JPH052522Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a paper splicing detector for reliably detecting the splicing position on base paper, for example, in a printing process.

[Prior Art] In the printing process, if printing is performed directly at the splicing position of the base paper, it will not be possible to distinguish it in the next process, resulting in defective products being mixed into the product. Therefore, it is necessary to detect splices in the base paper.
The method of splicing rolled printing paper varies from paper manufacturer to paper manufacturer. For example, this paper splicing is performed as shown in FIG. 3a.
and back paper 1b are connected with double-sided tape 2, or as shown in b, two sheets are stacked and then adhesive tape 3 is attached to the overlapped seam.

When detecting the paper splicing position by projecting light onto the surface of the base paper 1 and detecting the change in the amount of reflected light, it is difficult in the case of a, and easy to detect in the case of b in Fig. If there is vertical fluctuation, detection becomes unstable regardless of the paper splicing method. Therefore, a method is generally used in which a light source and a photoelectric conversion element are separately arranged on the front and back sides of the base paper 1, and the paper splicing position is detected based on changes in the amount of transmitted light.

However, the problem with this method is that the base paper 1
It becomes necessary to maintain appropriate brightness by changing the luminance of the light source in response to changes in the thickness. In other words, if you increase the brightness of the light source with thin base paper 1,
Even when the paper splicing position is reached, the brightness is strong, so there is little change in the amount of transmitted light, or conversely, if the base paper is thick,
If the brightness of the light source is low, even when the paper splicing position is reached, the change in the amount of transmitted light is similarly small and cannot be detected.

Furthermore, the thickness of paper after paper splicing and the mass per unit area of paper are often different from the thickness and mass per unit area of paper before paper splicing. Furthermore, the brightness of the light source changes with long-term use. Therefore, after paper splicing, it is necessary to set new criteria that are suitable for the spliced paper. On the other hand, the paper between one paper splicing part and the next paper splicing part has the same thickness and mass per unit area, but there are slight variations in thickness depending on the location, slight changes in dirt, and there are differences between the top and bottom of the pass line. Due to the fluctuation in the amount of transmitted light, the amount of transmitted light fluctuates slightly.

Therefore, every time the type or thickness of base paper 1 changes,
Appropriate brightness must be selected, and luminance deterioration of the light source over time must also be taken into account when setting the brightness.

Paper splicing detection using this brightness adjustment method is useful in actual printing operations when the line cannot be stopped for adjustment, or when the same base paper continues to be printed and another type of base paper is inserted in between. Sometimes I forget. For this,
There is a need for a paper splicing detector that does not require brightness adjustment even when there are changes in paper thickness or brightness of a light source.

[Purpose of the invention] The purpose of the invention is to reliably detect the position of the paper splice, so that if there is a splice on the base paper during printing work, that position will not be printed or marked. An object of the present invention is to provide a paper splicing detector that does not require brightness adjustment.

[Summary of the invention] The gist of the invention to achieve the above objectives is as follows:
A light source and a photoelectric conversion element are arranged with the base paper on which paper splicing is to be detected sandwiched between them, and the value of the amount of transmitted light detected by the photoelectric conversion element in a steady state without paper splicing is determined by a peak hold circuit and stored as a voltage value. , the value is sent to a comparison/judgment circuit as a judgment reference signal based on a certain voltage division ratio, and the comparison/judgment circuit compares the judgment reference signal with the detection signal of the photoelectric conversion element to determine whether the signal from the photoelectric conversion element is When it becomes smaller than the judgment reference signal, a paper splicing detection signal is output, and the peak hold circuit is reset, and the judgment reference signal obtained by the divided voltage ratio after the reset is set as a new judgment reference signal after the reset. This paper splicing detector is characterized in that it automatically sets a reference value.

[Function] The paper splicing detector according to the present invention having the above-mentioned configuration calculates the maximum value of the amount of transmitted light of the same paper, and calculates the value obtained by multiplying the maximum value by a certain partial pressure ratio. If the amount of transmitted light is lower than the light amount of the determination criterion, it is determined that a paper splicing portion has been detected. When a paper splice is detected, a paper splice detection signal is output, and a reset signal is sent to the peak hold circuit to erase the judgment criteria for the paper up to the paper splice and calculate the thickness and thickness of the paper after the paper splice. Automatically set new judgment criteria corresponding to mass per unit area.

[Embodiment of the invention] The invention will be explained in detail based on the embodiment shown in FIGS. 1 and 2.

As shown in FIG. 1, the embodiment of the present invention consists of a detecting section 10 and a processing section 11. In the detecting section 10, light sources are provided on the front and back sides of the base paper 1, respectively.
2 and a photoelectric conversion element 13 are arranged, and the output of the photoelectric conversion element 13 is sent to the processing unit 1 via an amplifier 14.
1 is sent. The output from this amplifier 14 is connected to a filter amplifier 15 of the processing section 11,
The output a is branched and connected to a comparison/judgment circuit 16 and a peak hold circuit 17. and,
The output b of the peak hold circuit 17 is connected to the resistors R1 and R.
The voltage is divided by a voltage divider consisting of 2 and sent to the comparison/judgment circuit 16 as a signal c. As shown in FIG. 2, the pulse-like output d of the comparison/judgment circuit 16 is sent to the output timer circuit 18, which outputs a signal e with a predetermined time width set by the output timer circuit 18 to the outside, and also holds the peak. It is input as a reset signal to circuit 17 and resets the peak hold circuit. When the reset signal e is input, the peak hold circuit 17 stores the maximum value of the new input a from that point onwards, and continues to output the peak hold signal b to the voltage divider. Further, the output of the light source drive circuit 19 of the processing section 1 is connected to the light source 5 of the detection section 10.

Therefore, when the light source 12 of the detection section 10 is turned on by the light source drive circuit 19 of the processing section 11 , the light beam passes through the base paper 1 and reaches the photoelectric conversion element 13 . The amount of transmitted light is attenuated depending on the type and thickness of the base paper 1, and the amount of light transmitted through the base paper 1 is converted into an electrical signal by the photoelectric conversion element 13 and output, which is amplified by the amplifier 14 and processed by the processing section. Send to 11.

In the processing unit 11, high frequency noise is removed from this input signal by a filter amplifier 15, and the peak hold circuit 17 is output as a signal a as shown in FIG.
is input to the comparison/judgment circuit 16. The waving of the signal a is due to fluctuations in the amount of transmitted light due to vertical fluctuations in the pass line of the base paper 1, slight stains on the base paper 1, and the like. The peak hold circuit 17 is for storing a steady state without paper splicing, and holds the maximum value of the input signal a for the same paper after detecting the previous paper splicing part until detecting the next paper splicing part. The output is the signal b shown by the dotted line in FIG.
sent to. Here, the partial pressure ratio is usually preferably set to 60 to 80% of the output b of the peak hold circuit 17, that is, the maximum transmitted light amount signal for one sheet of paper. The signal of the amount of transmitted light at the paper splicing portion is smaller than this setting signal, and the amount of transmitted light on one and the same sheet of paper is larger than this set value even if it fluctuates.

As shown in FIG. 2, the peak hold signal b is
The output signal c increases each time a new peak value is detected, because a new peak value is stored and the output signal c increases until it is reset by detecting a decrease in the amount of light due to seam detection of the base paper 1.

The comparison/judgment circuit 16 compares the signal a and the output signal c from the peak hold circuit 17, and determines that the signal a is c.
When the value becomes smaller than , a pulsed output signal d is sent to the output timer circuit 18. Here, a decrease in signal a naturally means that the amount of transmitted light has decreased, and this is partially due to the decrease in the amount of transmitted light.
becomes double, indicating that the paper splicing position where double-sided tape or adhesive tape is added has arrived.

The output timer circuit 18 is activated by the output signal d of the comparison/judgment circuit 16, and outputs the signal e with a predetermined time width shown in FIG. Perform a reset.

By this reset, the peak hold circuit 17
Since the peak hold value of the amount of transmitted light of the new base paper 1 after paper splicing is determined, a new setting value corresponding to the change in the thickness of the next new base paper 1 or the deterioration state of the brightness of the light source 12 can be automatically obtained.

Judgment reference signal c is the peak hold value as voltage Vb
Then, Vb・R2/(R1+R2), and the peak hold value is divided by resistors R1 and R2 to create the judgment reference signal c, but the level of this signal c depends on the fluctuation of the pass line,
It is necessary to divide the voltage so that it is lower than the lower limit level of waving of the signal a due to dirt or paper thickness of the base paper 1, and to prevent the comparison/judgment circuit 16 from malfunctioning due to the disturbance signal. Therefore, this determination reference signal c is automatically determined, taking into account the thickness of the base paper 1 and the deterioration state of the brightness of the light source 12, and stable paper splicing detection becomes possible. Note that resistors R1 and R2
The voltage division ratio can also be made variable by using a variable resistor.

[Effects of the invention] As explained above, the paper splicing detector according to the present invention can detect paper thickness by re-memorizing the type of paper thickness without paper splicing and the amount of transmitted light including information on luminance deterioration of the light source. , the paper splicing position judgment criteria are automatically created, and the paper splicing position is reliably detected without the need for external adjustments or reset operations due to the type of paper, paper thickness, or deterioration of the brightness of the light source. can do.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the paper splicing detector according to the present invention, FIG. 1 is a block circuit diagram thereof, FIG. 2 is a time chart, and FIG.
The figure is an explanatory diagram of the paper splicing state. 1 is a base paper, 10 is a detector, 11 is a processing unit,
12 is a light source, 13 is a photoelectric conversion element, 16 is a comparison/judgment circuit, 17 is a peak hold circuit, and 18 is an output timer.

Claims (1)

[Scope of utility model registration request] A light source and a photoelectric conversion element are arranged with the base paper on which paper splicing is to be detected sandwiched between them, and the value of the amount of transmitted light detected by the photoelectric conversion element in a steady state without paper splicing is determined by a peak hold circuit and stored as a voltage value. , the value is sent to a comparison/judgment circuit as a judgment reference signal based on a certain voltage division ratio, and the comparison/judgment circuit compares the judgment reference signal with the detection signal of the photoelectric conversion element to determine whether the signal from the photoelectric conversion element is When it becomes smaller than the judgment reference signal, a paper splicing detection signal is output, and the peak hold circuit is reset, and the judgment reference signal obtained by the divided voltage ratio after the reset is set as a new judgment reference signal after the reset. A paper splicing detector characterized by automatically setting a reference value.