Image forming apparatus

Abstract

To obtain an image forming apparatus which reduces the possibility that a print sheet is damaged by heat coming from a heater of a dryer.SOLUTION: A drier 7 dries, by a heater 7a, an ink on a print sheet after printing. A controller 75 is configured to: (a) turn off the heater 7a of the drier 7 and execute test printing when jamming of the print sheet at the heater 7a is detected, and the jamming is eliminated, and then the test printing is executed; and (b) turn on the heater 7a of the drier 7 and restarts the printing when the test printing is successful.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] When a jam occurs in a certain image forming apparatus and printing stops, when the jam is cleared, one sheet is conveyed to determine whether the sheet is conveyed normally. If the sheet is conveyed normally, printing is resumed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A certain inkjet type image forming apparatus includes a dryer, and heats and dries a printed sheet after printing with a heater of the dryer. When increasing productivity (printing speed), since the time for the printed sheet to pass through the dryer becomes shorter, it is necessary to dry the printed sheet at a high temperature. Therefore, when a jam occurs in the printed sheet with the heater of the dryer, the printed sheet may stagnate at that position and the printed sheet may be damaged by the heat from the heater.

[0005] Even when performing a test print after jam clearance as described above, there is a possibility that a jam may occur, and there is a possibility that the printed sheet may be damaged by the heat from the heater.

[0006] The present invention has been made in view of the above problems, and an object thereof is to obtain an image forming apparatus that reduces the possibility of damage to a printed sheet by the heat from the heater of the dryer.

Means for Solving the Problems

[0007] The image forming apparatus according to the present invention includes a recording head that discharges ink to form an image to be printed on a print sheet, a sheet conveyance unit that conveys the print sheet, a heater, and a dryer that dries the ink on the print sheet on which the image is formed by the recording head using the heater, and a controller that controls the sheet conveyance unit and the recording head to execute printing of the image at a predetermined print speed and controls the heater of the dryer. Then, when (a) a jam of the print sheet by the heater is detected and a test print is executed after the jam is resolved, the controller turns off the heater of the dryer and executes the test print, and when (b) the test print is successful, the controller turns on the heater of the dryer and resumes the printing.

Advantages of the Invention

[0008] According to the present invention, an image forming apparatus can be obtained that reduces the possibility of damage to the print sheet by heat from the heater of the dryer.

[0009] The above or other objects, features, and advantages of the present invention will become more apparent from the following detailed description together with the accompanying drawings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] Embodiment 1.

[0013] FIG. 1 is a diagram showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 10 shown in FIG. 1 is an apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine, and in this embodiment, it includes a line head type inkjet color printing mechanism.

[0014] The image forming apparatus 10 shown in FIG. 1 includes a print engine 10a and a sheet conveyance unit 10b. The print engine 10a attaches ink to the print sheet 101 and physically prints the image to be printed on the print sheet 101. For example, an ink cartridge is detachable from the print engine 10a, and the print engine 10a performs printing using the ink supplied from the ink cartridge. Also, the sheet conveyance unit 10b is a conveyance device that conveys the print sheet 101 before printing to the print engine 10a and conveys the print sheet 101 after printing to the discharge tray 10c via the dryer 7.

[0015] In this embodiment, the print engine 10a includes line head type recording heads 1a to 1d corresponding to four ink colors: cyan, magenta, yellow, and black. The recording heads 1a to 1d eject the ink of their respective ink colors through nozzles to form the image to be printed on the print sheet 101. In the case of a monochrome image forming apparatus, there is one recording head.

[0016] In this embodiment, the sheet conveyance unit 10b includes an annular conveyance belt 2 that is disposed opposite to the print engine 10a and conveys the print sheet 101, a drive roller 3, a driven roller 4, and a tension roller 4a that suspend the conveyance belt 2, a suction roller 5 that nips the print sheet 101 together with the conveyance belt 2, a subsequent-stage conveyance belt 6, and a dryer 7.

[0017] The drive roller 3, the driven roller 4, and the tension roller 4a circulate the conveyance belt 2. Then, the suction roller 5 nips the print sheet 101 conveyed from the paper feed cassette 20 described later. The nipped print sheet 101 is sequentially conveyed by the conveyance belt 2 to the print positions of the recording heads 1a to 1d, and images of respective colors are printed by the recording heads 1a to 1d. At this time, the passage of the print sheet 101 is detected by the sheet sensor 2a, and the current position of the print sheet 101 on the conveyance path is specified based on the detection timing, whereby an image is printed at an appropriate position on the print sheet 101. Then, the print sheet 101 after the printing is completed is discharged to the discharge tray 10c or the like by the subsequent-stage conveyance belt 6. At this time, the dryer 7 dries the print sheet 101 on which the ink has been ejected.

[0018] Specifically, the dryer 7 includes a heater 7a, and the heater 7a dries the ink in the print sheet on which the image has been formed by the recording heads 1a to 1d.

[0019] Further, the sheet suction unit 9 is disposed along the conveyance path of the sheet. A negative pressure is applied to the sheet suction unit 9, whereby the print sheet 101 is adsorbed to the conveyance belt 2 through the sheet suction holes.

[0020] Furthermore, the sheet conveyance unit 10b includes a paper feed cassette 20 as a paper feed source. The paper feed cassette 20 stores the print sheet 101, and pushes up the print sheet 101 upward with a lift plate 21 to abut against a pickup roller 22. The print sheets 101 placed on the paper feed cassette 20 are picked up one by one from above by the pickup roller 22 and fed to a paper feed roller 23. The paper feed roller 23 conveys the print sheets 101 fed from the paper feed cassette 20 by the pickup roller 22 onto the conveyance path one by one.

[0021] The conveyance roller 27 conveys the print sheet 101 on a predetermined conveyance path. When the conveyed print sheet 101 is detected by a registration sensor 28a, the registration roller 28 temporarily stops the print sheet 101 and conveys the print sheet 101 to the print engine 10a (specifically, to the nip position between the suction roller 5 and the conveyance belt 2) at the secondary paper feed timing. The secondary paper feed timing is specified by a controller 75 so that an image is formed at a specified position on the print sheet 101.

[0022] FIG. 2 is a block diagram showing the electrical configuration of the image forming apparatus 10 according to the embodiment of the present invention. As shown in FIG. 2, the image forming apparatus 10 includes, in addition to a printing apparatus 71 having a mechanical configuration as shown in FIG. 1, an operation panel 72, a storage device 73, an image reading device 74, and a controller 75.

[0023] The operation panel 72 is disposed on the surface of the housing of the image forming apparatus 10, and includes a display device 72a such as a liquid crystal display and an input device 72b such as a hard key and a touch panel. The display device 72a displays various messages to the user, and the input device 72b receives user operations.

[0024] The storage device 73 is a non-volatile storage device (such as a flash memory or a hard disk drive) that stores data, programs, etc. necessary for controlling the image forming apparatus 10.

[0025] The image reading device 74 includes a platen glass and an automatic document feeder, optically reads the image of a document placed on the platen glass or a document conveyed by the automatic document feeder, and generates image data of the image.

[0026] The controller 75 includes a computer that operates according to a program, an ASIC (Application Specific Integrated Circuit) that executes a predetermined operation, etc., and operates as various processing units. The computer includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., loads the program stored in the ROM, the storage device 73, etc. into the RAM, and executes various processes by executing with the CPU.

[0027] Specifically, the controller 75 controls the sheet conveyance unit 10b and the recording heads 1a to 1d to execute printing of an image at a predetermined printing speed, and controls the heater 7a of the dryer 7.

[0028] In particular, when (a) a jam of the printed sheet 101 at the heater 7a is detected and a test print is executed after the jam is resolved, the controller 75 turns off the heater 7a of the dryer 7 and executes the test print, and (b) when the test print is successful, turns on the heater 7a of the dryer 7 and resumes printing. When the test print fails, the controller 75 performs predetermined error processing (notification to the user or service person (service call), etc.) without resuming printing.

[0029] Note that the sheet conveyance unit 10b is provided with a plurality of conveyance sensors that detect the passage of the printed sheet 101 along the conveyance path, and the controller 75 detects a jam of the printed sheet 101 based on the output signals of the conveyance sensors and identifies the location where the jam has occurred. Also, at the time of test printing, the printing speed may be set lower than the above-described predetermined printing speed.

[0030] Next, the operation of the image forming apparatus 10 according to Embodiment 1 will be described. FIG. 3 is a flowchart for explaining the operation of the image forming apparatus 10 according to Embodiment 1.

[0031] Based on the output signals of the conveyance sensors, the controller 75 detects a jam of the printed sheet 101 at the heater 7a (step S1). When jam release by the user is detected (step S2), with the heater 7a turned off (step S3), the controller 75 controls the sheet conveyance unit 10b and the recording heads 1a to 1d to perform a test print on one printed sheet 101 (step S4).

[0032] During test printing, the controller 75 determines whether the printed sheet 101 has been printed and normally discharged to the discharge tray 10c (step S5).

[0033] When the printed sheet 101 of the test print has been normally discharged to the discharge tray 10c (that is, when the test print has been successful), the controller 75 turns on the heater 7a (step S6) and resumes printing for the subsequent printed sheets 101 (step S7).

[0034] On the other hand, when the printed sheet 101 of the test print has not been normally discharged to the discharge tray 10c (that is, when the test print has failed), error processing is performed without resuming printing (step S8).

[0035] As described above, according to the first embodiment, when the controller 75 detects a jam of the print sheet in the heater 7a and executes a test print after the jam is resolved, the controller 75 turns off the heater 7a of the dryer 7 and executes the test print. (b) If the test print is successful, the controller 75 turns on the heater 7a of the dryer 7 and resumes printing.

[0036] As a result, even if a jam occurs during the test print, the print sheet 101 will not be thermally damaged, so the possibility of the print sheet being damaged by the heat from the heater 7a of the dryer 7 is reduced. In addition, since the possibility of another jam occurring when printing resumes is low, the possibility of the print sheet being damaged by the heat from the heater 7a of the dryer 7 when a jam occurs after printing resumes is reduced.

[0037] Second Embodiment.

[0038] In the second embodiment, when the controller 75 turns on the heater 7a of the dryer 7 and resumes printing, the controller 75 resumes printing at a print speed lower than the above-described predetermined print speed, and gradually increases the print speed of the resumed print to the predetermined print speed (for each predetermined number of sheets).

[0039] Further, when gradually increasing the print speed of the resumed print to the predetermined print speed, if a jam in the heater 7a is detected again before the print speed of the resumed print reaches the predetermined print speed, the controller 75 resumes printing at a print speed lower than the print speed when the jam was detected after the jam is resolved.

[0040] Next, the operation of the image forming apparatus 10 according to the second embodiment will be described. FIG. 4 is a flowchart for explaining the operation of the image forming apparatus 10 according to the second embodiment.

[0041] Based on the output signal of the conveyance sensor, the controller 75 detects a jam of the printed sheet 101 at the heater 7a (step S21). When jam removal by the user is detected (step S22), similar to Embodiment 1, with the heater 7a turned off (step S23), the controller 75 controls the sheet conveyance unit 10b and the recording heads 1a - 1d to perform a test print on one printed sheet 101 (step S24).

[0042] Also, similar to Embodiment 1, during the test print, the controller 75 determines whether the printed sheet 101 is printed and normally discharged to the discharge tray 10c (step S25).

[0043] When the printed sheet 101 of the test print is normally discharged to the discharge tray 10c (that is, when the test print is successful), in Embodiment 2, the controller 75 turns on the heater 7a (step S26) and performs printing on a predetermined number (for example, 10 sheets) of subsequent printed sheets 101 at the first print speed (step S27).

[0044] During this printing, the controller 75 determines whether the printed sheet 101 is printed and normally discharged to the discharge tray 10c (step S28).

[0045] When the printed sheet 101 of this printing is normally discharged to the discharge tray 10c (that is, when the printing at the first print speed is successful), the controller 75 performs printing on a predetermined number (for example, 10 sheets) of subsequent printed sheets 101 at a second print speed higher than the first print speed (step S29).

[0046] During this printing, the controller 75 determines whether the printed sheet 101 is printed and normally discharged to the discharge tray 10c (step S30).

[0047] When the printed sheet 101 of this print is normally discharged to the discharge tray 10c (that is, when the printing at the second printing speed is successful), the controller 75 performs printing on the subsequent printed sheets 101 at a third printing speed higher than the second printing speed (the predetermined printing speed set above) (step S31).

[0048] On the other hand, when the printed sheet 101 of this print is not normally discharged to the discharge tray 10c (that is, when the printing at the second printing speed fails), the controller 75 performs printing on the subsequent printed sheets 101 at the first printing speed (step S32).

[0049] Here, for example, the first printing speed is 50 ppm, the second printing speed is 100 ppm, and the third printing speed is 150 ppm.

[0050] Also, when it is determined that the printing has failed in step S25 or step S28, the controller 75 performs error processing (step S33). When it is determined that the printing has failed in step S28, the controller 75 may attempt to print on the subsequent printed sheets 101 at a printing speed lower than the first printing speed.

[0051] Note that since the other configurations and operations of the image forming apparatus according to the second embodiment are the same as those of the embodiment, the description thereof is omitted.

[0052] Note that various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing the intended advantages. That is, it is intended that such changes and modifications be included within the scope of the claims.

Industrial Applicability

[0053] The present invention is applicable to, for example, an inkjet type image forming apparatus.

Explanation of Signs

[0054] 1a to 1d Recording head 7 Dryer 7a Heater 10 Image forming apparatus 10b Sheet conveyance unit 75 Controller

Claims

1. A recording head that ejects ink to form an image to be printed on a print sheet, A sheet conveyance unit that conveys the print sheet, A dryer that includes a heater and dries the ink on the print sheet on which the image has been formed by the recording head using the heater, A controller that controls the sheet conveyance unit and the recording head to execute printing of the image at a predetermined print speed and controls the heater of the dryer, When the controller detects a jam of the print sheet by the heater and executes a test print after the jam is resolved, the controller turns off the heater of the dryer and executes the test print. When the test print is successful, the controller turns on the heater of the dryer and resumes the printing, An image forming apparatus characterized by the above.

2. When the controller turns on the heater of the dryer and resumes the printing, the controller resumes the printing at a print speed lower than the predetermined print speed and gradually increases the print speed of the printing after resumption to the predetermined print speed. The image forming apparatus according to Claim 1, characterized by this.

3. When the controller gradually increases the print speed of the printing after resumption to the predetermined print speed, if a jam by the heater is detected again before the print speed of the printing after resumption reaches the predetermined print speed, after the jam is resolved, the controller resumes the printing at a print speed lower than the print speed when the jam was detected. The image forming apparatus according to Claim 2, characterized by this.

4. When the controller fails the test print, the controller performs predetermined error processing without resuming the printing. The image forming apparatus according to Claim 1, characterized by this.

Images