JP2012030937A - Sheet feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the accurate thickness of a sheet.SOLUTION: This sheet feeding device includes: a sheet thickness detection roller that displaces in a direction intersecting the sheet according to the thickness of the sheet (direction perpendicular to the sheet) while nipping and feeding the sheet; a displacement detection means that detects displacement in a direction perpendicular to the sheet of the sheet thickness detection roller; a rotation cycle detection means that detects a rotation cycle of the sheet thickness detection roller; and a sheet thickness detection means that detects, as a thickness of the sheet, a value where first displacement is distracted from second displacement after synchronizing displacement (first displacement) for the sheet thickness detection roller when the sheet is not nipped and fed with displacement (second displacement) for the sheet thickness detection roller when the sheet is nipped and fed based on the rotation cycle of the sheet thickness detection roller.

Description

  The present invention relates to a sheet conveying device and an image forming apparatus.

  Image forming apparatuses such as multifunction peripherals, printers, fax machines, and the like are used to set appropriate values for various parameters that affect image formation, such as the pressure between rollers on the fixing roller and the conveyance speed of the paper discharge roller. The thickness is detected and distinguished, for example, into plain thin paper or thick paper. In such an image forming apparatus, as a method of detecting the thickness of the recording paper, the paper is sandwiched and conveyed by a pair of opposing paper thickness detection rollers, and the paper thickness detection roller according to the thickness of the recording paper A method of detecting the thickness of the paper based on the amount of displacement in the direction perpendicular to the recording paper is employed (for example, Patent Documents 1 to 3 below).

JP 2009-234698 A JP-A-1-145175 Japanese Patent Laid-Open No. 2-123055

  However, in the above prior art, the paper thickness is detected based on the displacement amount of the paper thickness detection roller. However, the cylindrical paper thickness detection roller is not necessarily a uniform circle (perfect circle). It is not eccentric and is not eccentric. For this reason, the amount of displacement of the paper thickness detection roller in the orthogonal direction of the paper includes the eccentric component of the paper thickness detection roller as an error, so that the accurate paper thickness can be detected from the amount of displacement. Can not.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to detect an accurate sheet thickness.

  In order to achieve the above object, according to the present invention, as a first solving means related to the paper transport device, the paper is nipped and transported and displaced in a direction perpendicular to the paper (paper orthogonal direction) according to the thickness of the paper. A paper thickness detecting roller, a displacement amount detecting means for detecting a displacement amount of the paper thickness detecting roller in a paper orthogonal direction, an index provided on a peripheral surface of the paper thickness detecting roller, and the index as a reference A rotation period detecting means for detecting a rotation period of the paper thickness detection roller, a displacement amount (first displacement amount) of the paper thickness detection roller when the sheet is not nipped and conveyed, and a case where the sheet is nipped and conveyed. The displacement amount (second displacement amount) of the paper thickness detection roller is synchronized based on the rotation period of the paper thickness detection roller, and the first displacement amount is calculated from the second displacement amount after synchronization. The subtracted value is detected as the paper thickness. Adopting means that comprises a sheet thickness detecting means for.

  In the present invention, as a second solving means relating to the paper conveying device, in the first solving means, the rotation period detecting means is configured to use the paper thickness based on an index provided on a peripheral surface of the paper thickness detecting roller. A means for detecting the rotation period of the detection roller is employed.

  Further, in the present invention, as a first solving means related to the image forming apparatus, there is provided a sheet conveying device adopting the first solving means, and means for forming an image on a recording sheet conveyed by the sheet conveying device. Is adopted.

  According to the present invention, the displacement amount (first displacement amount) of the paper thickness detection roller when the paper is not nipped and conveyed, and the displacement amount (second displacement) of the paper thickness detection roller when the paper is nipped and conveyed. Is detected based on the rotation period of the paper thickness detection roller, and the value obtained by subtracting the first displacement amount from the second displacement amount is detected as the sheet thickness. As described above, the value obtained by subtracting the first displacement amount from the second displacement amount after synchronization is detected as the sheet thickness, so that the eccentric component of the sheet thickness detection roller is canceled out, and the sheet thickness is reduced. Since the eccentricity component of the paper thickness detection roller is not included in the thickness, it is possible to accurately detect the thickness of the paper in which the eccentricity component of the paper thickness detection roller is not included as an error.

1 is a schematic configuration diagram of a printer A according to an embodiment of the present invention. It is a block diagram of the conveyance roller 46 of the printer A which concerns on embodiment of this invention. It is a wave form diagram which shows rotation period signal RS of printer A which concerns on embodiment of this invention, 1st displacement amount signal, CS1, 2nd displacement amount signal CS2, and paper thickness signal TS. It is a flowchart which shows operation | movement.

Embodiments of the present invention will be described below with reference to the drawings.
A printer (image forming apparatus) A according to the present embodiment is connected to a plurality of client computers via a local area network, and forms an image on a recording sheet based on an electrophotographic method when a print instruction is received from the client computer. is there. As shown in FIG. 1, the printer A includes an operation unit 1, a display unit 2, a communication I / F unit 3, an image forming unit 4, and a calculation / control unit (paper thickness detection unit) 5.

The operation unit 1 includes a menu key, an online key, a power key, a reset key, up / down / left / right keys, and other various operation keys, and outputs an operation instruction of each key to the calculation / control unit 5.
The display unit 2 is, for example, a liquid crystal monitor, and displays various screens including images and characters based on signals input from the calculation / control unit 5.
The communication I / F unit 3 is connected to an external client computer via a local area network, and transmits / receives various signals to / from the client computer.

  The image forming unit 4 forms an image on a recording sheet conveyed from the paper feed cassette 44 (see FIG. 1) under the control of the arithmetic / control unit 5, and as shown in FIG. Image forming unit 41 for forming an image made of toner corresponding to Y, C, M), intermediate transfer belt 42, primary transfer roller 43, paper feed cassette 44, pickup roller 45, transport roller 46, secondary transfer roller 47 , A fixing roller 48, a paper discharge roller 49, and a paper discharge tray 50.

  Each image forming unit 41 forms an image made of toner corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (BK), and is horizontal when viewed from the front of the printer A. As shown in FIG. 1, the photosensitive drums are arranged at predetermined intervals in the direction, and the toner images are respectively formed on the peripheral surface.

The intermediate transfer belt 42 is provided so as to be in contact with the image forming unit 41, and the toner image formed on the image forming unit 41 is primarily transferred thereto.
The primary transfer roller 43 is disposed opposite to the image forming unit 41 so as to sandwich the intermediate transfer belt 42, and applies a voltage to the intermediate transfer belt 42 while being rotationally driven under the control of the arithmetic / control unit 5. As a result, the toner image is primarily transferred from the image forming unit 41 to the intermediate transfer belt 42.
The paper feed cassette 44 is a container that stores a bundle of recording papers on which toner images are formed.
The pickup roller 45 is pivotally supported at a predetermined height on the paper feed cassette 44, is driven to rotate by a drive source such as a motor (not shown), and contacts the uppermost portion of the recording paper bundle accommodated in the paper feed cassette 44. Then, the uppermost recording sheet bundle is picked up and conveyed to the conveying roller 46.

  The conveyance roller 46 is rotated by a drive source such as a motor (not shown) and conveys the recording paper picked up by the pickup roller 45 to the secondary transfer roller 47, and detects the paper thickness together with the calculation / control unit 5. Configure functions. As shown in FIG. 2, the transport roller 46 includes a paper thickness detection roller 461, a displacement amount detection sensor (displacement amount detection means) 462, and a PI (Pulse Input) sensor (rotation period detection means) 463.

The paper thickness detection roller 461 has a function as a roller for transporting the recording paper P transported by the pickup roller 45 to the secondary transfer roller 47, and is a driving roller 461a and a driven roller 461b disposed so as to contact each other. It consists of and.
The drive roller 461a is a roller below the paper thickness detection roller 461, and a rotation shaft is rotatably fixed via a bearing. The rotation shaft is connected to a drive motor as a drive source via a clutch. Under the control of the arithmetic / control unit 5, it is configured to be rotationally driven at a predetermined rotational speed.

  The driven roller 461b is an upper roller in the paper thickness detection roller 461, and a rotary shaft is supported so as to be movable in the vertical direction so as to contact and separate from the drive roller 461a. The recording paper P is conveyed by the rotation of the driving roller 461a while the recording paper P is sandwiched. The driven roller 461b is displaced in a direction orthogonal to the sheet (paper orthogonal direction), that is, upward in FIG. 2, according to the thickness of the recording sheet P when the recording sheet P is nipped. The recording paper P is nipped and conveyed together with the driving roller 461a by contacting the surface of the recording paper P conveyed by 461a and being driven to rotate by frictional force with the recording paper P.

  The driven roller 461b is provided with a convex index 461c in a direction orthogonal to the peripheral surface. The index 461c functions as a mark serving as a reference when the rotation cycle of the paper thickness detection roller 461 is detected by the PI sensor 463.

The displacement amount detection sensor 462 detects the amount of displacement of the driven roller 461b in the vertical direction. The displacement amount detection sensor 462 includes an actuator including a lever that tilts in the vertical direction about the axis. The actuator is disposed on the rotation shaft of the driven roller 461b. The displacement of the driven roller 461b is detected based on the vertical movement of the actuator. That is, the displacement detection sensor 462 is a sensor that detects the thickness of the recording paper P. When the displacement amount detection sensor 462 detects the displacement amount of the driven roller 461b, the displacement amount sensor 462 converts the displacement amount into a voltage signal and outputs the voltage signal to the calculation / control unit 5. The voltage signal output to the displacement detection sensor 462 is converted into a digital signal by an A / D converter (not shown) provided in the calculation / control unit 5.
The PI sensor 463 is, for example, an optical sensor, and detects the rotation period of the driven roller 461b based on the index 461c. When the PI sensor 463 detects the rotation cycle of the driven roller 461b, the PI sensor 463 outputs a pulse signal corresponding to the rotation cycle to the calculation / control unit 5.

  Returning to FIG. 1, the secondary transfer roller 47 applies a voltage to the recording paper while being rotated by a drive source under the control of the calculation / control unit 5, thereby causing the intermediate transfer belt 42 and the secondary transfer roller 47 to move. The toner image on the intermediate transfer belt 42 is secondarily transferred to the recording paper conveyed in between.

The fixing roller 48 includes a heating roller provided with a heater therein and a pressure roller pressed against the heating roller, and heats the recording paper by sandwiching and conveying the recording paper on which the toner image is transferred by the two rollers. And pressurizing to fix the toner image on the recording paper.
The paper discharge roller 49 is rotationally driven by a motor (not shown), and discharges the recording paper conveyed from the fixing roller 48 to the paper discharge tray 50.
The paper discharge tray 50 is a tray that receives the recording paper discharged by the paper discharge roller 49.

  The arithmetic / control unit 5 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an interface circuit for inputting / outputting signals to / from each of the above-described units. The overall operation of the printer A is controlled based on the stored control program. The control program stored in the ROM includes a paper thickness detection program, and the calculation / control unit 5 detects the thickness of the recording paper P by calculation based on the paper thickness detection program. The details of the processing executed by the arithmetic / control unit 5 will be described as the operation of the printer A below.

Next, the operation of the printer A according to this embodiment having the above configuration will be described in detail with reference to FIG.
First, a user who intends to print using the printer A operates a client computer (see FIG. 1) and transmits a print instruction to the printer A.
When receiving a print instruction from the client computer, the arithmetic / control unit 5 conveys the recording paper P from a paper feed cassette (not shown) to a paper thickness detection roller 461 to a predetermined conveyance roller (not shown), and a driving roller 461a. , The recording paper P is conveyed to the paper thickness detection roller 461.

  In the paper thickness detection roller 461, the driven roller 461 b is displaced upward by the thickness of the recording paper P when the recording paper P is conveyed. The displacement amount detection sensor 462 outputs the displacement amount of the driven roller 461b to the calculation / control unit 5 as a voltage signal. The PI sensor 463 detects the rotation period of the driven roller 461b with reference to the index 461c, and outputs the rotation period as a pulse signal.

  When the voltage signal is input from the displacement detection sensor 462 and the pulse signal is input from the PI sensor 463, the arithmetic / control unit 5 stores both signals. That is, the calculation / control unit 5 holds the recording paper P between the voltage signal (first displacement signal CS1) indicating the displacement of the driven roller 461b in the paper thickness detection roller 461 when the recording paper P is not conveyed. A voltage signal (second displacement amount signal CS2) indicating the displacement amount of the driven roller 461b in the paper thickness detection roller 461 when conveyed, and a pulse signal (rotation cycle signal RS) indicating the rotation cycle of the driven roller 461b. Remember.

  The arithmetic / control unit 5 temporally calculates the first displacement amount signal CS1 and the rotation period signal RS based on the time information of the first displacement amount signal CS1, the second displacement amount signal CS2, and the rotation period signal RS. While synchronizing, 2nd displacement amount signal CS2 and rotation period signal RS are synchronized temporally. Then, as shown in FIG. 3, the arithmetic / control unit 5 synchronizes the first displacement amount signal CS1 and the second displacement amount signal CS2 with reference to the “ON” signal of the rotation period signal RS. The first displacement amount signal CS1 and the second displacement amount signal CS2 shown in FIG. 3 have a sine wave shape. This is because the cylindrical paper thickness detection roller 461 has a uniform circular shape. This is because it is eccentric.

  The arithmetic / control unit 5 subtracts the value of the first displacement amount signal from the value of each time of the second displacement amount signal after synchronizing. Thereby, the calculation / control unit 5 acquires the paper thickness signal TS (see FIG. 3) that is the difference between the second displacement amount signal and the first displacement amount signal, and the value of each time of the paper thickness signal TS. Is detected as the thickness of the recording paper P. The normal recording paper P has a thickness of about 90 μm, and has a width of about 50 to 250 μm from thin paper to thick paper.

  By doing so, the eccentric component included in the second displacement amount signal CS2 is canceled out by the eccentric component included in the first displacement amount signal CS1, and an accurate recording sheet thickness is detected. Can do. Based on the detected thickness of the recording paper P, the arithmetic / control unit 5 sets appropriate values for various parameters in image formation such as a fixing roller (not shown) in the image forming mechanism and a conveyance speed of the paper discharge roller. To do.

  As described above, in the present embodiment, when the recording paper P is nipped and conveyed, the first displacement amount signal CS1 indicating the displacement of the driven roller 461b of the paper thickness detection roller 461 when the recording paper P is not nipped and conveyed. The second displacement amount signal CS2 indicating the displacement amount of the paper thickness detection roller 461 is synchronized on the basis of the rotation period of the paper thickness detection roller 461, and is synchronized with each of the second displacement amount signals CS2. A value obtained by subtracting the value of the first displacement amount signal CS1 from the time value is detected as the thickness of the recording paper P. By doing so, the eccentricity component included in the second displacement amount signal CS2 is canceled out by the eccentricity component included in the first displacement amount signal CS1, so that the eccentricity of the paper thickness detection roller 461 is offset. It is possible to detect an accurate sheet thickness in which components are not included as errors.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the paper conveying apparatus of the present invention is applied to the printer A which is an image forming apparatus, but the present invention is not limited to this.
For example, the paper conveying apparatus of the present invention may be applied to an image reading apparatus that conveys original paper.

(2) In the above embodiment, in order to detect the rotation period of the paper thickness detecting roller 461, the index 461c is provided on the peripheral surface of the driven roller 461b, and the PI sensor 463 is a paper thickness detecting roller based on the index 461c. Although the rotation period of 461 is detected, the present invention is not limited to this.
For example, a rotation sensor may be attached to the rotation shaft of the driven roller 461b, the rotation sensor may detect the rotation cycle of the driven roller 461b, and output a signal corresponding to the rotation cycle to the calculation / control unit 5.

(3) Although the displacement amount detection sensor 462 that detects the displacement amount of the driven roller 461b based on the vertical movement of the actuator is used in the above embodiment, the present invention is not limited to this.
For example, the displacement amount of the driven roller 461b may be detected using an optical sensor.

(4) In the above embodiment, the arithmetic / control unit 5 detects the average value of the time values of the paper thickness signal TS as the thickness of the recording paper P, but the present invention is not limited to this.
For example, the calculation / control unit 5 calculates an average value from the value of each time value of the paper thickness signal TS, excluding a value outside a predetermined range, that is, an abnormal value, and calculates the average value as the recording paper P You may make it detect as thickness of this. Further, the calculation / control unit 5 may detect the value of the predetermined time in the paper thickness signal TS as the thickness of the recording paper P without calculating the average value.

DESCRIPTION OF SYMBOLS A ... Printer, 1 ... Operation part, 2 ... Display part, 3 ... Communication I / F part, 4 ... Image formation part, 5 ... Calculation / control part (paper thickness detection means), 41 ... Image formation unit, 42 ... Middle Transfer belt, 43 ... primary transfer roller, 44 ... paper feed cassette, 45 ... pickup roller, 46 ... transport roller, 47 ... secondary transfer roller, 48 ... fixing roller, 49 ... paper discharge roller, 50 ... paper discharge tray, 461 ... paper thickness detection roller, 461a ... drive roller, 461b ... driven roller, 461c ... index, 462 ... displacement detection sensor (displacement detection means), 463 ... PI sensor (rotation period detection means), 464 ... calculation / Control unit (paper thickness detection means)

Claims (3)

A paper thickness detecting roller that sandwiches and conveys the paper and is displaced in a direction orthogonal to the paper (paper orthogonal direction) according to the thickness of the paper;
A displacement amount detecting means for detecting a displacement amount of the paper thickness detecting roller in a direction perpendicular to the sheet;
Rotation period detecting means for detecting the rotation period of the paper thickness detection roller;
The displacement amount (first displacement amount) of the paper thickness detection roller when the sheet is not nipped and conveyed and the displacement amount (second displacement amount) of the paper thickness detection roller when the sheet is nipped and conveyed are described above. And a paper thickness detecting means for detecting the value obtained by subtracting the first displacement amount from the second displacement amount as the paper thickness after synchronization based on the rotation cycle of the paper thickness detection roller. A sheet conveying apparatus characterized by the above.   The paper conveyance device according to claim 1, wherein the rotation cycle detection unit detects a rotation cycle of the paper thickness detection roller based on an index provided on a peripheral surface of the paper thickness detection roller. An image forming apparatus comprising the sheet conveying apparatus according to claim 1, wherein an image is formed on a recording sheet conveyed by the sheet conveying apparatus.

Images