JPS5829075Y2 - Double overlap detection device for printed matter - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a detection device capable of detecting the overlapping of two sheets of printed matter such as banknotes using a simple circuit.

For example, when a banknote is transferred between a light emitter and a light-receiving element in order to detect two overlapping banknotes, and the overlapping of two banknotes is detected from a change in the output of the light-receiving element due to a change in the amount of transmitted light, the pattern on the banknote is printed. When a portion of the light is transmitted between the light projector and the light receiving element, the amount of transmitted light is small, and therefore the output of the light receiving element almost reaches a saturation value.

Therefore, even if two bills overlap, the output of the light-receiving element in the portion where the pattern is printed is almost the same as when there is only one bill.

Therefore, the overlap of two bills is detected by looking at the output of the light receiving element while the part of the edge of the banknote where the pattern is not printed is being transferred between the light emitter and the light receiving element.

The amount of light transmitted is large at the edge of the banknote where the pattern is not printed, and if there is only one banknote, the output of the light-receiving element is considerably lower than the saturation point, so if there are two banknotes overlapped, the light will not be received. The output of the element is considerably greater than if there were only one bill, and it is possible to detect two overlapping bills.

To do this, conventional methods detect when the edge of the bill enters between the emitter and the light receiving element, and at that point operate a relay to close the output circuit of the light receiving element and take out the output. When the part without pattern printing passes between the emitter and the light-receiving element, the output circuit of the light-receiving element is opened by a relay, and in this way, the output of the light-receiving element is seen when the edge of the bill passes. Ta.

However, this requires a timing circuit to operate the relay for a predetermined period of time, and a detection circuit to detect when the leading edge of the bill enters between the light projector and the light receiving element.

The purpose of this invention is to provide a device for detecting the overlap of two sheets of printed matter, which does not require the conventional timing circuit and detection circuit described above.

In order to achieve the above object, this invention includes a differentiator circuit into which the output signal of the light receiving element is input, and a comparator circuit that generates an output signal when the output signal of the differentiator circuit is equal to or higher than a predetermined reference value. The reference value of the comparison circuit is set to be larger than the peak value of the output of the differentiating circuit, which occurs when the unprinted part at the leading edge of one printed sheet passes the position of the light receiving element, and when two printed sheets overlap, the leading edge is printed. The value is selected to be smaller than the peak value of the output of the differentiating circuit that occurs when the portion without the light passes through the position of the light receiving element, and the output signal of the comparison circuit is used to detect the overlap of two sheets of printed matter.

Examples illustrating this invention will be described in detail below.

FIG. 1 is an electrical connection diagram showing the configuration of one embodiment of this invention, in which 1 is a light projector (light emitting diode), one end of which is applied a power supply voltage Vcc through a resistor 2, and the other end of which is applied a power supply voltage Vcc through a resistor 2. is grounded.

3 is a light-receiving element (phototransistor), to the collector of which a power supply voltage Vcc is applied via a resistor 4;

5 is a capacitor, and 6 is a resistor. The capacitor 5 and the resistor 6 constitute a differential circuit, and one end of the capacitor 5 is connected to the collector of the transistor 3.

This differentiating circuit has a large time constant. I is an operational amplifier, the output of the differentiating circuit (5, 6) is input to the negative input side, and the reference value voltage for comparison is input to the positive input side.

The operational amplifier I is used as a comparator, and the power supply voltage Vcc is applied to its output side via a resistor 18, and the output terminal 8 is connected to this output side.

A banknote 9 is transferred between the light emitting diode 1 and the phototransistor 3 in the direction of the arrow 10.

Next, the operation will be explained.

Light emitted from the light emitting diode 10 is applied to the phototransistor 3.

The impedance of the phototransistor 3 decreases as the amount of incident light increases.

Therefore, while the banknote 9 is not inserted, the amount of light applied to the phototransistor 3 is maximum, so the impedance is minimum, and the collector potential (potential at point A) is minimum.

When a banknote is inserted, the edge of the banknote is located at the unprinted part (hereinafter referred to as the white part).

) is passing between the light emitting diode 1 and the phototransistor 3, the amount of light transmitted is slightly S, and the impedance of the phototransistor 3 does not become very large.
When the white part ends and the patterned part passes between the light emitting diode 1 and the phototransistor 3, the amount of transmitted light becomes extremely small, so the impedance of the phototransistor 3 becomes sufficiently large, and the potential at point A is almost the same as the power supply. It reaches a value close to the voltage and reaches saturation.

In Figure 2A, from time t1 to t2t, the potential at point A is shown when the white part at the tip of the bill passes, from t2 to t3t, the potential when the patterned part passes, and from t3 to tit. , shows the potential at point A when the white part at the rear end passes.

However, this applies to the case where there is only one banknote.

When two banknotes are stacked on top of each other, the potential at point A is as shown in Figure 3A.

However, at times tl', t2', and t3 in Fig. 3A,
', t4' are the respective time points tl and t in Fig. 2A.
2. t3. This corresponds to t4.

As can be seen from the above, from time t2 to t3 (from t2' to t3
')'! In this case, whether there is one banknote or two banknotes, the potential at point A almost reaches saturation, so there is almost no difference.

Note that the symbol 0 (V) in FIGS. 2 and 3 means zero volt.

The potential at point A shown in FIG. 2A or FIG.

This differential output is shown in Figures 2 and 3.

However, these curves are approximate curves when the time constant of the differentiating circuit (5, 6) is set large.

When transferring a bill between the light emitting diode 1 and the phototransistor 3, when the tip of the bill reaches the position of the phototransistor 3, the amount of light applied to the phototransistor 3 changes by blocking the light emitted from the light emitting diode 1. is the largest, and compared to this, changes in the amount of light applied to the phototransistor 3 are small depending on the shading of the printed pattern on the banknote.

Therefore, the output of the differentiating circuit C5, C6) is maximum when the leading edge of the banknote passes through the phototransistor 3.

However, by increasing the time constant of the differentiating circuit (5, 6), the output curves can be made as shown in Figures 2 and 3.

As shown in these figures, when the white part at the tip of the bill passes between the light emitting diode 1 and the phototransistor 3, the potential at point A has not reached saturation, so if there is only one bill The potential at point A is considerably different between the case where the two sheets overlap and the case where the two sheets overlap.

In other words, when there is only one bill, the phototransistor 3 reacts to the white part as if it were blocked by a translucent object, and the output of the phototransistor 3 exhibits a somewhat gradual rise characteristic. On the other hand, when there are two bills, the phototransistor 3 is blocked by an opaque object for the white part, so
The received light output shows a sharp rise characteristic.

Then, when two sheets overlap, A at time t1'
The change in potential at a point is quite large.

Therefore, when the two sheets overlap, the output of the differentiating circuit (5, 6) at time tl' is considerably large.

The reference voltage value input to the positive input side of operational amplifier I is set to 1
It is larger than the output of the differential circuit (5°6) that occurs when the white part of the tip of two banknotes passes the position of phototransistor 3, and the white part of the tip of two banknotes overlaps and the position of phototransistor 3 is greater than the output of the differential circuit (5°6). By selecting a value smaller than the output of the differentiating circuit (5, 6) when the banknotes pass through the bank, the output of the output terminal 8 of the operational amplifier I can be set to a value smaller than the output of the differential circuit (5, 6) when the banknotes pass through It is possible to set the voltage to zero volts only when

This zero volt signal does not appear when there is only one banknote, as shown in FIG.

The zero volt signal applied to the output terminal 8 can be input to a discriminating circuit (not shown) at a subsequent stage, thereby displaying the detection of two overlapping bills.

Although the above description has been made regarding banknotes, printed matter generally has a white portion on the periphery, so this invention can also be applied to general printed matter.

As explained above, with this invention, it is possible to detect overlapping of two printed materials with a simple circuit that does not require a timing circuit or a detection circuit.

In addition, when detecting the output level of the light receiving element in a steady state as with conventional devices, the output in the steady state may become unstable. It is not possible.

However, in this invention, since the differential output of the light receiving element is used, the steady state is irrelevant, and there are advantages in that it is possible to accurately detect two-sheet overlap, and the detection operation is also faster.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram showing the configuration of one embodiment of this invention, and FIGS. 2 and 3 are operation explanatory diagrams. 1... Light emitting diode (light emitter), 2...
...Phototransistor (light receiving element), 5, 6...
... Differential circuit, I... Operational amplifier (comparator).

Claims (1)

[Scope of utility model registration request] A device for detecting overlapping of two printed materials using a light projector and a light receiving element that transmits light emitted from the light projector through the printed matter and receives the light, which comprises: a differentiating circuit to which an output signal of the light receiving element is input; a comparison circuit that generates an output signal when the output signal is greater than or equal to a predetermined reference value; The value is selected to be larger than the peak value of the output of the differentiating circuit that occurs, and smaller than the peak value of the output of the differentiating circuit that occurs when two printed sheets overlap and the unprinted part at the tip passes the position of the light receiving element. An apparatus for detecting double overlap of printed matter, characterized in that when the output signal of the differentiating circuit exceeds the reference value, the output signal generated from the comparison circuit is used as a signal for detecting the overlap of two sheets.