JP2014080281A - Paper loading amount detection mechanism and image forming apparatus provided with the same - Google Patents

Abstract

To provide a sheet loading amount detection mechanism capable of changing the full detection timing of a sheet discharged to a sheet discharge unit according to needs or adjusting a sheet loading amount with respect to a curled sheet.
An actuator 20 is swingably provided on a paper discharge tray (paper discharge portion) from which paper is discharged, and the tip of the actuator 20 is brought into contact with the uppermost paper stacked on the paper discharge tray. Thus, the length of the actuator 20 can be adjusted in a paper load detection mechanism for detecting the paper load. For example, the length of the actuator 20 is adjusted by screwing a separate adjustment member 20B to the tip of the actuator 20 and rotating the adjustment member 20B. The actuator 20 is provided with a scale 23 indicating a length adjustment amount. Further, a spring (elastic member) 22 is provided in the middle portion of the actuator 20 in the longitudinal direction.
[Selection] Figure 3

Description

  The present invention relates to a sheet stacking amount detection mechanism for detecting a stacking amount of sheets discharged to a sheet discharge unit and an image forming apparatus including the same.

  In an image forming apparatus such as a copying machine or a printer that forms an image on a sheet by electrophotography, a latent image formed on an image carrier such as a photosensitive drum is developed with toner in a developing device to form a toner image. The toner image is visualized and the toner image is transferred onto the paper. The sheet onto which the toner image has been transferred is conveyed to a fixing device, where the toner image is fixed by being heated and pressed in the process of passing through the fixing nip between the heating roller and the pressure roller of the fixing device. In response, the paper on which the toner image has been fixed is discharged to a paper discharge unit outside the apparatus, and a series of image forming operations is completed.

  By the way, the paper discharge unit is provided with a paper stack amount detection mechanism for detecting the stack amount of the paper discharged and stacked on the paper discharge unit. The leading end of the actuator provided on the sheet is brought into contact with the uppermost sheet stacked on the sheet discharge unit, and the stacking amount of the sheet is detected by the swing angle of the actuator. When the detected sheet stacking amount reaches a predetermined value and a full state is detected, further image forming operations in the image forming apparatus are prohibited.

  By the way, in Patent Document 1, an elastic deformation portion that can be elastically deformed in the left-right direction is provided in an intermediate portion of the detection lever (actuator) (a portion where the discharged paper does not contact), and the tip of the detection lever is fixed to a predetermined position. Proposals have been made for a shape bent upward with a curvature. According to this, even when a hand touches the detection lever or when it is carelessly handled violently, the paper can be smoothly discharged and the detection lever can be prevented from being damaged. Further, when the paper once stacked on the discharge tray is taken out and returned to the discharge tray, a gap is formed between the detection lever and the front end of the discharge tray, so that the operation can be easily performed.

JP-A-5-319678

  However, since the length of the actuator (detection lever) cannot be freely adjusted in the conventional paper load detection mechanisms including those proposed in Patent Document 1, the full detection timing is changed according to needs. In addition, there is a problem in that the paper stacking amount cannot be adjusted with respect to the curled paper.

  The present invention has been made in view of the above-mentioned problems. The purpose of the present invention is to change the full detection timing of the paper discharged to the paper discharge unit according to needs, or to change the paper loading amount for curled paper. An object of the present invention is to provide a sheet load detection mechanism that can be adjusted and an image forming apparatus including the same.

  In order to achieve the above object, according to the first aspect of the present invention, an actuator is swingably provided on a paper discharge unit from which paper is discharged, and a leading end portion of the actuator is placed on the uppermost paper stacked on the paper discharge unit. In the sheet loading amount detection mechanism for detecting the sheet loading amount by contacting the actuator, the length of the actuator can be adjusted.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the length of the actuator is adjusted by screwing a separate adjustment member into the tip of the actuator and rotating the adjustment member. And

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a scale indicating a length adjustment amount is attached to the tip of the actuator.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the actuator is divided into a base end portion and a tip end portion, and the base end portion and the tip end portion are connected by an elastic member. It is characterized by.

  According to a fourth aspect of the present invention, there is provided an image forming unit for forming an image on an image carrier by electrophotography, a paper feeding unit for feeding paper to the image forming unit, and the image forming unit by the paper feeding unit. An image forming apparatus comprising: a fixing unit that fixes an image transferred onto a sheet fed to a sheet; and a sheet discharge unit on which the sheet on which the image is fixed is discharged and stacked. 4 is provided with the paper stacking amount detection mechanism described in any one of 4 above.

  According to the first aspect of the present invention, since the length of the actuator can be adjusted, the full detection timing of the paper discharged to the paper discharge unit can be changed according to the needs, or the paper stacking amount can be increased with respect to the curled paper. Can be adjusted.

  According to the second aspect of the present invention, the length of the actuator can be freely adjusted by rotating a separate adjustment member screwed into the tip of the actuator.

  According to the third aspect of the present invention, the length of the actuator can be finely adjusted using the scale on the actuator as a guide.

  According to the fourth aspect of the present invention, since the elastic member is provided in the longitudinal direction intermediate portion of the actuator, when the discharged paper is taken out and the actuator is touched with a hand, a large impact is applied to the actuator. The elastic member is elastically deformed to absorb the impact, and the actuator is prevented from being damaged and the durability thereof is enhanced.

  According to the fifth aspect of the present invention, the fullness detection timing of the paper discharged to the paper discharge unit can be changed according to needs and the paper stacking amount can be adjusted with respect to the curled paper. This prevents the occurrence of problems such as prohibiting image forming operations before the paper is full, or pushing out the paper that has been ejected and stacked on the paper ejection unit from the paper ejection unit. The load amount of curled paper can be adjusted appropriately.

1 is a longitudinal sectional view of an image forming apparatus according to the present invention. FIG. 3 is a longitudinal sectional view of a paper discharge unit of the image forming apparatus according to the present invention. FIG. 3 is a perspective view of an actuator of the paper stack amount detection mechanism according to the first embodiment of the present invention. FIG. 10 is a perspective view of an actuator of a paper stack amount detection mechanism according to Embodiment 2 of the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
[Image forming apparatus]
FIG. 1 is a longitudinal sectional view of an image forming apparatus according to the present invention, FIG. 2 is a longitudinal sectional view of a paper discharge unit of the image forming apparatus, and the image forming apparatus 1 shown in FIG. 1 can form images on both sides of a sheet. In the upper part of the apparatus main body 1A, a paper discharge tray 2 constituting a paper discharge unit is provided. An image forming unit 3 is disposed inside the apparatus main body 1A, and a paper feeding unit 4 is disposed below the image forming unit 3.

  The image forming unit 3 forms an image by an electrophotographic method. The image forming unit 3 is a photosensitive drum 5 as a rotatable image carrier, a charging roller 6 disposed around the photosensitive drum 5, and a laser scanner unit ( LSU) 7, a developing device 8, a transfer roller 9, and a cleaning device 10.

  The paper feed unit 4 includes a detachable paper feed cassette 11 and a pick roller 12 disposed in the vicinity thereof. Here, a plurality of sheets S are stacked and accommodated in the sheet feeding cassette 11, and the sheets S in the sheet feeding cassette 11 are sequentially picked up from the upper one by the pick roller 12, and are fed to the sheet conveyance path P1. Is sent out. Here, the paper transport path P1 extends upward from the paper feed section 4 to the paper discharge tray 2, and the registration rollers 13, the image forming section 3, and the fixing device 14 are provided on the paper transport path P1 from below. The paper discharge rollers 15 are sequentially arranged. As shown in FIG. 2, the paper discharge unit is provided with a swingable actuator 20 constituting a paper stacking amount detection mechanism according to the present invention.

  Further, a reverse conveyance path P2 is branched from the downstream side of the fixing device 14 in the paper conveyance path P1, and this reverse conveyance path P2 extends in the U-shape after extending downward on the side of the paper conveyance path P1. It turns upward and joins the upstream side of the registration roller 13 in the paper conveyance path P1. A reverse conveyance roller 16 is disposed in the middle of the reverse conveyance path P2.

  Next, an image forming operation of the image forming apparatus 1 configured as described above will be described.

  When the image forming operation is started, in the image forming unit 3, the photosensitive drum 5 is rotationally driven in a direction indicated by an arrow (clockwise) in FIG. 1 by a driving unit (not shown), and the surface thereof is set to a predetermined potential by the charging roller 6. Uniformly charged. When a laser beam is output from the laser scanner unit 7 and the surface of the photosensitive drum 5 is exposed and scanned, an electrostatic latent image corresponding to image information is formed on the photosensitive drum 5. Then, the electrostatic latent image formed on the photosensitive drum 5 is developed by the developing device 8 using toner as a developer to be visualized as a toner image.

  Further, the paper S accommodated in the paper feed cassette 11 of the paper feed unit 4 is picked up from the uppermost one by the pick roller 12 and sent out to the paper transport path P1. Then, the sheet S sent out to the sheet conveyance path P1 in this way is conveyed to the registration roller 13 through the sheet conveyance path P1 and is temporarily set in the registration roller 13, and then the toner on the photosensitive drum 5. The image is supplied to the image forming unit 3 at a predetermined timing synchronized with the image.

  In the image forming unit 3, the sheet S supplied to the transfer nip between the photosensitive drum 5 and the transfer roller 9 is conveyed while being pressed against the photosensitive drum 5 by the transfer roller 9, so that the surface thereof is exposed to light. The toner image on the drum 5 is transferred. Then, the sheet S on which the toner image is transferred is conveyed to the fixing device 14 and is heated and pressed in the process of passing through the fixing nip between the heating roller 14a and the pressure roller 14b of the fixing device 14 to be toner. Receive image fixing. The toner remaining on the surface of the photosensitive drum 5 (transfer residual toner) after the transfer of the toner image onto the paper S is removed by the cleaning device 10, and the photosensitive drum 5 whose surface has been cleaned is prepared for the next image forming operation. .

  Thus, when an image is formed on only one side of the sheet S, the sheet S on which the toner image is fixed on the surface by the fixing device 14 is conveyed to the sheet discharge roller 15 along the sheet conveyance path P1. Then, the paper is discharged onto the paper discharge tray 2 by the paper discharge roller 15 to complete a series of image forming operations.

  When images are formed on both sides of the paper S, the paper S on which the image has been formed on one side through the series of processes described above is discharged before being discharged to the paper discharge tray 2 by the paper discharge roller 15. The paper roller 15 is reversed, and the paper S sandwiched between the paper discharge rollers 15 is switched back and guided to the reverse conveyance path P2. Then, the sheet S guided to the reverse conveyance path P2 is conveyed to the registration roller 13 with its front and back being reversed in the process of being conveyed along the reverse conveyance path P2 by the reverse conveyance roller 16.

On the other hand, in the image forming unit 3, the next toner image is formed on the photosensitive drum 5 through the same process as described above, and the sheet S is imaged by the registration roller 13 at a timing synchronized with the toner image on the photosensitive drum 5. The sheet S is conveyed to the forming unit 3 and conveyed while being pressed against the photosensitive drum 5 by the transfer roller 9, so that the toner image on the photosensitive drum 5 is formed on the surface (the surface on which the image is not formed). Transcribed. Then, the sheet S on which the toner image is transferred is conveyed to the fixing device 14 and is heated and pressed in the process of passing through the fixing nip between the heating roller 14a and the pressure roller 14b of the fixing device 14 to be toner. After receiving the fixing of the image, the paper is discharged onto the paper discharge tray 2 by the paper discharge roller 15 to complete a series of image forming operations.
[Paper load detection mechanism]
Next, the paper load detection mechanism according to the present invention will be described.

<Embodiment 1>
FIG. 3 is a perspective view of an actuator constituting the paper stacking amount detection mechanism according to Embodiment 1 of the present invention. The paper stacking amount detection mechanism is a stacking amount of the paper S that is discharged and stacked on the paper discharge tray 2. And includes an actuator (detection unit) 20 provided so as to be capable of swinging, and a PI sensor (signal generation unit) (not shown) that detects the posture (swing angle, etc.) of the actuator 20. Switch mechanism. In this sheet stacking amount detection mechanism, the leading end of the actuator 20 is brought into contact with the uppermost sheet S stacked on the sheet discharge tray 2, and the posture (swing angle, etc.) of the actuator 20 is detected by the PI sensor. Thus, the loading amount of the paper S is detected. When the detected sheet stacking amount reaches a predetermined value and a full state is detected, further image forming operations in the image forming apparatus 1 shown in FIG. 1 are prohibited.

  Thus, in the present embodiment, the length of the actuator 20 whose upper end portion is supported by the shaft 21 so as to be swingable can be adjusted. Specifically, the columnar main body 20A of the actuator 20 is divided into two divided pieces 20A1 and 20A2 as shown in FIG. 3A, and both the divided pieces 20A1 and 20A2 are separated by a spring 22 which is an elastic member. It is connected. A separate bottomed cylindrical adjustment member 20B is screwed to the tip of the split piece 20A2. By rotating the adjusting member 20B as shown in FIG. 3B, the adjusting member 20B moves forward and backward with respect to the divided piece 20A2, thereby adjusting the entire length of the actuator 20. Further, a scale 23 indicating the length adjustment amount is attached to the outer periphery of the divided piece 20A2 of the actuator 20.

  Thus, in the paper stacking amount detection mechanism according to the present embodiment, the length of the actuator 20 can be adjusted, so that the full detection timing of the paper S discharged and stacked on the paper discharge tray 2 is matched to the needs. Can be changed or the paper stacking amount can be adjusted for curled paper. For this reason, in the image forming apparatus 1 shown in FIG. 1, the image forming operation is prohibited before the sheet stacking amount becomes full, or the sheet S discharged and stacked on the discharge tray 2 is discharged later. The occurrence of the problem of being pushed out of the paper discharge tray 2 by S can be prevented, and the load amount of curled paper can be adjusted appropriately.

  Further, in the present embodiment, since the separate adjustment member 20B is screwed to the tip of the split piece 20A2 of the actuator 20, the adjustment member 20B is rotated as shown in FIG. The length can be adjusted freely. In this case, since the scale 23 indicating the length adjustment amount is attached to the outer periphery of the divided piece 20A2, the length of the actuator 20 can be finely adjusted using the scale 23 as a guide.

  Further, in the present embodiment, since the divided pieces 20A1 and 20A2 constituting the main body 20A of the actuator 20 are connected by the spring 22, for example, when the sheet S discharged and stacked on the discharge tray 2 is taken out, the actuator When a hand touches 20 and a large impact is applied to the actuator 20, the spring 22 is elastically deformed to absorb the impact as shown in FIG. As a result, the actuator 20 is prevented from being damaged and the durability thereof is enhanced. If the spring 22 is covered with a flexible tube, the paper can be prevented from being caught by the spring 22.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a perspective view of an actuator of the paper load detection mechanism according to the second embodiment of the present invention. In FIG. 4, the same elements as those shown in FIG. The re-explanation about them is omitted.

  In this embodiment, the divided pieces 20A1 and 20A2 constituting the main body 20A of the actuator 20 are connected by a rubber member 24, which is a round bar-like elastic body, instead of the spring 22 (see FIG. 3) of the first embodiment. The other structure is the same as that of the first embodiment.

  Thus, also in the present embodiment, the length of the actuator 20 can be freely adjusted by rotating the adjusting member 20B as shown in FIG. 4B, and at that time, the outer periphery of the divided piece 20A2 can be adjusted. The length of the actuator 20 can be finely adjusted with reference to the scale 23 attached to.

  When a large impact is applied to the actuator 20, the rubber member 24 is elastically deformed and absorbs the impact as shown in FIG. 4C, so that the actuator 20 can be prevented from being damaged. Durability is increased.

  Also in the present embodiment, since the length of the actuator 20 can be adjusted, the full detection timing of the paper S discharged to the paper discharge tray 2 can be changed according to needs, or the paper stacking on the curled paper can be performed. The same effect as the first embodiment that the amount can be adjusted is obtained.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Image forming apparatus main body 2 Paper discharge tray (paper discharge part)
3 Image forming unit 4 Paper feeding unit 5 Photosensitive drum 6 Charging roller 7 Laser scanner unit (LSU)
DESCRIPTION OF SYMBOLS 8 Developing device 9 Transfer roller 10 Cleaning device 11 Paper feed cassette 12 Pick roller 13 Registration roller 14 Fixing device 14a Heating roller 14b Pressure roller 15 Paper discharge roller 16 Reverse conveyance roller 20 Actuator 20A Actuator main body 21 Shaft 22 Spring (elasticity) Element)
23 Scale 24 Rubber member (elastic member)
P1 Paper transport path P2 Reverse transport path S Paper

Claims (5)

A paper loading amount for detecting a paper loading amount by providing an actuator swingably on a paper discharging portion where paper is discharged and bringing the tip of the actuator into contact with the topmost paper stacked on the paper discharging portion. In the detection mechanism,
A paper loading amount detection mechanism characterized in that the length of the actuator can be adjusted.   2. The sheet stacking amount detection mechanism according to claim 1, wherein a length of the actuator is adjusted by screwing a separate adjustment member into the tip of the actuator and rotating the adjustment member.   3. A paper load detection mechanism according to claim 1, wherein a scale indicating a length adjustment amount is attached to a tip portion of the actuator.   The sheet amount detection stack according to any one of claims 1 to 3, wherein the actuator is divided into a base end portion and a front end portion, and the base end portion and the front end portion are connected by an elastic member. amount. An image forming unit that forms an image on an image carrier by an electrophotographic method, a paper feeding unit that feeds paper to the image forming unit, and a transfer to the paper fed to the image forming unit by the paper feeding unit In an image forming apparatus comprising a fixing unit for fixing an image that has been fixed, and a paper discharge unit on which a sheet on which the image has been fixed is discharged and stacked.
An image forming apparatus comprising the paper discharge amount detection mechanism according to claim 1.

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