JP2002211773A - Paper feeder, recording device and d-type paper feeding roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder and a recording device provided with this capable of stably feeding paper without influence from wear of a paper feeding roller and even when using high image quality printing paper. SOLUTION: The D-type paper feeding roller shaped like a D shape from a side view feeding a recording medium into the recording device has a pickup area abutting on the recording medium in feeding to start sending of the recording medium, and a feeding area abutting on the recording medium consecutively to the pickup area to send the recording medium. A length LD of the feeding area is set longer than an absolute minimum paper feeding distance L necessary for feeding the recording medium, or a frictional force with the recording medium in the pickup area is set so it is an absolute minimum frictional force or more within a range of a maximum possible number of paper feeding times of the paper feeder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding recording media stacked by a rotary sheet feeding roller having a substantially D-shape in side view, one sheet at a time, from the highest one, and the sheet feeding apparatus. The present invention relates to a recording device including:

[0002]

2. Description of the Related Art In a recording apparatus such as a printer, a facsimile, and a copying machine, a sheet-shaped recording medium (plain paper, coated paper, OHP sheet, glossy paper, glossy film, etc.) is supplied and conveyed to form an image. After discharging, a configuration is generally adopted. This type of recording apparatus generally includes a paper feed roller for feeding a recording medium into the apparatus, a paper feed roller for transporting the recording medium supplied by the roller (also referred to as a “transport roller”), The image forming apparatus is provided with conveying means such as a paper discharge roller for discharging the recording medium on which the image is formed to the outside of the apparatus.

FIG. 1 shows a general configuration of a paper feeder provided with the above-mentioned paper feed roller. The sheet feeding device SF has a pair of sheet feeding roller units 120 and 120 ′ attached to a sheet feeding roller shaft 110, and a hopper 130 rotatably attached to a frame (not shown). ing.

[0006] As shown in FIG.
During standby, the linear portion 121b of the paper feed roller 121 is in a state of facing the paper (that is, the recording medium),
The paper feed roller 121 is not in contact with the paper. At the time of the sheet feeding operation, the sheet feeding roller 121 rotates clockwise in the drawing, and the arc portion 121a contacts the uppermost sheet P1 of the sheets, so that the sheet is directed toward the separation pad 150. Sent. At this time, the sheet P2 is fed together with the sheet P1 because the next sheet P2 is attracted to the sheet P1 by the action of static electricity or a frictional force acts between the sheet P1 and the sheet P2. May be used. However, the paper P2 is
When the leading end of the sheet abuts on the separation pad 150, the movement is hindered, and the sheet can be primarily separated from the sheet P1.

The arc section 121a of the paper feed roller 121
The frictional force between the sheet P1 and the sheet is f1, the sheet P1 and the separation pad 1
Assuming that the frictional force between the sheet P1 and the sheet P2 is f2, and the frictional force between the sheet P1 and the sheet P2 is f3, the sheet feed roller 121 and the separation pad 15 are set so that the relationship of f1>f2> f3 is established.
0, the sheet P1 and the sheet P2 are sandwiched between the arc portion 121a of the sheet feeding roller 121 and the separation pad 150 as the sheet feeding roller 121 rotates. The movement is hindered by the frictional force between the sheet P1 and the sheet P1, and the sheet P2 is secondarily separated from the sheet P1, and only the sheet P1 is fed.

As described above, in the paper feeder SF of FIG. 1, if the paper feed roller 121 is a circular paper feed roller 121, it is always in pressure contact with the separation pad 150. The problem of easy wear is overcome by using a D-shaped paper feed roller 121 having a D-shape in side view. However, when the paper feeder reaches a certain amount of use (the number of papers to be conveyed), the frictional force is reduced due to abrasion of the elastic member on the surface of the paper feed roller 121, fine paper powder is adhered, and further, coated paper or the like is used. The adhesion of a gap agent or a lubricant used for the purpose of preventing adhesion and imparting slipperiness reduces the frictional force between the paper feed roller 121 and the recording medium, lowers the ability to feed the recording medium, It is known that problems such as feeds and paper jams occur.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeder which is hardly affected by abrasion of a paper feed roller and which can stably feed paper even when high quality printing paper is used. To provide a recording device.

[0008]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus for rotating a sheet feeding apparatus to rotate the sheet feeding apparatus so as to supply the recording medium into the recording apparatus. A sheet feeding device including a D-type feeding roller having a substantially D-shape in side view for feeding a recording medium into the recording device by a frictional force at the time of the contact, wherein the D-type feeding roller includes Starting from a corner from the end of the linear portion to the beginning of the arc when viewed in the rotation direction, the recording medium is provided over a predetermined range in the rotation direction, and comes into contact with the recording medium at the time of feeding to start feeding of the recording medium. a pickup region, in contact with the recording medium subsequent to the pick-up region are those having a feeding area and sends the recording medium, the length of the fed-feeding region (L _D)
Is set to be longer than the minimum necessary feeding distance (L) required for feeding the recording medium. Here, the "minimum necessary feeding distance" differs depending on the size and type of the recording apparatus, but generally, the initial feeding distance at which the corner of the paper feed roller first comes into contact with the recording medium for feeding. It can be defined as a distance from the contact position to a contact center point (nip point) formed by a pair of paper feed rollers provided downstream of the recording medium conveyance path. According to this feature, by providing the pickup area over a predetermined range, even in the pickup area, even if the frictional force of the initial contact portion with respect to the sheet is reduced due to continuous use and the feeding force is insufficient, In the position immediately following that, the frictional force is still kept high. Then, the length of the pickup area (L
The length of the feeding area following the _P) (L _D) is, it is set longer than the minimum required feed distance required for feeding the recording medium (L), intensive wear and paper dust The adhesion force lowers the frictional force at the initial contact area in the pickup area, and ensures that a sufficient amount of paper is fed in the feed area even if the paper pickup area moves back, reducing the effects of wear and adhesion of paper dust. It is difficult to receive paper and paper jams.

According to a second aspect of the present invention, in the first aspect, the relationship of L _D -L> 0 is maintained within the range of the maximum number of feeds of the sheet feeding device. Features. Here, the maximum number of feeds that can be performed by the paper feeder is the number of papers that is set as a measure of the durability of the paper feeder, and varies depending on the paper feeder and the type of recording medium used. Is designed with tens of thousands to 100,000 sheets in mind. It is also known that when high-quality printing paper such as super fine paper, photo print paper, glossy paper, etc. is frequently used as a recording medium, the maximum number of sheets that can be fed is lower than that of plain paper. . According to this feature, the relationship of L _D -L> 0 can be maintained within the range of the maximum number of feeds of the sheet feeding device, so that a satisfactory sheet feeding operation can be expected until the end of the life of the device. In addition, even in a usage mode in which high-quality printing paper is frequently used, paper powder is concentrated and adheres,
Since the paper is fed in the feeding area outside the pickup area where the paper feeding force decreases, it is hardly affected by the adhesion of the paper powder,
It is possible to extend the life of the sheet feeding device.

According to a third aspect of the present invention, in order to supply a recording medium into the recording apparatus, the recording medium rotates and comes into contact with the recording medium, and the recording medium is moved by the frictional force at the time of contact. A sheet feeding device having a substantially D-shaped D-type sheet feeding roller for feeding into a recording apparatus, wherein the D-type sheet feeding roller has an arc from the end of the linear portion when viewed in the rotation direction of the roller. A pickup area is provided over a predetermined range in the rotation direction, starting from a corner toward the beginning of the section, and comes into contact with the recording medium at the time of feeding and starts feeding of the recording medium. A feeding area for contacting the recording medium and feeding the recording medium, wherein the frictional force between the pickup area and the recording medium is within a range of the maximum number of feeds of the sheet feeding device, and a minimum required friction Force is set to The features. Here, the minimum feeding frictional force means a minimum frictional force between the D-type paper feed roller and the recording medium when starting the recording medium feeding operation. Although it exceeds the frictional force, especially in the pickup area, the decrease in the frictional force is concentrated due to abrasion, adhesion of paper powder, and the like, and when the frictional force falls below the minimum feeding frictional force, non-feeding occurs. According to this feature, the frictional force with the recording medium in the pickup area is set so as to be equal to or more than the minimum necessary frictional force within the range of the maximum possible number of feedings of the sheet feeding device. In this case, a good paper feeding state can be maintained without causing non-feeding.

According to a fourth aspect of the present invention, at least the pickup area is formed of a material having a large friction coefficient with respect to a recording medium. According to this feature, since at least the pickup area is formed of a material having a large friction coefficient with respect to the recording medium, it is possible to increase the initial friction force of the pickup area with respect to the recording medium in which the reduction of the friction force is concentrated. Therefore, even if the frictional force in the pickup area is reduced due to the progress of abrasion and the adhesion of paper dust, the frictional force that is equal to or more than the minimum necessary frictional force can be maintained within the range of the maximum number of feeds. A good paper feeding state can be maintained without causing the problem.

Further, the invention of a paper feeder according to a fifth aspect is characterized in that, in the third aspect, at least the pickup area is formed of a material having high wear resistance. According to this feature, since at least the pickup region is formed of a material having high wear resistance, the frictional force is hardly reduced particularly due to the progress of wear, and the minimum necessary frictional force can be maintained.

According to a sixth aspect of the present invention, in the third aspect, the pressing force on the recording medium in the pickup area is larger than the pressing force of the recording medium in the feeding area. It is characterized by the following. Here, as an example of a means for increasing the pressing force on the recording medium in the pickup area, a configuration is possible in which the thickness of the elastic body in the pickup area is larger than that in the feeding area. According to this feature, the pressing force on the recording medium in the pickup area is made larger than the pressing force on the recording medium in the feeding area, so that the initial frictional force on the recording medium in the pickup area can be increased,
Even if the frictional force in the pickup area decreases due to the progress of wear or the adhesion of paper dust, the minimum necessary frictional force can be maintained.

According to a seventh aspect of the present invention, there is provided a recording apparatus including the sheet feeding device according to any one of the first to sixth aspects. According to this feature, in the recording apparatus, it is possible to obtain the same operation and effects as those of the sheet feeding apparatus according to any one of the first to sixth aspects.

[0015] Further, the invention of a recording apparatus according to claim 8 is as follows.
8. The printing apparatus according to claim 7, wherein a paper detecting unit is provided in a recording medium conveyance path between the paper feeding roller and a paper feeding roller that further conveys the fed recording medium toward a recording unit. And Here, as the paper detecting means, a paper detecting means having a known configuration, for example, an optical paper detecting means which is operated by the feeding force of the recording medium can be used. According to this feature, the following effects can be obtained. With the continuous use of the paper feeding device, the actual paper pick-up portion in the pickup area moves, so that the paper feed amount with respect to the rotation amount of the paper feed roller fluctuates. However, by detecting that the leading edge of the paper passes through the position of the paper detecting means, the paper feed amount can be controlled in a state where the leading edge of the paper conveyed by the paper feeding mechanism is grasped from the detected position as a starting point. Therefore, it is possible to eliminate the influence of the movement of the sheet pickup portion.

According to a ninth aspect of the present invention, there is provided a D-type paper feed roller, which is incorporated in a paper feeder to supply a print medium into the print apparatus, and rotates and comes into contact with the print medium. A substantially D-shaped D-type paper feed roller for feeding a recording medium into the recording apparatus by the frictional force of the roller. A pickup area is provided over a predetermined range in the rotation direction, starting from a corner portion extending from the corner to the start end of the arc portion, and a pickup area which comes into contact with the recording medium at the time of feeding and starts feeding of the recording medium. those having a feeding area and sends the recording medium in contact with subsequent recording medium and those, the length of the fed-feeding region (L _D), feeding the minimum required supply required for feeding the recording medium It is characterized in that it is set longer than the distance (L). According to this feature, the same function and effect as the first aspect can be obtained.

According to a tenth aspect of the present invention, there is provided a D-type paper feeding roller, which is incorporated in a paper feeding device for supplying a recording medium into the recording device, and rotates and comes into contact with the recording medium. A substantially D-shaped D-type paper feed roller for feeding a recording medium into the recording apparatus by the frictional force of the roller. A pickup area is provided over a predetermined range in the rotation direction, starting from a corner portion extending from the corner to the start end of the arc portion, and a pickup area which comes into contact with the recording medium at the time of feeding and starts feeding of the recording medium. Having a feed area for sending the recording medium in contact with the recording medium,
Friction force with the recording medium in the pickup area,
It is characterized in that it is set so as to be equal to or more than the minimum necessary frictional force within the range of the maximum number of feeds of the sheet feeding device. According to this feature, the same function and effect as the third aspect can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment. First, the overall configuration of the sheet feeding device SF will be described based on a partial side view (partially transparent) showing the printer shown in FIG. As shown in FIG. 1, this sheet feeding device SF
Has a pair of paper feed roller units 120 and 120 'attached to the paper feed roller shaft 110, and a hopper 130 rotatably mounted on a frame (not shown).

In FIG. 1, reference numeral 121 denotes a paper feed roller which is a component of the paper feed roller units 120 and 120 '. The paper feed roller 121 has an arc portion 121a and a linear portion 1a.
21b. When viewed in the rotation direction of the paper feed roller 121, the corner from the end of the linear portion 121b to the start of the circular arc portion 121a acts as a feed action start corner 121c. Further, at least the arc portion 1 of the sheet feeding roller 121 is used.
The surface of 21a and the surface of the straight portion 121b are formed of an elastic body (for example, rubber) of a high friction material. Although not shown, the paper feed roller shaft 110 is driven to rotate just one rotation at the time of paper feed operation by an electric motor as a driving means via a gear fixed to the shaft end.

The hopper 130 is rotatably mounted on a frame (not shown) by a shaft 132. Reference numeral 137 denotes a paper feed tray, and the paper feed tray 1
37 is attached to the printer. On the hopper 130 and the paper feed tray 137, a plurality of sheets P
Are set in a laminated state. The set sheet P is supported and aligned by its leading end contacting the back surface (support surface) 152 of the separation pad holder 151 described later.

Reference numeral 140 denotes a paper feed roller unit 120,
A hopper spring (compression spring) 133 is provided between the sub-frame 140 and the tip of the hopper 130. The hopper 130 is moved by the hopper spring 133. In FIG. 1, the sheet P is constantly urged in a clockwise direction, that is, in a direction in which the sheet P comes into contact with the sheet feeding roller 121. However, the rotation is restricted by the cam followers provided at both ends of the hopper 130 abutting the hopper cam 135 (see FIG. 2) fixed to the paper feed roller shaft 110.

The separation pad 150 is fixed to the separation pad holder 151. The separation pad 150 is made of a material (for example, a material such as cork) whose friction coefficient with respect to the paper P is smaller than the friction coefficient of the paper feed roller 121. Each of the friction coefficients is made of a material having a friction coefficient larger than the friction coefficient between sheets. That is, if the friction coefficient between the paper feed roller 121 and the paper is μ1, the friction coefficient between the separation pad 150 and the paper is μ2, and the friction coefficient between the papers is μ3, μ1>μ2> μ3.

The separation pad holder 151 includes a pad support 153 (FIG. 2) to which the separation pad 150 is fixed, a support surface (rear surface) 152 at the leading end of the sheet, and an arm 154 formed integrally therewith. And a rear end of the arm 154 is rotatably attached to the sub-frame 140 by a shaft 155. The separation pad holder 15 is formed by a pad spring 156 provided between the lower surface of the pad support 153 and the subframe 140.
1 is a clockwise direction in FIG.
0 is constantly urged in the direction in which it contacts the paper feed roller 121.

Such a paper feeder SF is incorporated in a printer as shown in FIG. In FIG.
Reference numeral 3 denotes a pair of conveying rollers for conveying the paper, reference numeral 4 denotes a recording head for recording on the paper, reference numerals 5 and 6 denote a pair of discharge rollers for discharging the recorded paper, reference numeral 7 denotes a paper detecting means, and reference numerals 8a and 8
b is a paper guide. Reference numeral L denotes a minimum required feeding distance in the printer, and here, an initial contact where a corner portion (feed action start corner portion) 121c of the feeding roller 121 first contacts a recording medium for feeding. The distance from the position to the contact center point (nip point) formed by the pair of paper feed rollers 2 and 3 provided downstream of the recording medium conveyance path. The hopper 130 is inclined as shown, and a plurality of sheets of paper P are set thereon in a stacked state.

Next, the operation of the above-described paper feeder will be described. During standby, the hopper cam 135
The hopper 130 has been pushed down. The paper feed roller 121 is in a state where the linear portion 121b faces the paper P, and the paper feed roller 121 is not in contact with the paper P. The separation pad holder 151 (ie,
The separation pad 150) is moved by a pad spring 156 in FIG.
, The rotation is restricted by contact with a pin (not shown), and is stopped at the position shown in FIG. Therefore, the urging force of the pad spring 156 does not act on the idle roller 160. Further, at this time, the separation pad 150 is located in the rotation trajectory of the arc portion 121a of the paper feed roller 121. The idle roller 160 is driven by the biasing force of the roller spring.
Is in contact with

Next, the operation during paper feeding will be described. (1) In FIG. 2, the paper feed roller shaft 110 starts rotating clockwise. Therefore, the paper feed roller 121, the bush 142, and the hopper cam 135 also start rotating.

(2) As shown in FIG.
10 together with the feed roller 121 and the hopper cam 13
5 rotates by a predetermined angle, and the hopper cam 135 leaves the cam follower 134 of the hopper 130. This allows
Cam follower 1 for hopper cam 135 and hopper 130
34 is released, the hopper 130 is momentarily pushed up by the hopper spring 133 (FIG. 1),
The sheet P is also pushed up, and the uppermost sheet P1 is pressed against the arc portion 121a of the sheet feeding roller 121. At this time, the paper feed roller 121 has its linear portion 1 viewed in the rotational direction.
From the end of 21b, the corner of the starting end of the arc portion 121a (the feed action start corner) 121c contacts the uppermost sheet P1.

(3) Further, as the paper feed roller shaft 110 continues to rotate, the arc portion 121 of the paper feed roller 121 is
The sheet P1 is sent toward the separation pad 150 by rotating while contacting the uppermost sheet P1 with the sheet P1. At this time, the next paper P2 is attracted to the paper P1 by the action of static electricity,
1 and the paper P2 exert a frictional force,
The sheet P2 may be sent together with the sheet P1, but the movement of the sheet P2 is hindered by the leading end of the sheet P2 hitting the separation pad 150, and the sheet P2 may be separated from the sheet P1 temporarily.

(4) Further, as the paper feed roller shaft 110 continues to rotate, the arc portion 121 of the paper feed roller 121 is rotated.
a presses the separation pad 150 via the uppermost sheet P1. As a result, the separation pad 150 is pushed down, and the urging force of the pad spring 156 causes the paper feed roller 12
The uppermost sheet P1 is clamped between the first circular arc portion 121a. That is, the sheet P <b> 1 is sent while being pressed between the sheet feeding roller 121 and the separation pad 150. At this time, the next sheet P2 may be sent together with the sheet P1, but the friction coefficient between the sheet feeding roller 121 and the sheet is μ1, the friction coefficient between the separation pad 150 and the sheet is μ2, and the sheet Assuming that the friction coefficient between is μ3, μ1
>Μ2> μ3, so that the paper P1 and the paper P2 are both
When the sheet P2 is sandwiched between the arc portion 121a and the separation pad 150, the movement of the sheet P2 is hindered by the frictional force between the separation pad 150 and the sheet P2, and the sheet P2 is secondarily separated from the sheet P1. , Only the sheet P1 is fed. At this time, the cam follower 166 of the idle roller holder (not shown) rides on the arc surface 123b of the cam 123 formed on the bush 142. As a result, the idle roller 160 moves upward and is separated from the separation pad 150. That is, the leading edge of the sheet P1 to be fed is
When passing between the roller 50 and the idle roller 160,
The idle roller 160 has already been separated from the separation pad 150. Note that the leading end of the uppermost sheet P1 has not yet reached the contact portion T (see FIG. 2) between the idle roller 160 and the separation pad 150.

(5) As the paper feed roller shaft 110 continues to rotate, the paper P1 is further fed in a state where the paper P1 is nipped by the paper feed roller 121 and the separation pad 150.
At this point, the cam follower 16 of the idle roller holder
6 is located near the end of the inner arc surface 123b of the cam 123.

(6) Further, as the paper feed roller shaft 110 continues to rotate, the paper P1 is further fed while being pressed between the paper feed roller 121 and the separation pad 150. At this time, the cam follower 166 slides down the other inclined surface 123c of the cam 123, and the idle roller 160 comes into contact with the separation pad 150. However, at this time, the arc 12
1a shows a state where the separation pad 150 is pressed via the sheet P1. That is, the arc portion 121 of the paper feed roller 121
Before the contact of the separation pad 150 with the separation pad 150 via the sheet P1 is released, the idle roller 160
Abut. In addition, the hopper 130 is a hopper cam 1
Depressed at 35.

(7) Further, the feed roller shaft 110 rotates (just one rotation), and the hopper 130
At 5, it is completely depressed and returns to the standby state (FIG. 1). However, at this point, the sheet P1 is not completely removed from the sheet feeding device. Therefore, until the trailing edge of the sheet P1 passes through the contact portion T between the separation pad 150 and the idle roller 160, the sheet P1 is loaded in the contact portion T (pulled rearward). 1 are conveyed by the conveying rollers 2 and 3 shown in FIG. In this case, since the idle roller 160 is pressing the paper P1 between the separation pad 150, the paper P1
The next paper P2 separated from the paper P1 is going to descend by its own weight, or is attracted to the paper P1 by the action of static electricity, or is sent together with the paper P1 by frictional force with the paper P1. Even this is stationary.

(8) After the trailing end of the sheet P1 fed and conveyed as described above comes off the sheet feeding device SF, the sheet feeding operation is performed again as necessary.

As described above, in the paper feeder SF using the D-type paper feed roller 121, when viewed in the rotation direction of the D-type paper feed roller 121, the end of the linear portion 121b and the arc-shaped portion 121a. Feeding action start corner 12 to the start end
1c, it comes into contact with the recording medium, takes in the paper on the hopper 130, and sends it. In other words, the D-type paper feed roller 121 is provided over a predetermined range in the rotation direction of the paper feed roller 121 starting from the feed action start corner 121c, and comes into contact with the recording medium P at the time of feeding, and the frictional force is increased. (Hereinafter referred to as "pickup area 200" in the present invention) and an arc for contacting the recording medium P successively with the pickup area 200 and feeding the recording medium P by frictional force. Area (referred to as “feeding area 300” in the present invention) (see FIG. 3 described later).

According to the knowledge obtained by the present inventor, D
Pickup area 20 in mold feed roller 121
0 initial contact part (feed action start corner part 121c)
Tends to concentrate wear. In particular, the recording medium P loaded on the rotating D-type paper feed roller 121 and the hopper 130 that rotates with the urging force of the hopper spring 133.
Is repeated at the feeding action start corner portion 121c in the pickup area 200, so that the wear of this portion progresses faster than other portions of the feed roller 121. This contributes to lowering the frictional force at the portion, and furthermore, causes non-feeding while continuing to be used.

Although there is not much problem with plain paper,
When the paper feeding device SF is applied to a printer and high quality printing paper provided with a coat layer such as photo print paper is handled, the paper dust and the coating material start the feeding operation of the D-type paper feeding roller 121. The D-type feed roller 121 adheres to a surface portion near the corner portion 121c (which is considered to overlap with the surface portion illustrated as the pickup area 200 in FIG. 3), and the D-type paper feed roller 121 slips due to the attached paper dust. Paper feed force decreases.

As described above, the occurrence of non-feed is caused by D
Rather than a reduction in the frictional force of the entire mold feeding roller 121, the feed action start corner portion 1 in the pickup area 200
It was found that the local decrease in frictional force at 21c was the main cause. In other words, a slip occurs between the D-type paper feed roller 121 and the recording medium at the start of the feeding operation due to a decrease in the frictional force of the feeding action start corner 121c in the pickup area 200 (as a result, conceptually, Means that the paper pick-up portion described later retreats backward from the feed action start corner portion 121c, which is the initial contact portion, as viewed in the direction of rotation of the roller.) It is thought that.

Therefore, in order to prevent the occurrence of non-feed, in anticipation of a decrease in the frictional force in the pickup area 200, the pickup area 200 in which the frictional force is reduced is set outside the range of the minimum necessary feeding distance (L). Or at least the pickup area 200
By increasing the frictional force of the sheet feeding device SF, when the maximum feedable sheet number of the sheet feeding device SF is fed, the pickup area 20
It is effective that the frictional force of 0 can maintain the minimum required frictional force.

Based on the above, a first embodiment of the present invention will be described with reference to FIG. FIGS. 3A and 3B are side views conceptually showing a D-type paper feed roller. Here, in the D-type paper feed roller 121, a pickup area 200 [] on the circular arc portion 121a having a spread in a certain range starting from a feed action starting corner portion 121c from the end of the linear portion 121b to the start end of the circular portion 121a. FIGS. 3 (a) its length, and] shown as a code _{L P} in (b), assuming a feed region 300 of the arc portion 121a subsequent thereto. At the time of product shipment, the paper pickup portion 201 indicated by a black point in FIG. 3A substantially coincides with the feeding action start corner portion 121c in the pickup area 200. With use, the frictional force of the feed action start corner portion 121c gradually decreases. As a result, the sheet pickup portion 201 gradually retreats to a portion having a high frictional force immediately after the feed action start corner portion 121c as viewed in the rotation direction of the D-type sheet supply roller 121. Then, at the stage where the maximum number of sheets that can be fed is fed, the sheet pickup portion 201 moves to the rear end of the pickup area 200 (FIG. 3B). However, even in this state, the length (L _D ) of the feeding area 300 is set longer than the minimum necessary feeding distance (L) necessary for feeding the recording medium in the present invention. In the feeding area 300, a sufficient feeding distance can be secured to reach the leading end of the sheet to the pair of sheet feeding rollers 2 and 3, so that non-feed does not occur. The length of the feed region 300 (L _D), the type of the recording apparatus incorporating the sheet feeding apparatus SF (i.e., the length of the minimum feed required distance L) and to the maximum feed number of sheets of the paper feeding apparatus SF Correspondingly, it is preferred that L _D is set so as not to fall below the L. As a specific means for setting L _D so as not to be lower than L, for example, it is possible to increase the cross-sectional radius of the D-type paper supply roller 121.

Further, as shown in FIG. 1, in a recording apparatus provided with the sheet feeding device SF of the present invention, a sheet feeding roller 121 is provided.
And a paper detecting means 7 provided in the transport path of the recording medium P between the paper feed rollers 2 and 3 for further transporting the recording medium fed by the paper feeding device SF toward the recording section. Is preferred. This is for the following reason.

That is, as described above, the continuous use of the sheet feeding device SF causes the sheet pickup portion 201 in the pickup area 200 to retreat, so that the feed amount of the sheet P with respect to the rotation amount of the sheet feeding roller 121 gradually increases. Will fluctuate. However, if the paper detection means 7 is provided in the transport path so that the leading end of the paper can be detected to pass through the position of the paper detection means 7, the detection position is used as a starting point and the paper feed roller pair is thereafter used. Since the sheet feed amount can be controlled in a state where the leading end position of the sheet P conveyed by the sheet feed mechanism such as 2, 3 is grasped, it is possible to eliminate the influence of the movement of the sheet pick-up portion 201.

FIGS. 4 to 6 are views each showing another embodiment of the present invention, and are side views conceptually showing the D-type paper feed roller 121 similarly to FIG. Here, in the D-type paper feed roller 121, assuming the pickup area 200 on the arc portion 121a in advance, the frictional force of the pickup area 200 is set to the minimum required friction within the range of the maximum feedable number of the sheet feeding device SF. It is designed not to fall below the force.

That is, for the elastic layer (for example, rubber) 121d covering the outer surface of the D-type paper feed roller 121, the initial frictional force is set high by changing the material and layer thickness of the pickup area 200. (Fig. 4,
By making it harder to wear (FIG. 6) (FIG. 5), the frictional force does not fall below the minimum required frictional force.

In FIG. 4, in order to increase the frictional force in the pickup area 200, at least the pickup area 20 is used.
0 is formed of a material having a large coefficient of friction with respect to the recording medium. Here, the material having a large friction coefficient can be obtained, for example, by blending a known additive into a coated elastic body such as rubber. Further, as another means for increasing the frictional force of the pickup area 200, for example, providing a fine projection shape on the surface of the pickup area 200 may be mentioned. FIG. 5 shows at least the pickup area 200.
Is formed of a material having high wear resistance. A material having high abrasion resistance can be obtained by, for example, changing the vulcanization conditions of a coated elastic body such as rubber or blending a known additive. FIG. 6 shows that the thickness of the elastic body in the pickup area 200 is changed in another part of the sheet feeding roller 121 (the feeding area 3).
The thickness of the recording medium is made larger than that of the recording medium in the feeding area 300 by forming the layer with a greater thickness than that of the recording medium or the straight portion 121b). By doing so, the initial frictional force of the pickup area 200 of the D-type paper feed roller against the recording medium is increased,
The frictional force does not fall below the minimum required frictional force within the range of the maximum number of sheets that can be fed.

In the present invention, it is needless to say that the embodiments shown in FIGS. 3 to 6 can be combined and applied to one D-type paper feed roller 121 as needed.

[0046]

According to one embodiment of the present invention, the length of the feeding area is set to be longer than the minimum necessary feeding distance required for feeding the recording medium. Even if the powder reduces the frictional force in the pickup area and the feed force of the paper feed roller decreases, sufficient paper feed is ensured in the feed area, making it less susceptible to wear and paper dust adhesion. , Non-feed and paper jam can be prevented.

In another embodiment of the present invention, the frictional force with the recording medium in the pickup area is set to be equal to or more than the minimum necessary frictional force within the range of the maximum number of feeds of the sheet feeding device. Within the maximum number of possible feedings,
A good paper feeding state can be maintained without causing non-feed.

[Brief description of the drawings]

FIG. 1 is a schematic side view illustrating an embodiment of a sheet feeding device.

FIG. 2 is a schematic side view illustrating the operation of a paper feed roller.

3A and 3B are schematic diagrams illustrating one embodiment of the paper feed roller of the present invention, wherein FIG. 3A shows a state at the time of product shipment, and FIG. 3B shows a state after the maximum number of sheets that can be fed.

FIG. 4 is a schematic diagram illustrating an embodiment of the paper feed roller of the present invention.

FIG. 5 is a schematic diagram illustrating an embodiment of the paper feed roller of the present invention.

FIG. 6 is a schematic diagram illustrating an embodiment of the paper feed roller of the present invention.

[Explanation of symbols]

120, 120 'Paper feed roller unit 121 D-type paper feed roller 121a Arc part 121b Linear part 121c Corner (feed action start corner) 130 Hopper 133 Hopper spring 135 Hopper cam 150 Separation pad 156 Pad spring 160 Idle roller 200 Pickup area 201 Paper Pickup area 300 Feed area P Recording medium SF Paper feeder L Minimum required feed distance L _D Length of feed area L _P Length of pickup area

Claims (10)

[Claims] 1. A substantially D-shaped side view for feeding a recording medium into a recording apparatus by rotating and contacting the recording medium and feeding the recording medium into the recording apparatus by a frictional force at the time of contact. A sheet feeding device provided with a D-type sheet feeding roller, wherein the D-type sheet feeding roller starts rotating at a corner from a terminal end of a linear portion to a start end of an arc portion as viewed in a rotation direction of the roller. A pickup area which is provided over a predetermined range in the direction and which comes into contact with the recording medium at the time of feeding and starts feeding the recording medium; and a feed area which comes into contact with the recording medium and feeds the recording medium subsequently to the pickup area. those having a region, the length of the fed-feeding region (L _D), than the minimum required feed distance required for feeding the recording medium (L), characterized in that the longer , Paper feeder. 2. The relation according to claim 1, wherein the relation of length of feeding area (L _D ) −minimum required feeding distance (L)> 0 is maintained within the range of the maximum number of possible feedings of the sheet feeding device. A sheet feeding device, characterized in that: 3. A substantially D-shaped side view for feeding a recording medium into the recording apparatus by rotating and contacting the recording medium and feeding the recording medium into the recording apparatus by frictional force at the time of contact. A sheet feeding device provided with a D-type sheet feeding roller, wherein the D-type sheet feeding roller starts rotating at a corner from a terminal end of a linear portion to a start end of an arc portion as viewed in a rotation direction of the roller. A pickup area which is provided over a predetermined range in the direction and which comes into contact with the recording medium at the time of feeding and starts feeding the recording medium; and a feeding area which comes into contact with the recording medium and feeds the recording medium subsequently to the pickup area. And a frictional force with the recording medium in the pickup area,
A paper feeding device characterized in that it is set so as to be equal to or more than a minimum necessary frictional force within a range of a maximum number of possible feedings of the paper feeding device. 4. The paper feeder according to claim 3, wherein at least the pickup area is formed of a material having a large friction coefficient with respect to a recording medium. 5. The sheet feeding device according to claim 3, wherein at least the pickup area is formed of a material having high wear resistance. 6. The sheet feeding device according to claim 3, wherein a pressing force on the recording medium in the pickup area is larger than a pressing force on the recording medium in the feeding area. 7. A recording device comprising the sheet feeding device according to claim 1. Description: 8. The paper feed roller according to claim 7, wherein:
A recording apparatus, wherein a paper detecting unit is provided in a recording medium transport path between the fed recording medium and a paper feed roller that further transports the fed recording medium toward a recording unit. 9. A recording medium, which is incorporated in a paper feeder to supply the recording medium into the recording apparatus, rotates and comes into contact with the recording medium, and feeds the recording medium into the recording apparatus by a frictional force at the time of the contact. A D-shaped paper feed roller having a substantially D-shape in a side view, wherein the D-type paper feed roller starts rotating at a corner from the end of the linear portion to the start of the arc when viewed in the rotation direction of the roller. A pickup area which is provided over a predetermined range in the direction and which comes into contact with the recording medium at the time of feeding and starts feeding the recording medium; and a feed area which comes into contact with the recording medium and feeds the recording medium subsequently to the pickup area. those having a region, the length of the fed-feeding region (L _D), than the minimum required feed distance required for feeding the recording medium (L), characterized in that the longer , D-type feed roller. 10. A recording apparatus, wherein the recording medium is incorporated in a paper feeder to supply the recording medium into the recording apparatus, and rotates to abut on the recording medium.
A substantially D-shaped D-shaped paper feeding roller for feeding a recording medium into the recording apparatus by a frictional force at the time of contact, wherein the D-shaped paper feeding roller is a straight line when viewed in the rotation direction of the roller. A pickup area which is provided over a predetermined range in the rotation direction from a corner from the end of the section to the start of the arc portion, and which comes into contact with the recording medium at the time of feeding and starts feeding of the recording medium; And a feeding area for sending the recording medium in contact with the recording medium subsequent to the pickup area, and a frictional force between the pickup area and the recording medium in the pickup area.
A D-type paper feeding roller, wherein the setting is made so as to be not less than a minimum necessary frictional force within a range of a maximum number of possible feedings of the paper feeding device.