Image forming apparatus and method for controlling the image forming apparatus

Abstract

To provide an image forming apparatus that is able to prevent nonuniform drying of a recording medium.SOLUTION: An image forming apparatus 1 comprises: an ink ejection unit 30 that ejects ink to a recording medium 70; a first heating unit 40 that is provided on a downstream side of a path from the ink ejection unit 30 and heats the ink on the recording medium 70 in a width direction of the recording medium 70 at a predetermined heating strength; a measuring unit 50 that is provided on a downstream side of the path from the first heating unit 40 and measures temperatures of a plurality of regions R1 to Rn of the recording medium 70 in the width direction; a second heating unit 60 that is provided on a downstream side of the path from the measuring unit 50 and capable of setting an intensity of the ink for each of the plurality of regions R1 to Rn; and a setting unit that sets a heating intensity of the second heating unit 60 for each of the plurality of regions R1 to Rn on the basis of the temperature information of a plurality of regions R1 to Rn. The second heating unit 60 heats the ink at the heating intensity set by the setting unit.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus and a method for controlling an image forming apparatus. [Background technology]

[0002] Inkjet type image forming apparatuses have been known in the art. For example, Japanese Patent Application Laid-Open No. 2016-112808 (Patent Document 1) discloses an image forming apparatus including a laser drying device that dries ink droplets.

[0003] The laser drying device of Patent Document 1 creates a laser irradiation profile based on the temperature characteristics of the droplets measured by a temperature sensor, whereby the temperature of the droplets is maintained within a range of equal to or higher than the inflection temperature and lower than the boiling temperature at which the droplets boil, after the temperature of the droplets reaches or exceeds the inflection temperature at which the droplets begin to rise and inflection due to laser irradiation. The laser drying device uses the created irradiation profile to control a drying means having a plurality of laser light sources arranged two-dimensionally.

[0004] In this way, the laser drying device of Patent Document 1 irradiates the ink on the paper with a laser within a range of above the inflection temperature and below the boiling temperature at which the droplets boil, thereby preventing the ink from scattering and preventing the water in the ink from remaining on the paper without evaporating. In other words, Patent Document 1 improves the drying efficiency of the ink while maintaining the quality of the generated image. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-112808 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, only the temperature change in the paper transport direction is measured. Therefore, the generated profile only considers the temperature change in the transport direction. However, the amount of ink in the paper width direction, which is perpendicular to the transport direction, is not uniform. Therefore, Patent Document 1 cannot prevent uneven drying of the paper.

[0007] The present disclosure has been made in consideration of the above problems, and its purpose is to provide an image forming apparatus and a control method for an image forming apparatus that are capable of preventing uneven drying of recording media such as paper. [Means for solving the problem]

[0008] The image forming apparatus of the present disclosure includes an ejection means for ejecting ink onto a recording medium transported along a predetermined path, a first heating means provided downstream of the path from the ejection means for heating the ink on the paper in a width direction of the recording medium perpendicular to the transport direction of the recording medium at a predetermined heating intensity, a measuring means provided downstream of the path from the first heating means for measuring the temperature of multiple regions of the paper in the width direction, a second heating means provided downstream of the path from the measuring means for setting the heating intensity of the ink for each of the multiple regions, and a setting means for setting the heating intensity of the second heating means for each of the multiple regions based on information on the temperatures of the multiple regions. The second heating means heats the ink at the heating intensity set by the setting means.

[0009] The control method of the image forming apparatus disclosed herein includes the steps of ejecting ink onto a recording medium transported along a predetermined path, heating the ink on the recording medium in a width direction of the recording medium perpendicular to the transport direction of the recording medium after ejecting the ink at a predetermined heating intensity, measuring the temperature of multiple regions of the recording medium in the width direction after heating, setting the heating intensity of the ink for each of the multiple regions based on information on the temperatures of the multiple regions after the measurement, and heating the ink in the multiple regions at the set heating intensity. Effect of the Invention

[0010] According to the present disclosure, it is possible to prevent uneven drying of paper. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1. [Diagram 2] FIG. 2 is an enlarged view showing a main part of the image forming apparatus. [Diagram 3] It shows the state in which droplets of ink are ejected to form an image on paper. [Figure 4] FIG. 4 is a diagram showing the temperature distribution in the paper area shown in FIG. 3. [Diagram 5] 6 is a diagram showing the relationship between the amount of ink and the temperature measured by a temperature sensor. [Figure 6] FIG. 11 is a diagram showing the relationship between the temperature difference and the second heating intensity. [Figure 7] FIG. 11 is a diagram showing the relationship between the ink amount and the temperature difference for black ink and color inks separately. [Figure 8] FIG. 11 is a diagram showing the relationship between the temperature difference and the second heating intensity, separately for black ink and color ink. [Figure 9] FIG. 11 is a diagram showing the relationship between the temperature difference and the second heating intensity, taking into account the characteristics of both black ink and color ink. [Figure 10] 4 is a diagram for explaining a method for setting a second heating intensity for the paper region shown in FIG. 3. FIG. [Figure 11] FIG. 2 is a diagram illustrating a hardware configuration of an image forming apparatus. [Figure 12] 4 is a flow diagram for explaining the flow of a process executed in the image forming apparatus under the control of a control unit. FIG. [Figure 13] 11 is a graph showing the relationship between the amount of ink and the temperature difference. [Figure 14] FIG. 11 is a diagram showing the relationship between the temperature difference and the second heating intensity. [Figure 15]FIG. 11 is a diagram showing the relationship between the temperature difference and the second heating intensity, taking into account the characteristics of both black ink and color ink. [Figure 16] FIG. 1 is a diagram illustrating an image forming apparatus equipped with an infrared ray shielding member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The image forming apparatus in each embodiment will be described below with reference to the drawings. In the embodiments described below, the same or corresponding parts are given the same reference numbers, and duplicate descriptions may not be repeated. In addition, in the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present disclosure is not necessarily limited to the numbers, amounts, etc., unless otherwise specified.

[0013] In the drawings, the dimensions are not shown according to the actual ratio, but in some places the ratio is changed so that the structure can be clearly seen in order to facilitate understanding of the structure. Note that the various modified examples described below may be appropriately and selectively combined.

[0014] Although the image forming apparatus will be described below as a color printer, the image forming apparatus is not limited to a color printer, and may be, for example, a monochrome printer.

[0015] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1. As shown in FIG.

[0016] 1, the image forming apparatus 1 is an inkjet type image forming apparatus. The image forming apparatus 1 includes a control unit 10, a storage unit 20, an ink ejection unit 30, a first heating unit 40, a measurement unit 50, a second heating unit 60, a paper feed roll 80, an ejection roll 90, and a transport roller 100.

[0017] The control unit 10 is communicatively connected to the transport roller 100, the ink ejection unit 30, the first heating unit 40, the measurement unit 50, and the second heating unit 60. The control unit 10 controls the operations of the transport roller 100, the ink ejection unit 30, the first heating unit 40, and the second heating unit 60. The control unit 10 has a setting unit 11 that sets the heating intensity of the second heating unit 60.

[0018] The control unit 10 drives a conveying motor (not shown) to control the rotation of conveying rollers 100 connected to the conveying motor via a mechanism such as gears. Paper 70, which is a long continuous sheet of paper, is wound around a paper feed roll 80. The paper 70 is conveyed in the direction of arrow A1 as the conveying rollers 100 rotate. The paper 70 is conveyed to discharge rollers 90 as the conveying rollers 100 rotate, and is taken up by the discharge rollers 90.

[0019] The ink ejection unit 30 ejects ink onto the paper 70 transported along a predetermined path (hereinafter also referred to as the "paper transport path"). The ink ejection unit 30 includes a head drive unit 31 and a print head 32. The print head 32 includes four print heads 32C, 32M, 32Y, and 32K corresponding to four colors, cyan (C), magenta (M), yellow (Y), and black (K).

[0020] The control unit 10 controls the operation of the ink ejection unit 30 based on color information for each pixel of the image contained in the image data stored in the storage unit 20. The control unit 10 controls the head drive unit 31. The head drive unit 31 drives the print head 32 connected to the head drive unit 31 according to the ink droplet ejection timing instructed by the control unit 10. This causes ink droplets to be ejected from the print head 32. As a result, an image based on the image data is formed on the paper 70.

[0021] The first heating section 40 heats the ink on the paper 70 with a predetermined heating intensity. The first heating section 40 is an infrared ray irradiation device. The first heating section 40 is, for example, an infrared lamp. The first heating section 40 irradiates the paper 70 with infrared rays.

[0022] The control unit 10 sends an operation instruction to the first heating unit 40. When the first heating unit 40 receives an instruction to emit light from the control unit 10, it irradiates infrared rays toward the paper 70 (more specifically, the image forming surface on which an image is formed). When the first heating unit 40 receives an instruction to stop emitting light from the control unit, it stops irradiating infrared rays.

[0023] The measurement unit 50 measures the temperature of the paper 70 onto which the ink has been ejected. The measurement unit 50 outputs the measurement result to the control unit 10. The measurement unit 50 is a temperature sensor that measures the surface temperature of the paper using a non-contact method, such as a radiation thermometer. In this example, the measurement unit 50 is a line sensor.

[0024] The second heating section 60 heats the ink on the paper 70 after the measurement by the measurement section 50. In this example, the second heating section 60 is an ultraviolet ray irradiation device that irradiates an ultraviolet ray laser.

[0025] In this manner, in the image forming apparatus 1, a first heating process is performed by the first heating section 40, and a second heating process is performed by the second heating section 60. In the following, the first heating process is also referred to as "first heating", and the second heating process is also referred to as "second heating". The heating intensity of the first heating is also referred to as "first heating intensity", and the heating intensity of the second heating is also referred to as "second heating intensity".

[0026] FIG. 2 is an enlarged view showing the main parts of the image forming apparatus 1. As shown in FIG.

[0027] 2, the ink ejection unit 30 ejects ink onto the paper 70. In detail, the ink ejection unit 30 ejects cyan ink droplets 39C, magenta ink droplets 39M, yellow ink droplets 39Y, and black ink droplets 39K based on instructions from the control unit 10.

[0028] The first heating unit 40 is provided downstream of the paper transport path from the ink ejection unit 30. The first heating unit 40 heats the ink on the paper 70 with a predetermined heating intensity at least in the paper width direction (Y-axis direction) perpendicular to the paper transport direction (arrow A1 direction, X-axis positive direction).

[0029] Specifically, the first heating section 40 irradiates a predetermined range W across the paper width direction and the paper transport direction with infrared rays 49. The first heating section 40 irradiates the paper 70 with substantially uniform infrared rays 49 over the predetermined range W. The first heating section 40 uniformly heats the predetermined range W of the paper 70 with infrared rays 49.

[0030] The measurement unit 50 is a temperature sensor device in which a plurality of temperature sensors 51 are arranged in the paper width direction. The measurement unit 50 is provided downstream of the paper transport path from the first heating unit 40. The measurement unit 50 measures the temperature of a plurality of regions R1, R2, R3, ..., Rn of the paper 70 in the paper width direction. The measurement unit 50 measures the temperature of a plurality of regions R1, R2, R3, ..., Rn by a plurality of temperature sensors 51. One temperature sensor 51 measures the temperature of one region. The measurement unit 50 outputs information on the temperature measured in the plurality of regions R1, R2, R3, ..., Rn to the control unit 10. In the following, for convenience of explanation, any one of the plurality of regions is also referred to as "region Ri". In this example, n is a natural number equal to or greater than 4. i is a natural number equal to or greater than 1 and equal to or less than n.

[0031] The second heating section 60 is provided downstream of the paper transport path from the measurement section 50. The second heating section 60 is capable of heating the ink in the above-mentioned multiple regions R1, R2, R3, ..., Rn with different heating intensities.

[0032] The second heating section 60 is a laser array in which a plurality of laser elements 61, each of which oscillates a laser beam 69, are arranged in the paper width direction. The second heating section 60 includes a switching element (not shown) that controls the on and off of each laser element 61. The second heating section 60 controls the pulse duty ratio by driving the switching element based on an instruction from the control section 10. This makes it possible to adjust the irradiation intensity (irradiation energy) of the laser beam 69 irradiated from the laser element. That is, in the image forming apparatus 1, the heating intensity by the second heating section 60 can be adjusted.

[0033] Specifically, the setting unit 11 of the control unit 10 sets the heating intensity of the second heating unit 60 for each of the multiple regions Ri based on the information on the measured temperatures of the multiple regions Ri. Specifically, the setting unit 11 adjusts the irradiation intensity of the multiple laser elements 61 based on the information on the temperatures of the multiple regions Ri. The adjustment of the irradiation intensity will be described later in detail.

[0034] Fig. 3 shows a state in which an image G is formed on a sheet of paper 70 by ejecting ink droplets 39C, 39M, 39Y, and 39K. In the state shown in Fig. 3, the image G is being heated by the first heating section 40. In other words, the first heating of the image G has been completed.

[0035] The measurement unit 50 measures the temperatures of a plurality of regions Ri in the paper width direction of the image G. Hereinafter, the region of the paper 70 measured by the measurement unit 50 at an arbitrary timing is referred to as a "paper region Q."

[0036] The paper area Q is a rectangle with its longitudinal direction being the paper width direction. Since the measurement unit 50 is a line sensor, the paper area Q is linear. As the paper 70 is transported and measurements are repeatedly performed by the measurement unit 50, multiple paper areas Q exist lined up in the paper transport direction. Each paper area Q moves sequentially in the paper transport direction. For ease of explanation, the following explanation focuses on the paper area Q shown in FIG. 3 (an area including an image of hair hanging over a person's forehead) out of the multiple paper areas Q.

[0037] The paper 70 includes a print area 71 where an image can be printed, and a margin area 72. The margin areas 72 are areas at both ends of the paper 70 in the paper width direction. The print area 71 is between the two margin areas 72. The multiple areas Ri include multiple areas R2 to Rn-1 that are included in the print area 71 of the paper 70, and areas R1 and Rn that are included in the margin area 72 of the paper 70.

[0038] As described above, the image forming apparatus 1 includes: (i) an ink ejection unit 30 that ejects ink onto a sheet of paper transported along a paper transport path; (ii) a first heating unit 40 that is provided downstream of the paper transport path from the ink ejection unit 30 and that heats the ink on the sheet of paper 70 in a paper width direction perpendicular to the paper transport direction at a predetermined heating intensity; (iii) a measurement unit 50 that is provided downstream of the paper transport path from the first heating unit 40 and that measures the temperature of multiple regions Ri of the sheet of paper 70 in the paper width direction; (iv) a second heating unit 60 that is provided downstream of the paper transport path from the measurement unit 50 and that can set the heating intensity of the ink for each of the multiple regions Ri; and (v) a setting unit 11 that sets the heating intensity of the second heating unit 60 for each of the multiple regions Ri based on information on the temperatures of the multiple regions Ri. The second heating unit 60 heats the ink at the heating intensity set by the setting unit 11.

[0039] According to this configuration, the ink can be dried taking into consideration not only the amount of ink in the paper transport direction but also the amount of ink in the paper width direction. Therefore, compared to a configuration that only takes into consideration the amount of ink in the paper transport direction, it is possible to prevent uneven drying of the paper 70. This will be explained in more detail below.

[0040] Fig. 4 is a diagram showing the temperature distribution in the paper region Q shown in Fig. 3. The temperature distribution data 201 shown in the figure is obtained by plotting the measurement results of a plurality of temperature sensors 51 in the paper width direction.

[0041] Referring to FIG. 4, blank areas including margin areas 72 do not have ink that easily absorbs light. Therefore, even when heated by first heating unit 40, the temperature of blank areas is less likely to rise than other areas. On the other hand, black (K) ink absorbs light more easily than color (C, M, Y) ink. Therefore, the temperature of the black areas rises more when heated by first heating unit 40 than color areas such as photographs or picture parts. Furthermore, the ink density of the text areas of print area 71 is lower than that of the color and black areas. Therefore, the temperature of the text areas is less likely to rise than that of the color and black areas.

[0042] As a result, the first heating causes the temperatures to increase in the order of the blank area including the margin area, the text area, the color area, and the black area. When the temperature distribution of the paper area Q is obtained in this manner, the setting unit 11 uses the temperature distribution to set the heating intensity of the second heating unit 60.

[0043] In the following, the temperature of the margin area 72 of the paper area Q is referred to as "T0". Since the image in the paper area Q changes as the paper 70 is transported, T0 also changes sequentially. The temperature of the margin area 72 can be obtained by at least one of the two temperature sensors at both ends among the multiple temperature sensors 51. The temperature of the areas of the blank paper area other than the margin area 72 (i.e., areas in the print area 71 where no ink is present) is also referred to as "T0", just like the margin area 72.

[0044] Fig. 5 is a diagram showing the relationship between the ink amount and the temperature measured by the temperature sensor 51. In detail, Fig. 5 is a graph showing the relationship between the ink amount (image density) and the difference (T-T0) between the temperature T and the temperature T0.

[0045] 5, the greater the amount of ink on the paper 70, the more light (infrared rays) the ink absorbs during the first heating process, and the easier it is for the temperature of the paper (specifically the ink) to rise. Therefore, the greater the amount of ink, the greater the temperature difference T-T0. Also, the greater the amount of ink, the greater the amount of heat required to dry the ink.

[0046] FIG. 6 is a diagram showing the relationship between the temperature difference T−T0 and the second heating intensity.

[0047] 6, data 202 indicates the relationship between the temperature difference T-T0 and the second heating intensity. The setting unit 11 sets the second heating intensity based on the data 202. More specifically, the setting unit 11 sets the second heating intensity based on the difference T-T0. Specifically, the setting unit 11 increases the second heating intensity as the difference T-T0 increases.

[0048] More specifically, the setting unit 11 sets the heating intensity of the second heating unit 60 for each of the multiple regions R2 to Rn-1 based on the respective differences between the measurement results in the multiple regions R2 to Rn-1 of the printing area 71 and the measurement results in region R1 (or region Rn) of the margin area 72.

[0049] In this way, by taking the difference T-T0 into account the temperature rise in the marginal area 72, the setting unit 11 can detect how easily the paper 70 itself warms up. Therefore, the second heating that takes differences in paper type into account is possible.

[0050] More specifically, the setting unit 11 increases the heating intensity of the second heating unit 60 in an area where the difference is larger among the multiple areas R2 to Rn-1. This configuration enables drying according to the amount of ink.

[0051] A method for controlling the second heating has been described without taking into consideration the differences in characteristics between the black (k) ink and the color (C, M, Y) inks in Fig. 5 and Fig. 6. Below, a method for controlling the second heating that takes into consideration the differences in characteristics between the black ink and the color inks will be described with reference to Figs. 7 to 10.

[0052] FIG. 7 is a diagram showing the relationship between the ink amount and the temperature difference T-T0 for black ink and color inks separately.

[0053] 7, the temperature threshold Th1 is the difference T-T0 when the maximum amount of color ink is placed on the paper 70. Black ink absorbs light more easily than color ink. Therefore, the temperature of the black ink is more likely to increase by the first heating than the color ink. Therefore, the black ink is more likely to dry than the color ink.

[0054] In this way, since the temperature of black ink increases more easily than that of color ink, the setting unit 11 determines that the area Ri where the difference T-T0 exceeds the threshold value Th1 is a black area, while the setting unit 11 determines that the area Ri where the difference T-T0 is equal to or less than the threshold value Th1 is a color area.

[0055] It should be noted that the "maximum amount of color ink" refers to the maximum amount of color ink (C, M, Y) applied by the ink ejection unit 30. The maximum amount of color ink is the maximum amount possible in terms of the control of the ink ejection unit 30. The maximum amount of color ink differs depending on the image creation control of each image forming device 1 (each model). For example, when the maximum amount of one ink is 100%, some devices have a maximum amount of color ink of 200%, while other models have a maximum amount of color ink of 250% or 300%.

[0056] For infrared rays, there is almost no difference in absorption rate due to color except for black (K). Therefore, the color combination when the maximum amount of ink is applied does not matter. For example, if the maximum amount is 200%, the combination may be 100% yellow (Y) and 100% magenta (M), 100% magenta (M) and 100% cyan (C), or 50% yellow (Y), 50% magenta (M) and 100% cyan (C). The value of the difference T-T0 in the part where such a maximum amount of color ink is placed on the paper 70 is taken as Th.

[0057] FIG. 8 is a graph showing the relationship between the difference T-T0 and the second heating intensity, separately for black ink and color ink.

[0058] Referring to Figure 8, as described above, black ink dries more easily than colored inks, so when the difference T-T0 is the same, the second heating intensity for black ink needs to be weaker than the second heating intensity for colored inks.

[0059] FIG. 9 is a diagram showing the relationship between the difference T-T0 and the second heating intensity, taking into consideration the characteristics of both black ink and color ink.

[0060] 9, data 203 shows the relationship between the difference T-T0 and the second heating intensity. In the region Ri where the difference T-T0 is equal to or smaller than the threshold Th1, the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the color curve in FIG. 8. On the other hand, in the region Ri where the difference T-T0 exceeds the threshold Th1, the setting unit 11 causes the second heating unit 60 to perform the second heating at an intensity based on the black curve in FIG.

[0061] In detail, the data 203 includes data 203c indicating the color curve in Fig. 8 and data 203b indicating a part of the black curve in Fig. 8. The image forming apparatus 1 performs the second heating using the data 203c and the data 203b which are not continuous in the portion of the threshold value Th1.

[0062] In the region Ri where the difference T-T0 is equal to or smaller than the threshold value Th1, the image forming apparatus 1 causes the second heating unit 60 to perform heating with an intensity based on the data 203c. In the region Ri where the difference T-T0 exceeds the threshold value Th1, the image forming apparatus 1 causes the second heating unit 60 to perform heating with an intensity based on the data 203b.

[0063] In this example, when the difference T-T0 exceeds the threshold value Th1, the setting unit 11 sets the second heating intensity of the second heating unit 60 to be smaller than the second heating intensity of the second heating unit 60 when the difference T-T0 is equal to the threshold value Th1. Hereinafter, a specific example will be described.

[0064] FIG. 10 is a diagram for explaining how to set the second heating intensity for the paper region Q shown in FIG.

[0065] Referring to Figure 10, the setting unit 11 adjusts the second heating intensity for the paper area Q by applying the data 203 shown in Figure 9 (data showing the relationship between the difference T-T0 and the second heating intensity) to the temperature distribution data 201 shown in Figure 4.

[0066] As described above, data 201 is data showing the temperature distribution in the paper region Q. Data 203 is data showing the relationship between the difference T-T0 and the second heating intensity. Note that in Fig. 10, the vertical and horizontal axes of data 203 are interchanged with those shown in Fig. 9.

[0067] Data 204 is data obtained by applying data 203 to data 201. Data 204 indicates the value of the second heating intensity in paper region Q in the paper width direction.

[0068] For example, referring to data 201 in Fig. 10, the measured temperature T for the blank area is T0, and therefore referring to data 203 in Fig. 10, the value of the difference T-T0 is 0. Therefore, the second heating intensity is 0.

[0069] Furthermore, referring to data 201, the measured temperature T for the color region is Tc, so referring to data 203, the value of the difference T-T0 is Tc' (=Tc-T0). Tc' is smaller than the threshold value Th1. Therefore, using data 203c of data 203, the second heating intensity is Ic.

[0070] For the black region, the measured temperature T is Tb, and therefore, when data 203 is referred to, the value of the difference T-T0 is Tb' (=Tb-T0). Tb' is greater than the threshold value Th1. Therefore, using data 203b of data 203, the second heating intensity is Ib.

[0071] For the character region, the measured temperature T is Ta, and therefore, when data 203 is referenced, the value of the difference T-T0 is Ta' (=Ta-T0). Ta' is smaller than the threshold value Th1. Therefore, using data 203c of data 203, the second heating intensity is Ia.

[0072] In this manner, the setting unit 11 generates the profile indicated in the data 204. The setting unit 11 sets the second heating intensity of the second heating unit 60 based on the profile. The setting unit 11 creates a profile for each paper region Q separately.

[0073] 3 and 10, the control unit 10 instructs the second heating unit 60 to perform second heating on the paper area Q according to the profile indicated in the data 204. When the paper area Q comes directly under the second heating unit 60, the second heating unit 60 performs second heating according to the profile. The control unit 10 causes the second heating to be performed on each paper area Q according to the profile created for each paper area Q.

[0074] As described above, the setting unit 11 judges whether each difference T-T0 is greater than the predetermined threshold value Th1. The setting unit 11 controls the heating intensity of the second heating unit 60 differently between a region among the multiple regions R2 to Rn-1 where the difference T-T0 is equal to or smaller than the threshold value Th1 and a region among the multiple regions R2 to Rn-1 where the difference T-T0 exceeds the threshold value Th1.

[0075] Furthermore, in a region Ri where the difference T-T0 is equal to or less than the threshold value Th1, the setting unit 11 sets the heating intensity of the second heating unit 60 based on data 203c indicating the relationship between the difference T-T0 and the second heating intensity of the second heating unit 60. In a region Ri where the difference T-T0 exceeds the threshold value Th1, the setting unit 11 sets the heating intensity of the second heating unit 60 based on data 203b indicating the relationship between the difference T-T0 and the second heating intensity of the second heating unit 60.

[0076] This configuration enables the ink to be dried while taking into account the characteristics of both the black ink and the color inks. Therefore, the image forming apparatus 1 can prevent uneven drying more effectively than a configuration that does not take into account the characteristics of both the black ink and the color inks.

[0077] FIG. 11 is a diagram illustrating the hardware configuration of the image forming apparatus 1. As shown in FIG.

[0078] 11, the image forming apparatus 1 includes a controller 110, a memory 120, a print head 130, a heater 140, a temperature sensor device 150, and a heater 160. The controller 110 corresponds to the control unit 10. The memory 120 corresponds to the storage unit 20. The print head 130 corresponds to the ink ejection unit 30. The heater 140 corresponds to the first heating unit 40. The temperature sensor device 150 corresponds to the measurement unit 50. The heater 160 corresponds to the second heating unit 60.

[0079] The controller 110 is communicatively connected to the memory 120, the print head 130, the heater 140, the temperature sensor device 150, and the heater 160. The controller 110 controls the operations of the print head 130, the heater 140, and the heater 160. The controller 110 reads image data and the like from the memory 120. The controller 110 obtains temperature information from the temperature sensor device 150.

[0080] FIG. 12 is a flow diagram for explaining the flow of processing executed in the image forming apparatus 1 under the control of the control unit 10. As shown in FIG.

[0081] Referring to FIG. 12, in step S1, ink (ink droplets) is ejected from the ink ejection unit 30 onto the paper 70. In step S2, the first heating unit 40 heats the ink on the paper 70 in a predetermined range W shown in FIG. 2 at a first heating intensity. In step S3, after heating by the first heating unit 40, the measurement unit 50 measures multiple regions Ri of the paper 70 in the paper width direction. In step S4, the setting unit 11 sets a second heating intensity for each of the multiple regions Ri based on information on the temperatures of the multiple regions Ri. In step S5, the second heating unit 60 heats the multiple regions Ri at the second heating intensity set for each of them.

[0082] <Modification> (1) If the above-mentioned temperature T0 is high, it can be determined that the paper is easy to heat (for example, thin paper). Therefore, the second heating intensity can be smaller than that of plain paper. If the temperature T0 is low, it can be determined that the paper is difficult to heat (for example, thick paper). Therefore, it is necessary to make the second heating intensity larger than that of plain paper. From this perspective, it is preferable to change the relationship between the difference T-T0 and the second heating intensity according to the value of T0. In other words, it is preferable that the setting unit 11 has a plurality of pieces of data 202 shown in FIG. 6 according to the value of T0. Alternatively, it is preferable that the setting unit 11 corrects the data 202 according to the value of T0.

[0083] FIG. 13 is a graph showing the relationship between the amount of ink and the difference (T−T0) between the temperature T and the temperature T0.

[0084] 13, the higher the temperature T0, the higher the temperature T. In addition, the value of the difference T-T0 also increases as the value of T0 increases. The lower the temperature T0, the lower the temperature T. In addition, the smaller the value of T0, the smaller the value of the difference T-T0.

[0085] FIG. 14 is a diagram showing the relationship between the temperature difference T−T0 and the second heating intensity.

[0086] 14, data 205 is data showing the relationship between the temperature difference T-T0 and the second heating intensity. If the temperature T0 is high, the setting unit 11 sets the second heating intensity to be weaker than that for plain paper. If the temperature T0 is low, the setting unit 11 sets the second heating intensity to be stronger than that for plain paper.

[0087] In detail, the higher the measurement result value in the regions R2 to Rn-1, the weaker the heating intensity by the second heating section 60 for the regions R2 to Rn-1. The lower the measurement result value in the regions R2 to Rn-1, the stronger the heating intensity by the second heating section 60 for the regions R2 to Rn-1. In this way, by the setting section 11 setting the second heating amount taking into consideration the value of the temperature T0, it is possible to further reduce uneven drying.

[0088] Furthermore, when using the threshold value Th1 as described above, it is preferable that the setting unit 11 has a plurality of pieces of data 203 (a set of data 203b and 203c) shown in Fig. 9 according to the value of T0. Alternatively, it is preferable that the setting unit 11 corrects the data 203 according to the value of T0. Hereinafter, an example of such a configuration will be described with reference to Fig. 15.

[0089] The setting unit 11 changes the value of the threshold Th1 depending on whether the temperature T0 is high or low. For convenience of explanation, the following description will use the threshold Th1 and thresholds Th2 and Th3 that are changed thresholds. Note that the threshold Th3 is greater than the threshold Th1. The threshold Th1 is greater than the threshold Th3.

[0090] Fig. 15 is a diagram showing the relationship between the difference T-T0 and the second heating intensity, taking into account the characteristics of both the black ink and the color ink. Fig. 15 shows data 206 based on three graphs of the data 205 in Fig. 14.

[0091] Referring to FIG. 15, when the temperature T0 is low (in the case of the top graph in FIG. 14), in the region Ri where the difference T-T0 is equal to or less than the threshold value Th2, the setting unit 11 causes the second heating unit 60 to perform heating with an intensity based on the data 262c.

[0092] When the temperature T0 is low (as in the top graph in FIG. 14), the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 262b, 262c. In the region Ri where the difference T-T0 is equal to or smaller than the threshold value Th2, the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 262c. In the region Ri where the difference T-T0 exceeds the threshold value Th2, the image forming apparatus 1 causes the second heating unit 60 to perform heating at an intensity based on the data 262b.

[0093] When the temperature T0 is high (as in the bottom graph of FIG. 14), the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 263b, 263c. In the region Ri where the difference T-T0 is equal to or smaller than the threshold value Th3, the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 263c. In the region Ri where the difference T-T0 exceeds the threshold value Th3, the image forming apparatus 1 causes the second heating unit 60 to perform heating at an intensity based on the data 263b.

[0094] When the temperature T0 is between the above two temperatures (as in the middle graph in FIG. 14), the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 261b, 261c. In the region Ri where the difference T-T0 is equal to or smaller than the threshold value Th1, the setting unit 11 causes the second heating unit 60 to perform heating at an intensity based on the data 261c. In the region Ri where the difference T-T0 exceeds the threshold value Th1, the image forming apparatus 1 causes the second heating unit 60 to perform heating at an intensity based on the data 261b.

[0095] According to this configuration, it is possible to further reduce drying unevenness compared to the configuration shown in FIG.

[0096] (2) It is preferable to prevent reflected light of the infrared rays irradiated by the first heating unit 40 from adversely affecting the measurement by the measuring unit 50. For example, it is preferable that the image forming apparatus 1 includes an infrared shielding member such as a partition plate or an optical filter that blocks infrared rays.

[0097] FIG. 16 is a diagram showing an image forming apparatus equipped with an infrared ray shielding member.

[0098] 16, the image forming apparatus 1 includes an infrared shielding member 200 between the first heating unit 40 and the measurement unit 50. The infrared shielding member 200 is disposed along the paper width direction. The infrared shielding member 200 is disposed at a height such that infrared rays reflected by the paper 70 are not received by the temperature sensor 51.

[0099] According to such a configuration, it is possible to perform temperature measurement with higher accuracy than in a configuration in which the infrared shielding member 200 is not provided.

[0100] (3) In the above, an example has been described in which the measurement unit 50 is a line sensor in which multiple temperature sensors 51 are provided in the paper width direction. However, this is not limited to this. The measurement unit 50 may be a scan-type sensor that moves in the paper width direction.

[0101] In the above description, the second heating section 60 is an example of a laser array in which a plurality of laser elements 61 are arranged in the paper width direction. However, the present invention is not limited to this. The second heating section 60 may be a scan-type heater that moves in the paper width direction.

[0102] (4) The data 202, 203, etc. may be a data table or a function.

[0103] (5) In the above, continuous paper has been described as an example of paper 70, but the paper is not limited to this. Image forming apparatus 1 may be configured to form an image on cut paper instead of continuous paper.

[0104] (6) In the above, paper has been described as an example of a recording medium, but the recording medium is not limited to this. There is no particular limit to the type of recording medium as long as it is a medium that can be printed with ink, such as film, aluminum, wood, metal, or resin.

[0105] The difference T-T0 was obtained using the temperature of the margin area 72, and based on the difference T-T0, the heating amount of the second heating was controlled, but it is not limited thereto. Instead of being limited to the margin area, the difference T-T0' may be obtained using the temperature T0' of an area where no printing is performed, and based on the difference T-T0', the heating amount of the second heating may be controlled. When the recording medium is not paper, such a method can be adopted.

[0106] (7) Referring to FIGS. 4 and 7, when the first heating is performed by the first heating unit 40, the degrees of temperature rise are different among the black area, the color area, the character area, and the blank paper area. From such differences in temperature rise, the control unit 10 can determine which of the black area, the color area, the character area, and the blank paper area each area of the paper is.

[0107] For example, the control unit 10 determines that the area Ri where the temperature exceeds the above-described threshold Th1 is the black area. Further, the control unit 10 determines that the area Ri where the temperature is equal to or lower than the threshold Th1 and exceeds a threshold Th1' (Th1' < Th1) smaller than the threshold Th1 is the color area.

[0108] The control unit 10 determines that the area Ri where the temperature is equal to or lower than the threshold Th1' and exceeds a threshold Th1'' (Th1'' < Th1') smaller than the threshold Th1 is the character area. The control unit 10 determines that the area Ri where the temperature is equal to or lower than the threshold Th1'' is the blank paper area.

[0109] In this way, by measuring the temperature of each area of the paper after the first heating by the first heating unit 40, the control unit 10 can determine which of the black area, the color area, the character area, and the blank paper area each area Ri is.

[0110] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0111] 1 Image forming apparatus, 10 Control unit, 11 Setting unit, 20 Memory unit, 30 Ink ejection unit, 31 Head drive unit, 32, 32C, 32K, 32M, 32Y Print head, 39C, 39K, 39M, 39Y Droplets, 40 First heating unit, 49 Infrared rays, 50 Measurement unit, 51 Temperature sensor, 60 Second heating unit, 61 Laser element, 69 Laser light, 70 Paper, 71 Print area, 72 Margin area, 80 Paper feed roll, 90 Discharge roll, 100 Conveyor roller, 110 Controller, 120 Memory, 130 Print head, 140, 160 Heater, 150 Temperature sensor device, 200 Infrared shielding member, 201, 202, 203, 203C, 203b, 203c, 204, 205, 206, 261b, 261c, 262b, 262c, 263b, 263c data, G image, Q paper area, R1, R2, R3, Rn area, Th1, Th2, Th3 threshold, W range.

Claims

1. an ejection means for ejecting ink onto a recording medium transported along a predetermined path; a first heating means that is provided downstream of the path from the ejection means and that heats the ink on the recording medium with a predetermined heating intensity in a width direction of the recording medium that is perpendicular to a conveying direction of the recording medium; a measuring means provided downstream of the path from the first heating means and configured to measure temperatures of a plurality of regions of the recording medium in the width direction; a second heating means provided downstream of the path from the measuring means and capable of setting a heating intensity of the ink for each of the plurality of regions; a setting means for setting a heating intensity of the second heating means for each of the plurality of regions based on information on temperatures of the plurality of regions; The second heating means heats the ink at a heating intensity set by the setting means.

2. The recording medium is paper, the plurality of regions include a plurality of first regions included in a print region of the region of the paper, and a second region included in a margin region of the region of the paper, 2. The image forming apparatus according to claim 1, wherein the setting means sets the heating intensity of the second heating means for each of the plurality of first regions based on the respective differences between the measurement results in the plurality of first regions and the measurement results in the second region.

3. 3. The image forming apparatus according to claim 2, wherein the setting unit increases the heating intensity of the second heating unit in an area where the difference is larger among the plurality of first areas.

4. The setting means is determining whether each of the differences is greater than a predetermined threshold; 4. The image forming apparatus according to claim 2, wherein the heating intensity of the second heating means is set differently in an area among the plurality of first areas where the difference is smaller than the threshold value and an area among the plurality of first areas where the difference is larger than the threshold value.

5. The setting means is In a region where the difference is equal to or less than the threshold value, the heating intensity of the second heating means is set based on first data indicating a relationship between the difference and the heating intensity of the second heating means; 5. The image forming apparatus according to claim 4, wherein in a region where the difference exceeds the threshold value, the heating intensity of the second heating means is set based on second data indicating a relationship between the difference and the heating intensity of the second heating means.

6. 6. The image forming apparatus according to claim 5, wherein when the difference exceeds the threshold value, the setting unit sets the heating intensity of the second heating unit to be smaller than the heating intensity of the second heating unit when the difference is equal to the threshold value.

7. 3. The image forming apparatus according to claim 2, wherein the setting unit reduces the heating intensity applied to the first region by the second heating unit as the measurement result in the first region increases.

8. the first heating means is an infrared ray irradiation device that irradiates infrared rays, 8. The image forming apparatus according to claim 1, further comprising a shielding means between the measuring means and the infrared ray irradiation device, for blocking the infrared ray from being incident on the measuring means.

9. 8. The image forming apparatus according to claim 1, wherein the second heating means is an ultraviolet ray irradiation device.

10. the first heating means is a lamp, 10. The image forming apparatus according to claim 1, wherein the second heating means is a laser array in which a plurality of elements, each of which emits a laser beam, are arranged in the width direction.

11. The image forming apparatus according to claim 1 , wherein the measuring unit is a sensor device having a plurality of temperature sensors arranged in the width direction.

12. A method for printing a print medium comprising: ejecting ink onto a print medium conveyed along a predetermined path by an ejection means; a step of heating the ink on the recording medium with a predetermined heating intensity in a width direction of the recording medium perpendicular to a conveying direction of the recording medium by a first heating means provided downstream of the path from the ejection means; measuring temperatures of a plurality of regions of the recording medium in the width direction by a measuring means provided downstream of the path from the first heating means; setting a heating intensity of a second heating means, the second heating means being provided downstream of the path from the measuring means and capable of setting a heating intensity of the ink for each of the plurality of regions, based on information on temperatures of the plurality of regions; heating the ink with the set heating intensity by the second heating means.

Images