JP3215907B2 - Paper feeder for image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for an image recording apparatus such as a copying machine having a paper feed mechanism and a printer.

[0002]

2. Description of the Related Art In the above-mentioned image recording apparatus, recording paper as a recording material is fed one by one from a paper supply accommodating section which accommodates a large number of sheet-like recording papers such as a paper supply cassette and the like. A recording image is formed on the recording paper through the exposure, development, and transfer steps.

A toner image is formed on the photosensitive drum by the above-described exposure and development processes. In order to transfer the toner image from the photosensitive drum to a predetermined position on the recording paper in the transfer process, the toner image is fed from a paper feed cassette. The recording paper is temporarily stopped at a registration unit provided in the middle of a paper feeding path to a transfer unit near the photosensitive drum. Thereafter, the recording paper is fed from the registration unit to the transfer unit at a timing such that the toner image is transferred to a predetermined position on the recording paper by a control signal output from the image formation control unit.

For this reason, conventionally, an electromagnetic clutch is attached to each of a registration roller of a registration unit and an intermediate paper supply roller provided in a paper supply path from the paper supply cassette to the registration unit. In this case, the registration roller and the intermediate sheet feeding roller are "stopped" and "rotated" to control the sheet feeding timing of the recording sheet. Therefore, this device requires a complicated device configuration and control because a plurality of electromagnetic clutches are used.

On the other hand, the present applicant has developed a sheet feeding device in which a registration section is constituted by a registration roller and a registration shutter member. In this paper feeding device, the registration shutter member operates as a gate member that opens and closes the registration unit in response to a control signal from the image forming control unit. When the registration unit is "closed", the registration shutter member comes into contact with the leading edge of the recording paper to stop the recording paper and enter a standby state. When the registration unit is "open", the registration shutter member is retracted from the leading end of the recording paper, so that the recording paper is released from the standby state and the recording paper is fed from the registration unit to the transfer unit.

[0006]

In the above-described paper feeding apparatus, the registration roller and the intermediate paper feeding roller are always rotated regardless of whether the registration section is opened or closed. For this reason, the rotational force of the registration roller and the intermediate paper feed roller acts on the recording paper in the standby state where the leading end comes into contact with the resist shutter member, and the recording paper vibrates due to the rotational force, so-called paper squeal. There was a problem of generating abnormal vibration noise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple configuration of a registration roller and an intermediate sheet feeding roller and to prevent an abnormal vibration sound called paper squeal.

[0008]

According to the present invention, there is provided a paper feeder for an image recording apparatus, comprising: a feed roller for feeding a recording material from a recording material container; and a timing for sending a recording material to a transfer section near an image forming body. A registration sheet feeding unit having a registration shutter member for controlling the sheet feeding unit, and an intermediate conveyance unit positioned between the feed roller and the registration sheet feeding unit;
The intermediate conveyance unit includes a driving roller that is constantly rotating, a driven roller, and a pressing member that presses the driven roller against the driving roller, wherein the driven roller rotates integrally with the driven roller, and is attached to the shaft. It has a weight for preventing vibration.

[0009]

After investigating the cause of abnormal vibration of recording paper called paper squeal, the slippage between the drive roller and the recording material causes the driven roller and the bearing that supports the driven roller to resonate. I found it to be.

In order to prevent this phenomenon, it has been considered to use a roller made of a special material or to reduce the conveying force. However, in the former case, the cost is increased and the parts management becomes complicated. On the other hand, in the latter case, when thick card recording paper or OHP sheet is used, a conveyance failure occurs.

On the other hand, in the present invention, the intermediate conveying section having the above-mentioned weight for preventing vibration prevents abnormal vibration noise of the recording paper and has a sufficient conveying force for conveying the thick recording paper or the OHP sheet. As a result, feeding reliability was also improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view of an image recording apparatus (color printer) provided with a sheet feeding device according to the present invention. In the figure, a sheet cassette 3 containing a plurality of recording sheets P is detachably provided in a lower frame 1A of the image recording apparatus. A half-moon-shaped paper feed roller 2 for feeding recording paper P is provided on the paper feed cassette 3, and a push-up plate 4 for pressing the recording paper P against a separation claw 5 described later is provided in the paper feed cassette 3. I have. The recording paper P is separated and fed one by one from a paper feed cassette 3 by a paper feed roller 2 and a separation claw 5. The lower frame 1A further includes an intermediate paper feed roller 6 for the recording paper P.
Is provided to feed the recording paper P fed by the paper feed roller 2 upward. The intermediate paper feed roller 6 is provided between the paper feed cassette 3 and the curved reverse guide plate 7B.

The inverted recording paper P is guided to the registration rollers 9 by a guide plate 7C following the reverse guide plate 7B. A paper leading end detection sensor 8 is provided upstream of the registration roller 9 for feeding paper.
However, a registration shutter member 9A that operates as a gate member that opens and closes the registration unit in response to a control signal from the image forming control unit is provided on the downstream side of the sheet supply. information
Reference numeral 10 denotes a transfer belt for the recording paper P passing through the registration rollers 9
We will guide you in 11 directions. The transfer belt 11 is suspended around a pressing roller 12, a driving roller 13A, and a group of rollers 13B and 13C. The fixing device 15 is a device for fixing the image transferred onto the recording paper P, and includes a fixing heat roller, a pressure roller, and the like. The paper discharge roller 16 discharges the recording paper P from the fixing device 15, and the discharged recording paper P is used as a recording paper guide member 17 and a guide conveyance roller 18.
And is transported upward. The recording paper P conveyed upward by the conveyance rollers 18 is placed on a paper discharge tray 22 provided on substantially the entire upper portion of the upper frame 1B by a guide passage 20 formed in the upper frame 1B and paper discharge rollers 21. The recording paper P is discharged downward on the recording surface.

Next, a photosensitive drum 30 for image formation is provided at a substantially central portion of the upper frame 1B so as to be rotatable.
A charging electrode 31, a laser exposure scanning device 32, four sets of developing devices 33Y, 33M, 33C, 33K for accommodating color developers of the respective colors, from the upstream side of rotation along the peripheral surface of the photosensitive drum 30; A transfer means including a transfer electrode 11 and a transfer electrode 14 and a cleaning device 34 for transferring an image to the recording paper P and removing residual toner adhering to the surface of the photosensitive drum 30 are sequentially arranged.

Color toner and black toner are supplied to the developing devices 33Y, 33M, 33C and 33K from a toner replenishing device 35 fixed to a part of the upper frame 1B. Although only one set of the illustrated toner replenishing devices 35 is provided, four sets are provided side by side. For example, cyan, magenta, yellow, and black toners are supplied to the developing devices 33Y, 33M, 33C, and 33K.
It is configured to perform color development and black development.
Each new color toner is externally supplied to the toner replenishing device 35 from an opening / closing lid 36 capable of partially opening the upper frame 1B.

The upper frame 1B is configured so as to be able to open the conveyance path of the recording paper P around the support shaft 1C.
While the recording paper P is being fed and transported, it is in a defective transport state, and the recording paper P
Is not reached at least up to the fixing device 15, the upper frame 1B is opened around the support shaft 1C, and the recording paper P can be taken out.

FIG. 2 is a diagram of a feeder drive system. In the figure, a semi-lunar feed roller 2 is provided by a main motor 50 as a power source.
The driving force is transmitted to the driving registration roller 91 and the driving intermediate sheet feeding roller 61 via a toothed pulley and an intermediate gear group, respectively. The paper feed roller 2 is intermittently driven by the electromagnetic clutch 51. On the other hand, the driving registration roller 91 and the driving intermediate sheet feeding roller 61 are configured to be driven and rotated at all times.

FIG. 3 is an enlarged cross-sectional view of an intermediate conveyance section comprising the intermediate roller 6 and the reversing guide plate 7B in FIG. 1. FIG. 4 is a plan view showing the arrangement of a driving intermediate paper feeding roller 61 and a driven intermediate paper feeding roller 62. FIG.

As shown in FIG. 3, a pair of guide plates 71 and 72 constitute a reverse guide plate 7B. The guide plate 72 is fixed to the guide plate holding member 64, and by attaching the guide plate holding member 64 to a predetermined position in the apparatus, the guide plate 72 is adjacent to the guide plate 71, and the guide plate 71 and the guide plate 72 A reversing paper feed path is formed therebetween.

The drive intermediate paper feed roller 61 is located on the guide plate 71 side of the reverse paper feed path, is rotatably supported by a bearing fixed in the apparatus, and as described above, the main motor through the intermediate gear group. 50 driving forces are transmitted.

The driven intermediate paper feed roller 62 is located on the guide plate 72 side of the reverse paper feed path, and is attached to the guide plate holding member 64 via the elastic support member 63. That is, as shown in FIG. 4, the two driven intermediate paper feed rollers 62 are fixed to the driven shaft 62S, and the driven shaft 62S is rotatably supported by the two bearings 65. As shown in FIG. 3, the bearing 65 is attached to a free end 63F of the elastic support member 63, and a fixed end 63G of the elastic support member 63 is fixed to the guide plate holding member 64. With this configuration, the rotating system composed of the driven intermediate paper feed roller 62, the driven shaft 62S, and the bearing 65 forms a fixed end of the elastic support member 63.
It is supported elastically displaceable around 63G. FIG.
At the free end 63F of the elastic support member 63 indicated by the dotted line.
Indicates a position before being elastically displaced. Guide plate 72 described above
By attaching the guide plate holding member 64 with the fixed to the predetermined position in the apparatus, the driven intermediate paper supply roller 62 abuts on the drive intermediate paper supply roller 61, and the free end 63F of the elastic support member 63 is positioned at the position shown by the solid line. Displaces elastically up to This elastic support member
Due to the displacement of 63, the driven intermediate paper feeding roller 62 is pressed against the driving intermediate paper feeding roller 61.

As described above, by mounting the guide plate holding member 64 at a predetermined position in the apparatus, a reverse sheet feeding path is formed between the guide plate 71 and the guide plate 72, and the driven intermediate sheet feeding roller 62 is driven. The intermediate paper feed roller 61 is pressed against the intermediate paper feed roller 61 to form an intermediate paper feed unit. The driven intermediate feed roller 62 is a drive intermediate feed roller
When the recording paper P is rotated by being pressed against the intermediate feed roller 61, a conveyance force is generated between the driven intermediate paper feed roller 62 and the driving intermediate paper feed roller 61 in accordance with the pressure, and the recording paper P is moved from the reverse paper feed path by this conveyance force. It is transported to the resist section.

In the embodiment of FIG. 4, the weight 66 is an elastic support member.
It is divided into three parts symmetrically about the center 63 and is rotatably mounted on the driven shaft 62S. The weight 66 is configured to increase the inertial force of the rotating system including the driven intermediate sheet feeding roller 62 and the driven shaft 62S. The weight 66 can be fixedly mounted on the driven shaft 62S, but it is more effective to rotatably mount the weight 66 in consideration of vibration responsiveness. Also,
It is more preferable to mount it rotatably also from the viewpoint of assembly.

The recording paper P used in the above-described paper feeding mechanism of the present invention is not limited to a standard copy paper, but may be a thick recording paper, an OHP sheet, or the like.

FIG. 5 shows a driven intermediate paper feed roller according to the pressing force.
FIG. 9 is a diagram illustrating the results of an experiment conducted to investigate the effect of a conveying force generated between a roller 62 and a driving intermediate paper feed roller 61 on various paper qualities. In the figure, the horizontal axis represents paper quality, A is 16 pounds paper, B
Indicates 20 pounds paper, C indicates 28 pounds paper, D indicates 36 pounds paper, and E indicates 5 mil OHT. The vertical axis represents the conveying force (gf). The shaded area is the area where the trouble was recognized, and the shaded area in the area where the conveyance force was weak was the resist shutter member 9A due to insufficient conveyance force.
The toner image was not transferred to a predetermined position on the recording paper because a delay was observed in the conveyance after "opening". The shaded area in the area where the conveying force is strong is the resist shutter member 9A due to the excessive conveying force.
"Closed" caused wrinkles due to buckling of the standby recording paper. For example, in the case of A 16 pound paper, the conveyance force is about 180 (g
Below f), a transport delay occurred, and wrinkles occurred above a transport force of about 600 (gf). Therefore, the transfer force is about 180 (gf) to 6
The range of 00 (gf) is the area of the appropriate conveying force for the 16 pound paper of A.

As shown in FIG. 5, it is preferable to select a conveying force in a range from 300 (gf) to 600 (gf) in consideration of an appropriate conveying force for all paper qualities.

FIG. 6 is a diagram showing the relationship between the weight of the weight and the region where the abnormal vibration sound is generated, obtained in a paper feed test using a recording sheet of 5 mil OHT, which is most likely to generate the abnormal vibration sound.
The vertical axis indicates the conveying force (gf) of the intermediate sheet feeding unit, and the horizontal axis indicates the weight (gf) of the weight. From this figure, it can be seen that as the transfer force CF (gf) becomes stronger, the weight W (g
It is necessary to increase f), and specifically, it is sufficient that the weight satisfies W> 112−0.6 CF + CF ^{2 −} (1). On the other hand, when the transfer force is weak, the weight of the weight for preventing abnormal vibration noise can be reduced, but as described above, the transfer is delayed in the region where the transfer force is weak.
In order to prevent this transport delay, it is necessary to secure an appropriate transport force, and it is necessary to determine the weight of the weight so as to satisfy the above equation (1) according to the appropriate transport force.

In the sheet feeding mechanism of the present invention described above, as an example, the conveying force of the intermediate sheet feeding section is set to 500 (gf), and the vibration isolating weight 66 having a weight of 25 (gf) is driven so as to satisfy the above relational expression.
A paper feed test was performed by freely rotating the 62S.

As described above, the recording paper is separated one by one from the paper feed cassette 3 by the paper feed roller 2 and the separation claw 5 and fed to the intermediate paper feed unit. It was conveyed to the resist section via the reversing guide plate 7B by 61 and 62. At the registration section, the leading end of the recording paper was brought into contact with the registration shutter member 9A and stopped, and the recording paper was put into a standby state. Even in this standby state, the rotation of the registration roller 9 and the intermediate paper feed rollers 61 and 62 is continued, and the recording paper is slightly affected by the rotation in the first half and the second half thereof. Since the rotating system of the driven intermediate paper feed roller 62 supported by the support member 63 is added with inertia by the weight 66, no resonance phenomenon occurred and no abnormal sound was generated.

Thereafter, when the registration shutter member 9A retreats from the leading end of the recording paper and is opened when the registration shutter member 9A is synchronized with the timing of toner image formation, the recording paper is conveyed to the transfer unit without causing a conveyance delay, and is moved to the predetermined position. The toner image has been transferred. A, B, C, D,
And E were used, respectively, but image formation was carried out without occurrence of transport delay, buckling and abnormal noise.

The weight 66 can be attached to a registration roller. However, when a curved reversing sheet feeding path is formed between the intermediate sheet feeding roller 6 and the registration roller 9 as in this embodiment, the driven intermediate sheet feeding roller 62 is used. Preferably, it is mounted on

FIGS. 7A and 7B show another embodiment of the intermediate sheet feeding section. That is, in the embodiment of FIG. 4, a leaf spring is used as the elastic support member. However, the elastic support member of the present invention is not limited to a leaf spring. Any member that presses against 61 can be applied. For example, FIG.
As shown in FIG. 7A and FIG. 7B, a coil spring 69 can be used. Comparing the leaf spring and the coil spring, the leaf spring is preferable because it can easily maintain an appropriate elastic force and can easily control the displacement direction.

[0034]

According to the structure described above, the following effects can be obtained.

As described above, the effect of claim 1 is that the driven intermediate sheet feeding roller of the intermediate conveyance section is configured to have a weight for preventing vibration, so that abnormal vibration noise of the recording sheet can be prevented. . According to the second aspect of the present invention, the driven roller is pressed against the drive roller via the bearing by the elastic support member. Therefore, in addition to the effect of the first aspect, the intermediate sheet feeding section can be simply configured.

Further, the effect of the third aspect is that the range of the sheet feeding and transporting force is defined. Therefore, in addition to the effect of the first aspect, a sufficient conveying force for conveying the thick recording paper or the OHP sheet is secured. Transmission reliability was improved.

Furthermore, the effect of the fourth aspect is that the weight of the vibration-proofing weight with respect to the paper feeding traveling force is specified, so that the abnormal vibration noise of the recording paper can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an image recording apparatus provided with a sheet feeding device according to the present invention.

FIG. 2 is a drive system diagram of a feeding unit.

FIG. 3 is an enlarged cross-sectional view of an intermediate conveyance unit.

FIG. 4 is a plan view showing an arrangement of a driving intermediate paper feeding roller 61 and a driven intermediate paper feeding roller 62.

FIG. 5 is a diagram showing the results of an experiment conducted to investigate the effect of a conveying force on various paper qualities.

FIG. 6 is a diagram showing the relationship between the weight of a weight and an abnormal vibration sound generation region.

FIG. 7 is a diagram illustrating another embodiment of the intermediate sheet feeding unit.

[Explanation of symbols]

 1A Lower Frame 1B Upper Frame 9 Registration Roller 61 Drive Intermediate Feed Roller 62 Follower Intermediate Feed Roller 63 Elastic Support Member 64 Guide Plate Holding Member 65 Bearing 66 Weight

Claims (4)

(57) [Claims] A feed roller that feeds a recording material from a recording material container, a registration paper feeding unit that feeds the recording material to a transfer unit near an image forming body, and an intermediate conveyance unit that is located between the feeding roller and the registration paper feeding unit. Having a driving roller that the intermediate conveyance unit constantly rotates, a driven roller, and a pressing member that presses the driven roller against the driving roller, wherein the driven roller rotates integrally with the driven roller, and A sheet feeder for an image recording apparatus, having a weight for preventing vibration attached to the shaft. 2. The pressing member is an elastic supporting member, a bearing of the driven roller is supported by the elastic supporting member so as to be elastically displaceable, and the driven roller is supported by the elastic supporting member via the bearing. 2. The sheet feeding device for an image recording apparatus according to claim 1, wherein the sheet feeding device is pressed by a driving roller. 3. The range of the sheet feeding force of the intermediate feeding section is 18
3. The sheet feeding device of the image recording apparatus according to claim 1, wherein the value is not less than 0 (gf) and not more than 600 (gf). 4. The weight of the vibration preventing weight is W (g).
f), when the paper feed force of the intermediate feed unit is CF (gf),
4. The sheet feeder according to claim 1, wherein the vibration preventing weight has a weight that satisfies the following expression. 5. W> 112−0.6CF + CF ²