JP6788336B2 - Sheet transfer device, image reader and image forming device - Google Patents

Description

The present invention includes a plurality of sheets are transported in a heavy since state Cie over preparative conveying device to detect whether Ru Tei, an image reading apparatus and an image forming apparatus.

Conventionally, in an image reading device such as a scanner, in a sheet transporting device that separates and conveys sheets such as documents one by one, originally, only one sheet should be conveyed, but two or more sheets are conveyed while being overlapped. It is conceivable that so-called double feeding may occur. For this reason, conventionally, it has been known that a double feed detection sensor capable of detecting double feed of the above-mentioned sheet by using an ultrasonic type transmission sensor and a reception sensor is arranged (Patent Document). 1).

In Patent Document 1, an ultrasonic transmission sensor and a reception sensor are provided facing each other so as to sandwich a transport path for guiding a sheet. Then, the receiving sensor receives the ultrasonic waves transmitted by the transmitting sensor and transmitted through the sheet, and the double feeding of the sheet is detected based on the signal output from the receiving sensor.

Such an ultrasonic type double feed detection sensor is, for example, electrically grounded to a metal portion such as a metal shaft or sheet metal arranged in a transport guide constituting a transport path, and then mounted on a housing of an image reader. It is configured to be grounded.

Japanese Patent No. 4874135

However, in the above-mentioned conventional configuration, in each transport guide, the electric ground (earth) of the ultrasonic double feed detection sensor is grounded to the metal part of the transport guide and then grounded to the device housing. , Grounding tends to be unstable. Further, the metal portion near the transport guide is charged with the sheet to be transported, and may be affected by the static electricity. In particular, the sensor on the receiving side of the ultrasonic type double feed detection sensor receives the ultrasonic signal transmitted through the sheet, so that a circuit for amplifying a weak signal is incorporated. Therefore, a weak electrostatic pulse due to static electricity generated during sheet transportation may be amplified and erroneously detected as a normal reception pulse, resulting in erroneous determination of double feeding.

This onset Ming is intended to prevent the thus whether the erroneous judgment is being conveyed in a state of overlapping a plurality of sheets.

In order to achieve the above object, the present invention
In a sheet transport device that transports sheets
The first transport means for transporting the sheet and
A transport guide forming a transport path for guiding the sheet transported by the first transport means, and a transport guide.
A transmitter for transmitting ultrasonic waves is provided in the section of the conveying path is provided, to receive outgoing ultrasonic waves from said transmitter mounted on the opposite side to the section and the transmitter relative to the conveying path A detection means having a receiver and detecting whether or not a plurality of sheets are being conveyed in an overlapping state based on the reception result of the receiver.
A first grounding means for grounding the transport guide and
A second grounding means for grounding the receiver and
With
The first grounding means grounds the transport guide by electrically connecting the transport guide to the housing of the sheet transport device.
The second grounding means grounds the receiver by electrically connecting the receiver to the housing.
The route to which the receiver is connected to the housing is different from the route to which the transport guide is connected to the housing.

According to the present invention, it is possible to prevent erroneous determination as to whether or not a plurality of sheets are conveyed in an overlapping state .

Schematic front sectional view of the document transport reading device according to this embodiment Block diagram of the document transport reading device according to this embodiment Block diagram of the double feed detection sensor according to this embodiment Schematic diagram showing the grounding state of the double feed detection sensor according to this embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail exemplarily with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless otherwise specified, the scope of the present invention is not intended to be limited to them.

A document transport reading device as an image reading device including the sheet transporting device according to the present embodiment will be described with reference to FIG. FIG. 1 is a front sectional view showing a schematic configuration of a document transport reading device according to this embodiment.

As shown in FIG. 1, the document transport reading device includes an image reading device (hereinafter referred to as “reader unit”) 150 as an image reading means and a document transport device (hereinafter referred to as ADF (Auto Document Feeder)) as a sheet transport device. It has 2 and. The reader unit 150 is an image reading device that reads an image of a sheet (hereinafter, referred to as “original”) as a scanning target on which an image is formed. The ADF2 is a document transporting device that supplies a document to the reader unit 150 to read the document, or has a document reading unit and reads one side of the document. Hereinafter, the reader unit 150 and the ADF2 will be described in order.

[Leader section]
As shown in FIG. 1, the reader unit 150 is charge-coupled with a lamp 152 that irradiates the image surface of the document D with light, and a mirror 153 that guides the reflected light from the document D irradiated by the lamp 152 to the lens 157. It is composed of an element (CCD) 158 and the like.

The lamp 152, the mirror 153, the lens 157, and the CCD 158 are attached to the optical box (reading unit) 159. The optical box 159 is coupled to the optical box moving motor 163 (see FIG. 2) by a wire (not shown). As shown in FIG. 2, the operation of the optical box moving motor 163 is controlled by the control means 94, and the optical box HP sensor 162 detects the home position position of the optical box 159. The box 159 is reciprocated in the direction of arrow A in FIG. In this way, the optical box 159 is adapted to optically scan the document placed on the platen glass 3.

The reflected light from the document obtained by scanning the document in the direction of arrow A by the optical box 159 is guided to the lens 157 by the mirror 153 and collected on the CCD 158 by the lens 157. The CCD158 photoelectrically converts the reflected light reflecting the information of the original, outputs it as an electronic image signal to a printer unit (not shown), forms an image on a recording target sheet such as a recording paper, or stores the data as data. It accumulates in.

The reader unit 150 reads the image of the original in one of the fixed reading mode (base glass document reading mode) and the scanning mode (ADF document reading mode) selected by the user. .. The fixed reading mode is a mode in which the original is placed on the platen glass 3 as described above, and the image on the original is read while moving the optical box 159 in the sub-scanning direction (direction of arrow A in FIG. 1). On the other hand, in the scanning mode, the optical box 159 is fixed at a position where an image can be read at the document reading position 160 on the platen glass (platen) 161 and the document is conveyed to pass the document reading position 160 on the document. This is the mode to read the image.

[ADF (Document Transfer Device)]
The ADF2 includes a document tray unit, a document separation unit, a document transport unit, and a double feed detection sensor, which will be described below. Each of the parts constituting the document transfer device will be described in order.

(Original tray)
As shown in FIG. 1, a pair of width direction regulating plates 19 are slidably arranged in the width direction orthogonal to the transport direction of the document on the document tray 4 on which the document D is loaded. The width direction regulating plate 19 regulates the position of the end portion of the document D loaded on the document tray 4 in the width direction so that the documents can be supplied to the inside of the ADF by aligning the positions in the width direction.

(Original separation part)
A feeding cover 11 as an opening / closing member that opens and closes with respect to the document transporting device is provided above the document transporting portion of the ADF2 above the document loading position tip side of the document tray 4. The feeding cover 11 is provided with a pickup roller 5, a document placement detection sensor lever 9, and a document tip restricting shutter 13. The document tray 4 is provided with a document placement detection sensor 40, which is a photo interrupter.

When no document is placed on the document tray 4, the document placement detection sensor 40 is shielded from light by the document placement detection sensor lever 9 as shown in FIG. When a document is placed on the document tray 4, the flag 9b of the document placement detection sensor lever 9 is pushed away by the placed document in the direction of arrow B in FIG. 1, and the light of the document placement detection sensor 40 is transmitted. To do. In this way, the document placement detection sensor 40 detects that the document has been placed on the document tray. While the document is placed on the document tray 4, the document placement detection sensor lever 9 is pushed away by the document. When the final paper of the document placed on the document tray 4 is supplied into the ADF 2 and the document runs out on the document tray 4, the document placement detection sensor lever 9 returns to the solid line position (home position) shown in FIG. .. Therefore, the document placement detection sensor 40 can detect that the document has been placed on the document tray 4 and can also detect the final paper of the document.

The separation transfer roller 8 separates and conveys the originals one by one. Therefore, the separation transfer roller 8 separates the originals one by one even when the originals are fed in a bundle state by the pickup roller 5, and feeds only one original at the uppermost position of the original bundle. When the tip of the document separated into one sheet reaches the pull-out roller pair 47 downstream of the separate transport roller 8, the drive of the separate transport roller 8 and the pickup roller 5 is cut off, and the pull-out roller pair 47 nips the separate transport roller 8. Transport the document as if it were pulled out from the section. While the originals are being conveyed by the drawing roller pair 47, the tip of the original bundle below the conveyed originals is maintained at a position upstream of the nip portion of the separation and conveying rollers 8.

(Document carrier)
The documents separated one by one are conveyed to the drawing roller pair 47 as the conveying means by the separating conveying roller 8 driven by the document conveying motor 164. Further, the document is pulled out from the separation transfer roller 8 by the pull-out roller pair 47 and is abutted against the nip portion of the stopped register roller pair 46. The operation of the document transport motor 164 is controlled by the control means 94.

A double feed detection sensor 91 is arranged in the vicinity of the transport path between the pull-out roller pair 47 and the register roller pair 46 as a double feed detection means for detecting double feed in which two or more documents are conveyed while being overlapped. Normally, the originals are separated one by one by the nip portion of the separation transfer roller 8, but if the originals cannot be separated due to an unexpected factor, the double feed detection sensor 91 detects the overlapping originals that are not separated and stops the device. It has become like.

The document is conveyed to the lead roller portion in a state where the tip is abutted against the register roller vs. 46 to correct the skew and the tip of the document is perpendicular to the transfer direction. Then, it is fed to the document reading position 160 on the surface platen glass 161 by the first lead roller pair 32. At the document reading position 160, an image of the surface of one surface of the document is read by the optical box 159 provided in the reader unit 150 while being conveyed. The original whose front surface image has been read is fed onto the back platen glass 171 by the second lead roller pair 33, and the back surface optical box 172 provided in the ADF2 reads the back surface image which is the other side of the original. The document from which the back image has been read is ejected onto the ejection tray 10 by the document ejection roller pair 18.

(Double feed detection sensor)
Here, the double feed detection sensor arranged in the transport path will be described in detail. FIG. 3 is a diagram showing a configuration of a double feed detection sensor that detects two or more double feeds of a document using an ultrasonic sensor.

In FIG. 3, D is a document to be detected, 92 is an ultrasonic transmitter that emits ultrasonic waves, and 93 is an ultrasonic receiver that receives ultrasonic waves. The ultrasonic transmitter 92 and the ultrasonic receiver 93 constituting the double feed detection sensor are arranged so as to face each other so as to sandwich a transport path (transport path) for guiding the conveyed document.

As shown in FIG. 1, the transport path is formed by a pair of transport guides 52, 53 arranged so as to face each other. The ultrasonic transmitter 92 is arranged on the lower transport guide 52, which is one of the transport guides. The ultrasonic receiver 93 is arranged on the upper transport guide 53, which is the other transport guide facing the one transport guide.

When the ultrasonic wave transmission pulse signal is input to the ultrasonic wave transmitter 92, ultrasonic waves are transmitted. When a document is present between the ultrasonic transmitter 92 and the ultrasonic receiver 93, the ultrasonic waves transmitted through the document are received by the ultrasonic receiver 93. On the other hand, when the original is not present, the ultrasonic waves from the ultrasonic transmitter 92 are directly received by the ultrasonic receiver 93.

Reference numeral 94 denotes a control means, which supplies a predetermined pulse signal to the drive means 95, and after the drive means 95 amplifies the pulse signal, the ultrasonic transmitter 92 responds to the signal-amplified ultrasonic transmission pulse signal. Send ultrasonic waves. Ultrasound is generally called a burst wave, which is transmitted for a plurality of cycles at a time based on a transmission pulse signal, and this burst wave is transmitted once every several ms.

If a document exists between the ultrasonic transmitter 92 and the ultrasonic receiver 93, the ultrasonic waves transmitted from the ultrasonic transmitter 92 are attenuated by the time they reach the ultrasonic receiver 93 and become very weak. It ends up. Therefore, the ultrasonic wave reception signal output by the ultrasonic wave receiver 93 is amplified by the signal amplification means 96 such as an amplifier, and is raised to a signal amplitude capable of determining double feed detection.

The ultrasonic wave reception signal amplified by the signal amplification means 96 is input to the A / D conversion means 97. The A / D conversion means 97 converts an analog ultrasonic reception signal into a digital signal and outputs it to the signal analysis means 98. Various set values such as the signal amplification factor are stored in the storage means 99, and the double feed detection operation is performed using the stored set values.

The document transport reading device of this embodiment is an image reading device provided with a fixed reading mode (base glass document reading mode) and a scanning mode (ADF document reading mode). Therefore, in order to efficiently utilize the space, the originals when using the ADF original reading mode are set substantially horizontally, and the originals are separated and conveyed one by one in the substantially horizontal state. The double feed detection sensor 91 is arranged in the horizontal transport path in order to detect whether or not the document has been double fed in the vicinity of the separation unit. That is, the ultrasonic transmitter 92 is arranged on the lower side and the ultrasonic receiver 93 is arranged on the upper side across the horizontal transport path. At this time, since paper dust tends to accumulate on the lower side of the horizontal transport path, the ultrasonic transmitter 92, which is relatively less susceptible to the influence of paper dust, is arranged. On the other hand, on the upper side of the horizontal transfer path, the ultrasonic receiver 93 is arranged so as to face the ultrasonic transmitter 92.

Further, as shown in FIG. 1, the horizontal transport path is formed by a lower transport guide 52 and an upper transport guide 53 arranged so as to face the transport guide 52. In this horizontal transport path, when a paper jam occurs, the upper transport guide 53 can be rotated around the fulcrum 105 and opened so that the paper jam can be easily dealt with. That is, the upper transport guide 53, together with the pickup roller 5, the document placement detection sensor lever 9, the document tip regulation shutter 13, and the like described above, is attached to the feed cover 11 which can be opened and closed around the fulcrum 105 with respect to the ADF 2. It is provided.

Further, as shown in FIG. 4, the upper transport guide 53 (see FIG. 1) is provided with a driven roller 47a of a drawing roller pair 47. The driven roller shaft 49 of the driven roller 47a and the driven roller shaft abutment 48 are provided with a ground wire 50 for dropping static electricity generated during document transportation to the ground. Since the contacts of the movable portion tend to be electrically unstable as a ground, the ground wire coming out of the upper transport guide 53 is directly fixed to the device housing 100 of the ADF2 by a screw. Further, the upper transport guide 53 is provided with an ultrasonic receiver 93 that constitutes a double feed detection sensor. The ultrasonic receiver 93 converts the ultrasonic signal into an electrical analog signal and outputs the signal. If an electrostatic pulse is applied to this signal line from the outside, an erroneous determination of double feeding may occur in the subsequent signal processing process. Therefore, it is necessary to surely electrically ground it. At this time, if the ground wire 51 from the ultrasonic receiver 93 and the ground wire 50 such as the driven roller shaft 49 before being grounded to the device housing 100 are integrated, the ultrasonic waves are generated before the static electricity generated during document transportation falls to the ground. It affects the receiver 93. Even if the degree of influence is a minute voltage, it is amplified by the signal amplification means 96 in the subsequent stage from the ultrasonic receiver 93, which causes an erroneous determination of double feeding. Therefore, the ground wire 51 from the ultrasonic receiver 93 is electrically grounded to the device housing 100 by a dedicated wire different from the ground wire 50. That is, while the driven roller 47a is grounded to the device housing 100 after being grounded to the upper transport guide 53, the ultrasonic receiver 93 of the double feed detection sensor is directly grounded to the device housing 100. There is.

As described above, according to the present embodiment, the ultrasonic receiver 93 of the double feed detection sensor is grounded to the device housing 100 with the driven roller 47a constituting the transport means. Therefore, the double feed detection sensor is electrically and reliably grounded, and stable double feed detection performance can always be exhibited.

The number of ground wires dropped from the metal part of the transport guide to the device housing may be one or multiple, and a ground wire different from the ground wire (dedicated line) from the ultrasonic receiver may be used. All you need is.

Further, in the above-described embodiment, a sheet transport device for transporting a sheet such as a document as a scanning target has been exemplified, but the present invention is not limited to this, and a sheet such as recording paper as a recording target is transported. The same effect can be obtained by applying it to a sheet transfer device.

Further, in the above-described embodiment, a scanner provided with an ADF is exemplified as an image reading device, but the present invention is not limited thereto. For example, another image reading device such as a copying machine or a facsimile device, or another image reading device such as a multifunction device combining these functions may be used, and the present invention is applied to the sheet transporting device of the image reading device. By doing so, the same effect can be obtained.

D ... Manuscript 2 ... ADF
8 ... Separate transfer roller 11 ... Feed cover 47 ... Pull-out roller pair 50, 51 ... Ground wire 52, 53 ... Transfer guide 91 ... Double feed detection sensor 92 ... Ultrasonic transmitter 93 ... Ultrasonic receiver 100 ... Device housing 105 ... fulcrum 150 ... leader 159 ... optical box

Claims (8)

In a sheet transport device that transports sheets
The first transport means for transporting the sheet and
A transport guide forming a transport path for guiding the sheet transported by the first transport means, and a transport guide.
A transmitter for transmitting ultrasonic waves is provided in the section of the conveying path is provided, to receive outgoing ultrasonic waves from said transmitter mounted on the opposite side to the section and the transmitter relative to the conveying path A detection means having a receiver and detecting whether or not a plurality of sheets are being conveyed in an overlapping state based on the reception result of the receiver.
A first grounding means for grounding the transport guide and
A second grounding means for grounding the receiver and
With
The first grounding means grounds the transport guide by electrically connecting the transport guide to the housing of the sheet transport device.
The second grounding means grounds the receiver by electrically connecting the receiver to the housing.
A sheet transport device, characterized in that the route to which the receiver is connected to the housing is different from the route to which the transport guide is connected to the housing. The first grounding means includes a first wiring in which one end is electrically connected to the transport guide and the other end is electrically connected to the ground.
The sheet transport device according to claim 1, wherein the second grounding means includes a second wiring in which one end is electrically connected to the receiver and the other end is electrically connected to the ground. .. The first transport means and the transport guide are electrically connected to each other.
The sheet transport device according to claim 1 or 2, wherein the first transport means is grounded by the first grounding means. The sheet transport device is provided on the downstream side of the first transport means in the transport direction in which the sheet is transported, and has a second transport means adjacent to the first transport means.
The sheet transport device according to any one of claims 1 to 3, wherein the detection means is provided between the first transport means and the second transport means. The sheet transfer device has an opening / closing member that opens the transfer path.
The sheet transport device according to any one of claims 1 to 4, wherein the receiver is provided on the opening / closing member. The receiver is located on the upper transport guide, which faces the lower transport guide on which the transmitter is located.
The sheet transport device according to any one of claims 1 to 5, wherein the transport path is formed by the lower transport guide and the upper transport guide. The sheet transport device according to any one of claims 1 to 6,
An image reading means for reading an image of a sheet transported by the sheet transport device, and
An image reading device characterized by having. The image reading device according to claim 7,
An image forming means for forming an image on a recording medium based on an image read by the image reading device.
An image forming apparatus characterized by having.

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