Image forming apparatus and image forming method

Abstract

To form each of a visible image and an invisible image without reducing adhesion amount of liquid.SOLUTION: An image forming apparatus includes: an image forming section including a liquid discharge head having a plurality of nozzles for discharging liquid to a medium; and a control section. The control section controls the image forming section so that the liquid discharge head discharges liquid that absorbs visible light and does not absorb invisible light to one surface of the medium so as to form a visible image and the liquid discharge head discharges liquid that absorbs invisible light to the other surface of the medium so as to form an invisible image.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image forming method. [Background technology]

[0002] Inkjet printers, used as image recording devices (also called image forming devices) such as printers, copiers, facsimiles, and plotters, record images by ejecting ink droplets from a recording head and landing them on paper. Ink is fixed in inkjet printers by evaporating into the air and penetrating into the recording paper. For this reason, when printing on both sides of a recording paper, the image on the back side may appear darker and more visible (this is called "show-through"), the ink itself may seep through to the front side, causing background smearing (this is called "strike-through"), or the recording paper may become wavy.

[0003] Patent Document 1 discloses a technology that utilizes show-through in inkjet printers that use CMYK inks, outputting input image information on one side of a recording sheet and outputting specific image information that is set separately from the input image information on the other side of the recording sheet.

[0004] In recent years, inkjet printers that use a special invisible IR (Infrared) ink (invisible ink) in addition to the three visible inks of CMY have also become known. Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, with a four-color inkjet printer that adds a spot color (IR) to the three colors of CMY, visible images including black are visibly printed with CMY inks, and invisible images are invisible printed with IR ink. Therefore, when visible printing using CMY inks and invisible printing using IR ink are performed on one side of a recording paper, the amount of ink adhered to one side increases by the amount of IR ink, exceeding the amount of ink that the recording paper can absorb, causing the recording paper to ripple or the inks to bleed, resulting in a decrease in image quality.

[0006] When performing visible printing using CMY inks and invisible printing using IR inks on one side of a recording paper, it is possible to avoid the above problem by reducing the amount of ink applied. However, reducing the amount of ink applied results in a problem of the printed image becoming faint.

[0007] The present invention has been made in view of the above, and has as its object to form both a visible image and an invisible image without reducing the amount of applied liquid. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image forming apparatus comprising an image forming unit including a liquid ejection head having a plurality of nozzles that eject liquid onto a medium, and a control unit, wherein the control unit controls the image forming unit so that the liquid ejection head ejects a liquid that absorbs visible light but does not absorb invisible light onto one side of the medium to form a visible image, and so that the liquid ejection head ejects a liquid that absorbs invisible light onto the other side of the medium to form an invisible image. [Effects of the Invention]

[0009] According to the present invention, it is possible to form both a visible image and an invisible image without reducing the amount of applied liquid. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view illustrating an example of an inkjet printer according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the mechanism of the inkjet printer. [Figure 3] FIG. 3 is a block diagram showing an outline of the control unit of the inkjet printer. [Figure 4] FIG. 4 is a diagram showing an example of connections between the external device connection unit and various imaging devices. [Figure 5] FIG. 5 is a flowchart showing the process flow of the double-sided printing operation. [Figure 6] FIG. 6 is a flowchart showing the flow of the IR printing designation process. [Figure 7] FIG. 7 is a diagram showing an example of the IR print setting screen. [Figure 8] FIG. 8 is a flowchart showing the flow of the IR print specification process performed by the host printer driver. [Figure 9] FIG. 9 is a diagram showing an example of the IR print setting screen. [Figure 10] FIG. 10 is a diagram showing an example of an IR stamp editing screen. [Figure 11] FIG. 11 is a flowchart showing the flow of the IR printing process. [Figure 12] FIG. 12 is a diagram showing an example of the IR print setting screen. [Figure 13] FIG. 13 is a diagram illustrating a specific example of invisible printing (IR printing). [Figure 14] FIG. 14 is a diagram showing an example of image formation by liquid ejection. [Figure 15] FIG. 15 is a diagram showing a specific example of editing processing in invisible printing (IR printing). [Figure 16] FIG. 16 is a diagram showing a specific example of editing processing in invisible printing (IR printing). [Figure 17] FIG. 17 is a diagram showing a specific example of editing processing in invisible printing (IR printing). DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus and an image forming method will be described in detail below with reference to the accompanying drawings. In this embodiment, an inkjet printer is used as the image forming apparatus.

[0012] FIG. 1 is a perspective view showing an example of an inkjet printer 50 according to an embodiment, and FIG. 2 is a cross-sectional view showing a mechanical portion of the inkjet printer 50. As shown in FIG.

[0013] First, the inkjet printer 50 will be briefly described.

[0014] The inkjet printer 50 of this embodiment is capable of double-sided printing, and is configured to output input image information (visible image information) on one side of the recording paper, and output specific image information (IR image information) set separately from the input image information on the other side of the recording paper.

[0015] Here, the control unit 50a (see FIG. 3) of the inkjet printer 50 according to this embodiment can output specific image information (IR image information) as a mirror image that is flipped left and right. Based on the settings in the printer driver 101 (see FIG. 3) of the host 100, the control unit 50a of the inkjet printer 50 according to this embodiment has a first output mode in which the output result of the specific image information (IR image information) is a mirror image that is flipped left and right, and a second output mode in which the output result of the specific image information (IR image information) is a normal image without flipping.

[0016] In this case, the control unit 50a of the inkjet printer 50 according to this embodiment preferably includes a means for selecting either the first output mode or the second output mode. Also, the control unit 50a of the inkjet printer 50 according to this embodiment preferably selects either the first output mode or the second output mode in response to externally supplied designation information.

[0017] According to the control unit 50a of the inkjet printer 50 of this embodiment, whether or not to make specific image information (IR image information) a mirror image that is flipped left and right can be determined based on the settings in the printer driver 101 of the host 100, allowing the user to create data without worrying about flipping.

[0018] Furthermore, when printing the same image information as specific image information (IR image information), the control unit 50a of the inkjet printer 50 according to this embodiment preferably has a means for pre-storing the specific image information (IR image information). Furthermore, the control unit 50a of the inkjet printer 50 according to this embodiment preferably inputs the specific image information (IR image information) from the host 100 side. Furthermore, the inkjet printer 50 according to this embodiment preferably has an interface for connecting to an imaging device. Note that the term "imaging device" is used to include all devices that handle images.

[0019] Furthermore, the control unit 50a of the inkjet printer 50 according to this embodiment can include a means for editing specific image information (IR image information). For example, the control unit 50a of the inkjet printer 50 according to this embodiment can adjust (or use image processing to adjust) the amount of ink when outputting specific image information (IR image information) set separately from the input image information on the other side of the recording paper. In this case, the control unit 50a of the inkjet printer 50 according to this embodiment can select whether or not to vary the amount of ink (or use image processing to adjust) when outputting specific image information (IR image information) set separately from the input image information on the other side of the recording paper.

[0020] Next, the configuration of the inkjet printer 50 will be described in detail with reference to FIGS.

[0021] As shown in FIGS. 1 and 2, an inkjet printer 50 includes a main body 1 and a print mechanism 2, which serves as an image forming unit and is comprised of a carriage 13 movable in the main scanning direction, a recording head 14 consisting of a liquid ejection head mounted on the carriage 13, and an ink cartridge 15 that supplies ink to the recording head 14. A paper feed cassette (or paper feed tray) 4, which serves as a paper feed means capable of holding a large number of sheets of recording paper 3, is removably attached to the front of the lower portion of the main body 1. The recording paper 3 is a medium. The inkjet printer 50 also includes a manual feed tray 5 that can be opened and closed at the front. The inkjet printer 50 takes in recording paper 3 fed from the paper feed cassette 4 or set in the manual feed tray 5, records the required image on the paper using the print mechanism 2, and then ejects the paper to a paper ejection tray 6 attached to the rear. The inkjet printer 50 also has an operation panel 8 on its front.

[0022] The printing mechanism 2 that constitutes the liquid ejection unit holds a carriage 13 slidably in the main scanning direction (the direction perpendicular to the paper surface in Figure 2) using a main guide rod 11 and a secondary guide rod 12 that are horizontally mounted on left and right side panels (not shown).

[0023] The inkjet printer 50 has a recording head 14, which consists of a liquid ejection head having nozzles that eject ink droplets of yellow (Y), cyan (C), magenta (M), and a special invisible color, attached to the underside of the carriage 13 with the ink droplet ejection direction facing downward.

[0024] Yellow (Y), cyan (C), and magenta (M) inks are liquids (also called visible liquids or visible inks) that absorb visible light but not invisible light (infrared). IR (Infrared) ink, a special invisible ink, is a liquid (also called invisible liquid) that cannot be seen under visible light (i.e., it transmits visible light) but absorbs infrared light when irradiated with infrared light, forming an invisible image that becomes visible. IR ink contains an infrared absorbing material that absorbs light in the near-infrared range of 700 nm to 1200 nm.

[0025] In the inkjet printer 50, ink tanks (ink cartridges) 15 for supplying ink of each color to the recording head 14 are replaceably mounted on the upper side of the carriage 13.

[0026] The inkjet printer 50 does not have an ink tank (ink cartridge) for supplying black (K) ink or a liquid ejection head with nozzles for ejecting black (K) ink droplets. The inkjet printer 50 forms black by mixing CMY colors. The reason for forming black by mixing CMY colors is that when black (K) ink is applied to one side (front side) of the recording paper 3, the IR ink is absorbed by the coloring material of the black (K) ink, making the invisible image formed in IR ink on the other side (back side) of the recording paper 3 invisible with an infrared camera, infrared reader, etc.

[0027] 1, the carriage 13 is connected to a timing belt 20 that is stretched between a drive pulley 18 rotated by a main scanning motor 17 and a driven pulley 19. The inkjet printer 50 controls the driving of the main scanning motor 17 to move the carriage 13 in the main scanning direction.

[0028] The liquid ejection head, which is the recording head 14, has a nozzle row made up of a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and is mounted with the ejection direction facing downward.

[0029] The recording head 14 may be a head in which a plurality of heads for ejecting ink droplets of each color are arranged in the main scanning direction, or a head having a single nozzle for ejecting ink droplets of each color. The recording head 14 may be one in which an electromechanical transducer such as a piezoelectric element displaces a diaphragm to change the volume of a liquid chamber, thereby pressurizing the ink and ejecting ink droplets; one in which a heating resistor disposed in the liquid chamber generates bubbles by film boiling to pressurize the ink in the liquid chamber, thereby ejecting ink droplets; or one in which an electrostatic force between a diaphragm forming the wall surface of the liquid chamber and an electrode facing the diaphragm is used to displace the diaphragm, thereby ejecting ink droplets.

[0030] A "liquid ejection head" is a functional component that ejects and sprays liquid from nozzles. The liquid to be ejected may have a viscosity and surface tension that allows it to be ejected from the head.

[0031] In addition, in the present application, the terms image formation, recording, printing, copying, printing, modeling, etc. are all synonymous.

[0032] Meanwhile, in order to transport the recording paper 3 in the sub-scanning direction toward the printing position (synonymous with the printing position) by the recording head 14, the inkjet printer 50 has a transport belt 23 stretched and disposed between a transport roller 21 and a transport driven roller 22, which transports the recording paper 3 by electrostatic attraction. As shown in Fig. 1, the inkjet printer 50 has a sub-scanning motor 25. The inkjet printer 50 transmits the rotation of the sub-scanning motor 25 to the transport roller 21 via a gear train (not shown), thereby rotating the transport roller 21 in the sub-scanning direction.

[0033] The inkjet printer 50 has an image receiving member 26 located opposite the recording head 14 across the conveyor belt 23. The inkjet printer 50 also has a leading edge roller 27 that determines the feed angle of the recording paper 3 pressed against the conveyor roller 21 via the conveyor belt 23.

[0034] On the other hand, in order to feed recording paper 3 from the paper feed cassette 4 onto the conveyor belt 23, the inkjet printer 50 is provided with a paper feed roller 31 and a friction pad 32 that separate and feed the recording paper 3 one sheet at a time, and a guide member 34 that guides the fed recording paper 3 to an intermediate roller 33 that is arranged in contact with the conveyor roller 21.

[0035] In addition, in order to feed the recording paper 3 from the manual feed tray 5 to the conveyor belt 23, the inkjet printer 50 is provided with a pickup roller 35 that picks up the recording paper 3 from the manual feed tray 5, a feed roller 36 that feeds the recording paper 3, a feed roller 37, and a guide member 38 that guides the recording paper 3 to the intermediate roller 33.

[0036] The inkjet printer 50 is provided with a guide member 41 for guiding the recording paper 3, a paper discharge roller 42 for sending the recording paper 3 to the paper discharge tray 6, and a paper discharge driven roller 43, in order to discharge the recording paper 3 to the paper discharge tray 6 after printing has been completed.

[0037] Furthermore, in order to eject the recording paper 3 after printing outside the device body 1 and then feed it again onto the conveyor belt 23 for double-sided printing, the inkjet printer 50 is provided with a guide member 45 that guides the recording paper 3 that has passed the printing position by the recording head 14 diagonally downward toward the space between the paper discharge tray 6 and the paper feed cassette 4. The inkjet printer 50 is provided with a swingable first branch claw 46 near the entrance between the guide member 45 and the guide member 41 on the paper discharge side to branch the discharge path of the recording paper 3.

[0038] In addition, the inkjet printer 50 is provided with a switchback roller 47 and a switchback driven roller 48 near the end of the guide member 45 to discharge the recording paper 3 toward the top surface of the paper feed cassette 4 outside the device main body 1 (this is the position where the paper waits for re-feeding, i.e., the double-sided printing paper standby position), and to feed the recording paper 3 back into the device main body 1. In the inkjet printer 50, the switchback roller 47 rotates forward when transporting the recording paper 3 in the discharge direction after printing on one side has been completed, and rotates reversely when re-feeding the recording paper 3, and stops at a predetermined timing to clamp the trailing end of the recording paper 3 in the discharge direction when discharging the recording paper 3.

[0039] Furthermore, inkjet printer 50 has a second branch claw 49 arranged to swing freely upstream of switchback roller 47 and switchback driven roller 48 in the paper discharge direction, which switches the transport path of recording paper 3 between a discharge path out of device main body 1 and a path for re-feeding recording paper 3 into device main body 1. In order to feed recording paper 3 sent into device main body 1 by the reverse rotation of switchback roller 47 to transport belt 23, inkjet printer 50 is provided with a guide member 51 that guides recording paper 3, a double-sided relay roller 52 and double-sided relay roller driven roller 53 that transport recording paper 3, and a transport roller driven roller 54 that follows transport roller 21 to feed recording paper 3 to intermediate roller 33.

[0040] Next, an overview of the control unit 50a of the inkjet printer 50 will be described.

[0041] Fig. 3 is a block diagram showing an overview of the control unit 50a of the inkjet printer 50. As shown in Fig. 3, the control unit 50a of the inkjet printer 50 includes a CPU (Central Processing Unit) 70, which is a microcomputer that controls the entire inkjet printer 50, a ROM (Read Only Memory) 71 that stores specific image information and necessary fixed information such as a control program, a RAM (Random Access Memory) 72 that is used as a working memory or the like, an image memory 73 that stores data obtained by processing input image information, a parallel input / output (PIO) port 74, an input buffer 75, a parallel input / output (PIO) port 76, a waveform generation circuit 77, a head drive circuit 78 and drivers 79, 80, 81, an external device connection unit 87 for connecting to an external device, and the like.

[0042] Here, the printer driver 101 of the host 100, which is also a data processing device, transfers image information (which becomes input image information on the recording device side) to be printed (recorded or copied is also used synonymously), information specifying double-sided printing, specific image information, etc. to the PIO port 74 via a cable or network. The control unit 50a of the inkjet printer 50 also sends required information to the host 100 side via the PIO port 74.

[0043] The control unit 50a of the inkjet printer 50 also receives various designation or selection information, such as information specifying an output mode from the operation panel 8 shown in FIG. 1, and signals from various sensors, such as a home position sensor that detects the home position (reference position) of the carriage 13, and transmits information, such as display information, to the operation panel 8 through the PIO port 74.

[0044] The waveform generating circuit 77 uses a D / A converter to convert voltage data provided by the CPU 70 into an analog signal, thereby generating and outputting a drive waveform having drive waveform parameters such as required pulse width, peak value, rise time constant, fall time constant, etc. The control unit 50a of the inkjet printer 50 can change the ink droplet ejection characteristics by changing the drive waveform parameters.

[0045] Based on various data and signals provided via the PIO port 76, the head drive circuit 78 applies drive waveforms from the waveform generation circuit 77 to actuator means (electromechanical conversion elements such as piezoelectric elements, electrothermal conversion elements such as heating resistors, diaphragms or opposing electrodes, etc.) corresponding to each nozzle of the recording head 14 in accordance with the input image information and specific image information.

[0046] Furthermore, the driver 79 drives and controls the main scanning motor 17 to scan the carriage 13 in the main scanning direction in accordance with drive data provided via the PIO port 76, and drives and controls the sub-scanning motor 25 to rotate the transport roller 21 in the paper transport direction (sub-scanning direction). The driver 80 also drives and controls a motor 82 that rotates the switchback roller 47, a solenoid 83 that swings the first branch claw 46, and a solenoid 84 that swings the second branch claw 49.

[0047] The external device connection unit 87 is an interface for connecting imaging devices. FIG. 4 shows an example of a connection between the external device connection unit 87 and various imaging devices. For example, as shown in FIG. 4, the external device connection unit 87 includes ports and slots that enable connection to various imaging devices. The external device connection unit 87 includes at least one of various ports, such as parallel, infrared, and USB ports used for connecting to a computer; LAN ports used for connecting to a network; infrared, USB, and IEEE1394 ports used for connecting to a digital camera; SCSI, USB, and parallel ports used for connecting to a scanner; serial and USB ports used for connecting to a tablet; serial and telephone lines used for connecting to telephones and fax machines; and IEEE1394 ports used for connecting to digital video devices, as well as dedicated slots for FDs, MOs, HDDs, memory cards, IC cards, and the like. While FIG. 3 illustrates a scanner 90 as an example of imaging devices, the imaging devices are not limited to these.

[0048] Next, the double-sided printing operation of the inkjet printer 50 will be described.

[0049] Here, Fig. 5 is a flowchart showing the process flow of the double-sided printing operation. As shown in Fig. 5, when double-sided printing is instructed, the control unit 50a of the inkjet printer 50 switches the first branch claw 46 to the double-sided printing side (step S1), switches the second branch claw 49 to the ejection side (step S2), and rotates the switchback roller 47 forward (in the direction to eject the paper out of the device) (step S3).

[0050] The control unit 50a of the inkjet printer 50 also drives the paper feed roller 31 to rotate and feed the recording paper 3 from the paper feed cassette 4, so that the recording paper 3 is sent onto the conveyor belt 23 of the conveyor roller 21, electrostatically attracted to the conveyor belt 23, and conveyed in the sub-scanning direction (step S4).The control unit 50a of the inkjet printer 50 then prints a desired image on the front (one side) of the recording paper 3 by driving the actuator means of the recording head 14 in accordance with the image to be recorded while moving the carriage 13 in the main scanning direction (step S5).

[0051] After printing by the recording head 14 is completed, the first branch claw 46 has been switched to the double-sided printing side, so the recording paper 3 is guided by the guide member 45 and fed between the switchback roller 47 and the switchback driven roller 48, and is then transported by these switchback roller 47 and switchback driven roller 48 and discharged outside the device main body 1. At this time, the control unit 50a of the inkjet printer 50 determines that printing on the front side is completed (Yes in step S6), and stops the switchback roller 47 when the rear end of the recording paper 3 is positioned between the switchback roller 47 and the switchback driven roller 48 (step S7), thereby clamping the rear end of the recording paper 3.

[0052] Next, the control unit 50a of the inkjet printer 50 switches the first branch claw 46 to the paper discharge side (step S8), switches the second branch claw 49 to the paper re-feed side (step S9), and then reverses the switchback roller 47 (step S10) and drives the double-sided relay roller 52, thereby refeding the recording paper 3, whose edge was held between the switchback roller 47 and the switchback driven roller 48, onto the conveyor belt 23 while guiding the recording paper 3 with the guide member 51. In this case, the control unit 50a of the inkjet printer 50 sets the paper feed linear speed when refeding the recording paper 3 to be approximately the same as the linear speed of the conveyor belt 23.

[0053] The control unit 50a of the inkjet printer 50 prints an image on the reverse side (other side) of the recording paper 3 fed again in this way by the recording head 14 while conveying the recording paper 3 by the conveyor belt 23 (step S11).

[0054] When the control unit 50a of the inkjet printer 50 determines that printing on the back side has been completed (Yes in step S12), it guides the recording paper 3 on which printing by the recording head 14 has been completed via the first branch claw 46 to the guide member 41 on the paper discharge side, and transports it between the paper discharge roller 42 and the paper discharge driven roller 43 to discharge it into the paper discharge tray 6 (step S13).

[0055] Next, a process for printing specific image information in the inkjet printer 50 will be described.

[0056] In the inkjet printer 50 of this embodiment, the selection of whether or not to print specific image information (IR image information) with IR ink on the other side (rear side) of the recording paper 3 (this is called "IR printing (invisible printing)") can be made by selection and specification from the operation panel 8 and selection and specification from the printer driver 101 of the host 100. Furthermore, in the inkjet printer 50 of this embodiment, it is also possible to select whether to print IR on the front side or the back side.

[0057] Furthermore, the inkjet printer 50 of this embodiment can use the following methods (1) to (3) as a method for inputting specific image information (IR image information) for IR printing. (1) A method in which specific image information (IR image information) of a plurality of patterns is stored in advance in the control unit 50a of the inkjet printer 50, and the image information is selected and designated from the printer driver 101 or the operation panel 8. (2) A method in which specific image information (IR image information) of multiple patterns is stored in advance in the printer driver 101 of the host 100, and the selected pattern is selected and designated in the print properties of the printer driver 101, and the selected and designated pattern is transferred to the inkjet printer 50 together with the input image information to be printed. (3) A method of inputting specific image information (IR image information) from an external imaging device (external device), such as the scanner 90 described above (explained in FIG. 4), a storage medium such as a FD / USB, a digital camera, a digital video, or other imaging device.

[0058] In addition, in an application that can specify a spot color (IR) included in the inkjet printer 50 of this embodiment, an invisible image specified with the spot color (IR) is printed on the side for which IR printing is specified. In addition, in a normal application that the inkjet printer 50 of this embodiment has, it is also possible to print a visible image on odd-numbered pages and an invisible image on even-numbered pages. Note that the odd-numbered and even-numbered pages may be reversed.

[0059] Of these input methods, method (1) is particularly effective for standardized data. For example, if you want to input the same data, such as standardized data like a "security mark" or "QR code (registered trademark)," you can store it in the ROM 71, for example, of the control unit 50a of the inkjet printer 50 as standard equipment, eliminating the need to create and input specific image information (IR image information) as an invisible image. Furthermore, because the data does not go through another application, it is possible to have data optimized from the start for print speed, image quality, font, size, layout, etc., thereby always maintaining consistent quality and enabling standardization of formats.

[0060] When using input method (1), the selection is generally made on the printer driver 101, but it can also be made on the operation panel (control panel) 8 of the inkjet printer 50. In particular, when the inkjet printer 50 is used as a multifunction machine that combines a copier, facsimile, and printer, or as a printer connected to a network, fixing the pattern of specific image information (IR image information) as an "invisible image" on the operation panel (control panel) 8 makes it possible to standardize the specific image information (IR image information) as an "invisible image" under that network.

[0061] Next, method (2) is a common method, and when using an application that supports spot colors (PhotoShop (registered trademark), Illustrator (registered trademark), etc.), an image with a specified spot color (IR) can be printed on the side where the visible image is printed, and the visible image portion can be printed on the opposite side. Also, with normal applications (Word (registered trademark), Excel (registered trademark), PowerPoint (registered trademark), etc.), it is possible to print the visible image on odd-numbered pages and the invisible image on even-numbered pages. As mentioned above, the odd-numbered and even-numbered pages can also be reversed.

[0062] Furthermore, with method (3), data can be captured using external input devices, the variety of which has been increasing in recent years, making it possible to use QR codes, serial numbers, drawings, photographs, etc. While flatbed scanners are commonly used to input analog data such as photographs and drawings, some printers now come with built-in scanners and scanner units that can be installed in place of the print head unit (liquid ejection unit). Furthermore, input devices such as digital cameras and digital video cameras make it possible to capture data from three-dimensional or moving objects. In this case, by providing an interface for receiving data from an external device, such as the one shown in Figure 4, it becomes possible to input data directly from external imaging devices, allowing various image information to be used as invisible images.

[0063] In this case, the input method for the specific image information (IR image information) to be output can be any one of the above (1) to (3), but in this embodiment, they can be used in combination.

[0064] First, a method (1) will be described in which data for a plurality of patterns is stored in advance in the control unit 50a of the inkjet printer 50, and selection is specified from the printer driver 101 or the operation panel 8.

[0065] Here, Fig. 6 is a flowchart showing the flow of the IR printing designation process. As shown in Fig. 6, when an input is received from the operation panel 8 (Yes in step S21), the control unit 50a of the inkjet printer 50 determines what type of IR printing has been designated, and executes an IR image input selection process to select the input of specific image information (IR image information) using the designated method (step S22).

[0066] Here, when selection of a fixed pattern of specific image information (IR image information) is selected ("Fixed" in step S23), the control unit 50a of the inkjet printer 50 performs a fixed pattern selection process of displaying the fixed pattern of the specific image information (IR image information) stored in the ROM 71 on the display unit of the operation panel 8 and storing the selected fixed pattern as specific image information (IR image information) in a predetermined area of ​​the RAM 72 (step S24). On the other hand, when an external device is selected ("External" in step S23), the control unit 50a of the inkjet printer 50 performs a process of importing an image input from the external device and storing it as specific image information (IR image information) in a predetermined area of ​​the RAM 72 (step S25).

[0067] The control unit 50a of the inkjet printer 50 then determines whether or not to edit the specific image information (IR image information) (step S26). When editing is instructed (Yes in step S26), the control unit 50a of the inkjet printer 50 performs editing processing (step S27). In the editing processing, the control unit 50a of the inkjet printer 50 can perform editing such as enlarging, reducing, positioning, and repeating the image. For example, if the original data of the specific image information (IR image information) is too large compared to the image to be printed on the front side (one side), the control unit 50a of the inkjet printer 50 can perform processing to reduce the original data to an optimal size, or enlarge the original data if the original data is too large compared to the image to be printed on the front side (one side). The control unit 50a of the inkjet printer 50 can also perform editing such as arranging the specific image information (IR image information) in a desired position on the paper, such as the center, lower right, lower left, upper right, or upper left, or repeatedly arranging the same specific image information (IR image information).

[0068] By having a means for editing specific image information (IR image information) in this way, it is possible to rotate the input data, change the output position, or output repeatedly to create a more desired layout for the output on the back side (specific image information (IR image information)). Also, by making it possible to enlarge or reduce the size, it is possible to avoid situations where, for example, back side data is prepared that is much larger than the front side data, thereby reducing the burden in terms of capacity and printing speed.

[0069] Invisible printing, which prints specific image information (IR image information), can sometimes print barcodes or QR codes for security purposes. Since invisible printing cannot be copied by a copy machine, it can be used for security printing.

[0070] To improve the readability of barcodes and QR codes, the print density of specific image information (IR image information) can be adjusted to improve the reading accuracy of infrared cameras, infrared readers, etc.

[0071] 7 is a diagram showing an example of an IR print setting screen. For example, the control unit 50a of the inkjet printer 50 can adjust the print density by changing at least one of the brightness A1 and the contrast A2 in the color balance editing on the IR print setting screen shown in FIG. 7 displayed on the operation panel 8 during the editing process (step S27) of the IR print specification process. Note that the change of at least one of the brightness A1 and the contrast A2 may be performed by the printer driver 101.

[0072] When printing barcodes or QR codes with IR ink, the darker the IR ink, the more accurate the reading, so as described above, it is possible to individually adjust the print density of specific image information (IR image information).

[0073] If no editing instruction is given (No in step S26), the control unit 50a of the inkjet printer 50 proceeds to step S29.

[0074] Next, when the control unit 50a of the inkjet printer 50 determines that editing is complete (Yes in step S28), it performs processing to create a mirror image of the captured IR image that is flipped left to right (same top and bottom) (step S29). That is, the inkjet printer 50 selects the first output mode in which the output result of specific image information (IR image information) becomes a mirror image that is flipped left to right (a normal image when viewed from the opposite side of the paper).

[0075] In this way, by printing specific image information (IR image information) on the back side as a mirror image with the left and right reversed (but the top and bottom are the same as on the front side), the amount of ink adhered to one side can be reduced.

[0076] Next, we will explain method (2) in which specific image information (IR image information) of multiple patterns is stored in advance in the printer driver 101 of the host 100, selected and specified in the printing properties of the printer driver 101, and the specific image information (IR image information) of the selected and specified pattern is transferred to the inkjet printer 50 together with the image information to be printed.

[0077] FIG. 8 is a flowchart showing the flow of the IR print designation process performed by the printer driver 101 of the host 100. In FIG.

[0078] 8, the printer driver 101 of the host 100 displays an IR print setting screen for specifying the type of invisible printing (IR printing) to be performed (step S31). The IR print setting screen accepts settings such as, for example, selection of a fixed pattern as specific image information (IR image information), selection of an external device for inputting the specific image information (IR image information), printing the specific image information (IR image information) on even-numbered pages, and use of an application that can specify a spot color (IR).

[0079] Next, the printer driver 101 of the host 100 sets the various IR printing related items received via the IR print setting screen (step S32), and then displays the IR image setting screen (step S33).

[0080] Here, Fig. 9 is a diagram showing an example of the IR print setting screen. As shown in Fig. 9, the IR print setting screen displays a check box CK1 that allows the user to select invisible printing (IR printing), which prints specific image information using spot color ink (IR ink) on the other side (rear side) of the recording paper 3. When the check box CK1 is checked, the printer driver 101 of the host 100 determines that invisible printing (IR printing) has been selected.

[0081] The IR print setting screen also displays a check box CK2 that allows the user to select the side on which invisible printing (IR printing) will be performed. If the check box CK2 is checked, the printer driver 101 of the host 100 determines that selection of the side on which invisible printing (IR printing) will be performed has been selected. If the check box CK2 is checked, the IR print setting screen also displays check boxes CK3 and CK4 that allow the user to select whether the side on which invisible printing (IR printing) will be performed will be odd-numbered pages (front side) or even-numbered pages (back side). If the check box CK3 is checked, the printer driver 101 of the host 100 determines that selection of the side on which invisible printing (IR printing) will be performed will be odd-numbered pages (front side). If the check box CK4 is checked, the printer driver 101 of the host 100 determines that selection of the side on which invisible printing (IR printing) will be performed will be even-numbered pages (back side).

[0082] The IR print setting screen also displays a check box CK5 that allows the user to select an IR stamp (specific image information (IR image information)) as a fixed pattern as an image for invisible printing (IR printing). When the check box CK5 is checked, the printer driver 101 of the host 100 determines that the IR stamp (specific image information (IR image information)) has been selected.

[0083] Furthermore, when the check box CK5 is checked and the edit button B1 is pressed, the IR print setting screen allows editing of the IR stamp (specific image information (IR image information)).

[0084] 10 is a diagram showing an example of an editing screen for an IR stamp (specific image information (IR image information)). As shown in Fig. 10, the editing screen for an IR stamp (specific image information (IR image information)) accepts the designation of specific image information (IR image information) as an image stamp C1, as well as settings such as a print position C2, a stamp name C3, a path name / file name C4, and a size C5.

[0085] When the printer driver 101 of the host 100 is instructed to use specific image information (IR image information) (called a "built-in pattern") that is built into the printer driver 101 and / or the host 100 (including data imported from the outside) (Yes in step S34), it performs a process of selecting a pattern to use from among multiple built-in patterns (step S35).

[0086] Thereafter, the printer driver 101 of the host 100 performs an editing process (step S36), and then performs a mirroring process (step S37).

[0087] When external input is instructed (No in step S34, Yes in step S38), the printer driver 101 of the host 100 performs an external input designation process that instructs the inkjet printer 50 to import specific image information (IR image information) from an external device (step S39), and then performs a mirroring process (step S37).

[0088] When the printer driver 101 of the host 100 is instructed to use specific image information (IR image information) of a fixed pattern of the inkjet printer 50 (No in step S34, No in step S38, Yes in step S40), it performs a fixed pattern selection process to specify the specific image information (IR image information) of the fixed pattern of the inkjet printer 50, for example, by number (step S41), and then performs a mirroring process (step S37).

[0089] If there is no instruction (No in step S34, No in step S38, No in step S40), the printer driver 101 of the host 100 proceeds directly to step S42.

[0090] After executing the mirroring process (step S37), the printer driver 101 of the host 100 determines whether the process has ended (step S42). The printer driver 101 of the host 100 repeats the processes of steps S31 to S41 until it determines that the process has ended (OK) (Yes in step S42).

[0091] In this way, by having specific image information (IR image information) patterns on the printer driver 101 side of the host 100 and allowing the user to select and specify them, it becomes easy to input specific image information (IR image information) even when the host 100 side and the inkjet printer 50 are far apart in distance.

[0092] When transferring image information to be printed (which becomes input image information), this printer driver 101 transfers to the inkjet printer 50 data specifying invisible printing (IR printing), specific image information to be used (IR image information), or data related to the import of specific image information to be used (IR image information) (in the case of an external device or a fixed pattern of the inkjet printer 50). Although not shown, the printer driver 101 also performs a selection and designation process for determining whether or not to change image processing, ink droplet ejection characteristics, recording density, etc., and transfers the selection results to the inkjet printer 50. The printer driver 101 can be stored in a storage medium readable by the host 100 computer, or can be installed and used via a network such as the Internet.

[0093] Next, an example of the IR printing process on the inkjet printer 50 side will be described.

[0094] Here, Fig. 11 is a flowchart showing the flow of the IR printing process. As shown in Fig. 11, the control unit 50a of the inkjet printer 50 performs a process of determining whether or not invisible printing (IR printing) has been selected on the IR printing setting screen shown in Fig. 9 (step S51). Here, the control unit 50a of the inkjet printer 50 determines whether or not information selecting invisible printing (IR printing) provided by the printer driver 101 of the host 100 (this information is referred to as "IR printing designation information") has been input, and if the IR printing designation information has not been input from the printer driver 101 of the host 100, the control unit 50a determines whether or not the IR printing designation information has been input from the operation panel 8. In other words, the designation on the host 100 side takes priority, but it is also possible to give priority to the designation from the operation panel 8.

[0095] If invisible printing (IR printing) is not selected (No in step S52), the control unit 50a of the inkjet printer 50 executes normal printing processing.

[0096] When invisible printing (IR printing) is selected (Yes in step S52), the control unit 50a of the inkjet printer 50 performs a process of importing specific image information (IR image information) (step S53). That is, when invisible printing (IR printing) is specified by the printer driver 101 of the host 100, the control unit 50a determines whether specific image information (IR image information) has been input from the host 100. If specific image information (IR image information) has been input from the host 100, the control unit 50a imports the input image as specific image information (IR image information). When no image has been input, if import from an external device has been specified, the control unit 50a imports specific image information (IR image information) from the external device as described above. If a fixed pattern has been specified, the control unit 50a imports specific image information (IR image information) of the specified fixed pattern. When invisible printing (IR printing) is specified from the operation panel 8, the control unit 50a imports the selected pattern (specific image information (IR image information) of the fixed pattern or specific image information (IR image information) input from an external device) as described above.

[0097] Thereafter, the control unit 50a of the inkjet printer 50 proceeds to a process for setting parameters for invisible printing (IR printing) (step S54). The control unit 50a of the inkjet printer 50, for example, determines whether or not to change image processing, and if it is a change in image processing, performs a process for changing the color balance, gamma correction value, UCR, etc., then determines whether or not to change ink droplet ejection characteristics (here, the ink droplet ejection speed Vj and the ink droplet ejection volume Mj are the targets), and if it is a change in ejection characteristics, changes the ink droplet ejection speed Vj and the ink droplet ejection volume Mj, then determines whether or not to change recording density, and if it is a change in recording density, performs a process for lowering or increasing the recording density, etc.

[0098] That is, in invisible printing (IR printing), specific image information (IR image information) on the back side is viewed from the front side through an infrared camera, infrared reader, etc., so the specific image information (IR image information) on the back side may appear to overlap with the image on the front side, and in such cases the colors of the front and back sides may affect each other, changing the color tone or making the image on the front side difficult to see. Therefore, by automatically or manually switching the image processing methods for the front and back sides and performing color conversion, gamma correction, UCR, etc. that take into account the specific image information (IR image information) on the back side, it is possible to minimize changes in color tone and density and prevent a decrease in image quality on the front side.

[0099] Also, depending on the combination of recording paper 3 and ink, the transparency may be extremely low or high, so by performing gamma correction that takes the transmission density into account in the image processing of the back side, it is possible to adjust the density to the optimum level.

[0100] Furthermore, depending on the recording paper 3, the ink penetration speed may differ significantly between the front and back sides, and in some cases, the ink may penetrate too much and bleed onto the front side, reducing image quality. Therefore, by manually or automatically switching the ink droplet volume Mj, etc., it is possible to print optimal specific image information (IR image information). Also, since the specific image information (IR image information) output on the back side does not require the same resolution as the image on the front side, printing throughput can be improved by outputting it at a lower resolution than the front side.

[0101] The parameters for invisible printing (IR printing) may be set on an IR printing setting screen for invisible printing (IR printing) in the printer driver 101 of the host 100.

[0102] Thereafter, the control unit 50a of the inkjet printer 50 prints the input image information (input image information) on the front surface (one side) of the recording paper 3 (step S55).

[0103] After printing the input image information (input image information) on the front surface (one side) of the recording paper 3, the control unit 50a of the inkjet printer 50 stops the printing operation for a time period for the ink to dry (step S56).

[0104] Next, the control unit 50a of the inkjet printer 50 performs the double-sided printing operation as described above, re-feeds the printed recording paper 3, prints the selected specific image information (IR image information) in mirror image on the back (other side) of the recording paper 3, and ejects the paper (step S57).

[0105] As mentioned above, when printing on the back side (other side) after printing on the front side (one side), the printing operation is stopped long enough for the ink to dry, which allows a certain amount of time between printing on the front side (one side) and printing on the back side (other side), ensuring time for the ink to dry during printing. By drying the ink in this way, it is possible to increase the amount of ink that adheres to one side compared to when the ink is not allowed to dry.

[0106] The above-mentioned operation of pausing printing for the time it takes for the ink to dry is also performed by some general inkjet printers when printing on both sides. In other words, this method can be implemented without making major changes to current inkjet printers.

[0107] In addition, in the operation of stopping the printing operation for the time it takes for the ink to dry as described above, if the amount of ink attached to the surface (one side) of the recording paper 3 is small, the drying time will be short, so the stop time may be controlled to be short.

[0108] Note that when printing on the reverse side (other side) of the recording paper 3, there is no time pause to allow the ink to dry because the ink dries during the time while the printing process for the next recording paper 3 is being executed, so there is no need to pause the printing operation for the time it takes for the ink to dry.

[0109] From the above, it can be seen that printing an image with a small amount of ink per unit area on the front (one side) of the recording paper 3 results in a faster printing speed than printing an image with a large amount of ink per unit area on the front (one side) of the recording paper 3.

[0110] Basically, IR image information requires a smaller maximum amount of ink, so printing from IR image information results in a faster printing speed. However, in some cases, the visible image may require a smaller amount of ink per unit area, so the user manually selects from the operation panel 8 or the like whether to print the IR image information on the front side (one side) or the back side (other side).

[0111] The control unit 50a of the inkjet printer 50 is 2 ) and automatically determine whether the visible side or the IR side should be facing up.

[0112] The ink drying time can be manually set, for example, by the printer driver 101 of the host 100. Here, Fig. 12 is a diagram showing an example of an IR print setting screen for invisible printing (IR printing) in the printer driver 101 of the host 100. On the IR print setting screen shown in Fig. 12, it is possible to set the drying wait time D1 for the front side (one side).

[0113] The above-mentioned invisible printing (IR printing) will now be described in detail.

[0114] Here, Fig. 13 is a diagram for explaining a specific example of invisible printing (IR printing). For example, a case will be explained in which image information (input image information) to be printed on the front side (one side) as shown in Fig. 13(a) is input, and specific image information (IR image information) (illustrated as normal image data) to be printed on the back side (other side) as shown in Fig. 13(b) is selected.

[0115] The image information (input image information) shown in Figure 13(a) is a visible image drawn by an application, and is an example of an image printed on the front (one side) of recording paper 3 using three colors of CMY ink: yellow, magenta, and cyan.

[0116] The control unit 50a of the inkjet printer 50 prints the image information (input image information) of Figure 13(a) on the front (one side) of the recording paper 3, and prints the specific image information (IR image information) shown in Figure 13(c) which is a mirror image of the specific image information (IR image information) of Figure 13(b) on the back (other side) of the recording paper 3.

[0117] The specific image information (IR image information) shown in Figure 13(c) is a mirror image of the specific image information (IR image information) in Figure 13(b), and is an example printed in IR ink on the back (other side) of the recording paper 3. In other words, the specific image information (IR image information) shown in Figure 13(c) printed on the back (other side) of the recording paper 3 is printed so that it is in the correct position and in the correct direction when viewed from the front (one side) of the recording paper 3. Note that although the specific image information (IR image information) is displayed in Figure 13(c), it is actually invisible.

[0118] The specific image information (IR image information) shown in Fig. 13(c) is an example printed with IR ink when a fixed pattern, an even page of the application (or an odd page in some cases: specified on the panel), and an application that can set a spot color are set. When a fixed pattern, an even page of the application (or an odd page in some cases: specified on the panel), and an application that can set a spot color are set, the image is drawn as seen from the front (one side) of the recording paper 3 with an infrared camera, infrared reader, etc. as shown in Fig. 13(b), but is printed as shown in Fig. 13(c) by the mirroring process (step S29) described in Fig. 6.

[0119] 13(d), the specific image information (IR image information) printed on the back (other side) of the recording paper 3 using the double-sided printing function of the inkjet printer 50 is printed in the correct position and in the correct orientation when viewed from the front (one side) of the recording paper 3. Therefore, the specific image information (IR image information) printed on the back (other side) of the recording paper 3 is printed as a normal image. The invisible print printed on the back (other side) of the recording paper 3 has a certain degree of transparency, so it can be seen in the correct orientation when viewed from the front (one side) of the recording paper 3 with an infrared camera, infrared reader, etc.

[0120] In this way, the added value of the print result can be increased by outputting input image information on the front (one side) of the recording paper 3 and outputting specific image information (IR image information) that is set separately from the input image information (or in some cases set by an app) on the back (other side) of the recording paper 3.

[0121] Here, Figure 14 is a diagram showing an example of image formation by liquid ejection recording. In liquid ejection recording, ink droplets D that land on recording paper 3 as shown in Figure 14(a) penetrate and dry, forming an image G on recording paper 3 as shown in Figure 14(b). Therefore, unless the recording paper is specially treated to trap coloring material on the paper surface, such as inkjet paper, show-through and strike-through are likely to occur.

[0122] Conventionally, when performing visible printing of input image information using CMY inks on one side and invisible printing of specific image information (IR image information) using IR inks, the amount of ink attached to one side increases by the amount of IR ink, causing the recording paper 3 to ripple or bleed together, resulting in a decrease in image quality. Also, when performing visible printing of input image information using CMY inks on one side and invisible printing of specific image information (IR image information) using IR inks on the other side, it is possible to reduce the amount of ink attached, but reducing the amount of ink attached causes a problem of the printed image becoming faint.

[0123] For example, in the image shown in FIG. 13(a), CMY inks are printed by overlapping them, so the ink can be applied up to 300% (100% is a solid color). However, applying 300% CMY inks exceeds the amount of ink that the recording paper 3 can absorb, causing many problems, such as rippling and show-through. Therefore, the ink amount is often limited. Furthermore, if the amount of ink applied is large, there is also the problem that it takes a long time for the ink to dry. For example, in this embodiment, the maximum ink amount is set to 250% or less. On the other hand, the back side (other side) of the recording paper 3 shown in FIG. 13(c) uses only IR ink, so the maximum ink amount is 100%. Therefore, the maximum ink amount is 250% on the front side (one side) of the recording paper 3 and 100% on the back side (other side) of the recording paper 3, and the ink amount tends to be less on the back side (other side) of the recording paper 3.

[0124] In contrast, according to this embodiment, when recording is performed by ejecting liquid using an inkjet printer 50, specific image information (IR image information) is printed on the back side (other side) of the recording paper 3. After printing on the front side (one side) of the recording paper 3, the ink on the front side (one side) of the recording paper 3 dries, and then the back side (other side) of the recording paper 3 is printed. This solves the problem of image quality being reduced because the amount of ink adhering to one side increases and exceeds the amount of ink that the recording paper 3 can absorb, causing the recording paper 3 to ripple or the ink to bleed. Furthermore, according to this embodiment, the invisible printing is printed on the opposite side of the visible image, which solves problems such as gloss differences due to invisible printing and the invisible printing being visible, thereby achieving high image quality.

[0125] Furthermore, according to this embodiment, printing on the side with less ink first dries faster, which also results in faster printing. The visible side on which the visible image is printed can carry up to 250% ink, while the invisible side on which the specific image information (IR image information) is printed is 100%. Therefore, basically, printing on the side on which the specific image information (IR image information) is printed first dries faster, which also results in faster printing.

[0126] Next, IR image editing will be described.

[0127] Here, Figures 15 to 17 are diagrams showing specific examples of editing processing in invisible printing (IR printing). As mentioned above, it is possible to further modify (edit) the input specific image information (IR image information). For example, as shown in Figure 15(a), if the original data of the specific image information (IR image information) is too large compared to the input image information for the front (one side) of the recording paper 3, it can be reduced to an optimal size and printed at an appropriate size as shown in Figure 15(b). Conversely, the image size can also be enlarged. Since the enlargement processing requires only a small image, i.e., a small amount of data, it is possible to prevent the system from being burdened by preparing data that is larger than necessary.

[0128] Also, as shown in Fig. 16, by making it possible to freely adjust the layout of specific image information (IR image information), it is possible to position it in a way that makes it easy to find the reading location with an infrared camera, infrared reader, etc. by overlapping it with the input image information on the front (one side) of the recording paper 3. Furthermore, as shown in Fig. 17, by repeatedly arranging specific image information (IR image information) such as a QR code, it is possible to intentionally improve reading by an infrared camera, infrared reader, etc.

[0129] As described above, the inkjet printer 50 according to this embodiment is capable of double-sided printing, and is configured to output input image information to the front (one side) of the recording paper 3, and output specific image information (IR image information) that is set separately from the input image information (or, in some cases, as input information) to the back (other side) of the recording paper 3. Therefore, by printing on the back (other side) of the recording paper 3, printing can be done without reducing the amount of ink, and visibility from the front (one side) of the recording paper 3 using an infrared camera, infrared reader, etc. can be improved, thereby increasing the added value of the printed matter.

[0130] Furthermore, according to the inkjet printer 50 of this embodiment, the output result of the IR image information is a mirror image that is inverted left and right, so that specific image information (IR image information) can be printed as a normal image from the front (one side) of the recording paper 3, and the specific image information (IR image information) can be easily grasped using an infrared camera, infrared reader, etc.

[0131] The inkjet printer 50 according to this embodiment is provided with a means for selecting either the first output mode or the second output mode, allowing the user to select whether to print a visible image on the front (one side) of the recording paper 3 and an invisible image on the back (other side) of the recording paper 3, or to print an invisible image on the front (one side) of the recording paper 3 and a visible image on the back (other side) of the recording paper 3. If the back (other side) on which specific image information (IR image information) is printed is printed first, the ink dries quickly, allowing printing of the visible image on the front (one side) to begin sooner. Generally, printing specific image information (IR image information) first is faster, but the reverse may be better depending on the print pattern, so this option should be selectable.

[0132] Furthermore, by having a means for pre-storing specific image information (IR image information), the time and effort required for creating and inputting standardized images is eliminated, print throughput is improved, image quality is improved, and standardized images used over a network can be achieved. Furthermore, by inputting specific image information (IR image information) from the host 100 side, the time and effort required for creating and inputting standardized images is eliminated, print throughput is improved, and image quality is improved. Furthermore, by providing an interface for connecting imaging devices, a wide variety of images can be used as specific image information (IR image information).

[0133] Furthermore, by providing a means for editing specific image information (IR image information), it is possible to give specific image information a layout, size, etc. that is more likely to attract the user's attention, and it is also possible to reduce the burden on memory capacity and printing speed.

[0134] Furthermore, by making it possible to adjust the density (ink amount) of specific image information (IR image information), it is possible to improve the reading accuracy of QR codes and the like printed with IR ink.

[0135] As described above, according to this embodiment, it is possible to form a visible image using visible ink and an invisible image using invisible ink without reducing the amount of ink attached.

[0136] Furthermore, the recording density when specific image information (IR image information) is output to the back side (other side) of the recording paper 3 can be made different from the image density when input image information is output to the front side (one side) of the recording paper 3. In this case, it is possible to select whether or not to make the recording density when specific image information (IR image information) is output to the back side (other side) of the recording paper 3 different from the recording density when input image information is output to the front side (one side) of the recording paper 3.

[0137] The storage medium of the present invention is a computer-readable storage medium that stores a printer driver for driving and controlling an inkjet printer 50 capable of double-sided printing, and stores the printer driver having a means for setting specific image information on the back side (other side) of the recording paper 3 that is different from the input image information to be recorded on the front side (one side) of the recording paper 3.

[0138] The data processing device of the present invention is a data processing device capable of transferring data to an inkjet printer 50, and is equipped with a means for setting specific image information (IR image information) on the back side (other side) of the recording paper 3, which is different from the input image information to be recorded on the front side (one side) of the recording paper 3.

[0139] Inkjet printers 50 include not only desktop types, but also wide-width image forming devices that can print on A0-sized recording media, and continuous feed printers that can use continuous paper wound into a roll as a recording medium.

[0140] In the above embodiments, the image forming apparatus of the present invention has been described as being applied to an inkjet printer, but the present invention can be applied to any image forming apparatus such as a multifunction machine, copier, or facsimile machine that has at least two of the following functions: copy function, printer function, scanner function, and facsimile function.

[0141] Although the embodiments of the present invention have been described above, each embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Each of these embodiments is included within the scope and spirit of the invention, and is also included in the inventions described in the claims and their equivalents.

[0142] For example, aspects of the present invention are as follows. <1> An image forming apparatus comprising: an image forming unit including a liquid ejection head having a plurality of nozzles for ejecting liquid onto a medium; and a control unit, the control unit controls the image forming unit so that the liquid ejection head ejects a liquid that absorbs visible light but does not absorb invisible light onto one side of the medium to form a visible image, and the liquid ejection head ejects a liquid that absorbs invisible light onto the other side of the medium to form an invisible image. The image forming apparatus is characterized by the above. <2> the liquid that absorbs invisible light contains an infrared absorbing material that absorbs light in the near-infrared region, The invisible image is an image that becomes visible when irradiated with infrared rays. Characterized by <1> 2. The image forming apparatus according to claim 1 . <3> the control unit controls the image forming unit to form an invisible image on the other surface of the medium as a mirror image of the invisible image that has been flipped left and right. Characterized by <2> 2. The image forming apparatus according to claim 1 . <4> the control unit determines whether or not to display the invisible image as a mirror image, in accordance with a setting in a printer driver; Characterized by <3> 2. The image forming apparatus according to claim 1 . <5> the control unit controls the image forming unit to temporarily stop a formation operation after completing formation of the visible image on one side of the medium, and then to form the invisible image on the other side of the medium. Characterized by <1> Or <4> 10. The image forming apparatus according to claim 9, wherein <6> when forming the visible image using a liquid that absorbs the three colors of visible light but does not absorb invisible light, the control unit controls the image forming unit so that the amount of the liquid that absorbs the visible light but does not absorb invisible light attached to one side of the medium is 250% or less per unit area. Characterized by <1> Or <5> 10. The image forming apparatus according to claim 9, wherein <7> the control unit is capable of setting whether one side or the other side of the medium is to be formed first. Characterized by <1> Or <6> 10. The image forming apparatus according to claim 9, wherein <8> the control unit controls the image forming unit to form the visible image on one side of the medium after forming the invisible image on the other side of the medium. Characterized by <1> Or <7> 10. The image forming apparatus according to claim 9, wherein <9> An image forming method in an image forming apparatus including an image forming unit including a liquid ejection head having a plurality of nozzles that eject liquid onto a medium, and a control unit, comprising: the control unit controls the image forming unit so that the liquid ejection head ejects a liquid that absorbs visible light but does not absorb invisible light onto one side of the medium to form a visible image, and the liquid ejection head ejects a liquid that absorbs invisible light onto the other side of the medium to form an invisible image, An image forming method comprising: [Explanation of symbols]

[0143] 2 Image forming unit 3 Medium 14 Liquid ejection head 50 Image forming device 50a Control unit [Prior art documents] [Patent documents]

[0144] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-079708

Claims

1. An image forming apparatus comprising: an image forming unit including a liquid ejection head having a plurality of nozzles for ejecting liquid onto a medium; and a control unit, the control unit controls the image forming unit so that the liquid ejection head ejects a liquid that absorbs visible light but does not absorb invisible light onto one side of the medium to form a visible image, and the liquid ejection head ejects a liquid that absorbs invisible light onto the other side of the medium to form an invisible image. The image forming apparatus is characterized by the above.

2. the liquid that absorbs invisible light contains an infrared absorbing material that absorbs light in the near-infrared region, The invisible image is an image that becomes visible when irradiated with infrared rays.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. the control unit controls the image forming unit to form an invisible image on the other surface of the medium as a mirror image of the invisible image that has been flipped left and right.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the control unit determines whether or not to display the invisible image as a mirror image, in accordance with a setting in a printer driver; 4. The image forming apparatus according to claim 3, wherein the image forming apparatus is a recording medium.

5. the control unit controls the image forming unit to temporarily stop a formation operation after completing formation of the visible image on one side of the medium, and then to form the invisible image on the other side of the medium.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. when forming the visible image using a liquid that absorbs the three colors of visible light but does not absorb invisible light, the control unit controls the image forming unit so that the amount of the liquid that absorbs the visible light but does not absorb invisible light applied to one side of the medium is 250% or less per unit area.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. the control unit is capable of setting whether one side or the other side of the medium is to be formed first.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. the control unit controls the image forming unit to form the visible image on one side of the medium after forming the invisible image on the other side of the medium.

8. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. An image forming method in an image forming apparatus including an image forming unit including a liquid ejection head having a plurality of nozzles that eject liquid onto a medium, and a control unit, comprising: the control unit controls the image forming unit so that the liquid ejection head ejects a liquid that absorbs visible light but does not absorb invisible light onto one side of the medium to form a visible image, and the liquid ejection head ejects a liquid that absorbs invisible light onto the other side of the medium to form an invisible image, An image forming method comprising:

Images