JP2000034037A - Medium number detection method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium number detection method and system that both detect the number of simultaneously fed media precisely through no or frequent regulations by a light receiving gain regulation means. SOLUTION: This medium number detection system comprises a visible radiation emission element 101, an infrared emission element 103, a visible radiation reception circuit 108 for outputting first signals depending on the intensity of the light from the visible radiation emission element 101, an infrared reception circuit 109 for outputting second signals depending on the intensity of the light from the infrared emission element 103, and a number decision circuit 112 adapted to decide that one medium is being fed if the arithmetic value obtained by the processing of the input first and second signals is not more than a threshold representative of double medium feeding and that two or more media are being fed simultaneously if the arithmetic value exceeds the double medium feeding threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for transporting papers, bills, various films, and the like using light, and more particularly to an apparatus for detecting an overlapped medium.

[0002]

2. Description of the Related Art Conventionally, an apparatus for transporting and managing papers, banknotes, various films, etc. (hereinafter, referred to as a medium) using light, for example, detects the intensity of light having a certain wavelength in order to detect an overlapped medium. Light receiving means for converting into an electric signal is provided. still,
The light referred to here is a laser beam having a small emission wavelength band or a light emitting diode (LE) having a wide emission wavelength band.
D) Use light.

[0003] In this apparatus, the medium is passed one by one on a transport path, the medium blocks light, and the intensity of light received (ie, the light transmittance) is reduced. If the number of media is one based on the signal, count up is performed and the number is counted. In this apparatus, the counting efficiency can be increased by allowing the medium to pass through the transport path at a high speed.

However, what is important in such an apparatus is to count the number of sheets accurately at the same time as counting the number of sheets. In particular, bills, bills and the like must not be miscounted. Therefore, it is necessary to take care not to simultaneously transport a plurality of media that must be transported one by one.

As a device for detecting the simultaneous transport of a plurality of sheets, there is, for example, a medium number detecting device disclosed in Japanese Patent Application Laid-Open No. 8-48439.

FIG. 4 is a block diagram of a conventional medium number detecting device. The light emitting element 401 and the light receiving element 402 are provided so as to be perpendicular to and opposed to a surface to be the transport path 403. The light emitted from the light emitting element 401 is, for example, infrared light. The light receiving element 402 converts the intensity of the received light of a certain wavelength into an electric signal (hereinafter, referred to as a light receiving level).

[0007] The medium 404 and the medium 405 are usually transported by a motor, a belt and rollers (not shown) to the transport path 40.
3 pass one by one. At this time, the light passes through a plane perpendicular to a line connecting the light emitting element 401 and the light receiving element 402. FIG.
In this case, the medium 404 and the medium 405 overlap and the transport path 403
Indicates that the vehicle has passed through.

The light emitting circuit 406 is a circuit for supplying a current for causing the light emitting element 401 to emit light. In addition, the light receiving circuit 407
Is connected to the light receiving element 402 and the A / D converter 408
Is also connected to the number discrimination circuit 409 via the. The light receiving circuit 407 is a circuit that supplies power to the light receiving element 402 that converts the intensity of light into a light receiving level and amplifies the light receiving level.

The A / D converter 408 includes a light receiving circuit 40
The light receiving level output from 7 is sampled and quantized and converted into a digital signal. The number identification circuit 409 is
The number of conveyed sheets is identified based on the digital signal. If it is determined that the number of transported media is one, a count signal (not shown) for counting up is output. If it is determined that two or more sheets have been transported at the same time, a stop signal (not shown) is output to stop the motor and the like, to stop the transport, or to eliminate the medium at that time without counting it.

The light receiving gain adjustment circuit 410 performs feedback to the light receiving circuit 407 based on the digital signal output from the A / D converter 408 to correct the gain of the light receiving level (that is, the power supplied to the light emitting element 402). adjust.

Next, the operation of the medium number detecting device will be described. The operator sets the threshold of the light receiving level when the medium is not conveyed, when one medium is conveyed, and when two mediums are conveyed. When the setting is completed, the medium is transported on the transport path 403. The number discrimination circuit 409 calculates a light receiving level based on the digital signal, and determines the number of media to be transmitted based on the light receiving level. When it is determined that one medium has been transmitted, a count signal is output. If it is determined that two or more sheets have been conveyed at the same time, a stop signal is output to stop the motor or the like to stop the conveyance, or the medium at that time is excluded without being counted. In this way, the medium number detection device detects the number of media.

[0012]

In the conventional medium number detecting apparatus, (1) light emitted from the light emitting means is not constant due to aging, power supply instability, and the like. Even if the condition and quality of the medium are the same, the intensity of the light received by the light receiving means is not always constant. (2) Depending on the temperature characteristics of the light receiving means, there is a difference in the converted electric signal even with the same light intensity. This requires a means such as a light reception gain adjustment circuit for adjusting the gain of the light reception level.

Therefore, even if the same medium passes through the transport path by the same number, it is not always converted to the same light receiving level. Moreover, if the fluctuation is large, the accuracy is lowered. In fact, the received light level fluctuates quickly and requires frequent adjustments. Therefore, it is necessary to minimize the influence of the characteristics of elements and circuits as much as possible. Therefore, it is necessary to adjust the light receiving gain to keep the light receiving level as constant as possible, and there is a new problem that the circuit scale of the device becomes large. However, there is also a problem that efficiency is low.

According to the present invention, there is provided a medium number detecting method capable of accurately detecting the number of simultaneously conveyed mediums without providing adjustment means for adjusting the light receiving gain and without requiring frequent adjustments. It is intended to provide a device.

[0015]

In order to achieve the above object, a method for detecting the number of media according to the present invention comprises irradiating a medium with light of a first wavelength and converting the intensity of light transmitted through the medium into a first signal. The converted value is obtained by irradiating the medium with light of the second wavelength and converting the intensity of the light transmitted through the medium into a second signal, and inputting and processing the first signal and the second signal. If the value is equal to or less than the value indicating the medium overlap, it is determined that there is one medium, and if the calculated value exceeds the value indicating the medium overlap, it is determined that the plurality of media are stacked.

Also, the medium number detecting device includes a first light emitting means for emitting light of a first wavelength, a second light emitting means for emitting light of a second wavelength, and a first light emitting means opposed to the first light emitting means. A first light receiving means provided to output a first signal based on the intensity of light emitted by the first light emitting means; and a light emitted by the second light emitting means provided to face the second light emitting means. A second light receiving means for outputting a second signal based on the intensity of the first light and a first signal and a second signal, when the calculated value obtained by inputting and processing is equal to or less than the value indicating the medium overlap, Is determined to be one,
When the calculated value exceeds the value indicating the medium overlap, a number identification means for judging that a plurality of media are stacked is provided.

[0017]

Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. First Embodiment FIG. 1 is a configuration diagram of a medium number detection device according to a first embodiment of the present invention. The visible light emitting element 101 and the visible light receiving element 102 that emit visible light as the light of the first wavelength are provided so as to be vertically opposed to the transport path 113. The visible light receiving element 102 is, for example, a photodiode, and converts the intensity of a received wavelength in a visible light region into an electric signal.

Similarly, the infrared light-emitting element 103 and the infrared light-receiving element 104 that emit infrared light as the light of the second wavelength are provided so as to be vertically opposed to the transport path 113. The infrared light receiving element 104 is also a photodiode, for example, like the visible light receiving element 102. The infrared light receiving element 104 converts the intensity of a received wavelength in the infrared region into an electric signal.

The visible light emitting device 101 and the infrared light emitting device 10
3 has similar characteristics with respect to temperature and the like. Further, both the visible light receiving element 102 and the infrared light receiving element 104
It has similar characteristics with respect to temperature and the like.

The medium 105 and the medium 106 are usually transported by a motor, a belt and rollers (not shown) to the transport path 11.
3 pass one by one. At this time, the visible light emitting element 101
The light passes through a plane perpendicular to a line connecting the (infrared light emitting element 103) and the visible light receiving element 102 (infrared light receiving element 104). FIG. 1 illustrates a case where the medium 105 and the medium 106 overlap and pass through the transport path 113.

The light emitting circuit 107 is connected to the visible light emitting element 101 and the infrared light emitting element 103,
1 and an electric current for causing the infrared light emitting element 103 to emit light. The visible light receiving circuit 108 is the visible light receiving element 102
And an electric signal (hereinafter, referred to as a visible light receiving level signal) which is connected to the input terminal of the differential amplifier 110 serving as a calculating means and converted by the visible light receiving element 102 based on the intensity of the visible light. , And amplify the differential amplifier 1
10 is a circuit for outputting to one input terminal.

The infrared light receiving circuit 109 is connected to the infrared light receiving element 104 and the other input terminal of the differential amplifier 110, and the infrared light receiving element 104 converts an electric signal (hereinafter referred to as an electric signal) converted based on the intensity of infrared light. , An infrared light receiving level signal), amplifies the signal, and outputs the amplified signal to the other input terminal of the differential amplifier 110.

The differential amplifier 110 outputs to the A / D converter 111 an electric signal (hereinafter, referred to as a differential signal) obtained by calculating a difference between the visible light receiving level signal and the infrared receiving level signal. The A / D converter 111 samples and quantizes the differential signal, converts the signal into a digital signal, and outputs the digital signal to the number identification circuit 112.

The number discrimination circuit 112 discriminates the number of conveyed sheets based on the digital signal. When it is determined that one sheet has been transported, a count signal (not shown) for counting up is output. If it is determined that two or more sheets have been transported simultaneously,
By outputting a stop signal (not shown), the motor and the like are stopped, and the conveyance is stopped.

The medium number detecting apparatus according to the present embodiment utilizes the difference between the transmittance of infrared light and that of visible light for the same number of media (at the same position on the medium). By calculating the difference between the received light levels of infrared and visible light,
A highly accurate detection of the number of simultaneously conveyed sheets is performed while suppressing variations in the light receiving level due to the intensity of the light emitting element, ambient temperature, and the like.

In FIG. 1, for convenience of explanation, the visible light emitting element 101 and the infrared light emitting element 103 are shown separated from each other, but the transmittance under the same conditions (ambient temperature, medium quality, etc.) is shown. Since the purpose is to obtain the difference, they are actually arranged as close as possible.

Similarly, the visible light receiving element 102 and the infrared light receiving element 104 are arranged so as to be as close to the visible light emitting element 101 and the infrared light emitting element 103 as possible.

FIG. 2 is a waveform diagram showing an example of a visible light receiving level signal, an infrared receiving level signal, and a differential signal of the medium number detecting device shown in FIG. 1. The solid line shows light transmission. The respective light receiving levels at normal times and their differences are represented based on the rates. The lower the transmittance, the higher the light receiving level.

(A) shows the waveform of the visible light receiving level signal when there is no medium, when one medium is used, and when two media are used.
The waveform of the infrared light receiving level signal for one medium and two media,
(C) shows the waveform of the differential signal when there is no medium, when the medium is one, and when the medium is two. For visible light, the normal light receiving level value when the medium is not transported is 0, the normal light receiving level value when one medium is transported is 3, and the normal light receiving level when two media are transported. The level value is 4.

As for infrared rays, the normal light receiving level value when the medium is not conveyed is 0, the light receiving level value when one medium is conveyed is 2, and the light receiving level when two media are conveyed. The value is 2.5. Therefore, the value of the difference between the light receiving levels is 0 when the medium is not conveyed, 1 when one medium is conveyed, and 1.5 when two media are conveyed.

Next, the operation of the apparatus for detecting the number of media according to the present embodiment will be described with reference to FIGS. Based on each signal at the normal time shown in FIG. 2, the operator determines a threshold value for distinguishing between when the medium is not transported and when one medium is transported, and when the medium is transported and when the medium is transported. Is 2
A threshold value for distinguishing when a sheet has been conveyed is set in advance. For example, 0.5 is set as a threshold for discriminating when a medium has not been conveyed and when one medium has been conveyed, and 1.1 is set as a threshold for discriminating when two media have been conveyed.

The level of each light receiving level signal is adjusted. This is because the differential signal may have a negative value due to a difference in transmittance depending on the wavelength, and it is necessary to make this a positive value. However, since the setting for making the differential signal positive is complicated, such setting can be simplified by calculating the absolute value in advance.

When the transport of the medium is started, the visible light emitting element 101 and the infrared light emitting element 103 emit light. The visible light receiving element 102 converts the intensity of light of a certain wavelength in the visible light region into a visible light receiving level signal. In addition, infrared light receiving element 1
Numeral 04 converts the intensity of light of a certain wavelength in the infrared region into an infrared light reception level signal.

The differential amplifier 110 calculates the difference between the visible light receiving level signal and the infrared receiving level signal and outputs a differential signal. The A / D converter 111 samples and quantizes the differential signal and converts it into a digital signal.

The number discriminating circuit 112 calculates the difference between the light receiving levels based on the digital signal. If the differential signal is 0.5 or more and less than 1.1, it is determined that the number of media is one and a count signal is output. If the differential signal is 1.1 or more, it is determined that the number of media is two or more, and a stop signal is output, the motor or the like is stopped to stop conveyance, or the medium at that time is counted. Or exclude them without doing so. The above operation is performed to detect a plurality of simultaneous transports of the medium.

Here, for example, the intensity of light emitted from the visible light emitting element 101 and the infrared light emitting element 103 changes, and the light receiving levels of the visible light receiving element 102 and the infrared light emitting element 104 become そ れ ぞ れ each of the normal state. Think about the case.
The waveform diagram shown by the broken line in FIG. 2 shows the light receiving level when the visible light receiving level signal and the infrared light receiving level signal become ／ of the normal state and the difference between the light receiving levels.

For example, consider the case where the number of media is detected only by the visible light receiving level signal in FIG. The light receiving level value when one medium is transported is 2.25, and the light receiving level value when two media are transported is 3. When two media have been transported, the light receiving level value is the same as the light receiving level value 3 when one media has been transported, and it is detected that one media has been transported.

When the number of media is detected only by the infrared light reception level signal, the light reception level value when one medium is transported is 1.5, and the light reception level value when two media are transported. The value will be 1.875. When two media have been transported, the value is smaller than the light receiving level value 2 when one media has been transported, and it is detected that one media has been transported.

On the other hand, when the difference between the light receiving levels is calculated,
The value of the difference when one medium is transported is 0.75,
The value of the difference between the two transported media is 1.125. Since both of them exceed the threshold values 0.5 and 1.1, it can be determined that the medium is conveyed one sheet and two sheets simultaneously.

In the present embodiment, a combination of visible light and infrared light is used as the light wave for calculating the level for detecting the number of sheets. However, the present invention is not limited to this, and the transmission of the same medium to the same position is not limited thereto. Any combination having different rates may be used. For example, a combination of ultraviolet light and infrared light or a combination of ultraviolet light and visible light may be used. Further, they may be in the same light wave region (for example, between visible light rays).

In this embodiment, visible light and infrared light having a wide emission wavelength band are used, but a laser light having a small emission wavelength band may be used.

According to the first embodiment, the difference between the visible light receiving level signal and the infrared receiving level signal converted based on the intensity of the light received by the visible light receiving element and the infrared receiving element is calculated by the difference A dynamic amplifier outputs the signal as a differential signal, converts the signal into a digital signal with an A / D converter, and, based on a difference in the light receiving level represented by the digital signal, a number discriminating circuit compares the threshold with a threshold to determine the number of media. Therefore, the influence of the light receiving level due to the characteristics of the element or the circuit can be suppressed.
Therefore, even if the light receiving levels of the visible light receiving element and the infrared light receiving element are reduced due to, for example, dimming of the visible light emitting element and the infrared light emitting element, the number of media can be detected with high accuracy. Therefore, there is no need to provide means such as a light reception gain adjustment circuit, and the circuit scale can be reduced.
The size of the device can be reduced. Further, it is not necessary to perform the process of adjusting the gain of the light receiving level, and an efficient device can be obtained. There is no need to make further adjustments.

Second Embodiment FIG. 3 is a block diagram of a medium number detecting device according to a second embodiment of the present invention. In this embodiment mode, a white light emitting element is used as the light emitting element. The white light emitting element here emits light of the same intensity at least in the visible light region and the infrared region.

The visible light receiving element 102 and the infrared light receiving element 10
Since the operation of each unit of the medium number detecting device after receiving the light emitted from the white light emitting element 301 is the same as that described in the first embodiment, the description is omitted. .

According to the second embodiment, since the white light emitting element emits infrared light and visible light having the same spectrum intensity, two white light emitting elements having different wavelength bands such as the visible light emitting element and the infrared light emitting element are used. Even if no light-emitting element is provided, one light-emitting element can be used instead, and the number of elements can be reduced.

Third Embodiment FIG. 5 is a block diagram of a medium number detecting device according to a third embodiment of the present invention. This embodiment is different from the first embodiment in that the respective light receiving circuits 108, 10
After the output of No. 9 is converted into a digital signal through A / D converters 111a and 111b, an arithmetic operation of an output ratio is performed by an arithmetic circuit 113 composed of a microprocessor with a memory to identify the number of sheets. .

FIG. 6 is an explanatory diagram of the output ratio of the light receiving level of the medium number detecting device shown in FIG. Medium 105, 106
With a visible light transmittance of 35% and an infrared transmittance of 6
When the number of the media 105 is one when the media 105 is 0%, the media 105
The output ratio of the received light level when the two sheets overlap the medium 106 is as follows.

Visible light emitting element 101, infrared light emitting element 10
When the medium 105 has one light output as the light emission output 100 of 2, the light receiving levels at the time of two sheets are 100 × 0.35 = 35 and 10 respectively.
0 × 0.35 × 0.35 = 12.25, and the medium 10
The light receiving level for each of the six images is 100 ×
0.60 = 60 and 100 × 0.60 × 0.60 = 36.

Accordingly, the output ratio of the light receiving level when one medium 105 is used is 60/35 = 1.71, and the medium 10
The output ratio of the received light level when two sheets 5 and the medium 106 overlap is 36 / 12.25 = 2.94. Therefore, it is possible to detect whether the number of media is one or two by comparing a predetermined value with the output ratio.

FIG. 7 is an explanatory diagram in the case where the light emission output and the light reception sensitivity change due to a temperature change. Visible light emitting element 10
1. When the light output of the infrared light emitting element 102 is reduced to 90 and the light receiving sensitivity is increased 1.3 times,
The light receiving levels at the time of two sheets are respectively 90 × 0.35 × 1.3.
= 40.95, 90 × 0.35 × 0.35 × 1.3 = 1
When the number of the medium 106 is one, the light receiving levels when the medium 106 is used are 90 × 0.60 × 1.3 = 70.2, 9
0 × 0.60 × 0.60 × 1.3 = 42.12.

Accordingly, the output ratio of the received light level when one medium 105 is provided is 70.2 / 40.95 = 1.71, and the output of the received light level when two sheets of the medium 105 and the medium 106 are overlapped is obtained. The ratio is 42.12 / 14.33 = 2.9.
It becomes 4. Therefore, even if the light emission output and the light receiving sensitivity change due to the temperature change, it is possible to detect whether the number of media is one or two by comparing a predetermined value with the output ratio.

According to the third embodiment, whether or not the medium is overlapped can be detected based on the output ratio of the received light level, so that the medium overlap can be detected only by the ratio of the transmittance of the irradiation light to the medium. Therefore, it is possible to detect the overlap of the medium regardless of the change of the output of the light emitting element and the change of the light receiving sensitivity of the light receiving element due to the temperature change.

Fourth Embodiment A block diagram of a medium number detecting apparatus according to a fourth embodiment is the same as that of the third embodiment, except that an arithmetic circuit identifies the number of sheets in an arithmetic circuit. It is.

FIG. 8 is a light receiving circuit diagram of a medium number detecting device according to a fourth embodiment of the present invention. Generally, a light receiving circuit has a limited range in which sensitivity can be obtained. When the phototransistor shown in FIG. 8 receives light, the photocurrent I flows. When the voltage drop RI at the load resistor R becomes equal to the drive voltage V, the level detected becomes constant even when the light is irradiated further,
Will saturate.

Conversely, no photocurrent flows even when light is irradiated that is weaker than the detection capability of the phototransistor. That is, the region of the light receiving sensitivity is the light amount at which the voltage drop RI at the load resistor R becomes equal to the drive voltage V from the minimum light amount that can be detected by the phototransistor. In the present embodiment, detection is performed in consideration of the amount of light outside the light receiving sensitivity range,
The number of mediums can be easily and clearly detected.

FIG. 9 is an explanatory diagram of the detecting operation of the medium number detecting device shown in FIG. The outputs of the visible light and infrared light emitting elements are 100 and 50, and the light receiving sensitivity of the light receiving circuits 108 and 109 is 20 to 40, which is the output range of the light emitting elements. Also,
35% transmittance of visible light to the media 105 and 106,
The transmittance of infrared rays is set to 60%.

When the medium is not present, the light receiving levels are 100 and 50, respectively, and since the light receiving sensitivity exceeds 40, the light receiving circuits 108 and 109 output the light receiving sensitivity as 100%. The arithmetic circuit 113 takes the difference between the two, and
It is.

When one medium exists, the light receiving element 10
Since the light receiving levels of the light receiving circuits 3 and 104 are 35 and 30, the light receiving circuits 108 and 109 have a light receiving sensitivity (35−20) × 100.
/ (40-20) = 75%, (30-20) × 100 /
Output as (40−20) = 50%. Arithmetic circuit 11
In No. 3, the difference between the two is taken, which is 25%.

When there are two media, the light receiving element 10
The light receiving levels of the light receiving circuits 3 and 104 are 12.25 and 18, respectively.
8 and 109 are both output as light receiving sensitivity of 0%. The arithmetic circuit 113 takes the difference between them, and is 0%.

FIG. 10 is an explanatory diagram in the case where the light emission output and the light reception sensitivity change due to a temperature change. Visible light emitting element 10
1. The description will be made on the assumption that the emission output of the infrared light emitting element 102 has been reduced to 90 and the light receiving sensitivity has increased 1.3 times.

Since the light receiving sensitivity has increased 1.3 times,
The range of the light receiving sensitivity is from 20 to 40 to 15.4 (20/1.
3) to 30.8 (40 / 1.3). Further, since the light emission output is reduced to 90, the light receiving levels when no medium is present are 90 and 45, and the light receiving sensitivity exceeds 30.8.
Output as 0%. Therefore, the difference between the two is zero.

When one medium exists, the light receiving element 10
Since the light receiving levels of 3 and 104 are 31.5 and 27,
The light receiving circuits 108 and 109 have a light receiving sensitivity of 100%, (30.
8-27) * 100 / (30.8-15.4) = 75%
Output as Therefore, the difference between the two is 25%.

When there are two media, the light receiving element 10
Since the light receiving levels of the light receiving circuits 3 and 104 are 11.025 and 16.8, the light receiving circuits 108 and 109 have light receiving sensitivity of 0% and (3
0.8-16.8) × 100 / (30.8-15.4)
= 5%. Therefore, the difference between them is 5%.

Therefore, even when the light emission output and the light receiving sensitivity change due to the temperature change, the light receiving sensitivity becomes a large value because:
Since it is the case of one medium, a threshold value, for example, 5% is determined in advance, and it is possible to distinguish between the case where there is no medium, the case where there are two media, and the case of one medium.

According to the fourth embodiment, the number of mediums can be easily and clearly detected by performing the detection in consideration of the range outside the light receiving sensitivity of the light receiving circuit. In the first to fourth embodiments, the present invention is used for an apparatus for counting the number of media. However, the present invention can be used for, for example, a copier or the like to save paper by detecting simultaneous transport of a plurality of papers. .

[0066]

As described above, according to the present invention, the medium is irradiated with light of the first wavelength and the intensity of the light transmitted through the medium is reduced to the first wavelength.
And irradiating the medium with light of the second wavelength to convert the intensity of the light transmitted through the medium into a second signal, and input and process the first signal and the second signal. When the calculated value is equal to or less than the value indicating the medium overlap, it is determined that the number of media is one, and when the calculated value exceeds the value indicating the medium overlap, it is determined that the medium is multiple. This cancels out the fluctuation of the light receiving level due to the temperature characteristic and the like, thereby suppressing the influence of the fluctuation of the signal due to the characteristic of the element or the circuit. Therefore, there is no need to provide a means such as a light reception gain adjustment circuit, and the circuit scale can be reduced, and the size of the device can be reduced. Further, it is not necessary to perform the process of adjusting the gain of the light receiving level, and an efficient device can be obtained. There is no need to make further adjustments.

[Brief description of the drawings]

FIG. 1 is a block diagram of a medium number detecting device according to a first embodiment of the present invention.

FIG. 2 is a waveform chart of the medium number detecting device shown in FIG.

FIG. 3 is a block diagram of a medium number detecting device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional medium number detecting device.

FIG. 5 is a block diagram of a medium number detecting device according to a third embodiment of the present invention.

6 is an explanatory diagram of an output ratio of a light receiving level of the medium number detecting device shown in FIG.

FIG. 7 is an explanatory diagram when a light emission output and a light receiving sensitivity change.

FIG. 8 is a light receiving circuit diagram of a medium number detecting device according to a fourth embodiment of the present invention.

9 is an explanatory diagram of a detecting operation of the medium number detecting device shown in FIG.

FIG. 10 is an explanatory diagram when the light emission output and the light receiving sensitivity change.

[Explanation of symbols]

 Reference Signs List 101 visible light emitting element 102 visible light receiving element 103 infrared light emitting element 104 infrared light receiving element 105, 106 medium 107 light emitting circuit 108 visible light receiving circuit 109 infrared light receiving circuit 110 differential amplifier 111, 111a, 111b A / D converter − Data 112 Number discrimination circuit 113 Operation circuit 301 White light emitting element

Claims (6)

[Claims] 1. A medium number detecting method for irradiating a medium with light and detecting the number of the medium based on the light transmitted through the medium, wherein the medium is irradiated with light of a first wavelength and transmitted through the medium. Is converted into a first signal and a second signal is applied to the medium.
The intensity of the light transmitted through the medium by irradiating light of the wavelength is converted into a second signal, and the calculated value obtained by inputting and processing the first signal and the second signal is a value indicating the medium overlap. In the following cases, it is determined that the number of media is one, and when the calculated value exceeds the value indicating the overlap of the media, it is determined that the plurality of media are stacked. Method. 2. A medium number detecting device for irradiating a medium with light and detecting the number of the medium based on the light transmitted through the medium, comprising: a first light emitting means for emitting light of a first wavelength; A second light-emitting means for emitting light of a wavelength, a first light-receiving means provided opposite to the first light-emitting means and outputting a first signal based on the intensity of light emitted by the first light-emitting means. Means, a second light receiving means provided to face the second light emitting means, and outputting a second signal based on the intensity of light emitted by the second light emitting means; and the first signal When the calculated value obtained by inputting the second signal and the second signal is equal to or less than the value indicating the medium overlap, it is determined that the number of the media is one, and when the calculated value exceeds the value indicating the medium overlap. Comprising a number discriminating means for judging that the plurality of media are stacked. Number detection device. 3. The number-of-sheets discriminating means includes a calculating means for calculating a difference between the first signal and the second signal, and the difference calculated by the calculating means is determined in advance in accordance with the number of sheets of the medium. A number determining unit configured to determine that the number of the conveyed media is one when the value is equal to or less than the set threshold value and to determine that the plurality of media are stacked when the value exceeds the threshold value. 3. The device for detecting the number of media according to 2. 4. The number discriminating means includes a calculating means for calculating a ratio between the first signal and the second signal, and the ratio calculated by the calculating means is determined in advance according to the number of sheets of the medium. If the ratio is less than or equal to the comparison value that is the ratio of the first signal and the second signal, it is determined that the transported medium is one,
3. The medium number detecting device according to claim 2, further comprising: a number determining unit configured to determine that the plurality of media are stacked when the comparison value is exceeded. 5. The medium number detecting device according to claim 2, wherein said first light emitting means and said second light emitting means are white light emitting means for emitting light of at least two different wavelengths. 6. The medium number detecting device according to claim 2, wherein the first light emitting means and the second light emitting means emit light having different wavelengths of infrared light, visible light, and ultraviolet light.