JPS6013249A - Method for inspecting surface of photographic paper - Google Patents

Abstract

PURPOSE:To improve accuracy in detecting defects yielded on the surface of photographic papers, by detecting diffused reflected light from the defective parts on the surface of the photographic paper, and finding the defects by the various change in the diffused reflected light. CONSTITUTION:Light from a light source 10 is reduced by an ND filter 11 and polarized by a rotary scanner 12. The surface of color photographic paper A is scanned by the light through an Ftheta lens 13. As shown in the Figure, in the normal reflected-light region (a), the changes in amounts of light for silk A1 and glossy A2 of the color photographic paper are both large. In the diffused reflected-light region (b), however, the change in amount of light is small. A light receiving part for diffused reflected light 17 is arranged at a position, where the diffused light is detected, as a light receiving part. In this part, a plurality of photomultipliers and preamplifiers, which are operated by a high voltage power source 18, are enclosed. The outputs of the preamplifiers are made to pass an adding amplifier 19 and an HPF20, and a detected signal 21 is outputted. By receiving the light by the diffused reflected-light region in this way, the accuracy of a detect signal 22 is improved, and the detection of the defect is performed accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of inspecting the surface of photographic paper, and more particularly to a method of inspecting the surface of photographic paper for optically inspecting defects occurring on the surface of photographic paper having various surface qualities. be.

Conventionally, as a method for detecting defects that occur on the surface of photographic paper, while the photographic paper is running at a predetermined speed, a laser beam is used as a light source to scan using a flying spot force method, and the reflected light is detected and converted into an electrical detection signal. It is known that when a change occurs in the reflected light after conversion, this is used as a defect signal to detect a defect on the surface of photographic paper.

By the way, there are various types of photographic paper, such as silk, matte, E-side, and glossy, and the reflected light is diffusely reflected and disturbed by this surface quality, which lowers the S/N ratio of the detection signal and makes it difficult to detect defects. There was a problem that the signal could not be received.

This invention was made against the background of the above circumstances, and focuses on the fact that the disturbance of reflected light is caused by specularly reflected light, and detects defects on the surface of photographic paper using changes in diffusely reflected light with less disturbance, thereby generating a detection signal. It is an object of the present invention to provide a photographic paper surface inspection method that can maintain a large S/N ratio, obtain good defect signals, and reliably detect defects in photographic paper having various surface qualities.
The purpose is

To achieve the above object, the present invention provides a method for inspecting defects on the surface of the photographic paper by scanning light from a light source while running the photographic paper and detecting the reflected light. It is characterized by detecting the diffusely reflected light reflected by the sensor, and detecting defects based on changes in this diffusely reflected light.

Hereinafter, embodiments in which the present invention is applied to color photographic paper will be described in detail with reference to the accompanying drawings.

Figure fJS1 is a diagram showing the structure of color photographic paper. The color photographic paper A is manufactured, for example, by simultaneously applying multiple layers of emulsion to which photosensitive dyes have been added, using a slide hopper method, onto a base paper l that is transported at a predetermined speed. The multilayer emulsion layer formed by simultaneously applying multiple layers to the base paper l in this way is
A red-sensitive pan layer 2 that is sensitive to red light, a green-sensitive ortho layer 3 that is sensitive to green light, a blue-sensitive regular layer 4 that is sensitive to blue light, and a protective layer 5 coated on the regular layer 4. The images were drawn from 1000 to 1000 yen, and each was spectrally sensitized. There are various types of color photographic paper A, such as silk, matte, E-side, and glossy, each having a different surface quality.

Color photographic paper A with multilayer emulsion layers formed in this way
is dried in the next drying process, but when applying the emulsion containing photosensitive dyes to the base paper, there may be scratches on the base paper itself, or there may be fibrous substances attached to the base paper. If air bubbles are present in the coating solution, the different colored colorants contained in the pan layer 2, the ortho layer 3, and the regular layer 4 are disturbed, and the color of the surface of the color photographic paper changes and defects appear.

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. Detection roll 6
is provided with a rotary encoder 7, from which a transport pulse is output. By counting these conveyance pulses, the conveyance speed of the color photographic paper is detected, and if the conveyance speed is 0, the shutter is 8
send a signal to close.

A He-Ne laser with a wavelength of 632 nm is used as the light 5 (10) for detecting a defect 9 existing on the surface of the color photographic paper A. This light source 10 uses visible light with a wavelength of 550 nm to 635 nm. and this range d
Visible light in the range has 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 produced on the surface of the color photographic paper A during the manufacturing process.

The light from the light ff11O is attenuated by an ND filter 11, polarized by a rotary scanner 12, and scanned onto the surface of color photographic paper A via an F@L/lens 13. At this time N
A power monitor 14 receives reflected light from the D filter 11 to detect an abnormality in the ND filter 11. If an abnormality occurs, the shutter 8 is closed to prevent fogging. Further, the light reflected by the rotary scanner 12 is detected by a scanner rotation detection device 15, thereby detecting the rotation speed of the rotary scanner 12. If the rotation speed is decreasing, the shutter 8 is closed. 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 relative fluctuations in the scanning light from the rotary scanner 12 for each scan. It has become.

As a light receiving part, a light receiving part 17 for diffuse reflected light is arranged at a position to detect diffused light, and this includes a plurality of photomultipliers that convert the expanded reflected light into electricity operated by a high voltage electric JI 18, It houses preamplifiers arranged in stages for amplification.

As shown in FIG. 3, the outputs of the plurality of preamplifiers are summed by an adding amplifier 19, and then a detection signal 21 is outputted through a bypass filter 20 in order to extract only the defective portion.

If there is a defect on the surface of color photographic paper A, what about the pan layer in this defective area? , the ortho layer 3, and the regular layer 4, the coloring agents of different colors are disturbed and the color of the surface changes. Light hits this defective portion 9, and among the reflected light that is reflected from the defective portion 9, diffused reflected light is received by the diffused reflected light receiving portion 17 to detect the defect.

The relationship between the angle of reflection of reflected light and the amount of light is as shown in Figure 4.
In the specular reflection light region a, the change in light amount is large for both the color photographic papers Silk AI and Glossy A2, but in the diffuse reflection light region the change in light amount 4 is small. Furthermore, in the specular reflection light region a, there is a disturbance in the amount of light for silk AI, and this tendency is also true for other photographic papers such as matte and E-side.

Therefore, if light is received in such a diffuse reflection region,
Since the amount of light is less likely to be disturbed by differences in the surface quality of the photographic paper, the S/N ratio of the detection signal 21 can be maintained high, and the accuracy of the defect signal 22 can be improved.

Note that the photographic paper is not limited to color photographic paper, and can be similarly applied to black and white photographs.

As described above, this invention detects defects on the surface of photographic paper by detecting the diffusely reflected light reflected from defects on the surface of photographic paper, so the amount of light changes due to the surface quality, which varies depending on the type of photographic paper. The influence of this method is small, and the S/N ratio of the detection signal can be maintained at a high level, thereby improving the accuracy of the defect signal and making it possible to reliably detect defects occurring on the surface of various types of photographic paper.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the structure of color photographic paper, Figure 2 is a schematic diagram explaining the state of defect detection in color photographic paper, Figure 3 is a circuit diagram for obtaining a detection signal for defects in color photographic paper, and Figure 4. is a diagram showing the amount of reflected light.

Claims (1)

[Claims] In a method of inspecting defects on the surface of photographic paper by scanning light from a light source while running photographic paper and detecting its warpage (light), detecting diffusely reflected light reflected at defects on the surface of the photographic paper, A photographic paper surface inspection method that detects defects based on changes in this diffusely reflected light.