JPS5928856B2 - How to identify printed matter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for identifying printed matter, which is compatible with a wide variety of printed matter and determines whether the printed matter is of the same type or different type by looking at the paper surface of the printed matter.

When identifying printed matter, the commonly used method is to convert the light condition of the printed surface into an electrical signal,
This is compared with the electrical signal on the paper to be compared, and a determination is made as to whether the paper is of the same type or different type. This method includes a static method, in which optical sensors are placed at several points on the paper surface, and the sensor and the paper surface are both fixed and the signal is taken during discrimination, and a static method, which captures the entire image like a television camera. There are dynamic methods, in which changes in light within a certain zone of the paper are taken as a signal by moving the sensor or the paper. In such conventional methods, when operating the comparator circuit, the sensitivity of the detection section must have a considerable range, and depending on the type of printed material, the detection sensitivity may be insufficient, making it impossible to distinguish. Something comes out.

For example, it can be said that it is extremely difficult to distinguish between literary books where the type is arranged in the same way.

Therefore, the object of the present invention is to minimize such inconveniences, provide flexibility depending on the type of printed material, and increase detection ability.

The gist of the present invention is to irradiate light onto the paper surface of a printed matter while moving the paper surface, and receive the reflected light by a light receiving element.
Converts the amount of received light into an analog electrical signal, amplifies the analog electrical signal, converts it into a digital electrical signal, and sequentially stores the digital electrical signals corresponding to numerous positions on the paper surface.
These digital electrical signals are compared with the digital electrical signals at the corresponding positions of other printed matter to be compared, and when the difference between the digital electrical signals at each position exceeds a predetermined level, it is determined to be defective. The purpose is to count the number of defects and determine whether the paper surfaces are the same paper surface or different types of paper based on the ratio of the number of defects to the total number of digital electric signals detected and compared for the paper surfaces to be determined, that is, the defective ratio.

In order to improve the discrimination accuracy, it is first necessary to take a large number of detection points on the paper surface and compare them with those on a standard paper surface.

When extracting the signal from the detection point on the paper and comparing the signal on the standard paper and the signal on the comparison paper, this comparison could simply be made as standard signal E1 (t1) and comparison signal E1' (t1) = 0. If there are irregularities in the paper surface, measurement errors, positional deviations, etc., accurate determination is difficult. Therefore, E1(t1)
=Kl, and as IKkn in advance, n
A tolerance level that is expected to occur when measuring the amount of reflected light at the same position is entered in , and if this is exceeded, it is determined that the signals are not the same, and this is determined to be a defective point. However, even the same paper surface is often microscopically different due to a single spot of dirt or a small area of printing unevenness, and in such cases, multiple defective spots occur.

When two sheets of paper are scanned and reflected light amount signals at individual positions are compared, there will be points where the signals will not be the same even if they are on the same sheet of paper, depending on the position. Therefore, we compare the corresponding positions, tally up the points that are defective, and set the ratio of defective points to all comparison points (in other words, defective ratio) in advance, and the paper is divided based on the defective ratio. A determination is made as to whether the paper is of a different type. In short, the method of the present invention determines how similar the overall shape is as a pattern on the printed surface within a certain area of the paper, and it is possible to determine how similar the overall shape is as a pattern on the printed surface within a certain area of the paper. It is possible to avoid determining that the same paper surface is of a different type even if there is such a problem, and it is also possible to determine that the same paper surface is of a different type when there is large dirt or uneven printing.

Also, there are many different types of printing on paper, but
According to the present invention, the permissible level range at the same position and the degree of similarity of the overall pattern can be arbitrarily set in accordance with a wide variety of printed materials, and accurate judgment can be made in response to a wide variety of printed materials. It can be lowered. Next, the present invention will be explained in detail based on the drawings.

First, the principle of the present invention will be explained with reference to FIG.

One or more sensors A are placed at any position on the printing surface A to be determined.
Set. Then, sensor A is fixed and printing surface A is moved in the direction of arrow 1. (Conversely, it is also possible to move the sensor A in the direction of arrow 2 to make the printing surface A stand still, but in the present invention, either is acceptable, and in this specification, the movement of the paper surface refers to the movement relative to the sensor A.) . Sensor A
is composed of a light source B and a light receiving element C, and as the printed surface A moves, the pattern of the printed surface A changes, and a change in the amount of light received appears on the light receiving element C in accordance with the change in the pattern. It is converted into an analog electrical signal by the light receiving element C.
After this analog electrical signal is amplified by amplifier D,
It enters D converter E, where it is converted into a digital electrical signal. A/D converter E performs sampling at a constant time by clock circuit M. Therefore, if the printing surface A is kept moving at a constant speed, digital electrical signals from new detection points will be output one after another. Such a digital electric signal is stored in the first memory F for each sampling for one sheet of paper.

FIG. 2 shows an example of data of a certain zone, which is sampled and stored from end to end of the printing surface A by moving the printing surface A in this manner.

When such an operation is performed for the first time, if the standard printing surface A is first entered, the data of the predetermined zone of the standard printing surface A is stored in the first memory F.

Next, the printed surface A to be compared and judged is moved and the data at that time is stored in the second memory G.

Furthermore, the data in the first memory F and the second memory G are taken out and input into the clearing circuit H.

This arithmetic circuit H extracts the absolute value of the difference between the input data of the first memory F and the second memory G as a voltage difference. This voltage difference is compared by a level setter 1 set to a desired level in advance and a comparator circuit J, and if the difference between the data in the first memory F and the data in the second memory G is less than the set level, it is determined to be good. , if it is higher than that determination level, it is determined to be defective. For data determined to be defective, only the result of defect is entered into the counter K. If it is good, it is not counted. Such operations are repeated for all data stored in the first memory F and the second memory G in the same order, first for each data, second for each other, third for each data, and so on until the nth data. The defective points are counted by a counter K. When the contents of the first memory F and the second memory G are completely compared, the data of the counter K is input to the arithmetic circuit L. Then, the percentage of the count number of the counter K to the total number n is calculated. A percentage is set in advance as a criterion, and the results of the arithmetic circuit L are compared with the preset percentage to determine whether the printed surfaces are the same or different.

In addition, when starting the memory operation, the surface of the printed paper is detected, and as shown in Fig. 3, when the paper surface enters the sensor A, the first memory F and the second memory G are detected.
It is preferable to start the circuit, and when the paper comes out from the sensor A, stop the circuits of the first memory F and the second memory G, and start the judgment operation.

According to the present invention, as described above, when determining printing, it is possible to minimize detection errors due to local dirt, uneven printing, misalignment of printing, etc. Since the paper surface can be checked accurately over a wide range, the ability to discriminate between different kinds of paper surfaces is increased.

[Brief explanation of drawings]

Fig. 1 is a block diagram for explaining the apparatus for implementing the method of the present invention, Fig. 2 is a waveform diagram showing the flow of detection signals and the level of each detection point, Fig. 3 is a print surface sensor, FIG. 3 is a diagram showing an example of the relationship between a paper surface check sensor and the paper surface of a printed matter.

Claims (1)

[Claims] 1. While moving the paper surface of the printed matter, light is irradiated onto the paper surface, the reflected light is received by a light receiving element, the amount of light received is converted into an analog electrical signal, the analog electrical signal is amplified, and then converted into a digital electrical signal. , sequentially stores digital electrical signals corresponding to multiple positions on the paper surface, compares these digital electrical signals with digital electrical signals at corresponding positions on other printed matter to be compared, and calculates each digital electrical signal at each position. It is determined that the paper is defective when the difference between A method for identifying printed matter characterized by determining whether the last page is the same page or different types of paper.