JP2020112669A - Image forming apparatus - Google Patents

Abstract

To increase productivity when not adding liquid to a recording material.SOLUTION: An image forming apparatus comprises liquid addition means 201 that adds a liquid 1 to a recording material on which an image is formed. The image forming apparatus has necessity determination means that determines whether to add the liquid to the recording material; and conveyance path switching means 11 that switches a conveyance path for the recording material such that when the necessity determination means determines to add the liquid, the apparatus conveys the recording material by using a first conveyance path A passing through the liquid addition means, and when necessity determination means determines not to add the liquid, the apparatus conveys the recording material by using a second conveyance path B not passing through the liquid addition means.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus.

Conventionally, there is known an image forming apparatus including a liquid applying unit that applies a liquid to a recording material on which an image is formed.

For example, Patent Document 1 discloses an image forming apparatus that feeds a fed sheet (recording material) to a fixing liquid applying device (liquid applying unit) to which the fixing liquid is applied, and then forms an image on the sheet. It is disclosed. This image forming apparatus includes a switching unit that controls a fixing liquid application device that applies a fixing liquid to a sheet by an ink jet method and switches whether to apply the fixing liquid to the sheet.

According to the conventional image forming apparatus, the liquid is not applied to the recording material, whether the liquid is applied to the recording material or the liquid is not applied to the recording material. Even if it can be omitted), productivity cannot be improved.

In order to solve the above-described problems, the present invention is an image forming apparatus including a liquid applying unit that applies a liquid to a recording material on which an image is formed, and whether the liquid is applied to the recording material. When it is determined that the liquid is to be applied by the necessity determination unit that determines whether or not the recording material is applied, the recording material is transferred using the first transfer path that passes through the liquid application unit, When the denial determination means determines that the liquid is not applied, the transport path switching is performed to switch the transport path of the recording material so that the recording material is transported using the second transport path that does not pass through the liquid deposition means. And means.

According to the present invention, productivity can be improved when a liquid is not applied to a recording material.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 3 is a schematic configuration diagram of a coating liquid application device in the image forming apparatus. FIG. 3 is a block diagram relating to transport path switching control according to the embodiment. 3 is a flowchart showing a flow of transport path switching control according to the embodiment.

An embodiment in which the image forming apparatus according to the present invention is applied to an electrophotographic image forming apparatus will be described below.
In the present embodiment, an electrophotographic image forming apparatus will be described as an example, but an image forming apparatus of another type such as an inkjet type may be used.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to this embodiment.
Reference numerals “Y”, “C”, “M”, and “K” in the drawing indicate members for the respective colors of yellow, cyan, magenta, and black. Further, the conveyance path of the print medium P such as paper as a recording material is indicated by a broken line.

The printing medium P fed from the sheet feeding device 300 is conveyed to the coating liquid application device 200, and the coating liquid application unit 201, which is a liquid application device, applies the liquid coating liquid to the surface of the printing medium P by application. It The liquid application method is not limited to application, and may be another method. The applied coating liquid is dried by heat in the drying unit 202 and then conveyed to the image forming apparatus main body 100.

The image forming apparatus main body 100 includes four toner image forming units 101Y, 101M, 101C, and 101K for generating toner images of yellow, magenta, cyan, and black, respectively. These toner image forming units 101Y, 101M, 101C, and 101K use Y, C, M, and K toners of different colors as image forming substances, but have the same configuration except that, The symbols Y, C, M, and K indicating the colors of the toners used will be omitted as appropriate in the description.

The image forming apparatus main body 100 includes an intermediate transfer belt 102, which is an intermediate transfer member, below the four toner image forming units 101. The intermediate transfer unit 103, which is a transfer unit, moves the intermediate transfer belt 102 endlessly while stretching the intermediate transfer belt 102 with a plurality of stretching rollers. Below the intermediate transfer unit 103, a fixing device 104 as a fixing unit is provided. The print medium P having the toner image fixed by the fixing device 104 is finally conveyed to the paper discharge tray 105.

FIG. 2 is a schematic configuration diagram of the coating liquid coating apparatus 200 in this embodiment.
Depending on the type of print medium, it may not be possible to form an image because the specified fixing strength cannot be obtained, or the image formation speed may be slowed down to allow the fixing process to take longer, and the fixing process may be performed with more heat. There are cases where a predetermined fixing strength is obtained by carrying out. In the present embodiment, in order to be compatible with such a print medium, an image is printed with respect to the print medium before the fixing process (the print medium before the image is formed (before the image is transferred in the present embodiment)). A predetermined fixing strength is obtained by applying a coating liquid for increasing the fixing strength of (toner).

The coating liquid coating unit 201 provided in the coating liquid coating apparatus 200 of the present embodiment pumps up the coating liquid 1 contained in the tank by the squeeze roller 2 which is rotationally driven, and supplies it onto the coating roller 3. The print medium P conveyed through the first conveyance path A passes through the nip portion between the application roller 3 and the pressure roller 4, and at that time, the coating liquid 1 on the application roller 3 is applied to the print medium P. (Granted).

Further, in the present embodiment, a viscosity changing unit that changes the viscosity of the coating liquid 1 is provided. If the viscosity of the coating liquid 1 is increased, the coating amount of the coating liquid 1 on the printing medium P can be increased, and if the viscosity of the coating liquid 1 is lowered, the coating amount of the coating liquid 1 on the printing medium P is decreased. be able to. Therefore, the coating amount of the coating liquid 1 on the printing medium P can be changed by changing the viscosity of the coating liquid 1 by the viscosity changing unit. For example, for the printing medium P having a small surface roughness, the viscosity of the coating liquid 1 is increased by the viscosity changing means so that the coating amount of the coating liquid 1 on the printing medium P is adjusted to be large. For the printing medium P having a large size, the viscosity of the coating liquid 1 is reduced by the viscosity changing means so that the coating amount of the coating liquid 1 on the printing medium P is adjusted to be small. As a result, almost the same amount of the coating liquid 1 can be applied to any printing medium P regardless of the difference in surface roughness.

The viscosity changing unit of the present embodiment is a temperature changing unit that changes the viscosity of the coating liquid 1 by changing the temperature of the coating liquid 1. However, other viscosity changing means such as a means for changing the solid content concentration of the coating liquid 1 may be used. In the case of the temperature changing means, the viscosity of the coating liquid 1 can be lowered by increasing the temperature of the coating liquid 1, and the viscosity of the coating liquid 1 can be increased by lowering the temperature of the coating liquid 1.

As shown in FIG. 2, the coating liquid application unit 201 of this embodiment includes a temperature sensor 6 for detecting the temperature of the coating liquid 1, a heater 8 as a heating unit for heating the coating liquid 1, and a surface of the print medium P. The temperature control unit 7 controls the heater 8 based on the roughness and the detection result of the temperature sensor 6. In the present embodiment, as shown in FIG. 1, the surface roughness of the print medium P is detected by the optical sensor 21 arranged upstream of the coating liquid application unit 201 in the recording material conveyance direction. Is not limited to this. For example, the surface roughness of the print medium P may be acquired from information input by a user operation (type information of the print medium P, etc.).

The temperature control unit 7 of the coating liquid application unit 201 in the present embodiment first determines the coating liquid application amount on the printing medium P based on the surface roughness of the printing medium P obtained from the detection result of the optical sensor 21. The target temperature at which the viscosity of the coating liquid 1 becomes an appropriate amount according to the roughness is determined. Then, when the temperature of the coating liquid 1 detected by the temperature sensor 6 is lower than the determined target temperature, the temperature control unit 7 heats the coating liquid 1 by the heater 8 to raise the temperature of the coating liquid 1. Let On the contrary, when the temperature of the coating liquid 1 detected by the temperature sensor 6 is higher than the determined target temperature, the heater 8 is stopped and the temperature of the coating liquid 1 is lowered. By performing such control, the temperature of the coating liquid 1 applied to the printing medium P is controlled to the target temperature, and the viscosity of the coating liquid 1 applied to the printing medium P is thereby adjusted to the target temperature. The viscosity is controlled so that the liquid application amount is an appropriate amount according to the surface roughness of the print medium P.

Here, depending on the type of print medium, there are some that can obtain sufficient fixing strength without applying the coating liquid 1. If the coating liquid 1 is applied to the printing medium P that does not require the coating liquid 1 as described above, the coating liquid 1 is wastefully consumed.

Therefore, in the coating liquid coating apparatus 200 of the present embodiment, as shown in FIG. 2, the first transport path A that passes through the coating liquid coating unit 201 as a liquid applying unit and the drying unit 202, and the coating liquid coating unit A second transport path B that does not pass through the unit 201 and the drying unit 202 is formed. Then, according to the type of the print medium P fed from the paper feeding device 300, the switching pawl 11 serving as a transporting path switching unit causes the print medium P fed from the paper feeding device 300 to move to the first transporting path. It is switched between sending to A and sending to the second transport path B.

FIG. 3 is a block diagram relating to the transport path switching control of this embodiment.
In the present embodiment, for a print medium to which the coating liquid 1 needs to be applied, the drive motor 11a of the switching claw 11 is controlled so as to be conveyed using the first conveying path A, and the coating liquid 1 needs to be applied. For the non-printing medium, the drive motor 11a of the switching claw 11 is controlled so that it is conveyed using the second conveyance path B. Whether or not the coating liquid 1 is applied to the print medium can be determined according to the type of print medium. In the present embodiment, it is determined whether or not the coating liquid 1 is applied according to the difference in surface roughness of the print medium and the difference in the thickness of the print medium. The necessity determination may be performed based on only the conditions, or the necessity determination may be performed under another condition, and the necessity determination condition for whether or not the coating liquid 1 is applied is appropriately set.

As the surface roughness of the print medium, the surface roughness detected by the optical sensor 21 described above is used. On the other hand, the thickness of the print medium can be detected using, for example, the paper thickness sensor 22 provided in the conveyance roller pair 301 provided in the paper feeding device 300. The paper thickness sensor 22 detects a displacement amount of the distance between the roller axes when the fed print medium is nipped by the pair of transport rollers 301, but other known paper thickness detecting means is used. Good. Further, the thickness of the print medium may be acquired from, for example, information input by a user operation (type information of the print medium P or the like).

FIG. 4 is a flowchart showing the flow of the transport path switching control of this embodiment.
Generally, a print medium P having a large surface roughness, such as an uneven paper such as Japanese paper, tends to have a low fixing strength of an image (toner). Therefore, the control unit 20 acquires the surface roughness of the print medium P obtained from the output signal from the optical sensor 21 (S1), and when it determines that the surface roughness exceeds a predetermined threshold value (S3). Yes), the drive motor 11a of the switching claw 11 is controlled to switch to the first transport path A (S5). As a result, with respect to the print medium P having such a large surface roughness, the coating liquid 1 is applied by the coating liquid application unit 201, dried by the drying unit 202, and then conveyed to the image forming apparatus main body 100.

Further, the thick print medium P tends to have low fixing strength of the image (toner). Therefore, the control unit 20 acquires the thickness of the print medium P obtained from the output signal from the paper thickness sensor 22 (S2), and when it determines that the thickness exceeds the predetermined threshold value (Yes in S4). ), and controls the drive motor 11a of the switching claw 11 to switch to the first transport path A (S5). As a result, the print medium P having such a thickness is conveyed by the conveyance rollers 12A, 13A, 14A of the first conveyance path A, the coating liquid 1 is applied by the coating liquid application unit 201, and dried by the drying unit 202. After that, it is conveyed to the image forming apparatus main body 100 by the common conveying rollers 15 and 16.

On the other hand, for the printing medium P having a small surface roughness and a small thickness, sufficient fixing strength can be obtained without applying the coating liquid 1. Therefore, when the surface roughness is less than or equal to the predetermined threshold value and the thickness is less than or equal to the predetermined threshold value (No in S3, No in S4), the control unit 20 controls the drive motor 11a of the switching claw 11. Then, it is switched to the second transport path B (S6). As a result, the print medium P that does not need to be coated with the coating liquid 1 is transported by the transport rollers 12B, 13B, 14B and the common transport rollers 15, 16 in the second transport path B, and the coating liquid coating unit 201 and the drying unit 202. The sheet is conveyed as it is to the image forming apparatus main body 100 without passing through.

According to the present embodiment, the coating liquid 1 is not applied to the printing medium that does not require the coating liquid 1, and wasteful consumption of the coating liquid 1 can be suppressed.

Further, for a print medium that does not require the application of the coating liquid 1, the coating liquid 1 is not applied, and thus the drying step is unnecessary. Therefore, the second transport path B through which the print medium that does not need to be coated with the coating liquid 1 is transported can have a shorter path length than the first transport path A that passes through the coating liquid coating unit 201 and the drying unit 202. .. Since the second conveyance path B of the present embodiment has a shorter path length than the first conveyance path A, it takes time to convey the fed print medium P to the image forming apparatus main body 100. It is possible to shorten the time, and it is possible to improve the productivity of a print medium that does not require the application of the coating liquid 1.

In this embodiment, the liquid such as the coating liquid 1 is applied to the recording material such as the print medium P before the image is formed, but the liquid is applied to the recording material. If so, the same applies to the case where the liquid is applied to the recording material after the image is formed.
In the present embodiment, the liquid (coating liquid 1) for the purpose of increasing the fixing strength of the image (toner) on the print medium P is applied to the recording material, but the liquid for other purposes is applied to the recording material. The same applies to those that do.

What has been described above is an example, and a unique effect is obtained for each of the following aspects [first aspect]
A first aspect is an image forming apparatus including a liquid applying unit (for example, a coating liquid applying unit 201) for applying a liquid (for example, a coating liquid 1) to a recording material (for example, a printing medium P) on which an image is formed, Necessity determination means (for example, control unit 20) for determining whether or not to apply the liquid to the recording material, and the liquid application means when the necessity determination means determines to apply the liquid When the recording material is conveyed by using the first conveying path A passing through, and the necessity determination unit determines that the liquid is not applied, the second conveying path B not passing through the liquid applying unit is used. The present invention is characterized by including a transport path switching unit (for example, switching claw 11) that switches the transport path of the recording material so as to transport the recording material.
In this aspect, it is determined whether or not the liquid is applied to the recording material, and the recording material that is determined not to be applied with the liquid is transported using the second transport path that does not pass through the liquid deposition means. The first transport path for transporting the recording material to which the liquid is applied has a long path length set due to restrictions such as the arrangement of the liquid applying means and the drying time of the applied liquid. Since the second transport path used for transport does not have such a restriction, it is easy to adopt a configuration that shortens the transport time of the recording material, for example, by setting the transport path length shorter than the first transport path. Therefore, according to this aspect, it is possible to perform the image formation on the recording material to which the liquid is not applied in a shorter time than the image formation to the recording material to which the liquid is applied. Productivity can be improved.

[Second mode]
In a second aspect, in the first aspect, the transport path length of the recording material transported using the second transport path is shorter than the transport path length of the recording material transported using the first transport path. Is characterized by.
According to this, since it is possible to shorten the transportation time of the recording material to which the liquid is not applied, the image formation on the recording material to which the liquid is not applied is performed in a shorter time than the image formation on the recording material to which the liquid is applied. Therefore, the productivity of the recording material to which the liquid is not applied can be improved.

[Third aspect]
A third aspect is characterized in that, in the first or second aspect, the necessity determination means determines whether or not to apply the liquid according to the type of the recording material.
According to this, it becomes possible to appropriately determine whether or not the application of the liquid is necessary.

[Fourth mode]
A fourth aspect is characterized in that, in the third aspect, the type of the recording material includes a difference in surface roughness of the recording material.
According to this, it is possible to relatively easily determine whether or not the application of the liquid is necessary.

[Fifth aspect]
A fifth aspect is characterized in that, in the third or fourth aspect, the type of the recording material includes a difference in thickness of the recording material.
According to this, it is possible to relatively easily determine whether or not the application of the liquid is necessary.

[Sixth mode]
In a sixth aspect, in any one of the first to fifth aspects, the recording material that has passed through the first transport path and the second transport path is transported to the same image forming unit (for example, the image forming apparatus main body 100). It is characterized by that.
According to this, in a configuration in which the liquid is applied to the recording material before the image is formed by the image forming unit, wasteful consumption of the liquid can be suppressed.

1: coating liquid 2: squeeze roller 3: coating roller 4: pressure roller 11: switching claw 11a: drive motor 20: control unit 21: optical sensor 22: paper thickness sensor 100: image forming apparatus main body 101: toner image forming unit 102: Intermediate transfer belt 104: Fixing device 105: Paper ejection tray 200: Coating liquid applying device 201: Coating liquid applying unit 202: Drying unit 300: Paper feeding device 301: Conveying roller pair A: First conveying path B: Second Transport path P: print medium

JP 2012-189639 A

Claims (6)

An image forming apparatus comprising a liquid applying unit for applying a liquid to a recording material on which an image is formed,
Necessity determination means for determining whether or not to apply the liquid to the recording material,
If the necessity determination unit determines to apply the liquid, the recording material is conveyed using the first conveyance path that passes through the liquid application unit, and the necessity determination unit determines that the liquid is not applied. In this case, the image forming method further includes a transport path switching unit that switches the transport path of the recording material so that the recording material is transported using a second transport path that does not pass through the liquid applying unit. apparatus. The image forming apparatus according to claim 1,
The image forming apparatus is characterized in that a conveyance path length of a recording material conveyed through the second conveyance path is shorter than a conveyance path length of a recording material conveyed through the first conveyance path. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the necessity determination unit determines whether to apply the liquid according to the type of the recording material. The image forming apparatus according to claim 3,
The image forming apparatus, wherein the type of the recording material includes a difference in surface roughness of the recording material. The image forming apparatus according to claim 3 or 4,
The image forming apparatus, wherein the type of the recording material includes a difference in thickness of the recording material. The image forming apparatus according to any one of claims 1 to 5,
The image forming apparatus, wherein the recording material that has passed through the first transport path and the second transport path is transported to the same image forming unit.

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