JPH0334579B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for inspecting the surface of color photographic paper, and in particular to color printing in which emulsion to which light-sensitive dyes are added is simultaneously applied to base paper to laminate multiple emulsion layers. The present invention relates to a color photographic paper surface inspection method for optically inspecting defects occurring on the paper surface.

[Prior Art] Color photographic paper is formed by simultaneously applying multiple layers of emulsion to which light-sensitive dyes have been added to a base paper using, for example, a slide hopper method. This multilayer emulsion layer generally consists of a base paper, a red-sensitive pan layer that is sensitive to red light, and a red-sensitive pan layer that is sensitive to red light.
A green-sensitive ortho layer that is sensitive to green light and a blue-sensitive regular layer that is sensitive to blue light are laminated in this order, and a protective layer is further applied to the surface to produce and spectrally sensitize.

By the way, when applying this photosensitive dye-added emulsion to base paper, if the base paper itself is scratched, fibrous substances are attached to the base paper, or air bubbles are present in the coated emulsion, the quality of color photographic paper may be affected. This causes defects on the surface.

Conventionally, defects occurring on the surface of color photographic paper have been detected by sampling and visual judgment without performing a full-scale inspection, but this is a destructive test, is time-consuming, and is not sufficient for detection.

Additionally, in order to prevent the color photographic paper from being exposed to light, the entire surface is inspected using infrared light, but there is a problem in that the detection power deteriorates significantly in this wavelength range.

[Problems to be Solved by the Invention] After various studies, it was found that due to defects in the color photographic paper, the coloring agent that occurs secondarily is disturbed, and the surface of the color photographic paper is partially discolored. We focused on change.

For example, if it were possible to scan the surface of color photographic paper using visible light of a specific wavelength that does not cause fogging on the color photographic paper, and detect changes in color on the surface of the color photographic paper based on changes in reflectance. We have discovered that it is possible to inspect color photographic papers with different surface qualities for defects without fogging.

This invention was made in view of such circumstances,
A color system that scans the surface of color photographic paper in the visible light wavelength range, which has relatively low sensitivity, and detects color changes in the emulsion layer from changes in the reflected light, allowing for reliable detection of defects without fogging. The purpose of this invention is to provide a method for inspecting the surface of photographic paper.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a method for optically inspecting defects occurring on the surface of a color photographic paper in which a multilayer emulsion layer in which a photosensitive dye is added to a base paper is laminated. The surface of the color photographic paper is scanned with a light source of visible light having a wavelength of 550 nm to 635 nm, and changes in the reflectance of this visible light wavelength are detected to detect changes in the color of the emulsion layer appearing on the surface of the color photographic paper. It is characterized by detecting defects from

[Function] In this invention, the surface of color photographic paper is scanned with a light source of visible light having a wavelength of 550 nm to 635 nm, and the change in reflectance of visible light in this specific wavelength range is detected. Detection of defects in color photographic paper is performed without fogging the paper by utilizing the disturbance of the colorant caused by the defects.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a diagram showing the structure of color photographic paper and the spectral sensitivity distribution of each emulsion layer, and FIG. 2 is a diagram showing the spectral sensitivity distribution of color photographic paper.

The color photographic paper A is constructed by, for example, simultaneously applying multiple layers of emulsion to which light-sensitive dyes have been added to a base paper 1, which is transported at a predetermined speed, using a slide hopper method. The multilayer emulsion layer formed by simultaneously coating multiple layers on the base paper 1 in this way includes a red-sensitive pan layer 2 that is sensitive to red light, a green-sensitive ortho layer 3 that is sensitive to green light, and a green-sensitive ortho layer 3 that is sensitive to blue light. It consists of a blue-sensitive regular layer 4 and a protective layer 5 coated on the regular layer 4, each of which is spectrally sensitized.

This pan layer 2 is exposed to red light with a wavelength of 570nm to 770nm, and ortho layer 3 is exposed to red light with a wavelength of 440nm to 770nm.
The regular layer 4 is exposed to green light with a wavelength of 660 nm.
is sensitive to blue light with a wavelength of 350nm to 510nm, each of which is sensitive only to a specific wavelength range.

Color photographic paper A, on which multilayer emulsion layers have been formed in this way, is dried in the next drying process, but when the emulsion containing photosensitive dyes is applied to base paper 1, the base paper itself may be damaged. Also, if there are fibrous substances attached to the base paper 1 or air bubbles are present in the coating solution, the different colored colorants contained in the bread layer 2, ortho layer 3, and regular layer 4 will be disturbed. , the surface color of color photographic paper changes and appears as a defect.

Detection of defects occurring on the surface of color photographic paper is performed as shown in FIG. Color photographic paper A is conveyed via a detection roll 6 at a predetermined speed. The detection roll 6 is provided with a rotary encoder 7, from which a conveyance pulse is output. By counting these conveyance pulses, the conveyance speed of color photographic paper A is detected,
When the speed is low, a signal is sent to the shutter 8 to close it to prevent fogging.

A He-Ne with a wavelength of 632 nm is used as a light source 10 for detecting a defect 9 existing on the surface of color photographic paper A.
It uses a laser. The light source 10 of the present invention includes this He-Ne laser and has a wavelength of from 550 nm to
Visible light in the 635 nm range is used.

As shown in FIG. 2, visible light within this range d has a relatively low spectral sensitivity. This prevents fog from occurring when the surface of the color photographic paper A is scanned to detect the color of the emulsion layer appearing on the surface of the color photographic paper A during the manufacturing process.

In other words, color photographic paper A is used by printing with light of the three primary colors from negative film, so unlike color negative or positive film, it needs to have a spectral sensitivity that is almost flat (visual sensitivity distribution) over the entire visible light range for performance reasons. In fact, as shown in Figure 2, there is a region of low sensitivity around wavelengths of 550 to 635 nm.

Therefore, this invention utilizes visible light in the wavelength range of 550 to 635 nm to produce color photographic paper A with different surface qualities without fogging, by utilizing the disturbance of colorants caused by defects. However, defect inspection is performed by detecting changes in the reflectance of visible light in this specific wavelength range.

The light from the light source 10 is attenuated by an ND filter 11, polarized by a rotary scanner 12, and then passed through an FΘ lens 1.
3 onto the surface of color photographic paper A.
At this time, the power monitor 14 receives the reflected light from the ND filter 11 to detect an abnormality in the ND filter 11. If an abnormality occurs, the shutter 8 is closed to prevent fogging. Also, rotary scanner 1
The scanner rotation detection device 15 detects the light reflected by the rotary scanner 12, thereby detecting the rotation speed of the rotary scanner 12. If the rotation speed is decreasing,
Close shutter 8. and rotating scanner 1
A mirror 16 is disposed between the rotary scanner 12 and the detection roll 6, which detects the origin of the scanning light and corrects the relative fluctuation of the scanning light from the rotary scanner 12 for each scan. .

The light receiving section is composed of a light receiving section 17 for diffuse reflected light and a light receiving section 18 for specular reflected light, each of which is operated by a high voltage power supply 19 and has a plurality of photomals that convert light into electricity, and a subsequent stage. It houses a preamplifier that is arranged and amplified.

As shown in FIG. 4, the outputs of the plurality of preamplifiers are summed by an adding amplifier 20, and then passed through a high-pass filter 21 to output a detection signal 22 in order to extract only the defective portion. When there is a defect 9 on the surface of the color photographic paper A, the coloring agents of different colors contained in the pan layer 2, the ortho layer 3, and the regular layer 4 in this defect 9 are disturbed and the color of the surface changes. ing. Light hits the defective portion 9, and among the reflected light reflected from the defective portion 9, the diffusely reflected light is received by the diffusely reflected light receiver 17 to detect the defect. Diffuse reflected light is not easily disturbed by the type of color photographic paper A, for example, color photographic paper A has different surface qualities such as silk, matte, E-side, glossy, etc.
The S/N ratio of the detection signal 22 can be maintained large, and the accuracy of the defect signal 23 is improved.

Note that in the case of glossy specularly reflected light, the specularly reflected light is less likely to be disturbed, so the specularly reflected light receiving section 18 may receive the light to detect defects.

Detection of this defect is performed by detecting the color change appearing in the defective part 9 as diffused light,
The pan layer 2, ortho layer 3, and regular layer 4 of the defective portion 9 have reflectances as shown in FIG.

In this invention, we focus on the fact that when a defect occurs in color photographic paper A, the surface of color photographic paper A partially changes color due to the disturbance of the coloring agent that occurs secondarily, and this color change is It is not necessary to identify the color; here, changes in the color of the defect are detected by changes in the reflectance of visible light of a specific wavelength.

Specifically, the spectral distribution of reflectance on the surface of color photographic paper A without defects is curve 5 shown in FIG.
It seems like.

On the other hand, the reflectance spectra of the pan layer, ortho layer 3, and regular layer 4 contain colorants of different colors, so the spectrum of pan layer 2 is curve 2, and the spectrum of ortho layer 3 is curve 2. is curve 3, and the spectrum of regular layer 4 is curve 4. By coating these in a predetermined configuration, the spectral distribution of reflectance on the surface of color photographic paper without defects is as shown in curve 5. It's getting used to me.

The disturbance of the colorant that occurs secondarily due to the occurrence of defects means that the composition of the layer having the spectra of curves 2, 3, and 4 partially changes.

For example, if the number of pan layer 2 decreases compared to the other two layers, ortho layer 3 with a wavelength of around 600 to 700 nm,
The color of regular layer 4 becomes stronger and the wavelength is 600~
A phenomenon occurs in which the spectral reflectance increases around 700 nm.

Similarly, for example, if the number of ortho layer 3 decreases compared to the other two layers, the color of pan layer 2 and regular layer 4 near the wavelength of 500 to 600 nm will become stronger, and the wavelength
A phenomenon occurs in which the spectral reflectance increases around 500 to 600 nm.

Also, as can be seen from this spectral distribution,
At wavelengths below 500 nm and wavelengths above 800 nm, there is little difference in the reflectance of each layer, so even if the colorant is disturbed (partial change in the layer structure), there will not be much change in reflectance at these wavelengths. There's a problem.

Therefore, by changing the reflectance of visible light at a specific wavelength,
To detect color changes on the surface of color photographic paper A,
As can be seen from FIG. 5, the spectrum of the pan layer 2 is curve 2, the spectrum of the ortho layer 3 is curve 3, and the spectrum of the regular layer 4 is curve 4.
Wavelengths from 500nm where the difference in relative reflectance is large
Detection will be performed using the 700nm region.

Therefore, in this invention, by using light in the wavelength range of visible light, and in addition, as described above, in the wavelength range of 550 to 635 nm, color prints with different surface qualities can be produced without fogging the color photographic paper A. Paper is inspected for defects by making use of disturbances in the colorant caused by the occurrence of defects and by detecting changes in the reflectance of visible light in a specific wavelength range.

[Effect of the invention] As mentioned above, this invention has a wavelength from 550 nm to
Since the surface of the color photographic paper is scanned with a light source of 635 nm visible light, it is possible to detect defects on the surface of the color photographic paper using visible light, which has relatively low sensitivity, and capri does not occur during detection.

Moreover, defects can be detected by detecting color changes in the emulsion layer that appear on the surface of color photographic paper based on changes in the reflected light of visible light at specific wavelengths.
The degree of defects can be detected easily and reliably.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the structure of color photographic paper and the specific sensitivity of each emulsion layer, Figure 2 is a diagram showing the spectral sensitivity of color photographic paper, and Figure 3 is a schematic diagram explaining the defect detection state of color photographic paper. , FIG. 4 is a circuit diagram for obtaining detection signals of defects in color photographic paper, and FIG. 5 is a diagram showing the reflectance of each emulsion layer. In the figure, symbol A is color photographic paper, 1 is base paper, 2 is pan layer, 3 is ortho layer, 4 is regular layer, 9 is defective part, 10 is light source, 12 is rotary scanner, 17 is light receiving part for diffuse reflected light , 22 is a detection signal, and 23 is a defect signal.

Claims (1)

[Claims] 1 A method for optically inspecting defects occurring on the surface of color photographic paper, which is made by laminating multiple emulsion layers with photosensitive dyes added to the base paper.
Scans the surface of color photographic paper with a visible light source,
A color photographic paper surface inspection method characterized in that defects are detected from changes in the color of an emulsion layer appearing on the surface of the color photographic paper by detecting changes in reflectance of wavelengths of visible light.