JP2021094785A - Portable image forming apparatus and image forming method - Google Patents

Abstract

To enhance visibility of an image formed on a colored image forming medium.SOLUTION: A portable image forming apparatus 100 forms an image while moving in one direction on an image forming medium. An image forming apparatus includes: an image forming unit 120 which is arranged in a direction intersecting with the one direction, and has at least one row of nozzle rows having a plurality of discharge nozzles for discharging ink; an imaging unit 160 which picks up an image of a surface of the image forming medium and generates image pickup data; an image analysis unit 111 for analyzing color of a surface of the image forming medium on the basis of the image pickup data and determining whether the surface of the image forming medium is colored or not; and a discharge amount adjusting unit 113 which adjusts a discharge amount of ink from the image forming unit so as to increase color difference between color of the surface of the image forming medium and color of an image reproduced by the image forming unit in the case where the surface of the image forming medium is determined to be colored.SELECTED DRAWING: Figure 1

Description

The present invention relates to a portable image forming apparatus.

In recent years, a portable image forming apparatus, a so-called handy printer, has been put into practical use. Since the handy printer prints on various printing media (printing objects), printing on a printing medium having irregularities, for example, is also assumed. To solve such a problem, for example, in Patent Document 1, an image is formed by adhering ink to a transfer portion, and the ink to which the transfer portion is attached is rotationally conveyed and adhered to a medium to attach the image to a printing medium. We are proposing a transfer technology.

Japanese Unexamined Patent Publication No. 2016-049724

The inventor of the present application has focused on the fact that the handy printer is expected to print on a colored printing medium. On the other hand, when the print medium is colored, how the printed image is visually recognized on the colored print medium has not been sufficiently examined.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for improving the visibility of an image formed on a colored image forming medium.

The present invention provides a portable image forming apparatus for forming an image while moving in one direction on an image forming medium. The image forming apparatus is arranged in a direction intersecting the one direction, and has an image forming portion having at least one row of nozzles having a plurality of ejection nozzles for ejecting ink, and the surface of the image forming medium. An imaging unit that captures images and generates imaging data, and an image analysis unit that analyzes the surface color of the image forming medium based on the imaging data and determines whether or not the surface of the image forming medium is colored. When it is determined that the surface of the image forming medium is colored, the image is such that the color difference between the surface color of the image forming medium and the color of the image reproduced by the image forming portion becomes large. It is provided with an ejection amount adjusting unit for adjusting the ejection amount of ink from the forming portion.

The present invention provides an image forming method for forming an image while moving a portable image forming apparatus in one direction on an image forming medium. In the image forming method, the image forming apparatus comprises an image forming portion having at least one row of nozzles arranged in a direction intersecting the one direction and having a plurality of ejection nozzles for ejecting ink. The image forming method includes an imaging step of imaging the surface of the image forming medium to generate imaging data, and analyzing the color of the surface of the image forming medium based on the imaging data to obtain the surface of the image forming medium. An image analysis step for determining whether or not the image is colored, and when it is determined that the surface of the image forming medium is colored, the color of the surface of the image forming medium and the image reproduced by the image forming unit It is provided with an ejection amount adjusting step of adjusting the ejection amount of ink from the image forming portion so that the color difference between the colors becomes large.

According to the present invention, the visibility of an image formed on a colored image forming medium is improved.
Providing technology

It is a block diagram which shows the functional structure of the portable image formation system 10 which concerns on one Embodiment of this invention. It is an internal perspective view which shows the mechanical structure of the image forming apparatus 100 which concerns on one Embodiment. It is a flowchart which shows the content of the image formation process which concerns on 1st Embodiment. It is explanatory drawing which shows the state of image formation on the white Western envelope E which concerns on 1st Embodiment. It is explanatory drawing which shows the state of image formation on the colored Western envelope Ea which concerns on 1st Embodiment. It is a flowchart which shows the content of the image formation process which concerns on 2nd Embodiment. It is explanatory drawing which shows the state of image formation on the colored Western envelope Ea which concerns on 2nd Embodiment.

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of a portable image forming system 10 according to an embodiment of the present invention. The portable image forming system 10 includes a portable image forming device 100 and a smartphone 200. The image forming apparatus 100 includes a control unit 110, an image forming unit 120, an operation display unit 130, a storage unit 140, a communication interface unit (also referred to as a communication I / F unit) 150, an imaging unit 160, and optics. It is equipped with a sensor 170.

The smartphone 200 includes a control unit 210, an operation display unit 230, a storage unit 240, a communication interface unit 250, and an image pickup unit 260. The smartphone 200 is connected to the image forming apparatus 100 by short-range wireless communication using the communication interface unit 250 and the communication interface unit 150. In the present embodiment, the short-range wireless communication uses CLASS1 of BLUETOOTH (registered trademark). BLUETOOTH (registered trademark) CLASS1 is a communication with an output of 100 mW, and is a short-range wireless communication capable of communicating within a distance of about 100 m between the image forming apparatus 100 and the smartphone 200.

The operation display unit 130 of the image forming apparatus 100 and the operation display unit 230 of the smartphone 200 function as a touch panel, display various menus as input screens, and accept customer operation inputs. In the portable image forming system 10, the user can generate imaging data with the smartphone 200 and print it with the image forming apparatus 100 based on the imaging data.

The control units 110 and 210 and the image forming unit 120 include main storage means such as RAM and ROM, and control means such as MPU (Micro Processing Unit) and CPU (Central Processing Unit). In addition, the control units 110 and 210 have controller functions related to interfaces such as various I / O, USB (universal serial bus), bus, and other hardware.

The control units 110 and 210 control the entire image forming apparatus 100 and the smartphone 200, respectively. The control unit 110 includes an image analysis unit 111, a light environment calibration unit 112, and a discharge amount adjusting unit 113. The functions of the image analysis unit 111, the optical environment calibration unit 112, and the discharge amount adjustment unit 113 will be described later.

The storage units 140 and 240 are storage devices including a hard disk drive, a flash memory, and the like, which are non-volatile recording media, and store control programs and data of processes executed by the control units 110 and 210, respectively.

FIG. 2 is an internal perspective view showing the mechanical structure of the image forming apparatus 100 according to the embodiment. An operation display unit 130 is arranged on the upper surface of the image forming apparatus 100 (see FIG. 2A). An imaging unit 160 having a field of view FOV is arranged on the side surface of the image forming apparatus 100. An image forming unit 120 and an optical sensor 170 are arranged on the lower surface of the image forming apparatus 100. Four rollers (not shown) are further arranged on the lower surface of the image forming apparatus 100 so that the image forming apparatus 100 can easily move linearly in the sub-scanning direction.

The image forming unit 120 includes a print head 120H having a single nozzle array having a plurality of ejection nozzles arranged in a main scanning direction which is a direction intersecting the sub scanning directions (for example, a vertical direction). The print head 120H discharges K ink to realize monochrome printing. The optical sensor 170 can measure the relative movement amount of the image forming apparatus 100 with respect to the print target by using the same principle as that of the optical mouse. The image forming unit 120 ejects ink according to the relative movement amount of the image forming apparatus 100 with respect to the print target measured by the optical mouse in the sub-scanning direction.

The image forming unit 120 ejects ink from the print head 120H based on an ink gradation value representing an image density to be reproduced. In this example, the image forming unit 120 can reproduce three gradations per ink dot by using ink droplets (large dots and small dots) of two sizes, large and small. In this example, the image forming apparatus 100 has two modes, for example, an ink save mode for suppressing consumption of ink in advance and a high-density high-quality image mode.

As a result, the image forming unit 120 can form a plurality of columns of text TE (see FIG. 2B) and other images with respect to the print target. The multi-column text TE has a predetermined positional relationship (with a predetermined vertical interval at a parallel angle) with respect to the text T1 on the first line (character string: 1-2-3 Kasumigaseki, Chiyoda-ku, Tokyo). It is assumed that the address in which the layout in which the text T2 (character string: ABC Co., Ltd.) of the second line is formed is specified. The image representing the text T1 on the first line is also called the first image. The image representing the text T2 on the second line is also called the second image.

FIG. 3 is a flowchart showing the contents of the image forming process according to the first embodiment. FIG. 4 is an explanatory diagram showing a state of image formation on the white Western envelope E according to the first embodiment. FIG. 4A is an explanatory diagram showing a state before the start of image formation on the white Western envelope E. In this image forming process, the user uses the image forming apparatus 100 to print the address on the white western envelope E, which is a monochrome white western envelope. The white western envelope E is a horizontally long white envelope.

In step S100, the image forming apparatus 100 executes the imaging process. The image pickup process is automatically executed by arranging the image forming apparatus 100 on the surface of the Western envelope E, which is the object to be printed, with the switch on. The imaging unit 160 automatically executes an imaging process when, for example, an imaging target exists at a predetermined distance at the center position of the field of view FOV. Whether or not the imaging target exists at a predetermined distance can be determined, for example, by whether or not the contrast AF can focus within the adjustment range within the predetermined range.

The imaging unit 160 generates RGB image data as imaging data after focusing by contrast AF. The RGB image data is RGB image data representing an image in the field of view FOV on the Western envelope E with each RGB gradation value (0 to 255). However, in the imaging unit 160, the automatic exposure adjustment function is turned off or suppressed. Since it is assumed that the entire field of view FOV is within the range of the surface of the Western envelope E, when the exposure is automatically adjusted with reference to the field of view FOV, the density (brightness decrease) of the Western envelope E is measured. This is because it is expected to have an adverse effect on.

In step S200, the image analysis unit 111 executes the luminance calculation process. In the luminance calculation process, the image analysis unit 111 uses, for example, a calculation formula of the luminance value L (luminance value L≈0.3R + 0.6G + 0.1B), and uses each RGB gradation value of the image data ID to obtain the luminance value. Calculate L.

In step S300, the image analysis unit 111 compares the brightness L with the preset threshold value Th1. The image analysis unit 111 advances the process to step S400 when the brightness L is smaller than the threshold value Th1, and advances the process to step S800 when the brightness L is equal to or greater than the threshold value Th1. As described above, the image analysis unit 111 is configured to consider that the print medium (Western envelope E in this example) is not colored but white when the brightness L is the threshold value Th1 or more. There is.

In step S400, the image analysis unit 111 executes the saturation calculation process. In the saturation calculation process, the image analysis unit 111 calculates the saturation S by using, for example, the calculation formula of the saturation S (saturation S = (Imax-Imin) / Imax). Here, Imax is the maximum value among the RGB gradation values, and Imin is the minimum value among the RGB gradation values.

In step S500, the image analysis unit 111 compares the saturation S with the preset threshold Th2. The image analysis unit 111 advances the process to step S700 when the saturation S is larger than the threshold value Th2, and proceeds to the process to step S600 when the saturation S is equal to or less than the threshold value Th2. In this example, the image analysis unit 111 is configured to consider that the print medium (in this example, the Western envelope E) is colored when the saturation S is larger than the threshold Th2. On the other hand, when the saturation S is the threshold value Th2 or less, the image analysis unit 111 is configured to estimate the possibility that the amount of light in the shooting environment is small, that is, the environment is dark.

In step S600, the optical environment calibration unit 112 executes a blank paper calibration process. In the blank paper calibration process, the optical environment calibration unit 112 first asks, "Place the handy printer on the blank paper at the current location and touch the" Start calibration "icon. The message "" and the "calibration start" icon are displayed on the operation display unit 130. The user places the image forming apparatus 100 on a blank sheet of paper and touches the "calibration start" icon displayed on the operation display unit 130. At this time, the optical environment calibration unit 112 may perform the exposure adjustment of the imaging unit 160 and fix it at the exposure setting.

The optical environment calibration unit 112 calculates the brightness value L, assumes that the image in the field of view FOV is the surface of a blank sheet, adjusts the threshold value Th1, and sets the threshold value Th1a. Further, the optical environment calibration unit 112 sets a calibrated flag. As a result, the image analysis unit 111 can execute the processes of steps S100 to S400 again by using the threshold value Th1a assuming the light environment state in which the image forming apparatus 100 is placed and the exposure setting.

As a result, after the calibration process (step S600), in step S300, the image analysis unit 111 takes an image using the exposure setting set when the blank paper is imaged, and the Western envelope E in an environment close to that when the blank paper is imaged. It is possible to generate RGB image data that reproduces the surface color of. In this way, the image forming apparatus 100 can appropriately measure the color density of the surface of the Western envelope E even in a dark environment, for example.

As a result, if it is determined that the Western envelope E is not colored (step S300), the process proceeds to step S800. On the other hand, in the case of the colored Western envelope Ea (described later), it is determined that there is a possibility of coloring, and the process proceeds to step S400 to execute the saturation calculation process.

After the calibration process (step S600), in step S500, the image analysis unit 111 compares the saturation S with the threshold Th2. When the saturation S is larger than the threshold value Th2, the image analysis unit 111 advances the process to step S700. On the other hand, when the saturation S is the threshold value Th2 or less, the image analysis unit 111 confirms a flag indicating whether or not the calibration process (step S600) is being performed. Specifically, it is assumed that a flag is set when the print medium is colored gray.

When the flag is set, the image analysis unit 111 gives a message "The print target seems to be colored gray, so can I print with a darker color?" And "OK". The icon and the "NG" icon are displayed on the operation display unit 130. The image analysis unit 111 advances the process to step S700 in response to the touch of the “OK” icon, and proceeds to the process in step S800 in response to the touch of the “NG” icon.

In step S700, the discharge amount adjusting unit 113 executes the image density adjusting process. In the image density adjustment process, the ejection amount adjusting unit 113 increases the ink ejection amount. The reason for increasing the amount of ink ejected is to ensure the visibility of characters and the like when they are printed on a colored print medium. In this example, the image forming apparatus 100 has, for example, two modes, an ink save mode and a high-density high-quality image mode for suppressing the consumption of the ink amount in advance, and automatically switches to the high-density high-quality image mode.

FIG. 4B is an explanatory view showing a state during image formation on the white Western envelope E. In this example, since the white envelope E is not a colored printing medium, the character string T1 is printed with a normal ink ejection amount in the ink save mode.

FIG. 5 is an explanatory diagram showing a state of image formation on the colored Western envelope Ea according to the first embodiment. FIG. 5A is an explanatory diagram showing a state before the start of image formation on the colored Western envelope Ea. FIG. 5B is an explanatory diagram showing a state during image formation on the colored Western envelope Ea. In this example, since the colored Western envelope Ea is a colored printing medium, the character string T1a is printed with the ink ejection amount in the high image quality mode. As a result, the visibility of characters and the like printed on the colored Western envelope Ea, which is a colored printing medium, can be ensured.

As described above, the image forming apparatus 100 according to the first embodiment automatically analyzes the color of the print medium, and can ensure the visibility of the characters and the like to be printed even when the print medium is colored. In this example, the image forming apparatus 100 automatically switches to the high density high image quality mode, but is not limited to such a method. The image density adjustment process may be a process of relaxing the amount of large dots used, which is limited due to the ink duty limitation, and increasing the ratio of large dots used.

The ink ejection amount, also simply called the ink amount, is determined based on the ink gradation value under the ink duty limit. The ink duty limit is a limit on the amount of ink that can be ejected over a fixed area. The ink duty limit is typically determined based on the surface properties of the print medium (also referred to as the image forming medium). However, since the image forming apparatus 100 as a handy printer is premised on not choosing a print medium, it is set on a relatively safe side (a side with a small amount of ink).

FIG. 6 is a flowchart showing the contents of the image forming process according to the second embodiment. The image forming process according to the second embodiment is different from the image forming process according to the first embodiment in that step S650 is added. In step S650, the optical sensor 170 measures the relative movement amount of the image forming apparatus 100 with respect to the print medium using the same principle as that of the optical mouse, and measures the movement speed by differentiating the value. The optical sensor 170 is also called a moving speed measuring unit.

In step S650, the discharge amount adjusting unit 113 determines whether or not the image density adjusting process is executed according to the moving speed of the image forming apparatus 100 operated by the user, that is, the scanning speed in the sub-scanning direction. Specifically, the discharge amount adjusting unit 113 executes the image density adjustment process (step S700) when the moving speed is larger than the preset threshold value Th3, and the image density when the moving speed is equal to or less than the threshold value Th3. The adjustment process (step S700) is skipped.

FIG. 7 is an explanatory diagram showing a state of image formation on the colored Western envelope Ea according to the second embodiment. FIG. 7A is an explanatory diagram showing a state in which an image is being formed on the colored Western envelope Ea at a high speed (a speed faster than the threshold value Th3). FIG. 7B is an explanatory diagram showing a state in which an image is being formed on the colored Western envelope Ea at a low speed (a slow speed of a threshold value Th3 or less).

The inventor of the present application has focused on the fact that when a user prints at high speed, an image is often formed for the purpose of transmitting information such as an address, and visibility is usually emphasized. .. On the other hand, when the user prints at a low speed, he focused on the fact that he often desires to reproduce the color intended by the user for the purpose of reproducing an emotional image such as a pattern.

As described above, the image forming apparatus 100 according to the second embodiment estimates the purpose of the image forming of the user according to the moving speed of the image forming apparatus 100 as a user operation, and is appropriate according to the intention of the user. Image formation can be realized. The image forming apparatus 100 is not limited to the case where the adjustment of the ink ejection amount is completely prohibited when the moving speed is the threshold value Th3 or less, and the adjustment amount may be reduced, and the adjustment of the ink ejection amount is restricted ( Or it may be suppressed).

The present invention can be implemented not only in the above embodiments but also in the following modifications.

Modification 1: In the above embodiment, the image forming apparatus 100 includes a print head 120H having a single nozzle row, but has a plurality of nozzle rows for ejecting a plurality of types of ink having different hues from each other. However, the present invention can also be applied to an image forming apparatus capable of color printing. The present invention can be applied to an image forming apparatus having at least one row of nozzles.

Modification 2: In the above embodiment, when the print medium is colored, the visibility of characters and the like to be printed is ensured by increasing the amount of ink ejected, but the assurance of visibility according to the present invention is the ink. It is not limited to the method of increasing the discharge amount of the ink. Specifically, the present invention may adjust the ink ejection amount so that the difference in hue angle, which is the difference between the hue of the color of the printing medium and the hue of the reproduced image, becomes large, for example, in color printing. .. The present invention may be a method of changing the amount of ink ejected so that the color difference from the color of the print medium is generally large. The color difference can be calculated based on various criteria such as RGB Euclidean distance and LAB Delta E.

Modification 3: In the above embodiment, an image is taken in a state where the automatic exposure adjustment function of the image pickup unit is turned off or suppressed, and whether or not the print medium is colored is determined based on the brightness. However, the method is not limited to this method, and the determination may be made based on the operating amount of the automatic exposure adjustment function. Specifically, for example, a blank sheet of paper may be imaged, and the determination may be made based on the exposure adjustment amount at the time of imaging of the print medium under the same light environment. That is, the present invention prints when the difference between the adjustment amount of the automatic exposure adjustment at the time of imaging the surface color of the print medium and the adjustment amount of the automatic exposure adjustment at the time of imaging a blank sheet is equal to or more than a preset threshold value. It may be determined that the surface of the medium is colored.

Modification 4: In the above embodiment, it is assumed that the color of the surface of the print medium is uniform, but the present invention can cope with the case where the color of the surface of the print medium is not uniform. That is, since the image forming apparatus can measure the amount of movement in the main scanning direction, the color change is detected based on the imaging data, the position (color change position) is specified, and the ink is charged at the color change position. It can be configured so that the adjustment of the discharge amount can be switched. In the present invention, it is preferable to perform information transmission processing for notifying the user of a color change such as blinking of the operation display unit of the image forming apparatus, notification by a buzzer, and display of a warning to a smartphone in order to call the user's attention. ..

10 Image forming system 100 Image forming device 110, 210 Control unit 120 Image forming unit 130, 230 Operation display unit 140, 240 Storage unit 150, 250 Communication interface unit 160 Imaging unit 170 Optical sensor 200 Smartphone

Claims (8)

A portable image forming apparatus for forming an image while moving in one direction on an image forming medium.
An image forming unit having at least one row of nozzles arranged in a direction intersecting the one direction and having a plurality of ejection nozzles for ejecting ink.
An imaging unit that images the surface of the image forming medium and generates imaging data,
An image analysis unit that analyzes the color of the surface of the image forming medium based on the imaging data and determines whether or not the surface of the image forming medium is colored.
When it is determined that the surface of the image forming medium is colored, the image forming is performed so that the color difference between the surface color of the image forming medium and the color of the image reproduced by the image forming portion becomes large. An ejection amount adjustment unit that adjusts the amount of ink ejected from the unit,
An image forming apparatus comprising. The image forming apparatus according to claim 1.
The ejection amount adjusting unit is an image forming apparatus that increases the ejection amount of ink when it is determined that the surface of the image forming medium is colored. The image forming apparatus according to claim 1 or 2, further
A moving speed measuring unit for measuring a moving speed, which is the moving speed of the image forming apparatus in one direction, is provided.
The discharge amount adjusting unit executes the adjustment when the moving speed is larger than the preset threshold value, and limits the execution of the adjustment when the moving speed is equal to or less than the preset threshold value. Image forming device. The image forming apparatus according to any one of claims 1 to 3.
The image forming unit has a plurality of nozzle rows for ejecting a plurality of types of ink having different hues from each other.
When the ejection amount adjusting unit determines that the surface of the image forming medium is colored, the ejection amount adjusting unit adjusts the ejection amount of the plurality of types of inks according to the hue of the color of the image forming medium and the image forming unit. An image forming device that adjusts the amount of ink ejected so that the difference in hue angle, which is the difference in hue of the reproduced image, becomes large. The image forming apparatus according to any one of claims 1 to 4.
The image analysis unit is an image forming apparatus that determines that the surface of the image forming medium is colored when the color saturation of the surface of the image forming medium is equal to or higher than a preset threshold value. The image forming apparatus according to any one of claims 1 to 5.
When the difference between the adjustment amount of the automatic exposure adjustment at the time of imaging the surface color of the image forming medium and the adjustment amount of the automatic exposure adjustment at the time of imaging a blank sheet of the image forming medium is equal to or more than a preset threshold value. , An image forming apparatus for determining that the surface of the image forming medium is colored. The image forming apparatus according to any one of claims 1 to 6.
The image analysis unit is an image forming apparatus that detects a change in the surface of the image forming medium and performs information transmission processing for notifying the user of the change in color in response to the detection. An image forming method for forming an image while moving a portable image forming apparatus in one direction on an image forming medium.
The image forming apparatus includes an image forming unit which is arranged in a direction intersecting the one direction and has at least one row of nozzles having a plurality of ejection nozzles for ejecting ink.
The image forming method is
An imaging step of imaging the surface of the image forming medium to generate imaging data,
An image analysis step of analyzing the color of the surface of the image forming medium based on the imaging data and determining whether or not the surface of the image forming medium is colored.
When it is determined that the surface of the image forming medium is colored, the image forming is performed so that the color difference between the surface color of the image forming medium and the color of the image reproduced by the image forming portion becomes large. The ejection amount adjustment process that adjusts the ejection amount of ink from the part, and
An image forming method comprising.

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