JP2021095255A - Method for adjusting sensitivity of detection sensor - Google Patents

Abstract

To provide a method for adjusting sensitivity of a detection sensor which allows sensitivity to be easily adjusted.SOLUTION: There is provided a method for adjusting sensitivity of a double-feed sensor (118) which has a transmitting part (1181) and a receiving part (1182) and detects a conveyed sheet by an ultrasonic system, in which when applying a reference-setting voltage in a double-feed sensor to be a reference, this method decides a threshold voltage for determining double-feeding of a sheet of a new double-feed sensor (118b) on the basis of a second reference received-voltage (1164) detected by a receiving part (1182b) when applying a reference-setting voltage to the transmitting part in the new double-feed sensor (118b), in addition to a first reference received-voltage (1161) detected by the receiving part (1182), a first received-voltage (1162) detected by the receiving part (1182) in the case where one reference paper interposes, and a second received-voltage (1163) detected by the receiving part (1182) in the case where two reference papers interpose.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for adjusting the sensitivity of a detection sensor, and more particularly to a method for adjusting the sensitivity of a detection sensor that detects conveyed paper by an ultrasonic method.

In recent years, in an image forming apparatus, there is known an image forming apparatus in which a document reading device provided with an automatic document transporting device is arranged so that a plurality of printed documents are automatically read one by one.

In the automatic document transfer device, when the documents are conveyed, whether or not the documents are conveyed one by one is detected by the double feed sensor.

As the double feed sensor, an ultrasonic sensor including a transmitting unit that outputs ultrasonic waves and a receiving unit that receives ultrasonic waves output from the transmitting unit is used.

As a document transporting device using an ultrasonic sensor, in the prior art, in a document transporting device, a separate feeding means for separating and feeding a bundle of sheets into one sheet, a transporting means for transporting the separated sheets, and a sheet double feeding device. A transport path switching means for switching between a first transport path for linearly transporting a sheet and a second transport path for bending and transporting a sheet is provided, and the double feed detection means switches the transport path. A detection condition (for example, a threshold value) used when detecting double sheet feeding is disclosed based on the result of switching means (see Patent Document 1).

With this configuration, by using an ultrasonic sensor as the double feed detection means, it is possible to detect double feed with high accuracy without being affected by the color, material and surface condition of the sheet, so that the weight is high. Since the feed determination can be made strict, stable sheet transport can be performed.

JP-A-2019-104600

However, in the technique described in Patent Document 1, accuracy is required for detection by an ultrasonic sensor in order to perform a double feed determination. Therefore, if there is a variation in detection accuracy depending on an individual ultrasonic sensor, it is important. There is a problem that the transmission detection becomes unstable.

In order to correct variations in detection accuracy depending on the individual ultrasonic sensor, for example, sensitivity adjustment is performed for each sensor by checking the received signal level with the reference paper sandwiched and determining the double feed judgment threshold. is necessary.

Therefore, when it is necessary to replace an ultrasonic sensor in a document transporting device, it is difficult to perform adjustment in the market where the document transporting device is installed because a dedicated reference paper is required.

In addition, since the signal level changes depending on the type of paper and the presence or absence of wrinkles, the reference paper must be strictly controlled.

Therefore, even if only a part of the double feed sensor unit fails, it is necessary to replace the unit set for each adjusted unit, which causes problems such as expensive replacement parts and a large amount of work.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a sensitivity adjusting method for a detection sensor capable of easily adjusting the sensitivity.

The sensitivity adjusting method of the detection sensor of the present invention is a sensitivity adjusting method of a detection sensor including a transmitting unit and a receiving unit to detect paper conveyed by an ultrasonic method, and in a reference detection sensor, the transmitting unit When a reference setting voltage is applied to, the first reference reception voltage detected by the receiving unit and a reference that serves as a reference for paper detection when a detection voltage (for example, a drive voltage) is applied to the transmitter. When a first reception voltage detected by the receiving unit when one sheet of paper is interposed and a detection voltage are applied to the transmitting unit, it is detected by the receiving unit when at least two sheets of the reference paper are interposed. In addition to the second reception voltage to be adjusted, the sensitivity is based on the second reference reception voltage detected by the reception unit when the reference setting voltage is applied to the transmission unit in the detection sensor to be adjusted for sensitivity. It is characterized in that the threshold voltage for determining the double feeding of the paper of the detection sensor to be adjusted is determined.

According to the sensitivity adjustment method of the detection sensor of the present invention, the double feed of the paper in the detection sensor of the sensitivity adjustment target is determined based on the reception voltage of the reference detection sensor and the reference reception voltage of the detection sensor of the sensitivity adjustment target. Since the threshold voltage to be adjusted can be determined, the sensitivity of the detection sensor to be adjusted can be easily adjusted without adjusting the sensitivity using the reference paper.

It is a block diagram which shows the structure of the image forming apparatus which comprises the image reading apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of an image reader. It is explanatory drawing which shows the whole structure of the image forming apparatus. It is explanatory drawing which shows the detection state of the double feed sensor which is the reference of the double feed sensor used for an image reader. It is explanatory drawing which shows the detection state of the reference paper of the double feed sensor which becomes a reference. It is explanatory drawing which shows the detection state of the new double feed sensor which is a sensitivity adjustment target. It is a table which shows the value of the received voltage with respect to the drive voltage of a double feed sensor. It is a graph which shows the relationship between the drive voltage and the reception voltage of a double feed sensor. It is a table which shows the value of the received voltage detected by the reference double feed sensor of an automatic document transfer apparatus. It is a table which shows the value of the received voltage detected by the new double feed sensor to be adjusted. It is a flowchart which shows an example of the procedure of the sensitivity adjustment processing of a new double feed sensor in an image reader. It is a flowchart which shows an example of the procedure of the sensitivity adjustment processing of the new double feed sensor in the image reading apparatus which concerns on 2nd Embodiment. It is a table which shows an example of the table which determines the threshold voltage of the double feed sensor which concerns on 3rd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an image forming apparatus including the image reading device according to the first embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the image reading apparatus, and FIG. 3 is an overall configuration of the image forming apparatus. It is explanatory drawing which shows.

As shown in FIG. 1, the image forming apparatus 10 according to the first embodiment is an image forming apparatus 10 including an image reading apparatus 110 controlled to irradiate a document with light to read an image, and reads an image. As shown in FIG. 2, the automatic document transfer device constituting the device 110 is provided with the double feed sensor 118 and is configured to detect the double feed of the conveyed document.

The double feed sensor 118 is an ultrasonic sensor that includes a transmitting unit 1181 and a receiving unit 1182 to detect a document conveyed by an ultrasonic method.

In the first embodiment, when the double feed sensor 118 is replaced due to a defect such as a document detection failure of the automatic document transport device 112 in the image reading device 110, a new double feed sensor 118b is attached to the image reading device 110. It is characterized in that the sensitivity of the double feed sensor 118 is adjusted without using a reference paper which is a reference for detecting a document.

(Configuration of image forming apparatus)
First, the basic configuration of the image forming apparatus 10 according to the first embodiment will be described.
As shown in FIG. 3, the image forming apparatus 10 is an information processing apparatus provided with an image reading device 110 on the upper portion of the apparatus main body 10a to read an image of a document and output an image by an electrophotographic method.

Then, as shown in FIG. 1, the image forming apparatus 10 mainly includes a control unit 100, an image reading device 110, an image processing unit 120, an image forming unit 130, an operation unit 140, and a display unit 150. , A storage unit 160 is provided.

The control unit 100 is a functional unit for controlling the entire image forming apparatus 10.
The control unit 100 realizes various functions by reading and executing various programs, and is composed of, for example, one or a plurality of arithmetic units (for example, a CPU (Central Processing Unit)).

As shown in FIG. 2, the image reading device 110 mainly includes a control unit 111, an automatic document transporting device 112, a document reading unit 113, a storage unit 116, a double feed sensor 118, and an amplification / smoothing circuit 119. It is configured with and.

The image processing unit 120 is a functional unit that performs various image processing on the image data. Then, an output image is formed based on the image data that has undergone image processing.

The image forming unit 130 is a functional unit for forming output data based on the image data on a recording medium (for example, recording paper). For example, as shown in FIG. 3, the recording paper is fed from the paper feed tray 122, and after the image is formed on the surface of the recording paper in the image forming unit 130, the paper is discharged to the paper ejection tray 124. The image forming unit 130 is composed of, for example, a laser printer or the like using an electrophotographic method.

The operation unit 140 is a functional unit for receiving an operation instruction by a user, and is composed of various key switches, a device for detecting an input due to contact, and the like. The user inputs a function to be used and output conditions via the operation unit 140. Further, the display unit 150 is a functional unit for displaying various information to the user, and is configured by, for example, an LCD (Liquid crystal display) or the like.

As shown in FIG. 3, the image forming apparatus 10 may include a touch panel in which the operation unit 140 and the display unit 150 are integrally formed. In this case, the method for detecting the input of the touch panel may be a general detection method such as a resistance film method, an infrared ray method, an electromagnetic induction method, or a capacitance method.

The storage unit 160 is a functional unit that stores various programs and various data necessary for the operation of the image forming apparatus 10. The storage unit 160 is composed of, for example, a semiconductor memory SSD (Solid State Drive), an HDD (Hard Disk Drive), or the like.

(Configuration of image reader)
Next, the characteristic configuration of the image reading device 110 will be described with reference to the drawings.
As shown in FIG. 2, the image reading device 110 stores a control unit 111, an automatic document transporting device 112 including a double feed sensor 118 and an amplification / smoothing circuit 119, a document reading unit 113 including a light source unit 1132. It is configured to include a portion 116.

FIG. 4 is an explanatory diagram showing a detection state of a double feed sensor as a reference of the double feed sensor used in the image reading device according to the first embodiment, and FIG. 5 is an explanatory diagram showing a detection state of a reference paper of the double feed sensor as a reference. FIG. 6 is an explanatory diagram showing a detection state of a new double feed sensor whose sensitivity is to be adjusted.

The automatic document transport device 112 is a functional unit that automatically transports a plurality of documents, and includes a double feed sensor 118. The double feed sensor 118 includes a transmission unit 1181 and a reception unit 1182 to detect double feed of paper conveyed by an ultrasonic method.

The amplification / smoothing circuit 119 is an electronic circuit for amplifying a minute received signal detected by the receiving unit 1182 of the double feed sensor 118 to a level that can be determined.

The document reading unit 113 is a functional unit for reading image data input from the document to the image forming apparatus 10.

The control unit 111 is a functional unit for controlling the entire image reading device 110.
In the first embodiment, the control unit 111 includes a reception voltage setting unit 1111, a threshold voltage setting unit 1112, and a double feed determination unit 1113.

As shown in FIG. 4, when the reception voltage setting unit 1111 applies the reference setting voltage 1171 to the transmission unit 1181a in the reference double feed sensor (hereinafter, referred to as “reference double feed sensor”) 118a. , The reception voltage detected by the reception unit 1182a is set as the first reference reception voltage 1161.

The detected waveform of the first reference reception voltage 1161 is a minute AC waveform 1161a of several mV to several tens of mV. Since it is difficult to observe as it is, it is amplified to an observable level by the amplification / smoothing circuit 119.

Further, as shown in FIG. 5, the reception voltage setting unit 1111 refers to a reference paper (hereinafter referred to as “reference paper”) that serves as a reference for paper detection when a drive voltage (detection voltage) 1172 is applied to the transmission unit 1181a. The reception voltage detected by the reception unit 1182a when one P is interposed is set as the first reception voltage 1162. Further, the reception voltage detected by the reception unit 1182a when two sheets of reference paper are interposed is set as the second reception voltage 1163.

Further, as shown in FIG. 6, the reception voltage setting unit 1111 is detected by the reception unit 1182b when the reference setting voltage 1171 is applied to the transmission unit 1181b in the new double feed sensor 118b whose sensitivity is to be adjusted. The reception voltage is set to the second reference reception voltage 1164.

Further, in the reception voltage setting unit 1111, the reception voltage detected by the reception units 1182a and 1182b is amplified by the amplification / smoothing circuit 119 to a range where the reception signal level can be confirmed.
The received signal level after the amplification process in the amplification / smoothing circuit 119 is set so as not to exceed the upper limit of the detectable received signal level of the receiving unit 1182.

Reference numeral 1171a in FIG. 4 indicates a transmission waveform of the reference setting voltage 1171, and 1161b indicates an amplification reception waveform of the first reference reception voltage 1161. In FIG. 5, reference numeral 1172a indicates a transmission waveform of the drive voltage 1172, 1162b indicates a reception waveform after amplification of the first reception voltage 1162, and 1163b indicates a reception waveform after amplification of the second reception voltage 1163. Reference numeral 1164b in FIG. 6 indicates a reception waveform after amplification of the second reference reception voltage 1164.

The threshold voltage setting unit 1112 determines the double feeding of the paper of the new double feeding sensor 118b based on the first reference receiving voltage 1161, the first receiving voltage 1162, the second receiving voltage 1163, and the second reference receiving voltage 1164. The threshold voltage (first threshold voltage) 1165 is determined.

The double feed determination unit 1113 determines whether or not the double feed is performed based on the reception voltage detected by the reception unit 1182b of the new double feed sensor 118b and the first threshold voltage 1165.

The control unit 100 that controls the image forming apparatus 10 may function as the control unit 111 that controls the image reading apparatus 110 in general.

As shown in FIG. 2, the storage unit 116 stores the first reference reception voltage 1161, the first reception voltage 1162, the second reception voltage 1163, the second reference reception voltage 1164, and the first threshold voltage 1165.

(Sensitivity adjustment of double feed sensor)
Next, the sensitivity adjustment of the double feed sensor 118 used in the automatic document transfer device 112 of the image reading device 110 will be described.

First, the relationship between the drive voltage of the transmission unit 1181 of the double feed sensor 118 and the reception voltage of the reception unit 1182 will be described.
FIG. 7 is a table showing the value of the received voltage with respect to the drive voltage of the double feed sensor, and FIG. 8 is a graph showing the relationship between the drive voltage of the double feed sensor and the received voltage.

As shown in FIG. 7, the reception voltage detected by the reception unit 1182 with the reference paper P interposed therebetween with respect to the drive voltage applied to the transmission unit 1181 of the double feed sensor 118 has a drive voltage of 12 (V). As it increases to ~ 24 (V), it increases to 0.868 (V) to 2.27 (V).

When the relationship between the drive voltage and the reception voltage is represented graphically, as shown in FIG. 8, it can be seen that the reception voltage increases almost proportionally as the drive voltage increases.

On the other hand, as shown in FIG. 7, the reception voltage detected by the reception unit 1182 not interposing the reference paper P is detected at a constant value while the reception voltage remains 6.88 (V) even if the drive voltage changes. It can be seen that the received voltage detected by the receiving unit 1182 exceeds the detectable range (6.88 (V)).

Therefore, the set voltage applied to the transmitting unit 1181 of the double feed sensor 118 has a receiving voltage of 6.88 when the output voltage from the transmitting unit 1181 can be received by the receiving unit 1182 without interposing the reference paper P. (V) Set so that it is as follows.

That is, the set voltage applied to the transmission unit 1181, which is the reference for setting the double feed sensor 118, is adjusted and set so that the reception voltage detected by the reception unit 1182 is 6.88 (V) or less. , Detection by the receiving unit 1182 becomes possible.

As a method of lowering the output level of the double feed sensor 118 from the transmission unit 1181, the number of pulses output from the transmission unit 1181 may be reduced.

(Sensitivity adjustment of the double feed sensor to be adjusted based on the standard double feed sensor)
In the first embodiment, the first reference reception voltage 1161 of the reference double feed sensor 118a, the first reception voltage 1162, the second reception voltage 1163, and the second reference reception voltage of the new double feed sensor 118b whose sensitivity is adjusted. Based on 1164, the threshold voltage setting unit 1112 determines the first threshold voltage 1165, which is the basis for determining the double feed of the new double feed sensor 118b.

FIG. 9 is a table showing the value of the reception voltage detected by the reference double feed sensor of the automatic document transport device according to the first embodiment, and FIG. 10 is a table showing the value of the reception voltage detected by the new double feed sensor to be adjusted. It is a table which shows.

As shown in FIG. 9, in the reference double feed sensor 118a, assuming that the drive voltage applied to the transmission unit 1181a is 12 (V), the first reception voltage 1162 detected by the reception unit 1182a is 3.2 (V). , The second reception voltage 1163 is 1.2 (V).

When a voltage 12 (V) is applied to the transmitting unit 1181a without the reference paper P, the receiving voltage detected by the receiving unit 1182a is overloaded at 5 (V) or more, so the set voltage is 5 (V). Set to 3 (V) below.

In the reference double feed sensor 118a, assuming that the set voltage applied to the transmission unit 1181a is 3 (V), the first reference reception voltage 1161 is 1.5 (V).

(Threshold voltage of reference double feed sensor)
Next, in the reference double feed sensor 118a, the first threshold voltage 1165 of the receiving unit 1182a for determining the double feed of the document is determined.
In the first embodiment, the first threshold voltage 1165 of the reference double feed sensor 118a is calculated by the following equation (1) based on the value of the first reception voltage 1162 and the value of the second reception voltage 1163.
1st threshold voltage (V) = (1st reception voltage + 2nd reception voltage) / 2
= (3.2 + 1.2) / 2 = 2.2 (V) ... (1)
Based on the above, the first threshold voltage 1165 of the reference double feed sensor 118a is determined to be 2.2 (V).

The first reference reception voltage 1161, the first reception voltage 1162, the second reception voltage 1163, and the first threshold voltage 1165 of the reference double feed sensor 118a are stored in the storage unit 116.

(Sensitivity adjustment of new double feed sensor)
The sensitivity of the new double feed sensor 118b is adjusted by adjusting the sensitivity of the reference double feed sensor 118a to the first reference reception voltage 1161, the first reception voltage 1162, the second reception voltage 1163, the first threshold voltage 1165, and the new double feed sensor 118b. 2 Set based on the reference reception voltage 1164.

As shown in FIG. 10, in the new double feed sensor 118b, assuming that the set voltage applied to the transmission unit 1181b is 3 (V), the second reference reception voltage 1164 is 1.3 (V). ..

The first reception voltage (X) of the new double feed sensor 118b is as follows, based on the first reception voltage 1162 of the reference double feed sensor 118a, the first reference reception voltage 1161, and the second reference reception voltage 1164. Calculated by equation (2).
1st reception voltage (X) = 2nd reference reception voltage / 1st reference reception voltage x 1st reception voltage
= 1.3 / 1.5 × 3.2 = 2.77 (V) ・ ・ ・ (2)

The second reception voltage (Y) of the new double feed sensor 118b is as follows, based on the second reception voltage 1163 of the reference double feed sensor 118a, the first reference reception voltage 1161, and the second reference reception voltage 1164. Calculated by equation (3).
Second reception voltage (Y) = second reference reception voltage / first reference reception voltage x second reception voltage
= 1.3 / 1.5 × 1.2 = 1.04 (V) ・ ・ ・ (3)

The threshold voltage (second threshold voltage) of the new double feed sensor 118b is based on the value of the first reception voltage 1162 and the value of the second reception voltage 1163 of the new double feed sensor 118b, and is based on the following equation (4). Calculated by
2nd threshold voltage (V) = (1st reception voltage + 2nd reception voltage) / 2
= (2.77 + 1.04) / 2 = 1.90 (V) ... (4)
Based on the above, the second threshold voltage of the new double feed sensor 118b is determined to be 1.90 (V).

The second threshold voltage of the new double feed sensor 118b is set by the amplification / smoothing circuit 119 so that the received signal level after the amplification process does not exceed the upper limit of the detectable received signal level of the receiving unit 1182b. To.

(Sensitivity adjustment processing of new double feed sensor)
Next, an example of the sensitivity adjustment process of the new double feed sensor 118b in the image reading device 110 according to the first embodiment will be described with reference to the flowchart.

FIG. 11 is a flowchart showing an example of a procedure for sensitivity adjustment processing of a new double feed sensor in the image reading device according to the first embodiment.

In the image reading device 110, as shown in FIG. 11, when the process of adjusting the sensitivity of the newly mounted double feed sensor 118 is started, first, the reference set voltage is set in the transmitting unit 1181a of the new double feed sensor 118b. Is applied, and the second reference receiving voltage is detected by the receiving unit 1182b (step S101).

Then, the first reference reception voltage and the first reception voltage of the reference double feed sensor 118a are acquired from the storage unit 116 of the image reading device 110, and the first reception voltage of the new double feed sensor 118b is calculated (step S103). ..

Then, the first reference reception voltage and the second reception voltage of the reference double feed sensor 118a are acquired from the storage unit 116, and the second reception voltage of the new double feed sensor 118b is calculated (step S105).

Then, the threshold voltage of the new double feed sensor 118b is calculated based on the calculated first reference reception voltage and the second reception voltage of the new double feed sensor 118b (step S107).

Then, the calculated first reception voltage, second reception voltage, and second threshold voltage of the double feed sensor 118b are set, and the sensitivity of the new double feed sensor 118b is adjusted (S109).
In this way, the sensitivity of the new double feed sensor 118b can be adjusted without using the reference paper P.

According to the first embodiment, when the sensitivity of the new double feed sensor 118b is adjusted in the automatic document transport device of the image reading device 110, the reference set voltage of the reference double feed sensor 118a is configured as described above. The first reference reception voltage 1161 based on the reference paper P, the first reception voltage 1162 and the second reception voltage 1163 which are the reception voltages intervening in the reference paper P, and the second reference reception voltage based on the reference set voltage of the new double feed sensor 118b. Since the second threshold voltage for determining the double feed of the document transport of the new double feed sensor 118b is determined based on 1164, the sensitivity can be easily adjusted without using the reference paper P.

Further, in the first embodiment, when the sensitivity of the new double feed sensor 118b is adjusted, the sensitivity can be adjusted while being incorporated in the image reading device 110, so that it is possible to correct the attachment error as well. , The detection accuracy can be improved.

Further, in the first embodiment, when adjusting the sensitivity of the new double feed sensor 118b, the setting information of the reference double feed sensor 118a stored in the storage unit 116 of the image reading device 110 and the new double feed sensor 118b Since the sensitivity of the new double feed sensor 118b is adjusted based on the measured information of the above, it can be adjusted by a serviceman or a user in the market without the need for a special jig. As a result, since adjustments can be made in the market, it is possible to replace individual parts, and it is possible to reduce the cost of replacement parts and the amount of work.

Further, in the first embodiment, when the sensitivity of the new double feed sensor 118b is adjusted, the setting information required for the sensitivity adjustment of the new double feed sensor 118b is stored in the storage unit 116. It is also possible to automatically adjust at the same timing. As a result, by automatically adjusting the double feed sensor 118 on a regular basis, it is possible to correct the deterioration of the double feed sensor 118 over time.

Further, by automatically adjusting the double feed sensor 118 immediately before the paper passing operation starts, the double feed sensor 118 is adjusted in consideration of the installation environment, so that high detection accuracy can always be maintained.

(Second Embodiment)
Next, the second embodiment will be described with reference to the drawings.
The method for adjusting the sensitivity of the double feed sensor according to the second embodiment includes the first reference reception voltage and the first threshold voltage in the setting information of the reference double feed sensor 118a, and the second reference reception voltage of the new double feed sensor 118b. Based on the above, the second threshold voltage of the new double feed sensor 118b is calculated.

In the second embodiment, the second threshold voltage of the new double feed sensor 118b is the value of the second reference reception voltage, the value of the first reference reception voltage, and the reference double feed, as shown in FIGS. 9 and 10. It is calculated by the following equation (5) based on the value of the first threshold voltage of the sensor 118a.
2nd threshold voltage (V) = 2nd reference reception voltage / 1st reference reception voltage x 1st threshold voltage
= 1.3 / 1.5 × 2.2 = 1.90 (V) ... (5)
Based on the above, the second threshold voltage of the new double feed sensor 118b is determined to be 1.90 (V).

(Sensitivity adjustment processing of new double feed sensor)
Next, an example of the sensitivity adjustment process of the new double feed sensor 118b in the image reading device 110 according to the second embodiment will be described with reference to the flowchart.

FIG. 12 is a flowchart showing an example of a procedure for sensitivity adjustment processing of a new double feed sensor in the image reading device according to the second embodiment.

As shown in FIG. 12, in the image reading device 110, when the process of adjusting the sensitivity of the newly mounted double feed sensor 118 is started, first, the reference set voltage is set in the transmitting unit 1181a of the new double feed sensor 118b. Is applied, and the second reference receiving voltage is detected by the receiving unit 1182b (step S201).

Then, the first reference reception voltage of the reference double feed sensor 118a is acquired from the storage unit 116 of the image reading device 110 (step S203).

Then, the first threshold voltage of the reference double feed sensor 118a is acquired from the storage unit 116 (step S205).

Then, based on the detected second reference reception voltage of the new double feed sensor 118b, the first reference reception voltage and the first threshold voltage of the acquired reference double feed sensor 118a, the second threshold value of the new double feed sensor 118b is used. Calculate the voltage (step S207).

Then, the calculated second threshold voltage of the double feed sensor 118b is set, and the sensitivity of the new double feed sensor 118b is adjusted (S209).
In this way, the sensitivity of the new double feed sensor 118b can be easily adjusted without using the reference paper P.

According to the second embodiment, when the sensitivity of the new double feed sensor 118b is adjusted, the first reference reception voltage and the first reference reception voltage of the reference double feed sensor 118a and the first reference double feed sensor 118a are performed according to the equation (5). By calculating the second threshold voltage of the new double feed sensor 118b based on the threshold voltage and the second reference reception voltage of the new double feed sensor 118b, the new double feed sensor 118b can be easily calculated. The threshold voltage of the second threshold voltage can be determined.

When adjusting the sensitivity of the new double feed sensor 118b, the drive voltage of the new double feed sensor 118b may be set.

The drive voltage of the new double feed sensor 118b is based on the first reference reception voltage of the reference double feed sensor 118a, the second reference reception voltage of the new double feed sensor 118b, and the drive voltage of the reference double feed sensor 118a. It can be calculated by the following formula (6).
Drive voltage (V) = 1st reference reception voltage / 2nd reference reception voltage x reference drive voltage ... (6)

As the drive voltage of the new double feed sensor 118b, for example, as shown in FIGS. 9 and 10, the set voltage of the reference double feed sensor 118a and the new double feed sensor 118b is set to 3 (V), and the reference double feed sensor 118a When the reference drive voltage is 12 (V)
Drive voltage (V) = 1.5 / 1.3 x 12 (V)
Will be.

(Third Embodiment)
Next, the third embodiment will be described.
The sensitivity adjusting method of the double feed sensor according to the third embodiment is based on the first reference reception voltage, the first reception voltage, and the second reception voltage of the reference double feed sensor 118a, and the new double feed sensor 118b is the first. 2. The feature is that the threshold voltage of the new double feed sensor 118b is determined based on the table for specifying the threshold voltage of the new double feed sensor 118b corresponding to the value of the reference reception voltage.

FIG. 13 is a table showing an example of a table for determining the threshold voltage of the double feed sensor according to the third embodiment.

In the third embodiment, the threshold voltage in the sensitivity adjustment of the double feed sensor 118 is determined based on the setting table shown in FIG.

In the setting table, as shown in FIG. 13, the threshold voltage of the new double feed sensor 118b is specified according to the second reference reception voltage detected by the receiving unit 1182b of the new double feed sensor 118b. Here, the reference setting voltage applied to the transmitting portion 1181b of the new double feed sensor 118b is set to 3 (V).

According to the setting table, when the second reference reception voltage is 1.1 to 2.0 (V), the threshold voltage is 1.6 to 2.9 (V).

Here, the reference setting voltage corresponding to the setting table is set to 3 (V), but a plurality of reference setting voltages applied to the transmitter 1181b of the new double feed sensor 118b are set, and a plurality of setting tables are set. It may be provided so that the threshold voltage is determined corresponding to a plurality of reference setting voltages.

With the above configuration, according to the third embodiment, when adjusting the sensitivity of the new double feed sensor 118b, the setting table is used according to the second reference reception voltage of the new double feed sensor 118b. Since the threshold voltage of the new double feed sensor 118b is specified, the threshold voltage of the threshold voltage of the new double feed sensor 118b can be easily determined.

As described above, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, that is, the modifications are made as appropriate without departing from the gist of the present invention. Embodiments obtained by combining technical means are also included in the technical scope of the present invention.

10 Image forming device 100, 111 Control unit 110 Image reading device 112 Automatic document transfer device 116 Storage unit 118 Double feed sensor (detection sensor)
118a Reference double feed sensor (detection sensor)
118b New double feed sensor (detection sensor)
119 Amplification / smoothing circuit (electronic circuit that amplifies the received signal)
120 Image processing unit 1111 Reception voltage setting unit 1112 Threshold voltage setting unit 1113 Double feed judgment unit 1171 Reference setting voltage 1172 Drive voltage (detection voltage)
1181, 1181a, 1181b Transmitter 1182, 1182a, 1182b Receiver P Reference paper

Claims (7)

It is a sensitivity adjustment method of a detection sensor that has a transmitter and a receiver and detects paper conveyed by the ultrasonic method.
In the reference detection sensor, the first reference reception voltage detected by the reception unit when the reference setting voltage is applied to the transmission unit,
When a detection voltage is applied to the transmitter, the first reception voltage detected by the receiver when one sheet of reference paper, which is a reference for paper detection, is interposed, and
When a detection voltage is applied to the transmitting unit, a second receiving voltage detected by the receiving unit when at least two sheets of the reference paper are interposed is used.
In addition to,
In the detection sensor to be adjusted for sensitivity, the second reference reception voltage detected by the reception unit when the reference setting voltage is applied to the transmission unit,
Based on
A method for adjusting the sensitivity of a detection sensor, which comprises determining a threshold voltage for determining double feeding of the detection sensor to be adjusted for sensitivity. It is a sensitivity adjustment method of a detection sensor that has a transmitter and a receiver and detects paper conveyed by the ultrasonic method.
In the reference detection sensor, the first reference reception voltage detected by the reception unit when the reference setting voltage is applied to the transmission unit,
The first detection voltage applied to the transmitter and
In addition to,
In the detection sensor to be adjusted for sensitivity, the second reference reception voltage detected by the reception unit when the reference setting voltage is applied to the transmission unit,
Based on
A method for adjusting the sensitivity of a detection sensor, which comprises determining a second detection voltage applied to a transmitting portion of the detection sensor to be adjusted for sensitivity. The detection according to claim 1 or 2, wherein the reference setting voltage is smaller than the detection voltage and is a value that does not exceed the upper limit value that can be detected by the receiving unit of the reference detection sensor. How to adjust the sensitivity of the sensor. Further, an electronic circuit for amplifying the received signal detected by the receiving unit is provided.
The detection according to claim 1 or 2, wherein the received signal level after the amplification process is set by the electronic circuit so as not to exceed the upper limit value of the detectable received signal level of the receiving unit. How to adjust the sensitivity of the sensor. The detection according to claim 1 or 2, wherein the threshold voltage for determining the double feeding of the paper of the detection sensor to be adjusted for sensitivity is determined based on the first reception voltage and the second reception voltage. How to adjust the sensitivity of the sensor. The threshold voltage is based on the first reference reception voltage, the first reception voltage, and the second reception voltage, and corresponds to the value of the second reference reception voltage of the detection sensor to be adjusted for sensitivity. The method for adjusting the sensitivity of a detection sensor according to claim 1, wherein the voltage is determined based on a table for specifying the voltage. The second detection voltage is based on the first reference reception voltage, the first detection voltage, and the second reference reception voltage, and corresponds to the value of the second reference reception voltage for the second detection. The method for adjusting the sensitivity of a detection sensor according to claim 1, wherein the voltage is determined based on a table for specifying the voltage.

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