JP7492907B2 - Printing system, printing device, and method for printing test patterns - Google Patents

Description

This invention relates to a printing system, printing device, and test pattern printing method that can form an ink layer, form a transparent protective layer on top of it, print an image pattern, and further form a test pattern for calibration.

2. Description of the Related Art A calibration function is known for standardizing characteristics between individual devices relating to density, gamma characteristics, color tone, etc. of printing devices, and for stabilizing the characteristics over time and with respect to the environment.
This function stores a specified test pattern in the memory of the printing device, prints the stored test pattern when performing calibration, and has the printed test pattern read by a scanner (image reading unit) to make corrections to approach the target characteristics.

Scanners are generally flatbed types that are operated by placing an original (or a printed test pattern, in the case of calibration) on a transparent reading surface.
Regarding the calibration function, a scan data acquisition device and a correction data generation method have been proposed that can detect the orientation of a test pattern image and calculate correction data regardless of the orientation of the test pattern used to calculate the correction function relative to the reading surface (for example, Patent Document 1).

A method has also been proposed in which a reference document is read to determine the reading characteristics of a color image reading device for the reference document, and the reading characteristics for a specific document type are estimated based on this, and gamma conversion and color conversion parameters for the specific document are set (see, for example, Patent Document 2). Since the reading characteristics of a color scanner differ for each document type, this method aims to obtain stable color reproduction without the trouble of reading a standard document for each document type and setting color conversion coefficients.

However, when scanning a test pattern with a flatbed scanner, unevenness in density and color can occur. This occurs when scanning a test pattern printed on smooth glossy paper or a test pattern with a smooth surface made by an overcoated protective layer. The unevenness in density and color is caused by a phenomenon known as Newton's rings. That is, the surface of the test pattern is smooth but slightly wavy. With such a test pattern placed on a transparent, flat reading surface, the scanner reads the reflected light of the test pattern from below through the reading surface. The gradually changing distance between the reading surface and the surface of the test pattern creates shading in the scanned image that is not present in the original.

The general explanation for Newton's rings is that concentric stripes occur when a flat surface and a lens with a large radius of curvature on one side are placed close together. The test pattern above does not have a constant radius of curvature but an irregular undulation, so irregular shapes occur instead of concentric stripes.
The above-mentioned Patent Documents 1 and 2 make no mention of unevenness caused by the Newton ring phenomenon. In relation to this, an image reading device that reads transparent originals such as photographic film has been proposed in which a transparent platen that presses and positions one side of the film original is used as a diffusing surface (see, for example, Patent Document 3). It is stated that Newton rings occur when a minute gap is formed between the photographic film and the platen, and that the Newton rings can be prevented by making the platen a diffusing surface.

However, at the same time, it is also stated that if a diffusing surface of a transparent plate is present on the optical path from the photographic film to the image sensor, the diffusing surface will diffuse the light transmitted through the photographic film, causing the optical image to become blurred. On the other hand, even if a diffusing surface is present on the optical path from the light source to the photographic film, the transmitted light image will not become blurred. Therefore, a diffusing surface is placed on the optical path from the light source to the photographic film. In the case of a transparent original, such a configuration is possible, but in the case of a reflective original, not only the light incident on the original surface but also the light reflected from the original surface will pass through the same diffusing surface, resulting in a blurred optical image.

JP 2006-339688 A Japanese Patent Application Laid-Open No. 9-0186892 JP 2006-064714 A

When scanning originals with smooth surfaces such as silver halide photographs, there are known products that prevent adhesion by spraying a starch-based powder to prevent unevenness caused by the Newton ring phenomenon described above (for example, [online], [searched October 6, 2020], Internet <URL: https://www.str-web.com/product/ap.html>). However, these products require wiping after use, which is time-consuming and costly.

Various studies have been conducted to improve the accuracy of calibration, as in Patent Documents 1 and 2, but there is no mention of unevenness caused by the Newton's ring phenomenon and how to deal with it.
This invention has been made in consideration of the above circumstances, and provides a method for suppressing the appearance of uneven density and color caused by the Newton's ring phenomenon in the read image when a calibration test pattern having a smooth surface is read with a scanner.

This invention provides a printing system that includes a printing device and an image reading device, the printing device including a printing unit that forms a pattern on the surface of a printing medium using an ink layer and forms a transparent protective layer on the formed ink layer, and a control unit that uses the printing unit to form a test pattern and an image pattern for calibration, the image reading device including an image reading unit that optically reads the formed test pattern, and the control unit that, when forming the image pattern, forms a protective layer that covers the image pattern, and, when forming the test pattern, controls so that no protective layer is formed at least in the area where the test pattern is formed, or forms a protective layer that is less uniform than the protective layer that covers the image pattern, at least in the area where the test pattern is formed.

In a different aspect, the present invention provides a printing device that includes a printing unit that forms a pattern on the surface of a printing medium using an ink layer and forms a transparent protective layer on the formed ink layer, and a control unit that uses the printing unit to form a test pattern and an image pattern for calibration, and the control unit controls the printing device to form a protective layer that covers the image pattern when the image pattern is formed, and to form no protective layer at least in the area where the test pattern is formed, or to form a protective layer that is less uniform than the protective layer that covers the image pattern, at least in the area where the test pattern is formed.

From a different perspective, the present invention provides a method for printing a test pattern, comprising the steps of: a control unit of a printing device that forms a test pattern and an image pattern for calibration, using a printing unit to form a pattern of an ink layer on the surface of a printing medium; forming a transparent protective layer on the formed ink layer; and using an image reading unit to optically read the formed test pattern, and the control unit controls the control unit to form a protective layer that covers the image pattern when the image pattern is formed, and to not form a protective layer at least in the area where the test pattern is formed, or to form a protective layer that is less uniform than the protective layer that covers the image pattern, at least in the area where the test pattern is formed.

In the printing system of the present invention, the control unit controls so that, when the image pattern is formed, a protective layer covering the image pattern is formed, and, when the test pattern is formed, either no protective layer is formed or a protective layer that is more non-uniform than the protective layer covering the image pattern is formed, thereby suppressing density unevenness due to the Newton's ring phenomenon when a calibration test pattern having a smooth surface is read by a scanner.
The printing apparatus and printing method according to the present invention also provide the same advantageous effects.

FIG. 1 is a block diagram showing a configuration of an image forming system including a multifunction peripheral and a service unit in this embodiment. FIG. 2 is an external view of the image forming system shown in FIG. 2 is an explanatory diagram showing a state in which the scanner unit shown in FIG. 1 starts scanning an original; FIG. 3B is an explanatory diagram showing a state in which the scanner unit shown in FIG. 3A is scanning a document; FIG. 2 is an explanatory diagram showing a main part of the photoprinter printing unit shown in FIG. 1 . 10 is an explanatory diagram showing an example of a read image read by irradiating light from below an original placed on a platen glass in this embodiment. FIG. 10 is an explanatory diagram showing an example in which a read image of a test pattern contains unevenness due to the Newton's ring phenomenon in this embodiment. FIG. FIG. 2 is an explanatory diagram showing an example of a normal print output printed by a photo printer in this embodiment. 10 is an explanatory diagram showing an example of an output of a test pattern for calibration printed by a photo printer in this embodiment. FIG. FIG. 11 is an explanatory diagram showing an example in which a test pattern is printed on the surface of photo paper having projections and recesses formed on the surface. FIG. 10 is an explanatory diagram showing an example in which a test pattern is printed on the surface of photo paper that has been smoothly finished.

The present invention will be described in more detail below with reference to the drawings. Note that the following description is illustrative in all respects and should not be construed as limiting the present invention.
(Embodiment 1)
Configuration of the image forming system
First, the image forming system in this embodiment will be described.
Fig. 1 is a block diagram showing the configuration of a system including a multifunction peripheral and a service unit as one aspect of an image forming system in this embodiment Fig. 2 is an external view of the image forming system shown in Fig. 1.

1, the image forming system 100 is roughly divided into an MFP 101 and a service unit 110 based on its appearance. The MFP 101 constituting the image forming system 100 includes an MFP control unit 11, an MFP operation unit 12, a scanner unit 13, an MFP print unit 14, an MFP data storage unit 15, and an MFP communication interface circuit 16.
The multifunction device control unit 11 is composed of circuits centered around a processor, and the processor executes a control program stored in the multifunction device data storage unit 15 to control each unit of the multifunction device 101. The multifunction device control unit 11 cooperates with a service control unit 111 to provide services of the image forming system 100 using the multifunction device 101.

The multifunction machine operation unit 12 includes a display device such as a liquid crystal display device that provides information to the user, and an operation detection device such as a touch panel that receives operations from the user.
The scanner unit 13 is a flatbed type color scanner.
3A and 3B are explanatory diagrams showing the state in which the scanner unit 13 scans an original document. Fig. 3A shows the state in which scanning of the original document is started, and Fig. 3B shows the state in which the original document is being scanned.
As shown in FIGS. 3A and 3B, the original 31 is placed at a predetermined position with the reading surface facing the transparent platen glass 33.
The scanner unit 13 includes a light source 20 that illuminates the original 31, and a first scanning unit 21 that supports a first reflecting mirror that guides the light reflected from the original 31 illuminated by the light source 20. The scanner unit 13 further includes a second scanning unit 22 that supports second and third reflecting mirrors.

3A and 3B to scan the original 31 while illuminating the original 31 with the light source 20. At the same time, the second scanning unit 22 moves in the scanning direction at half the speed of the first scanning unit 21.
The light reflected from the original 31 is reflected by the first to third reflecting mirrors, passes through the imaging lens 23, and forms an image on the line image sensor 24. The line image sensor 24 reads the line-shaped image of the original 31. The first scanning unit 21 and the second scanning unit 22 move to scan the original 31, so that the line image sensor 24 reads the image of the entire surface of the original 31.

The multifunction printer printing unit 14 is an electrophotographic color print engine.
The multifunction device data storage unit 15 includes a non-volatile memory for storing the processing programs executed by the multifunction device control unit 11 and a RAM for storing data.
The multifunction device communication interface circuit 16 is an interface circuit for communicating with the service unit 110 and external devices (not shown).

2, the service unit 110 is disposed adjacent to the left side of the multifunction device 101. The service unit 110 includes a service control unit 111, a service operation unit 112, a code reader 113, a coin vendor 114, a service unit communication interface circuit 116, and a photo printer 200.
The service control unit 111 is composed of circuits centered around a processor, and communicates with the multifunction device 101, the service operation unit 112, the code reader 113, the coin vendor 114, the receipt printer 115, and the photo printer 200 to perform control related to services.

2, the service operation unit 112 is provided on the upper part of the service unit 110. The service operation unit 112 includes a display device such as a liquid crystal display device that provides information to the user, and an operation detection device such as a touch panel that receives operations from the user.
The code reader 113 is a known device that reads one-dimensional codes or two-dimensional codes related to the services to be provided. The service control unit 111 recognizes the signal of the code read by the code reader 113.

The service control unit 111 controls the coin vendor 114 to execute billing processing related to the services provided by the image forming system 100. Furthermore, the service control unit 111 controls a well-known receipt printer 115 to issue receipts related to the services provided. The service control unit 111 also cooperates with the multifunction device control unit 11 to provide services using the multifunction device 101, and cooperates with the photo printer control unit 201 to provide services using the photo printer 200.

The service unit communication interface circuit 116 is an interface circuit for communicating with the multifunction device 101 and external devices (not shown).
The photo printer 200 prints photographic images on photo paper and includes a photo printer control unit 201, a photo printer printing unit 204, and a photo printer data storage unit 205.

The photo printer control unit 201 is composed of circuits centered around a processor, and the processor executes a control program stored in the multifunction device data storage unit 15 to control each unit of the multifunction device 101. The photo printer control unit 201 cooperates with the service control unit 111 to provide services of the image forming system 100 using the photo printer 200.
The photo printer printing unit 204 is a dye-sublimation color printer engine. The configuration of the photo printer printing unit 204 will be described separately later.

The photo printer data storage unit 205 includes a non-volatile memory for storing the processing programs executed by the photo printer control unit 201, and a RAM for storing data.
The receipt and the photo image printed on the photo paper are discharged to the photo discharge port 150. The receipt is discharged to the receipt discharge port 151.
1 shows an embodiment in which there are three control units, the service control unit 111, the multifunction device control unit 11, and the photo printer control unit 201, which are mainly composed of a processor and a memory, but all or any two of these three control units may be integrated. In that case, the corresponding data storage units may also be integrated. That is, the multifunction device data storage unit 15 and the photo printer data storage unit 205 may be integrated.

<<Photo printer printing unit configuration>>
4 is an explanatory diagram showing the main parts of the photoprinter printing unit 204 according to this embodiment. The photoprinter printing unit 204 is a dye-sublimation printer, and is used with the ink ribbon R and roll paper P attached at predetermined positions.

The ink ribbon R is supplied from a supply reel 212, passes between a thermal head 214 and a platen roll 215, and is wound up on a take-up reel 211. The ink ribbon R is configured in a cassette format with the supply reel 212 and take-up reel 211 integrated together. The ink ribbon R has dye regions of Y, M, and C, for example, formed of sublimable dyes of the respective colors of yellow (Y), magenta (M), and cyan (C), and thermoplastic resin. It also has a protective layer region (overcoat layer region) formed of the same thermoplastic resin.

These Y, M, and C occupation areas and protective layer areas are repeatedly formed at regular intervals in the longitudinal direction, which is the payout direction of the supply reel 212. Then, one image is printed using a set of Y, M, and C dye areas and protective layer areas. The photoprinter control unit 201 drives the take-up reel 211 to take up the ink ribbon R. The ink ribbon R moves in one direction from the supply reel 212 to the take-up reel 211.

The photo printer control unit 201 also controls the driving of the upstream transport roll 216 and the downstream transport roll 217. It also controls the pressing and releasing of the platen roll 215 against the thermal head 214. The platen roll 215 is a driven roller that is disposed opposite the thermal head 214 and supports the roll paper P being transported.

The photoprinter control unit 201 controls the roll paper P to be unwound from the holder 213, passed between a thermal head 214 and a platen roll 215, printed an image on the roll paper P, and discharged by passing through a downstream transport roll 217. When printing, the photoprinter control unit 201 not only transports the roll paper P downstream, but also controls the roll paper P to be wound up upstream.
A cutter 218 for cutting the rolled paper P is provided behind the transport roll 217. The photo printer control unit 201 controls the cutter 218 to cut the rolled paper P at a predetermined position and output a printed sheet Pa.

The thermal head 214 has an array of multiple heating elements. The photo printer control unit 201 selectively energizes the multiple heating elements depending on the image to be printed and its gradation level. The photo printer control unit 201 controls the platen roll 215 to sandwich the ink ribbon R and the roll paper P between it and the thermal head 214, and selectively causes each heating element of the thermal head 214 to generate heat, transferring the ink of the ink ribbon R corresponding to the heating location and amount of heat onto the roll paper P.

In detail, the photoprinter control unit 201 first aligns the printing area of the roll paper P with the Y dye area of the ink ribbon R. Then, the platen roll 215 is pressed against the thermal head 214 to sandwich the roll paper P and the ink ribbon R, and printing is performed on the printing area of the roll paper P with the yellow ink of the ink ribbon R.
Next, the platen roll 215 is released to allow the transport rolls 216 and 217 to take up the printing area of the roll paper P upstream, and the printing area of the roll paper P is aligned with the M dye area of the ink ribbon R. Then, the platen roll 215 is pressed against the thermal head 214 to sandwich the roll paper P and the ink ribbon R, and printing is performed with the magenta ink of the ink ribbon R on the printing area of the roll paper P that has been printed with the yellow ink.

The platen roll 215 is then released to allow the transport rolls 216 and 217 to take up the roll paper P upstream, and align it with the C dye area of the ink ribbon R. Then, the platen roll 215 is pressed against the thermal head 214 to sandwich the roll paper P and the ink ribbon R, and printing is performed with the cyan ink of the ink ribbon R on the printing area of the roll paper P that has been printed with yellow and magenta.

Finally, the platen roll 215 is released to allow the transport rolls 216 and 217 to take up the roll paper P upstream and align it with the protective layer of the ink ribbon R. Then, the platen roll 215 is pressed against the thermal head 214 to sandwich the roll paper P and the ink ribbon R, and the protective layer of the ink ribbon R is transferred (overcoat) to the entire surface of the printing area of the roll paper P that has been printed in yellow, magenta, and cyan.

In this manner, the photoprinter control unit 201 shifts the relative positions of the surface of the roll paper P and the ink ribbon R by at least 4 degrees to bring them into close contact with each other, and selectively transfers the Y, M, and C dye areas to the roll paper P to form a color image. Then, the ink in the protective layer area is transferred to the entire surface of the formed color image to perform overcoating.
The configuration of the photoprinter printing unit has been described above.

<About uneven density caused by the Newton Ring phenomenon>
Let us now explain in more detail about the density unevenness caused by the Newton ring phenomenon that can occur when reading a reflective original with a smooth surface using a flatbed scanner.
Fig. 5 is an explanatory diagram showing a read image 37 read by irradiating light from below the platen glass 33 onto the original 31 placed on the platen glass 33 of the scanner unit 13 in this embodiment. The original 31 and the platen glass 33 are shown in horizontal cross section. In the example shown in Fig. 5, the original 31 is a photographic image printed by the photoprinter 200. That is, the original 31 has an image formed of YMC ink layers 31b on the surface of smooth photo paper 31a. Furthermore, a transparent protective layer 31c is formed so as to cover the surface of the YMC ink layer 31b.

5 shows a state in which a portion of the area of the document 31 that comes into contact with the platen glass 33 has been deformed and flattened because the protective layer 31c on the surface of the document 31 is soft. The flattened area is shown as a contact area 35. However, around the contact area 35, a small gap exists between the platen glass 33 and the surface of the protective layer 31c.
The platen glass 33 has a different refractive index from that of air and the protective layer 31c. At the boundary between media with different refractive indices, fixed-end reflection and free-end reflection occur. In Figure 5, B indicates the free-end reflection that occurs on the top surface of the platen glass, which has a higher refractive index than air, while A indicates the fixed-end reflection that occurs on the document surface.

In the contact area 35, the irradiated light when reading the document 31 is reflected specularly. The fixed end reflection and the free end reflection are in opposite phase to each other, so they are offset and the amount of reflected light is attenuated. Therefore, in the contact area 35, the density of the read image 37 obtained by reading the amount of reflected light becomes high, and a high density area 39 corresponding to the contact area 35 is generated.
On the other hand, in the periphery of the contact area 35, the fixed end reflection and the free end reflection cancel each other out only in the area where the distance of the gap between the upper end surface of the platen glass 33 and the original 31 is an integer multiple of the wavelength, but because the surface of the original 31 has minute irregularities and the irradiated light is not of a single wavelength, the phenomenon in which the fixed end reflection and the free end reflection cancel each other out in a specific area is unlikely to occur. Therefore, no high-density area 39 is generated in areas other than the contact area 35.
The above is a fundamental explanation of why uneven density and color can occur due to the Newton's ring phenomenon when a document with a smooth surface is read.

<Printing control of calibration test patterns>
A soft protective layer 31c is formed on the smooth surface of the photographic image document 31 printed on photo paper. As described above, when reading with the flatbed type scanner unit 13, unevenness in density and color may occur due to the Newton's ring phenomenon.
Nowadays, when digital cameras are widespread, it is not thought that there are many cases where the document to be read by the scanner unit 13 is a photographic image printed on photo paper. Even when scanning a photographic image printed on photo paper, it is possible to check for unevenness due to the Newton's ring phenomenon by previewing the image, and to rescan the image if necessary.

However, when a calibration test pattern is output from the photoprinter 200 and read by the scanner unit 13 to calibrate the photoprinter 200, the pattern is more susceptible to unevenness caused by the Newton ring phenomenon than when scanning a normal document for the following reasons.
First, the purpose of reading the test pattern is to calibrate the photoprinter 200, not to obtain an image. Therefore, an operator does not usually take the trouble to preview the read image.
Secondly, when performing calibration, the test pattern printed by the photoprinter 200 is usually read immediately by the scanner. Therefore, the protective layer 31c on the surface of the test pattern is almost undamaged and is smooth and soft.

If unevenness occurs in the scanned image of the calibration test pattern due to the Newton ring phenomenon (see, for example, FIG. 6), the effect of the unevenness will not be limited to the scanned image, but will affect all printed materials by the photoprinter 200 that reflect the results of the calibration.
From this perspective, when it comes to calibration test patterns, even more care must be taken to prevent unevenness in the read image caused by the Newton's ring phenomenon than when printing and reading an ordinary photographic image.

Therefore, in this embodiment, only when a test pattern is printed for calibrating the photoprinter 200, control is performed so that the protective layer 31c is not basically formed.
The protective layer 31c is formed in order to further improve the weather resistance of the YMC ink layer 31b. That is, the protective layer 31c prevents moisture and oil from penetrating into the YMC ink layer 31b from the surface, and prevents gas and ultraviolet rays from directly irradiating the YMC ink layer 31b. This prevents fading and discoloration of the dyes, which are the coloring materials of the YMC ink layer 31b. For example, it prevents fading due to hydrolysis of the dyes, discoloration and fading due to chemical changes, fading due to sublimation, and fading due to ultraviolet decomposition, allowing the ink to withstand long-term storage and also prevents dirt.

During calibration, the test pattern printed by the photoprinter 200 is usually read immediately by the scanner, so long-term storage stability is not important.
In addition, the protective layer 31c is designed to be as colorless and transparent as possible so that there is no optical difference depending on whether it is present or not. Therefore, it can be said that the presence or absence of the protective layer 31c of the test pattern has no effect on the calibration.
7A and 7B are explanatory diagrams showing a normal printout and a calibration test pattern, respectively, that the service control unit 111 causes the photo printer 200 to print in this embodiment.

7A, the normal printout 41 of the photoprinter 200 has an image printed on the surface of photopaper 41a with YMC ink layers 41b, and a protective layer 41c is formed on the YMC ink layers 41b to overcoat the YMC ink layers 41b. The normal printout 41 is printed by the above-described control of the photoprinter printing unit configuration.
In contrast, the calibration test pattern printout 43 has a test pattern printed on the surface of photo paper 43a with a YMC ink layer 43b as shown in FIG. 7B, but no protective layer is overcoated thereon.

When the service request received by the service operation unit 112 is for a normal printing service using the photo printer 200, the service control unit 111 instructs the photo printer control unit 201 of the photo printer 200 to print together with the data of the image to be printed.
The photo printer control unit 201, which has received the instruction from the service control unit 111, performs normal printing to form a protective layer 41c based on the added image data, as shown in FIG. 7A.

On the other hand, if the service request received by the service operation unit 112 is a request to print a test pattern related to the calibration of the photo printer 200, the service control unit 111 sends a calibration instruction to the photo printer control unit 201. Upon receiving the instruction from the service control unit 111, the photo printer control unit 201 prints a test pattern based on the test pattern data stored in the photo printer data storage unit 205, as shown in FIG. 7B. When printing a test pattern, the protective layer 41c is not formed.

In the example shown in FIG. 7B, the protective layer is not formed over the entire area of the photo paper 43a which is the printing medium, but it is sufficient to avoid forming a protective layer at least in the area where the test pattern is printed.
7A, in the case of an overcoat process in which a protective layer 41c is formed on a YMC ink layer 41b in a dye-sublimation printer, the formation of the protective layer 41c generally requires a larger amount of heat than the formation of the YMC ink layer 41b. Therefore, when forming the protective layer 41c, the transport speed of the photo paper 43a is slower than when forming the YMC ink layer 41b. Although it depends on the layout, it is possible to increase the printing speed by not performing the overcoat process on areas other than the test pattern portion.

Assume that the operator places the printed test pattern printout 43 at a predetermined position on the platen glass (not shown in FIG. 2) of the scanner unit 13 of the multifunction device 101, and performs a predetermined operation on the service operation unit 112. In response to the operation, the service control unit 111 instructs the multifunction device control unit 11 to read the test pattern printout 43 placed on the scanner unit 13, and provide a read value of a predetermined location corresponding to the test pattern.
In accordance with the instruction, the multifunction device control unit 11 reads the test pattern printout 43 set on the platen glass and provides read values of a predetermined portion corresponding to the test pattern. The service control unit 111 causes the photo printer control unit 201 to perform correction based on the provided read values so that the characteristics related to the color tone and gradation of the photo printer 200 approach the target.

(Embodiment 2)
The service control unit 111 does not form a protective layer when printing a test pattern on photo paper with an uneven printing surface, but may form a partial protective layer when printing a test pattern on photo paper with a smooth surface to give it a glossy finish. The unevenness formed on the printing surface is for example for matte finish.
8A is an explanatory diagram showing an example of a test pattern printout 45 in which a test pattern is printed with YMC ink layers 45b on the surface of photo paper 45a with projections and recesses formed thereon. By not forming a protective layer, the projections and recesses formed on the surface of photo paper 45a are left as they are.

When the test pattern printout 45 shown in Figure 8A is placed on the platen of the scanner unit 13, the unevenness of the photo paper 75a left on the surface ensures a gap between it and the platen glass, making it less likely for unevenness due to the Newton's ring phenomenon to occur.
8B is an explanatory diagram showing an example of a test pattern printout 47 in which a test pattern is printed with YMC ink layers 47b on the surface 47a of photo paper that has been finished to be smooth to give it a glossy finish. In the example shown in FIG. 8B, a plurality of local protective layers 47c are formed by intermittently changing the power supply to the heating elements of the thermal head 214 depending on the location, and the protective layer 47c has an uneven surface. The test pattern printout 47 shown in FIG. 8B shows a cross section of the photo paper 47a, but the formed protective layer 47c may be a striped protective layer 47c arranged in the depth direction, or a checkered protective layer 47c may be formed.

Furthermore, in the example shown in Figure 8B, there are some areas where protective layer 47c is formed thickly and some areas where it is formed thinly, but it is also possible to form protective layer 47c locally and arrange areas where the protective layer is formed and areas where it is not formed, thereby forming unevenness on the surface of protective layer 47c.
8B is placed on the platen of the scanner unit 13, the unevenness of the protective layer 47c ensures a gap between the platen glass and the test pattern printout 47. Even if the photo paper 47a has a smooth surface, unevenness due to the Newton's ring phenomenon is unlikely to occur.
In the example shown in FIG. 8B, the protective layer 47c having projections and recesses is formed over the entire area of the photo paper 43a, which is the printing medium. However, it is sufficient to form the protective layer having projections and recesses at least in the area where the test pattern is printed.

(Embodiment 3)
In this embodiment, when a calibration test pattern is read by the scanner unit 13, if there is a high density area 39 due to partial unevenness caused by the Newton's ring phenomenon as shown in Fig. 6, for example, calibration is performed without using the read value corresponding to the high density area 39. The test pattern is normally a pattern made up of gradation patches of each color Y, M, and C corresponding to the ink ribbon R. The read values corresponding to the gradation patches should be arranged in order of density of the gradation patches, but if a high density area 39 exists somewhere, the read value may be reversed with respect to an adjacent density patch, or even if there is no reversal, the density difference may become an unnatural value.

If an unnatural difference appears in a patch area that should have a uniform density, it can be determined that a part of the patch area contains a high density area 39. Therefore, it is sufficient to use only the readings of the part determined to be outside the high density area 39.
When all patch areas of a certain density belong to the high density area 39, the relationship with the read values of adjacent patches becomes unnatural as described above, so it can be determined that there is a high density area 39. In that case, the patch areas belonging to the high density area 39 may not be adopted, and may be complemented with the read values of adjacent patches.

(Embodiment 4)
In the first embodiment, a configuration as a printing system has been described; that is, as shown in FIG. 1, the system is provided with a multifunction device 101 and a service unit 110. In the first embodiment, as shown in FIG.
In a different embodiment, the photo printer and the scanner may be configured as a single device, that is, as a multifunction device.
The photo printer has the same function as the photo printer printing unit 204 shown in Fig. 1. The scanner has the same function as the scanner unit 13 shown in Fig. 1. The control unit that controls them corresponds to an integration of the service control unit 111, photo printer control unit 201, and multifunction device control unit 11 shown in Fig. 1.

As mentioned above,
(i) A printing system according to the present invention comprises a printing device and an image reading device, the printing device comprising a printing unit which forms a pattern using an ink layer on the surface of a printing medium and forms a transparent protective layer on the formed ink layer, and a control unit which uses the printing unit to form a test pattern and an image pattern for calibration, the image reading device comprising an image reading unit which optically reads the formed test pattern, the control unit controlling, when forming the image pattern, to form a protective layer covering the image pattern, and when forming the test pattern, to either not form a protective layer at least in the area where the test pattern is formed, or to form a protective layer which is more non-uniform than the protective layer covering the image pattern, at least in the area where the test pattern is formed.

The print medium is a medium on whose surface printing is performed. A specific example of the print medium is printing paper. The roll paper and photo paper in the above-mentioned embodiments correspond to the print medium of this invention.
The image reading unit is a unit for reading an image of a document. A specific example of the image reading unit is a scanner. The scanner unit in the above-described embodiment corresponds to the image reading unit of the present invention.
Furthermore, the control unit is mainly composed of a processor, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and a memory. The control unit reads out a control program pre-stored in the memory and executes processing.

The photo printer in the above embodiment corresponds to the printing device of the present invention, and the multifunction device corresponds to the image reading device of the present invention. The service control unit in the above embodiment corresponds to the control unit of the present invention. However, the service control unit, photo printer control unit, and multifunction device control unit work together to perform processing, and in a different aspect, at least a part of the photo printer control unit and/or multifunction device control unit may further correspond to the control unit. Also, there may be an aspect in which at least one of the service control unit, photo printer control unit, and multifunction device control unit is integrated, and the integrated aspect may correspond to the control unit of the present invention.

Further, preferred embodiments of the present invention will be described.
(ii) The printing medium may have projections and recesses formed on a printing surface, and the control unit may perform control so as not to form a protective layer when the test pattern is formed.
In this way, when forming a test pattern, the protective layer is not formed, leaving the surface irregularities formed on the printing medium, and the remaining irregularities can suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

(iii) The printing medium is smoothed to give it a glossy finish, and the control unit may control the printing medium to form a uniform protective layer when forming the image pattern, and to form a partial protective layer when forming the test pattern, or to form a non-uniform protective layer having layers of different thicknesses in some parts.
In this way, even with a smoothed printing medium, a partial protective layer can be formed, or an uneven protective layer having layers of different thicknesses arranged in parts can be formed to give the protective layer unevenness, and the unevenness of the protective layer can be used to suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

(iv) If the control unit determines that there is uneven density in an area of the test pattern read by the image reading unit that should be a pattern of uniform density, it may perform calibration without using the reading values of the areas with high unevenness.
In this way, even if Newton's rings cause dark uneven areas in areas that should be uniformly dense, these areas can be excluded from the readings, thereby reducing the effect of Newton's rings on the calibration results.

(v) One aspect of the invention includes a printing device that includes a printing unit that forms a pattern on the surface of a printing medium using an ink layer and forms a transparent protective layer on the formed ink layer, a control unit that uses the printing unit to form a test pattern and an image pattern for calibration, and an image reading unit that optically reads the formed test pattern, and the control unit controls the printing device to form a protective layer that covers the image pattern when the image pattern is formed, and to not form a protective layer at least in the area where the test pattern is formed, or to form a protective layer that is less uniform than the protective layer that covers the image pattern, at least in the area where the test pattern is formed.

(vi) The printing medium may have projections and recesses formed on a printing surface, and the control unit may perform control so as not to form a protective layer when the test pattern is formed.
In this way, when forming a test pattern, the protective layer is not formed, leaving the surface irregularities formed on the printing medium, and the remaining irregularities can suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

(vii) The printing medium is smoothed to give it a glossy finish, and the control unit may control the printing medium to form a uniform protective layer when forming the image pattern, and to form a partial protective layer when forming the test pattern, or to form a non-uniform protective layer having layers of different thicknesses in some parts.
In this way, even with a smoothed printing medium, a partial protective layer can be formed, or an uneven protective layer having layers of different thicknesses arranged in parts can be formed to give the protective layer unevenness, and the unevenness of the protective layer can be used to suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

(viii) One aspect of the present invention includes a method of printing a test pattern, comprising the steps of a control unit of a printing device that forms a test pattern and an image pattern for calibration, forming a pattern of an ink layer on the surface of a printing medium using a printing unit, forming a transparent protective layer on the formed ink layer, and optically reading the formed test pattern using an image reading unit, and the control unit controls the control unit to form a protective layer that covers the image pattern when the image pattern is formed, and to not form a protective layer at least in the area where the test pattern is formed, or to form a protective layer that is less uniform than the protective layer that covers the image pattern, at least in the area where the test pattern is formed.

(ix) The method may further include a step of accepting a selection of whether the printing surface of the printing medium is smooth or has an uneven surface, and the control unit may control so as not to form a protective layer when forming the test pattern on a printing medium having an uneven surface.
In this way, when forming a test pattern, the protective layer is not formed, leaving the surface irregularities formed on the printing medium, and the remaining irregularities can suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

(x) The method may further include a step of accepting a selection of whether the printing surface of the printing medium is smooth or has an uneven surface, and the control unit may control the printing medium to form a uniform protective layer when forming the image pattern on a printing medium with a smooth printing surface, and to form a partial protective layer when forming the test pattern, or to form an uneven protective layer having layers of different thicknesses in some parts.
In this way, even with a smoothed printing medium, a partial protective layer can be formed, or an uneven protective layer having layers of different thicknesses arranged in parts can be formed to give the protective layer unevenness, and the unevenness of the protective layer can be used to suppress density unevenness in the reading results caused by the Newton's ring phenomenon.

The aspects of the present invention include any combination of the above-mentioned aspects.
In addition to the above-mentioned embodiment, various modifications of the present invention are possible. These modifications should not be interpreted as not falling within the scope of the present invention. The present invention should include all modifications within the scope of the claims and the equivalent meanings.

11: Multifunction device control unit, 12: Multifunction device operation unit, 13: Scanner unit, 14: Multifunction device print unit, 15: Multifunction device data storage unit, 16: Multifunction device communication interface circuit, 20: Light source, 21: First scanning unit, 22: Second scanning unit, 23: Imaging lens, 24: Line image sensor, 31: Original, 31a, 41a, 43a, 45a, 47a: Photo paper, 31b, 41b, 43b, 45b, 47b: YMC ink layers, 31c, 41c, 47c: Protective layer, 33: Platen glass, 35: Contact area, 37: Read image, 39: High density area, 41: Normal print output, 43, 45, 47: Test pattern print output, 100: Image forming system, 101: Multifunction device, 110: Service unit, 111: Service control unit, 112: Service operation unit, 113: Code reader, 114: Coin vendor, 115: Receipt printer, 116: Service unit communication interface circuit, 150: Photo outlet, 151: Receipt outlet 200: Photo printer, 201: Photo printer control unit, 204: Photo printer printing unit, 205: Photo printer data storage unit, 211: Take-up reel, 212: Supply reel, 213: Holder, 214: Thermal head, 215: Platen roll, 216, 217: Transport rolls, 218: Cutter P: Roll paper, Pa: Cut sheet, R: Ink ribbon

Claims (10)

Equipped with a printing device and an image reading device,
The printing device includes:
a printing unit for forming a pattern on a surface of a printing medium using an ink layer and forming a transparent protective layer on the formed ink layer;
a control unit for forming a test pattern and an image pattern for calibration by using the printing unit;
The image reading device includes:
an image reading unit for optically reading the formed test pattern;
The control unit controls the printing system so that, when forming the image pattern, a protective layer covering the image pattern is formed, and, when forming the test pattern, either not to form a protective layer in at least the area in which the test pattern is formed, or to form a protective layer that is more non-uniform than the protective layer covering the image pattern in at least the area in which the test pattern is formed. The printing medium has a printing surface having projections and recesses,
The printing system according to claim 1 , wherein the control unit performs control so as not to form a protective layer when the test pattern is formed. The print medium is smoothed to give it a glossy appearance;
The printing system according to claim 1 , wherein the control unit controls to form a uniform protective layer when forming the image pattern, and to form a partial protective layer when forming the test pattern, or to form a non-uniform protective layer having layers of partially different thicknesses arranged side by side. The printing system of claim 1, wherein when the control unit determines that there are unevenness in density or color in an area of the test pattern read by the image reading unit that should be a pattern of uniform density, the control unit performs calibration without using the reading value of the part with the dark unevenness. a printing unit for forming a pattern on a surface of a printing medium using an ink layer and forming a transparent protective layer on the formed ink layer;
a control unit for forming a test pattern and an image pattern for calibration by using the printing unit;
The control unit controls the printing device to form a protective layer covering the image pattern when forming the image pattern, and to form no protective layer in at least the area where the test pattern is formed, or to form a protective layer that is more non-uniform than the protective layer covering the image pattern in at least the area where the test pattern is formed, when forming the test pattern. The printing medium has a printing surface having projections and recesses,
The printing apparatus according to claim 5 , wherein the control unit performs control such that a protective layer is not formed when the test pattern is formed. The print medium is smoothed to give it a glossy appearance;
The printing device according to claim 5, wherein the control unit controls to form a uniform protective layer when forming the image pattern, and to form a partial protective layer when forming the test pattern, or to form a non-uniform protective layer in which layers of different thicknesses are arranged in parts. A control unit of a printing device that forms a test pattern and an image pattern for calibration,
forming a pattern on a surface of a print medium using a printing unit;
forming a transparent protective layer on the formed ink layer;
and optically reading the formed test pattern using an image reading unit;
The control unit controls, when forming the image pattern, to form a protective layer covering the image pattern, and, when forming the test pattern, to either not form a protective layer in at least the area in which the test pattern is formed, or to form a protective layer that is more non-uniform than the protective layer covering the image pattern in at least the area in which the test pattern is formed. The method further includes a step of accepting a selection of whether the printing surface of the printing medium is smooth or has a textured surface,
The printing method according to claim 8 , wherein the control unit performs control so as not to form a protective layer when the test pattern is formed on a printing medium having an uneven printing surface. The method further includes a step of accepting a selection of whether the printing surface of the printing medium is smooth or has a textured surface,
The printing method according to claim 8, wherein the control unit controls to form a uniform protective layer when forming the image pattern on a printing medium having a smoothed printing surface, and to form a partial protective layer when forming the test pattern, or to form an uneven protective layer in which layers of different thicknesses are arranged in parts.