JP4597683B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus that detects the presence / absence of double feeding and / or paper type in a conveyance path for conveying a recording member. is there.

  2. Description of the Related Art Conventionally, there has been known an image forming apparatus including a detection unit that detects whether or not a transfer sheet as a recording member in a paper conveyance path is double-fed (for example, Patent Document 1).

  In addition, the light emitted from the light emitting means is applied to the transfer paper as a recording member in the paper conveyance path, and the amount of light transmitted through the transfer paper is detected by the light receiving means, and the light in the paper conveyance path is detected based on the light quantity. Conventionally, an image forming apparatus provided with a detecting means for detecting the presence / absence of double feeding and a paper type is also known. This detecting means is disposed in the vicinity of the registration roller, and detects the double feeding of the transfer paper and the paper type when the transfer paper is stopped by hitting the registration roller.

  The presence or absence of double feeding is performed as follows. That is, since the amount of transmitted light that has passed through a plurality of transfer papers is less than the amount of transmitted light that has passed through one sheet of transfer paper, this detection means has an output voltage value from a light receiving means that detects the amount of transmitted light, and The presence or absence of double feed can be detected by comparing with a preset reference value.

  The paper type is detected as follows. That is, a thick transfer paper has a smaller amount of light transmitted through the transfer paper than a thin transfer paper. In addition, a highly transparent transfer paper such as OHP increases the amount of light transmitted through the transfer paper as compared to plain paper. As described above, since the amount of light transmitted through the transfer paper differs depending on the paper type, the output voltage value from the light receiving means for each paper type is stored in advance. Then, by comparing the output voltage obtained by the light receiving means from the amount of light transmitted through the transfer paper in the transport path and the output voltage of each paper type stored in advance, the paper type of the transfer paper in the transport path Can be determined.

Japanese Patent Laid-Open No. 62-161655

  Usually, the detecting means has the light emitting means and the light receiving means arranged so that the optical path of the light emitted toward the light receiving means is orthogonal to the transfer paper in the transport path. However, when the transfer paper waved up and down or curled up and down is conveyed in the optical path of the light irradiated toward the light receiving means, the optical path of the light irradiated toward the light receiving means and the transfer paper are orthogonal to each other. No longer. As a result, the distance passing through the transfer paper is longer than when the optical path of the light and the transfer paper are orthogonal, and the amount of light passing through the transfer paper is orthogonal to the optical path of the light and the transfer paper. Compared to when it is reduced. As a result, the output voltage value decreases compared to when the optical path of the light and the transfer paper are orthogonal to each other, and it is falsely detected that there is a double feed, or it is falsely detected that the paper type is thick. There was a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to accurately detect the presence / absence of double feeding and the type of paper even if the transfer paper undulates or curls up and down. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

In order to achieve the above object, the invention of claim 1 comprises: a light emitting means for irradiating light toward the conveying path; and a light receiving means for detecting light from the light emitting means that has passed through the recording member in the conveying path. In the image forming apparatus for detecting the presence / absence of double feeding of the recording member in the conveyance path and / or the paper type based on the output voltage from the light receiving means and the reference data, the recording member is abutted against the recording member. And a pair of guide plates provided on the upstream side in the transport direction from the registration rollers, and a plurality of portions in the vicinity of a portion where the recording member bends and abuts against the guide plate through the transmitted light transmitted from the recording member. detected at the location, No double feed of the recording member in the highest output voltage and the conveying path on the basis of the reference data of the output voltage value obtained when detecting the light transmitted through from the recording member of the sensing portion It is characterized in that to detect the free and / or paper type.
Further, the invention of claim 2 comprises light emitting means for irradiating light toward the transport path, and light receiving means for detecting light from the light emitting means that has passed through the recording member in the transport path, and the light receiving means. In an image forming apparatus for detecting the presence / absence of double feeding of the recording member in the transport path and / or the paper type based on the output voltage and reference data from the registration roller, the registration roller for causing the recording member to abut and deflecting, A pair of guide plates provided on the upstream side in the transport direction from the registration rollers, and one guide plate is disposed non-parallel along the transport direction with respect to the other guide plate and is emitted from the light emitting means. When the light path transmitted through the recording member is orthogonal to one of the pair of guide plates, the light path emitted from the light emitting means is orthogonal to the other guide plate. The recording member And detecting the presence / absence of double feeding of the recording member and / or the paper type in the transport path based on the highest output voltage value of the two detection results and the reference data. It is characterized by this.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the light is detected from the light emitting means for irradiating the light toward the conveyance path and the light emission means transmitted through the recording member in the conveyance path. A plurality of detection means for detecting the presence / absence of double feeding of the recording member in the transport path and / or the paper type based on the output voltage from the light receiving means and the reference data. When one of the light emitting means of the detecting means emits light, the other light emitting means is prevented from emitting light.

  According to the invention of claim 1 or 3, even if the recording member undulates up and down by detecting the transmitted light transmitted from the recording member at a plurality of locations of the recording member, any of the detection locations of the recording member is Thus, it is possible to detect transmitted light transmitted from the light emitting means toward the light receiving means and transmitted through the recording member substantially orthogonal to the recording member. The amount of light transmitted through the recording member substantially perpendicular to the recording member is larger than the amount of transmitted light transmitted through the recording member without being orthogonal to the recording member. For this reason, the output voltage when detecting the transmitted light at a position that is substantially orthogonal to the recording member and passing through the recording member is the output voltage when the transmitted light at the position that is not orthogonal to the recording member and is transmitted through the recording member is detected. Higher than voltage. Therefore, by detecting the presence / absence of double feeding of the recording member in the transport path and / or the paper type based on the highest output voltage among the output voltage values at the detection location and the reference data, the following effects can be obtained. Play. In other words, even if the recording member is wavy or curled up and down, the presence / absence of double feeding based on the output voltage when the amount of transmitted light that has passed through the recording member almost always orthogonal to the recording member is detected and / or The paper type can be detected. As a result, it is possible to accurately detect the presence / absence of double feeding of the recording member and / or the paper type even if the recording member is wavy or curled up and down.

  According to the second aspect of the present invention, even if the recording member abuts against the registration roller and bends to come into contact with either surface of the guide plate, either one of the detection results is emitted to the light receiving means. Is a detection result when the light passes through the recording member substantially orthogonal to the recording member. As a result, the recording member wavy or curled up and down hits the registration roller and bends in a different direction from the normal, and even if it comes into contact with a different guide surface, it passes through the recording member almost perpendicularly to the recording member. The presence / absence of double feed and / or the paper type can be detected based on the output voltage when the transmitted light quantity is detected.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as a copying machine) as an image forming apparatus will be described.
First, a basic configuration of the copying machine according to the present embodiment will be described. FIG. 1 is a schematic diagram showing the main part of the copying machine. In the figure, the image forming apparatus is mainly composed of an apparatus main body 100, a paper feed table 200 on which the apparatus main body is mounted, a scanner 300 attached on the apparatus main body, and an automatic document feeder (ADF) 400 attached thereon. Yes.

  The apparatus main body 100 is provided with a belt device including an intermediate transfer belt 40 formed of an endless belt. In FIG. 11, the intermediate transfer belt 40 is stretched around the driving roller 1, the supporting rollers 2 and 3, and the bending member 5, and is driven to rotate clockwise in the drawing. In this image forming apparatus, a belt cleaning device 19 for removing residual toner remaining on the intermediate transfer belt 40 after the secondary transfer is provided as the action member 30 described above. At the facing portion of the belt cleaning device 19, the above-described facing member 50 is disposed so as to always contact the inner peripheral surface of the intermediate transfer belt 40. In the apparatus main body 100, four image forming units 10 that form toner images of black, yellow, magenta, and cyan are arranged side by side along the belt outer peripheral surface of the intermediate transfer belt 40. An exposure device 13 is provided on each of these image forming units 10. A fixing device 6 is disposed below the belt device. Further, below the fixing device 6, a sheet reversing device 22 that reverses the transfer paper 18 to record images on both sides of the transfer paper 18 is provided.

  In order to form an image using this image forming apparatus, a document is set on the document table of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass of the scanner 300, and the automatic document feeder 400 is closed and pressed. Next, a start switch (not shown) is pressed. As a result, when a document is set on the automatic document feeder 400, the document is conveyed onto the contact glass. When a document is set on the contact glass, the scanner 300 is immediately driven to read the document image.

  On the other hand, when the start switch is pressed, the drive roller 1 is rotated by a drive motor (not shown). As a result, the intermediate transfer belt 40 is driven and rotated in a predetermined direction. At the same time, black, yellow, magenta, and cyan single color toner images are formed on the respective photoreceptors of the individual image forming units 10. Then, with the rotation of the intermediate transfer belt 40, these single color toner images are sequentially primary-transferred onto the intermediate transfer belt 40. As a result, a full-color composite toner image is formed on the intermediate transfer belt 40.

  When the start switch is pressed, one of the paper feed rollers 23 of the paper feed table 200 is selected and rotated. As a result, the transfer paper 18 is fed out from the corresponding one paper feed cassette 24. The transfer paper 18 is separated and conveyed one by one, and waits while being abutted against the registration roller 25. The transfer sheet 18 is fed between the intermediate transfer belt 40 and the secondary transfer roller 17 by rotating the registration roller 25 in synchronization with the composite color image on the intermediate transfer belt 40. As a result, a color image is recorded on the transfer paper 18.

The transfer paper 18 after the secondary transfer is sent to the fixing device 6. Then, the secondary transfer toner image is fixed on the transfer paper 18 by being heated and pressurized by the fixing device 6. The transfer paper 18 on which the secondary transfer toner image is fixed is discharged out of the apparatus main body and stacked on the paper discharge tray 26. When images are formed on both surfaces of the transfer paper 18, after the image is formed on the surface as described above, the switching claw 27 is switched and the transfer paper 18 is guided to the sheet reversing device 22. With this sheet reversing device 22, the image forming surface of the transfer paper 18 is reversed, and the transfer paper 18 is again guided to the secondary transfer portion. After the image is also recorded and fixed on the back surface of the transfer paper 18, the transfer paper 18 is discharged out of the apparatus main body and stacked on the paper discharge tray 26.
On the other hand, the residual toner remaining on the outer peripheral surface of the bell is removed from the intermediate transfer belt 40 after the secondary transfer by the belt cleaning device 19.

  FIG. 2 is a schematic diagram showing the main configuration around the registration roller 25 together with peripheral devices. As shown in FIG. 2, a double feed / paper type detection device 60 is provided upstream of the registration roller 25 in the transfer paper conveyance direction.

  The double feed / paper type detection device 60 includes a light emitter 61 as a light emitting means, a light receiver 62 as a light receiving means, and a power source and an amplifier circuit (not shown). The light emitter 61 is disposed on the back side of the lower guide plate 63, and the light receiver 62 is disposed on the back side of the upper guide plate. The light receiver 62 and the light emitter 61 face each other across the transfer path of the transfer paper so that the light from the light emitter 61 reaches the light receiver 62 through the detection hole of the lower guide plate 63 and the detection hole of the upper guide plate 64. Arranged to do. The transfer paper 18 discharged from the paper feed cassette 24 or the paper feed tray 28 toward the registration roller pair 25 passes between the light emitter 61 and the light receiver 62. When the transfer paper 18 enters the optical path (hereinafter referred to as detection position) of the light emitted from the light emitter 61 toward the light receiver 62, the light passes through the transfer paper 18 and becomes transmitted light, and then the light receiver 62. Is detected.

  Detection of double feed is performed as follows. That is, the amount of transmitted light that has passed through the transfer paper 18 decreases with an increase in the number of sheets of transfer paper 18 that enter the optical path, and the light receiver 62 outputs an output voltage value as the transmission amount decreases. Decrease. A control unit (not shown) in the image forming apparatus detects double feeding of the transfer paper 18 based on an output voltage value from the light receiver 62 that detects transmitted light. Specifically, the control unit stores a reference value as reference data in data storage means such as RAM and ROM (not shown), and the output voltage value from the light receiver 62 that detects transmitted light is the reference value. If it is less than that, it is determined that double feeding has occurred.

  The detection of the paper type is performed as follows. The amount of light transmitted through the transfer paper 18 varies depending on the type of the transfer paper 18 entering the optical path. Specifically, a paper type with a large paper thickness has a smaller amount of transmitted light and a lower output voltage than a paper type with a small paper thickness. In addition, a highly transparent paper type such as OHP has a larger amount of transmitted light and higher output voltage than plain paper. Thus, the output voltage value varies depending on the paper type. Therefore, a control unit in the image forming apparatus (not shown) stores the output voltage value of each paper type as reference data in a data storage means such as a RAM or ROM (not shown). Then, the paper type having the output voltage closest to the output voltage value from the light receiver 62 that detects the transmitted light is searched from the storage means, and the paper type of the transfer paper in the transport path is specified.

  FIG. 3 is a view of the multifeed / paper type detection device 60 as viewed from the direction A shown in FIG. As shown in FIG. 3, the double feed / paper type detection device 60 includes a light emitting device 61a and a first detection unit 60a including a light receiving device 62a facing the light emitting device 61a, a light emitting device 61b, and the light emitting device 61b. It consists of a second detector 60b comprising a light receiver 62b facing each other, a light emitter 61c, and a third detector 60c comprising a light receiver 62c opposed to this light emitter 61c. And the 1st detection part 60a, the 2nd detection part 60b, and the 3rd detection part 60c are provided along with the axial direction.

  The multifeed / paper type detection device 60 of the present embodiment includes an output voltage value from the light receiver 62a of the first detection unit 60a, an output voltage value from the light receiver 62b of the second detection unit 60b, and a third detection. Based on the highest output voltage value among the output voltage values from the light receiver 62c of the unit 60c, the double feed or the paper type of the transfer paper 18 is detected.

  When the transfer paper 18 undulated in the axial direction is conveyed from the paper feed cassette 24 or the paper feed tray 28 to the detection position, as shown in FIG. 3, the light emitter 61a of the first detection unit when viewed from the A direction. The angle θa between the optical path from the transfer paper 18 and the transfer paper 18 is closest to 90 ° than the angles θb, θc between the light paths from the light emitters 61 b and 61 c of the other detection units and the transfer paper 18. Therefore, the distance that the light from the light emitter 61a of the first detection unit passes through the transfer paper 18 is shorter than the other detection units 60b and 60c, and the light transmitted through the transfer paper compared to the other detection units. The amount increases. As a result, the output voltage of the light receiver 62a of the first detector 60a is higher than the output voltages of the other light receivers 62b and 62c.

  Of the three detectors 60a, 60b, and 60c, the detector having the highest output voltage value has the largest angle θ between the light path from the light emitter 61 and the transfer paper when viewed from the A direction as compared to the other detectors. It can be said that it is close to ° °. For this reason, the reference data stored in the data storage means such as RAM and ROM is determined based on the output voltage when the angle θ between the light path from the light emitter 61 and the transfer paper is 90 °. Then, it is determined that double feeding has occurred when the output voltage value of the three detection units 60a, 60b, and 60c is less than the predetermined range of the reference value. Further, a paper type having an output voltage closest to the output voltage value from the light receiver 62 is searched from storage means such as a RAM and a ROM, and the paper type of the transfer paper in the transport path is specified. As a result, even if the transfer paper is wavy in the axial direction (width direction), one of the three detectors is a portion where the angle θ between the optical path from the light emitter 61 and the transfer paper 18 is close to 90 °. Output voltage can be obtained. Of the three detectors, by detecting the double feed of the transfer paper and the paper type based on the highest output voltage, the angle θ between the optical path from the light emitter 61 and the transfer paper 18 is always close to 90 °. It is possible to detect double feeding of transfer paper and paper type based on the output voltage of the part. As a result, even if there is curling or undulation in the axial direction of the transfer paper, it is possible to detect the double feed of the transfer paper and the paper type.

  In the multifeed / paper type detection device 60 described above, detection is performed at three positions in the axial direction of the transfer paper, but more accurate detection can be performed by increasing the number of detection positions. Further, the detection unit may be configured to be movable in the axial direction, and a plurality of axial positions of the transfer paper may be detected by one detection unit.

  In addition, when the three light emitters 61a, 61b, and 61c are caused to emit light at the same time to detect the transmission amount from the transfer paper at each position in the axial direction, the light transmitted through the transfer paper from other light emitters is detected by the light receiver. Accurate detection may not be possible. For this reason, it is preferable to shift the light emission timing of each light-emitting device 61a, 61b, 61c.

  FIG. 4 is a diagram showing the light emission timing of each of the light emitters 61a, 61b, 61c. As shown in FIG. 4, first, the light emitter 61a of the first detector 60a emits light for a time t1 (5 to 20 [mS]), and the light transmitted through the transfer paper 18 is detected by the light receiver 62a. When the light emission of the light emitter 61a is completed, the light emitter 61b of the second detection unit 60b emits light for the time t1 after the passage of time t2 (5 to 10 [mS]). Then, after the light emitting device 62a emits light, the light emitting device 61c of the third detector 60c emits light for the time t1 with an interval of time t2.

  The light receivers 62a, 62b, and 62c can detect only the light of the opposing light emitters by shifting the light emission timings of the respective light emitters 61a, 61b, and 61c independently. As a result, each light receiver can accurately detect light from each light emitter that has passed through the transfer paper, and can accurately detect double feed and paper type.

  Next, a modified example of the multifeed / paper type detection device will be described. FIG. 5 is a diagram of a modified example of the multifeed / paper type detection device 160 as viewed from the A direction shown in FIG. As shown in FIG. 5, the multifeed / paper type detection device 160 includes a first detection unit 160a and a second detection unit 160b arranged in the axial direction. As shown in FIG. 6A, the first detection unit 160 a is provided so that the optical path from the light emitter 161 a is orthogonal to the guide surface 64 a of the upper guide plate 64. The second detection unit 160 b is provided so that the optical path from the light emitter 161 b is orthogonal to the guide surface 63 a of the lower guide plate 63.

As shown in FIG. 7, normally, when the leading edge of the transfer paper 18 discharged from the paper feed cassette 24 hits the registration roller 25, the transfer paper 18 bends and contacts the guide surface 64a of the upper guide plate 64. At this time, the optical path from the light emitter 161 a of the first detection unit 160 a is orthogonal to the transfer paper 18. Therefore, the distance that the light from the light emitter 161a passes through the transfer paper 18 is shorter than that of the second detector 160b, and the output voltage value of the light receiver 162a of the first detector 160a is the second detector. It becomes higher than the output voltage value of the light receiver 162b of 160b.
On the other hand, when there is curl or undulation in the transport direction (vertical direction) of the transfer paper 18 discharged from the paper feed cassette 24, when the transfer paper 18 is bent against the registration roller as shown by the dotted line in FIG. The transfer paper 18 contacts the guide surface 63a of the lower guide plate. At this time, the optical path from the light emitter 161 b of the second detector 160 b is orthogonal to the transfer paper 18. Accordingly, the output voltage value of the light receiver 162b of the second detector 160b is higher than that of the light receiver 162a of the first double feed detector.

  As shown in FIG. 8, the transfer paper 18 conveyed from the paper feed tray 28 toward the registration roller 25 normally comes into contact with the guide surface 63 a of the lower guide plate when it hits the registration roller 25. At this time, as described above, the output voltage of the second detection unit 60b in which the optical path from the light emitter 161b is orthogonal to the guide surface 63a of the lower guide plate is the highest. Further, when there is a curl or the like of the transfer paper 18, the transfer paper 18 comes into contact with the guide surface 64a of the upper guide plate when bent against the registration roller as shown by a dotted line in FIG. In this case, the light path of the light emitter of the first detector 60a is substantially orthogonal to the transfer paper, and the output voltage value of the light receiver 162a is maximized.

  As described above, the optical path from any one of the two detectors 160 a and 160 b is substantially orthogonal to the transfer paper 18. For this reason, the highest output voltage value among the output voltage value of the first detection unit 160a and the output voltage value of the second detection unit 160b is the output voltage when the optical path from the light emitter is substantially orthogonal to the transfer paper 18. Value. Therefore, if the multi-feed of the transfer paper 18 or the paper type is detected based on the highest voltage value, the transfer paper 18 may curl or undulate in the transport direction, and contact with a different guide surface. The multi-feed of the transfer paper 18 and the paper type can always be detected based on the output voltage value when the optical path from the light emitter is substantially orthogonal to the transfer paper 18.

  Further, when the paper feed cassette 24 is attached to the image forming apparatus, the paper type of the paper feed cassette 24 attached as the initial operation mode may be determined by the multifeed / paper type detection device. First, when the paper feed cassette 24 is attached to the image forming apparatus, the paper type of the paper feed cassette 24 attached as an initial operation mode is determined. Specifically, the transfer paper 18 is conveyed from the mounted paper cassette 24 to the registration roller 25, and the paper types stored in the paper cassette 24 mounted using the multifeed / paper type detection device. Determine. Then, the paper type information is stored in the recording means in the image forming apparatus, and the initial operation mode is ended. Next, when the image forming operation is executed, the image forming conditions such as the transfer electric field are changed based on the paper type information stored in the recording unit in the image forming apparatus. In addition, the reference value for double feed detection is changed based on the paper type information stored in the recording means in the image forming apparatus. Light is emitted from each of the light emitters 61a, 61b, 61c toward the transfer paper 18 discharged from the paper feed cassette 24 toward the registration roller pair 25, and the light transmitted through the transfer paper 18 is received by each of the light receivers 62a, 62b. , 62c. Among the output voltage values from each of the light receivers 62a, 62b, and 62c, the highest output voltage is compared with the reference value of the double feed detection changed based on the paper type information to detect whether or not the double feed is performed. .

(1)
As described above, according to the image forming apparatus of the present embodiment, the detection units 60a, 60b, and 60c detect light transmitted from different positions on the transfer sheet as a recording member. Then, based on the highest output voltage among the output voltage values of each detection unit and the reference data, the presence / absence of the double feeding of the transfer paper in the transport path and the paper type are detected. As a result, even if the transfer paper undulates or curls up and down, the presence / absence of double feeding based on the output voltage when the amount of transmitted light that has passed through the transfer paper almost perpendicularly to the transfer paper is detected and / or Alternatively, the paper type can be detected. As a result, it is possible to accurately detect the presence / absence of double transfer of the transfer paper and / or the type of paper even if the transfer paper is wavy or curled up and down.
(2)
Further, according to the multifeed / paper type detection device of the modified example, the optical path of the light emitted from the light emitter 161a of the first detection unit 160a is orthogonal to the guide surface 64a of the upper guide plate, and the second detection unit The optical path of light emitted from the light emitter 161b of 160b is orthogonal to the guide surface 63a of the lower guide plate. When the transfer paper 18 conveyed in the conveyance path comes into contact with the registration roller 25 and bends and comes into contact with the upper guide surface 64a, the optical path of the light emitted from the light emitter 161a of the first detection unit 160a is transferred. Orthogonal to the paper. In addition, when the transfer paper 18 conveyed in the conveyance path comes into contact with the registration roller 25 and bends and comes into contact with the lower guide surface 63a, the optical path of light emitted from the light emitter 161b of the second detection unit 160b. Is perpendicular to the transfer paper. When the transfer paper 18 comes into contact with the registration roller 25 and bends, even if the transfer paper comes into curling or the like and comes into contact with a different surface from the guide surface that normally comes into contact, the light is emitted from the light emitter of one of the detection units. The optical path of light is perpendicular to the transfer paper. As a result, paper type detection or double feed detection is performed based on the higher output voltage of the output voltage from the light receiver 162a of the first detector and the output voltage from the light receiver 162b of the second detector. Thus, even if the transfer paper has a curl or the like and contacts a guide member different from the normal one, it is possible to perform the paper type detection and the double feed detection satisfactorily.
(3)
Further, according to the image forming apparatus of the present embodiment, when one of the light emitters 61a, 61b, 60c of each of the detection units 60a, 60b, 60c emits light, the other light emitters are prevented from emitting light. . Thereby, each light receiver 62a, 62b, 62c can detect only the light of the light emitter which opposes, respectively. As a result, each light receiver can accurately detect light from each light emitter that has passed through the transfer paper, and can accurately detect double feed and paper type.

1 is a schematic configuration diagram showing a main part of a copying machine. FIG. 3 is a schematic diagram showing a main part configuration around a registration roller 25 together with peripheral devices. The figure which looked at the double feed and the paper type | mold detection apparatus 60 from the A direction shown in FIG. The figure explaining the light emission timing of each light-emitting device. The figure which looked at the double feed and paper type | mold detection apparatus of the modification from the A direction shown in FIG. (A) is a figure which shows the 1st detection part in the double feed and paper kind detection apparatus of the said modification. FIG. 6B is a diagram illustrating a second detection unit in the multifeed / paper type detection device according to the modification. 6A and 6B are diagrams illustrating bending when a transfer sheet discharged from a sheet feeding cassette comes into contact with a registration roller. 6A and 6B are diagrams illustrating bending when a transfer sheet discharged from a sheet feeding tray comes into contact with a registration roller.

Explanation of symbols

18 Transfer Paper 24 Paper Feed Cassette 25 Registration Roller 28 Paper Feed Tray 60 Double Feed / Paper Type Detection Device 61 Light Emitter 62 Light Receiver 63 Lower Guide Plate 64 Upper Guide Plate 160 Double Feed / Paper Type Detection Device

Claims (3)

A light emitting means for irradiating light toward the transport path; and a light receiving means for detecting light from the light emitting means that has passed through the recording member in the transport path. The output voltage and reference data from the light receiving means are In the image forming apparatus for detecting the presence / absence and / or the paper type of the recording member in the conveyance path based on:
A registration roller that deflects against the recording member;
A pair of guide plates provided on the upstream side in the transport direction from the registration rollers,
Output voltage value when transmitted light transmitted from the recording member is detected at a plurality of locations near the portion where the recording member is bent and contacts the guide plate, and transmitted light transmitted from the recording member at each detected location is detected. An image forming apparatus comprising: detecting presence / absence of double feeding of recording members in the conveyance path and / or paper type based on the highest output voltage and reference data. A light emitting means for irradiating light toward the transport path; and a light receiving means for detecting light from the light emitting means that has passed through the recording member in the transport path. The output voltage and reference data from the light receiving means are In the image forming apparatus for detecting the presence / absence and / or the paper type of the recording member in the conveyance path based on:
A registration roller that abuts and deflects the recording member and a pair of guide plates provided on the upstream side in the transport direction from the registration roller, and one guide plate extends in the transport direction with respect to the other guide plate. Arranged non-parallel,
The light transmitted from the recording member is detected when the optical path of the light emitted from the light emitting means is orthogonal to one of the pair of guide plates, and the optical path of the light emitted from the light emitting means is the other. The light transmitted from the recording member when it is orthogonal to the guide plate is detected, and based on the highest output voltage value of the two detection results and the reference data, the recording member double feed in the transport path An image forming apparatus characterized by detecting the presence or absence and / or paper type. The image forming apparatus according to claim 1 or 2,
A light emitting means for irradiating light toward the transport path; and a light receiving means for detecting light from the light emitting means that has passed through the recording member in the transport path. The output voltage and reference data from the light receiving means are A plurality of detection means for detecting the presence / absence of double feeding of the recording member and / or the paper type in the transport path, and when one of the light emission means of each of the detection means emits light, the other light emission means An image forming apparatus characterized by preventing light from being emitted.

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