JP5387438B2 - Gloss evaluation apparatus and gloss evaluation method - Google Patents

Description

  The present invention relates to a gloss evaluation apparatus and a gloss evaluation method that express glossiness of an entire image in which regions having different toner amounts are mixed.

In full-color copying machines and full-color printers that use electrophotographic processes, toner images of multiple colors (usually four colors of cyan, magenta, yellow, and black) are arranged on a recording medium (paper), and this toner image Is fixed on the recording medium by heating and pressing in a fixing device.
As an example of the fixing device, one constituted by a pair of rollers called a heating roller and a pressure roller has been proposed. A heating source such as a halogen lamp is disposed inside the heating roller. Then, by passing a sheet on which a toner image is formed between the pair of fixing rollers, the color toner is thermally melted and fixed on the recording medium.
As another configuration of the fixing device, a fixing belt in which a release layer such as a fluororesin is formed on the surface of an elastic layer such as silicon rubber is stretched over a plurality of stretching rolls, and a pair of tensioning belts are sandwiched between the fixing belts. The gantry roll and the pressure roll are arranged opposite to each other, and a heating source such as a halogen lamp is built in the gantry roll. By passing a recording medium (paper) on which a toner image is formed between the fixing belt and the pressure roller, the color toner is thermally melted and fixed on the paper. This fixing belt system has advantages such as low-temperature fixing (energy saving) and improved separability because the fixing nip can be set freely by adopting a belt configuration.

The color toner has an average particle size of 5 to 1 to 10 μm particles containing a thermoplastic resin such as polyester resin, styrene / acrylic copolymer, styrene / butadiene copolymer as a main component and a colorant dispersed therein. Fine particles of about ˜100 nm, for example, inorganic fine particles such as silicon oxide, titanium oxide and aluminum oxide are externally added.
As a toner colorant, Y (yellow) is benzidine yellow, quinoline yellow, banzai yellow, etc. M (magenta) is rhodamine B, rose bengal, pigment red, etc. C (cyan) is phthalocyanine blue K (black) such as aniline blue and pigment blue are carbon black and aniline black.
In addition, so-called oil-less toner, in which oil is not applied to the heating roller during fixing by enclosing WAX in the toner, is also widely used.

In addition, in recent years, surface irregularities such as plain paper, which has been widely used in the past, are large, and in addition to recording media with low gloss, surface irregularities such as art paper, coated paper, fine coated paper are small, There is an increasing demand to output high-quality images by applying it to recording media with high glossiness. Art paper, coated paper, and the like are generally produced by applying a coating layer such as resin on the surface of the paper, so that the so-called glossiness is generally higher than that of plain paper. However, in recent years, coated paper (matte coated paper) having a glossiness as small as that of plain paper has been used for the purpose of giving a paper document a high-class feeling. For this reason, there is a demand for stable output of high-quality images for a wide variety of recording media.
With such a background, it has been demanded to further improve the image quality such as “glossiness (surface quality)” of the toner image formed on the recording medium. Along with this, an evaluation device and an evaluation method for evaluating the “glossiness” of the toner image are required.

  As a conventional technique for evaluating “glossiness”, Patent Document 1 outputs image data to which gloss information and texture information are added using information of diffuse reflection light in addition to regular reflection light. Technology is disclosed. This technology includes means for generating an image signal generated by receiving diffusely reflected light, gloss information generated by a predetermined method, and texture information generated by a predetermined method separately from this, Image data generating means for generating image data representing an object to be picked up based on the image signal, and output means for adding the gloss information and the texture information to the image data generated by the image data generating means and outputting the image data It is characterized by providing. Here, there is no way to read the information about the unevenness of the object to be imaged, and for this reason, the conventional technology could not provide a mechanism that can sufficiently read the information about the texture and reproduce it. For this reason, it is disclosed that the above-described configuration can satisfactorily read and reproduce information related to the texture from the object to be imaged.

  Patent Document 2 discloses a technique in which a glossiness evaluation value having a high correlation with subjective glossiness can be obtained by deriving a glossiness evaluation value based on the variable angle reflected light angle distribution. ing. The present invention is a gloss evaluation device that generates an evaluation value related to the gloss of an object surface, and includes a variable reflection light distribution characteristic acquisition unit and an evaluation parameter extraction unit that extracts an evaluation parameter from the acquired variable reflection light distribution characteristic And glossiness evaluation value calculation means for calculating a glossiness evaluation value based on the extracted evaluation parameter. This technique has a problem that the measurement values obtained from conventional gloss meters, haze meters, and image clarity measuring devices do not correspond to human visual evaluation, and physical elements sufficient for glossiness evaluation are measured. Although not described, it is disclosed that a glossiness evaluation apparatus capable of obtaining a glossiness evaluation value having a high correlation with subjective glossiness can be provided by using the above-described configuration.

Further, Japanese Patent Laid-Open No. 2004-228561 discloses a technique with the content of detecting the gloss of an image accurately by improving the detection system of specular reflection light by switching the wavelength of reflected light.
In this technique, in the reflected light detection device that detects the amount of specularly reflected light, the light receiving means is configured to receive specularly reflected light having the smallest amount of diffusely reflected light that propagates in the same direction as the specularly reflected light. In the conventional configuration, the light receiving means for receiving the light in the regular reflection direction detects not only the regular reflection light but also the diffuse reflection light diffused in the regular reflection direction. As a result, the regular reflection light cannot be accurately detected from the amount of light received by the light receiving means, and the gloss of the detection target cannot be accurately detected. Since the specular reflection light can be accurately detected, the gloss of the detection target can be accurately detected.

As described above, in recent years, it has been required to perform optimum image formation on a wide variety of sheets having a high glossiness from a paper having a low glossiness. In other words, there is a strong demand to output an image in a state where the “glossiness” is the same in all image areas including the paper portion and the image portion. On the other hand, in the output image, various colors are expressed by switching the amount of toner arranged on the paper. In other words, the output image includes a mixture of regions having different toner amounts. For this reason, in order to make the “glossiness” uniform in the entire image, not only the “glossiness” of the paper portion and the image portion are matched, but also in all the image areas where various toner amounts are arranged. It is necessary to match the “glossiness”.
For evaluation and quantification of image gloss, so-called “glossiness (60 degree glossiness: G60)” has been generally used. Conventionally, regarding gloss, it has been considered that if the glossiness of the paper and the glossiness of the image portion can be set to coincide with each other, it is possible to obtain an image with a preferable glossiness. However, according to the study conducted by the inventor, even if the glossiness of the paper and the image portion is the same, the “glossiness” does not necessarily match, and even if the glossiness of the paper and the image portion is the same, the glossiness is rather different. It became clear that a sense of incongruity may occur.

As described above, the reason why the “glossiness” does not always match even when the glossiness is matched can be described as follows. There is a difference in the material constituting the surface between the paper and the toner image, and a physical difference between the materials includes a difference in refractive index. For this reason, the reflected light beam on the surface (total light beam reflected on the surface) is different. Since the relationship between the reflectance and the refractive index follows the so-called Fresnel equation, the reflected light beam on the surface increases as the refractive index increases.
Since the refractive index of the paper and the refractive index of the toner are expected to be about 1.4 (paper) and 1.6 (toner), respectively, when the Fresnel formula is applied assuming that the target is a mirror surface The reflectances are 0.028 (paper) and 0.053 (toner), respectively, and the reflected light flux on the surface of the paper and toner is large.
In many cases, the surface of the paper has a structure in which a porous (small hole) is opened even in coated paper. On the other hand, the surface of the toner image does not have such a porous structure and has a closely packed structure. That is, the surface structure is fundamentally different between the paper and the toner image. It is expected that the difference in the porous structure may cause the phenomenon described above because the reflected light beam on the surface is different. As described above, it is considered that the reflected light flux characteristics are greatly different between the paper and the toner image.

Further, the measured value of the so-called “glossiness” (60-degree glossiness: G60) is defined in a specified area (4.4 in terms of the light receiving opening angle) in the vicinity of the 60-degree regular reflection position as specified in JIS Z8741. Calculated from the luminous flux at (within degrees).
That is, if the luminous flux that falls within this light receiving opening angle is the same, the measured value of the glossiness is the same. For this reason, even if the glossiness is the same value, it cannot be said that even the surface reflection characteristics match. When the glossiness (G60) based on this measurement principle is applied to measurement objects with different reflected light fluxes, such as the above-mentioned paper and toner image, the “glossiness” is the same even if the glossiness is simply matched. It is thought not to.

Such a problem that “glossiness” does not always match even when glossiness is simply matched is considered to occur even in gloss characteristic values other than 60 ° glossiness (G60). This is because the measurement principle of the gloss characteristic value has a measurement principle very similar to the measurement principle of the 60 degree glossiness. More specifically, 20 degree specular gloss, 45 degree specular gloss, 75 degree specular gloss, 85 degree specular gloss, and other gloss levels are similar in measurement principle to the 60 degree gloss level, and the same problem may occur. Is big. For this reason, even if a gloss characteristic value other than 60 degree glossiness is used, it does not lead to the solution of the above problem.
For this reason, the problem that “glossiness” does not always match even if gloss characteristic values (such as G60) are simply matched is a problem caused by the difference in surface reflection characteristics between the paper and the toner image. Can be considered. This problem is particularly serious when trying to evaluate the “glossiness” of the entire image in which various toner amounts are arranged on the paper. This is because “glossiness” does not always match even if the gloss characteristic value is considered to be the same for the entire image, based on the gloss characteristic value.

In the cited documents 1 to 3 aiming at improving the “glossiness” of the image, there are the following problems, respectively, and further problem solving is necessary.
Patent Document 1 is configured to output image data with gloss information and texture information using information of diffusely reflected light in addition to specularly reflected light. However, since the purpose is to generate image data with gloss information (texture information) added, there is a description of a method for calculating gloss information in each area of the image area, but “glossiness” as the whole image is described. There is no disclosure of a technique for evaluating whether or not they match.
In Patent Document 2, the glossiness evaluation apparatus derives a glossiness evaluation value based on the variable angle reflected light angle distribution, thereby obtaining a glossiness evaluation value highly correlated with subjective glossiness. . However, although the glossiness of one image pattern (one patch) can be specified, there is no disclosure of a technique for evaluating whether or not the “glossiness” of the entire image matches.
In Patent Document 3, the glossiness evaluation value is derived using the variable reflection light angle distribution, and “the glossiness of the paper and the toner image portion does not match even if the glossiness is matched”. It raises problems. However, regarding the actual evaluation value calculation, the explanation is conceptual and almost no specific explanation is given. For this reason, if the evaluation value is the same even if there is a difference between the paper and the toner image portion, it is completely unknown whether the “glossiness” is the same.

  In addition, the measurement of the variable reflection light angle distribution is a complicated measurement compared with the measurement of the glossiness (G60). Therefore, the evaluation value is derived for one image pattern, and the “glossiness” In the case where an evaluation value is derived after measuring many image patterns with a focus on "", the complexity of the measurement is considered to be a bottleneck. For this reason, a method of evaluating the “glossiness” by a simpler method is desirable, and the cited documents 1 to 3 consider that a problem remains in terms of measurement complexity. For example, the reflected light detection device of Patent Document 1 is also considered to be a technique that contributes to the purpose of specifying the gloss of one image pattern (one patch), but the “glossiness” as a whole also matches. There is no disclosure of technology that evaluates whether or not the

  Therefore, the present invention has been made in view of the above problems, and the problem is to express that “glossiness” is consistent with the entire image in which regions having different toner amounts are mixed. A gloss evaluation apparatus and a gloss evaluation method are proposed. As another problem, a gloss evaluation device that can express that the “glossiness” matches by the same measurement as a general-purpose measuring instrument such as glossiness (G60) without requiring a special measuring / measuring instrument. And a gloss evaluation method.

The features of the present invention, which is a means for solving the above problems, are listed below.
The gloss evaluation apparatus of the present invention is a gloss evaluation apparatus for evaluating the glossiness of a toner image formed on a recording medium, and is a gloss for characteristic values corresponding to a plurality of toner adhesion amounts (hereinafter abbreviated adhesion characteristic values). The glossiness is evaluated based on the difference between the ideal relationship determined in advance by two straight lines and the actual measurement data obtained by measurement from the relationship with the characteristic value related to Characteristic gloss evaluation device.
Further, the gloss evaluation apparatus of the present invention is further characterized in that the ideal relationship predetermined by the two straight lines is determined by locations corresponding to the following three toner adhesion states.
(A) Paper (state in which toner is not adhered) location (B) Secondary color solid location (C) Maximum density location Further, the gloss evaluation device of the present invention further includes: Gloss characteristic values in (B) secondary color solid portion "and" (C) highest density portion "are the same.
Further, the gloss evaluation apparatus of the present invention further sets the difference between the measured data and the ideal relationship as the difference in the gloss characteristic value with respect to the same value of the adhesion amount characteristic value, which is ΔGi (subscript i indicates a plurality of measured data). The gloss evaluation value E is evaluated by the following equation, where ΔGmax is the maximum value and ΔGmin is the minimum value for the subscript i of ΔGi.
When ΔGmax and ΔGmin have different signs, E = | ΔGmax | + | ΔGmin |
When ΔGmax and ΔGmin have the same sign, E = max (| ΔGmax |, | ΔGmin |)
Further, the gloss evaluation apparatus of the present invention further sets the adhesion amount characteristic value to “lightness: L ^* ” (lightness L ^* in CIELAB color space), and sets the gloss characteristic value to “60 degree glossiness: G60” (JISZ8741). 60 degree specular gloss).
Further, the gloss evaluation apparatus of the present invention further includes “(A) paper (the state where no toner is attached) among the three toner attached states that determine a function determined by two straight lines defined as an ideal relationship. Gp is Gp and the gloss characteristic value (glossiness G60) at “(B) secondary color solid portion” is Gr, Gr = 0. The 6 × Gp + 21 relationship is established.
Further, the gloss evaluation apparatus of the present invention further includes “(A) paper (the state where no toner is attached) among the three toner attached states that determine a function determined by two straight lines defined as an ideal relationship. Gd = 0.6 ×, where Gp is the value of the gloss characteristic value (glossiness G60) at “G” and Gd is the value of the gloss characteristic value (glossiness G60) at “(C) highest density location”. It is characterized in that the relationship of Gp + 21 is established.

The gloss evaluation method of the present invention is a gloss evaluation method for evaluating the glossiness of a toner image formed on a recording medium, and is a gloss for characteristic values corresponding to a plurality of toner adhesion amounts (hereinafter abbreviated adhesion characteristic values). The glossiness is evaluated based on the difference between the ideal relationship determined in advance by two straight lines and the actual measurement data obtained by measurement from the relationship with the characteristic value related to Features.
The gloss evaluation method of the present invention is further characterized in that the ideal relationship determined in advance by the two straight lines is determined by locations corresponding to the following three toner adhesion states.
(A) Paper (state in which toner is not adhered) location (B) Solid secondary color location (C) Maximum density location Further, the gloss evaluation method of the present invention further includes: Gloss characteristic values in (B) secondary color solid portion "and" (C) highest density portion "are the same.
In the gloss evaluation method of the present invention, furthermore, the difference between the measured data and the ideal relationship is defined as the difference in the gloss characteristic value with respect to the same value of the adhesion amount characteristic value, which is expressed as ΔGi (subscript i indicates a plurality of measured data). The gloss evaluation value E is evaluated by the following equation, where ΔGmax is the maximum value and ΔGmin is the minimum value for the subscript i of ΔGi.
When ΔGmax and ΔGmin have different signs, E = | ΔGmax | + | ΔGmin |
When ΔGmax and ΔGmin have the same sign, E = max (| ΔGmax |, | ΔGmin |)
Further, in the gloss evaluation method of the present invention, the adhesion amount characteristic value is “lightness: L ^* ” (lightness L ^* ) in CIELAB color space, and the gloss characteristic value is “60 degree glossiness: G60” (JISZ8741). 60 degree specular gloss).
In addition, the gloss evaluation method of the present invention further includes “(A) paper (the state in which no toner is attached) among the three toner attached states that determine a function determined by two straight lines defined as an ideal relationship. Gp is Gp and the gloss characteristic value (glossiness G60) at “(B) secondary color solid portion” is Gr, Gr = 0. The relationship of 6 × Gp + 21 is established.
In addition, the gloss evaluation method of the present invention further includes “(A) paper (the state in which no toner is attached) among the three toner attached states that determine a function determined by two straight lines defined as an ideal relationship. Gd = 0.6 ×, where Gp is the value of the gloss characteristic value (glossiness G60) at “G” and Gd is the value of the gloss characteristic value (glossiness G60) at “(C) highest density location”. It is characterized in that the relationship of Gp + 21 is established.
A program according to the present invention causes a computer to execute any one of the gloss evaluation methods described above.
The storage medium of the present invention is characterized in that the program is stored on a memory.

The present invention, which is a means for solving the above problems, has the following specific effects.
In the gloss evaluation apparatus of the present invention, as a relationship between the gloss characteristic value and the adhesion amount characteristic value, a function determined by two straight lines is defined as an ideal relationship, and measured data obtained by measuring this ideal relationship and an actual evaluation object Therefore, it is possible to provide a gloss evaluation apparatus that evaluates the evaluation value of the glossiness to be evaluated based on the difference between the glossiness and the evaluation target.
Further, in the gloss evaluation method of the present invention, as a relationship between the gloss characteristic value and the adhesion amount characteristic value, a function determined by two straight lines is defined as an ideal relationship, and this ideal relationship and an actual evaluation object are measured. Based on the difference from the actual measurement data, the evaluation value of the glossiness to be evaluated can be provided.
Further, the program of the present invention can provide a program capable of evaluating the uniformity of “glossiness” by executing the gloss evaluation method on a computer.
Further, the recording medium of the present invention is a storage medium in which a program is stored in a memory, and the uniformity of “glossiness” can be evaluated by causing the computer to execute the program stored in the storage medium. A recording medium that can be provided can be provided.

It is a figure which shows the structure of the glossiness evaluation apparatus of this invention. It is a figure for demonstrating the ideal relationship of adhesion amount characteristic value and glossiness characteristic value by evaluation by this invention. It is a figure which shows the patch of the image of the measuring object evaluated by this invention. It is a figure for demonstrating evaluation by this invention. It is a figure which shows the relationship between the measured value of the brightness L ^* by the image forming conditions, and the measured value of G60. It is a figure which shows the relationship between the measured value of the brightness L ^* by the image forming conditions, and the measured value of G60. It is a figure which shows the relationship between the measured value of the brightness L ^* by the image forming conditions, and the measured value of G60. It is a figure which shows the relationship between the measured value of the brightness L ^* by the image forming conditions, and the measured value of G60. It is a figure which shows the relationship between the measured value of the brightness L ^* by the image forming conditions, and the measured value of G60. It is a figure which shows the patch of the image of the measuring object of the other example evaluated by this invention. It is a figure for demonstrating evaluation by this invention. It is a block diagram explaining the glossiness evaluation method of the present invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is a diagram showing the configuration of the gloss evaluation apparatus of the present invention.
The gloss evaluation device 40 of the present invention measures a plurality of patches with different images to be measured, and collects the value of the lightness L ^* , which is a toner adhesion amount characteristic value, and a gloss characteristic value of 60. G60 measuring device 30 that collects the value of glossiness (G60), and gloss evaluation device 40 that generates an evaluation value related to “glossiness” of the entire image from each value of lightness L ^* and G60. .
The lightness measuring device 20 measures the target patch and measures the lightness L ^* in the CIELAB color space. The color measurement method and the lightness L ^* value calculation method in the lightness measuring device 20 are realized by the methods defined in JISZ8722, JISZ8701, and JISZ8729. In addition, since a measuring device compliant with these standards is manufactured by a color measuring device manufacturer, such a measuring device can be used as the brightness measuring device 20.
The G60 measuring device 30 measures the target patch and measures 60 degree glossiness (G60). The color measurement method and the G60 value calculation method in the G60 measuring device 30 are realized by the methods defined in JISZ8741. Similar to the lightness measuring device 20, a glossiness measuring device compliant with such a standard is manufactured by a glossometer manufacturer, and thus such a glossiness measuring device can be used as the lightness measuring device 20.

In the present invention, due to the difference in surface reflection characteristics between the paper and the toner image portion, even when the paper and the toner image show the same G60 value, the “glossiness” is not always the same. Absent.
Further, the image to be evaluated represents various colors by switching the amount of toner arranged on the paper. At this time, when the state of the toner arranged on the sheet is viewed from the viewpoint of the surface state of the image, it can be roughly classified into the following two states.
(1) The surface of the image is in a state where the toner amount increases or decreases in a state where the paper portion and the toner image portion are mixed.
(2) A state in which the amount of toner increases or decreases while the surface of the image is completely covered with toner.

Examples of the state (1) include an intermediate level (density) primary color, an intermediate level secondary color, an intermediate level tertiary color, and the like.
As an example of the state (2), a color in which the second color is superimposed on the first solid color, a color in which the third color is superimposed on the secondary color solid, and the like can be given.
It is desirable to set different gloss measurement values (G60) for the paper and the image area. For this reason, in the case of state (1) (a state in which the toner amount increases or decreases when the paper portion and the toner image portion coexist), the ratio between the paper portion and the toner image portion on the paper is made to correspond. By setting the gloss measurement value (G60) that varies depending on the shape, the gloss characteristic value (G60) reflecting a desirable “glossiness” can be obtained even in the state (1).
In the case of state (2) (the amount of toner increases or decreases when the surface of the image is completely covered with toner), the entire surface of the image is covered with toner even if the amount of toner increases or decreases. Therefore, since the reflection characteristics of the image surface do not change, the same gloss characteristic value (G60) may be set in order to make the “glossiness” the same.
However, since the gloss characteristic value such as G60 includes reflected light from the inside of the paper in addition to the reflected light from the image surface, in order to remove the influence of the reflected light from the inside of the paper, the toner amount is increased or decreased. A gloss characteristic value (G60) that changes accordingly may be set.

FIG. 2 is an illustration for explaining an ideal relationship between the adhesion amount characteristic value and the gloss characteristic value in the evaluation according to the present invention. In this figure, the horizontal axis represents the adhesion amount characteristic value (lightness L ^* ), and the vertical axis represents the gloss characteristic value (G60).
The area shown in (1) of FIG. 2 corresponds to the state (1), and shows a state where the toner amount increases or decreases in a state where the paper portion and the toner image portion are mixed.
A region indicated by (2) in the figure corresponds to the state (2), and shows a state in which the toner amount increases or decreases when the toner is completely covered with the toner.
The relationship represented by the line in FIG. 2 represents a gloss characteristic value (G60) that makes the “glossiness” the same. (This is called “ideal relationship” in this application.)
In the area (1), the paper portion and the toner image portion are mixed, and the “glossy” is indicated on the paper (location indicated by (A)) and the image portion (solid image, location indicated by (B)). Gloss characteristic values having the same “feel” are indicated by A and B, respectively. In the section of the area (1), as described above, the gloss characteristic value having the same “glossiness” changes according to the ratio between the paper portion and the toner image portion, so that (A) and (B) This is represented by a straight line connecting the two.
On the other hand, in the area (2), the toner amount is increased or decreased while the paper is covered with the toner, and the image portion (solid image, the portion indicated by (B)) and the highest density portion (shown by (C)). Gloss characteristic values having the same “glossiness” are indicated by B and C, respectively. In the area (2), since the entire surface is covered with toner, the same gloss characteristic value may be set in order to make the “glossiness” the same. Therefore, the gloss characteristic value is the same between (B) and (C).
Therefore, as shown in FIG. 2, the ideal relationship is expressed as a relationship between the gloss characteristic value and the adhesion amount characteristic value by two straight lines representing the region (1) and the region (2). As described above, this leads to the ability to express gloss characteristic values having the same “glossiness” for all adhesion amount characteristic values.

Furthermore, the evaluation value relating to the glossiness of the evaluation object can be evaluated based on the difference between the ideal relationship defined by the two straight lines and the actual measurement data obtained by measuring the actual evaluation object.
In the present invention, it is evaluated whether or not “glossiness” is consistent in the entire image including various colors. This is different from the prior art which aims to specify the glossiness of one image pattern.
At this time, even if the gloss characteristic value (G60) is the same between the paper and the image portion, the problem that the “glossiness” does not match has been a major obstacle. Therefore, by paying attention to the difference between the ideal relationship and the actually measured data, it is possible to evaluate whether the “glossiness” matches or does not match for the various colors constituting the image. That is, by paying attention to the difference between the ideal relationship and the measured data, an evaluation index having a good correspondence with “glossiness” can be obtained.

By utilizing this, it is possible to evaluate “glossiness” even for different colors (image patterns realized by different amounts of toner adhesion).
By analyzing the coincidence and non-coincidence of the “glossiness” of these individual colors, it is possible to evaluate the uniformity and nonuniformity of the “glossiness” of the entire image.
In addition, by focusing on the difference between the ideal relationship defined by the two straight lines and the actual measurement data obtained by measuring the actual evaluation object, it is possible to evaluate the “glossiness” of the evaluation object, thereby enabling the entire image to be evaluated. As a result, the gloss evaluation device 40 and the gloss evaluation method can be realized.
In addition, since it is possible to generally use characteristic values such as glossiness (G60, 60 degree glossiness) as gloss characteristic values, there is an advantage that no special measurement / measurement equipment is required. ing.

For each patch of the image to be measured to be evaluated in the present invention, the lightness measurement device 20 and the G60 measurement device 30 perform measurement.
FIG. 3 is a diagram showing a patch of an image to be measured that is evaluated in the present invention. An image to be measured to be evaluated by the gloss evaluation device 40 and the gloss evaluation method of the present invention is an image composed of 11 patches having different adhesion states as shown in FIG.
This target image corresponds to the CMYK color data defined by the area ratio values shown in the figure (however, color data that does not use C), and this CMYK color data is output by an image output device. Was the target image.
As can be seen from FIG. 3, the image to be evaluated is “recording medium (hereinafter simply referred to as“ paper ”) portion” (number 0) → “secondary color red” (number 5) → “secondary color red”. It is configured by a color patch connecting “+ K locations” (number 10).
In the region between “paper portion” → “secondary color red”, the surface state of the toner image is a state in which a portion where the surface of the paper is exposed and a portion covered with toner are mixed. .
In the region between “secondary color red” → “secondary color red + K”, the surface state of the toner image is such that the surface of the paper is completely covered with toner. In other words, the image to be evaluated here is an area in which the toner surface on the paper changes with the surface state of the image mixed with the paper and the toner portion, and the surface state of the image is completely covered with toner. And an area where the amount of toner changes.
Various images (various colors constituting the image) output by the image output device are reproduced by changing the amount of toner deposited on the paper. The toner adhesion state on the paper corresponding to these various images is a state in which the surface state of the image is a mixture of the paper and the toner portion as described above from the viewpoint of whether or not the paper is covered with toner. Thus, it can be roughly divided into two areas: an area where the amount of toner on the paper is changing, and an area where the surface state of the image is completely covered with toner and the amount of toner is changing.
For this reason, the evaluation target image here includes these two regions.

The gloss evaluation device 40 and the gloss evaluation method of the present invention evaluate the “glossiness” of the entire image, but evaluating all of the colors realized by various toner adhesion states is, for example, all colors. Since it is necessary to evaluate 10 million colors or more, it is not realistic.
However, as described above, the colors realized by such various toner adhesion amount states are roughly divided into two regions from the viewpoint of whether or not the paper is covered with toner. Therefore, by evaluating each of these two areas, it is considered that the “glossiness” of the entire image can be evaluated from a small number of target patches. In addition, since the evaluation target image of the present invention is configured to include these two regions, the evaluation reflecting the “glossiness” of the entire image can be performed by using the evaluation target image.
Since the evaluation image here does not use cyan, the gloss characteristics regarding cyan are not reflected at all. However, in many image forming apparatuses, for the three colors of cyan, magenta, and yellow, the toner characteristics are hardly set to be different for each color, and characteristics other than the color (spectral reflectance) are very close. It is often a characteristic. For this reason, although cyan is not used in the evaluation image, cyan and magenta / yellow often have similar characteristics (similar surface reflection characteristics) with respect to gloss. Can be evaluated.

Here, the lightness L ^* and G60 are measured by the lightness measuring device 20 and the G60 measuring device 30 for each of the 11 patches in the evaluation target image. The measurement results for the 11 patches are sent to the gloss evaluation apparatus 40 shown in FIG.
The gloss evaluation apparatus 40 first defines a function determined by two straight lines having an ideal relationship from these measurement results. Since this ideal relationship is determined by the following three locations, the brightness of these three locations (A) paper (the state where no toner is attached), (B) secondary color solid portion (C) highest density location Determine the values of L ^* and G60.

Moreover, the problem caused by the phenomenon that “glossiness” does not become the same only by matching the gloss characteristic value such as G60 between the paper and the image portion is solved, and the entire image realized by a combination of various colors is solved. The effect is that the uniformity of “glossiness” can be evaluated.
In addition to this, since characteristic values such as glossiness (G60, 60 degree glossiness) can be generally used as gloss characteristic values, no special measurement / measurement equipment is required.
Further, the most characteristic configuration is that the function defined as the ideal relationship is determined by the locations corresponding to the three toner adhesion states. Of these three locations, two locations, (A) paper location and (C) highest density location, correspond to the lower limit and the upper limit of the amount of toner disposed on the paper, respectively. For this reason, since (A) the paper location and (C) the highest density location are used, all the states of adhesion on the paper fall between these two locations. It is most suitable for the purpose of evaluating the uniformity of “feel”. In other words, no matter what the toner adhesion state on the paper is, it is defined as a function defined as an ideal relationship, so evaluation of whether the “glossiness” is consistent or shifted Can be done.
Further, the remaining one of the three locations is (B) a secondary solid color location. (B) Since the secondary color solid portion is a patch (color) that has been comparatively frequently measured as a gloss evaluation in the past, it is easy to compare with the gloss evaluation results in the past. Can be mentioned. The background in which the secondary color has become the mainstream for gloss evaluation is a secondary color compared to the primary colors C (cyan), M (magenta), Y (yellow), K (black), and the like. It is expected that R (red), G (green), and B (blue) are colors that are used more frequently when a normal image is formed. (Because the color space of the output device is CMYK, the color space of digital cameras, displays, etc. is RGB, which often goes through the RGB color space.) In particular, R (red) is the focus of attention. Because it is used frequently in images that you want to collect (such as company logos), it is regarded as important. For these reasons, since the (B) secondary color solid portion is taken up as described above, it is possible to perform an evaluation focusing on frequently used colors, and thus reflect the uniformity of “glossiness” as the entire image. Can be realized.
As described above, since the lower limit and the upper limit of the amount of toner arranged on the paper are defined, the effect that the “glossiness” can be evaluated even if the toner adhesion state on the paper is abnormal. Is obtained. Further, since the evaluation is based on the secondary color which is a frequently used color, it is possible to easily evaluate the uniformity of the “glossiness” of the entire image.

Further, in the present invention, the glossiness at “(B) secondary color solid portion” and “(C) highest density portion” among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship. The characteristic value is the same. In contrast to the fact that the glossiness value such as G60 is not the same between the paper and the image portion, the “glossiness” is not the same. The uniformity of “feel” can be evaluated.
This is because the gloss characteristic values in “(B) secondary color solid portion” and “(C) highest density portion” are the same among the three toner adhesion states that determine the function defined as the ideal relationship. This is the most characteristic point.
For example, between “(B) secondary color solid portion” and “(C) highest density portion”, the surface of the paper is completely covered with toner, and the toner on the paper is changing. It is. Therefore, since the surface of the paper is completely covered with toner at any location within this range, it is considered that the characteristics of the reflected light beam from the image surface are the same at any location.
Therefore, when focusing on the reflected light beam from the image surface, “(B) secondary color solid portion” and “(C) highest density portion” are different from the case of the paper and the image. When the “feel” is the same, the reflection characteristics are considered to be the same, and at the same time, the gloss measurement value (G60) is also assumed to be the same value. For these reasons, it can be considered that “(B) secondary color solid portion” and “(C) highest density portion” have the same gloss characteristic value with the same “glossiness”.
On the other hand, among the three toner adhesion states that determine the function defined as the ideal relationship, substantially two states may be determined ((B) the secondary color solid portion and (C) the highest density portion. Is automatically calculated from either one), so that the work necessary for determining the ideal relationship can be simplified. That is, it is possible to obtain an effect that the work of determining the ideal relationship can be simplified.

Since patch number 0 corresponds to the paper portion, the measured value of L ^{* and} the value of G60 of patch number 0 are the values of “(A) paper location” in the ideal relationship described above.
Next, the value of G60 (here, Gr) of “(B) secondary color solid portion” is determined by the following procedure.
The value of G60 of “(A) paper location” is the G60 measurement result of patch number 0, and this is Gp. Using this Gp value, the Gr value is determined by the relationship Gr = 0.6 × Gp + 21.

Further, the value of the lightness L ^* of “(B) secondary color solid portion” is the value of the lightness L ^* read from the patch number 5.
That is, the lightness L ^* value of the measured data of the lightness L ^* value and patch number 5 of "(B) 2 primary color solid portions" are the same.
Next, the G60 value of “(C) highest density location” is set to be the same as the G60 value of “(B) secondary color solid location”.
Thus, the lightness L ^* value of "(C) the maximum concentration point" is the lightness L ^* value read from the patch number 10.
As described above, the lightness L ^* and the value of G60 at the three locations described above are determined, so that the target ideal relationship is determined.

An evaluation value of the target image is generated using this ideal relationship. The procedure will be described below.
FIG. 4 is a diagram for explaining the evaluation according to the present invention.
As shown in FIG. 4, the ideal relationship between the adhesion amount characteristic value and the gloss characteristic value is an example of a relationship with actual measurement data read from an image patch to be evaluated.
The value of the lightness L ^* read from each of the 11 patches of the evaluation target image is assumed to be Li. (The subscript i represents the patch number and has a value of 0 to 10.)
The value of G60 is Gi. (The subscript i also represents the patch number and has a value of 0 to 10.)
As described above, a function representing the determined ideal relationship is expressed as F (L ^* ).
For each measurement patch, ΔGi which is the difference between Gi, which is the value of G60, and F (Li), which is the value of G60 determined from the ideal relationship with respect to Li, which is the value of L ^* of the measurement patch, is set for all patches. We will calculate about.
ΔGi = Gi−F (Li) (Subscript i represents a patch number and has a value of 0 to 11)
This ΔGi can be either positive or negative.

Next, the maximum value and the minimum value are specified for this ΔGi.
The maximum value and the minimum value are set to a maximum value: ΔGmax and a minimum value: ΔGmin, respectively. FIG. 4 shows an example of ΔGmax and ΔGmin.
Here, the difference between the actual measurement data obtained by measuring the actual toner image and the ideal relationship is considered as the difference in the gloss characteristic value with respect to the same value of the adhesion amount characteristic value, and this is expressed as ΔGi (subscript i is a plurality of subscripts i). Gloss evaluation value E is generated by the following formula, where ΔGmax is the maximum value for subscript i of ΔGi and ΔGmin is the minimum value.
When ΔGmax and ΔGmin have different signs, the gloss evaluation value E = | ΔGmax | + | ΔGmin |, and when ΔGmax and ΔGmin have the same sign, the gloss evaluation value E = max (| ΔGmax |, | ΔGmin |). Is done. Here, | a | represents the absolute value of a, and max (a, b) represents one of the larger values of a and b.
As a result, the gloss evaluation device 40 can evaluate the glossiness of the toner image on the paper numerically as an evaluation value.

This solves the problem caused by the phenomenon that “glossiness” does not become the same when the gloss characteristic values such as G60 are matched between the paper and the image portion, and the entire image realized by combining various colors. It is possible to evaluate the uniformity of “glossiness”.
Further, the difference between the actual measurement data obtained by measuring the actual toner image and the ideal relationship is calculated as a gloss evaluation value E, which is one numerical value, by the above calculation formula. In this manner, information on a plurality of locations in the actual toner image (a plurality of locations with different toner adhesion states) can be collected into one numerical value called a gloss evaluation value E. By consolidating the gloss evaluation value E into one numerical value, the toner images can be compared with each other in terms of gloss uniformity, and the entire images can be compared. Such a comparison is difficult unless the characteristics of the entire image are aggregated into one numerical value. In this way, there is an effect that the evaluation of the gloss uniformity of the entire toner image is realized.
Moreover, since the image actually output is an image desired by the user, various images are assumed. In fact, there are images that are concerned about gloss uniformity, and there are images that are less concerned. Examples of images where gloss uniformity is anxious include images where the paper portion and the toner image portion are adjacent and the boundary is clear, and images where the halftone dot portion and the toner image portion are adjacent and the boundary is clear. be able to. As described above, the glossy uniformity image is an image in which a difference in “glossiness” is likely to occur because the toner adhesion state is greatly different. We believe that in some cases we will perceive gloss non-uniformity. At this time, how the toner adhering states are adjacent to each other differs depending on the user and what kind of image is desired, and thus cannot be specified in advance.
For this reason, it is possible to express the uniformity of the “glossiness” by using the location shifted to the uppermost side and the location shifted to the lowest side from the ideal relationship that the “glossiness” is almost the same. It becomes possible. That is, the uniformity of the “glossiness” is evaluated using the measured data that is most deviated vertically from the ideal relationship. This is because even if the position is most deviated vertically from these ideal relationships, depending on the image to be output, it may be possible to arrange them adjacently. As described above, the evaluation apparatus is related to the uniformity of “glossiness” in consideration of the fact that the portions where the difference in glossiness is large are arranged adjacent to each other. That is, the evaluation value relating to the uniformity of the “glossiness” of the entire image can be calculated from the information of the portion where the uniformity of the “glossiness” is most different.
Therefore, the gloss evaluation device 40 that can evaluate the uniformity of the “glossiness” of the entire image realized by a combination of various colors is realized.

In the present invention, the adhesion amount characteristic value is “lightness L ^* ”, and the glossiness characteristic value is “60 degree glossiness (G60)”.
This solves the problem caused by the phenomenon that the “glossiness” does not become the same only by matching the gloss characteristic values such as G60 between the paper and the image portion, and the entire image realized by a combination of various colors. It is possible to evaluate the uniformity of “glossiness”.
Furthermore, “lightness L ^* ” is used as the adhesion amount characteristic value. “Brightness L ^* ” is one of the evaluation values calculated from the reflectance of the image, and is the most common index indicating the characteristics of the image. Since the amount of toner deposited on the image have a correlation with the "lightness L ^*", it is the adhesion amount characteristic value as a "lightness L ^*". Since “lightness L ^* ” is a general evaluation index as described above, the measurement speed is fast, and the measurement can be performed by a relatively small and inexpensive device. Thus, gloss can be evaluated using a general evaluation index such as “lightness L ^* ”.
Further, “60 degree glossiness (G60)” is used as the gloss characteristic value. G60 is also a fairly general index for expressing gloss. Conventionally, G60 has a problem that it cannot express the difference in “glossiness” between paper and toner. However, as in the present invention, by defining the ideal relationship and paying attention to the deviation from this ideal relationship, even if G60 is used, it is possible to represent the “glossiness” matching and mismatching.
Since G60 is also a general evaluation index like the lightness L ^* , the measurement speed is fast, and the measurement can be performed by a relatively small and inexpensive device. Furthermore, compared with the variable angle photometric measurement that has been used to evaluate glossiness in the past, the measurement is so simple that it cannot be compared. Thus, in the present invention, evaluation can be performed using a general gloss characteristic value such as G60.

In the present invention, among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship, the value of G60 at “(A) paper location” is Gp, and “(B) secondary color”. When the value of G60 at “solid place” is Gr, a relationship expressed by Gr = 0.6 × Gp + 21 is established between Gp and Gr.
This solves the problem caused by the phenomenon that “glossiness” does not become the same when the gloss characteristic values such as G60 are matched between the paper and the image portion, and the entire image realized by combining various colors. It is possible to evaluate the uniformity of “glossiness”.
Further, among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship, the value of G60 in “(A) paper location” is Gp, and “(B) secondary color solid location”. When the value of G60 at Gr is Gr, the above relationship is established between Gp and Gr.
This relational expression characterizes the relationship in which the “glossiness” is the same between the G60 value of the paper and the G60 value of the toner image patch. Therefore, by using this relational expression, it is possible to specify the G60 value of the solid patch having the same “glossiness” simply by measuring the G60 of the sheet. That is, it is possible to determine the value of G60 at the secondary color patch location in the above-described ideal relationship only by measuring G60 of the paper. This means that for the work of determining the ideal relationship, the value of G60 at the secondary color patch location can be determined simply by measuring G60 of the paper, so that the work can be reduced.

Further, in the present invention, among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship, the value of G60 at “(A) paper location” is Gp, and “(C) maximum density”. When the value of G60 at “location” is Gd, the relationship defined by Gd = 0.6 × Gp + 21 is established between Gp and Gd.
This solves the problem caused by the phenomenon that “glossiness” does not become the same when the gloss characteristic values such as G60 are matched between the paper and the image portion, and the entire image realized by combining various colors. It is possible to evaluate the uniformity of “glossiness”.
Further, the function determined by the two straight lines defined as the ideal relationship is determined. Among the three toner adhesion states, the value of G60 at “(A) paper location” is Gp, and “(C) highest density location”. When the value of G60 is Gd, the above relationship is established between Gp and Gd.
This relational expression is the previous relational expression of Gr, in which Gr is replaced with Gd. That is, Gr and Gd are equal values. This means that, among the three toner adhesion states that determine the ideal relationship, in “(B) Secondary color solid” and “(C) Highest density portion”, the toner covers all the paper surface. The two states are the same. Therefore, in the comparison of the two toner adhesion states, it is considered that the value of G60, which is the gloss characteristic value, is the same if the “glossiness” is the same. For this reason, by setting Gr, which is the value of G60 in “(B) secondary color solid”, and Gd, which is the value of G60 in “(C) deepest density location”, to the same value. , It is possible to identify a wrinkle relationship in which “glossiness” is the same in an area between “(B) secondary color solid” and “(C) deepest density location”.
This makes it possible to evaluate the uniformity of “glossiness” of the entire image realized by a combination of various colors. When the G60 value of “(A) paper location” is determined, “(B) secondary color solid location” and “(C) highest density location” are uniquely determined by the relational expressions described above. It is determined. In other words, the ideal relationship that is one of the points in the present invention can be easily obtained simply by obtaining G60 of “(A) paper location”, and the work of specifying the ideal relationship can be reduced.

<Evaluation method validation experiment>
Example 1
Next, the result of evaluating an actual output image according to the present invention is shown below.
5 to 9 are diagrams showing the relationship between the measured value of the lightness L ^{* and} the measured value of G60 according to the image forming conditions.
In this evaluation experiment, image output is performed under five conditions with different toners and fixing conditions, and the gloss evaluation device 40 of the present invention measures the lightness L ^* and G60 of each patch under the five image forming conditions. The value was measured and the evaluation value was calculated. In order to calculate the gloss evaluation value, the patch images shown in FIG. 3 were output in five image formations. Thereafter, the gloss evaluation value was derived by the gloss evaluation apparatus 40 of the present invention.
On the other hand, the effectiveness of the evaluation method according to the present invention was confirmed by visually evaluating a main tube evaluation image output separately under the same image forming conditions and comparing the result with the above-described evaluation value. Two types of images that have been confirmed to be severe with respect to “glossiness” were used for main evaluation. These images include a portion where the high density part (the toner adhesion amount is large) and the highlight to medium density part (the toner adhesion amount is small to medium) are adjacent to each other. It is an image that feels disagreement.
As an example, the boundary portion between the hair and the skin color of a human figure corresponds to such an image. An image including such a part was used for visual confirmation.
Here, the image forming conditions and toner characteristics in FIGS. 5 to 9 do not matter, and it is sufficient that the gloss evaluation value corresponds to the visual evaluation result, and the effectiveness of the evaluation value can be verified.
Table 1 lists the results of visual evaluation of “glossiness” on the main pipe evaluation images and the numerical values of the gloss evaluation values according to Example 1.

As shown in Table 1, those with a relatively good visual evaluation of “glossiness” are in the upper part of the table, and conversely those with a relatively poor visual evaluation of “glossiness” are in the lower part of the table. The order of arrangement is determined so as to be arranged.
From Table 1, since the gloss evaluation value increases as the target evaluation deteriorates, it can be read that the evaluation values of Example 1 correspond in order to this visual evaluation.
Therefore, the gloss evaluation value presented as Example 1 can accurately represent the “glossiness” of the entire image.
The experiment presented as the evaluation result was for one type of paper (POD gloss coated paper made by Oji Paper Co., G60 = about 27%), but other than this, the G60 of the paper itself is G60 = 5-40%. The same experiment is performed for the sheets in the range, and the effectiveness of the evaluation method of Example 1 is confirmed.

(Derivation method of relational expression)
A relational expression of Gr = 0.6 × Gp + 21 is used as a relational expression between the G60 value Gp of “(A) paper part” and the G60 value Gp of “(B) secondary color solid” part. . This relational expression is derived from the following approach, and specifies a relation in which the “glossiness” is the same between the G60 value of the paper and the G60 value of the toner image patch.
About 300 samples of glossy feeling paper, with solid patches of various colors formed on 12 types of paper selected mainly for coated paper for printing, and fixing and glossing conditions changed.・ Sample patches with different colors were prepared.
Then, the evaluator evaluated the glossiness of the paper portion and the solid patch portion with the five ranks to determine whether they match or do not match. Of the five levels of evaluation, samples (about 40 samples) belonging to the top two levels (2 levels on the side where the gloss is constant) are used, and the relationship between the G60 value of the paper portion and the G60 of the solid patch portion is The relational expression derived by linear approximation by the weighted least square method is the above relational expression.
In this way, the above relational expression is obtained by associating values in which the “glossiness” of the paper in G60 and the solid patches of various colors coincide with each other. By simply measuring G60, it is possible to specify the G60 value of the solid patch having the same “glossiness”.

(Example 2)
Further, in the gloss evaluation apparatus 40 of the present invention, an evaluation experiment can output an image by increasing the number of toners in addition to toner and fixing conditions, and the gloss evaluation apparatus 40 of the present invention can calculate an evaluation value. This further confirmed the effectiveness of the evaluation method according to the present invention.
Here, the image used as the evaluation image is different from that in the first embodiment.
FIG. 10 is a diagram showing a patch of an image to be measured in another example evaluated in the present invention.
In Example 1, as described with reference to FIG. 3, the evaluation image is configured by locations such as a paper location, a red color location (secondary color solid), and a maximum density location (red + black).
On the other hand, the evaluation image of Example 2 is configured by locations such as a paper location, a black solid location (primary color solid), and a maximum density location (4C black) as shown in FIG.
Also in the evaluation image of Example 2, a region where the amount of toner on the paper is changed in a state where the surface state of the image is a mixture of the paper and the toner portion (paper region to black solid region), and the surface of the image Common to the evaluation image of Example 1 in that it can be broadly divided into two regions, a region in which the toner amount is completely covered and the toner amount is changed (a black solid portion to a highest density portion). doing. Therefore, by evaluating each of these two areas, it is considered that the “glossiness” of the entire image can be evaluated from a small number of target patches as in the case of the first embodiment. In other words, the evaluation reflecting the “glossiness” of the entire image can also be performed by using the evaluation target image of the second embodiment.

Therefore, as shown in the first embodiment, it is possible to perform an evaluation image from a paper location to a secondary color solid (may be red or green or blue) to a maximum density location. Further, as shown here, the gloss evaluation device and the gloss evaluation method of the present invention are performed even when an evaluation image such as a paper spot to a primary color solid (cyan, magenta, yellow) to a highest density spot is used. be able to.
Furthermore, the evaluation image is not limited to using an evaluation image composed of eleven patches, and an evaluation image including any other number of patches can be performed. However, if the number of evaluation patches is too small, there will be a problem that evaluation patches will not be arranged in an area where the deviation from the ideal relationship will be large, and conversely, if there are too many evaluation patches, there will be a problem that it will take time to evaluate. Therefore, it is preferable to select an appropriate number. In particular, a number of about 11 is reasonable.

(Example 3)
Here, reflection density (so-called ID) is used as the adhesion amount characteristic, and G20 (20 degree glossiness) is used as the gloss characteristic value.
In Example 3, the adhesion amount characteristic value and the gloss characteristic value different from those in Example 1 are used. However, according to the gloss evaluation device 40 and the gloss evaluation method of the present invention, even when the sheet and the toner image show the same gloss characteristic value because the surface reflection characteristics are different between the sheet and the toner image portion. It pays attention to the point that “glossiness” is not always the same.
An area where the amount of toner on the sheet changes while the surface state of the image is a mixture of the sheet and the toner portion, and an area where the amount of toner changes because the surface state of the image is completely covered with toner. It is shown that it can be evaluated that the “glossiness” is the same by classifying the two areas. In the gloss evaluation apparatus 40 and the gloss evaluation method of the present invention, the adhesion amount characteristic value is not limited to the lightness L ^* , and the gloss characteristic value is not limited to G60. Is possible.
Therefore, as shown in the third embodiment, as in the case of the first embodiment, it is possible to recognize that the surface reflection characteristics are different between the paper and the toner image portion, and to perform the evaluation reflecting the “glossiness” of the entire image. it can.

The third embodiment is different from the first embodiment in the above points, but the other evaluation target images, ideal function determination methods, and gloss evaluation value generation methods are the same as those in the first embodiment.
As the adhesion amount characteristic value, other evaluation values can be used in addition to those described above. For example, it is possible to measure the amount of toner adhering as it is and use “toner weight on paper”, etc. In addition, use “toner layer thickness”, “chromaticity value in color space”, etc. I think you can.
In addition, as the gloss characteristic value, it is also possible to use 45 degree glossiness (G45), 75 degree glossiness (G75), 85 degree glossiness (G85), and the like. Furthermore, an evaluation value related to the angular distribution of reflected light as in the prior art can also be used.

Example 4
Here, using all the number of data of ΔGi (signed and positive and negative values) which are the differences between the ideal relationship and each measured data, the following formula: E = ave (| ΔGi |) (where , | A | represents the absolute value of a, and ave (ci) represents the average value of the subscript i for ci, and the gloss evaluation value E is evaluated.
In the first embodiment, as shown in FIG. 4, the deviation between the ideal function and the actual measurement data is evaluated using two values of ΔGmax (maximum deviation amount) and ΔGmin (minimum deviation amount). The value E is evaluated.
However, here, even with the gloss evaluation value E, the deviation between the ideal relationship and the measured data can be evaluated, so that the uniformity of the “glossiness” of the entire image can be evaluated.
In the fourth embodiment, the above formula is used as a method for generating the gloss evaluation value, but the other evaluation object images and ideal function determination methods are the same as those in the first embodiment, and thus the description thereof is omitted. .
Note that the gloss evaluation of the present invention can also be performed by using, for example, an addition value of | ΔGi |, a square sum of residuals, or the like as an evaluation method similar to that in the fourth embodiment.

(Example 5)
In Example 1, as illustrated in FIG. 4, (B) the gloss characteristic value at the secondary color solid portion and (C) the gloss characteristic value at the highest density portion are the same value. . This is the same in (B) the secondary color solid portion and (C) the highest density portion in that the surface of the paper is completely covered with toner, and thus the surface reflected light characteristics are considered to be the same. Because.
However, (B) the secondary color solid part and (C) the highest density part have the same surface reflected light characteristics, but (B) the secondary color solid part and (C) the highest density part have lightness. Because of the difference in internal reflection light. Internally reflected light refers to a component of incident light that enters the toner layer and is reflected by the paper. Since the internally reflected light passes through the toner layer at the time of incidence and at the time of reflection, the magnitude of this internally reflected light component differs depending on the transmittance of the toner layer. That is, when the lightness is high (bright color), the internal reflection light is large, and conversely, when the lightness is low (dark color), the internal reflection light is small. Yes.
The 60 degree glossiness (G60) is calculated by calculating the value of G60 by irradiating the target patch with light and reading the reflected light. At this time, all incident light is only on the surface of the target patch. Instead of being reflected, a part of the light penetrates into the toner layer and becomes the above-described internally reflected light. Therefore, in addition to the surface reflected light, the internal reflected light is mixed in the measured value of G60. How much internally reflected light is mixed in the measured value of G60 is a problem depending on the color of the patch and the reflectance of the paper. ~ 3 points (glossiness dimension is%, the difference and 2-3% points).
As described above, the contribution of the internally reflected light to the measurement value of G60 is not so large. Therefore, when pursuing the simplicity of measurement, it is also a proposal to ignore the influence of this internally reflected light. . However, in order to match the “glossiness” of the (B) secondary color solid portion and (C) the highest density portion at a higher level, it is desirable to consider the influence of this internal reflection.

FIG. 11 is a diagram for explaining the evaluation according to the present invention.
In Example 5, in order to consider the influence of internal reflection, an ideal relationship different from that in Example 1 is used. FIG. 11 shows the ideal relationship of Example 6. However, a difference of 2-3 points is given in the value of G60 between (B) the secondary color solid portion and (C) the highest density portion. Is set. The reason for this is that, as described above, the (B) secondary color solid portion (red patch) is in a state in which the internally reflected light is mixed as compared with the (C) highest density portion. By setting the ideal relationship by providing such a difference, it is possible to match the “glossiness” between the (B) secondary color solid portion and the (C) highest density portion with higher accuracy.
In the fifth embodiment, by using such an ideal relationship, it is possible to evaluate the uniformity of the “glossiness” of the entire image with higher accuracy than in the first embodiment.
In the fifth embodiment, (B) the gloss evaluation apparatus 40 that generates a gloss evaluation value with high accuracy by canceling the influence of the internally reflected light by taking the case of a red patch as the secondary color solid portion as an example. As a matter of course, when a color other than red is set as the (B) secondary color solid portion, values different from those in Example 6 are set to (B) the secondary color solid portion and (C) the highest density. The ideal relationship must be set by applying to the location. The same applies to the case where the portion (B) is evaluated as a primary color instead of a secondary color.

FIG. 12 is a block diagram illustrating the gloss evaluation method of the present invention.
FIG. 12 shows an outline of a gloss evaluation method (gloss evaluation program). The gloss evaluation method of the present invention is a lightness measurement device 20 and G60 measurement that play a role of measuring each patch of an image to be evaluated. The apparatus 30 and the gloss evaluation apparatus 40 that generates evaluation values are completely independent of each other. The brightness L ^* value and the G60 value are measured using an existing measuring instrument, and only the measured value is received as data to generate a gloss evaluation value.
Many lightness measurement devices 20 and G60 measurement devices 30 have an interface with a PC (computer) or the like, and have already been configured to be able to take measurement data into a PC. In addition, measurement data can be stored in a storage area such as a hard disk in a highly versatile format. The measurement data stored in this way can be transmitted to another PC or the like by various transport means including a network. FIG. 9 shows a configuration in which measurement data measured under such another environment is received and processed by the gloss evaluation device 40 to evaluate the gloss evaluation value.
Here, since an existing measuring instrument can be used to capture measurement data, only the portion for processing the measurement data is necessary for generating the gloss evaluation value. Since this data processing portion can be configured by software or the like, the gloss evaluation value can be evaluated with an inexpensive configuration.

The program of the present invention is a program that causes a computer to execute the gloss evaluation method. For example, the adhesion amount characteristic value and the gloss characteristic value are measured by another measuring instrument, and processing is performed by this program. Thus, it is possible to evaluate the uniformity of the “glossiness” of the entire image realized by a combination of various colors.
Furthermore, the recording medium of the present invention is a storage medium in which a program for gloss evaluation method is stored in a memory, and when the program stored in the storage medium is executed by a computer, it is still possible to use various combinations of colors. It is possible to evaluate the uniformity of the “glossiness” of the entire image to be realized.

20 brightness measuring device 30 G60 measuring device 40 gloss evaluation device

JP 2006-261820 A JP 2007-278919 A JP 2009-68891 A

Claims (16)

In a gloss evaluation apparatus for evaluating the glossiness of a toner image formed on a recording medium,
The gloss evaluation device
From the relationship between the characteristic value corresponding to a plurality of toner adhesion amounts (hereinafter abbreviated as adhesion amount characteristic value) and the characteristic value related to gloss (hereinafter abbreviated as gloss characteristic value),
An ideal relationship predetermined by two straight lines;
A gloss evaluation device characterized by evaluating glossiness based on a difference from actual measurement data obtained by measurement. The gloss evaluation device according to claim 1,
The ideal relationship determined in advance by the two straight lines is determined by locations corresponding to the following three toner adhering states: (A) paper (no toner adhering) location (B) secondary color solid location (C ) Gloss evaluation device characterized by the highest density location. The gloss evaluation apparatus according to claim 2,
Among the three toner adhesion states, the gloss characteristic values at “(B) secondary color solid portion” and “(C) highest density portion” are the same. In the gloss evaluation device according to any one of claims 1 to 3,
The difference between the measured data and the ideal relationship is defined as the difference in the gloss characteristic value with respect to the same value of the adhesion amount characteristic value, which is ΔGi (subscript i represents a plurality of measured data),
When the maximum value is ΔGmax and the minimum value is ΔGmin for the suffix i of ΔGi,
The gloss evaluation value E is evaluated by the following formula. When ΔGmax and ΔGmin have different signs, E = | ΔGmax | + | ΔGmin |
When ΔGmax and ΔGmin have the same sign, E = max (| ΔGmax |, | ΔGmin |)
A gloss evaluation apparatus characterized by that. In the gloss evaluation apparatus according to any one of claims 1 to 4,
The adhesion amount characteristic value is “lightness: L ^* ” (lightness L ^* in CIELAB color space), and the gloss characteristic value is “60 degree glossiness: G60” (60 degree specular glossiness defined in JISZ8741). A gloss evaluation apparatus characterized by In the gloss evaluation apparatus according to claim 5,
Among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship,
The value of the gloss characteristic value (gloss degree G60) at “(A) paper (state where toner is not attached)” is Gp,
When the gloss characteristic value (glossiness G60) at “(B) secondary color solid portion” is Gr,
Gr = 0.6 × Gp + 21
A gloss evaluation device characterized by that The gloss evaluation device according to claim 6,
Among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship,
The value of the gloss characteristic value (gloss degree G60) at “(A) paper (state where toner is not attached)” is Gp,
When the gloss characteristic value (glossiness G60) at “(C) highest density location” is Gd,
Gd = 0.6 × Gp + 21
A gloss evaluation device characterized by that In a gloss evaluation method for evaluating the glossiness of a toner image formed on a recording medium,
The gloss evaluation method is:
From the relationship between the characteristic value corresponding to a plurality of toner adhesion amounts (hereinafter abbreviated as adhesion amount characteristic value) and the characteristic value related to gloss (hereinafter abbreviated as gloss characteristic value),
An ideal relationship predetermined by two straight lines;
A gloss evaluation method characterized by evaluating glossiness based on a difference from actual measurement data obtained by measurement. The gloss evaluation method according to claim 8,
The ideal relationship determined in advance by the two straight lines is determined by locations corresponding to the following three toner adhering states: (A) paper (no toner adhering) location (B) secondary color solid location (C Gloss evaluation method characterized by The gloss evaluation method according to claim 9, wherein
Among the three toner adhesion states, the gloss characteristic value in “(B) secondary color solid portion” and “(C) highest density portion” is the same. In the gloss evaluation method in any one of Claims 8-10,
The difference between the measured data and the ideal relationship is defined as the difference in the gloss characteristic value with respect to the same value of the adhesion amount characteristic value, which is ΔGi (subscript i represents a plurality of measured data),
When the maximum value is ΔGmax and the minimum value is ΔGmin for the suffix i of ΔGi,
The gloss evaluation value E is evaluated by the following formula. When ΔGmax and ΔGmin have different signs, E = | ΔGmax | + | ΔGmin |
When ΔGmax and ΔGmin have the same sign, E = max (| ΔGmax |, | ΔGmin |)
A gloss evaluation method characterized by that. In the gloss evaluation method in any one of Claims 8-11,
The adhesion amount characteristic value is “lightness: L ^* ” (lightness L ^* in CIELAB color space), and the gloss characteristic value is “60 degree glossiness: G60” (60 degree specular glossiness defined in JISZ8741). A gloss evaluation method characterized by that. The gloss evaluation method according to claim 12, wherein
Among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship,
The value of the gloss characteristic value (gloss degree G60) at “(A) paper (state where toner is not attached)” is Gp,
When the gloss characteristic value (glossiness G60) at “(B) secondary color solid portion” is Gr,
Gr = 0.6 × Gp + 21
A gloss evaluation method characterized by the fact that In the gloss evaluation method of Claim 13,
Among the three toner adhesion states that determine a function determined by two straight lines defined as an ideal relationship,
The value of the gloss characteristic value (gloss degree G60) at “(A) paper (state where toner is not attached)” is Gp,
When the gloss characteristic value (glossiness G60) at “(C) highest density location” is Gd,
Gd = 0.6 × Gp + 21
A gloss evaluation method characterized by the fact that A program for causing a computer to execute the gloss evaluation method according to any one of claims 8 to 14. The program according to claim 15 is stored on a memory.
A storage medium characterized by that.