JPH0326762B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for detecting edges of photographic paper, and particularly to a method for detecting edges of photographic paper that easily and accurately detects the edge position of photographic paper in surface detection of wide photographic paper. This invention relates to an edge detection method.

[Prior Art] As is well known, photographic paper is manufactured by applying an emulsion to a wide film base using, for example, the slide drop method, but this emulsion is not applied over the entire surface of the film base, but instead leaves a predetermined width at both ends. It is applied by

If the film base of the photographic paper produced in this manner is scratched or has fibrous matter attached to it, or if air bubbles are present in the coated emulsion, defects will occur on the surface of the photographic paper. For this reason, defects on the surface of the photographic paper are detected using a detection signal obtained by irradiating the photographic paper with a flying spot light source while the photographic paper is being transported, and electrically converting the reflected light from the surface of the photographic paper.

[Problems to be Solved by the Invention] By the way, when detecting this defect, a signal is generated at the edge portion where no emulsion is applied, and this signal cannot be distinguished from the defect signal generated at the defective portion, and is mistakenly recognized as a defect signal. It may be done.

For this reason, conventionally an edge detection mechanism was provided in contact with the edges of the photographic paper to detect the edges of the photographic paper being conveyed, but since it is provided separately from the surface inspection mechanism, the The structure was complex and there were problems with accuracy.

This invention was developed in view of the above circumstances, and it is possible to clearly distinguish the edges of photographic paper from defects when inspecting the surface of the photographic paper, and to detect the edges of the photographic paper by clearly distinguishing them from defective areas and detecting the edges depending on the size of the defective areas and the condition of uncoated areas. It is an object of the present invention to provide a method for detecting edges of photographic paper that is highly reliable and does not cause malfunctions.

[Means for Solving the Problems] In order to solve the above problems, the photographic paper edge detection method of the first invention includes irradiating a light source using a flying spot method while transporting photographic paper having uncoated portions on both sides. A detection signal for detecting defects obtained by electrically converting reflected light on the surface of photographic paper is input to a bandpass filter to obtain outputs corresponding to the uncoated areas on both sides of the photographic paper, and the detection signal is high-pass filtered. The output is input to a filter to obtain a differential output corresponding to the edge of the photographic paper, and a differential output corresponding to the boundary between the uncoated area and the coated area, and then both differential outputs are input to a comparator to obtain an output corresponding to the edge. The edge of the photographic paper is detected by separating the edge and synchronizing the output corresponding to the edge with the output corresponding to the uncoated portion on both sides.

Further, the second invention provides a method for detecting edges of photographic paper,
While transporting photographic paper that has uncoated areas on both sides, a light source is irradiated with a flying spot method, and the reflected light from the surface of the photographic paper is electrically converted, and a detection signal for detecting defects is input to a bandpass filter. to obtain an output corresponding to the uncoated portions on both sides of the photographic paper, and input the detection signal to a high-pass filter to obtain a differential output corresponding to the edge of the photographic paper;
Obtain a differential output corresponding to the boundary between the uncoated area and the coated area, and then input both differential outputs to a comparator to separate the output corresponding to the edge, and separate the output corresponding to this edge from the uncoated area on both sides. The edge signal of the photographic paper is obtained by synchronizing with the output corresponding to The feature is that it is designed to detect.

[Operation] In the first invention, a detection signal obtained by electrically converting reflected light from the surface of photographic paper is input to a bandpass filter to obtain outputs corresponding to the uncoated portions on both sides of the photographic paper. Further, the detection signal is input to a high-pass filter to obtain a differential output corresponding to the edge of the photographic paper and a differential output corresponding to the boundary between the uncoated area and the coated area. These differential outputs are input to a comparator to separate the output corresponding to the edge, and the output corresponding to this edge and the output corresponding to the uncoated parts on both sides are synchronized to obtain an edge signal.
It is possible to obtain an edge signal that is clearly distinguished from a defective portion of photographic paper from the detection signal.

In addition, in the second invention, the output position of the edge signal obtained in the first invention is determined and compared with a set range, and the edge of the photographic paper is detected based on the average value of the output position of this set range multiple times. Even if there is a relatively wide defect in the photographic paper, or even if the emulsion is applied to the edges, the edges can be accurately detected and erroneous detection can be prevented.

[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 relationship between the output waveform at each position of the photographic paper and the edge detection circuit, FIG. 2 is a block diagram showing the edge detection circuit, and FIG. 3 is a block diagram of the malfunction prevention circuit.

Photographic paper A is produced, for example, by simultaneously coating multiple layers of emulsion on a film base that is transported at a predetermined speed using a slide dropper method. This emulsion coating is carried out leaving both ends of the wide film base uncoated, and the uncoated parts 1 and 2 at both ends are cut off in the final step.

The photographic paper A thus formed is dried in the next drying process, but when the emulsion is applied to the film base, the film base itself may be scratched or fibrous substances may adhere to it. If there are bubbles in the coating solution, defects will occur in the coating portion 3. For this purpose, a light source is irradiated in the width direction with a flying spot method while transporting the photographic paper A, and the reflected light from the surface of the photographic paper A is electrically converted to obtain a detection signal. Defects are detected by generating them.

By the way, the detection of defects on the surface of photographic paper A is carried out by scanning not only the emulsion coated part 3 but also the uncoated parts 1 and 2 in the direction of the arrow. In addition to the defect signal, there is an edge signal, and this edge signal is used for uncoated areas 1,
Since emulsion is not applied to 2, it is output,
There is a risk that it may be mistaken as a defective signal.

In this invention, as shown in FIG. 1, when photographic paper A is conveyed in the direction of the arrow and the entire surface of this photographic paper A is scanned in the direction of the arrow, as shown in FIG. Detection signals S1 and S2 are obtained in which the frequency components of the coated portion 1 and the uncoated portion 2 on the left are high.

When these detection signals S1 and S2 are respectively input to the band pass filter 5 as shown in FIG. 2, the uncoated portions 1 and 2 of the edge are
The output of the frequency component corresponding to is obtained. The output of the bandpass filter 5 is further input to a comparator 6 to obtain a pulse output as shown in FIG. 1d.

Further, as shown in FIG. 2, the respective detection signals S1 and S2 are input to a high-pass filter 7,
A differential output corresponding to the edge of the photographic paper A and a differential output corresponding to the boundary between the uncoated areas 1 and 2 and the coated area 3 are obtained as shown in FIG.

The high-pass filter 7 on the right side differentiates the detection signal on the right side, and since the signal has a negative slope in the part a of the frequency component f1 on the right side of FIG. 1a, a falling differential output P1 is obtained. , and Fig. 1a
Since the signal has a positive slope in part b of the frequency component f1, a rising differential output P2 is obtained.

Similarly, the high-pass filter 7 on the left differentiates the detection signal on the left, and the part c of the frequency component f2 of the detection signal S2 on the left in FIG. A differential output P3 is obtained, and since the signal has a positive slope in part d of the frequency component f2 in FIG. 1a, a rising differential output P4 is obtained.

In this way, the differential outputs P1 to P4 are obtained from the left and right high-pass filters 7, and the positive and negative values of the differential outputs P1 to P4 differ between the uncoated portion 1 on the right side and the uncoated portion 2 on the left side. For this reason,
In comparator 8 on the right side, negative comparator α
, and the comparator 8 on the left side multiplies it by a positive comparator β, and as shown in Figure 1e, the differential outputs P2 and P3 corresponding to the boundary between the uncoated parts 1 and 2 and the coated part 3 correspond to the edge. Differential output P1,
P2 is separated and output as a pulse.

Furthermore, on the right side, the output of the comparator 8 is input to a timing circuit 9, which advances a predetermined timing and inputs it to an AND circuit 10, which ANDs the output of the comparator 6 and synchronizes it. , as shown in FIG. 1f, the AND circuit 10 outputs only the right edge signal.

On the left side, the output of the comparator 6 is input to a timing circuit 9, which advances it by a predetermined timing and inputs it to an AND circuit 10.The AND circuit 10 ANDs the output of the comparator 8 and synchronizes it. As shown in FIG. 1F, the AND circuit 10 outputs only the left edge signal.

In this way, the edges of the photographic paper A are detected using the edge signals that have passed through the band pass filter 5 and the high pass filter 7.
It can be clearly distinguished from other defective signals and recognized, and its position can be measured accurately.

By the way, if a relatively wide defect is found during edge detection, it may be mistakenly recognized as an uncoated area of the emulsion, and if the uncoated area is very narrow, it may be recognized as a defective area and an uncoated area. It may not be possible to distinguish between the parts.

For this reason, the edge signal is input to the malfunction prevention circuit. This malfunction prevention circuit will be explained based on FIG.

The entire surface of the photographic paper A is scanned by the flying spot, and the detection signals S1,
S2 is input to the edge detection circuit B shown in FIG. 2, from which an edge signal is output. This edge signal is clocked into register 11. In response to this clock input, the output value of the counter 12 indicating the position of the flying spot is latched in the register 11, and the position where the edge signal is input is taken into the register 11. The output value of the register 11 is then input to comparators 13 and 14. The comparators 13 and 14 cause the switch 15,
The numbers N1 and N2 specified in advance at 16 are compared with the value N output from the register 11.

The specified numbers N1 and N2 have a relationship of N1 > N2, and there is a possibility that the edge signal may fall within a certain width due to the possibility of changing the photographic paper width and meandering when the photographic paper is conveyed. This shows the setting range.

AND circuit 17 only when the output value N from register 11 satisfies the condition N1>N>N2.
A clock is input to the register 18 via the register 18, and the value from the register 11 and the value previously stored in the memory 19 are added together by the adder 20.
The value is taken into register 18. and,
This value is stored in memory 19 again from register 18 .

Then, when the next edge signal is clocked into the register 11 and the output value N from this register 11 is between N1 and N2, the adder 20
The value is added to the value stored in the memory 19, and is sequentially stored in the memory 19 in the same manner as described above.

A counter 21 counts the number of cycles. The input of this counter 21 is the register 11
is given when the output value N from is between N1 and N2. Then, when the counter 21 counts up and overflows by an integral multiple, the register 2
Input the clock to 2. Only in this case, only the upper part of the output of the register 18 is stored in the register 22, and the value that comes out of the register 22 in this way is when the output value N of the register 11 is between N1 and N2, And the average value of multiple scans is shown.

Then, the contents of this register 22 and the contents of the counter 12 indicating the spot position are transferred to a comparator 2.
3, and when the two are equal, a desired edge signal is obtained, thereby detecting the edge of the photographic paper A.

Note that this malfunction prevention circuit is connected to the edge detection circuits of the edge portion of the uncoated portion 1 and the edge portion of the uncoated portion 2. In the malfunction prevention circuit for the uncoated portion 1, since the edge signal of the edge detection circuit is output shifted from the edge position, an adder 24 is placed between the register 22 and the comparator 23 to detect the edge. The comparator 23 is used for comparison according to the position.

[Effects of the Invention] As described above, the first invention electrically converts reflected light on the surface of photographic paper to input a detection signal for detecting defects into a bandpass filter to detect defects corresponding to uncoated areas. At the same time, it is input to a high-pass filter and output corresponding to the edge is obtained from a comparator, and these two outputs are synchronized to obtain an edge signal of the photographic paper. Therefore, when inspecting the surface of photographic paper, edges can be clearly distinguished from defects and can be detected, and can be detected with a simple structure without using any special mechanical mechanism.

Further, in the second invention, the output position of the edge signal obtained in the first invention is determined and compared with a set range, and the edge of the photographic paper is detected based on the average value of the output position in the set range. Even if there is a relatively wide defect in the photographic paper, or even if the emulsion is applied to the edges, the edges can be accurately detected and erroneous detection can be prevented.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the output waveform at each position of the photographic paper and the edge detection circuit, FIG. 2 is a block diagram showing the edge detection circuit, and FIG. 3 is a block diagram of the malfunction prevention circuit. In the figure, symbol A is photographic paper, 1 and 2 are uncoated parts, and 3
4 is a coated portion, 4 is a defective portion, 5 is a band pass filter, 6 and 8 are comparators, and 7 is a high pass filter.

Claims (1)

[Claims] 1. A method of irradiating photographic paper with a flying spot method while transporting photographic paper having uncoated areas on both sides,
A detection signal for detecting defects obtained by electrically converting reflected light on the surface of photographic paper is input to a bandpass filter to obtain outputs corresponding to the uncoated areas on both sides of the photographic paper, and the detection signal is high-pass filtered. The output is input to a filter to obtain a differential output corresponding to the edge of the photographic paper, and a differential output corresponding to the boundary between the uncoated area and the coated area, and then both differential outputs are input to a comparator to obtain an output corresponding to the edge. A method for detecting an edge of photographic paper, characterized in that the edge of photographic paper is detected by separating the edge and synchronizing the output corresponding to the edge with the output corresponding to the uncoated portion on both sides. 2. While transporting photographic paper that has uncoated areas on both sides, a light source is irradiated using a flying spot method,
A detection signal for detecting defects obtained by electrically converting reflected light on the surface of photographic paper is input to a bandpass filter to obtain outputs corresponding to the uncoated areas on both sides of the photographic paper, and the detection signal is high-pass filtered. The output is input to a filter to obtain a differential output corresponding to the edge of the photographic paper, and a differential output corresponding to the boundary between the uncoated area and the coated area, and then both differential outputs are input to a comparator to obtain an output corresponding to the edge. The output corresponding to this edge is synchronized with the output corresponding to the uncoated areas on both sides to obtain an edge signal of the photographic paper.Furthermore, the output position of this edge signal is determined and compared with the set range. A method for detecting edges of photographic paper, characterized in that the edges of photographic paper are detected based on the average value of a plurality of output positions within a set range.