JP2024063932A - Image forming device - Google Patents

Abstract

[Problem] To prevent productivity from decreasing due to print sheets whose back sides have already been printed by inkjet. [Solution] An image forming apparatus 10 includes an inkjet print engine 10a. When a control unit 51 determines that print sheets 101, 102 are print sheets whose back sides have already been printed based on an image read from the back sides of the print sheets 101, 102 by a line sensor 31, the control unit 51 determines whether or not to print on the front sides of the print sheets 101, 102 based on user settings input by user operation or a print request, and when printing on the front sides of the print sheets 101, 102 is to be performed, the print settings are adjusted and printing on the front sides of the print sheets 101, 102 is performed by the print engine 10a and sheet conveying unit 10b. [Selected Figure] Figure 1

Description

The present invention relates to an image forming device.

In one image forming device, when a print sheet used for printing has been printed on the back side, (a) a thickness sensor measures the thickness of the print sheet and the thickness of the image printed on the back side, (b) based on the measured thickness, determines whether the image printed on the back side is an ink print image or a toner print image, and (c) if the image printed on the back side is an ink print image, ejects the print sheet without printing, and if the image printed on the back side is a toner print image, adjusts the print settings and prints using an electrophotographic method (see, for example, Patent Document 1).

JP 2006-84675 A

However, in the above-mentioned image forming device, if many print sheets with back sides printed by inkjet are set in the paper feed cassette, there are fewer print sheets available for printing, which results in a long printing time and low productivity.

The present invention has been made in consideration of the above problems, and aims to provide an image forming device that prevents reduced productivity caused by print sheets whose reverse sides have already been printed by inkjet.

The image forming apparatus according to the present invention includes an inkjet print engine, a sheet transport unit that transports a print sheet to the print engine, an optical sensor that reads an image on the back side of the print sheet, and a control unit that determines whether the print sheet is a print sheet whose back side has been printed based on the image read by the optical sensor on the back side of the print sheet. If the print sheet is a print sheet whose back side has been printed, the control unit (a) determines whether to print on the front side of the print sheet based on user settings input by user operation or a print request, and (b) when printing on the front side of the print sheet is to be performed, adjusts the print settings and performs printing on the front side of the print sheet by the print engine and the sheet transport unit.

The present invention provides an image forming apparatus that prevents reduced productivity caused by print sheets that have already been back-printed by inkjet.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a side view illustrating the mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the image forming apparatus shown in FIG. FIG. 3 is a block diagram showing the electrical configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a flow chart for explaining the operation of the image forming apparatus shown in FIGS.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a side view illustrating the mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. Figure 2 is a plan view of the image forming apparatus shown in Figure 1.

The image forming device 10 in this embodiment is a device such as a printer, copier, facsimile machine, or multifunction device, and in this embodiment is equipped with a line-type inkjet color printing mechanism.

The image forming device 10 shown in FIG. 1 includes a print engine 10a and a sheet conveying unit 10b. The print engine 10a physically prints the image to be printed on a print sheet (such as print paper). The sheet conveying unit 10b conveys the print sheet to the print engine 10a.

In this embodiment, the print engine 10a is an inkjet print engine and is equipped with line-type inkjet recording units 1a-1d corresponding to four ink colors: cyan, magenta, yellow, and black.

As shown in FIG. 2, in this embodiment, each of the inkjet recording units 1a, 1b, 1c, and 1d has multiple (three in this example) head units 11. These head units 11 are arranged along the main scanning direction and are detachable from the device body. Note that each of the inkjet recording units 1a, 1b, 1c, and 1d may have only one head unit 11.

In this embodiment, the sheet transport unit 10b includes a circular transport belt 2 that is disposed opposite the print engine 10a and transports the print sheet, a drive roller 3 and a driven roller 4 on which the transport belt 2 is suspended, an attraction roller 5 that nips the print sheet together with the transport belt 2, and a pair of discharge rollers 6.

The drive roller 3 and driven roller 4 rotate the conveyor belt 2. The suction roller 5 nips the print sheet conveyed from the paper feed cassettes 20-1 and 20-2 (described below), and the nipped print sheet is conveyed by the conveyor belt 2 to the printing positions of the inkjet recording units 1a to 1d in order, where images of each color are printed by the inkjet recording units 1a to 1d. After color printing is completed, the print sheet is discharged by the discharge roller pair 6 onto a discharge tray (not shown) or the like.

The sheet transport section 10b further includes multiple paper feed cassettes 20-1, 20-2. The paper feed cassettes 20-1, 20-2 store print sheets 101, 102, and the lift plates 21, 24 push the print sheets 101, 102 upward and bring them into contact with the pickup rollers 22, 25. The print sheets 101, 102 placed in the paper feed cassettes 20-1, 20-2 are picked up one by one from above by the pickup rollers 22, 25 and then transferred to the paper feed rollers 23, 26. The paper feed rollers 23, 26 transport the print sheets 101, 102, which have been fed from the paper feed cassettes 20-1, 20-2 by the pickup rollers 22, 25, onto the transport path one by one.

The transport roller 27 is a transport roller on a transport path common to the print sheets 101 and 102 transported from the paper feed cassettes 20-1 and 20-2.

The registration rollers 28 temporarily stop the print sheets 101, 102 being conveyed and convey the print sheets 101, 102 to the print engine 10a at the secondary feed timing. The secondary feed timing is specified by the control unit 51, which will be described later, so that an image is formed at a specified position on the print sheets 101, 102.

Furthermore, the image forming device 10 is equipped with a line sensor 31.

The line sensor 31 is an optical sensor that reads an image of the back surface (the surface opposite the printed surface) of the print sheet being transported in the sheet transport section 10b. For example, the line sensor 31 is a CIS (Contact Image Sensor).

Figure 3 is a block diagram showing the electrical configuration of an image forming apparatus 10 according to an embodiment of the present invention. As shown in Figure 3, the image forming apparatus 10 includes an image output unit 41 having a mechanical configuration as shown in Figures 1 and 2, as well as an operation panel 42, a storage device 43, and an arithmetic processing unit 44. The image output unit 41 includes the line sensor 31 described above.

The operation panel 42 is disposed on the surface of the housing of the image forming device 10 and includes a display device such as a liquid crystal display and an input device such as hard keys and a touch panel, and displays various messages to the user on the display device and detects user operations on the input device.

The storage device 43 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 device 10.

The arithmetic processing device 44 includes a computer that operates according to a program, an ASIC (Application Specific Integrated Circuit) that executes a specific operation, and the like, and operates as various processing units. The computer includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and the like, and operates as various processing units (together with the ASIC if necessary) by loading programs stored in the ROM, storage device 43, etc., into the RAM and executing them on the CPU.

Here, the calculation processing device 44 operates as a control unit 51 and an image processing unit 52.

The control unit 51 controls the image output unit 41 to execute a print job requested by the user. In this embodiment, the control unit 51 causes the image processing unit 52 to execute a predetermined image processing, and controls the head unit 11 to eject ink to form a print image on the print sheets 101, 102. The image processing unit 52 executes predetermined image processing such as RIP (Raster Image Processing), color conversion, and halftoning on the image data of the image to be printed on the print sheets 101, 102.

In particular, the control unit 51 determines whether the print sheets 101, 102 are print sheets whose back sides have been printed, based on the image read by the line sensor 31 on the back sides of the print sheets 101, 102. If the print sheets 101, 102 are print sheets whose back sides have been printed, the control unit 51 (a) determines whether to print on the front sides of the print sheets 101, 102, based on user settings input by user operation or print request, and (b) when printing on the front sides of the print sheets 101, 102, adjusts the print settings and prints on the front sides of the print sheets 101, 102 using the print engine 10a and sheet conveying unit 10b.

In this embodiment, the above-mentioned print settings include setting the ink ejection amount in the print engine 10a and the conveying speed of the print sheets 101, 102 in the sheet conveying unit 10b. When printing on the front side of the print sheets 101, 102, the control unit 51 reduces the ink ejection amount from the default value and also reduces the conveying speed from the default value, and executes printing on the front side of the print sheets 101, 102 in the print engine 10a and the sheet conveying unit 10b.

The control unit 51 may also specify the print rate of the above-mentioned read image, and determine the amount of adjustment of the above-mentioned print settings according to the specified print rate. In that case, for example, the control unit 51 reduces the ink ejection amount and the conveying speed as the print rate increases.

The control unit 51 may also specify the width (area) of the overlapping portion between the above-mentioned read image and the image to be printed on the front surface of the print sheets 101 and 102, and determine the amount of adjustment of the above-mentioned print settings according to the specified width. In that case, for example, the control unit 51 may reduce the ink ejection amount and the transport speed as the width increases.

Next, the operation of the image forming device 10 according to this embodiment will be described. FIG. 4 is a flowchart illustrating the operation of the image forming device 10 shown in FIGS. 1 to 3.

When a print request is received from a host device by a communication device (not shown) or a print request is received by the operation panel 42, the control unit 51 executes the necessary image processing in the image processing unit 52 and controls the sheet conveying unit 10b to start conveying the print sheets 101 and 102 (step S1). When the print sheets 101 and 102 pass the installation position of the line sensor 31, the line sensor 31 outputs the back side image (image data) of the print sheets 101 and 102.

Then, the control unit 51 acquires the back side images (image data) of the print sheets 101 and 102 from the line sensor 31, and determines whether the print sheets 101 and 102 are print sheets whose back sides have been printed based on the back side images (step S2).

If the print sheets 101 and 102 are not print sheets with back side printing, the control unit 51 continues transporting the print sheets 101 and 102 to the print engine 10a, and causes the print engine 10a and the sheet transport unit 10b to print on the print sheets 101 and 102 with default print settings (step S3).

On the other hand, if the print sheets 101, 102 are print sheets that have already been printed on the back side, the control unit 51 determines whether or not to perform printing on the front side of the print sheets 101, 102 based on the user settings input by user operation or a print request (step S4).

When it is determined that printing should be performed on the front side of the print sheets 101, 102, the control unit 51 adjusts the print settings as described above (step S5), continues transporting the print sheets 101, 102 to the print engine 10a, and causes the print engine 10a and the sheet transport unit 10b to print on the front side of the print sheets 101, 102 with the adjusted print settings (step S6). Then, after printing on the print sheets 101, 102 is completed, the control unit 51 returns the print settings to the default values (step S7).

On the other hand, if it is determined that printing should not be performed on the front side of the print sheets 101, 102, the control unit 51 stops transporting the print sheets 101, 102 to the print engine 10a and ejects the print sheets 101, 102 onto the purge tray 10c (step S8).

In this way, the images specified by the user are printed one page at a time.

As described above, according to the embodiment, the image forming apparatus 10 includes an inkjet print engine 10a. The control unit 51 determines whether the print sheets 101 and 102 are print sheets whose back sides have been printed, based on the read image of the back sides of the print sheets 101 and 102 by the line sensor 31. If the print sheets 101 and 102 are print sheets whose back sides have been printed, the control unit 51 (a) determines whether to print on the front sides of the print sheets 101 and 102, based on the user settings input by user operation or print request, and (b) when printing on the front sides of the print sheets 101 and 102, adjusts the print settings and prints on the front sides of the print sheets 101 and 102 with the print engine 10a and the sheet conveying unit 10b.

As a result, if a user wants to prioritize productivity over print image quality, printing will be performed based on the user settings even if the print sheet has already been printed on the back side by inkjet, preventing a decrease in productivity due to print sheets that have already been printed on the back side by inkjet.

It should be noted that various changes and modifications to the above-described embodiments 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 its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

For example, in the above embodiment, the image forming apparatus 10 further includes a thickness sensor that measures the thickness of the backside print image of the print sheet 101, and when the print sheet 101 is a print sheet with backside printing, the control unit 51 (a) determines whether the print sheet 101 is a print sheet with backside printing by an inkjet method or a print sheet with backside printing by an electrophotographic method based on the thickness, and (b) may change the adjustment amount of the print setting depending on whether the print sheet 101 is a print sheet with backside printing by an inkjet method or a print sheet with backside printing by an electrophotographic method. In that case, when the print sheet 101 is a print sheet with backside printing by an inkjet method, the transport speed is set lower and the ink ejection amount is set smaller than when the print sheet 101 is a print sheet with backside printing by an electrophotographic method.

The present invention can be applied to, for example, inkjet type image forming devices.

10 Image forming apparatus 10a Print engine 10b Sheet conveying unit 31 Line sensor (an example of an optical sensor)
51 Control unit

Claims (5)

Inkjet print engine,
a sheet conveying section for conveying a print sheet to the print engine;
an optical sensor for reading an image on the back side of the print sheet;
a control unit that determines whether the print sheet is a print sheet whose back side has been printed based on an image read by the optical sensor on the back side of the print sheet,
When the print sheet is a print sheet whose back side has been printed, (a) based on a user setting input by a user operation or a print request, the control unit determines whether or not to execute printing on the front side of the print sheet, and (b) when executing printing on the front side of the print sheet, adjusts the print setting and executes printing on the front side of the print sheet by the print engine and the sheet conveying unit;
An image forming apparatus comprising: the print settings include settings of an ink ejection amount in the print engine and a transport speed of the print sheet in the sheet transport unit;
when printing on the front side of the print sheet, the control unit reduces the ink ejection amount from a default value and also reduces the conveying speed from a default value, and executes printing on the front side of the print sheet by the print engine and the sheet conveying unit;
2. The image forming apparatus according to claim 1, The image forming device according to claim 1, characterized in that the control unit specifies the print ratio of the read image and determines the amount of adjustment of the print settings according to the specified print ratio. The image forming device according to claim 1, characterized in that the control unit determines the width of the overlapping area between the scanned image and the image to be printed on the front side of the print sheet, and determines the amount of adjustment of the print settings according to the determined width. a thickness sensor for measuring a thickness of the backside print image of the print sheet;
The image forming apparatus according to any one of claims 1 to 4, characterized in that, when the print sheet is a print sheet with back printing, the control unit (a) determines based on the thickness whether the print sheet is a print sheet with back printing by an inkjet method or a print sheet with back printing by an electrophotographic method, and (b) changes the adjustment amount of the print setting depending on whether the print sheet is a print sheet with back printing by an inkjet method or a print sheet with back printing by an electrophotographic method.

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