JP5302818B2 - Deflection detecting device for conveying paper and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyance sheet deflection detection device and an image forming apparatus, and is suitable for use in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction peripheral (MFP) having these functions. The present invention relates to a deflection detection device and an improvement of the image forming apparatus equipped with the deflection detection device.

  Conventionally, this type of image forming apparatus forms a toner image on the surface of a rotating photoconductor based on image data read from a document, and a sheet between the rotating photoconductor and a pressure roller disposed under pressure on the photoconductor. It is well known that a toner image is transferred onto a sheet by conveying the toner, and the transferred toner is heated and fixed by a fixing unit and discharged.

  In addition, if `` wrinkles '' or `` folds '' occur in the paper being transported, the image quality of the toner image transferred and formed on the paper will be degraded, and the paper itself may be damaged. It is important to detect wrinkles and creases, and appropriate measures must be taken.

  For example, the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2007-153533 (Patent Document 1) is of this type.

  This Patent Document 1 includes a transport unit that transports a document or a recording medium as a transport object, and a transport detection unit that detects a transport object transported by the transport unit, and the transport detection unit transports the transport object. A paper jam detection function is provided on the transport path and detects whether or not the transported material is normally transported by detecting the transport state of the transported material. It is possible to detect a transport abnormality or double feed and eliminate jamming due to staying on the transport path, thereby realizing stable transport.

  In addition, Patent Document 1 includes an ultrasonic sensor arranged as a conveyance detection unit with a conveyance path of a paper interposed therebetween, and utilizes a point that a detection signal from the conveyance detection unit is lowered in a double-feed state of the sheet. Alternatively, it detects a Z-shaped paper double feed state.

JP 2007-153533 A

  However, in Patent Document 1 described above, the sheet double feed state is detected by utilizing the point that the detection signal from the conveyance detection unit decreases, but actually, for example, one sheet of paper other than the sheet double feed state is detected. It was difficult to accurately detect its own deflection.

  Therefore, as a result of observing and examining the ultrasonic characteristics and the transmission of ultrasonic waves to the paper, the present inventor radiated ultrasonic waves obliquely at a large incident angle on the paper P placed horizontally as shown in FIG. When ultrasonic waves are radiated to the floating paper P as shown in Fig. B with a small incident angle, and when a plurality of papers P are overlapped and fed as shown in Fig. C, reception by the ultrasonic sensor S is performed. As a result, the present invention was completed.

  That is, as shown in FIG. 7, the ultrasonic attenuation rate in the paper P when the ultrasonic wave is irradiated to the floating paper P at a small incident angle is more than the case of the paper P placed horizontally. However, the reception level does not decrease so much, and the reception level greatly decreases in the double feed state.

  SUMMARY An advantage of some aspects of the invention is to provide a conveyance sheet deflection detection apparatus and an image forming apparatus capable of detecting a deflection of a conveyance sheet.

In order to solve such a problem, a conveyance sheet deflection detection apparatus according to claim 1 of the present invention includes a sheet conveyance path that conveys a sheet, and a transmission unit that emits ultrasonic waves obliquely with respect to the sheet conveyance path. And a reception unit that is disposed across the paper conveyance path and receives ultrasonic waves transmitted through the paper and outputs a reception signal corresponding to the reception level. The transmission unit and the reception unit are connected to the paper conveyance path. A transmission / reception unit arranged obliquely, a received signal output by irradiating the ultrasonic wave to the paper at a smaller incident angle than when the paper passes linearly on the paper conveyance path, and a predetermined detection reference value And a detection unit for detecting the deflection of the paper.

The conveyance sheet deflection detection device according to the present invention is configured using a value larger than the reception signal level from the transmission / reception unit when one sheet of paper passes linearly on the sheet conveyance path as the detection reference value. It is.

In the conveyance sheet deflection detection device according to the present invention, the detection unit converts the conveyance speed on the leading side of the sheet on the conveyance path according to the detected deflection amount into a speed control signal that varies the detected deflection amount. An output configuration is also possible.

The conveyance sheet deflection detection device according to the present invention has a configuration in which the detection unit detects double feeding of the sheet when the reception signal is smaller than the detection reference value and the reception signal associated with one linear sheet. ing.

An image forming apparatus according to the present invention includes the above-described conveyance sheet deflection detection apparatus and an image image forming unit that forms an image on a sheet based on image data.

In such a conveyance sheet deflection detection apparatus according to the present invention, a reception signal corresponding to the reception level of the ultrasonic wave obtained by emitting ultrasonic waves obliquely from the transmission / reception unit to the sheet conveyance path and transmitting through the sheet. , And the detection unit compares the received signal with a predetermined detection reference value to detect the deflection of the sheet, so that the deflection of the conveyance sheet can be detected using ultrasonic waves.

In the conveyance sheet deflection detection apparatus according to the present invention, the detection reference value is configured to use a value larger than the reception signal level from the transmission / reception unit when one sheet of paper passes linearly on the sheet conveyance path . Therefore, accurate and reliable deflection detection of the transport sheet is possible.

In the conveyance sheet deflection detection apparatus according to the present invention, the detection unit variably controls the conveyance speed on the leading side of the sheet on the sheet conveyance path according to the detected deflection amount, so that the deflection of the sheet having the deflection can be eliminated. is there.

In the conveyance sheet deflection detecting device according to the present invention, when the received signal is smaller than the detection reference value and the received signal related to one linear sheet, the detection unit detects double feeding of the sheet. Both transmissions can be detected.

1 is a schematic block diagram showing an embodiment of a conveyance sheet deflection detection apparatus according to the present invention together with an image forming apparatus. 1 is a main part configuration diagram showing an internal configuration of an image forming apparatus according to the present invention. It is a figure explaining embodiment of the conveyance paper deflection | deviation detection apparatus which concerns on this invention. It is a figure explaining operation | movement of the conveyance paper deflection | deviation detection apparatus which concerns on this invention. It is a figure explaining operation | movement of the conveyance paper deflection | deviation detection apparatus which concerns on this invention. It is a figure used as a reference of the conveyance paper deflection | deviation detection apparatus which concerns on this invention. It is a figure used as a reference of the conveyance paper deflection | deviation detection apparatus which concerns on this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a conveyance sheet deflection detection apparatus and an image forming apparatus according to the present invention will be described below with reference to the drawings.

  The conveyance sheet deflection detecting device of the present invention will be described in the process of describing the image forming apparatus according to the present invention.

  FIG. 1 is a schematic block diagram showing an embodiment of an image forming apparatus including a conveyance sheet deflection detecting device according to the present invention, and FIG. 2 is a main part configuration diagram for explaining an internal configuration of the image forming apparatus in FIG. .

  In FIG. 1, the image forming apparatus A includes an image reading unit 3, a storage unit 5, an operation panel unit 7, a printing unit 9, and a communication unit 11 connected to the main control unit 1. For example, a multifunction device. The image forming apparatus A has other constituent elements than these, but is not a main part of the present invention, and thus description and illustration thereof are omitted. The function of the main control unit 1 will be described later.

  As shown in FIG. 2, the image reading unit 3 is disposed on the upper part of the main body case 13 under the control of the main control unit 1. The image reading unit 3 optically reads an image from a document and performs electronic processing such as filtering. This is a known scanner that generates a print job, and the generated image data is sequentially stored in the storage unit 5 for each page of the document.

  The storage unit 5 is a readable / writable non-volatile memory, such as a hard disk (HDD), that stores image data from the image reading unit 3 or the communication unit 11, a detection reference value described later, and the like under the control of the main control unit 1. .

  As shown in FIG. 2, the operation panel unit 7 serves as a well-known, for example, liquid crystal display display unit disposed on the upper portion of the main body case 13 and a touch switch type input unit, and controls the main control unit 1. The display unit is a display unit that displays an operation state and various data in the image forming apparatus A, and an operation unit that receives an operation instruction input of the device A.

  Under the control of the main control unit 1, the printing unit 9 predetermines a paper feed stage 15 on which paper is set and a paper sheet that is primarily fed from the paper feed stage 15 and conveyed, as shown in FIG. The registration roller 17 that performs the secondary paper feeding with an interval of and the paper deflection detection unit device of the present invention that detects the deflection of the paper in the course of the conveyance of the secondary paper (hereinafter including the drawings) (Abbreviated as a deflection detecting device) 19, a rotating photosensitive member 21 on which a toner image is formed based on image data read out from the storage unit 5, and a rotating photosensitive member for transferring the toner image onto a secondary sheet. A monochrome or color image forming unit having a pressure roller 23 pressed against the body 21 and a fixing unit 25 positioned downstream of the rotary photosensitive member 21 and the pressure roller 23 to fix the transferred toner image. is there.

  For example, as shown in FIG. 3, the deflection detection device 19 includes a paper transport path 27 that transports the paper secondarily fed by the registration rollers 17 toward the rotary photosensitive member 21 and the fixing unit 25, and the paper transport path 27. A transmission / reception unit 29 that emits ultrasonic waves from an oblique direction, receives ultrasonic waves transmitted through the paper on the paper conveyance path 27, and outputs a reception signal corresponding to the reception level; And a detection unit 31 that detects the deflection of the sheet by comparing the received signal with a predetermined detection reference value.

  Reference numerals 27a and 27b in FIG. 3 denote a paper feed roller that feeds paper and a transport roller that transports the fed paper, forming a paper transport path 27, and the registration roller 17 is a paper feed roller 27a. Sometimes also.

  The transmission / reception unit 29 is disposed on the upper side of the paper conveyance path 27 and transmits a ultrasonic wave from an oblique direction toward the paper conveyance path 27. The transmission / reception unit 29 is shared with the transmission unit 29a on the lower side of the paper conveyance path 27. And a receiving unit 29b that receives the ultrasonic waves.

  The transmission unit 29a emits ultrasonic waves toward the paper conveyance path 27 in an oblique direction, for example, 10 to 30 degrees with respect to the paper conveyance path, toward the reception unit 29b. The reception unit 29b transmits ultrasonic waves through the paper. And an analog reception signal corresponding to the reception level is output to the detection unit 31.

  The detection unit 31 has a function of converting an analog reception signal from the transmission / reception unit 27b into a digital reception signal, and from when the paper blocks the ultrasonic emission axis passing through the centers of the transmission unit 29a and the reception unit 29b until the paper passes. The received signal is acquired linearly, the received signal is compared with the detection reference value in the storage unit 5, and if the received signal becomes larger than the detection reference value, it is determined that the deflection of the sheet has occurred, and the detection signal It has a function to output.

  For example, as shown in FIG. 4, in the period from when the leading edge of the paper reaches between the transmitting section 29a and the receiving section 29b and the detection is started until the detection is passed through the trailing edge of the paper, the received signal level is When a time point that rises and exceeds the detection reference value is detected, it has a function of discriminating that paper deflection has occurred and outputting a detection signal.

  The detection reference value is a value larger than the reception signal level output from the detection unit 31 when one sheet of paper passes linearly on the sheet conveyance path 27.

  If the received signal level as the detection reference value is increased, a large deflection can be detected, and if it is decreased, a small deflection can be detected. However, it is preferably set to several tens% or more from the viewpoint of preventing malfunction. .

  The detection unit 31 compares the received signal with the detection reference value, and if the received signal level exceeds the detection reference value and further falls below the level of the received signal obtained by passing through one linear sheet ( It is also possible to provide a function of determining that double feeding of paper has occurred and outputting a detection signal.

  The communication unit 11 in FIG. 1 has a function of transmitting and receiving image data and the like to and from an external image forming apparatus (not shown) under the control of the main control unit 1.

  The main control unit 1 includes a CPU, a ROM that stores a startup program for the CPU, and the like, and controls the image reading unit 3, the storage unit 5, the operation panel unit 7, the printing unit 9, and the communication unit 11 with an operation program, The image data read from the image reading unit 3 and stored in the storage unit 5 is transferred to the printing unit 9 to perform print control (image formation control).

  Next, an example of the operation of the above-described conveyance sheet deflection detection apparatus of the present invention will be briefly described with reference to FIG.

  As shown in FIG. 4A, after the paper P is fed by the paper feed roller 27a and the leading edge of the paper reaches the transmission / reception unit 29 (detection start), the ultrasonic wave from the transmission unit 29a is attenuated. As shown in FIG. 5, the received signal with the lowered reception level is output to the detection unit 31.

  Then, as shown in FIG. 4B, the reception level continues to decrease until the rear end of the paper P passes through the transmission / reception unit 29 (end of detection), and then returns to the original level.

  When the deflection of the paper P occurs, for example, as shown in FIG. 4C, after the leading edge of the paper reaches the transmission / reception unit 29 until the trailing edge of the paper P passes through the transmission / reception unit 29, as described above, the paper P The attenuation rate of the ultrasonic wave passing through the inside decreases, and as shown by the broken line in FIG. 5, when the reception level of the ultrasonic wave at the receiving unit 29b increases and exceeds the detection reference value, the detecting unit 31 becomes abnormal. Is detected and a deflection detection signal is output.

  Therefore, if the detection reference value is appropriately selected, the deflection of the paper P can be detected.

  As described above, the conveyance sheet deflection detection apparatus (deflection detection apparatus 19) of the present invention emits ultrasonic waves obliquely to the sheet conveyance path 27 and the sheet conveyance path 27 and transmits the sheet P from the conveyance path side. Transmission / reception unit 29 that receives the received ultrasonic wave and outputs a reception signal corresponding to the reception level, and a reception signal level from the transmission / reception unit 29 when one sheet of paper passes linearly through the transmission / reception unit 29 A larger value is used as a detection reference value, and this is compared with the received signal. When the received signal exceeds the detected value, the detecting unit 31 detects the deflection of the paper.

  Therefore, if the detection reference value for deflection detection is appropriately selected, it is possible to accurately detect the deflection of the transport sheet P using ultrasonic waves.

  In addition, since the transmitting unit 29a that emits ultrasonic waves and the receiving unit 29b that receives ultrasonic waves are arranged across the paper transport path 27, the deflection of the paper is detected from the received signal based on the ultrasonic waves transmitted through the paper P. In particular, it is possible to reliably detect the deflection of the paper by using the point that the variation of the transmitted ultrasonic wave according to the deflection of the paper P is large.

  The detection unit 31 detects the double feed state of the paper P when the reception signal from the transmission / reception unit 29 is not only smaller than the detection reference value but also smaller than the reception signal transmitted through one linear sheet. If formed so as to be possible, it is possible to cope with both deflection and double feeding of the paper P.

  Therefore, since the deflection state of the conveyed paper P can be monitored, it is possible to prevent paper wrinkles, paper breaks, and the like in the conveyance roller 27b due to abnormal conveyance, and it is easy to minimize damage to the paper P. In addition, fixing wrinkles due to the deflection of the paper P can be prevented.

  And in the conveyance paper deflection | deviation detection apparatus which concerns on this invention mentioned above, abnormality was detected at the time of a received signal exceeding a detection reference value in one place from a detection start to a detection end. When the detection reference value is exceeded, it can be detected as a deflection, and erroneous detection can be prevented.

  Furthermore, it is also possible to obtain a change pattern of the received signal at the time of occurrence of deflection as a detection reference value in advance and detect the deflection when similar to the deflection detection pattern. What is necessary is just to form.

  In the conveyance sheet deflection detection apparatus according to the present invention, the conveyance speed on the leading side of the sheet P in the sheet conveyance path 27 is output as a speed control signal that can be varied so as to reduce the detected deflection amount according to the detected deflection amount. If the detection unit 31 is formed so that, for example, the rotational speed of a drive motor (not shown) of the transport roller 27b is controlled by the speed control signal, the deflection of the sheet P in which the deflection has occurred can be eliminated.

  Further, the arrangement position of the conveyance sheet deflection detection device (deflection detection device 19) according to the present invention is arbitrary, and for example, a configuration in which the conveyance sheet deflection detection device (deflection detection device 19) is arranged between the rotating photosensitive member 21 and the fixing unit 25 is possible.

  In the present invention, paper is not limited to paper and includes various sheet media such as plastic sheets.

  Also in the image forming apparatus A equipped with the conveyance sheet deflection detection apparatus according to the present invention, it is possible to obtain the same effect as the conveyance sheet deflection detection apparatus described above.

1 Main control unit 3 Image reading unit 5 Storage unit 7 Operation panel unit (display unit, input unit)
DESCRIPTION OF SYMBOLS 9 Printing part 11 Communication part 13 Main body case 15 Paper feed stage 17 Registration roller 19 Deflection detection apparatus (conveyance paper deflection detection apparatus)
DESCRIPTION OF SYMBOLS 21 Rotating photoconductor 23 Pressure roller 25 Fixing part 27 Paper conveyance path 27a Paper feed roller 27b Conveyance roller 29 Transmission / reception part 29a Transmission part 29b Reception part 31 Detection part A Image forming apparatus (multifunction machine)
P Paper S Ultrasonic sensor

Claims (3)

A paper transport path for transporting paper,
A transmitter that emits ultrasonic waves obliquely with respect to the paper conveyance path, and the ultrasonic waves that are arranged across the paper conveyance path and transmitted through the paper and output a reception signal corresponding to the reception level A transmission / reception unit, wherein the transmission unit and the reception unit are arranged obliquely with respect to the paper conveyance path ;
As detection reference value to a value greater than the received signal level from the receiving portion when the sheet of one sheet has passed through the sheet conveying path in a straight line, comparing the detected reference value and the received signal, Detecting the deflection of the paper when the ultrasonic wave is applied to the paper at a smaller incident angle than when the paper passes linearly on the paper conveyance path and the received signal is greater than the detection reference value; A detection unit for detecting double feeding of the paper when a received signal is smaller than the detection reference value ;
A conveyance sheet deflection detection apparatus comprising: 2. The transport according to claim 1, wherein the detection unit outputs the transport speed on the leading side of the sheet on the sheet transport path as a speed control signal that is variable so as to reduce the detected deflection according to the detected amount of deflection. Paper deflection detection device. 3. An image forming apparatus comprising: the conveyance sheet deflection detection apparatus according to claim 1; and an image image forming unit that forms an image on the sheet based on image data.

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