JPH11316868A - Method for detecting medium remaining in image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect whether a print medium remain in a carrying path or not without being affected by the thickness of the print medium like paper money direct of the carrying path in an image reader. SOLUTION: A sampling and holding signal HLD whose pulse width is wider than that of normal image read is given to a CCD line sensor 16 to read a pixel signal PSG on a glass 11a. The signal PSG is converted to pixel data PDT by an A/D conversion part 20 and is stored in a RAM 24A as line data 24a. Thus, paper money 1 is detected even if the paper money overlap on the glass 11a. Further, line data 23a is masked with mask data 23c corresponding to the position of dirt of the glass 11a, and it is discriminated whether there is a remaining medium or not based on non-masked pixel data PDT. Thus, a remaining medium I is surely detected without being affected by dirt of the carrying path 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type image reading apparatus which irradiates light from the back side of a printing medium such as a bill and detects the intensity of the light radiated from the front side to read a printed image. The present invention relates to a medium remaining detection method for detecting a print medium remaining at a reading position.

[0002]

2. Description of the Related Art FIG. 2 is a schematic configuration diagram of a conventional image reading apparatus. This image reading apparatus reads, for example, images printed on the front and back of a banknote 1 and determines authenticity thereof, and has a transport path 11 for transporting the banknote 1 to be read in a predetermined direction. . A transport section 12 including a guide roller, a stepping motor, and the like for sequentially transporting the banknotes 1 at a predetermined speed is attached to the transport path 11. Also, at a predetermined position in the middle of the transport path 11,
In order to irradiate light from the back of the bill 1 being conveyed,
A transparent glass 11a is fitted. An electric lamp 14 driven by a light source driving unit 13 is disposed below the transport path 11, and the glass 11 a is irradiated with light at an angle of about 45 ° with respect to the transport path 11. Glass 11
a, a lens 15 and a charge-coupled device (hereinafter referred to as “C
A line sensor 16 (referred to as “CD”) is provided.
The image of the bill 1 conveyed on the glass 11a is focused on the light receiving surface of the D line sensor 16.

This image reading apparatus uses a reference clock signal C
A clock generation unit 17 for generating LK is provided, and a CCD control unit 18 is connected to an output side of the clock generation unit 17. The CCD controller 18 receives the reference clock signal C
A sample hold signal HLD and a sampling signal SPL for controlling the operation of the CCD line sensor 16 are generated based on the LK. An analog / digital (hereinafter, referred to as “A / D”) converter 20 is connected to an output side of the CCD line sensor 16 via an amplifier 19, and the output side of the A / D converter 20 is connected to a common bus 21.
It is connected to the. The common bus 21 includes an A / D converter 2
0, a read-only memory (hereinafter, referred to as “ROM”) 22, and a readable / writable memory (hereinafter, referred to as “RAM”)
) 23 and a central processing unit (hereinafter, referred to as “CPU”) 24.

[0004] The ROM 22 is a memory that stores a program for defining the processing procedure of the image reading apparatus and fixed data necessary for the processing. The RAM 23 stores line data 23a, which is one line of pixel data PDT converted by the A / D converter 20, and pixel data PD of a plurality of lines.
This is a memory for storing image data 23b and the like of the banknote 1 read as T. The CPU 24 is supplied with a start signal STA for instructing an operation start from the outside, a sample hold signal HLD and a sampling signal SPL from the CCD control unit 18, a transport control signal CCS for the transport unit 12, and a light source drive unit 13. The light source control signal LCS is output. Also, CP
U24 is the pixel data PDT converted by the A / D converter 20 based on the program stored in the ROM 22.
Is R as the line data 23a and the image data 23b.
AM 23 and the line data 23a
And outputs a medium residual signal RES by determining whether or not the bill 1 remains. Furthermore,
The CPU 24 has a function of determining the authenticity of the bill 1 based on the image data 23b and outputting an image detection signal DET.

In such an image reading apparatus, when a start signal STA is given, the operation of the CPU 24 starts,
Based on the program stored in the ROM 22, first, a medium remaining detection process for checking whether or not the bill 1 remains on the portion of the glass 11a that is the reading position on the transport path 11 is started. In the medium residual detection process, first, the light source control signal LCS is set to ON,
The electric light 14 is turned on by the light source driving unit 13. Light 1
The light radiated from 4 irradiates the glass 11a of the transport path 11 obliquely. Therefore, if the banknote 1 does not exist on the glass 11a, the light does not enter the CCD line sensor 16. Therefore, the light level on the light receiving surface of the CCD line sensor 16 becomes the black level. If the bill 1 remains on the glass 11a, the light irradiated from the back surface passes through the bill 1 and is radiated as scattered light from the front surface. The scattered light emitted upward is condensed by the lens 15 and focuses on the light receiving surface of the CCD line sensor 16.

The light level on the light receiving surface of the CCD line sensor 16 is held by a sample hold signal HLD, and is sequentially read out as an analog voltage pixel signal PSG one pixel at a time in accordance with the sampling signal SPL. / D conversion unit 20. Pixel data PDT converted to digital values by A / D converter 20
Is read by the CPU 24 and stored in the RAM 23 as line data 23a. When the pixel data PDT for one line is stored, the line data 23a is read by the CPU 24, and the number of pixel data PDT having a predetermined value or more is counted. If the counted number of the pixel data PDT is equal to or more than a certain number, it is determined that the banknote 1 remains, and the medium residual signal RES is output. By such a medium remaining detection process, the banknote 1
If it is determined that does not remain, the image reading process is started next.

At the start of the image reading process, the transport control signal CCS output from the CPU 24 is turned on, and the transport of the bill 1 to be read is started. Conveyed banknote 1
Reaches the glass 11a of the transport path 11, the bill 1
The light emitted through the surface of the CCD is detected by the CCD line sensor 16 and output as a plurality of pixel signals PSG constituting one line. The pixel signal PSG is converted into pixel data P by the A / D converter 20 in the same manner as in the residual medium detection processing.
The data is converted to DT and stored in the RAM 23 as image data 23b. When the image data 23b of one banknote 1 is stored, the CPU 24 reads the image data 23b, determines the authenticity of the banknote 1, and outputs the determination result as an image detection signal DET.

[0008]

However, the conventional image reading apparatus has the following problems. For example,
When the print medium such as the remaining banknote 1 is thick paper, or when a plurality of print mediums are left over, the amount of transmitted light is reduced and the level of the pixel signal PSG is reduced. In such a case, if dirt or the like adheres to the surface of the glass 11a of the transport path 11, the amount of light incident on the CCD line sensor 16 is further reduced, and the state becomes the same as when there is no print medium. However, there has been a problem that the detection accuracy of the residual medium is reduced. The present invention solves the problems of the prior art described above, and is not affected by the thickness of the print medium, the contamination of the transport path 11, and the like, and is capable of reliably detecting the presence or absence of a remaining print medium. It is an object of the present invention to provide a method for detecting a residual medium.

[0009]

According to a first aspect of the present invention, a printing medium to be read is conveyed through a predetermined conveying path, and the back side of the medium is read from a first direction. While irradiating light, the intensity of light transmitted through the print medium and emitted from the surface thereof in a second direction different from the first direction is detected for each pixel by CCDs arranged linearly. A method for detecting a medium remaining in an image reading apparatus that reads an image on the print medium is performed by the following processing. First, light is irradiated from the first direction without transporting the print medium to be read to the transport path,
A detection process of detecting the light intensity in the direction of the above by the CCD, and comparing the light intensity of each pixel detected by the detection process with a first reference value, and determining the number of pixels exceeding the first reference value. And a first determination process for determining the presence or absence of a print medium remaining on the transport path based on the above.

Next, when it is determined by the first determination processing that there is no print medium, the light intensity of the pixels not masked by the determination mask data among the pixels detected by the detection processing is reduced by the first determination processing. 2nd smaller than the reference value of 1
And a second determination process for determining whether there is a print medium remaining on the conveyance path based on the number of pixels exceeding the second reference value. Further, when it is determined by the second determination process that there is no print medium, a mask data update process of updating the determination mask data based on the light intensity of each pixel detected in the detection process is performed. Do.

According to the first aspect of the present invention, since the method for detecting a residual medium is configured as described above, the following operation is performed. The detection processing detects the light intensity in a state where the print medium is not conveyed, and the first determination processing determines the presence or absence of the remaining print medium based on the detected light intensity, and determines that the print medium is present. Then, the detection of the remaining medium ends.
If it is determined that there is no print medium in the first determination process, the second determination process masks the data for each pixel with the mask data for determination, and determines the presence or absence of the remaining print medium based on the unmasked data. Is determined, the medium residual detection ends. As a result of the second determination process, when it is determined that there is no residual, a mask data update process of updating the determination mask data based on the light intensity of each pixel detected in the detection process is performed, and the medium remaining Detection ends.

According to a second aspect of the present invention, a method for detecting a remaining medium in an image reading apparatus similar to the first aspect of the invention is performed by the following processing. First, light is irradiated from the first direction without transporting the print medium to be read to the transport path, and a read pulse having a first pulse width is given to the CCD, and light in the second direction is emitted. A first detection process of reading and detecting the intensity of light, and comparing the intensity of light of each pixel detected in the first detection process with a first reference value, and determining whether a pixel exceeds the first reference value. A first determination process of determining whether there is a print medium remaining on the conveyance path based on the number of print media. Next, when it is determined by the first determination process that there is no print medium, light is irradiated from the first direction without transporting the print medium to be read to the transport path, and A second pulse width wider than the first pulse width.
And performs a second detection process of reading and detecting the intensity of light in the second direction. Further, the light intensity of each pixel detected in the second detection processing is compared with a second reference value, and the print medium remaining on the transport path is determined based on the number of pixels exceeding the second reference value. A second determination process for determining the presence or absence of is performed.

According to the second aspect, the following operation is performed. By the first detection processing, a reading pulse having a first pulse width is given to the CCD in a state where the print medium is not conveyed, and the light intensity is detected. By the first determination processing,
The presence or absence of the remaining print medium is determined based on the detected light intensity, and if it is determined that the print medium remains, the medium residual detection ends. If it is determined that the print medium is not present in the first determination processing, the second detection processing is performed in a state where the print medium is not conveyed.
A read pulse having a wide second pulse width is applied to D, and the light intensity is detected. Then, by the second determination process, the presence or absence of the remaining print medium is finally determined based on the detected light intensity, and the medium residual detection ends.

According to a third aspect of the present invention, a method for detecting a medium remaining in an image reading apparatus similar to the first aspect of the invention is performed by the following processing. First, a first detection process, a first determination process, and a second detection process similar to those of the second invention are performed, and then a determination is made among the pixels detected in the second detection process. Comparing the light intensity of the pixels that are not masked by the mask data with the second reference value, and determining the presence or absence of a print medium remaining on the transport path based on the number of pixels exceeding the second reference value. Perform determination processing. When it is determined that there is no print medium in the second determination process, the mask data for determination is updated based on the light intensity of each pixel detected in the first or second detection process. Perform a mask data update process.

According to the third aspect, the following operation is performed. By the first detection processing, a reading pulse having a first pulse width is given to the CCD in a state where the print medium is not conveyed, and the light intensity is detected. By the first determination processing,
The presence or absence of the remaining print medium is determined based on the detected light intensity, and if it is determined that the print medium remains, the medium residual detection ends. If it is determined that the print medium is not present in the first determination processing, the second detection processing is performed in a state where the print medium is not conveyed.
A read pulse having a wide second pulse width is applied to D, and the light intensity is detected. Then, in the second determination process, the data for each pixel detected in the second detection process is masked with the mask data for determination, and the presence or absence of the remaining print medium is determined based on the unmasked data. Then, the detection of the remaining medium ends. As a result of the second determination process, when it is determined that there is no residual, a mask data update process of updating the determination mask data based on the light intensity of each pixel detected in the detection process is performed, and the medium remaining Detection ends.

According to a fourth aspect of the present invention, the printing medium to be read is conveyed through a predetermined conveyance path, and the back surface of the printing medium is irradiated with light from a first direction. The intensity of light emitted in a second direction different from the direction of
A method for detecting a medium remaining in an image reading apparatus that detects an image on the printing medium by detecting each pixel by D and recognizes an image based on a fixed percentage of the read pixels by the following processing. Is going. First, light is irradiated from the first direction without transporting the print medium to be read to the transport path, and the intensity of light in the second direction is detected by the CCD at the predetermined resolution for each pixel. And comparing the light intensity of each pixel detected in the detection processing with a reference value, and determining whether there is a print medium remaining on the transport path based on the number of pixels exceeding the reference value. Is performed.

According to the fourth aspect, the following operation is performed. By the detection processing, the intensity of light in a state where the print medium is not conveyed is detected, and pixels having a predetermined resolution are obtained. In the determination process, the presence or absence of the remaining print medium is determined based on the detected light intensity of each pixel. Fifth
According to the invention, a medium remaining detection method in an image reading apparatus similar to the fourth invention is performed by the following processing. First,
The same detection processing as in the fourth invention is performed, and further, the light intensity of each pixel detected in the detection processing is compared with a first reference value, and based on the number of pixels exceeding the first reference value. A first determination process for determining whether there is a print medium remaining on the transport path is performed. Next, when it is determined by the first determination process that there is no print medium, the light intensity of a pixel not masked by the determination mask data among the pixels detected by the CCD is determined by the first reference value. A second reference value smaller than the second reference value, and performing a second determination process of determining the presence or absence of a print medium remaining on the conveyance path based on the number of pixels exceeding the second reference value. Further, when it is determined by the second determination process that there is no print medium, a mask data update process of updating the determination mask data based on the light intensity of each pixel detected in the detection process is performed. Do.

According to the fifth aspect, the following operation is performed. By the detection processing, the intensity of light in a state where the print medium is not conveyed is detected, and pixels having a predetermined resolution are obtained. In the first determination process, the presence or absence of the remaining print medium is determined based on the detected light intensity of each pixel,
If it is determined that the medium is present, the medium remaining detection ends. If it is determined that there is no result in the first determination process, the second determination process
The data for each pixel is masked with the mask data for determination, and the presence or absence of the remaining print medium is determined based on the unmasked data. If it is determined that the print medium remains, the medium residual detection ends. As a result of the second determination process, when it is determined that there is no residual, a mask data update process of updating the determination mask data based on the light intensity of each pixel detected in the detection process is performed, and the medium remaining Detection ends.

In the sixth invention, the detection processing in the first to fifth inventions is performed by irradiating light from the first direction without transporting the print medium to be read to the transport path. Is detected a plurality of times by the charge-coupled device, and an average value of the light intensity of each pixel in the plurality of detections is used as a detection result. According to the sixth aspect, the following detection processing is performed. In a state in which the print medium is not conveyed, the light intensity of each pixel is detected a plurality of times by the CCD, an average value of the light intensity of each pixel is calculated and output as a detection result.

[0020]

FIG. 1 is a schematic block diagram of an image reading apparatus used in a residual medium detection method according to an embodiment of the present invention. The elements common to the elements in the conventional image reading apparatus of FIG. Are denoted by common symbols. This image reading apparatus, like the image reading apparatus in FIG. 2, reads images printed on both front and back sides of a printing medium (for example, banknote) 1 at a time to judge the authenticity of the images. It has a transport path 11 for transporting the banknote 1 in a predetermined direction. A transport section 12 including a guide roller, a stepping motor, and the like for sequentially transporting the banknotes 1 at a predetermined speed is attached to the transport path 11. At a predetermined position in the middle of the transport path 11, the transported banknote 1
A transparent glass 11a is fitted to irradiate light from the back of the device. An electric lamp 14 driven by a light source driving unit 13 is disposed below the transport path 11.
The glass 11a is irradiated with light at an angle of about 45 ° to the glass 11a. A lens 15 and a CCD line sensor 16 are arranged directly above the glass 11a.
The image of the bill 1 conveyed onto the glass 11a is focused on the light receiving surface of the line sensor 16.

The CCD line sensor 16 is, for example, 200
The CCDs are arranged in one row, and accumulate charges corresponding to the intensity of light applied to each CCD in accordance with the pulse width of a read pulse (for example, a sample hold signal) HLD. . Further, a voltage corresponding to the charge stored in each CCD is sequentially shifted in synchronization with the sampling signal SPL, and is output as a pixel signal PSG. This image reading apparatus has a clock generator 17 for generating a reference clock signal CLK, and an output side of the clock generator 17 has a CCD controller 18
A is connected. The CCD control unit 18A includes a sample and hold signal HLD and a sampling signal S for controlling the operation of the CCD line sensor 16 based on the reference clock signal CLK, similarly to the CCD control unit 18 in FIG.
And a pulse control signal PCS
Thereby, the pulse width of the sample hold signal HLD can be controlled. That is, the pulse control signal PCS
When is off, normal pulse width (for example, 10 μs)
Is generated, and when the pulse control signal PCS is on, a sample hold signal HLD having a pulse width (for example, 20 μs) wider than a normal pulse width is generated.

An A / D converter 20 is connected to an output side of the CCD line sensor 16 via an amplifier 19.
The A / D converter 20 outputs, for example, an 8-bit digital value (that is, 0 to 0) in accordance with the voltage of the input pixel signal PSG.
255) is output as pixel data PDT. The output side of the A / D converter 20 is connected to the common bus 21. The ROM 22A, the RAM 23A, and the CPU 24A are connected to the common bus 21 in addition to the A / D converter 20. The ROM 22A is a memory that stores a program that defines the processing procedure of the image reading apparatus and fixed data necessary for the processing. RAM 23A is A
The line data 23a, which is 200 pieces of pixel data PDT for one line converted by the / D conversion unit 20, and the image data 23b of the banknote 1 composed of a plurality of lines of line data 23a are stored. Further, RAM 23A
Stores the mask data 23c for masking a part of the pixel data PDT in the line data 23a at the time of the medium remaining determination.

The CPU 24A is supplied with a sample hold signal HLD and a sampling signal SPL from the CCD controller 18 for the timing of reading the pixel data PDT from the start signal STA for externally instructing the start of the operation, and also provides a transport unit. 12 for the transport control signal C
It outputs a CS and a light source control signal LCS to the light source drive unit 14. Further, the CPU 24A
It outputs a pulse control signal PCS to the CD control unit 18A. Also, the CPU 24A has a ROM
The pixel data PDT converted by the A / D conversion unit 20 based on the program stored in the RAM 22A is stored in the RAM 23A as line data 23a and image data 23b, and the line data 23a and the mask data 2 are stored in the RAM 23A.
It has a function of determining whether or not the bill 1 remains on the transport path 11 with reference to 3c and outputting a medium residual signal RES as a result of the determination. Further, the CPU 24A sets the RO
According to the program stored in the M22A, it has a function of determining the authenticity of the banknote 1 based on the image data 23b and outputting the determination result as an image detection signal DET.

Next, the operation of the image reading apparatus of FIG. 1 will be described. When the activation signal STA is given to the image reading apparatus, the operation of the CPU 24A is started, and based on the program stored in the ROM 22A, the bill 1 is first placed on the glass 11a which is the reading position of the transport path 11. The medium remaining detection process for checking whether or not the medium remains is started.

FIG. 3 is a flowchart showing the procedure of the medium residual detection process according to the embodiment of the present invention. When the medium residual detection process is started, in step S1 of FIG. 3, operating conditions are set, the light source control signal LCS is turned on, the pulse control signal PCS and the transport control signal CCS are turned off,
Each is set. Thereby, the electric lamp 14 is turned on by the light source driving unit 13. Since the pulse control signal PCS is turned off, the sample hold signal HLD supplied from the CCD control unit 18 to the CCD line sensor 16 is used.
Is the same pulse width as in normal image reading (for example, 10
μs). Also, the transport of the banknote 1 is not started because the transport control signal CCS is off. After step S1, the process proceeds to first detection processing of steps S2 to S4.

In step S2, reading of one line of pixel data PDT is performed as follows. First, a sample hold signal HLD having a pulse width of 10 μs is supplied from the CCD controller 18 to the CCD line sensor 16. Thereby, charges corresponding to the intensity of light condensed on the light receiving surface of the CCD line sensor 16 from the surface of the glass 11a of the transport path 11 through the lens 15 are held by the 200 CCDs of the CCD line sensor 16. You. Next, 200 sampling signals SPL are supplied to the CCD line sensor 16. This allows 200 CCs
The pixel signal PSG corresponding to the charge of D is sequentially read from the CCD line sensor 16 and amplified by the amplifying unit 19 so that A / A
The data is input to the D conversion unit 20. In the A / D converter 20, the 200 pixel signals PSG are converted into 200 pixel data PDT having 256 gradations, and the common bus 21.
Is read by the CPU 24A via the.

In step S3, it is determined whether the reading of the pixel data PDT for one line has been performed n times (for example, n = 4). If the reading has not been completed n times, the process returns to step S2, and if completed, the process proceeds to step S4. In step S4, the average value of each pixel of the pixel data PDT obtained by four readings is calculated. Then, the calculated 200 pixel data PT
D is stored in the RAM 23A as line data 23a. After step S4, the process proceeds to a first determination process in step S5.

In step S5, the remaining bill 1 is determined as follows based on the value of the line data 23a obtained in step S4. That is, the light 14
Is emitted from the diagonal direction to the glass 11a of the transport path 11, so that the bill 1 is placed on the glass 11a.
Does not exist, the light of the electric lamp 14 does not enter the CCD line sensor 16. Therefore, the light level on the light receiving surface of the CCD line sensor 16 becomes a black level, and
All the values of the pixel data PDT should be 0. If the banknote 1 remains on the glass 11a, light emitted from the back surface passes through the banknote 1 and is emitted from the front surface of the banknote 1 as scattered light. The scattered light radiated upward is collected by the lens 15 and
Focus on the light receiving surface of the D line sensor 16. As a result, the values of the pixel data PDT do not become all 0, but become various values according to the printing of the banknote 1. Therefore, of the 200 pixel data PDT of the line data 23a, the value is the first reference value REF1 (for example, REF1 = 10).
Is counted, and if the number CNT1 exceeds, for example, 20, it is determined that the banknote 1 remains. If it is determined in step S5 that the banknote 1 remains, the medium remaining detection process ends. On the other hand, when it is not determined that the banknote 1 remains based on the determination criterion in step S5, the process proceeds to the second detection processing in steps S6 to S9.

In the second detection process, for example, when a plurality of banknotes 1 remain in a pile, the light transmitted through these banknotes 1 becomes weak, and the value of each pixel data PDT of the obtained line data 23a is reduced. Is smaller and does not satisfy the determination criterion of step S5. In step S6, the pulse control signal PCS is set on. As a result, the sample hold signal HLD supplied from the CCD controller 18 to the CCD line sensor 16 is switched to a pulse width of 20 μs, which is wider than that during normal image reading, and step S7 is performed.
Proceed to. In step S7, reading of one line of pixel data PDT is performed in the same manner as in step S2. However, since the pulse width of the sample hold signal HLD applied to the CCD line sensor 16 is 20 μs, the pixel signals PSG sequentially read from the CCD line sensor 16 in synchronization with the sampling signal SPL.
Has a higher voltage than in step S2. The 200 pixel signals PSG are amplified by the amplifier 19 and input to the A / D converter 20. Pixel signal PSG
Are the 200 pixel data P in the A / D converter 20.
It is converted into DT and read by the CPU 24A via the common bus 21.

In step S8, it is determined whether or not reading of the pixel data PDT for one line has been performed n times. If the reading of n times has not been completed, step S7 is performed.
The process returns to step S9 if completed. In step S9, pixel data P obtained by four readings
An average value of DT for each pixel is calculated. Then, the calculated 200 pieces of pixel data PTD are stored in the RAM 23A as the line data 23a. After step S9, the process proceeds to the second determination process of steps S10 to S11.
In step S10, a mask process of deleting a part of the pixel data PDT of the line data 23a from the determination target is performed by the mask data 23c in the RAM 23A. That is, the mask data 23c includes the pixel data PDT.
This is data for determining whether or not each pixel is to be determined for each determination. For example, the pixel data PDT at a position corresponding to dirt attached to the glass 11a of the transport path 11 is excluded from the determination target. is there. The mask data 23c is
Initially, all the pixel data PDT are set to be determined, and as will be described later, are repeatedly updated and stored while the medium residual detection processing is repeatedly executed.

In step S11, step S10
Based on the value of the line data 23a that has not been masked, the remaining banknote 1 is determined as follows. First, 200 pixel data PDT of the line data 23a
Of the pixel data PDT that is not masked is
The number CNT2 of the number exceeding the second reference value REF2 (for example, REF2 = 8) is counted, and this number C
If NT2 exceeds, for example, 20, it is determined that the banknote 1 remains. If it is determined in step S11 that the banknote 1 remains, the medium remaining detection process ends. If the number CNT2 is 20 or less, it is determined that the banknote 1 does not remain, and the process proceeds to the mask data updating process in step S12. In step S12, among the 200 pixel data PDT of the line data 23a obtained in step S4 or S9, the value corresponding to the one exceeding the third reference value REF3 (for example, REF3 = 15) corresponds. The position of the pixel is stored as mask data 23c for the next medium remaining detection process. By the end of step S12, the medium remaining detection process ends.

As a result of the medium residual detection processing, when it is determined that there is a residual medium, a medium residual signal RES is output from the CPU 24A, and a display or the like is displayed to prompt the operator to remove the residual medium. Will be On the other hand, when it is determined that there is no remaining medium,
Subsequently, the CPU 24A reads the image reading processing program stored in the ROM 22A, and starts reading processing of the bill 1 to be read.

As described above, the medium residual detection processing of this embodiment has the following advantages (1) to (4). (1) Steps S2 to S4 and steps S7 to S9
In the detection process, the pixel data PDT for one line
Are read n times, and the average value is calculated to obtain the line data 23a. This allows
Line data 23a due to electrical noise or the like during reading
The effect of the error can be reduced, and highly accurate detection of the residual medium can be performed. (2) In step S6, a sample hold signal HLD having a wider pulse width than that in normal image reading is set, and in steps S7 and S8, the pixel signal PSG is detected using the sample hold signal HLD. Even if a plurality of banknotes 1 remain in an overlapping state, it can be detected.

(3) In step S10, the pixel data PDT at the reading position where dirt or the like is present is deleted from the pixels to be determined for residual detection, so that the pixel data PDT is not affected by dirt or the like on the transport path 11. Thus, it is possible to detect the residual medium with high accuracy. (4) In step S12, since the mask data 23c is updated and stored based on the latest line data 23a, the latest state of the transfer path 11, such as contamination, can be reflected in the detection of the remaining medium. There is an advantage.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (a) to (f). (A) Steps S2 to S4 and steps S7 to S9
Then, the pixel data PDT for one line is n times (for example,
(4 times), and the average value is used as the line data 23a. However, if there is no possibility of noise or the like, the value may be read only once and the value may be used as the line data 23a. (B) In steps S6 to S9, the line data 23a is read again using the sample hold signal HLD having a wide pulse width. However, these steps S6 to S9 are omitted, and the line obtained in step S4 is omitted. The mask processing in step S10 may be performed using the data 23a. (C) When there is no possibility that dirt or the like adheres to the glass 11a, the mask processing in step S10 and the step S10
Twelve mask data update processes can be omitted.

(D) This image reading apparatus performs the residual medium detection processing at the same resolution of 200 pixels as the image reading processing. For example, a CCD line sensor having a resolution of 400 pixels is used and the residual medium detection processing is performed. Media detection processing is 4
The image reading may be performed at a resolution of 00 pixels, and the image reading processing may be performed using every other 200 pixels. This enables highly accurate residual medium detection processing. (E) The configuration of the image reading device is not limited to FIG.
The present invention can be applied to any image reading apparatus as long as it is a transmission type image reading apparatus using a D-line sensor. (F) CCD line sensor 16 in the description of the embodiment
Are not limited to numerical values such as the number of pixels, the reference value REF1, and the like, and the pulse width of the sample-and-hold signal HLD.

[0037]

As described above in detail, according to the first aspect, the data of each pixel is masked by the mask data for determination, and the presence or absence of the remaining print medium is determined based on the unmasked data. Since the second determination processing is provided, the residual medium can be detected without being affected by dirt or the like by masking dirt or the like on the transport path. According to the second aspect, the second detection processing is provided for detecting the print medium with a read pulse having a wider pulse width when the medium is not detected by the first detection processing. As a result, it is possible to detect the print medium remaining in an overlapped state. According to the third aspect, the second detection processing for detecting the print medium with a read pulse having a wider pulse width than the first detection processing, and masking the data for each pixel with the mask data for determination and not masking And a second determination process for determining the presence or absence of the remaining print medium based on the data. As a result, it is possible to reliably detect the print medium remaining in an overlapped state without being affected by the contamination of the transport path.

According to the fourth aspect, the detection processing and the determination processing for detecting and determining the remaining medium with a higher resolution than the resolution at the time of reading the image are provided. As a result, the remaining print medium can be detected with high accuracy. According to the fifth aspect, a detection process of detecting a remaining medium at a resolution higher than the resolution at the time of reading an image, masking data for each pixel with mask data for determination, and determining a remaining medium based on unmasked data. And a second determination process for determining the presence or absence of a print medium to be performed. As a result, the remaining print medium can be detected with high accuracy without being affected by contamination of the transport path. According to the sixth aspect, the light intensity of each pixel is detected a plurality of times, and the determination of the remaining print medium is performed based on the average value of the light intensity of each pixel. This can prevent a detection error due to noise or the like at the time of medium detection.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus used in a residual medium detection method according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional image reading apparatus.

FIG. 3 is a flowchart illustrating a procedure of a medium remaining detection process according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Banknote 11 Conveyance path 11a Glass 14 Electric light 16 CCD line sensor 18 CCD control part 20 A / D conversion part 22A ROM 23A RAM 23a Line data 23b Image data 23c Mask data 24A CPU

Claims (6)

[Claims] 1. A printing medium to be read is transported through a predetermined transport path, and the back surface is irradiated with light from a first direction. Detecting the intensity of light emitted in the different second direction for each pixel by a charge-coupled device arranged linearly;
In an image reading apparatus that reads an image on the print medium, the transfer path irradiates light from the first direction without transporting the print medium to be read, and reduces the intensity of light in the second direction. A detecting process for detecting by the charge-coupled device, and comparing a light intensity of each pixel detected in the detecting process with a first reference value, and comparing the light intensity on the transport path based on the number of pixels exceeding the first reference value. First determination processing for determining the presence or absence of a print medium remaining in the image data; and, when the first determination processing determines that there is no print medium, mask data for determination among pixels detected in the detection processing. Comparing the light intensity of the pixel not masked by the second reference value smaller than the first reference value;
A second determination process for determining whether there is a print medium remaining on the conveyance path based on the number of pixels exceeding the second reference value; and a case where the second determination process determines that there is no print medium. Performing a mask data update process of updating the mask data for determination based on the light intensity of each pixel detected in the detection process. 2. A printing medium to be read is conveyed through a predetermined conveyance path, and the back surface is irradiated with light from a first direction. Detecting the intensity of light emitted in the different second direction for each pixel by a charge-coupled device arranged linearly;
An image reading apparatus that reads an image on the print medium, irradiating light from the first direction without transporting the print medium to be read to the transport path, and applying a first pulse width to the charge-coupled device. A first detection process for reading and detecting the intensity of light in the second direction, and detecting the intensity of light for each pixel detected in the first detection process as a first reference value. A first determination process of determining whether there is a print medium remaining on the transport path based on the number of pixels exceeding the first reference value, and determining that there is no print medium by the first determination process In this case, light is irradiated from the first direction without transporting the print medium to be read to the transport path, and a second pulse wider than the first pulse width is applied to the charge-coupled device. Give a read pulse of width A second detection process for reading and detecting the intensity of light in a second direction; and comparing the intensity of light for each pixel detected in the second detection process with a second reference value. Performing a second determination process of determining whether there is a print medium remaining on the conveyance path based on the number of pixels exceeding the reference value of (a). 3. A printing medium to be read is conveyed through a predetermined conveyance path, and the back surface is irradiated with light from a first direction. Detecting the intensity of light emitted in the different second direction for each pixel by a charge-coupled device arranged linearly;
An image reading apparatus that reads an image on the print medium, irradiating light from the first direction without transporting the print medium to be read to the transport path, and applying a first pulse width to the charge-coupled device. A first detection process for reading and detecting the intensity of light in the second direction, and detecting the intensity of light for each pixel detected in the first detection process as a first reference value. A first determination process of determining whether there is a print medium remaining on the transport path based on the number of pixels exceeding the first reference value, and determining that there is no print medium by the first determination process In this case, light is irradiated from the first direction without transporting the print medium to be read to the transport path, and a second pulse wider than the first pulse width is applied to the charge-coupled device. Give a read pulse of width A second detecting process of detecting and reading the intensity of the light in the second direction, the intensity of light of the pixel that is not masked by the determined mask data among the pixels detected by the second detection processing second
And a second determination process of determining whether there is a print medium remaining on the conveyance path based on the number of pixels exceeding the second reference value. When it is determined that there is no mask data, a mask data update process of updating the mask data for determination based on the light intensity of each pixel detected in the first or second detection process is performed. Medium detection method in an image reading apparatus. 4. A printing medium to be read is conveyed through a predetermined conveyance path, and the back surface is irradiated with light from a first direction. Reading the image on the print medium by detecting the intensity of the light emitted in the different second direction for each pixel by a charge-coupled device having a predetermined resolution linearly arranged,
In an image reading device that recognizes an image based on a fixed percentage of pixels among the read pixels, irradiating light from the first direction without transporting the print medium to be read to the transport path, A detection process for detecting the intensity of light in a second direction by the charge-coupled device at the predetermined resolution for each pixel; comparing the intensity of light of each pixel detected in the detection process with a reference value; Determining a presence or absence of a print medium remaining on the conveyance path based on the number of pixels exceeding the value. 5. A printing medium to be read is conveyed through a predetermined conveyance path, and the back surface is irradiated with light from a first direction. Reading the image on the print medium by detecting the intensity of the light emitted in the different second direction for each pixel by a charge-coupled device having a predetermined resolution linearly arranged,
In an image reading device that recognizes an image based on a fixed percentage of pixels among the read pixels, irradiating light from the first direction without transporting the print medium to be read to the transport path, A detection process of detecting the intensity of light in a second direction by the charge-coupled device at the predetermined resolution for each pixel, and comparing the intensity of light of each pixel detected in the detection process with a first reference value. A first determination process of determining whether there is a print medium remaining on the conveyance path based on the number of pixels exceeding the first reference value; and a case where the first determination process determines that there is no print medium. Comparing the light intensity of a pixel not masked by the mask data for determination among the pixels detected by the charge-coupled device with a second reference value smaller than the first reference value; Based on the number of pixels A second determination process for determining the presence or absence of a print medium remaining on the transport path, and for each pixel detected in the detection process when it is determined that there is no print medium in the second determination process. Performing a mask data update process of updating the mask data for determination based on light intensity. 6. The detection process according to claim 1, 4 or 5, or the first and second detection processes according to claim 2 or 3, wherein the first and second detection processes are performed without transporting the print medium to be read to the transport path. Irradiating light from the first direction, the second
Characterized by detecting the intensity of light in the direction of a plurality of times by the charge-coupled device, and using the average value of the intensity of light for each pixel in the plurality of detections as a detection result. Method.