JP2023179232A - Printing device, printing method, and program - Google Patents

Abstract

To provide a printing technique that enables a printing medium having a plurality of different color development layers laminated thereon to properly develop colors using a plurality of heater elements.SOLUTION: A printing device 40 is provided with a plurality of heater elements 34 that apply heating energy to a printing medium 10 in which a plurality of color development layers 14, 16 and 18, which are applied with different heating energy to develop colors different from each other, are laminated. Further the printing device 40 is provided with obtaining means 46 that obtains respective heating characteristics of the plurality of heater elements, and generating means 401 that generates printing data for making the plurality of heater elements 34 generate heating energy on the basis of image data corresponding to pixels, on the basis of respective color developing/heating characteristics and heating characteristics of the plurality of color development layers. Driving control means 405 makes the plurality of heater elements 34 respectively generate heating energy on the basis of printing data generated by the generating means 401.SELECTED DRAWING: Figure 11

Description

The present disclosure relates to a printing technique in which a heating element heats a printing medium in which a plurality of coloring layers that produce different colors are stacked to form an image.

Conventional technology

2. Description of the Related Art Thermal printing, which performs color printing using printing media such as thermal paper and ink ribbon, is conventionally known. Regarding such thermal printing, Patent Document 1 describes that printing is performed by correcting the energy applied to the heating elements based on thermal and mechanical variations in a plurality of heating elements arranged in one line in a thermal transfer printing device. A technique for reducing density unevenness in images has been disclosed.

JP2016-68360A

However, in Patent Document 1, regardless of the color of the ink area to be heated, the applied energy applied to each heating element is corrected according to variations in the heating elements. For this reason, even if the heat generation amount of the heating element is corrected using the correction technique disclosed in Patent Document 1 for a printing medium in which a plurality of coloring layers with different coloring heating characteristics are laminated, each coloring layer cannot be properly colored. .

The present disclosure aims to provide a printing technique that allows a printing medium in which a plurality of different coloring layers are laminated to be appropriately colored using a plurality of heating elements.

The present disclosure provides a printing device including a plurality of heating elements that apply heating energy to a printing medium in which a plurality of coloring layers that generate different colors when different heating energies are applied to a printing medium, The method further comprises a generation means for generating print data for causing the heat generation element to generate the heating energy based on image data corresponding to a pixel, and an acquisition means for acquiring heat generation characteristics of each of the plurality of heat generation elements. The generating means is characterized in that the generating means generates the print data corresponding to the image data based on the coloring heating characteristics and the heat generation characteristics of the coloring layer.

According to the present disclosure, it is possible to properly color a print medium in which a plurality of different coloring layers are laminated using a plurality of heating elements.

FIG. 2 is a diagram showing the structure of a print medium used in this embodiment. FIG. 3 is a diagram for explaining color development conditions of a first print medium. (a) and (b) are diagrams for explaining a print head. FIG. 1 is an internal configuration diagram of a printing device in a first embodiment. FIG. 2 is a block diagram for explaining the configuration of control in the printing system. 3 is a flowchart for explaining print service providing processing. It is a figure showing an example of a heating pulse in a 1st embodiment. 7 is a flowchart showing a process for creating density unevenness correction values. FIG. 3 is a partially enlarged view showing an example of a detected image in the first embodiment. It is a figure which shows the heating pulse before correction|amendment and after correction|amendment in 1st Embodiment. 7 is a flowchart showing image forming processing in the first embodiment. 7 is a flowchart showing image forming processing in a second embodiment.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure according to the claims, and not all combinations of features described in the present embodiments are essential to the solution of the present disclosure. .

(First embodiment)
<Print media>
FIG. 1 is a diagram showing the structure of a print medium used in this embodiment. The print medium 10 has a third image forming layer 18 , a second spacer layer 17 , a second image forming layer 16 , a first spacer layer 15 , a first image forming layer 14 , and a protective layer 13 on a base material 12 . It is constructed by sequentially laminating layers. The side of the protective layer 13 (the upper side in FIG. 1) is the front surface, and is the side with which a print head (described later) comes into contact and the formed image is observed.

The base material 12 is a white layer that reflects light, and the protective layer 13 is a transparent layer. The first image forming layer (first coloring layer) 14, the second image forming layer (second coloring layer) 16, and the third image forming layer (third coloring layer) 18 are basically colorless and transparent. , each activated at a specific temperature and produces a different color (yellow, magenta, cyan).

The first spacer layer 15 and the second spacer layer 17 are layers for controlling the diffusion of heat applied to the protective layer 13, and the thickness of each is determined by the rate of heat diffusion and the thickness of the three image forming layers. It is adjusted according to the activation temperature, etc.

The time it takes for the temperature applied to the surface to reach the underlying image forming layer depends on the thickness of the spacer layer, and the applied heat is radiated as it diffuses. For this reason, for example, by applying heat higher than the activation temperature of the upper and lower image forming layers to the surface of the print medium for a short period of time, only the upper image forming layer is activated and the lower image forming layer is activated. You can prevent this from happening. In addition, by applying a temperature higher than the activation temperature of the lower image forming layer and lower than the activation temperature of the upper image forming layer for a long time, the lower image forming layer can be activated without activating the upper image forming layer. The imaging layer of the image forming layer can be activated. That is, by adjusting parameters such as the temperature of heat applied to the surface of the protective layer 13 (heating temperature) and application time according to image data, the first image forming layer 14, the second image forming layer 16, and the third image forming layer Image forming layers 18 can be individually activated to adjust color development.

In the print medium after the image has been formed in this way, the light incident from the protective layer 13 passes through the spacer layer and the unactivated image forming layer, and passes through the activated image forming layer or the base material 12. reflect. Therefore, when the print medium 10 is visually observed from the front side, the observer can visually recognize the colors corresponding to the combination of light reflected by the individual image forming layers and recognize it as an image.

The colors (coloring materials) developed in the three image forming layers are not particularly limited. In the following, a case will be described in which a print medium in which the first image forming layer 14 contains yellow, the second image forming layer 16 contains magenta, and the third image forming layer 18 contains cyan coloring materials is used as the first printing medium. Although described, the configuration of the print medium applicable to the present disclosure is not limited thereto.

Generally, in a print medium used to form a full-color image, the first image forming layer 14, the second image forming layer 16, and the third image forming layer 18 contain yellow, magenta, and cyan, as described above. Each of them is colored. However, the color order (layering order) of each image forming layer in the printing medium 10 applicable to the present disclosure and the combination of colors to be developed are not limited to the example shown in FIG. 1. Furthermore, in the example shown in FIG. 1, image forming layers (coloring layers) corresponding to three colors are provided, but an image forming layer corresponding to more colors or an image forming layer corresponding to fewer colors is provided. may be provided. In FIG. 1, each image forming layer has the same thickness, but image forming layers having different thicknesses may be provided depending on the color (coloring material).

Further, the thickness of the spacer layers 15 and 17 provided between the image forming layers 14, 16, and 18 is determined by the coloring heating characteristics of the image forming layers 14, 16, and 18, and the thickness of the spacer layers 15, 17 provided between the image forming layers 14, 16, and 18. It can be set as appropriate depending on the heat conduction characteristics, thermal diffusivity, etc. Each spacer layer may be formed of the same material or may be formed of different materials. Since the spacer layer functions to control heat diffusion within the print medium 10, when the first spacer layer 15 and the second spacer layer 17 are made of the same material, the second spacer layer 17 is Preferably, the thickness is four times or more.

Furthermore, although the three image forming layers (first to third image forming layers) 14, 16, and 18 in the printing medium 10 shown in FIG. The formation layer may be arranged on the opposite side of the base material 12.

Note that heating the print medium 10 is preferably performed using a print head that applies heat to the print medium, but other methods may be used. It is also possible to use printheads with other known heating means, for example modulated light sources (such as laser-like means).

<Color heating characteristics>
FIG. 2 is a diagram for explaining the color development conditions of the first print medium. In the figure, the horizontal axis represents the time to heat the surface of the print medium 10 (heating time), and the vertical axis represents the heating temperature (heating temperature). Then, a first image forming layer 14 containing a yellow (Y) coloring material, a second image forming layer 16 containing a magenta (M) coloring material, and a third image forming layer 18 containing a cyan (C) coloring material are formed. Combinations of heating time and heating temperature for activation are shown as region 21, region 22, and region 23.

As shown in FIG. 2, the yellow layer, which is the first image forming layer 14, develops color when a temperature of Ta3 or higher is applied for t1 or more. The magenta layer, which is the second image forming layer 16, develops color when a temperature of Ta2 (<Ta3) or higher is applied to the layer t2 (>t1) or higher. The cyan layer, which is the third image forming layer 18, develops color when a temperature of Ta1 (<Ta2<Ta3) or higher is applied to t3 (>t2>t1) or higher.

For example, for an area where only yellow color is desired to be developed, a temperature of Ta3 or higher may be applied for a period of t1 or more and t2 or less. For a region where only magenta is desired to be colored, a temperature of Ta2 or more and Ta3 or less may be applied for a period of t2 or more and t3 or less. For a region where it is desired to develop only cyan color, a temperature of Ta1 or more and Ta2 or less may be applied for t3 or more. In this way, by individually controlling the color development of each color element, it is possible to express a color space using a combination of yellow, magenta, and cyan.

Ta1, Ta2, and Ta3 are values that are adjusted depending on the materials contained in each image forming layer, but generally they are set at appropriate intervals (temperature difference) within the range of about 90°C to about 300°C. It is preferable that this is set. For example, Ta1 is required to be set at a temperature as low as possible without being activated during shipping and storage, and is preferably about 100°C. On the other hand, for Ta3, the temperature is required to be such that the second and third image forming layers 15 and 18 located below are not activated by short-term thermal diffusion, and is preferably about 200°C. Regarding Ta2, it is required that the temperature does not reach Ta1 or Ta3 even if a slight temperature change occurs, and is preferably about 140°C to 180°C.

Note that even when each image forming layer is applied with heating energy within a corresponding region, the color density formed differs depending on the position within the region. For example, when heating energy in the area 22 is applied to the second image forming layer 16, even if the heating time is the same, applying a temperature close to Ta3 has a higher density than applying a temperature close to Ta2. images will be formed.

<Print head>
FIGS. 3A and 3B are diagrams for explaining the print head 30 used in this embodiment. 3(a) is a side view showing a state in which printing is being performed on the print medium 10, and FIG. 3(b) is a plan view showing the surface of the print head 30 that is brought into contact with the print medium 10.

As shown in FIG. 3A, a glaze 32 and a convex glaze 33 made of the same material as the glaze 32 are provided on one surface of the base 31 of the print head 30. A heating element 34 is disposed at the most protruding portion of the convex glaze 33. Note that it is preferable that a protective film (not shown) for protecting the glaze 32, the convex glaze 33, and the heating element 34 be provided so as to cover the surfaces thereof. Note that the convex glaze 33 is not an essential component, and the heating element 34 may be arranged on the glaze 32 made of a flat plate. A heat sink 35 is provided on the other side of the base 31 so that the entire print head is cooled by the use of a fan.

The x direction shown in FIG. 3 corresponds to the width direction of the print medium 10, and the print medium 10 crosses the x direction at a predetermined speed (orthogonal in this example) while contacting the convex glaze 33 and the heating element 34 of the print head 30. ) is transported in the y direction.

In the print head 30, the glaze 32 and the convex glaze 33 extend in the x direction by a distance that covers the width of the print medium 10, as shown in FIG. 34 are arranged substantially linearly along the x direction (first direction). In this embodiment, the length of each heating element 34 in the x direction is set to about 40 μm, and the length in the y direction is set to about 120 μm. When the print medium 10 is conveyed as shown in FIG. 3(b), the print medium 10 comes into contact with the convex glaze 33 including the heating element 34 over a length of about 200 microns or more.

Each heating element arranged in the print head generates heat when supplied with electric current, and the heat is applied to the print medium 10. The print medium is conveyed while receiving heat from the resistance of the print head 30, and each image forming layer develops color due to the applied heat. As a result, an image is formed line by line along the direction in which the heating elements 34 are arranged. Note that although this embodiment employs an infrared imaging method in which the heating element 34 as a heat source irradiates infrared rays onto the recording medium to heat the print medium, other methods or heat sources may also be used. good.

The time that heat is applied to print media 10 by print head 30 typically ranges from about 0.001 milliseconds to about 100 milliseconds for each line of the image. The upper limit of the heat application time is set by the printing speed, while the lower limit of the heat application time is determined by constraints of an electronic circuit (not shown).

One pixel area on the print medium 10 is determined by the size of the heating element 34 in the x direction, and determined by the size of the heating element 34 and the conveyance speed of the print medium 10 in the y direction. Therefore, the size of one pixel area is not particularly limited, but is generally 100 to 600 dpi (dots/inch) in the x and y directions. The sizes of the regions in the x direction and the y direction of one pixel region may be different. In this embodiment, the area is approximately 40 μm in both the x direction and the y direction. That is, in the print medium 10, individual pixels are arranged at a density of about 600 dpi (dots/inch).

<Printing device>
FIG. 4 is an internal configuration diagram of the printing apparatus according to this embodiment. In the figure, the x direction indicates the width direction of the print medium 10, the y direction indicates the conveyance direction of the print medium 10, and the z direction indicates the vertical direction. The printing device 40 is provided with a print head 30, a holding section 41, a conveyance roller 42, a platen 43, a discharge port 44, a temperature sensor 45, a camera (obtaining means) 46, an imaging button 47, a battery 48, and the like. The print medium 10 before printing is stored in the holding section 41. At this time, the plurality of print media 10 are stacked on top of each other with their surfaces (protective layer 13 side in FIG. 1) facing upward (+z direction).

When a print job is received, a conveying roller 42 serving as a conveying means rotates and conveys the print medium 10 located at the lowest layer in the y direction. Thereby, the print medium 10 is sent to the printing section where the print head 30 and platen 43 are arranged. In the printing section, the convex glaze 33 of the print head 30 contacts the surface (upper surface) of the print medium 10 being conveyed, and the platen 43 supports the print medium 10 during printing from the bottom surface. The heating element 34 is driven according to print data, and the print medium 10 develops color in accordance with the heat applied by the heating element 34. The print medium 10 after being printed by the print head 30 is discharged from the discharge port 44 .

A temperature sensor 45 is provided around the nip between the print head 30 and the platen 43 to detect the temperature supplied by the print head 30. Note that the object detected by the temperature sensor 45 may be, for example, the temperature of the heating element 34 as a heat source included in the print head 30, or the surface temperature of the print medium 10. Moreover, a plurality of temperature sensors 45 are arranged along the width direction of the print head 30 by arranging a plurality of them, so that the temperature sensor 45 is configured to be able to measure the entire width direction of the recording medium 10 . The conveyance speed of the print medium 10 is controlled according to the speed of image formation, the resolution at the time of image formation, and the like. For example, when forming a high-resolution image, the conveyance speed is controlled to be slower than when forming a low-resolution image. Further, when priority is given to printing speed, control is performed to increase the conveyance speed and lower the resolution.

<System configuration>
FIG. 5 is a diagram showing an example of the overall configuration of the system in this embodiment. As shown in FIG. 5, the system according to this embodiment includes the printing device 40 shown in FIG. 4 and a smartphone 50 as a host device for the printing device 40. In addition to the smartphone 50, the host device can be a personal computer, a tablet terminal, or a digital camera.

The smartphone 50 includes a CPU (Central Processing Unit) 501, a RAM (Read Only Memory) 502, and an HDD (Hard Disk Drive) 503. Furthermore, the smartphone 50 includes a communication I/F 504, an input I/F 505, a display device I/F 506, a camera 507, and the like. These components are communicatively connected to each other by an internal bus.

The CPU 501 executes processing according to programs and various data held in the HDD 503 and RAM 502. The RAM 502 is volatile storage and temporarily holds programs and data. Further, the HDD 503 is a nonvolatile storage and holds programs and data. The camera 507 is a device that can capture images by user operation, and captured image data is held in the HDD 503.

The communication I/F 504 is an interface that controls communication with external devices, and here controls the transmission and reception of data with the printing device 40. As a connection method for transmitting and receiving data here, a wired connection such as USB or a wireless connection such as Bluetooth (registered trademark) or WiFi (registered trademark) can be used. The input device I/F 505 is an interface that controls an HID (Human Interface Device) such as a touch panel, and accepts input from a user. The display device I/F 506 controls display on a display device (not shown) that displays captured images, image data, and the like.

The printing device 40 includes a CPU 401, a RAM 402, a ROM 403, a communication I/F 404, a head controller 405, a camera controller 406, an image processing accelerator 407, and the like. Further, these components are communicatively connected to each other by an internal bus. The CPU 401 transfers programs and various data held in the ROM 403 and RAM 402 to a predetermined memory area of the RAM 402, and executes processes of each embodiment described later in accordance with the programs and data. The RAM 402 is a volatile storage and temporarily holds programs and data transferred by the CPU 401 and the like as described above. Further, the ROM 403 is a non-volatile storage, and holds table data and programs used in processing to be described later.

The communication I/F 404 is an interface that controls communication with an external device, and here controls the transmission and reception of data with the smartphone 50. The head controller 405 operates as a drive control unit that performs a heating operation on the print head 30 shown in FIG. 3 based on print data. That is, the head controller 405 reads control parameters and print data from a predetermined address in the RAM 402. Then, when the CPU 401 writes the control parameters and print data to a predetermined address in the RAM 402, processing by the head controller 405 is started, and the heating operation of the print head 30 is performed.

Camera controller 406 controls the operation of camera 46 shown in FIG. Specifically, when the user presses the imaging button 47, the camera controller 406 issues an imaging instruction to the camera 46, and the camera 46 that has received the imaging instruction performs imaging. The captured image is temporarily held in RAM 402.

When printing a captured image, etc., the head controller 405 starts processing and controls the heating operation of the print head 30 to the print medium. The image processing accelerator 407 is configured by hardware and can perform predetermined image processing at high speed.

When performing image processing, the CPU 401 first writes parameters and data necessary for image processing to a predetermined address in the RAM 402. In response to this, the image processing accelerator 407 is activated and starts predetermined image processing. Note that in the present disclosure, the image processing accelerator 407 is not necessarily a necessary element. It is also possible for the CPU 401 to execute table parameter creation processing and image processing, which will be described later, depending on the specifications of the printing apparatus 40 and the like.

Further, the temperature sensor 45 detects the ambient temperature of the heat generating element 34 of the print head 30, and provides the detection result to the CPU 401 and the like as temperature information. The CPU 401 performs various processes for controlling heat generation of each heat generating element 34 of the print head 30 based on predetermined acquired information including temperature information and the like. Details of the processing and control executed by the CPU 401 will be described later.

Note that in this embodiment, a system configuration in which two independent devices, that is, a printing device 40 and a smartphone 50 are communicably connected, is illustrated, but it is also possible to realize this system configuration within a single device configuration. It is. Further, it is also possible to implement the above system configuration in a device in which the printing device 40 and the imaging device (not shown) are integrated.

<Printing service>
FIG. 6 is a flowchart showing the flow of a series of processes in the print service providing process, and in the figure, dashed arrows indicate data transmission and reception. In FIG. 6, the processes in S601 to S605 are executed in the smartphone 50, and the processes in S611 to S616 are executed in the printing device 40. These processes are performed by a CPU provided in each device. That is, in the smartphone 50 which is the host device, the CPU 501 reads and executes the programs held in the HDD 503 and the RAM 52, thereby performing the processes of S601 to S605. Furthermore, in the printing apparatus 40, the CPU 401 reads and executes programs held in the ROM 403 and RAM 402, thereby performing the processes of S611 to S616. Note that in the figure, broken line arrows indicate data transmission and reception.

When the printing device 40 is powered on, it first confirms in S611 that it is capable of printing, and when it is confirmed that it is in a printable state, it enters a standby state.

On the other hand, the smartphone 50 executes the print service Discovery in S601. Here, as the print service Discovery, a search process for peripheral devices according to a user's operation or a search process for periodically searching for a printing device that can provide a print service is performed. Note that the smartphone 50 may perform a process of making an inquiry when the smartphone 50 and the printing device 40 are connected.

In step S612, upon receiving the printing service Discovery from the smartphone 50, the printing apparatus 40 notifies the printing apparatus 40 that it is a device capable of providing printing services as a response thereto.

In step S<b>602 , when the smartphone 50 receives a notification from the printing device 40 that a printing service can be provided, the smartphone 50 requests printability information from the printing device 40 .

In step S613, the printing apparatus 40 notifies information about printing services that it can provide in response to the request for printable information from the smartphone 50.

Upon receiving the printable information from the printing device 40, the smartphone 50 generates a user interface for creating a print job based on the printable information in step S603. Specifically, information such as print image designation, print size, printable paper size, etc., and information indicating appropriate options are displayed on a display (not shown) based on the printability information of the printing device 40. . Then, settings made by the user via an input device (not shown) such as a touch panel are accepted. After that, in S604, the smartphone 50 issues a print job based on the setting information received from the user, and transmits it to the printing device 40.

In S614, the printing device 40 receives a print job from the smartphone 50. The printing device 40 then analyzes and executes the received print job (S615). Details of the process (print process) corresponding to the print job will be described later.

When the printing process is completed, the printing device 40 transmits print completion notification information to the smartphone 50 in S616. As a result, the processing on the printing device 40 side is completed and the printing device 40 enters a standby state.

Meanwhile, the smartphone 50 receives the print job completion notification information in S605, displays the notification information on the display, and transmits the notification information to the user. With the above, the processing on the smartphone 50 side is completed.

In the above description, a so-called PuLL type communication method is exemplified in which various types of information transmission are performed by making a request from the smartphone 50 side to the printing device 40, and the printing device 40 responds to the request. However, the communication method performed between the smartphone 50 and the printing device 40 is not limited to pull type communication. It is also possible to adopt a so-called push type communication method in which the printing device 40 spontaneously makes a call to one or more smartphones 50 existing in the network.

<Print head control>
The heating control of the print head 30 performed in this embodiment will be explained.

FIG. 7 is a diagram illustrating a heating signal that applies a voltage to one heating element 34 of the print head in order to color one pixel on the print medium 10. In Figure 7, heating signals are shown to color each pixel of yellow (Y), magenta (M), cyan (C), red (R), green (G), blue (B), and black (K). ing. Each heating signal is composed of a pulse signal train including a plurality of heating pulse signals (voltage pulses). Note that the horizontal axis in FIG. 7 represents time, and the vertical axis represents the voltage of the heating signal.

In FIG. 7, the heating signal forming one pixel has time corresponding to 52 sections (sections a to Z), and a predetermined number of heating pulse signals are included in the 52 sections. The pulse width (time) of one heating pulse signal is set within the time corresponding to one section. When the length of one section is Δt0, the time required to form one pixel is Δt0×52. In other words, time equivalent to 52 cycles of heating pulses is used to develop color for one pixel, and color development is controlled by a pulse signal train consisting of a plurality of heating pulse signals included within this time.

The heating pulse signal changes to a binary voltage of High and Low (ON and OFF). In the following description, the state in which the heating pulse is ON will be referred to as pulse ON and heating pulse OFF. When the voltage of the heating pulse signal is High, the heating element 34 performs heating, and when the voltage of the heating pulse signal is Low, the heating element 34 does not perform heating. Therefore, color development on the print medium 10 is controlled by controlling the number of ON pulses included in the heating signal for each color. Note that in this embodiment, all heating pulse signals applied to sections a to Z have the same pulse width and the same voltage.

When activating (coloring) the yellow (Y) coloring layer in the print medium 10, it is necessary to perform heating that satisfies the coloring conditions shown in area 21 of FIG. Therefore, heating pulses are generated in each of sections a to j. In other words, pulse ON and pulse OFF are repeatedly generated in intervals a to interval j. Furthermore, in order to develop magenta (M), it is necessary to satisfy the color development conditions shown in the region 22 shown in FIG. 2, and therefore, pulse ON and pulse OFF are repeatedly generated in the interval a to interval y. Similarly, when developing cyan (C), pulse ON and pulse OFF are repeatedly generated in sections a to section W in order to satisfy the color development conditions of the region 23 shown in FIG. In this manner, by intervening the pulse OFF period between the pulse ON periods, it is possible to suppress the temperature of the print medium 10 from rising above the target temperature. That is, by controlling the pulse ON time and pulse OFF time, it is possible to maintain the target temperature. Note that in this embodiment, the pulse ON cycle is constant, but it is also possible to vary the pulse ON cycle.

To summarize the above, the relationships between the sections a to Z shown in FIG. 7 and the heating times t1 to t3 and heating temperatures Ta1 to Ta3 shown in FIG. 2 are as follows.

That is, the heating time required to exceed the activation temperature shown in FIG.
t2>Y heating time (section a to section j)>t1
t3>Heating time of M (section a to section y)>t2
Heating time of C (section a to section W) > t3
It becomes. Therefore, the relative relationship between the heating times required for color development of Y, M, and C is as follows:
Heating time for Y<heating time for M<heating time for C. Note that, as described above, the respective colors of Y, M, and C occur in the first to third image forming layers 14, 16, and 18.

The heating energy (heat amount) applied to the print medium 10 by the print head 30 is applied to the glaze 32 (and convex glaze 33), the base 31, and the base 31 of the print head 30 shown in FIG. The heat is conducted to the heat sink 35 and the like. Furthermore, the amount of heat thermally conducted into the print medium 10 also propagates around the platen 43 shown in FIG. 4 and the like. Therefore, the temperature of the print medium 10 decreases during the interval time. As a result, when the heating energy (heat amount) applied to the print medium 10 is the same, the peak temperature in each image forming layer 14, 16, 18 is
First image forming layer 14 > second image forming layer 16 > third image forming layer 18
becomes. Therefore, in order to cause the image forming layers 14, 16, and 18 to develop color, it is necessary to control the print head 30 so that the peak temperatures of the image forming layers have the following relationship.
Peak temperature of image forming layer 14 (Y)>Ta3
Ta3>Peak temperature of second image forming layer 16 (M)>Ta2
Ta2>Peak temperature of third image forming layer 18(C)>Ta1

By controlling the print head 30 so that the peak temperatures of each image forming layer have the above relationship, each of the colors Y, M, and C can be developed independently.

Next, a heating pulse signal for forming pixels of the Nth color will be explained. Here, the Nth-order color means a color that is a combination of N different colors. In this embodiment, by causing two or three of the first, second, and third image forming layers 14, 16, and 18 included in the print medium 10 to develop color at the same pixel position, secondary Forming color or tertiary color pixels. The secondary colors formed in this embodiment are red (R), green (G), and blue (B), and the tertiary color is black (K).

When forming red (R) pixels, a heating pulse signal train shown in (R) of FIG. 7 is applied to the heating element 34. As a result, yellow (Y) and magenta (M) are developed in this order, and pixels of red (R), which is a secondary color, can be formed.

When forming green (G) pixels, the heating pulse signal train shown in FIG. 7(G) is applied to the heating element 34 to develop yellow (Y) and cyan (C) in this order. let Similarly, when forming blue (B) pixels shown in FIG. 7, a heating pulse signal train shown in FIG. 7(B) is applied to the heating element 34, and magenta (M) and cyan (C) Develop the color in this order. In addition, when forming black (K) pixels shown in FIG. 7, a heating pulse signal train shown in FIG. (C) is colored in this order. As a result, black (K) pixels, which are a combination of three colors, are formed.

<Calculation flow of density unevenness correction value>
FIG. 8 is a flowchart showing the flow of processing for calculating density unevenness correction values according to this embodiment, and in the figure, broken line arrows indicate data transmission and reception. In FIG. 8, the processes in S801 to S804 are executed in the smartphone 50, and the processes in S811 to S815 are executed in the printing device 40. These processes are performed by a CPU provided in each device. That is, in the smartphone 50 that is the host device, the CPU 501 reads and executes the programs held in the HDD 503 and the RAM 502, thereby performing the processes of S801 to S804. Further, in the printing apparatus 40, the CPU 401 reads and executes the programs held in the ROM 403 and RAM 402, thereby performing the processes of S811 to S815.

When the user inputs an instruction to correct uneven density, the smartphone 50 transmits an instruction to create an uneven density correction value to the printing device 40 in S8011. Upon receiving the density unevenness correction instruction from the smartphone 50, the printing device 40 forms an image on the print medium 10 for detecting the heat generation characteristics of the heat generating element 34 (S811). The image for detecting the heat generating characteristics of the heat generating elements 34 is an image for detecting variations in the heat generating characteristics of the plurality of heat generating elements 34 provided in the print head 30, and the image data is It is held in ROM. Hereinafter, this image will be referred to as a detected image, and image data representing the detected image will be referred to as detected image data. This detected image will be explained later with reference to FIG. 9. When the printing process of the detected image is completed, the printing device 40 transmits a print completion notification to the smartphone 50 (S812) and enters a standby state.

Note that in S811, an example has been described in which the printing apparatus 40 reads out and prints the detected image data held in the ROM 403, but the present invention is not limited to this. The detected image data held in the HDD 503 of the smartphone 50 may be transmitted to the printing device 40, and the printing device 40 may print the received detected image.

In S802, the smartphone 50 receives the print completion notification transmitted from the printing device 40, and displays the received print completion notification on the display. Further, the smartphone 50 displays a message on the display of the smartphone 50 instructing the camera 46 of the printing device 40 to capture the detected image formed on the print medium 10, and prompts the user to capture the detected image (S803 ).

When the user presses the image capture button 47 of the printing device 40 in accordance with the message displayed on the smartphone 50, the printing device 40 captures a detected image formed on the print medium 10 using the camera 46 (S813). After that, in S814, the CPU 401 of the printing apparatus 40 analyzes the detected image captured by the camera 46, calculates a density unevenness correction value, and creates a correction table for density unevenness correction. The created density unevenness correction table is held in the RAM 402. Note that the details of the process of calculating the density unevenness correction value and creating the correction table will be described later. After that, the printing device 40 transmits a correction table creation completion notification to the smartphone 50 and enters a standby state (S815).

In S804, the smartphone 50 displays the correction table creation completion notification received from the printing device 40 on the display of the smartphone. This display allows the user to recognize that it is now possible to print an image that has been corrected for density unevenness. With the above steps, the density unevenness correction value and correction table creation process is completed.

Note that the above flowchart shows an example in which the detected image is captured by the camera 46 of the printing device 40 and the density unevenness correction value is calculated by the CPU (correction means) 401 of the printing device 40. However, processing such as capturing the detected image and calculating the density unevenness correction value can also be performed on the smartphone 50 side. For example, a detected image is captured by the camera 507 of the smartphone 50, the density unevenness correction value calculated by the CPU 501 of the smartphone 50 is transferred to the printing device 40, and the printing device 40 creates a correction table based on the received correction value, It may also be held in the RAM 402.

<Detected image>
Next, a detection image formed in this embodiment will be explained. FIG. 9 is a partially enlarged view showing an example of the detected image 1001 printed on the print medium 10. In the figure, the y direction is the print medium conveyance direction (the width direction of the print medium), and the x direction is a direction perpendicular to the print medium 10 conveyance direction. The plurality of heating elements 34 of the print head 30 that prints on the print medium 10 are arranged along the x direction.

A detection image 1001 shown in FIG. 9 is an image printed to detect the heat generation characteristics of the heat generating element 34, and is composed of a mark 1002 and analysis areas 1003 to 1008.

A plurality of marks 1002 are printed at predetermined intervals along the width direction (x direction) of the print medium. The plurality of marks 1002 are images used to specify the position of the heating element 34. It is preferable that the plurality of marks 1002 be formed by mainly coloring the first image forming layer 14, which develops color in the shortest heating time. This mark makes it possible to correlate the heating element 34 and the detected image with high precision when reading the printed detected image.

The analysis area 1003 is formed by high density yellow (Y): (R, G, B) = (255, 255, 0). Furthermore, in the analysis area 1004, low density yellow (Y): (R, G, B) = (255, 255, 128) is printed. In other words, these two analysis areas 1003 and 1004 are both areas where the first image forming layer 14 is mainly colored and printed, and the coloring heating characteristics of the first image forming layer 14 and the heating characteristics of the heating element 34 This is the area for detecting.

Similarly, the analysis area 1005 prints high-density magenta (M): (R, G, B) = (255, 0, 255). Furthermore, the analysis area 1006 prints low density magenta (M): (R, G, B) = (255, 128, 255). These two analysis areas 1005 and 1006 are areas for mainly detecting the heat-generating coloring heating characteristics of the second image forming layer 16 and the heat-generating characteristics of the heating element 34.

The analysis area 1007 is high density cyan (C): (R, G, B) = (0,255,255), and the analysis area 1008 is low density cyan (C) (R, G, B) = (128,255) , 255), and is an image mainly for detecting the characteristics of the third image forming layer 18.

In the present embodiment, an example has been described in which two typical gradations are printed in each of the image forming layers 14, 16, and 18, but the number of gradations in the area to be printed may be three or more.

By forming a detection image 1001 on the recording member 10, photographing it with a camera, and adjusting the number of ON pulses for each heating element 34, density unevenness in the direction in which the heating elements 34 are lined up (x direction) is suppressed.

FIG. 10 shows an example in which the number of ON pulses of the heating pulse signal is adjusted when printing is performed using the heating element 34 with the lowest applied voltage. In FIG. 9, as in FIG. 7, a heating pulse signal after correction (second heating signal) corresponding to the color desired to be developed in one pixel of the print medium 10 and a heating pulse signal before correction (first heating signal) are shown. A configuration example is shown. The voltage applied to the heating element 34 is V', and the relationship is V'<V. Here, as an example, V/V'=approximately 1.1.

FIG. 10 shows a high-density heating pulse signal and a low-density heating pulse signal as representative examples of heating pulse signals of each color. That is, from the top of FIG.
Heating pulse signal before density unevenness correction for high density yellow (Y) (first heating signal)
Heating pulse signal after density unevenness correction for high density yellow (Y) (second heating signal)
Heating pulse signal (first heating signal) before density unevenness correction for low density yellow (Y)
Heating pulse signal after density unevenness correction for low density yellow (Y) (second heating signal)
Heating pulse signal (first heating signal) before density unevenness correction for high density magenta (M)
Heating pulse signal after density unevenness correction for high density magenta (M) (second heating signal)
Heating pulse signal before density unevenness correction for low density magenta (M) (first heating signal)
Heating pulse signal after density unevenness correction for low density magenta (M) (second heating signal)
Heating pulse signal (first heating signal) before density unevenness correction for high density cyan (C)
Heating pulse signal after density unevenness correction for high density cyan (C) (second heating signal)
Heating pulse signal (first heating signal) before density unevenness correction for low density cyan (C)
Heating pulse signal after density unevenness correction for low density cyan (C) (second heating signal)
It is shown.

The heating pulse signal of high-density yellow (Y) before density unevenness correction shown in FIG. 10 has a lower voltage than the heating pulse signal of yellow (Y) shown in FIG. Therefore, although the heating pulse signal shown in FIG. 10 has the same number of ON pulses as the heating pulse signal shown in FIG. 7, the image density on the printing member 10 becomes thinner. Therefore, the heating pulse signal after density unevenness correction for high-density yellow (Y) shown in FIG. I'm letting you do it.

Similarly, the high density magenta (M) heating pulse signal shown in FIG. 10 before density unevenness correction has a lower voltage than the yellow (M) heating pulse signal shown in FIG. 7, so the number of ON pulses is the same. The image density on the printing member 10 is also reduced. Therefore, the number of ON pulses is increased so that the heating pulse signal of high density magenta (M) after density unevenness correction shown in FIG. I'm letting you do it.

Furthermore, the heating pulse signal of high-density cyan (C) shown in FIG. 10 before density unevenness correction is smaller and has a lower voltage than the heating pulse signal of cyan shown in FIG. The image density above No. 10 is thinner. Therefore, the number of ON pulses is increased so that the heating pulse signal after density unevenness correction for high density cyan (C) shown in FIG. 11 has approximately the same density as the heating pulse signal for cyan (C) shown in FIG. I'm letting you do it.

Further, as shown in FIG. 10, the yellow (Y) heating pulse signal has closer intervals between pulse ON pulses than magenta (M) and cyan (C). Therefore, it is not possible to increase the number of ON pulses so as to obtain substantially the same concentration as the heating pulse signal shown in FIG. 7 in sections a to j. In other words, the required heat flux cannot be obtained by the heating time from section a to section j. Therefore, in the example shown in FIG. 10, correction is performed to increase the print density by widening the sections like sections a to m and increasing the number of ON pulses.

On the other hand, magenta (M) and cyan (C) have wide pulse intervals between pulse ONs, so the number of pulses ON is increased within the same interval (heating time) as the heating pulse signal shown in Figure 7. A correction is made to increase the heat flux. This makes it possible to print magenta (M) and cyan (C) with substantially the same density as the heating pulse signal shown in FIG.

In addition, in the example shown in FIG. 10, for yellow (Y), the number of ON pulses in the heating pulse signal before density unevenness correction for high density yellow (Y) is 10, and the number of pulses ON in the heating pulse signal after density unevenness correction is 10. It is now 13. In other words, the number of pulses ON after correction is increased by 1.3 times the number of pulses ON before correction. On the other hand, the rate (ratio) of decrease in voltage V' with respect to voltage V is approximately 1.1, and the rate of increase in the number of ON pulses is greater than the rate of decrease in voltage.

Furthermore, for magenta (M), the number of ON pulses of the heating pulse signal before density unevenness correction for high density magenta (M) is 7, and the number of pulses ON for the heating pulse signal after density unevenness correction for high density magenta (M) is 8. It is. In other words, the rate at which the number of ON pulses increases due to the correction is 1.1, which is approximately the same as the rate at which the voltage V' decreases with respect to the voltage V (approximately 1.1).

Similarly, for cyan (C), the number of ON pulses of the heating pulse signal before density unevenness correction for high density cyan (C) is 9, and the number of ON pulses of the heating pulse signal after density unevenness correction for high density cyan (C). is 11, and the rate at which the number of ON pulses increases due to correction is 1.1. Therefore, in cyan (C) as well, the rate at which the number of ON pulses increases due to correction and the rate at which voltage V' decreases with respect to voltage V (approximately 1.1) are approximately the same.

In this way, the number of ON pulses (i.e., heating energy) increases.

In addition, the number of pulses ON in the heating pulse signal before density unevenness correction for low density yellow (Y) is 5, and the number of pulses ON in the heating pulse signal after density unevenness correction for low density yellow (Y) is 6. The rate at which the number of pulses ON is increased is 1.2. In other words, the rate of change in the number of ON pulses (density unevenness correction value) due to correction is larger for high density yellow (Y) than for low density yellow (Y).

As described above, the rate of change in the number of ON pulses is calculated for each gradation for yellow (Y), magenta (M), and cyan (C), and the results are used as the respective density unevenness correction values. The target density used in calculating the density unevenness correction value may be set to the density printed by the heating element 34 to which the applied voltage is close to the center value among the plurality of heating elements 34, or to the density printed by the heating element 34 to which the applied voltage is the lowest. The density may be set to the density printed in step 34.

In order to develop cyan (C), magenta (M), and yellow (Y) colors at desired densities, it is necessary to correct the heating energy generated by each heating element 34 using the density unevenness correction value described above. . In the present embodiment, density unevenness correction values for correcting each of the c, m, and y data representing the pulse number and pulse width of the heating pulse signal applied to each heating element 34 are created as 1D_LUT and held in the printing device 40. are doing. That is, 1D_LUT_C for correcting c data, 1D_LUT_M for correcting m data, and 1D_LUT_Y for correcting y data are created for each heating element 34 and held in the ROM 403 of the printing device 40. Thereby, the heating energy of each gradation of c, m, and y data can be appropriately corrected. Note that since the Nth color is a combination of yellow (Y), magenta (M), and cyan (C), density unevenness correction values for each of yellow (Y), magenta (M), and cyan (C) are applied. .

Furthermore, since FIG. 10 shows an example of correcting the heating pulse signal of the heating element 34 where the applied voltage is lower than the average, the number of ON pulses of the heating pulse signal is increased in the correction, but the applied voltage is lower than the average. When correcting the heating element 34 with a large voltage, the correction is performed to reduce the number of ON pulses of the heating pulse signal.

<Image processing>
FIG. 11 is a flowchart showing the flow of image processing performed in this embodiment. The processing executed in each step of FIG. 11 is executed in step S615 of the flowchart of FIG. The processing shown in FIG. 11 is realized, for example, by the CPU 401 of the printing device 40 reading and executing programs and data contained in the ROM 403 and the like. That is, in this embodiment, the CPU 401 functions as a generation unit that generates a heating signal that is print data. Note that some of the functions shown in FIG. 11 can also be executed by an ASIC such as the image processing accelerator 407.

In S1101, the CPU 401 acquires the image data in the print job received in S614 of FIG. Here, the explanation will be given assuming that image data is acquired page by page.

In S1102, the CPU 401 performs decoding processing on compressed or encoded image data. Note that if the image data is not compressed or encoded, this process is omitted. Through the decoding process, the image data becomes RGB data. Examples of the type of RGB data include standard image data such as sRGB and Adobe (registered trademark) RGB. The image data in this embodiment has 8 bits of information for each color and has a value range of "0" to "255", but the image data is composed of 16 bits of information or other number of bits of information. It may be data.

In S1103, the CPU 401 performs color correction processing on the image data. Note that the color correction process can also be performed on the smartphone 50 side. However, when performing color correction tailored to the printing device 40, it is preferable to perform it within the printing device 40 as in this example. The image data after the color correction process is RGB data, but at this point it is assumed to be in the format of RGB specialized for the printing apparatus 40, so-called device RGB.

In S1104, the CPU 401 performs brightness density conversion on the image data using a three-dimensional lookup table. In a typical thermal printing device, for example, the following conversion is performed using RGB data of image data.
C=255-R
M=255-G
Y=255-B

On the other hand, in the case of the pulse control according to the present embodiment, for example, the control parameters for magenta when magenta (M) is configured as a single color and the control parameters for magenta that configures red (R), which is a secondary color, are different. Therefore, in order to set both separately, it is preferable to perform brightness density conversion using a three-dimensional lookup table shown below.

In this embodiment, brightness density conversion is performed using a three-dimensional lookup table shown below. In the three-dimensional lookup table function 3D_LUT[R][G][B][N] shown below, variables R, G, and B are input with RGB data values, respectively, and variable N is used to output C, M, Either Y is specified. Here, it is assumed that 0, 1, and 2 are designated as C, M, and Y, respectively.
C=3D_LUT[R][G][B][0]
M=3D_LUT[R][G][B][1]
Y=3D_LUT[R][G][B][2]

The above 3D_LUT is composed of 50331648 data tables of 256×256×256×3. Each data corresponds to the pulse width applied in each of sections a to Z shown in FIG. 7. In addition, in order to reduce the amount of data in the lookup table, for example, the number of grids is reduced from 256 to 17, and 14,739 data tables of 17 x 17 x 17 x 3 are used, and the values between grids are calculated by interpolation. It may be calculated. In addition to 17 grids, it is also possible to set a suitably suitable number of grids, such as 16 grids, 9 grids, and 8 grids. As the interpolation method, a known method such as tetrahedral interpolation may be used. In this embodiment, the three-dimensional lookup table is defined in advance and stored in the ROM 403 of the printing device 40 or the like.

By using the above three-dimensional lookup table, the control parameters for each of yellow (Y), magenta (M), and cyan (C) that constitute each printing color can be individually set. That is, yellow (Y) and magenta (M) make up red (R) which is a secondary color, cyan (C) and yellow (Y) make up green (G), and magenta (make up blue (B)). It becomes possible to independently set control parameters for each of M) and cyan (C). Similarly, control parameters for each of yellow (Y), magenta (M), and cyan (C) constituting black (K) can also be set independently. This enables more fine control of color development and contributes to improved color reproducibility.

In S1105, the CPU 401 performs output correction on the converted image data. First, the CPU 401 uses a conversion table corresponding to each print color to indicate the ON number of heating pulse signals and the pulse ON interval corresponding to the C, M, and Y values. It is assumed that this conversion table (conversion formula) is defined in advance and stored in the ROM 403 of the printing device 40 or the like.
c=1D_LUT[C]
m=1D_LUT[M]
y=1D_LUT[Y]

By correcting the pulse ON number and the pulse ON interval indicated by c, m, and y, it becomes possible to modulate the coloring intensity in the print medium 10, and realize the density corresponding to the desired gradation. I can do it.

Furthermore, CPU 401 modulates the heating pulse according to the temperature of print medium 10 or print head 30 acquired by temperature sensor 45 . Specifically, as the temperature detected by the temperature sensor 45 becomes higher, the number of ON pulses of the heating pulse used to reach the activation temperature is controlled to be reduced. This process can be performed using known means. Further, the temperature of the print medium 10 can also be acquired by a device other than the temperature sensor 45. For example, in the smartphone 50 or the printing device 40, it is also possible to obtain the temperature by estimating the temperature of the print medium 10 or the print head 30, and control the number of ON pulses of the heating pulse signal based on the obtained estimated temperature. Good too. The method for estimating this temperature is not particularly limited, and any known method can be used.

In S1106, the CPU 401 converts the c, m, and y data generated in S1105 into c', m', and y' data as density unevenness correction values using the following conversion table created for each heating element 34 ( performs processing as a derivation means. That is, the CPU 401 converts (derives) the pulse ON number and pulse ON interval indicated by the c, m, and y data into the pulse ON number and pulse ON interval indicated by the c', m', and y' data. .
c'=1D_LUT_C[c]
m'=1D_LUT_M[m]
y'=1D_LUT_Y[y]

Thereafter, in step S1107, the CPU 401 controls the print head 30 via the head controller 405 based on the number of ON pulses and the interval between ON pulses derived by referring to the above conversion table. At this time, yellow (Y), magenta (M), and cyan (C) heating pulse signals whose density unevenness is controlled based on the correction value are applied to each heating element 34, and each pixel of the printing medium 10 is Provides heating to the area. This allows each pixel area on the print medium 10 to develop a desired color.

In S1108, the CPU 401 determines whether printing of one page is completed. If completed (YES in S1108), this process flow is ended and the process proceeds to the next page or to the process of S616 in FIG. 6. If printing for one page has not been completed (NO in S1108), the process advances to S1101 to continue image formation processing for the page.

As described above, in this embodiment, in order to perform density unevenness correction according to the heat generation characteristics of each heating element 34 of the print head 30 and the coloring heating characteristics of each image forming layer 14, 16, 18 of the print medium 10, multiple It becomes possible to form a high-quality image on a print medium on which image forming layers are laminated.

<Second embodiment>
In the first embodiment described above, as shown in FIG. 11, c data, m An example has been described in which data and y data are corrected independently by applying 1D_LUT to each. When forming monochrome pixels on the print medium 10, as shown in FIG. 10, the heating pulse signal must be kept within the heatable time (section a to Z) determined for forming one pixel. I can do it. However, when forming pixels of the Nth color, there is a possibility that the heating pulse signal does not fit within the heating possible time. In particular, when forming pixels of the Nth color, if the pulse ON signal of the heating pulse signal is corrected to increase independently for each color, the heating pulse signal of each color is sequentially applied to the print medium. . For this reason, there is a possibility that the heating pulse signals for all colors for forming the N-th color cannot be received within the heating time.

Therefore, in this embodiment, the c data, m data, and y data are corrected by applying 3D_DLUT. This will be explained below with reference to FIG. Note that in FIG. 11, steps S1101 to S1105 and steps S1107 to S1108 are the same as the processes described in the first embodiment, so their explanations will be omitted.

In the density unevenness correction process of the first embodiment described above, the number of ON pulses of the heating pulse signal of the heating element 34 to which the applied voltage is lowest is increased, and this may be a factor that causes the heating pulse signal to exceed the possible heating time. There is. Therefore, in this embodiment, the heating element 34 with the lowest heating voltage is set as the reference heating element 34. Furthermore, correction to suppress density unevenness is performed using 3D_LUT_ which is a combination of c, m, and y data. In this combination of c, m, y data, if the heating pulse signal does not fall within the range a to Z, the corrected rate of change (of the number of pulses ON) of the c data with the longest heating time among the c, m, y data. rate of change) to keep the heating pulse signal within the heating pulse time.

In this way, correction values corresponding to all combinations of c, m, and y data are calculated for the reference heating element 34 and held in the 3D_LUT. Note that for other heating elements 34 with higher applied voltages, correction values are calculated so that substantially the same heating energy as that of the reference heating element 34 is obtained, and the correction values are held in the 3D_LUT. In this way, a 3D_LUT is created for each heating element 34 and stored in the ROM 403.

In S1106, the c, m, and y data are converted into c', m', and y' data according to the heating characteristics of each heating element 34 using the following conversion table created for each heating element 34.
c'=3D_LUT[c][m][y][0]
m'=3D_LUT[c][m][y][1]
y'=3D_LUT[c][m][y][2]

The above 3D_LUT may be 50331648 data tables of 256 x 256 x 256 x 3, or a suitable number of grids may be set as appropriate, for example, 17 grids, 16 grids, 9 grids, or 8 grids. The data corresponding to each grid is a value for correcting the c, m, and y data. Furthermore, any method such as known tetrahedral interpolation may be used as a method for interpolating data between grids. In this embodiment, it is assumed that the three-dimensional lookup table is defined in advance and stored in the ROM 403 of the printing device 40 or the like. By using the above three-dimensional lookup table, it is possible to correct the c, m, and y data by giving them a dependency relationship, and the heating pulse signal of each color can be corrected within the heating possible time of one pixel (section a to Z). It becomes possible to contain it.

(Third embodiment)
Next, a third embodiment of the present disclosure will be described. This embodiment also includes the configuration shown in FIGS. 3 to 5, and is assumed to print on the print medium 10 shown in FIG. 1. Hereinafter, the explanation will focus on the differences from the first embodiment.

In the above embodiment, as shown in FIG. 8, an example was shown in which the heating pulse signal converted into c, m, and y data is corrected. In contrast, in this embodiment, density unevenness is corrected by correcting the pixel values RGB.

The image forming process executed in this embodiment will be described below with reference to the flowchart in FIG. 12. Note that S1201 to S1203 and S1205 to S1208 shown in FIG. 12 are the same as S1101 to S1103, S1105, S1107, and S1108 shown in FIG. 11, and redundant explanation with the first embodiment will be omitted.

In this embodiment as well, in the calculation process of the density unevenness correction value, the heating element 34 with the lowest applied voltage is used as the reference heating element, and the heating characteristics of the reference heating element 34 and the RGB data are used as in the first embodiment. The color that will be produced is calculated based on the c, m, and y data converted from . This calculation is performed for all 256×256×256=16777216 RGB data combinations, and these colors are set as target colors. Similarly, the colors that will be produced in other heating elements 34 are calculated based on the heating element characteristics and the c data, m data, and y data converted from the RGB data for all RGB combinations.

Next, for the other heating elements 34, correspondence is made with RGB combinations that give substantially the same color as the reference heating element 34 in all RGB combinations (16777216 combinations), and are held as a 3D_LUT. This 3D_LUT is created for each heating element 34. The 3D_LUT may be 50331648 data tables of 256 x 256 x 256 x 3, or a suitable number of grids may be set as appropriate, for example, 17 grids, 16 grids, 9 grids, or 8 grids. A known method such as tetrahedral interpolation may be used for interpolating values between grids.

In the density unevenness correction processing performed in S1304 of the present embodiment, the pixel values RGB are corrected instead of correcting c data, m data, and y data as in the density unevenness correction processing performed in S1106 of the first embodiment. This embodiment differs from the first embodiment in this point. The pixel values RGB are converted using the following conversion table created for each heating element 34.
R'=3D_LUT[R][G][B][0]
G'=3D_LUT[R][G][B][1]
B'=3D_LUT[R][G][B][2]

As described above, in this embodiment, the image value RGB is corrected according to the heat generation characteristics of each heating element 34 of the print head 30 and the coloring heating characteristics of each image forming layer 14, 16, 18 of the print medium 10. This makes it possible to reduce density unevenness due to variations in the heating characteristics of the heating elements 34.

<Other embodiments>
In the above embodiment, an example was shown in which the process of deriving the density unevenness correction value, the process of creating the correction table, etc. is performed by the CPU 401 of the printing device 40, but these processes can also be performed by the smartphone 50, which is the host device. It is. For example, the heat generation characteristics of each heating element 34 may be transmitted from the printing device 40, and the density unevenness correction value or correction table may be derived by the CPU 501 of the smartphone 50 based on the heat generation characteristics. In this case, by transmitting the obtained density unevenness correction value or correction table to the printing device 40 and having the printing device 40 hold it, it is possible to reduce the load required for processing by the printing device 40.

Further, the present disclosure provides a system or device with a program that implements one or more functions of the above embodiments via a network or a storage medium, and one or more processors in a computer of the system or device reads the program. It can also be realized by executing processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Note that the present disclosure includes the following configurations, methods, and programs.

(Configuration 1)
A printing device comprising a plurality of heating elements that apply heating energy to a printing medium in which a plurality of coloring layers that develop different colors when different heating energies are applied to a printing medium, the printing device comprising:
acquisition means for acquiring heat generation characteristics of each of the plurality of heating elements;
generating means for generating print data for generating the heating energy in each of the plurality of heat generating elements based on the color heating characteristics and the heat generation characteristics of each of the plurality of color forming layers based on image data corresponding to a pixel; ,
A printing apparatus comprising: drive control means for causing each of the plurality of heating elements to generate the heating energy based on the print data.

(Configuration 2)
The acquisition means reads the density of a single-color detection image formed on the printing medium by the plurality of heating elements, and obtains the heating characteristics of each of the plurality of heating elements based on the read density. The printing device according to configuration 1.

(Configuration 3)
3. The printing apparatus according to configuration 1 or 2, wherein the heat generation characteristic represents an amount of heating energy generated by the heating element for predetermined print data.

(Configuration 4)
The generating means generates a second heating signal by correcting a predetermined first heating signal according to the heating characteristics of each of the plurality of heating elements, based on the coloring heating characteristics of each of the plurality of coloring layers. 4. The printing apparatus according to any one of configurations 1 to 3, further comprising a correction unit that generates the second heating signal and outputs the second heating signal as the print data.

(Configuration 5)
The correction means may increase the ratio of the heating energy generated by the heating element by the first heating signal to the heating energy generated by the heating element by the second heating signal as the density to which the print medium is to be colored increases. 4. The printing apparatus according to configuration 4, wherein the second heating signal is corrected so that the second heating signal becomes .

(Configuration 6)
The generating means includes a table provided with correction values for performing correction according to heat generation characteristics of the heating element for each combination of the three heating energies applied to each of the three coloring layers corresponding to the same pixel. according to configuration 4 or 5, wherein the second heating signal is generated by correcting the first heating signal that generates heating energy to be applied to each of the three coloring layers corresponding to each pixel of the printing medium. printing device.

(Configuration 7)
The heating element generates the heating energy by applying a voltage,
The first heating signal and the second heating signal are composed of a plurality of voltage pulses that apply voltage to the heating element,
Configuration 4, characterized in that the correction means generates the second heating signal by correcting at least one of the number of pulses and the pulse interval of the voltage pulses constituting the first heating signal according to the heat generation characteristic. 7. The printing device according to any one of 6 to 6.

(Configuration 8)
8. The printing apparatus according to configuration 7, wherein the pulse width and the number of pulses of the voltage pulse define a heating temperature and a heating time at which the printing medium is heated by the heating element.

(Configuration 9)
Structure 7, wherein the correction means increases the number of pulses of the voltage pulses constituting the second heating signal as the heating element generates a smaller amount of heating energy among the plurality of heating elements. 8. The printing device according to 8.

(Configuration 10)
The correction means calculates a correction value for correcting at least one of the number of pulses and the pulse interval of the voltage pulses constituting the first heating signal for each gradation value of a plurality of colors corresponding to the color forming layer. 10. The printing apparatus according to any one of configurations 7 to 9, wherein the first heating signal is corrected using a correction table defined in .

(Configuration 11)
The printing apparatus according to configuration 1, wherein the generating means changes pixel values of the image data in order to suppress density unevenness.

(Configuration 12)
Any one of configurations 1 to 11, wherein the printing medium includes a first coloring layer that develops yellow, a second coloring layer that develops cyan, and a third coloring layer that develops magenta. Printing device as described.

(Configuration 13)
The printing medium is characterized in that the first coloring layer, the second coloring layer, and the third coloring layer are sequentially laminated from the side to which the heating energy is applied by the heating element. 13. The printing device according to 12.

(Configuration 14)
The detected image includes a region of the plurality of coloring layers that is printed when the heating time by the heating element is shorter than a predetermined time and the heating temperature is higher than a predetermined temperature, and a region of the plurality of coloring layers that is printed when the heating time by the heating element is shorter than a predetermined time and the heating temperature is higher than a predetermined temperature. The printing apparatus according to configuration 2, further comprising at least an area that is printed when the heating temperature by the heat generating element is longer than the predetermined time and is lower than or equal to the predetermined temperature.

(Configuration 15)
14. The printing apparatus according to any one of configurations 1 to 13, further comprising a conveyance means for conveying the print medium in a direction intersecting a direction in which the plurality of heat generating elements are arranged.

(Method 1)
A printing method in which an image is printed by applying heating energy using a plurality of heating elements to a printing medium in which a plurality of coloring layers that develop different colors when different heating energies are applied are stacked, ,
an acquisition step of acquiring heat generation characteristics of each of the plurality of heat generating elements;
a generation step of generating print data for causing each of the plurality of heating elements to generate the heating energy based on image data corresponding to a pixel, based on the coloring heating characteristics and the heating characteristics of each of the plurality of coloring layers; and,
A printing method comprising: a drive control step of causing each of a plurality of heating elements to generate the heating energy based on the printing data.

(Program 1)
A program for causing a computer to execute each step described in Method 1.

10 Print medium 14 First image forming layer 16 Second image forming layer 18 Third image forming layer 34 Heat generating element 40 Printing device 46 Camera 401 CPU

Claims (17)

A printing device comprising a plurality of heating elements that apply heating energy to a printing medium in which a plurality of coloring layers that develop different colors when different heating energies are applied to a printing medium, the printing device comprising:
acquisition means for acquiring heat generation characteristics of each of the plurality of heating elements;
generating means for generating print data for generating the heating energy in each of the plurality of heat generating elements based on the color heating characteristics and the heat generation characteristics of each of the plurality of color forming layers based on image data corresponding to a pixel; ,
A printing apparatus comprising: drive control means for causing each of the plurality of heating elements to generate the heating energy based on the print data. The acquisition means reads the density of a single-color detection image formed on the printing medium by the plurality of heating elements, and obtains the heating characteristics of each of the plurality of heating elements based on the read density. The printing device according to claim 1. 3. The printing apparatus according to claim 1, wherein the heat generation characteristic represents an amount of heating energy generated by the heating element for predetermined print data. The generating means generates a second heating signal by correcting a predetermined first heating signal according to the heating characteristics of each of the plurality of heating elements, based on the coloring heating characteristics of each of the plurality of coloring layers. The printing apparatus according to claim 1, further comprising a correction unit that generates the second heating signal and outputs the second heating signal as the print data. The correction means may increase the ratio of the heating energy generated by the heating element by the first heating signal to the heating energy generated by the heating element by the second heating signal as the density to which the print medium is to be colored increases. 5. The printing apparatus according to claim 4, wherein the second heating signal is corrected so that the second heating signal is corrected so that the second heating signal is corrected so that the second heating signal is corrected so that the second heating signal is corrected so that The generating means includes a table provided with correction values for performing correction according to heat generation characteristics of the heating element for each combination of the three heating energies applied to each of the three coloring layers corresponding to the same pixel. 6. The second heating signal is generated by correcting the first heating signal that generates heating energy to be applied to each of the three coloring layers corresponding to each pixel of the printing medium. Printing device as described. The heating element generates the heating energy by applying a voltage,
The first heating signal and the second heating signal are composed of a plurality of voltage pulses that apply voltage to the heating element,
2. The correcting means generates the second heating signal by correcting at least one of the number of pulses and the pulse interval of the voltage pulses constituting the first heating signal in accordance with the heat generation characteristic. 4. The printing device according to 4. 8. The printing apparatus according to claim 7, wherein the pulse width and the number of pulses of the voltage pulse define a heating temperature and a heating time at which the printing medium is heated by the heating element. 7. The correcting means increases the number of pulses of the voltage pulses constituting the second heating signal for a heating element that generates less heat from the heating energy among the plurality of heating elements. Or the printing device according to 8. The correction means calculates a correction value for correcting at least one of the number of pulses and the pulse interval of the voltage pulses constituting the first heating signal for each gradation value of a plurality of colors corresponding to the color forming layer. 8. The printing apparatus according to claim 7, wherein the first heating signal is corrected using a correction table defined in . 2. The printing apparatus according to claim 1, wherein the generating means changes pixel values of the image data in order to suppress density unevenness. The printing device according to claim 1, wherein the printing medium includes a first coloring layer that develops yellow, a second coloring layer that develops cyan, and a third coloring layer that develops magenta. . A claim characterized in that the first coloring layer, the second coloring layer, and the third coloring layer are sequentially laminated on the printing medium from the side to which the heating energy is applied by the heating element. 13. The printing device according to item 12. The detected image includes a region of the plurality of color forming layers that is printed when the heating time by the heating element is shorter than a predetermined time and the heating temperature is higher than a predetermined temperature, and a region of the plurality of coloring layers that is printed when the heating time by the heating element is shorter than a predetermined time and the heating temperature is higher than a predetermined temperature. 3. The printing apparatus according to claim 2, further comprising at least an area that is printed when the heating temperature by the heating element is longer than the predetermined time and lower than the predetermined temperature. The printing apparatus according to claim 1, further comprising a conveyance means for conveying the print medium in a direction intersecting a direction in which the plurality of heating elements are arranged. A printing method in which an image is printed by applying heating energy using a plurality of heating elements to a printing medium in which a plurality of coloring layers that develop different colors when different heating energies are applied are stacked, ,
an acquisition step of acquiring heat generation characteristics of each of the plurality of heat generating elements;
a generation step of generating print data for causing each of the plurality of heating elements to generate the heating energy based on image data corresponding to a pixel, based on the coloring heating characteristics and the heating characteristics of each of the plurality of coloring layers; and,
A printing method comprising: a drive control step of causing each of a plurality of heating elements to generate the heating energy based on the printing data. A program for causing a computer to execute each step according to claim 16.

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