JP7809966B2 - Image forming apparatus, control method for image forming apparatus, and program for controlling image forming apparatus - Google Patents

Description

This disclosure relates to control of an image forming device, and more particularly to color adjustment of an image forming device capable of color printing.

The color reproduction of output from image forming devices and other color-capable printers depends on the output environment, so color adjustments may be necessary in that environment. For convenience, such color adjustments are made by measuring and adjusting colors using an in-line sensor (colorimeter) installed in the image forming device, rather than using an external colorimeter.

Regarding measurements using inline sensors, for example, Japanese Patent Application Laid-Open No. 2016-48309 (Patent Document 1) discloses a technology that "improves image detection accuracy by calibrating one image detection unit with another image detection unit, while suppressing the generation of paper waste during calibration" (paragraph 0007). The technology disclosed in Patent Document 1 "includes a first image detection unit that detects an image on a transfer sheet that has an image formed thereon and is transported, and a second image detection unit that is separate from the first image detection unit and detects the image on the transfer sheet that has an image formed thereon and is transported. It also has a detection unit calibration mode that calibrates the first image detection unit using the image detection results from the second image detection unit. In the detection unit calibration mode, the transfer sheet transport speed during image reading by the second image detection unit is changed to a transfer sheet transport speed that is different from the normal transfer sheet transport speed during image formation. The control unit calibrates the first image detection unit based on the results of reading the same image by the first and second image detection units, thereby improving the accuracy of the image detection units without increasing paper waste during detection" (see [Abstract]).

However, measuring colors using an inline sensor (colorimeter) takes a certain amount of time. As a result, such measurements cannot be performed at the normal paper transport speed of an image forming device, and measuring color patches requires either stopping the paper transport or slowing it down. Therefore, there is a need for a way to measure color patches using an inline sensor (colorimeter) without stopping or slowing down the paper transport.

For example, Japanese Patent Laid-Open Publication No. 2018-197775 (Patent Document 2) discloses an image forming device that "appropriately performs color measurement of an adjustment image using long paper." The image forming device disclosed in Patent Document 2 "specifies a first conveying speed, which is a speed at which the transfer paper is conveyed when an image is formed and which is faster than the speed set for conveying the transfer paper when the image is read by the colorimetry unit, and a second conveying speed, which is a speed slower than the first conveying speed and set for conveying the transfer paper when the image is read by the colorimetry unit; in an adjustment mode in which the adjustment image is read using long paper as the transfer paper, the image forming unit and conveying unit are controlled to form the adjustment image on the transfer paper conveyed at the second conveying speed, and the adjustment image formed on the transfer paper is read while the transfer paper is conveyed at the second conveying speed" (see [Abstract]). According to the technology disclosed in Patent Document 2, "even when long sheets of paper are clamped and transported by both the image forming unit and the colorimetry unit, the transfer paper is transported at the same second transport speed for image formation and reading, making it possible to properly perform colorimetry of the adjustment image using the long sheets of paper" (paragraph 0023).

JP 2016-48309 A Japanese Patent Application Laid-Open No. 2018-197775

According to the technology disclosed in Patent Document 2, when the transfer paper is long, the adjustment image is extended in the sub-scanning direction so that the colorimetric unit can read the image without reducing the transfer paper transport speed. However, there is a need for technology that can measure color even when the colorimetric unit moves perpendicular to the transfer paper transport direction.

This disclosure has been made in light of the above-mentioned background, and one of its objectives is to provide technology that enables measurements to be taken without stopping or slowing down the transport of paper when the color measurement unit moves perpendicular to the paper transport direction.

An image forming apparatus according to one embodiment includes a transport mechanism for transporting a print medium, an image forming unit for forming an image on the print medium, an in-line sensor that is movable in a direction perpendicular to the transport direction of the print medium to scan one or more color patches formed on the print medium, and a control unit that controls the image forming unit to form one or more color patches on the print medium in accordance with the transport speed of the print medium and the movement speed of the in-line sensor.

In one aspect, the color patches are positioned according to information on the print medium.

In one aspect, the information includes the paper type and size.

In one aspect, the in-line sensor includes a spectrophotometer.

In one aspect, the in-line sensor further includes a trigger sensor.

In one aspect, the image forming apparatus further includes a trigger sensor that is provided separately from the in-line sensor.

In one aspect, the difference between the transport speed of the transport mechanism when forming one or more color patches on the print medium and the transport speed when forming an image other than the one or more color patches on the print medium is within a predetermined range.

In one aspect, the image forming unit further forms a trigger mark at a predetermined position relative to the position of one or more color patches.

In one aspect, the placement of the trigger mark is determined based on the transport speed of the print medium and the movement speed of the inline sensor.

In one aspect, the control unit performs color adjustment based on signals output from the in-line sensor by scanning one or more color patches.

According to another embodiment, a method for controlling an image forming apparatus is provided. The control method includes the steps of transporting a print medium, forming an image on the print medium, and moving an in-line sensor in a direction perpendicular to the transport direction of the print medium to scan one or more color patches formed on the print medium. The step of forming an image includes forming one or more color patches on the print medium in accordance with the transport speed of the print medium and the movement speed of the in-line sensor.

According to yet another embodiment, a program for controlling an image forming device is provided. The program causes the image forming device to perform the steps of transporting a print medium, forming an image on the print medium, and moving an in-line sensor in a direction perpendicular to the transport direction of the print medium to scan one or more color patches formed on the print medium. The step of forming an image includes forming one or more color patches on the print medium in accordance with the transport speed of the print medium and the movement speed of the in-line sensor.

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

1 is a diagram illustrating an external appearance of an image forming apparatus 100 according to an embodiment. FIG. 10 is a diagram illustrating an external appearance of an image forming apparatus 200 according to another embodiment. FIG. 2 is a block diagram showing an outline of the hardware configuration of image forming apparatuses 100 and 200. FIG. 1 illustrates an example of the configuration of an in-line sensor 400 according to an aspect. FIG. 10 is a diagram illustrating an example of the configuration of an in-line sensor 500 according to another aspect. 10 is a flowchart showing a part of the process executed by a CPU 310 of the image forming apparatus 100, 200. 7 is a diagram showing one manner in which patches are arranged on a long sheet of paper 700 when an inline sensor 400 is used. FIG. FIG. 4 illustrates one way in which patches may be placed on a sheet when an in-line sensor 400 is used. FIG. 10 is a diagram showing one manner in which patches are arranged on a long sheet of paper 900 when an inline sensor 500 is used. 10A and 10B are diagrams showing other ways in which patches are arranged on a long sheet of paper 1000 when an inline sensor 400 is used.

Embodiments of the present invention will now be described with reference to the drawings. In the following description, identical components are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

An overview of the image forming apparatus according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing the exterior of image forming apparatus 100 according to one embodiment. Figure 2 is a diagram showing the exterior of image forming apparatus 200 according to another embodiment. Image forming apparatus 200 can also handle printing on so-called long paper.

Referring to FIG. 1, the image forming apparatus 100 includes a paper feed unit 110, an image forming unit 120, inline scanners 130 and 140, an inline sensor 150, a paper discharge unit 160, a conveying unit 170, and a control unit 190.

The paper feed unit 110 receives a supply of paper or other printing media from an external source. The paper feed unit 110 supplies the printing media to the image forming unit 120 via the transport unit 170.

The image forming unit 120 contains toner of the colors yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 120 forms an image on the print medium based on image data generated from data provided to the image forming device 100.

The inline scanners 130 and 140 optically read the image formed on the print medium by the image forming unit 120 and output a signal corresponding to the reading result. The output signal is input to the control unit 190.

The inline sensor 150 detects color patches placed on the print medium. The detection results are sent to the control unit 190.

The paper discharge unit 160 receives the print media on which an image is formed and then discharged. The paper discharge unit 160 may be configured to receive the discarded paper in a different cassette for each job.

The transport unit 170 operates in response to commands from the control unit 190 and transports print media from the paper feed unit 110 to the paper discharge unit 160.

The control unit 190 controls the operation of the image forming apparatus 100. In one aspect, the control unit 190 is implemented by one or more processors that execute instructions.

Referring to FIG. 2, the image forming apparatus 200 includes a paper feed unit 110, an image forming unit 120, inline scanners 130 and 140, an inline sensor 150, a paper discharge unit 160, a conveying unit 170, and a control unit 190. The paper feed unit 110 includes a paper feed roller 210. The paper discharge unit 160 includes a paper discharge roller 220.

The paper feed unit 110, image forming unit 120, inline scanners 130 and 140, inline sensor 150, paper discharge unit 160, and control unit 190 of the image forming apparatus 200 perform functions similar to those performed by the paper feed unit 110, image forming unit 120, inline scanners 130 and 140, inline sensor 150, paper discharge unit 160, and control unit 190 of the image forming apparatus 100, respectively.

Furthermore, the paper feed roller 210 receives a roll of long paper prepared as a print medium. The long paper is sequentially fed out by the conveying unit 170 and taken up by the paper discharge roller 220.

The specific configuration of image forming apparatuses 100 and 200 will be described with reference to Figure 3. Figure 3 is a block diagram showing an overview of the hardware configuration of image forming apparatuses 100 and 200. Image forming apparatuses 100 and 200 include a CPU (Central Processing Unit) 310, RAM 320, a storage unit 330, an operation unit 340, a display unit 350, a communication unit 360, an image forming unit 120, and an image reading unit 370. The image reading unit 370 includes inline scanners 130 and 140 and an inline sensor 150.

CPU 310 controls the operation of image forming apparatuses 100 and 200. RAM 320 temporarily stores data received by image forming apparatuses 100 and 200 from external sources or data generated by CPU 310.

The storage unit 330 permanently stores data received by the image forming apparatuses 100 and 200 from external sources or data generated by the CPU 310. In one aspect, the storage unit 330 is implemented by a non-volatile storage device such as a hard disk drive or an SSD (Solid State Drive). In one aspect, the storage unit 330 stores various programs, including a color adjustment patch creation program, a color adjustment execution program, an inline sensor measurement program, and a color adjustment calculation program.

Operation unit 340 accepts commands input by a user of image forming apparatus 100, 200. In one aspect, operation unit 340 is implemented as a software switch such as a touch panel, or as a hardware switch such as a button or toggle switch. In another aspect, operation unit 340 may be configured as a detachable operation panel, such as a tablet terminal.

The display unit 350 displays the operation screen or status of the image forming apparatus 100, 200. The operation screen displays operating conditions, including color adjustment, density, and other printing conditions, entered by the user of the image forming apparatus 100, 200. The status of the image forming apparatus 100, 200 includes information indicating the current status of the image forming apparatus 100, 200. In one aspect, the display unit 350 is implemented as an LCD monitor or an organic EL (Electro-Luminescence) monitor. In another aspect, the display unit 350 can be implemented as a detachable monitor device, such as a tablet terminal.

The communication unit 360 communicates with a personal computer or other information and communication device that can communicate with the image forming apparatuses 100 and 200. The communication format is not particularly limited. The information and communication device sends a print command to the image forming apparatuses 100 and 200, and upon receiving the print command, the image forming apparatuses 100 and 200 execute a specified printing operation. In another aspect, the information and communication device can also function as an external monitor device that displays the status of the image forming apparatuses 100 and 200.

The image reading unit 370 measures patches placed on the print medium to adjust colors and check accuracy. In one aspect, the inline sensor 150 reads patches formed on paper on which color printing has been performed and outputs a signal corresponding to the reading result. This signal is input to the CPU 310. The CPU 310 uses this signal to adjust each color or check accuracy.

The specific configuration of the inline sensor 150 will be described with reference to Figures 4 and 5. The inline sensor 150 can move in a direction perpendicular to the paper transport direction. The inline sensor 150 measures color patches arranged on the paper in the main scanning direction.

Figure 4 shows an example of the configuration of an inline sensor 400 according to one aspect. Figure 5 shows an example of the configuration of an inline sensor 500 according to another aspect.

Referring to FIG. 4, the in-line sensor 400 includes a colorimeter 410 and a trigger sensor 420. The colorimeter 410 performs spectroscopic measurements and obtains color values (L*a*b, XYZ, density) similar to those obtained by an external colorimeter. The trigger sensor 420 detects a trigger mark that serves as the measurement reference point for the in-line sensor 400. The trigger sensor 420 moves in the same manner as the colorimeter 410, and can therefore detect trigger marks arranged in the main scanning direction.

Referring to FIG. 5, the inline sensor 500 includes a colorimeter 410. The trigger sensor 420 is arranged separately from the inline sensor 500. With this configuration, the colorimeter 410 moves perpendicular to the paper transport direction and can measure color patches arranged in the main scanning direction on the paper. On the other hand, the trigger sensor 420 is fixed to the image forming apparatus 100, 200 and does not move, so it detects trigger marks arranged at predetermined positions on the paper in the main scanning direction.

[Control Structure]
The control structure of image forming apparatuses 100 and 200 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing a part of the processing executed by CPU 310 of image forming apparatuses 100 and 200. Note that in another aspect, this processing may be realized by circuit elements or other hardware.

In step S610, CPU 310 detects that a color adjustment instruction has been issued based on the setting input provided to operation unit 340. For example, when a user of image forming apparatus 100, 200 inputs an instruction to perform color adjustment, CPU 310 begins color adjustment operation. The color adjustment instruction is issued, for example, when image forming apparatus 100, 200 starts operation, or when image forming apparatus 100, 200 finishes printing one content and before it starts printing another content. In another aspect, CPU 310 can be configured to automatically perform color adjustment at a preset timing.

In step S615, CPU 310 acquires the colors to be adjusted and the number of colors based on the setting input. For example, if a color printing instruction is input, CPU 310 may set yellow, magenta, cyan, and black as the colors to be adjusted. In other aspects, CPU 310 may select the colors specified by the user as the colors to be adjusted.

In step S620, CPU 310 acquires the paper transport speed of the output conditions. For example, CPU 310 selects a speed that corresponds to the selected print quality from multiple paper transport speeds that are prepared in advance according to the print quality. The multiple paper transport speeds are stored in memory unit 330 or RAM 320.

In step S625, the CPU 310 acquires the movement speed of the inline sensors 400, 500 in a direction perpendicular to the paper transport direction. That is, the CPU 310 calculates the speed at which the inline sensors 150 move across the paper as the print medium while it is being transported. This speed is set at least as fast as possible for the inline sensors 150 to scan across the area to be printed on the paper while the paper is being transported at the normal printing speed. In some cases, the movement speed is set to ensure the shortest time possible for the inline sensors 400, 500 to manipulate color.

In step S630, the CPU 310 calculates the main scanning direction placement rules for the patches to be measured by the inline sensors 400 and 500. For example, the CPU 310 determines whether to place the patches in a line or to place them diagonally across the printable area of the paper.

In step S635, CPU 310 determines whether the paper type is long paper. This determination is made based on instructions provided by the user of image forming apparatus 100, 200, or the type of paper feed mechanism installed in paper feed unit 110 (a cassette for sheets or a paper feed roller). If CPU 310 determines that the paper type is long paper (YES in step S635), it switches control to step S640. If not (NO in step S635), CPU 310 switches control to step S645.

In step S640, the CPU 310 acquires the size of the paper. For example, the CPU 310 acquires width information of the roll paper set on the paper feed roller 210 from a sensor (not shown) in the paper feed unit 110. In another aspect, the CPU 310 acquires the size (width information) of the paper being transported based on the long paper information set in the operation unit 340.

In step S645, CPU 310 acquires the size of the paper. For example, CPU 310 acquires the size of the paper being transported based on the type of paper cassette used in paper feed unit 110, or based on paper information set in operation unit 340.

In step S650, CPU 310 calculates the number of patches that can be placed on one sheet of paper.

In step S655, CPU 310 determines whether the adjusted colors can be placed on one sheet of paper. If CPU 310 determines that the adjusted colors can be placed on one sheet of paper (YES in step S655), it switches control to step S660.

In step S660, the CPU 310 determines the placement of patches in the main scanning direction for measurement by the inline sensors 400 and 500. For example, in the case of long paper, if the length of one printed sheet (feed amount in the transport direction) is 5 m and the width of the long paper is 1 m, the CPU 310 calculates how many scans the inline sensors 400 and 500 can perform based on the distance of the long paper in the scanning direction (= 1 m) and the operating capabilities of the inline sensors 400 and 500. For example, if the CPU 310 determines that 10 scans are possible, it may divide the printing area (e.g., 4.5 m) of the transport direction length (= 5 m) into 10 equal parts and calculate the placement interval of each color patch as 0.45 m. On the other hand, when image forming apparatus 100 transports a sheet of paper as a print medium, if CPU 310 determines, based on the width of the sheet and the scanning speed of inline sensors 400, 500, that inline sensors 400, 500 can scan eight times while a single sheet of paper is being transported, CPU 310 can determine that eight measurement patches (color patches) can be placed in the scanning direction. In this case, CPU 310 can divide the length of a single sheet of paper in the transport direction into eight equal parts and determine the position of each patch so that the eight patches are evenly spaced.

In step S665, CPU 310 divides the main scanning direction patch placement for measurement by inline sensors 400 and 500 into multiple pages and determines the placement. For example, if color adjustment is performed for each of multiple colors, CPU 310 may determine to place patches for each color on one sheet of paper.

In step S670, the CPU 310 places a trigger mark as an adjustment image corresponding to the position of the patch for measurement by the inline sensors 400 and 500.

In step S675, the CPU 310 acquires the image formation conditions and measurement conditions for color adjustment. The image formation conditions include the profile type, which is a color management condition, or the spot color table type if the adjusted color is a special color. The measurement conditions include the settings of the light source conditions (M0, M1, M2), etc.

In step S680, the CPU 310 forms an adjustment image (each patch and trigger mark) on paper based on the acquired conditions.

In step S685, the CPU 310 measures the patch of the adjustment image using the inline sensors 400 and 500 and obtains the measurement values.

In step S690, the CPU 310 calculates the adjustment value using the acquired measurement value.

In step S695, CPU 310 registers the adjustment values. For example, CPU 310 registers the adjustment values in RAM 320 or memory unit 330. After that, printing by image forming apparatuses 100 and 200 is performed with the registered adjustment values reflected.

[Example of an image for adjustment]
An example of an adjustment image will be described with reference to Figures 7 and 8. Figure 7 is a diagram showing one mode in which patches are arranged on long sheet of paper 700 when inline sensor 400 is used. Figure 8 is a diagram showing one mode in which patches are arranged on a sheet of paper when inline sensor 400 is used.

Referring to Figure 7, the long sheet of paper 700 is transported in the direction of arrow 720. The inline sensor 400 moves in the directions of arrows 710 and 711. In other words, the inline sensor 400 moves back and forth in a direction perpendicular to the direction in which the long sheet of paper 700 is transported.

In one aspect, the image forming unit 120 forms a plurality of trigger marks 730, a plurality of first color patches 740, and a plurality of second color patches 750 on the long sheet of paper 700. In the example shown in Figure 7, the trigger marks 730 and the first color patches 740 are formed in eight locations across the long sheet of paper 700.

While the long sheet of paper 700 is being transported in the direction of arrow 720, the inline sensor 400 moves in the direction of arrow 710 at a predetermined speed. This speed is set, for example, so that the inline sensor 400 can measure the first color patches 740 formed in eight locations while it travels from the left edge to the right edge of the long sheet of paper 700. When the inline sensor 400 detects the first trigger mark 730, it assumes that a color patch will appear afterwards and waits in measurement mode.

The inline sensor 400 measures the color of the first color patch 740 in the first location. The measurement value is input to the CPU 310. The inline sensor 400 continues to move according to the transport speed of the long sheet 700, and when it detects the second trigger mark 730, it waits to measure the second color patch 740. When the inline sensor 400 detects the second color patch 740, it outputs the measurement value. The inline sensor 400 measures the color of the first color patches in eight locations while moving in the direction of the arrow 710.

When the inline sensor 400 detects the trigger mark 760, it outputs a signal indicating this detection to the CPU 310. The CPU 310 detects that the inline sensor 400 has completed scanning in the first scanning direction (the direction of the arrow 710).

When the inline sensor 400 detects the trigger mark 761, it senses that scanning in the second scanning direction (the direction of arrow 711) has begun. More specifically, when the inline sensor 400 detects the trigger mark 730, it waits for the detection of an adjustment image. When the inline sensor 400 detects the second color patch 750 located in the first location, it measures the color of the second color patch 750 and outputs the measurement value to the CPU 310. Thereafter, the inline sensor 400 detects the trigger mark 730 located in the second location and further measures the color of the second color patch 750. While moving in the direction of arrow 711, the inline sensor 400 measures the color of the second color patches 750 located in eight locations and outputs the measurement value to the CPU 310.

After that, when the inline sensor 400 detects the trigger mark 770, it outputs a signal corresponding to the detection result to the CPU 310. The CPU 310 detects that measurement of the second color patch 750 in the second scanning direction (the direction of the arrow 720) has ended. Based on the measurement value and color information based on preset information, the CPU 310 determines whether the color of the image formed on the long sheet of paper 700 is the specified color. The CPU 310 can adjust the color according to the result of this determination.

When the inline sensor 400 detects trigger mark 772 following trigger mark 771, it detects that scanning for image adjustment of the long sheet of paper 700 has ended.

In other cases, the trigger mark 772 may not be formed on the long sheet of paper 700, and the third color patch may be formed in the same manner as the first color patch 740. In this case, the third color patch may be arranged in the same manner as the first color patch 740, and the inline sensor 400 may again move in the direction of the arrow 710 to measure the third color patch.

Referring to Figure 8, color adjustment using the inline sensor 400 can also be applied to sheets. Specifically, as in the example shown in Figure 7, each sheet is transported sequentially in the direction of arrow 720. The inline sensor 400 moves in the directions of arrows 710 and 711.

The first sheet 810 has trigger marks 730 and first color patches 740 formed in eight locations. Trigger marks 760 and 761 are also arranged. The second sheet 820 has trigger marks 730 and second color patches 750 formed in eight locations. Trigger marks 770, 771, and 772 are also arranged.

While the first sheet 810 is being transported in the direction of arrow 720, the inline sensor 400 moves in the direction of arrow 710 at a predetermined speed. This speed is set, for example, so that the inline sensor 400 can measure the first color patches 740 formed in eight locations while it travels from the left edge to the right edge of the sheet 810. When the inline sensor 400 detects the first trigger mark 730, it assumes that the first color patch 740 will appear thereafter and waits in measurement mode.

The inline sensor 400 measures the color of the first color patch 740 in the first location and outputs the measurement value. This measurement value is input to the CPU 310. The inline sensor 400 continues to move in accordance with the transport speed of the paper sheet 810, and when it detects the second trigger mark 730, it waits to measure the second color patch 740. When the inline sensor 400 detects the second color patch 740, it outputs the measurement value. In this way, the inline sensor 400 measures the color of the first color patches in eight locations while moving in the direction of the arrow 710.

When the inline sensor 400 detects the trigger mark 760, it outputs a signal indicating this detection to the CPU 310. The CPU 310 then detects that scanning in the first scanning direction (the direction of the arrow 710) has ended.

When the inline sensor 400 detects the trigger mark 761, it detects that scanning of the second sheet 820 in the second scanning direction (the direction of arrow 711) has begun. More specifically, when the inline sensor 400 detects the trigger mark 730, it waits for the detection of an adjustment image. When the inline sensor 400 detects the second color patch 750 located in the first location, it measures the color of the second color patch 750 and outputs the measurement value to the CPU 310. Thereafter, the inline sensor 400 detects the trigger mark 730 located in the second location and further measures the color of the second color patch 750. While moving in the direction of arrow 711, the inline sensor 400 measures the color of the second color patches 750 located in eight locations and outputs the measurement value to the CPU 310.

After that, when the inline sensor 400 detects the trigger mark 770, it outputs a signal corresponding to the detection result to the CPU 310. The CPU 310 detects that measurement of the second color patch 750 in the second scanning direction (the direction of the arrow 720) has ended. Based on the measurement value and color information based on preset information, the CPU 310 determines whether the color of the image formed on the sheet 820 is the specified color. The CPU 310 can adjust the color depending on the result of this determination.

When the inline sensor 400 detects trigger mark 772 following trigger mark 771, it detects that image adjustment has been completed for all colors.

[Other examples of images for adjustment]
Another example of the adjustment image will be described with reference to Fig. 9. Fig. 9 is a diagram showing one mode in which patches are arranged on long paper 900 when an inline sensor 500 is used.

Referring to Figure 9, the long sheet of paper 900 is transported in the direction of arrow 720. The inline sensor 500 moves in the directions of arrows 710 and 711. In other words, the inline sensor 500 moves back and forth in a direction perpendicular to the direction in which the long sheet of paper 900 is transported.

In one aspect, the image forming unit 120 forms a plurality of trigger marks 730, a plurality of first color patches 740, and a plurality of second color patches 750 on the long sheet of paper 700. In the example shown in FIG. 9, the trigger marks 730 and the first color patches 740 are formed in eight locations across the long sheet of paper 900. In this case, the trigger marks 730 are arranged in a line along the transport direction of the long sheet of paper 900. The intervals between each trigger mark 730 are, for example, equal.

When the inline sensor 500 detects the first trigger mark 730, it outputs the detection result. The detection result is sent to the CPU 310. The CPU 310 sets the operating mode of the image forming apparatuses 100 and 200 to color adjustment mode and waits to receive further signals.

When the inline sensor 500 detects the first color patch 740, it measures the color of the first color patch 740 and outputs the measurement value. The measurement value is input to the CPU 310.

While the long sheet of paper 900 is being transported in the direction of arrow 720, the inline sensor 500 moves in the direction of arrow 710 at a predetermined speed. This speed is set, for example, so that the inline sensor 500 can measure the first color patches 740 formed in eight locations while traveling from the left edge to the right edge of the long sheet of paper 900.

The inline sensor 500 measures the color of the first color patch 740 in the first location. The measurement value is input to the CPU 310. The inline sensor 500 continues to move according to the transport speed of the long sheet 900, and when it detects the second trigger mark 730, it waits to measure the second color patch 740. When the inline sensor 500 detects the second color patch 740, it outputs the measurement value. The inline sensor 500 measures the color of the first color patches in eight locations while moving in the direction of the arrow 710.

If the trigger sensor 420 does not detect the next trigger mark 730 within a set period after detecting the trigger mark 730, it outputs a signal indicating this to the CPU 310. The CPU 310 detects that the in-line sensor 500 has completed scanning in the first scanning direction (the direction of the arrow 710).

After detecting that scanning in the first scanning direction (direction of arrow 710) has ended, the inline sensor 500 waits to scan in the second scanning direction (direction of arrow 711).

When the trigger sensor 420 detects the first trigger mark 730 (ninth from the top in Figure 9) for scanning in the second scanning direction (direction of arrow 711), it outputs the detection result. The detection result is sent to the CPU 310. The CPU 310 sends a signal to the inline sensor 500 to start scanning in the second scanning direction (direction of arrow 711). More specifically, when the inline sensor 500 detects the second color patch 750 placed in the first location, it measures the color of the second color patch 750 and outputs the measurement value. The measurement value is input to the CPU 310.

The inline sensor 500 then detects the trigger mark 730 placed in the second location and further measures the color of the second color patch 750. While moving in the direction of the arrow 711, the inline sensor 500 sequentially measures the color of the second color patches 750 placed in eight locations and outputs each measurement value. Each measurement value is input to the CPU 310.

After that, if the trigger sensor 420 does not detect the next trigger mark 730 within a set period after detecting the trigger mark 730, it outputs a signal indicating this to the CPU 310. The CPU 310 detects that measurement of the second color patch 750 in the second scanning direction (the direction of the arrow 720) has ended. The CPU 310 determines whether the color of the image formed on the long sheet of paper 900 is the specified color based on the measurement values acquired so far and color information based on pre-set information. The CPU 310 can adjust the color depending on the result of this determination.

After the CPU 310 detects the completion of measurement of the second color patch 750 in the second scanning direction (the direction of the arrow 720), if the trigger sensor 420 does not detect the next trigger mark 730 within a set period of time, a signal indicating this is output to the CPU 310. The CPU 310 then detects that image adjustment of the long paper 900 has been completed.

In another aspect, after the CPU 310 detects the end of measurement of the second color patch 750 in the second scanning direction (the direction of arrow 720), when the trigger sensor 420 detects the next trigger mark 730 within a set period, it may be that the third color patch is formed in the same manner as the first color patch 740. In this case, the inline sensor 500 may again move in the direction of arrow 710 and measure the third color patch, assuming that the third color patch is arranged in the same manner as the first color patch 740.

With reference to Figure 10, another example will be described. Figure 10 is a diagram showing another way in which patches are placed on long sheet of paper 1000 when an inline sensor 400 is used. The example shown in Figure 10 is an example in which an inline scanner 140 is used as one of the trigger sensors, and trigger marks 730 placed on both ends of the long sheet of paper 1000 are detected by the inline scanner 140, and is different from the example shown in Figure 7. Note that the trigger marks 730 are also used to adjust the position of the paper.

The long sheet of paper 1000 is transported in the direction of arrow 720. The inline sensor 400 moves in the directions of arrows 710 and 711. That is, as in the example shown in Figure 7, the inline sensor 400 moves back and forth in a direction perpendicular to the direction in which the long sheet of paper 1000 is transported.

In one aspect, the image forming unit 120 forms two trigger marks 730, multiple first color patches 740, and multiple second color patches 750 on the long sheet of paper 1000. In the example shown in Figure 10, the two trigger marks 730 are formed on both ends of the long sheet of paper. The first color patches 740 are formed in eight locations across the long sheet of paper 1000.

While the long sheet of paper 1000 is being transported in the direction of arrow 720, the inline sensor 400 moves in the direction of arrow 710 at a predetermined speed. This speed is set, for example, so that the inline sensor 400 can measure the first color patches 740 formed in eight locations while traveling from the left edge to the right edge of the long sheet of paper 1000. When the inline scanner 140 detects the first trigger mark 730, it outputs the detection result. The detection result is input to the CPU 310. The CPU 310 assumes that a color patch will appear after that, notifies the inline sensor 400, and waits in measurement mode.

The inline sensor 400 measures the color of the first color patch 740 in the first location and outputs the measurement value. The measurement value is input to the CPU 310. The inline sensor 400 continues to move according to the transport speed of the long sheet of paper 700. When the inline sensor 400 detects the second first color patch 740, it outputs the measurement value. The measurement value is input to the CPU 310. In this way, the inline sensor 400 measures the color of the first color patches in eight locations while moving in the direction of the arrow 710.

When the inline sensor 400 detects the trigger mark 760, it outputs a signal indicating this detection. This signal is input to the CPU 310. Based on this signal, the CPU 310 detects that the inline sensor 400 has finished scanning in the first scanning direction (the direction of the arrow 710). The movement of the inline sensor 400 ends upon detection of the trigger mark 760. The transport of the long sheet 1000 continues. When the inline sensor 400 detects the trigger mark 761, it outputs the detection result. The detection result is input to the CPU 310. Based on this detection result, the CPU 310 detects the start of scanning in the direction of the arrow 711.

More specifically, when the inline sensor 400 detects the second color patch 750 placed in the first location, it measures the color of the second color patch 750 and outputs the measurement value. The measurement value is input to the CPU 310. Then, when the inline sensor 400 detects the second color patch 750 placed in the second location, it measures the color of the second color patch 750. While moving in the direction of the arrow 711, the inline sensor 400 sequentially measures the color of the second color patches 750 placed in eight locations and outputs each measurement value to the CPU 310.

After that, when the inline sensor 400 detects the trigger mark 770, it outputs a signal corresponding to the detection result. This signal is input to the CPU 310. Based on receiving this signal, the CPU 310 detects that measurement of the second color patch 750 in the second scanning direction (the direction of the arrow 720) has ended. Based on the measurement value and color information based on preset information, the CPU 310 determines whether the color of the image formed on the long sheet 1000 is the specified color. The CPU 310 can adjust the color based on the result of this determination.

When the inline sensor 400 detects trigger mark 772 following trigger mark 771, it detects that scanning for image adjustment of the long sheet of paper 1000 has ended.

In other cases, the trigger mark 772 may not be formed on the long sheet of paper 700, and the third color patch may be formed in the same manner as the first color patch 740. In this case, the third color patch may be arranged in the same manner as the first color patch 740, and the inline sensor 400 may again move in the direction of the arrow 710 to measure the third color patch.

The technical features disclosed above can be summarized as follows:

[Configuration 1] Image forming apparatuses 100, 200 according to one embodiment include a transport mechanism (transport unit 170) that transports print media, an image forming unit 120 that forms an image on the print media, an in-line sensor 150 that is movable in a direction perpendicular to the transport direction of the print media to scan one or more color patches formed on the print media, and a control unit (CPU 310) that controls the image forming unit to form one or more color patches on the print media in accordance with the transport speed of the print media and the movement speed of the in-line sensor.

[Configuration 2] In one aspect, the color patches are arranged according to information about the printing medium (e.g., the width of a long sheet of paper, the printing length of one sheet, the size of the sheet, etc.). The CPU 310 determines where to arrange the color patches based on this information. This information is provided as image formation data before printing begins.

[Configuration 3] In one aspect, the information includes the type and size of paper.

[Configuration 4] In one aspect, the in-line sensor includes a spectrophotometer.

[Configuration 5] In one aspect, the in-line sensor further includes a trigger sensor. Because the spectrophotometer and trigger sensor can move together, the CPU 310 can form the color patch and trigger patch in close proximity.

[Configuration 6] In one aspect, the image forming apparatus further includes a trigger sensor that is provided separately from the in-line sensor. Because the trigger sensor is provided independently of the movement of the in-line sensor, the trigger mark 730 can be formed in a location away from the position of the color patch.

[Configuration 7] In one aspect, the difference between the transport speed of the transport mechanism when forming one or more color patches on the print medium and the transport speed when forming an image other than the one or more color patches on the print medium is within a predetermined range. The predetermined range is one in which there is essentially no speed difference. Since there is no need to change the speed at which the print medium is transported to print a content image on the print medium and the speed at which the print medium is transported to print color patches for color adjustment on the print medium, there is no need to complicate the transport control of the image forming apparatuses 100 and 200.

[Configuration 8] In one aspect, the image forming unit further forms a trigger mark at a predetermined position relative to the position of one or more color patches.

[Configuration 9] In one aspect, the placement of the trigger mark is determined based on the transport speed of the print medium and the movement speed of the in-line sensor 150.

[Configuration 10] In one aspect, the control unit performs color adjustment based on a signal output from an in-line sensor by scanning one or more color patches. For example, if the color numerical value given as an image formation instruction differs from the color numerical value obtained by reading the image (color patch) actually formed on the print medium, the CPU 310 corrects the numerical value specifying the color based on the difference between these numerical values.

[Configuration 11] According to another embodiment, a control method for an image forming apparatus is provided. This control method is implemented, for example, by the CPU 310 of the image forming apparatus 100, 200. Specifically, the control method includes the steps of transporting a print medium, forming an image on the print medium, and moving an in-line sensor in a direction perpendicular to the transport direction of the print medium to scan one or more color patches formed on the print medium. The image forming step includes forming one or more color patches on the print medium in accordance with the transport speed of the print medium and the movement speed of the in-line sensor.

[Configuration 12] According to yet another embodiment, a program for controlling an image forming apparatus is provided. This program causes the image forming apparatus to carry out the steps of transporting a print medium, forming an image on the print medium, and moving an in-line sensor in a direction perpendicular to the print medium transport direction to scan one or more color patches formed on the print medium. The step of forming an image includes forming one or more color patches on the print medium in accordance with the print medium transport speed and the in-line sensor movement speed. For example, the CPU 310 can execute each of the above processing steps by loading the program stored in the storage unit 330 into the RAM 320 and executing the instructions included in the program.

In this way, the image forming apparatuses 100 and 200 according to this embodiment have inline sensors 400 and 500, which are color measurement units, that move perpendicular to the paper transport direction to measure color patches formed on the paper. This allows the inline sensors 400 and 500 to measure patches arranged in the main scanning direction without having to temporarily stop or slow down paper transport.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications that are equivalent in meaning to and within the scope of the claims.

The disclosed technical features are applicable to commercial printing machines, such as both sheet-fed printing machines and long paper (roll paper) printing machines.

100, 200 Image forming device, 110 Paper feed unit, 120 Image forming unit, 130, 140 Inline scanner, 150, 400, 500 Inline sensor, 160 Paper discharge unit, 170 Conveyor unit, 190 Control unit, 210 Paper feed roller, 220 Paper discharge roller, 320 RAM, 330 Memory unit, 340 Operation unit, 350 Display unit, 360 Communication unit, 370 Image reading unit, 410 Colorimeter, 420 Trigger sensor, 700, 900, 1000 Long paper, 710, 711, 720 Arrows, 722, 730, 760, 761, 770, 771, 772 Trigger mark, 740 First color patch, 750 Second color patch, 810, 820 Sheet of paper.

Claims (12)

a transport mechanism for transporting the print medium;
an image forming unit that forms an image on the print medium;
an in-line sensor movable in a first scanning direction perpendicular to a transport direction of the print medium or in a second scanning direction opposite to the first scanning direction to scan one or more color patches formed on the print medium;
a control unit that controls the image forming unit to form the one or more color patches on the printing medium in accordance with a conveyance speed of the printing medium and a movement speed of the in-line sensor;
a trigger sensor that detects a trigger mark and outputs the detection result to the control unit ;
the one or more color patches include a first color patch that is scanned last before switching from the first scanning direction to the second scanning direction, and a second color patch that is scanned first after the switching,
the image forming unit forms a first trigger mark and a second trigger mark between the first color patch and the second color patch along the transport direction;
the trigger sensor detects that scanning in the first scanning direction has ended in response to detecting the first trigger mark;
The image forming apparatus, wherein the trigger sensor detects the start of scanning in the second scanning direction in response to detecting the second trigger mark . The image forming device of claim 1, wherein the color patches are arranged according to information on the print medium. The image forming device of claim 2, wherein the information includes paper type and size. The image forming apparatus of any one of claims 1 to 3, wherein the inline sensor includes a spectrophotometer. The image forming apparatus according to claim 4 , wherein the trigger sensor is included in the in-line sensor. The image forming apparatus according to claim 4 , wherein the trigger sensor is provided separately from the in-line sensor. The image forming apparatus of any one of claims 1 to 6, wherein the difference between the transport speed of the transport mechanism when forming the one or more color patches on the print medium and the transport speed when forming an image other than the one or more color patches on the print medium is within a predetermined range. 8. The image forming apparatus according to claim 1, wherein the image forming section further forms a third trigger mark at a predetermined position relative to the position of the one or more color patches. the placement of the third trigger mark is determined in accordance with the transport speed of the print medium and the movement speed of the in-line sensor;
The image forming apparatus according to claim 8 , wherein the trigger sensor waits in a measurement mode in response to detecting the third trigger mark . The image forming apparatus of any one of claims 1 to 9, wherein the control unit performs color adjustment based on a signal output from the inline sensor by scanning the one or more color patches. A control method for an image forming apparatus, comprising:
transporting a print medium;
forming an image on the print medium;
and moving an in-line sensor in a first scanning direction perpendicular to a transport direction of the print medium or in a second scanning direction opposite to the first scanning direction to scan one or more color patches formed on the print medium;
the step of forming the image includes a step of forming the one or more color patches on the print medium in accordance with a transport speed of the print medium and a movement speed of the in-line sensor;
the one or more color patches include a first color patch that is scanned last before switching from the first scanning direction to the second scanning direction, and a second color patch that is scanned first after the switching,
the step of forming the image further includes the step of forming a first trigger mark and a second trigger mark between the first color patch and the second color patch along the transport direction,
The control method includes a step of detecting that scanning in the first scanning direction has ended in response to a trigger sensor detecting the first trigger mark;
detecting, in response to the trigger sensor detecting the second trigger mark, that scanning in the second scanning direction is to be started . A program for controlling an image forming apparatus, the program including:
transporting a print medium;
forming an image on the print medium;
and moving an in-line sensor in a first scanning direction perpendicular to a transport direction of the print medium or in a second scanning direction opposite to the first scanning direction to scan one or more color patches formed on the print medium;
the step of forming the image includes a step of forming the one or more color patches on the print medium in accordance with a transport speed of the print medium and a movement speed of the in-line sensor;
the one or more color patches include a first color patch that is scanned last before switching from the first scanning direction to the second scanning direction, and a second color patch that is scanned first after the switching,
the step of forming the image further includes the step of forming a first trigger mark and a second trigger mark between the first color patch and the second color patch along the transport direction,
the program includes a step of detecting that scanning in the first scanning direction has ended in response to a trigger sensor detecting the first trigger mark;
detecting, in response to the trigger sensor detecting the second trigger mark, that scanning in the second scanning direction is to be started .