Printing device

Abstract

To provide a printing device, which can solve the problem that it is difficult for the device to detect a minute disorder which makes application thereof to water-based ink difficult.SOLUTION: A printing device 10 comprises: a conveying part 20 that conveys a printing medium B along a conveyance path; a supporting part 40 that supports the printing medium B being conveyed by the conveying part 20; a printing part 30 that forms an image on the printing medium B supported by the supporting part 40 by discharging liquid to the medium; a fixing part 50 that fixes the discharged liquid, in the middle of the conveyance path; and an inspecting part 60 that inspects a fixation state of liquid fixed to the printing medium B passing through the fixing part 50. The conveying part 20 has a printing surface contact roller 23, arranged at a downstream side of the fixing part 50 on the conveyance path, which contacts a surface of the printing medium B. The inspecting part 60 has a line sensor 61 that inspects a state of a peripheral surface of the printing surface contact roller 23, and a determining part 71 that determines the fixation state of liquid fixed to one surface of the printing medium B, on the basis of output from the line sensor 61.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a printing device, and more particularly to a printing device in which ejected liquid is fixed by a fixing unit. [Background technology]

[0002] Some printing devices that eject liquid to print are equipped with a fixing unit such as a drying oven to fix the liquid onto the medium, and some are also equipped with an inspection unit to confirm that the liquid has been properly fixed. The technology disclosed in Patent Document 1 involves bringing a brush into contact with the surface of a print that has been cured by irradiating it with ultraviolet light, and capturing an image of the print using an imaging device located downstream of the brush. The print result obtained from the image is compared with the print data to determine the state of ink curing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-123663 Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional method described above requires the detection of minute image disturbances caused by brush contact before the UV ink solidifies, which requires the use of expensive, high-performance imaging devices, and requires advanced image matching technology to detect minute disturbances. Furthermore, the print data to be matched must be changed each time the inspection target changes.

[0005] Furthermore, it can only be applied to things like UV inks, which form an ink film on the surface of the printed material, and it is difficult to apply it to water-based inks that are absorbed by paper-based printing media. [Means for solving the problem]

[0006] The printing device of the present invention comprises a transport unit that transports a printing medium along a predetermined transport path, a support unit that supports the printing medium, a printing unit that ejects liquid onto one side of the printing medium supported by the support unit to form an image, a fixing unit that fixes the liquid ejected by the printing unit and adhered to the one side along the transport path, and an inspection unit that inspects the fixation state of the liquid adhered to the one side of the printing medium that has passed through the fixing unit, wherein the transport unit has a printing surface contact roller that is positioned downstream of the fixing unit on the transport path and contacts the one side, and the inspection unit has a sensor that inspects the state of the circumferential surface of the printing surface contact roller, and a judgment unit that judges the fixation state of the liquid adhered to the one side of the printing medium based on the output of the sensor. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of a printing apparatus to which the present invention is applied; [Figure 2] FIG. 2 is a schematic block diagram of the printing apparatus. [Figure 3] FIG. 2 is a schematic diagram of the printing surface contact roller of the transport section and the inspection section. [Figure 4] FIG. 10 is a diagram showing the print surface contact roller and the sensor output. [Figure 5] FIG. 10 is a diagram showing the print surface contact roller and the sensor output. [Figure 6] 4 is a flowchart corresponding to a control program. [Figure 7] FIG. 10 is a diagram showing a modified example of the inspection unit. [Figure 8] 10A and 10B are diagrams illustrating the output of a sensor of an inspection unit and a printing surface contact roller according to a modified example. [Figure 9] 10A and 10B are diagrams illustrating the output of a sensor of an inspection unit and a printing surface contact roller according to a modified example. [Figure 10] 10A and 10B are diagrams illustrating outputs from sensors of an inspection unit according to another modified example. [Figure 11] FIG. 10 is a schematic configuration diagram of a printing device according to another modified example. [Figure 12]10 is a diagram showing the arrangement of the printing surface contact roller and the sensor of the inspection unit according to the modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a printing device to which the present invention is applied, and FIG. 2 is a schematic block diagram showing the same printing device.

[0009] The printing device 10 includes a transport unit 20 that transports the print medium B along a predetermined transport path from a feed roller 21 to a take-up roller 22. Along this transport path, a support unit 40 is installed to support the print medium B transported by the transport unit 20, and a printing unit 30 is installed to form an image by ejecting liquid from nozzles in a print head onto one side of the print medium B supported by the support unit 40. The printing unit 30 forms an image by ejecting liquid onto one side of the print medium B. The print head of the printing unit 30 may be a serial print head that ejects liquid while reciprocating across the print medium B, or a line head that is installed intersecting the transport direction of the transport path of the print medium B and ejects liquid across the width of the printing area. The support unit 40 also includes a platen that supports the print medium B transported by the transport unit 20. The platen may be a drum-type platen or a flat-type platen, but is not limited thereto. The printing unit 30 ejects liquid onto one side of the roll-shaped print medium B supported by the support unit 40. In FIG. 1, the liquid is ejected onto the surface of a horizontal platen.

[0010] This printing device 10 prints by ejecting a liquid onto a roll-shaped printing medium B, but the liquid must be properly fixed to the printing medium B before it is taken up by the take-up roller 22. "Fixed" refers to a state in which the liquid is not transferred from the printing medium B to something else, such as when water-based liquid ink dries or when UV light-curable ink solidifies. This printing device 10 is equipped with a fixing unit 50 that includes a drying oven 51 that dries the water-based liquid ink using heat rays and warm air from a heat source. In other words, this fixing unit 50 fixes the liquid that was ejected by the printing unit 30 and adhered to one side along the transport path. Drying using only blown air, rather than warm air, is also possible.

[0011] As described above, in the printing apparatus 10, the fixing unit 50 has the drying oven 51 as a drying unit that dries the liquid by at least one of blowing air and heating.

[0012] The transport unit 20 ejects liquid only onto the surface of the print medium B supported by the support unit 40 of the printing unit 30. After transporting the print medium B horizontally with its front surface facing upward, the transport unit 20 abuts a roller (not shown) against the back surface of the print medium B, changes the transport direction downward by approximately 90 degrees, and then abuts a roller (not shown) against the back surface of the print medium B again, changes the transport direction by approximately 90 degrees, and sends the print medium B into the drying oven 51 through the entrance / exit 51a. Because the roller abuts the back surface of the print medium B and changes the transport direction by 90 degrees twice, the print medium B is transported into the drying oven 51 with the printed side facing downward. Note that in this embodiment, the entrance / exit 51a serves as both an exit and an entrance, but the exit and entrance may be located in separate locations.

[0013] Within the drying oven 51, a guide member 51b is arranged to make a revolution within the drying oven 51 while contacting the backside of the printing medium B. Making a revolution means that the printing medium B is initially facing downward, but as it makes a revolution it is turned upside down, so that the front side faces upward, and is transported toward the entrance / exit 51a of the drying oven 51. A heater and a fan are arranged within the drying oven 51, and the fan circulates air heated by the heater, causing hot air to circulate within the drying oven 51. As the printing medium B makes a revolution within the drying oven 51 while its backside is in contact with the guide member 51b, the liquid that has landed on the surface of the printing medium B dries and becomes fixed during this time.

[0014] Near the exit from the entrance / exit 51a of the drying oven 51, there is installed a print surface contact roller 23 that comes into contact with the surface of the print medium B and changes the transport direction upward. After printing, it is this print surface contact roller 23 that the surface of the print medium B comes into contact with for the first time. The surface of the print surface contact roller 23 is white anodized, and when it is not dirty, it has high reflectivity, high detection brightness, and flat characteristics.

[0015] Since the print medium B has passed through the fixing unit 50, the liquid on the surface of the print medium B should have dried and fixed, and therefore would not be transferred even when it comes into contact with the print surface contact roller 23. After that, the print medium B travels along a predetermined transport path in the transport unit 20, goes around the outside of the drying oven 51, and is then taken up by the take-up roller 22. During this time, there are multiple rollers that come into contact with the surface of the print medium B.

[0016] In this way, the conveyance path has a plurality of rollers that come into contact with the print surface downstream of the fixing unit 50.

[0017] FIG. 3 is a schematic diagram showing the print surface contact roller in the transport section and the inspection section. A line sensor 61 serving as a sensor in the inspection unit 60 is disposed facing the printing surface contact roller 23, with which the surface of the print medium B first comes into contact after exiting the entrance / exit 51a of the drying oven 51. The line sensor 61 is configured with a row of light-receiving elements arranged in the longitudinal direction of the printing surface contact roller 23, and each light-receiving element outputs an electrical signal corresponding to the brightness of the surface of the printing surface contact roller 23 it faces. In addition, to enable the light-receiving elements to correctly detect the brightness of the surface of the printing surface contact roller 23, a light source 62 is disposed that shines illumination light toward the longitudinal direction of the printing surface contact roller 23, and the light is irradiated onto the surface of the printing surface contact roller 23, and the line sensor is installed at an angle where the reflected light enters. The printing surface contact roller 23 constitutes part of the transport unit 20 and, in this embodiment, also constitutes part of the inspection unit 60.

[0018] In this way, the inspection unit 60 inspects the fixing state of the liquid adhering to one side of the print medium B that has passed through the fixing unit 50, and the transport unit 20 has a print surface contact roller 23 that is arranged downstream of the fixing unit 50 on the transport path and comes into contact with one side of the print medium B. The inspection unit 60 also has a line sensor 61 that inspects the state of the circumferential surface of the print surface contact roller 23.

[0019] The inspection unit 60 inspects the condition of the circumferential surface of the printing surface contact roller 23, which is located downstream of the fixing unit 50 on the transport path and is the most upstream of the plurality of printing surface contact rollers. In this embodiment, the inspection unit 60 is preferably located opposite the print surface contact roller 23, which is the first roller that comes into contact with the surface of the print medium B. However, depending on installation convenience, it can also be located opposite the second or subsequent print surface contact rollers 23. When making a judgment using the first print surface contact roller 23, it is possible to make the judgment and stop the process immediately after the drying device where the print medium B is fixed, minimizing the number of defective rollers. It also minimizes the number of dirty rollers that need to be cleaned.

[0020] Figures 4 and 5 show diagrammatically the print surface contact roller and the sensor output. 4 shows a normal state where no fixing failure has occurred, in which the liquid adhering to the surface of print medium B is fixed normally and does not transfer even when it comes into contact with the surface of print surface contact roller 23 as it is transported along the transport path. In other words, print surface contact roller 23 remains white, and when illuminated by light source 62, line sensor 61, which receives reflected light, outputs an electrical signal that is generally flat and corresponds to a high brightness.

[0021] Thus, the inspection unit 60 has a light source 62 arranged along the longitudinal direction of the printing surface contact roller 23, and a line sensor 61 arranged along the longitudinal direction of the printing surface contact roller 23 and detecting reflected light that is emitted from the light source 62 and reflected by the peripheral surface. 5 shows an abnormal state where poor fixing has occurred, in which the liquid adhering to the surface of print medium B is not sufficiently fixed, and as it is transported along the transport path, some of it is transferred when it comes into contact with the surface of print surface contact roller 23. This causes the surface of print surface contact roller 23, which was white, to become dirty, and when illuminated by light source 62, line sensor 61, which receives the reflected light, outputs an electrical signal that is not uniform and indicates reduced brightness in places.

[0022] The control unit 70 controls each part of the printing device 10 to perform printing. In addition to controlling normal printing, the control unit 70 monitors the fixing state based on the output of the inspection unit 60 in parallel with various controls. As described above, if the output of the line sensor 61 is generally flat and indicates high brightness, it can be determined that the fixing state is good. On the other hand, if the output of the line sensor 61 is not flat and indicates low brightness in some areas, it can be determined that the fixing state is poor. The function that performs this judgment process is called the judgment unit 71. In other words, it constantly monitors the detected brightness distribution, and if any areas where brightness drops occur, it determines that insufficient drying is due to a drop in sensor output. The threshold value is adjusted in advance.

[0023] In this way, the control unit 70 has a determination unit 71 that determines the fixation state of the liquid attached to one side of the print medium B based on the output of the line sensor 61. This determination unit 71 constitutes a part of the inspection unit 60. If an insufficiently dried printed surface comes into contact with the roller, ink stains will adhere to it, and color will appear, reducing reflectivity and reducing the detected brightness only in the colored areas. The standard for determining whether something is good or bad is to quantify the difference from the normal state and see if the brightness change exceeds a preset threshold. In that case, a fixing failure error will be issued and printing will be stopped. In this embodiment, the control unit 70 realizes the function of the determination unit 71 in the inspection unit 60, but the inspection unit 60 can also be configured so that an independent determination unit 71 detects fixing defects based on the output of the line sensor 61. In other words, the inspection unit 60 can be realized appropriately by hardware or software.

[0024] FIG. 6 shows a flow chart corresponding to the control program. The control unit 70 executes this flowchart as the function of the determination unit 71. When printing starts in step S100, the control unit 70 acquires the output of the line sensor 61 in step S110 and determines whether the output of the line sensor 61 is flat and bright in step S120. As described above, if the output is flat and bright, the fixing state is determined to be normal, and the process ends. However, if the output is not flat and bright, the determination unit 71 issues a notification of poor fixing in step S130. The control unit 70 then controls the notification unit 80 to issue a notification. The notification may be any method that draws the operator's attention, such as an audible alarm or a red light. In addition to issuing the notification, the control unit 70 also stops printing in step S140. The printing is stopped for the transport unit 20, the printing unit 30, the support unit 40, the drying oven 51 of the fixing unit 50, and the like. Continuing operation with poor fixing results in soiling the conveying rollers of the conveying unit 20, and waste such as continuing to output unusable printed materials can be prevented.

[0025] As described above, the printing device 10 has a notification unit 80, and the determination unit 71 uses the notification unit 80 to provide notification in response to the output of the line sensor 61. Furthermore, when the output of the line sensor 61 indicates that fixing is insufficient, the determination unit 71 stops the transport of the print medium B by the transport unit 20 and stops the formation of an image by the printing unit 30.

[0026] Furthermore, it is also possible to give step-by-step notifications according to the degree of fixation even before the toner becomes completely defective.

[0027] As described above, the printing device 10 has the following features. 1) The device is equipped with a mechanism for detecting changes in the reflective brightness of the print surface contact roller 23 that contacts the print surface at the exit of the drying oven 51, which is the drying device, and determining whether the drying is insufficient. 2) It is equipped with a function that stops printing and issues an alert when insufficient fixing (insufficient drying) is detected.

[0028] Furthermore, since the influence of transfer due to insufficient fixing is monitored by monitoring the surface condition of the roller in contact with the printing surface, there is no need for a pre-defined image pattern, and the system can be applied in any situation.

[0029] FIG. 7 shows a modified example of the inspection unit, and FIGS. 8 and 9 show the sensor output and printing surface contact roller of the inspection unit according to the modified example. In the above-described embodiment, the line sensor 61 detects the reflective brightness of the surface of the printing surface contact roller 23 , but in this modified example, the printing surface contact roller 23 is photographed by a CCD camera element 63 .

[0030] Figure 8 shows a normal state where no fixing problems have occurred, in which the liquid adhering to the surface of the print medium B is fixed normally and does not transfer even when it comes into contact with the surface of the print surface contact roller 23 as it is transported along the transport path. In other words, the print surface contact roller 23 remains white, and the image captured by the CCD camera element 63 remains almost white. Although there are some areas with different brightness levels, by taking the average value at each position along the length of the print surface contact roller 23, image data that is generally flat and corresponds to high brightness can be obtained. In the case of image data, it may also be obtained as a density value. In other words, the density value is generally low.

[0031] On the other hand, Figure 9 shows an abnormal state where poor fixing has occurred, in which the liquid adhering to the surface of the print medium B is not sufficiently fixed, and as it comes into contact with the surface of the print surface contact roller 23 as it is transported along the transport path, some of the liquid is transferred. This causes the white surface of the print surface contact roller 23 to become dirty, and the brightness of the image data captured by the CCD camera element 63 is not uniform, resulting in image data that shows reduced brightness in places. In other words, the data has high density values ​​in some areas.

[0032] Instead of step S110, image data captured by the CCD camera element 63 is acquired, and based on this image data, step S120 determines whether the image is flat and high brightness, i.e., whether the density value is low overall, and branching processing is performed. If the surface of the printing surface contact roller 23 becomes dirty with the transferred liquid, a region IL with low density values ​​will appear in part of the image data. Note that the image data may be binarized for easier processing.

[0033] FIG. 10 is a diagram showing the output of the sensor of the inspection unit according to another modified example. In this modified example, the determination is based on the color output of the CCD camera element 63 shown in Fig. 7. When the surface of the print surface contact roller 23 becomes dirty, the color distribution changes from CL1, which is a normal state where no fixing problems have occurred, to CL2, and the fixing state is determined from the color change.

[0034] FIG. 11 is a schematic diagram showing the configuration of a printing device according to another modified example. This printing device 110 ejects UV light curable ink as a liquid from the nozzles of the print head 130, and fixes it by irradiating it with ultraviolet light from an ultraviolet light source 150 located downstream. In addition to colored UV light curable ink, transparent ink is also available.

[0035] As described above, in the printing apparatus 110, the UV light curable ink liquid is an ultraviolet curable ink, and the fixing unit includes an ultraviolet light source 150 as an ultraviolet irradiation unit that irradiates the ultraviolet curable ink with ultraviolet light.

[0036] FIG. 12 is a diagram showing the layout of the printing surface contact roller and the sensor of the inspection unit according to this modified example. Illumination light is projected from light source 162 onto print surface contact roller 123, which is the first roller to come into contact with the surface of print medium B downstream of ultraviolet light source 150, which serves as the fixing unit, and first line sensor 161a receives the directly reflected light. A separator 164 limits the light receiving range of first line sensor 161a so that it can receive only the directly reflected light. Second line sensor 161b and third line sensor 161c face print surface contact roller 123 at positions where they can receive scattered light other than the directly reflected light.

[0037] When the transparent UV light curable ink is properly fixed by the ultraviolet light source 150, it solidifies on the surface of the print medium B. Therefore, the UV light curable ink is not transferred to the print surface contact roller 123. Therefore, even if illumination light from the light source 162 is irradiated onto the print surface contact roller 123, the directly reflected light is incident on the first line sensor 161a, and almost no scattered light is received by the second line sensor 161b and the third line sensor 161c.

[0038] However, if the transparent UV light curable ink is not fixed properly, it will not completely solidify on the surface of the print medium B, and the UV light curable ink will end up being transferred to the print surface contact roller 123. Because the transfer is often not uniform, when illumination light from the light source 162 is irradiated onto the print surface contact roller 123, it is scattered by the mirror-like surface of the print surface contact roller 123. Therefore, although some of the light is directly reflected and incident on the first line sensor 161a, much of the scattered light also enters the second line sensor 161b and the third line sensor 161c. Therefore, by acquiring the outputs of the second line sensor 161b and the third line sensor 161c, it is possible to determine whether the ink is fixed properly, even if it is a transparent color.

[0039] Of course, if the ink is a colored ink that is not transparent and has poor fixing properties and is transferred to the surface of the printing surface contact roller 123, the first line sensor 161a, which receives directly reflected light, can detect a change in brightness, making it possible to determine the fixing state. It goes without saying that the present invention is not limited to the above-described embodiments.

[0040] - Applying mutually replaceable components and configurations disclosed in the above embodiments by appropriately changing their combinations. Although not disclosed in the above embodiments, members and configurations that are publicly known and can be mutually substituted for the members and configurations disclosed in the above embodiments may be appropriately substituted, and their combinations may be changed and applied. Although not disclosed in the above embodiments, members and configurations may be substituted by those skilled in the art based on publicly known techniques as substitutes for the members and configurations disclosed in the above embodiments, and the combinations may be changed and applied. is disclosed as one embodiment of the present invention. [Explanation of symbols]

[0041] 10...printing device, 20...conveying section, 21...feeding roller, 22...winding roller, 23...printing surface contact roller, 30...printing section, 40...supporting section, 50...fixing section, 51...drying furnace, 51a...entrance / exit, 51b...guide member, 60...inspection section, 61...line sensor, 62...light source, 63...CCD camera element, 70...control section, 71...determination section, 80...alarm section, 110...printing device, 123...printing surface contact roller, 130...printing head, 150...ultraviolet light source, 161a, 161b, 161c...line sensor, 162...light source, 164...separator.

Claims

1. a transport unit that transports the print medium along a predetermined transport path; a support portion that supports the print medium; a printing unit that ejects a liquid onto one surface of the printing medium supported by the support unit to form an image; a fixing unit that fixes the liquid ejected by the printing unit and attached to the one surface, the fixing unit being located midway along the conveying path; an inspection unit that inspects a fixing state of the liquid attached to the one surface of the print medium that has passed through the fixing unit, the transport unit has a print surface contact roller that is disposed downstream of the fixing unit in the transport path and that contacts the one surface, The inspection unit a sensor for inspecting the condition of the peripheral surface of the printing surface contact roller; a determination unit that determines a fixation state of the liquid attached to one surface of the printing medium based on an output of the sensor.

2. A notification unit is provided, The printing apparatus according to claim 1 , wherein the determining unit makes a notification using the notifying unit in response to an output from the sensor.

3. The printing device according to claim 1 or 2, characterized in that when fixing is insufficient according to the output of the sensor, the determination unit stops the transport of the printing medium by the transport unit and stops the formation of an image by the printing unit.

4. the conveying path includes a plurality of print surface contact rollers downstream of the fixing unit, The printing device according to claim 1 or 2, characterized in that the inspection unit inspects the condition of the circumferential surface of the printing surface contact roller located most upstream of the plurality of printing surface contact rollers, downstream of the fixing unit on the transport path.

5. The inspection unit 3. The printing device according to claim 1, further comprising: a light source arranged along the longitudinal direction of the printing surface contact roller; and a line sensor as the sensor arranged along the longitudinal direction of the printing surface contact roller, which detects light emitted from the light source and reflected by the peripheral surface.

6. 3. The printing apparatus according to claim 1, wherein the fixing unit is a drying unit that dries the liquid by at least one of blowing air and heating.

7. the liquid is an ultraviolet curable ink, 3. The printing apparatus according to claim 1, wherein the fixing unit is an ultraviolet irradiating unit that irradiates the ultraviolet curable ink with ultraviolet light.

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