta, cyan, and black, respectively, and is superimposed on the transfer belt 17 to form four color full-color images.

  The image forming apparatus according to the present invention includes a plurality of sheet feeding devices including a sheet feeding tray 19 and a bottom heating device 18, a unit for managing the cumulative number of sheets fed by the recording material 30 from the sheet feeding device, and the recording material Gate means 12 for stopping the recording material on the transport path, a temperature measuring device 13 for measuring the temperature of the stopped recording material, and a control parameter changed according to the temperature measurement result And a means capable of controlling the heating temperature of at least one of the fixing device 16 and the heating device 18 of the paper feeding device.

The recording material 30 supplied (stacked) to the paper feed tray 19 is managed for the number of paper fed for each paper feed tray (described later with reference to FIG. 2).
The leading end of the recording material 31 fed on the transport path hits the gate means 12, and the rear end side is fed downstream by the transport roller pair 10 in that state. Is done. Due to the excessive feeding in the state of being abutted against the gate means 12, the front end of the recording material 31 is corrected for the oblique displacement. In this state, the registration roller pair 11 is closed and the recording material 31 is pressed, so that the leading end of the recording material 31 is positioned at the position of the gate means 12. Next, the gate unit 12 is opened so as to be retracted from the conveyance path, and the conveyance roller pair 10 is also separated, whereby the recording material 31 returns to a state without bending. That is, the positional deviation on the upstream side of the registration roller pair 11 is also corrected.

For the recording material 31 that is stopped in a state in which the positional deviation is corrected, the control unit performs the temperature measurement execution determination process based on the accumulated number of sheets fed from the conveyance information of the recording material 31 and the measured temperature. Processing such as control parameter change is performed (described later with reference to FIGS. 3 and 4).

When the recording material 31 is the first cumulative number of sheets fed, the temperature of the recording material 31 is measured using a temperature measuring device 13 such as a thermopile.
As a result of determining whether the measured temperature of the recording material 31 is within the specified range or outside the specified range, if it is outside the specified range, the control parameter is changed. By changing the control parameter, the heating temperature of at least one of the fixing device 16 and the sheet feeding tray heating device 18 is controlled.
When the cumulative number of sheets fed is other than the first sheet, it is not necessary to measure the temperature of the recording material, and it may be appropriately measured according to the required image quality. When the temperature measurement is performed only when the cumulative number of fed sheets is the first sheet, it is preferable in terms of productivity because continuous printing can be performed without stopping the subsequent conveyance of the recording material.

  The timing is adjusted to the toner image conveyed on the transfer belt 17, and the registration roller pair 14 is set to a predetermined timing, that is, a predetermined position at the front end in the belt rotation direction of the toner image on the transfer belt 17 and the front end in the conveyance direction of the recording material 31. At the timing when the position matches, the recording material 31 starts to be conveyed in the direction of arrow C.

The image formed on the transfer belt 17 reaches the transfer device 15 and is simultaneously transferred to the recording material 31 conveyed to the portion facing the secondary transfer belt by the action of a high voltage applied to the transfer device 15. Is done.
The toner image transferred to the recording material 31 is heated when passing through the fixing device 16 and is melt-pressed onto the recording material 31.
By the above flow, an image is formed on the recording material.

FIG. 2 is a flowchart showing an example of the flow of management of the cumulative number of fed sheets in the image forming apparatus of the present invention.
In the processing shown in FIG. 2, the opening and closing of the paper feed tray is regarded as the supply (stacking) of the recording material into the tray, and the supply is regarded as being completed when the paper feed tray is in the “closed state”. Since the image forming apparatus of the present invention has a plurality of paper feeding devices, it is preferable that the tray opening / closing of each paper feeding device can be detected.
When a print command is received from the user, paper is fed from a paper feed tray on which recording materials of the corresponding size are stacked, and at the same time, the cumulative number of sheets supplied for each paper feed tray is added as conveyance information.

  The cumulative number of sheets fed is determined as the first sheet feeding after the sheet feeding tray is in the “closed state” (S11). When the sheet feeding is the first sheet feeding, the recording material is supplied (stacked). The cumulative number of sheets fed in the corresponding sheet feeding tray is initialized, and information of the first sheet (n = 1) is added (S12). If it is not the first paper feed, the cumulative number of fed sheets is updated to obtain information obtained by adding 1 to the numerical value of the already accumulated number of fed sheets (S13).

FIG. 3 is a flowchart showing an example of the flow of control parameter change in the image forming apparatus of the present invention.
FIG. 3 illustrates a case where temperature measurement is performed on the conveyance path (registration unit) for the first recording material having the cumulative number of sheets described in FIG.
After the recording material is supplied (stacked) to the paper feed tray, the recording material first fed from the paper feed tray is the cumulative feed number. When it is determined that the number of sheets is the first one (S21) and the conveyance path (registration unit) is reached, the conveyance is stopped and the temperature is measured (S22). In the temperature measurement result, it is determined whether the recording material is in a temperature range in which toner fixing failure occurs, that is, outside the specified range (S23), and when it is out of the specified range, the control parameter is changed ( S24), at least one of the control temperature of the fixing device and the heating temperature of the heating device of the paper feed tray that feeds the recording material is adjusted, and simultaneously the conveyance of the recording material is resumed.

In the recording material temperature measurement determination process, depending on the priority of the image quality, the determination of the temperature measurement execution based on the cumulative number of sheets fed and the process after the determination of the measurement result can be appropriately changed.
For example, in the determination of the cumulative number of sheets fed, by not specifying the cumulative number of sheets fed, the temperature of the recording material can be continuously measured after the first sheet and the control parameters can be changed in a timely manner. Further, after the temperature measurement result is determined, if it is determined that the recording material is in a temperature range that causes toner fixing failure, the image formation can be stopped as an error. Furthermore, in an image forming apparatus having a display device capable of input operation, such as an operation panel, after the temperature measurement result is determined, only the measurement result determination result is displayed on the display device without causing an error (discontinuation of image formation). Thus, printing can be continued, and any one of these processes can be switched depending on the degree desired by the user. This is shown in FIG.
In addition to the display of the determination result, options for subsequent processing can be displayed, and the user can select and instruct the operation panel.

FIG. 4 is a flowchart showing an example of the flow from the determination of the temperature measurement of the recording material to the change of the control parameter in the image forming apparatus of the present invention.
It is determined whether or not the cumulative number of sheets fed is the first sheet (S31), and if it is not the first sheet, it is determined whether or not the second and subsequent sheets are set to be measured (S32) and corresponds to the measurement target. In this case, the temperature of the recording material is measured (S33).
In the temperature measurement result, it is determined whether the recording material is in a temperature range causing toner fixing failure, that is, outside the specified range (S34), and when the measured temperature is outside the specified range, image formation is performed as error processing. It is determined whether or not to cancel (S35). When performing image formation, it is determined whether or not to notify the user that the measured temperature is outside the specified range (S36), and processing for automatically changing the control parameter without notification is performed. At the same time, the control parameter is changed in accordance with the control parameter change execution judgment (S37) (S38), and at the same time, at least one of the control temperature of the fixing device and the heating temperature of the heating device of the paper feed tray that feeds the recording material is adjusted. Then, the conveyance of the recording material is resumed.

  As described above, according to the image forming apparatus of the present invention, it is possible to reduce the installation cost and installation space of the recording material temperature measuring device and the heating device, and immediately after supplying the recording material in a low temperature state to the paper feeding device. Even with this printing, it is possible to prevent toner fixing failure without drastically reducing productivity.

DESCRIPTION OF SYMBOLS 10 Conveying roller pair 11 Registration roller pair 12 Gate means 13 Temperature measuring device 14 Conveying roller pair 15 Transfer device 16 Fixing device 17 Transfer belt 18 Heating device 19 Paper feed tray 20 Image forming unit 22 Photoconductor 23 Drum charger 24 Exposure device 25 Developing device 26 Transfer device 27 Cleaning device 30 Recording material (stacked in paper feed tray)
31 Recording material (on transport path)

JP-A-4-338790

Claims (2)

A plurality of paper feeders that can be opened and closed;
Means for managing the cumulative number of paper sheets fed since each of the paper feeders is closed;
Means for stopping the recording material on a conveying path of the recording material;
Means for measuring the temperature of the stopped recording material;
Means for changing a control parameter in accordance with a result of the temperature measurement and controlling at least one of the heating temperature of the fixing device and the paper feeding device;
A display device capable of input operation,
When at least the first recording material is fed,
The recording material is stopped on the conveyance path to measure the temperature, and when the measured temperature is out of a specified range, whether to perform image formation or to cancel is displayed on the display device,
An image forming apparatus, wherein when the user selects to execute image formation, the control parameter can be changed to control the heating temperature of at least one of the fixing device and the paper feeding device. When the recording material whose cumulative number of papers is fed is the second or later, like the first paper, the recording material is stopped on the conveyance path and the temperature is measured. When it is out of the range, it is determined whether or not to perform image formation, and when performing image formation, the control parameter can be changed to control the heating temperature of at least one of the fixing device and the paper feeding device. The image forming apparatus according to claim 1 .

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