JP2002304079A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device equipped with constitution capable of accurately warning the exchanging time of a coating unit by accurately grasping the point of time when the coating unit is newly exchanged in deciding the exchanging time of the coating unit with the number of image forming times as reference. SOLUTION: This fixing device fixing toner included in an unfixed image carried on a recording medium is equipped with a fixing member 2 heating in contact with the toner and the coating unit 13 capable of supplying a release agent to the surface of the member 2 and being exchanged. The unit 13 is equipped with the constitution 14 for discriminating that it is exchanged to the new one according to state change caused by atmospheric temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fixing device and an image forming apparatus using the same, and more particularly, to an offset preventing mechanism generated during fixing.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile, a printer, and a printing machine, an unfixed image transferred and carried on a recording medium such as paper is fixed to produce a copy or print output. Sometimes. In a device used for fixing, a pair of rollers are arranged to face each other, one roller is used as a heating roller, and the other roller is used as a pressure roller of a recording medium, or a pair of rollers is used instead of a heating roller. There is a configuration in which a belt wound around a roller is used, and a pressure roller faces the belt.

The toner to be fixed may cause an offset phenomenon in which the toner is reversely transferred to a contacting member due to a change in viscoelasticity upon melting. For this reason, a releasing agent such as silicone oil is supplied to a roller or a belt on the side that comes into contact with the toner to the fixing device.

As a supply mechanism of the release agent, a release agent contained in a tank is applied to the surface of a roller or a belt using a felt or the like, or an application using an osmotic pressure of the release agent. There is a type in which a release agent impregnated in a pad or the like provided in the unit is transported to a roller or a belt and applied.

On the other hand, since the release agent is an object to be consumed,
Depending on the remaining amount, the amount of application may be insufficient and an appropriate offset prevention effect may not be obtained. For this reason, conventionally, measures have been taken in which the remaining amount is detected, and when the remaining amount reaches a specified amount, the release agent can be refilled into the tank or the application unit can be replaced.

[0006]

In the case where the coating unit containing the pad impregnated with the release agent is replaced in response to the detection of the remaining amount of the release agent, the release agent directly contained in the pad is used. It is difficult to detect the remaining amount. Therefore, it has been proposed to initialize the number of times of image formation after the replacement, count the number of times of image formation restarted after the replacement, and calculate the replacement time when the counted value reaches a predetermined value (for example, Japanese Patent Laid-Open No. Hei 8 (1996)). -87214).

However, the above-mentioned publication only discloses that the counting of the number of image formation is started on the assumption that the replacement has been performed. No disclosure has been made. Therefore, if the replaced coating unit cannot be accurately determined, the count value of the number of times of image formation itself may not match the actual consumption of the release agent. May be erroneously determined. In addition, when identifying a newly exchanged coating unit, for example, a special structure that mechanically destroys an identification portion provided in the coating unit when the fixing unit is equipped is used. However, in such a case, not only a special structure is required, but also if the fixing unit is installed in a state where it has been mechanically broken by mistake, A problem that the identification cannot be performed occurs. If an erroneous replacement time is warned when the fixing device is installed in the fixing device, an offset is likely to occur and a defective image is generated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new fixing device, particularly in view of the problem of determining the replacement timing of a release agent supply section, when determining the replacement timing of a coating unit based on the number of times of image formation. It is an object of the present invention to provide a fixing device and an image forming apparatus having a configuration capable of accurately ascertaining the point of time when the coating unit has been replaced and thereby accurately warning the time of replacement of the coating unit.

[0009]

According to the first aspect of the present invention,
In a fixing device for fixing a toner contained in an unfixed image carried on a recording medium, a fixing member that contacts and heats the toner, and a release agent can be supplied to the surface of the fixing member and can be exchanged. An application unit, wherein the application unit is provided with a configuration for determining that a new unit has been replaced based on a state change caused by an ambient temperature.

According to a second aspect of the present invention, the coating unit is provided with a temperature fuse that can be blown at a predetermined atmospheric temperature, and the temperature fuse is located in a determination circuit of the newly replaced coating unit. When the output signal of the determination circuit changes under a predetermined condition, it is characterized in that it is determined that the application unit is newly replaced.

[0011] The invention according to claim 3 is characterized in that the temperature fuse provided in the coating unit is disposed at the outermost end within the range of the maximum sheet passing width in the coating unit.

According to a fourth aspect of the present invention, the discriminating circuit is provided in a control unit, and the control unit is connected to the temperature fuse on an input side, and has an alarm unit and an image forming frequency counting unit on an output side. Is connected, and when it is determined that the image sensor is newly replaced due to a change in the state of the output signal from the temperature fuse, the number of times of image formation is reset and counting is restarted.

The invention according to claim 5 is characterized in that the control unit checks the replacement of the coating unit for a new one, and warns the replacement of the coating unit when the number of image formations reaches a predetermined value after the replacement of the new one. And

According to a sixth aspect of the present invention, there is provided an image forming apparatus using the fixing device according to the first aspect of the present invention.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one of image forming apparatuses to which a fixing device according to an embodiment of the present invention is applied. As the image forming apparatus shown in FIG. 1, a copying machine or a printer capable of forming a full-color image is used. Other image forming apparatuses include a facsimile apparatus capable of performing the same image forming processing as the above-described copying machine and printer based on a received image signal. Note that the image forming apparatus includes not only the above-described color image but also an apparatus which targets a single-color image.

The image forming apparatus 20 shown in FIG. 1 sequentially transfers images for each color separation onto the same intermediate transfer member, and copies the image superimposed on the intermediate transfer member onto a sheet-like recording medium such as paper. A batch transfer method is used. In FIG.
The image forming apparatus 20 includes the following devices.
Image forming apparatus 21 that forms an image for each color according to a document image
C, 21Y, 21M, 21BK, and each image forming device 21C,
A transfer device 22 disposed opposite to 21Y, 21M, 21BK, and image forming devices 21C, 21Y, 21M, 21B;
A manual tray 23, sheet cassettes 24, 24 as manual sheet supply means for supplying various sheet media to a transfer area where K and the transfer device 22 face each other;
3. A registration roller 30 for supplying the sheet-like medium conveyed from the paper feed cassettes 24, 24 at the timing of image formation by the image forming apparatuses 21C, 21Y, 21M, 21BK, and a sheet-like medium after transfer in the transfer area. The fixing device 1 fixes a medium.

The image forming apparatus 20 includes plain paper (hereinafter simply referred to as plain paper) generally used for copying and the like, 90K paper such as an OHP sheet, a card, and a postcard, and a basis weight of about 10
Any of so-called special sheets (hereinafter simply referred to as “special sheets”) having a heat capacity larger than that of paper, such as thick paper of 0 g / m ² or more, and envelopes, can be used as the sheet-shaped medium.

Each of the image forming devices 21C, 21Y, 21M, 21
BK develops each color of cyan, yellow, magenta, and black, and uses different colors of toner. However, since the configuration is the same, the image forming apparatus 21C
Of the image forming apparatus 21C, 21Y, 21M, 21B
This will be described as a representative of K.

The image forming apparatus 21C includes a photosensitive drum 25C as an electrostatic latent image carrier, a charging device 27C, a developing device 26C, and a cleaning device 28C which are sequentially arranged along the rotation direction A of the photosensitive drum 25C. Having a charging device 2
A known configuration for receiving the exposure light 29C between the developing device 7C and the developing device 26C is used. The electrostatic latent image carrier may be in a belt shape in addition to a drum shape. In the image forming apparatus 20 shown in FIG. 1, since the transfer device 22 extends obliquely, the space occupied by the transfer device 22 in the horizontal direction can be reduced.

In FIG. 2, a fixing device 1 includes an endless fixing belt 2 for conveying a sheet-like medium on which toner is fixed, a heating roller 3 over which the fixing belt 2 is stretched and drives the fixing belt 2, and a fixing device. A pressure roller 5 disposed opposite to the fixing roller 4 via the fixing belt 2
And heaters 6 and 7 provided inside the heating roller 3 and the pressure roller 5, and a temperature detection unit that is disposed to face the heating roller 3 via the fixing belt 2 and detects the temperature of the fixing belt 2. A thermistor 8. In the present embodiment, the fixing belt 2 forms one component as a fixing member.

The heating roller 3 is urged by an elastic body (not shown) such as a spring so as to be separated from the fixing roller 4 so as to apply an appropriate predetermined tension to the fixing belt 2. The fixing roller 4 has a metal core 9 and a heat-resistant porous elastic layer 10 covering the metal core 9, and the metal core 9 is rotationally driven by a driving unit (not shown) by its end shaft 11. Thus, the fixing roller 4 is driven to rotate, and the fixing belt 2 is driven by the driven rotation of the heating roller 3.

The pressure roller 5 is urged by an elastic body (not shown) such as a spring in a direction in which the pressure roller 5 comes into pressure contact with the fixing roller 4. The pressure roller 5 has an axis of the fixing roller 4 as an apex, and an axis of the fixing roller 4 and an axis of the heating roller 3.
And the pressing roller 5 are in contact with the fixing roller 4 such that the angle between the two straight lines connecting the pressing roller 5 and the pressing roller 5 forms an acute angle. As a result, the first fixing portion A in which the pressure roller 5 abuts on the fixing belt 2 only at a portion not facing the fixing roller 4, and the second fixing portion A in which the pressure roller 5 abuts on the fixing roller 4 via the fixing belt 2 And a fixing portion B of
An area for holding and heating the sheet-like medium is configured.

The fixing belt 2 is provided with a structure for supplying a release agent such as silicone oil. 2, in the vicinity of the fixing belt 2, an application roller 12 that is rotatable in conjunction with the fixing belt 2 is provided in contact therewith.

In the vicinity of the application roller 12, an application unit 13 having a pad 13A impregnated with a release agent is provided. The coating unit 13 is formed of a housing that can swing about the support shaft 13B as a fulcrum and the coating roller 12 side as a swing end, and supports a part extended from the pad 13A on a part of the housing wall. An application section 13C is formed, and the application section 13C comes into contact with and separates from the application roller 12. When the application unit 13C comes into contact with the application roller 12, the release agent is delivered by the osmotic pressure from inside the pad 13A.

Inside the coating unit 13, a temperature fuse 14 is provided near the bottom surface facing the fixing belt 2. The temperature fuse 14 is located at the end of the coating unit 13 within the range of the maximum sheet passing width.
3 is easily affected by the temperature from the fixing belt 2 located on the bottom surface side, and is within the range of the maximum sheet passing width. It is easier.

The temperature fuse 14 forms a part of a discriminating circuit 15 for the newly replaced coating unit shown in FIG. 3, and the discriminating circuit 15 is provided in the control unit 16.
In FIG. 3, a determination circuit 15 is provided with a power source (in FIG.
C) is connected to the input side of the control unit 16 which is connected to a power supply path from the power supply line to the coating unit 13. Therefore, the coating unit 13 is provided with a connector used for connection with the control unit 16. Temperature fuse 14
Are connected to the power supply VCC and to the control unit 16.

The control unit 16 has a temperature fuse 14 on the input side.
Is connected so that a change in the state of the output signal at the time of fusing is input. An alarm unit 17 and a counter 18 for counting the number of times of image formation are connected to the output side.

The control section 16 determines that the case where the temperature fuse 14 has blown and the output signal has changed from the state before the blow has changed from a high level to a low level as indicated by P in FIG. 4 as a predetermined change state. By doing so, the count value of the counter 18 is reset.

In FIG. 4, the output signal from the temperature fuse 14 is at a low level before being blown (indicated by LO in the figure).
And when it is blown, a high level (in FIG.
The control unit 16 changes the high-level to low-level, in other words, the blown temperature fuse 14 from the coating unit 13.
When the application unit 13 is changed to a state where it has not been blown by a new replacement, the application unit 13 is determined to be newly replaced.

The controller 16, which determines that the coating unit 13 has been newly replaced, resets the count value of the number of times of image formation at the time of replacement, and restarts counting again, whereby a preset replacement is performed. The number of times and the number of times of counting are compared, and if they match, an alarm prompting replacement is issued. In this case, the number of replacement times is pad 1
This corresponds to a time point before the time when the release agent completely disappears in 3A.

Since the present embodiment has the above configuration,
The operation of the control unit 16 will be described with reference to the flowchart shown in FIG. Temperature fuse 14 at this stage
Is input (ST1), the control unit 16
The state of the signal change is determined in (ST2). In this determination processing, it is determined whether the signal level has changed from the high level to the low level.

In step ST2, if the change in the signal state corresponds to the state indicated by the symbol P in FIG. 4, the number of times of image formation is reset (ST3), and the time when an image formation command is issued again is set as a reference. The counting of the number of image formation is restarted (ST4, ST5).

It is monitored whether or not the counted number of times restarted coincides with the number of times of replacement (ST6). If the number of times coincides with the number of times of replacement, an alarm prompting replacement is issued (ST7).

According to this embodiment, since the temperature fuse 14 that can be blown by the ambient temperature is disposed near the fixing belt 2 serving as a heat source, it is almost directly affected by the ambient temperature. As a result, the fusing is accelerated, and it is possible to quickly determine that the coating unit has been newly replaced by shortening the time from the time of replacement to the time of fusing. As a result, it is possible to shorten the waiting time until the counting of the number of image formation is restarted, thereby improving the workability when performing image formation.

[0035]

According to the first and second aspects of the present invention,
A temperature fuse that can be blown at a predetermined ambient temperature is provided in the coating unit, and a newly replaced coating unit can be determined based on the form of a signal output by blowing the temperature fuse. This makes it possible to accurately determine the newly replaced dispensing unit, so that it is possible to make a distinction at the time of replacement simply by using the ambient temperature that is immediately affected when the fixing unit is equipped for replacement. It is possible to accurately determine the time of replacement and accurately determine the remaining amount of the release agent without using a proper replacement identification structure.

According to the third aspect of the present invention, since the temperature fuse is disposed at the outermost end within the range of the maximum sheet passing width in the coating unit, the influence of the ambient temperature can be obtained most efficiently. This makes it possible to increase the sensitivity of the temperature fuse.

According to the fourth and fifth aspects of the present invention, the control unit in which the temperature fuse is connected to the input side is provided with a determination circuit, and the number of times of image formation is determined based on a change in the state of the output signal from the temperature fuse. Since resetting and restarting the counting of the number of new image formations, it is possible to accurately grasp the replacement time based on the time of the new replacement, and to warn of the replacement time suitable for the actual release agent consumption state. Can be performed.

According to the sixth aspect of the present invention, the number of times of image formation can be accurately counted by accurately grasping the point of time when a new coating unit is replaced, so that it can be adapted to the actual consumption state of the release agent. Consumption management can be performed, and generation of an abnormal image due to a shortage of the release agent can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an example of an image forming apparatus to which a fixing device according to an example for describing an embodiment of the present invention is applied.

FIG. 2 is a schematic diagram for explaining the overall configuration of the fixing device shown in FIG.

FIG. 3 is a block diagram illustrating a configuration of a control unit including a circuit that determines a replacement time of a coating unit used in the fixing device illustrated in FIG. 2;

FIG. 4 is a timing chart for explaining a state change of an output signal of a temperature fuse used in the control unit shown in FIG. 3;

FIG. 5 is a flowchart for explaining the operation of the control unit shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing device 2 Fixing belt 3 Heating roller 4 Fixing roller 5 Pressure roller 12 Release roller application roller 13 Application unit 14 Temperature fuse 15 Discrimination circuit 16 Control unit 17 Alarm unit 18 Counter for counting the number of image formation

Continued on the front page (72) Inventor Hideo Furukawa 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Hiroshi Ogawa 1-3-6 Nakamagome, Ota-ku, Tokyo, Co., Ltd. F-term in Ricoh (reference) 2H027 DA12 DA45 GB03 HB02 HB16 2H033 AA36 BA11 BA32 BA38 BA45 CA07

Claims (6)

[Claims] A fixing member for fixing toner contained in an unfixed image carried on a recording medium, wherein the fixing member contacts and heats the toner, and a release agent is supplied to a surface of the fixing member. A fixing device, comprising: a possible and replaceable coating unit, wherein the coating unit is provided with a configuration for determining that a new replacement has been performed based on a state change caused by an ambient temperature. 2. The fixing device according to claim 1, wherein the coating unit is provided with a temperature fuse that can be blown by a predetermined ambient temperature, and the temperature fuse is included in a determination circuit of a newly replaced coating unit. And a configuration in which when the output signal of the determination circuit changes under a predetermined condition, it is determined that the application unit is newly replaced. 3. The fixing device according to claim 1, wherein the temperature fuse provided in the coating unit is disposed at an outermost end within a range of a maximum sheet passing width in the coating unit. Fixing device. 4. The fixing device according to claim 2, wherein the determination circuit is provided in a control unit, and the control unit includes:
The temperature fuse is connected to the input side, an alarm unit and an image forming frequency counting unit are connected to the output side, and when it is determined that the image fuse has been newly replaced by a change in the state of the output signal from the temperature fuse, the image forming frequency is counted. A fixing device characterized by resetting and restarting counting. 5. The fixing device according to claim 4, wherein the control unit checks a new replacement of the coating unit, and warns the replacement of the coating unit when the number of image formations reaches a predetermined value after the replacement of the new coating unit. A fixing device characterized by the above-mentioned. 6. An image forming apparatus using the fixing device according to claim 1. Description: