JP2021100890A - Image formation device - Google Patents

Abstract

To provide an image formation device of a pickup-less system possible to suppress occurrence of non-feeding of a strong recording sheet while suppressing occurrence of a fold of a weak recording sheet.SOLUTION: A recording sheet S before entering a separation nip by a contact between a feeding roller and a separation roller is bent by its own contact, and a deflection imparting portion 127b is provided for generating wrinkles on the recording sheet S extending along a conveying direction (arrow direction in the figure), and a tip end portion of the deflection imparting body 127b in contact with the recording sheet S is composed of a flexible member.SELECTED DRAWING: Figure 13

Description

In the present invention, the recording sheet sent out from the inside of the sheet accommodating means by the surface movement of the feeder against which the recording sheet accommodated in the sheet accommodating means is pressed is separated by the separation nip due to the contact between the feeder and the separator. It relates to an image forming apparatus for separating into one image.

Conventionally, as an image forming apparatus of this kind, the one described in Patent Document 1 is known. FIG. 29 is a configuration diagram showing a paper feed cassette in the image forming apparatus described in Patent Document 1. In the figure, the paper feed cassette 970 accommodating a plurality of recording sheets S in a sheet bundle state is taken in and out along the direction orthogonal to the paper surface of the figure with respect to the image forming apparatus main body (not shown). is there. A paper feed roller 981 held in the image forming apparatus main body is arranged in the vicinity of the paper feed cassette 970. The tip of the sheet bundle housed in the paper cassette 970 is pressed upward against the paper feed roller 981 by the movable bottom plate 971 of the paper cassette 970. On the side of the pressure contact region, the paper feed roller 981 and the separation roller 982 are in contact with each other to form a separation nip. When the paper feed roller 981 is rotationally driven, the topmost recording sheet S of the sheet bundle is sent out from the paper cassette 970 toward the separation nip. At this time, a phenomenon called double feeding may occur in which not only the topmost recording sheet S but also the recording sheet S below it is fed from the paper feed tray 970 in a state of overlapping the topmost recording sheet S. .. When a plurality of recording sheets S are overlapped and sandwiched between the separation nips due to double feeding, the highest recording sheet S in direct contact with the paper feed roller 981 is supplied. It is conveyed in the sheet feeding direction following the surface movement of the paper roller 981. On the other hand, the other recording sheets are sent back toward the paper feed cassette 970 following the separation roller 982 that moves on the surface in the separation nip in the direction opposite to that of the paper feed roller 981. By this feed back, even if double feed occurs, only the recording sheet S that is in direct contact with the paper feed roller 981 is separated into one sheet. Then, it is sent to an image drawing device (not shown).

As a means for feeding the recording sheet in the paper cassette toward the separation nip, it is common to use a pickup roller provided separately from the paper feed roller and the separation roller. However, in the image forming apparatus described in Patent Document 1, the paper feed roller 981 plays the role without providing the pickup roller. In such a configuration (hereinafter referred to as a pickupless method), it is possible to reduce the cost by omitting the attachment of the pickup roller.

However, the pickupless method has a problem that when a thin paper or the like with a weak waist is used as the recording sheet, it becomes easy to make a crease on the recording sheet with the separation nip. Specifically, as shown in FIG. 30, in the pickupless method in which the peripheral surface of the paper feed roller 981 is brought into contact with both the tip of the sheet bundle and the separation roller 982, the tip of the sheet bundle and the separation nip The distance to and is very close. Then, when the tip end portion of the recording sheet S sent out from the inside of the paper feed cassette as the paper feed roller 981 is rotationally driven passes through the pressure contact portion between the movable bottom plate 971 and the paper feed roller 981, the paper feed roller 981 It is transported in a slightly floating state without being closely attached to the curved surface. Then, instead of entering straight toward the separation nip, the tip of the separation roller 982 is often abutted in front of the separation nip. In the recording sheet S having a weak waist, when the tip is abutted against the peripheral surface of the separation roller 982, as shown in FIG. 31, a wave that undulates up and down in a direction orthogonal to the transport direction is formed at the tip. When this waviness is sandwiched between the separation nips as it is, the recording sheet S is creases. Even if a guide member is provided to guide the tip of the recording sheet S sent out from the paper cassette toward the separation nip, the recording sheet having a weak waist will have the same crease. This is because the recording sheet with a weak waist abuts its tip against the guide member to form a wavy portion.

Therefore, the present inventors are developing the following new image forming apparatus. That is, in this image forming apparatus, as shown in FIG. 32, a deflection imparting body 985 for imparting deflection to the recording sheet S is provided in front of the separation nip. The deflection imparting body 985 is arranged so as to come into contact with the recording sheet S immediately before entering the separation nip from below in the direction of gravity. When the deflection imparting body 985 contacts a part of the recording sheet S from below in the direction of gravity, the weak recording sheet S is partially bent and conveyed to the recording sheet S as shown in the figure. Wrinkles are generated along (in the direction of the arrow in the figure). By forming such a deflection, it is difficult for the recording sheet S to generate the deflection in the direction orthogonal to the deflection, and the waviness of the recording sheet S shown in FIG. 31 is hindered. As a result, it is possible to suppress the occurrence of creases in the recording sheet S having a weak waist with the separation nip. The paper feed roller 981 and the separation roller 982 shown in FIG. 31 are both short rollers that abut only in the region between the two wrinkles formed on the recording sheet S by the two deflection imparting bodies 985 in FIG. 32. It consists of. Therefore, these two wrinkles are not sandwiched between the separation nips to make a crease.

In the image forming apparatus having such a configuration, when a stiff recording sheet S such as thick paper is used, the present inventors consider that the recording sheet S sent out from the paper feed cassette is stagnant at or around the separation nip. We have found through experiments that it is easy to generate a phenomenon called. The non-delivery occurred for the following reasons. That is, as shown in FIG. 33, one of the two deflection imparting bodies 985 exists at a position shifted to one end side in the roller axis direction with respect to the roller portion of the paper feed roller 981 and the separation roller 982. Further, the other deflection imparting body 985 exists at a position deviated from the roller portion toward the other end side in the roller axis direction. Then, in order to generate wrinkles having a relatively large height as shown in FIG. 32, each tip portion protrudes greatly upward from the transport path of the recording sheet S shown by the arrow in FIG. 31. .. By these two deflection imparting bodies 985, both ends of the recording sheet S in the width direction (direction orthogonal to the transport direction) are greatly lifted in front of the separation nip, thereby raising the central portion of the recording sheet S in the width direction. The paper feed roller 981 is strongly pressed against the region immediately before entering the separation nip on the peripheral surface. As a result, a large transfer resistance is applied to the recording sheet S and the recording sheet S is slipped on the surface of the paper feed roller 981, so that the recording sheet S cannot be fed in the transport direction and non-feed occurs. It will make you.

The present invention has been made in view of the above background, and an object of the present invention is to suppress the occurrence of creases in a recording sheet having a weak waist and to suppress the occurrence of non-feeding of a recording sheet having a strong waist. It is to provide a pickupless type image forming apparatus capable of it.

In order to achieve the above object, the present invention presents the sheet by moving the surface of the sheet accommodating means for accommodating the recording sheet inside itself and the feeder against which the recording sheet accommodated in the sheet accommodating means is pressed. While sandwiching the recording sheet sent out from the accommodating means between the separating nip due to the contact between the feeder and the separating body, the recording sheet overlapping in the separating nip is in direct contact with the feeding body. In an image forming apparatus including a separate feeding means for separating only the recording sheet and an image forming means for forming an image on the recording sheet separated into one by the separated feeding means, the separation nip is provided. A bending-imparting body that bends the recording sheet before entering by its own contact to generate wrinkles extending along the transport direction is provided on the recording sheet, and a tip portion of the bending-imparting body that comes into contact with the recording sheet. Is made of a flexible member.

According to the present invention, in the pickupless image forming apparatus, there is an excellent effect that the occurrence of creases in a recording sheet having a weak waist can be suppressed and the occurrence of non-feeding of a recording sheet having a strong waist can be suppressed.

The schematic block diagram which shows the printer which concerns on embodiment. An enlarged configuration diagram showing an enlarged view of the photoconductor and its surrounding configuration in the printer. A partially enlarged view showing a partially enlarged lower area of the printer. A partially enlarged view of a paper cassette that is being pulled out from the main body of the printer. A perspective view showing a part of the main body housing in a state where a space is created inside by removing the paper cassette. The perspective view which shows the paper feed cassette partially from the rear. A partial perspective view partially showing the front side of the paper cassette. An exploded perspective view showing a separation roller unit of the same paper cassette. A partial perspective view partially showing the front end portion of the paper cassette. A partial perspective view showing a separation roller unit of the same paper cassette mounted in the main body housing and a feeding roller fixed in the main body housing. The vertical sectional view which shows the vertical sectional view of the same feeding roller and the same separation roller unit. A vertical cross-sectional view showing the same vertical cross section in a state where a strong recording sheet is sandwiched between separation nips. The perspective view which shows the guide unit board of the printer together with the recording sheet. An enlarged perspective view showing an enlarged view of the deflection imparting portion of the guide unit plate. An enlarged perspective view showing the same bending imparting portion in a state where the tip portion is bent. An enlarged configuration diagram showing an enlarged view of the separation nip of the printer and its surrounding configuration. An exploded perspective view showing an enlarged view of the same deflection-imparting portion with a code focusing on the function attached to each portion. An exploded perspective view showing an enlarged view of the same bending-imparting portion with a code focusing on the material attached to each portion. The side view which shows the guide unit board. The perspective view which shows the recording sheet which is curled in the paper cassette. The perspective view which shows the paper feed cassette and the feed roller unit case of the printer. A perspective view showing a part of the paper cassette from diagonally above. The explanatory view for demonstrating the state of the recording sheet in the paper feed cassette which is not provided with a curl straightener. The explanatory view for demonstrating the state of the recording sheet in the paper feed cassette provided with the curl straightener. The perspective view which shows the same paper feed cassette to which a curl straightener is attached and detached. The enlarged perspective view of the paper feed cassette for explaining the slide movement of the curl straightener held by the movable bottom plate of the paper feed cassette. The front view which shows the curl straightening body. The perspective view which shows the deformation example of the curl straightening body together with the movable bottom plate of a paper feed cassette. FIG. 6 is a configuration diagram showing a paper feed cassette in the image forming apparatus described in Patent Document 1. The explanatory view for demonstrating the state of the recording sheet which started to be sent out from the same paper cassette. Explanatory drawing to explain the waviness caused by the weak recording sheet around the separation nip. The perspective view for demonstrating the bending and wrinkles given to a recording sheet by a bending body. The perspective view which shows the paper feed roller, the separation roller, and the deflection imparting body in the image forming apparatus under development. The perspective view which shows the main part of the feeding roller of the printer. The side view which shows the main part of the roller prototyped by the present inventors. A side view showing a feeding roller of the printer. An enlarged configuration diagram showing an enlarged view of the weight fixed to the feeding roller. Partial side view showing the rib partition space of the same feeding roller by partially enlarging it. The side view which shows the feeding roller of the printer which concerns on the modification.

Hereinafter, as an image forming apparatus to which the present invention is applied, an electrophotographic printer (hereinafter, simply referred to as a printer) that forms an image by an electrophotographic method will be described. The present invention is not limited to an image forming apparatus that forms an image by an electrophotographic method, but an image that forms an image by another method such as an inkjet method or a toner projection method described in JP-A-2002-307737. It can also be applied to forming devices.

First, the basic configuration of the printer according to the embodiment will be described. FIG. 1 is a schematic configuration diagram showing a printer according to an embodiment. In the figure, the present printer includes a photoconductor 1 as a latent image carrier, a paper feed cassette 100 as a sheet accommodating means configured to be detachable from the main body housing 50, and the like. Inside the paper cassette 100, a plurality of recording sheets S are housed in a sheet bundle state.

The recording sheet S in the paper feed cassette 100 is sent out from the cassette by the rotational drive of the feed roller 35 described later, passes through the separation nip described later, and then reaches the paper feed path 42. After that, it is sandwiched between the transport nips of the first transport roller pair 41 and is transported in the paper feed path 42 from the upstream side to the downstream side in the transport direction. A resist roller pair 49 is arranged near the end of the paper feed path 42. The recording sheet S is temporarily suspended in a state where the tip of the recording sheet S is abutted against the resist nip of the resist roller pair 49. At the time of the abutting, the skew of the recording sheet S is corrected.

The resist roller pair 49 starts rotational driving at a timing when the recording sheet S can be superimposed on the toner image on the surface of the photoconductor 1 by the transfer nip described later, and sends the recording sheet S toward the transfer nip. At this time, the first transport roller pair 41 starts rotational driving at the same time, and the temporarily suspended transport of the recording sheet S is restarted.

The main body housing of this printer holds a manual paper feed unit including a manual feed tray 43, a manual feed feed roller 44, a separation pad 45, and the like. The recording sheet manually fed to the manual feed tray 43 of the manual paper feed unit is fed out of the manual feed tray 43 by the rotational drive of the manual feed feed roller 44. Then, after passing through the separation nip due to the contact between the manual feed roller 44 and the separation pad 45, the paper enters the region on the upstream side of the resist roller pair 49 in the paper feed path 42. Then, in the same manner as the recording sheet S sent out from the paper cassette 100, it is sent to the transfer nip described later after passing through the resist roller pair 49.

FIG. 2 is an enlarged configuration diagram showing an enlarged view of the photoconductor 1 and its surrounding configuration in the present printer. Around the drum-shaped photoconductor 1 that is rotationally driven in the counterclockwise direction in the figure, a recovery screw 3, a cleaning blade 2, a charging roller 4, a latent image writing device 7, a developing device 8, a transfer roller 10, and the like are arranged. It is arranged. The charging roller 4 provided with the conductive rubber roller portion rotates while in contact with the photoconductor 1 to form a charging nip. A charging bias output from a power source (not shown) is applied to the charging roller 4. As a result, in the charging nip, an electric discharge is generated between the surface of the photoconductor 1 and the surface of the charging roller 4, so that the surface of the photoconductor 1 is uniformly charged.

The latent image writing device 7 includes an LED array, and performs optical scanning with LED light on the uniformly charged surface of the photoconductor 1. Of the uniformly charged background portion of the photoconductor 1, the region irradiated with light by this light scanning attenuates the potential. As a result, an electrostatic latent image is formed on the surface of the photoconductor 1.

The electrostatic latent image passes through the developing region facing the developing device 8 as the photoconductor 1 is rotationally driven. The developing apparatus 8 has a circulating transport section and a developing section, and the circulating transport section contains a developer containing toner and a magnetic carrier. The circulation transport unit includes a first screw 8b for transporting the developer for supplying to the developing roller 8a, which will be described later, and a second screw 8c for transporting the developer in an independent space located directly below the first screw 8b. doing. Further, it also has an inclined screw 8d for transferring the developer from the second screw 8c to the first screw 8b. The developing rollers 8a, the first screw 8b, and the second screw 8c are arranged in a posture parallel to each other. On the other hand, the inclined screw 8d is arranged in an inclined posture from them.

The first screw 8b conveys the developer from the back side to the front side in the direction orthogonal to the paper surface in the figure as it is driven to rotate. At this time, a part of the developing agent is supplied to the developing rollers 8a arranged to face each other. The developer conveyed by the first screw 8b to the vicinity of the front end in the direction orthogonal to the paper surface in the figure is dropped onto the second screw 8c.

The second screw 8c receives the used developer from the developing roller 8a, and conveys the received developer from the back side to the front side in the direction orthogonal to the paper surface in the figure along with its own rotational drive. .. The developer conveyed by the second screw 8c to the vicinity of the front end in the direction orthogonal to the paper surface in the figure is delivered to the inclined screw 8d. Then, as the inclined screw 8d is rotationally driven, it is conveyed from the front side to the back side in the direction orthogonal to the paper surface in the figure, and then becomes the first screw 8b near the end portion on the back side in the same direction. Delivered.

The developing roller 8a includes a rotatable developing sleeve made of a tubular non-magnetic member, and a magnet roller fixed in the sleeve so as not to be carried around the developing sleeve. Then, a part of the developing agent conveyed by the first screw 8b is pumped up on the surface of the developing sleeve by the magnetic force generated by the magnet roller. The layer thickness of the developer carried on the surface of the developing sleeve is regulated as it passes around the surface of the developing sleeve and passes through the opposite positions of the sleeve and the doctor grade. After that, it moves while rubbing against the surface of the photoconductor 1 in the developing region facing the photoconductor 1.

A development bias having the same polarity as the background potential of the toner or the photoconductor 1 is applied to the development sleeve. The absolute value of this development bias is larger than the absolute value of the latent image potential and smaller than the absolute value of the background potential. Therefore, in the developing region, a developing potential that electrostatically moves the toner from the sleeve side to the latent image side acts between the electrostatic latent image of the photoconductor 1 and the developing sleeve. On the other hand, between the background portion of the photoconductor 1 and the developing sleeve, a background potential that electrostatically moves the toner from the background portion side to the sleeve side acts. As a result, in the developing region, toner is selectively adhered to the electrostatic latent image of the photoconductor 1, and the electrostatic latent image is developed.

The developer that has passed through the developing region enters the facing region between the sleeve and the second screw 8c as the developing sleeve rotates. In this facing region, a repulsive magnetic field is formed by two magnetic poles having different polarities from each other among the plurality of magnetic poles provided in the magnet roller. The developer that has entered the opposite region is separated from the surface of the developing sleeve by the action of the repulsive magnetic field and collected on the second screw 8c.

The developer conveyed by the inclined screw 8d contains the developer recovered from the developing roller 8a, and the developer contributes to the development in the developing region, so that the toner concentration is lowered. The developing apparatus 8 includes a toner concentration sensor (not shown) that detects the toner concentration of the developer conveyed by the inclined screw 8b. The control unit 51 outputs a replenishment operation signal for replenishing the toner to the developer conveyed by the inclined screw 8b, if necessary, based on the detection result by the toner concentration sensor.

A toner cartridge 9 is arranged above the developing device 8. In the toner cartridge 9, the toner contained therein is agitated by an agitator 9b fixed to the rotary shaft member 9a. Then, the toner replenishing member 9c is rotationally driven in response to the replenishment operation signal output from the control unit 51, so that an amount of toner corresponding to the rotational drive amount is replenished to the inclined screw 8b of the developing device 8.

The toner image formed on the photoconductor 1 by the development enters the transfer nip where the photoconductor 1 and the transfer roller 10 serving as the transfer means come into contact with each other as the photoconductor 1 rotates. A charging bias having a polarity opposite to the latent image potential of the photoconductor 1 is applied to the transfer roller 10, whereby a transfer electric field is formed in the transfer nip.

As described above, the resist roller pair 49 feeds the recording sheet S toward the transfer nip at a timing at which the recording sheet S can be superimposed on the toner image on the photoconductor 1 in the transfer nip. The toner image on the photoconductor 1 is transferred to the recording sheet S which is brought into close contact with the toner image by the transfer nip by the action of the transfer electric field and the nip pressure.

The transfer residual toner that has not been transferred to the recording sheet S adheres to the surface of the photoconductor 1 after passing through the transfer nip. The transfer residual toner is scraped off from the surface of the photoconductor 1 by the cleaning blade 2 in contact with the photoconductor 1, and then sent to the outside of the unit casing by the recovery screw 3. The transfer residual toner discharged from the unit casing is sent to a waste toner bottle (not shown) by a transfer device (not shown).

The surface of the photoconductor 1 cleaned by the cleaning blade 2 is statically discharged by a static elimination means (not shown), and then uniformly charged again by the charging roller 4. Foreign substances such as toner additives and toner that cannot be completely removed by the cleaning blade 2 adhere to the charging roller 4 that is in contact with the surface of the photoconductor 1. This foreign matter is transferred to the cleaning roller 5 in contact with the charging roller 4, and then scraped off from the surface of the cleaning roller 5 by the scraper 6 in contact with the cleaning roller 5. The scraped foreign matter falls on the recovery screw 3 described above.

In FIG. 1, the recording sheet S that has passed through the transfer nip where the photoconductor 1 and the transfer roller 10 come into contact with each other is sent to the fixing device 44. The fixing device 44 forms a fixing nip by abutting the fixing roller 44a including a heat generating source such as a halogen lamp and the pressure roller 44b pressed toward the fixing roller 44a. A toner image is fixed on the surface of the recording sheet S sandwiched between the fixing nips by the action of heating or pressurizing. After that, the recording sheet S that has passed through the fixing device 44 passes through the paper ejection path 45 and is sandwiched between the paper ejection nips of the paper ejection rollers vs. 46.

This printer can switch between a single-sided mode in which an image is formed on only one side of the recording sheet S and a double-sided mode in which an image is formed on a good edge of the recording sheet S. In the case of the single-sided mode or the double-sided mode in which images are already formed on both sides of the recording sheet S, the paper ejection rollers vs. 46 continue to drive in the forward direction, so that the recording sheet in the paper ejection path 45 Discharge S to the outside of the machine. The discharged recording sheet S is stacked in a stack portion provided on the upper surface of the main body housing 50.

On the other hand, in the double-sided mode and when the image is formed on only one side of the recording sheet S, the image is ejected at the timing when the end of the recording sheet S enters the paper ejection nip of the paper ejection roller vs. 46. The paper roller pair 46 is driven in reverse. At this time, the switching claw 47 arranged near the end of the paper ejection path 45 operates to close the paper ejection path 45 and open the inlet of the reverse retransmission path 48. The recording sheet S, which has started to reverse by the reverse drive of the paper ejection roller vs. 46, is sent into the reverse retransmission path 48. Then, after being conveyed while being turned upside down in the reverse retransmission path 48, it is retransmitted to the resist nip of the resist roller vs. 49. After that, the toner image is transferred to the other surface by the transfer nip, and then discharged to the outside of the machine via the fixing device 44, the paper ejection path 45, and the paper ejection roller pair 46.

FIG. 3 is a partially enlarged view showing a partially enlarged lower region of the printer. The paper cassette 100 has a sheet bundle composed of a plurality of recording sheets S placed on the movable bottom plate 101. The movable bottom plate 101 is urged toward the feed roller 35 by the bottom plate spring 103. A bottom plate pad 102 made of an elastic member is fixed to the tip of the movable bottom plate 101. The tip of the sheet bundle is pressed toward the feeding roller 35 by the force of the bottom plate spring 103 while being sandwiched between the bottom plate pad 102 and the feeding roller 35.

When the feeding roller 35 rotates, the highest recording sheet S at the top of the sheet bundle is sent out from the movable bottom plate 101. Then, it enters the separation nip due to the contact between the feed roller 35 and the separation roller 121. In this way, in a state where the recording sheet S is pressed against the feeding roller 35 by the pressing means including the movable bottom plate 101, the bottom plate pad 102, the bottom plate spring 103, etc., the feeding roller 35 is driven from the inside of the cassette. The recording sheet S is sent out. In such a configuration, it is possible to reduce the cost by omitting the attachment of the pickup roller to the paper feed cassette 100. In other words, this printer uses a pickupless method to reduce costs.

Generally, a rotational driving force for moving the surface of the separation roller 121 in the direction opposite to that of the feeding roller 35 is applied to the separation roller 121, but in this printer, the rotational driving force is applied. Is not given. The separation roller 121 rotates only by following the feeding roller 35 and the recording sheet S in the separation nip.

One end side of the rotation shaft of the separation roller 121 is rotatably supported by a torque limiter (not shown). When the recording sheet S does not enter the separation nip, the separation roller 121 comes into direct contact with the feeding roller 35. When the feeding roller 35 is rotationally driven in this state, a relatively strong driving force is applied from the feeding roller 35 to the separation roller 121. As a result, the torque of the driven rotation of the separation roller 121 exceeds a predetermined threshold value, so that the torque limiter allows the driven rotation of the separation roller 121. That is, when the recording sheet S does not enter the separation nip, the separation roller 121 rotates along with the feeding roller 35 in a driven manner.

Further, when only one recording sheet S enters the separation nip, only one recording sheet S is interposed between the separation roller 121 and the feeding roller. When the feeding roller 35 is rotationally driven in this state, a strong conveying force is applied from the feeding roller 35 to the recording sheet S, and the recording sheet S moves in the sheet feeding direction. At the same time, a relatively strong driving force is applied from the feed roller 35 to the separation roller 121 via the recording sheet S. As a result, the torque of the driven rotation of the separation roller 121 exceeds a predetermined threshold value, so that the torque limiter allows the driven rotation of the separation roller 121. That is, even when only one recording sheet S has entered the separation nip, the separation roller 121 is driven to rotate.

On the other hand, it is assumed that a plurality of recording sheets S have entered the separation nip in a state of being overlapped by double feeding. In this case, since a relatively strong conveying force is applied by the feeding roller 35 to the uppermost recording sheet S that comes into direct contact with the feeding roller 35 at the separation nip, the uppermost recording sheet S is a sheet. It is conveyed in the feed direction. Further, the remaining recording sheets other than the uppermost recording sheet S are subjected to transfer resistance by being pressurized by the separation nip. When this transport resistance exceeds the frictional resistance between the uppermost recording sheet S and the second recording sheet S, slip occurs between the sheets. Then, due to this slip, the torque of the driven rotation of the separation roller 121 becomes equal to or less than a predetermined threshold value, so that the torque limiter does not allow the driven rotation of the separation roller 121. Then, the transport resistance with respect to the second and subsequent recording sheets S further increases, and the movement of the second and subsequent recording sheets S stops. In this way, the separation roller 121 separates the other recording sheets from the highest recording sheet S while imparting a transfer resistance to the plurality of recording sheets S.

In such a configuration, the recording sheet S is separated by the separation nip without applying the rotational driving force by the motor to the separation roller 121, so that the drive transmission means for transmitting the drive to the separation roller 121 is omitted and the cost is low. It is possible to reduce the cost.

FIG. 4 is a partially enlarged view partially showing the paper feed cassette 100 being pulled out from the main body housing. As shown in the figure, in this printer, the separation roller 121 is held by the paper feed cassette 100 and is attached to and detached from the main body housing 50 together with the paper feed cassette 100. As a result, the paper feed cassette 100 can be attached to and detached from the main body housing 50 by sliding it in the left-right direction in the figure instead of the rotation axis direction of the rollers. This is because the separation roller 121 moves together with the paper feed cassette 100, so that the separation roller 121 does not get in the way when the paper feed cassette 100 is slid and moved in the direction of the arrow A along the left-right direction in the figure.

When a jam occurs with the recording sheet S sandwiched between the separation nips, the operator slides the paper cassette 100 in the direction of arrow A in the drawing and pulls it out from the main body housing 50. Then, the separation roller 121 is taken out together with the paper feed cassette 100 and the separation nip disappears, but the jam sheet remains in the main body housing 50 because it is sandwiched between the transfer nips of the first transfer roller vs. 41.

The space generated in the main body housing 50 by pulling out the paper feed cassette 100 from the main body housing 50 is largely opened in the direction of arrow A in the drawing, which is the cassette pulling out direction. Through this opening, the operator can easily see the jam sheet from its surface direction. Then, the jam sheet can be pulled out from the transfer nip by the first transfer roller pair 41 while grasping both ends of the jam sheet in the roller rotation axis direction with both hands inserted into the opening. At this time, by applying tensile force to both ends of the jam sheet, the concentration of the tensile force is suppressed as compared with the case where only one end of the jam sheet is gripped, and the jam sheet is torn. It becomes difficult.

Therefore, in this printer, it is possible to suppress the tearing of the jam sheet during the jam processing. The drawing direction (arrow A direction in the drawing) of the paper feed cassette from the main body housing 50 in this printer is a direction in which the paper feed cassette 100 is moved from the sheet accommodating portion 105 side to the separation roller unit 120 side as shown in the drawing. Is.

FIG. 5 is a perspective view partially showing the main body housing 50 in a state where a space is created inside by removing the paper feed cassette (100). The direction of arrow B in the figure is the direction of the rotation axis of the feeding roller (35) (not shown). In the figure, only one end side in the same rotation axis direction in the main body housing is shown.

A rail 53 extending in the attachment / detachment direction of the paper feed cassette (not shown) is provided on one end side of the bottom portion of the main body housing 50 in the same rotation axis direction. Further, although not shown in the figure, a similar rail is provided on the other end side in the same rotation axis direction. The paper cassettes are attached to and detached from the main body housing 50 by being slid along the extending direction of the rails while being placed on the rails. Further, by placing it on the rail, positioning in the height direction is performed in the main body housing 50.

In the main body housing 50 shown in the figure, the member extending in the height direction is the right side plate of the main body housing 50. Although not shown in the figure, a left plate extending in the height direction is also provided on the other end side in the same rotation axis direction. On the inner wall of the right side plate of the main body housing 50, a positioning stopper 51 for positioning the paper feed cassette in the attachment / detachment direction in the main body housing 50 is provided. Further, a similar positioning stopper is provided on the inner wall of the left side plate of the main body housing 50 (not shown). When the paper cassette is mounted on the rail described above in the main body housing 50 and pushed into the inside, the paper cassette is attached and detached by abutting the abutting portion provided on the main body 50 against the positioning stopper (for example, 51) described above. Directional positioning is done.

If the abutting portion of the paper cassette is simply abutted against the positioning stopper, the paper cassette may be pushed out in the take-out direction when some impact is applied to the main body housing 50. Therefore, a locking member 52 is provided on the inner wall of the right side plate of the main body housing 50 so as to be movable in the same rotation axis direction (arrow B direction). The locking member 52 is urged by a spring (not shown) and is restrained at a position protruding into the housing from the inner surface of the right side plate of the main body 50 as shown in the drawing. The locking member 52 is provided with a taper as shown in the figure. Although not shown in the figure, a similar locking member 52 is also provided on the inner wall of the left side plate of the main body housing 50.

FIG. 6 is a perspective view partially showing the paper cassette 100 from the rear. A retaining protrusion 106 is provided so as to project from the outer surface of the right side plate of the paper cassette 100. Positioning of the paper cassette 100 in the height direction by placing the positioning portion 107 provided on the outer surface of the bottom wall of the paper cassette 100 on the rail 53 provided at the bottom of the main body housing 50 shown in FIG. Is done. As the paper feed cassette 100 is pushed toward the inside of the main body housing 50 on the rail 53, the retaining protrusion 106 of the paper feed cassette 100 rubs against the taper of the locking member 52 of the main body housing 50. Along with this rubbing, the locking member 52 is pushed toward the outside of the side plate, and the amount of protrusion from the inner surface of the side plate is reduced. Immediately before the paper cassette 100 moves to the position where the positioning abutting portion 105 abuts against the positioning stopper 51 of the main body housing 50 and is positioned, the retaining protrusion 106 of the paper feed cassette 100 moves to the position where the main body housing 50 abuts. Separate from the locking member 52. Then, the locking member 52, which has reduced the amount of protrusion from the inner surface of the side plate, protrudes at once to the position shown in FIG. 5 by the urging force of the spring. Then, by bringing the protruding portion into contact with the back surface of the retaining protrusion 106 of the paper cassette 100, the paper cassette 100 is prevented from moving in the pull-out direction, and the paper cassette 100 is restrained at a regular position. As a result, even if a sudden impact is applied to the main body housing 50, the paper feed cassette 100 can continue to be constrained to a regular position in the attachment / detachment direction.

The locking member 52 is also provided with a steep taper on the surface that is not visible on the back side in the figure. The locking member 52 cannot be pushed down by the retaining protrusion 106 of the paper feed cassette 100 with a force of about impact. However, when the operator pulls out the paper cassette 100 with a certain amount of force, the retaining protrusion 106 of the paper cassette 100 pushes down the locking member 52 while strongly rubbing against the taper on the back side of the locking member 52. I will go. As a result, the operator can pull out the paper feed cassette 100 from the inside of the main body housing 50.

By positioning the paper cassette 100 in the height direction and the attachment / detachment direction as described above, the separation roller (121) held in the paper cassette 100 is accurately positioned in the main body housing 50. To.

In addition, in order to position the paper cassette 100 more accurately in the height direction, the following configuration may be adopted. That is, the rail portion and the minute protrusions slightly protruding from the surface of the rail portion are formed on the positioning stoppers (for example, 51) provided on the two side plates of the main body housing 50, respectively, and the minute protrusions provided on the paper feed cassette 100 are provided. The positioning part is made to ride on the minute protrusion. At the same time, the abutting portion (for example, 105) of the paper feed cassette 100 is abutted against the abutting portion of the positioning stopper.

FIG. 7 is a partial perspective view partially showing the front side of the paper cassette 100. In the figure, for convenience, the front cover (cover with a handle for pulling out) of the paper cassette 100 is not shown. As shown in the drawing, the separation roller 121 is configured as a separation roller unit 120 together with some other parts, and is integrally attached to and detached from the mounted portion of the paper feed cassette 100. In this way, by unitizing the separation roller 121, parts can be shared with other models and the cost can be reduced. Specifically, cassettes of other models having different specifications from this printer also adopt the same configuration as the paper feed cassette 100 of this printer. However, since the number of recording sheets S accommodated is different from that of the paper feed cassette 100 of this printer, the thickness of the cassette is different. Although the paper cassettes have different specifications, the separation roller unit 120 has exactly the same specifications. In this way, the parts are standardized.

FIG. 8 is an exploded perspective view showing the separation roller unit 120. A torque limiter 122 is connected to the rotating shaft member 121a of the separation roller 121. The role of the torque limiter 122 is as described above. The torque limiter 122 and the separation roller 121 are held by the swing holder 123. The side of the torque limiter 122 opposite to the connecting portion with the rotating shaft member 121a is fixed to the right side plate of the swing holder 123. Further, the end side of the rotary shaft member a of the separation roller 121 opposite to the connecting portion is rotatably supported by the left side plate of the swing holder 123.

The swing holder 123 that holds the torque limiter 122 and the separation roller 121 in this way is housed in a housing member including an upper cover 126 and a base cover 124. Specifically, the swing shaft portions 123a arranged on the coaxial line are projected from the right side plate and the left side plate of the swing holder 123, respectively. The swing holder 123 housed in the base cover 124 engages the swing shaft portions with the shaft holes 124a and the notch 124b of the base cover 124. As a result, the swing holder 123 is supported by the base cover 124 so as to swing around the swing shaft portion 123a.

The upper cover 126 fits into the base cover 124 from above. In this state, the peripheral surface of the separation roller 121 inside the cover is exposed to the outside through the opening 126a provided in the upper cover 126 (see FIG. 7). A coil spring 125 as an urging means is fixed to the base cover 124. The coil spring 125 urges the swing holder 123 in the direction from the base cover 124 side to the upper cover 126 side with the swing shaft portion 123a as the center. When the separation roller unit 120 is not attached to the paper feed cassette 100 as shown in FIG. 7, the peripheral surface of the separation roller 121 abuts on the back surface of the upper cover 126.

In this printer, the rightmost surface of the main body housing 50 shown in FIG. 1 is the front surface. In addition, the leftmost surface in the figure is the back surface. Further, the back end surface of the main body housing 50 in the direction orthogonal to the paper surface in the figure is the right side surface. Further, the front end surface in the same direction is the left side surface. That is, in this printer, the paper cassette 100 mounted in the main body housing 50 is pulled out toward the front of the printer. Further, the paper cassette 100 is pushed toward the rear of the printer and mounted in the main body housing 50. Hereinafter, the direction from the rear side to the front side of the printer along the attachment / detachment direction is simply referred to as the front side. Also, the opposite direction is simply called backward.

As shown in FIG. 9, when the separation roller unit 120 is mounted on the mounted portion of the paper cassette 100, the bottom plate pad 102 fixed to the tip of the movable bottom plate 101 of the paper cassette 100 is in the vicinity of the separation roller 121. Located in. As described above, the bottom plate pad 102 presses the recording sheet housed in the paper feed cassette 100 toward the feeding roller (35).

FIG. 10 is a partial perspective view showing a separation roller unit 120 of the paper feed cassette 100 mounted in the main body housing and a feeding roller 35 fixed in the main body housing. In the process of mounting the paper feed cassette 100 on the main body housing while sliding it on the rail of the main body housing, the feed roller 35 fixed in the main body housing and the separation roller held by the paper feed cassette 100 It comes into contact with 121. Specifically, the separation roller 121 before coming into contact with the feeding roller 35 makes a part of its peripheral surface more than the upper cover 126 through the opening of the upper cover 126 of the separation roller unit 120 (126a in FIG. 8). It is projected to the outside. The separation roller 121, which is pushed into the main body housing together with the paper feed cassette 100 in this state, eventually abuts on the peripheral surface of the feeding roller 35 fixed in the main body housing. When the paper cassette 100 is further pushed into the main body housing, the separation roller 121 is pushed back to the feed roller 35. Due to this pushing back force, the swing holder 123 begins to revolve from the upper cover 126 side toward the base cover 124 side around the swing shaft portion 123a against the urging force of the coil spring 125. As a result, the separation roller 121 gradually revolves from the feed roller 35 side toward the separation roller 121 side around the swing shaft portion 123a, and the contact portions of both rollers are also separated from the feed roller 35 side. It gradually moves toward the roller 121 side. When the paper cassette 100 is pushed to the proper mounting position, the separation roller 121 is completely separated from the back surface of the upper cover 126.

When a strong material such as thick paper is used as the recording sheet S, the recording sheet S sandwiched between the separation nips pushes the separation roller 121 back in the direction away from the feeding roller 35 due to the restoring force due to the strength of the waist. There is a risk. Then, the recording sheet S is not fed due to this force. Specifically, the swing holder 123 urged toward the feed roller 35 by the coil spring 125 (see FIG. 8) is separated from the feed roller 35 around the swing shaft portion 123a by the above-mentioned force. Revolving in the direction, the separation roller 121 is largely separated from the feed roller 35. As a result, the conveying force due to the surface movement of the feeding roller 35 is not transmitted to the recording sheet S, and the recording sheet S is not fed. Hereinafter, this non-feeding is referred to as "non-feeding due to pushback".

FIG. 11 is a vertical cross-sectional view showing the feeding roller 35 and the separating roller unit 120. Two convex portions 126b and 126c arranged in the roller axis direction are provided around the opening (126a) in the upper cover 126 of the separation roller unit 120. In the figure, the alternate long and short dash line labeled Ln is an extension of the separation nip. The alternate long and short dash line labeled Ls is an extension of the surface of the convex portion 126b and the convex portion 126c. The convex portions 126b are separated in the main body housing while being arranged at a position on one end side along the rotation axis direction with respect to one end surface (right end surface in the drawing) of the columnar roller portion 121b of the separation roller 121 in the rotation axis direction. It protrudes toward the feeding roller 35 from the nip. Further, the convex portions 126c are arranged at the other end side along the rotation axis direction with respect to the other end surface (left end surface in the drawing) of the roller portion 121b in the rotation axis direction, and are supplied from the separation nip in the main body housing. It projects toward the feed roller 35 side.

As shown in FIG. 12, when the stiff recording sheet S is sandwiched between the separation nips, the portion of the entire area of the recording sheet S in the roller axial direction that is in contact with the first contact portion 126b and the second contact. The region between the part in contact with the portion 126c is slightly bent. Specifically, it bends toward the separation nip located on the separation roller 121 side of the surface of those contact portions. Since the recording sheet S shown in the figure is a strong sheet, if it bends in that way, it tries to eliminate the bending by the restoring force. Therefore, the recording sheet S moves away from the feeding roller 35 with respect to the separation roller 121. Will not be given the power of. As a result, it is possible to avoid the occurrence of "non-feed due to pushback" caused by the strong recording sheet S applying the above-mentioned force to the separation roller 121 at the separation nip.

In FIG. 11, the peripheral surface of the separation roller 121 protrudes to the outside through the opening provided in the upper cover 126, and slightly protrudes toward the feeding roller 35 side from the surface of the upper cover 126 (hereinafter, protrudes). The peripheral surface is called the protruding peripheral surface). If the stiff recording sheet S conveyed toward the separation nip abuts on the protruding peripheral surface of the separation roller 121 on the front side of the separation nip, the following may occur. That is, the swing holder 123 revolves around the swing shaft portion 123a in a direction away from the feed roller 35, whereby the separation roller 121 is largely separated from the feed roller 35 and the recording sheet S is not fed. There is a risk of causing it. Hereinafter, this non-feeding is referred to as "non-feeding due to the end". In particular, in a configuration such as this printer in which the driving force of the motor is not transmitted to the separation roller 121, even if the recording sheet S hits the protruding peripheral surface of the separation roller 121 and stops the driven rotation of the roller, the separation roller 121 No reverse drive is applied. For this reason, it is not possible to apply a force to push back the recording sheet S that has hit the protruding peripheral surface of the separation roller 121 toward the cassette, so that "non-feed due to hitting" is likely to occur.

Therefore, in this printer, as shown in FIG. 10, the guide unit plate 127 is fixed to the upper cover 126. The guide unit plate 127 includes a separation nip guide portion 127a and two deflection imparting portions 127b. The separation nip guide portion 127a is arranged in front of the roller portion 121b of the separation roller 121 and comes into contact with the recording sheet S before entering the separation nip. Then, the recording sheet S is guided toward the separation nip while preventing the recording sheet S from hitting the protruding peripheral surface of the separation roller 121 before entering the separation nip. By preventing the recording sheet S from abutting against the protruding peripheral surface of the separation roller, it is possible to avoid the occurrence of “non-feeding due to abutting” of the recording sheet S. The roles of the two deflection imparting portions 127b in the guide unit plate 127 will be described later.

Next, a characteristic configuration of the printer according to the embodiment will be described.
As described above, in a pickupless image forming apparatus such as this printer, when a recording sheet S having a weak waist is used, the sheet waviness as shown in FIG. 31 on the front side of the separation nip. Is likely to occur and creases are easily made on the sheet.

Therefore, in this printer, as shown in FIG. 10, two deflection imparting portions 127b are provided on the guide unit plate 127. The deflection imparting portion 127b comes into contact with the recording sheet S immediately before entering the separation nip from below in the direction of gravity. As a result, as shown in FIG. 13, the recording sheet S having a weak waist is bent to generate wrinkles on the recording sheet S along the transport direction (in the direction of the arrow in the figure). The formation of this deflection prevents the recording sheet S from generating a deflection (FIG. 31) in a direction orthogonal to the deflection. As a result, the occurrence of creases in the recording sheet S can be suppressed.

In FIG. 10, the separation nip guide portion 127a is formed by bending a part of the sheet metal constituting the main body of the guide unit plate 127. Further, the root portions of the two bending imparting portions 127b are also formed by bending a part of the sheet metal constituting the main body of the guide unit plate 127. However, in the bending imparting member 127b, the tip portion in contact with the back surface of the recording sheet S is not a bent sheet metal of the main body, but is formed separately from the sheet metal.

In the model under development, the present inventors used a model in which the entire region from the root to the tip thereof was formed by bending the sheet metal, unlike the deflection imparting portion 127b shown in the figure. And, in this model under development, in addition to the "non-feeding due to pushback" and "non-feeding due to the end" explained so far, it was easy to cause "non-feeding due to slip". This "non-feed due to slip" occurs as follows. That is, the bending imparting portion strongly presses the recording sheet S toward the feeding roller, thereby imparting a large transfer resistance to the recording sheet S and causing the recording sheet S to slip on the surface of the feeding roller. Due to this slip, the recording sheet S cannot be fed in the transport direction, causing "non-feed due to slip".

Therefore, in this printer, as shown in FIG. 14, the tip portion 127d in contact with the recording sheet is formed of a material different from the main body portion 127c made of sheet metal in the entire area of the bending imparting portion 127b. .. Specifically, a resin sheet, which is a flexible member, is used as such a material. This resin sheet can be freely bent by applying a certain amount of force. However, when a weak material such as thin paper is used as the recording sheet S, when it comes into contact with the recording sheet S, its own waist strength is superior to that of the recording sheet S. Therefore, maintain a straight posture without bending. As a result, the recording sheet S having a weak waist is bent as shown in FIG. 13 to suppress its waviness, so that the occurrence of creases can be suppressed. On the other hand, when a strong material such as thick paper is used as the recording sheet S, as shown in FIG. 15, the recording sheet S itself moves toward the downstream side in the sheet transport direction as the recording sheet S comes into contact with the recording sheet S. It bends flexibly. By bending in this way, the force that presses the recording sheet in the separation nip toward the feeding roller 35 is reduced to reduce the transport resistance, so that the stiff recording sheet S slips on the surface of the feeding roller 35. Suppress the occurrence of. As a result, it is possible to suppress the occurrence of "non-feeding due to slip" of the recording sheet S having a strong waist.

FIG. 16 is an enlarged configuration diagram showing the separated nip and its surrounding configuration in an enlarged manner. In the figure, the arrow indicates the transport path of the recording sheet S from the bottom plate pad 102 of the movable bottom plate 101 to the separation nip. Since the recording sheet (not shown) has a small sheet-like thickness, it moves substantially at the position of the arrow and enters the separation nip. In the bending imparting portion 127b of the guide unit plate 127, the main body portion 127c made of sheet metal exists on the lower side (separation roller 121 side) than the transport path indicated by the arrow, so that the recording sheet S is on the main body portion 127c. Contact is rare. On the other hand, it can be seen that the tip portion 127a made of the resin sheet projects significantly upward in the direction of gravity from the transport path (largely projects toward the feeding roller 35 side). In this way, the tip portion 127d protrudes significantly upward in the direction of gravity from the transport path indicated by the arrow, so that the recording sheet S can be reliably contacted and wrinkles formed of bending can be generated in the recording sheet S. On the other hand, since the main body portion 127c made of metal is located below the transport path in the direction of gravity, it is possible to prevent the recording sheet S from being pushed toward the feeding roller 121 by the highly rigid main body portion 127c. be able to. The deflection imparting portion 127b shown in the figure is located closer to the front side in the drawing than the roller portion of the feeding roller 35 and the roller portion of the separation roller 121 in the roller axis direction. Therefore, in the roller axis direction, the recording sheet is lifted above the transport path by the flexure imparting portion 127b at the position of the deflection imparting portion 127b, but the recording sheet moves at the position of the transport path at the position of the separation nip.

FIG. 17 is an exploded perspective view showing a deflection imparting portion 127b in the guide unit plate 127. The bending imparting portion 127b is formed by a sheet metal which is a main body forming member forming the main body portion 127c and a resin sheet which is a tip portion forming member forming the tip portion 127d. By using a resin sheet or the like different from the sheet metal of the main body 127c as the material of the tip 127d, the desired flexibility can be easily exhibited with respect to the tip 127d as designed.

As shown in FIG. 18, the sheet metal for forming the main body portion 127c of the bending imparting portion 127b and the resin sheet for forming the tip portion 127c have a rising portion α, a refracting portion β, and a tip, respectively. An extending portion γ is provided. The rising portion α is a portion that rises from the lower side to the upper side in the direction of gravity. Further, the refracting portion β is a portion that refracts from the paper feed cassette side to the separation nip side in the sheet transport direction at the position of the upper end of the rising portion α. Further, the tip extending portion γ is a portion extending from the refracting portion β toward the tip side in contact with the recording sheet S.

FIG. 19 is a side view showing the guide unit plate 127. In the figure, the direction from the left side in the figure toward Migawa is the sheet transport direction. The region on the right side of the guide unit plate 127 in the drawing is the region on the separation roller side with the guide unit plate 127 in the sheet transport direction as a boundary. The area on the left side of the guide unit plate 127 in the drawing is the area on the paper feed cassette side with the guide unit plate 127 in the sheet transport direction as a boundary. On the surface on the separation nip side of the rising portion α of the sheet metal serving as the main body forming member, the surface on the paper feed cassette side at the rising portion α of the resin sheet serving as the tip forming member is fixed by the double-sided tape 127e. Further, the surface of the resin sheet on the rising portion α on the separation roller side is fixed to the upper cover (126 in FIG. 8) of the separation roller unit by double-sided tape 127f. By fixing them, the tip portion (127d) made of the resin sheet of the bending imparting portion (127b) is firmly fixed to the main body portion (127c) made of sheet metal.

However, the tip extending portion γ of the resin sheet is not fixed to the sheet metal or other members. The tip extending portion γ of the resin sheet is supported by the refracting portion β of the resin sheet in a state of being located below the tip extending portion γ of the sheet metal in the direction of gravity. As a result, the tip extending portion γ of the resin sheet that functions as the tip portion 127d of the bending imparting portion 127b can freely swing (bend) around the refracting portion β of the resin sheet. Then, the tip portion 127b can be flexed more favorably than in the case where the tip extending portion γ of the resin sheet is attached to the lower surface of the tip extending portion γ of the sheet metal. Further, when the tip extending portion γ of the resin sheet is attached to the lower surface of the tip extending portion γ of the sheet metal, the tip extending portion γ and the rising portion α of the resin sheet are bound to the bending portion β of the resin sheet. Will be attached to each sheet metal, but in this case, the work efficiency will be significantly deteriorated. By setting the place where the resin sheet is attached to one place of the rising portion α, deterioration of work efficiency can be avoided.

In FIG. 18, the corners of the extending portion γ of the tip of the resin sheet forming the tip portion 127c of the bending imparting portion (127b in FIG. 17) are chamfered in a curved shape. By this chamfering, it is possible to prevent the recording sheet S from being scratched by rubbing the corner of the tip portion 127c against the recording sheet S. Further, the corners of the extending portion γ of the tip of the sheet metal forming the main body portion (127c of FIG. 17) of the bending imparting portion are also chamfered in a curved shape. As a result, even when the stiff recording sheet S bends the tip portion 127c and comes into contact with the main body portion, the recording sheet S is not rubbed by the corners of the main body portion. Therefore, it is possible to avoid the occurrence of scratches on the recording sheet S due to rubbing the stiff recording sheet S with the corners of the main body made of sheet metal. In particular, even if the recording sheet S is rubbed against the main body made of sheet metal when the operator pulls the strong recording sheet S strongly and takes it out of the machine during jam processing of the strong recording sheet S, the recording sheet can be used. Since the corners of the sheet metal are not touched, it is possible to avoid the occurrence of scratches.

As shown in FIG. 13, in this printer, the guide unit plate 127 contacts different points in the direction orthogonal to the sheet transport direction (arrow direction in the figure) of the recording sheet S (hereinafter referred to as the transport orthogonal direction). Two bending-imparting portions 127b are provided. As a result, two wrinkles arranged in the direction orthogonal to the transport are generated with respect to the recording sheet S, thereby inhibiting the wrinkling formation of the recording sheet S with a stronger force. Therefore, the occurrence of creases in the recording sheet S can be suppressed more reliably.

By the way, if the wrinkles generated in the recording sheet S due to the bending applied by the deflection imparting portion 127b are allowed to enter the separation nip, the recording sheet S may be creases. The bending imparting portion 127b provided for avoiding the occurrence of creases may rather promote the occurrence of creases. Therefore, this printer adopts the following configuration. That is, in FIG. 10, only the columnar roller portion of the separation roller 121 is drawn. One of the two bending-imparting portions 127b is provided at a position deviated from the roller portion of the separation roller 121 toward one end side (right side in the drawing) in the rotation axis direction (arrow B direction). The other is provided at a position deviated from the roller portion of the separation roller 121 to the other end side (left side in the drawing) in the direction of the rotation axis. By arranging the two bending-imparting portions 127b in this way, the two wrinkles generated on the sheet by the bending-imparting portion 127b in FIG. 13 are both located outside the separation nip in the rotation axis direction. As a result, it is possible to avoid the occurrence of creases caused by the wrinkles generated on the sheet by the bending imparting portion 127b and entering the separation nip.

As shown in FIG. 16, in the guide unit plate 127, the extending direction of the guide portion, which is the tip portion of the separation nip guide portion 127a, and the extending direction of the tip portion 127d of the bending imparting portion 127b are different from each other. By making the extending directions different from each other in this way, the following two functions can be satisfactorily exhibited with respect to the guide unit plate 127. That is, it is a function of guiding the recording sheet S to the separation nip with respect to the separation nip guide member 127a, and a function of generating a sheet wrinkle for preventing the sheet wrinkling on the recording sheet S by the bending giving portion 127b. In this printer, these two functions are performed by laying the guide portion, which is the tip portion of the separation nip guide portion 127a, closer to the horizontal direction than the extending direction of the tip portion 127d of the deflection imparting portion 127b. Each of them is independent and works well.

So far, we have explained three types of non-feeding that may occur in this printer: "non-feeding due to pushback", "non-feeding due to bumping", and "non-feeding due to slipping". Non-feeding may also occur. "Non-feed due to sheet curl". As shown in FIG. 20, this "non-feed due to sheet curl" means that both ends of the paper cassette in the direction orthogonal to the transport direction (arrow direction in the figure) of the recording sheet S are in the vertical direction from the center. It is generated by curling so that it protrudes above. Immediately after the recording sheet S curled in this way is sent out from the paper cassette 100, as shown in FIG. 21, both ends protruding upward are abutted against the paper feed roller unit case 39. It becomes difficult to move toward the separation nip. This causes "non-feeding due to sheet curl".

Therefore, in this printer, as shown in FIG. 22, a curl correction body 104 is provided on the movable bottom plate 101 of the paper feed cassette 100. The curl straightening body 104 is arranged so as to project upward from the sheet mounting surface of the movable bottom plate 101, and is in a direction orthogonal to the sheet feeding direction (arrow direction in the drawing) of the recording sheet S in the paper feed cassette 100. It contacts the central part (hereinafter referred to as the feeding orthogonal direction). By this contact, the central portion of the recording sheet S in the direction orthogonal to the feeding is pushed upward to correct the curl of the recording sheet S.

When the curl straightening body 104 is not provided, as shown in FIG. 23, both ends of the tip end portion of the recording sheet S in the paper feed cassette 100 in the feeding orthogonal direction project upward from the sheet mounting surface. ing. Then, the protruding portion abuts on the feeding roller unit case. On the other hand, when the curl correction body 104 is provided as in the present printer, as shown in FIG. 24, the tip end portion of the recording sheet S housed in the paper feed cassette 100 is sent out in the orthogonal direction. The entire area is in close contact with the sheet mounting surface. By being sent out from the paper feed cassette 100 in this state, it becomes possible to enter the separation roller without hitting the feeding roller unit case.

As shown in FIG. 25, the curl straightening body 104 is configured to be removable from the movable bottom plate 101. Further, as shown in FIG. 26, in a state of being engaged with the movable bottom plate 101, the slide moves along the sheet feeding direction (direction of arrow A in the figure) and the opposite direction while being held by the movable bottom plate 101. ing. Further, as shown in FIG. 27, there are three engaging portions that engage with the movable bottom plate 101: a first engaging portion 104a, a second engaging portion 104b, and a third engaging portion 104c. There is. The first engaging portion 104a is engaged with the movable bottom plate 101 so as to minimize the amount of protrusion from the seat mounting surface of the curl straightening body 104 in the state of being engaged with the movable bottom plate 101 among the three engaging portions. It fits. Further, the second engaging portion 104b is movable so as to make the amount of protrusion from the seat mounting surface of the curl straightening body 104 in the state of being engaged with the movable bottom plate 101 of the three engaging portions the second smallest. It engages with the bottom plate 101. Further, the third engaging portion 104c has the movable bottom plate 101 so as to maximize the amount of protrusion from the seat mounting surface of the curl straightening body 104 in the state of being engaged with the movable bottom plate 101 among the three engaging portions. It engages with.

The degree to which the curl straightening body 104 corrects the posture of the recording sheet S varies depending on the position of the curl straightening body 104 in the sheet feeding direction on the movable bottom plate 101 and the amount of protrusion of the curl straightening body 104 from the sheet mounting surface. .. Then, as shown in FIG. 24, if the entire region of the tip of the recording sheet S housed in the paper feed cassette 100 in the feeding orthogonal direction is brought into close contact with the sheet mounting surface, the recording sheet S is formed. It is possible to avoid hitting the feed roller unit case. That is, it is possible to avoid the occurrence of "non-feed due to the end". However, in order to correct the posture of the recording sheet S to the posture shown in FIG. 24, it is necessary to set the position and the amount of protrusion to a value corresponding to the strength of the waist of the recording sheet S. Therefore, since the curl straightening body 104 is engaged with the movable bottom plate 101 so as to be slidable as shown in FIG. 26, and a plurality of engaging portions are provided on the curl straightening body 104 as shown in FIG. 27. is there. As a result, the position and the amount of protrusion can be finely adjusted to values commensurate with the strength of the waist of the recording sheet S, and the occurrence of "non-feed due to abutment" can be reliably avoided.

FIG. 28 is a perspective view showing a modified example of the curl straightening body 104 together with the movable bottom plate 101 and the like. As shown in the drawing, a rotatable roller 104d may be provided on the curl straightening body 104 and pressed against the recording sheet S from below in the direction of gravity. When the lowermost recording sheet S is sent out from the paper feed cassette, the roller 104d is driven to rotate following the movement of the recording sheet S, thereby avoiding rubbing between the curl straightening body 104 and the recording sheet S. As a result, it is possible to avoid an increase in sheet transport resistance and occurrence of scratches due to rubbing.

FIG. 34 is a perspective view showing a main part of the feeding roller 35. The feeding roller 35 includes a resin hub 35a, an elastic layer 35e, and a metal rotating shaft member (not shown). The hub 35a includes an inner ring 35b, an outer ring 35c containing the inner ring 35b, and six ribs 35d extending radially from the outer peripheral surface of the inner ring 35b and connected to the inner circumference of the outer ring 35c. The elastic layer 35e is made of an elastic material such as rubber, and is covered on the outer peripheral surface of the outer ring 35c of the hub 35a. The rotating shaft member (not shown) is rotatably received by bearings (not shown) at both ends in the longitudinal direction in a state of being inserted into the internal space of the inner ring 35b of the hub 35a.

The hub 35a having a hollow rib structure as shown and made of resin can be manufactured at low cost because it is easy to mold. However, due to its light weight, it has a problem that it vibrates at a high frequency with rotation to generate noise. The present inventors prototyped the roller 935 shown in FIG. 35 in order to alleviate the defect. The hub 935a of the roller 935 includes an inner ring 350b and an outer ring 350c, as well as a middle ring 350f arranged between them. The rib 350d extends from the outer peripheral surface of the inner ring 350b and is connected to the inner peripheral surface of the middle ring 350f. The space between the middle ring 350f and the outer ring 350c is a ring-shaped space not provided with the rib 350d, and a metal weight 350g is press-fitted into the space. By increasing the load of the roller 935 by the weight 350 g, the vibration of the feeding roller 935 can be suppressed and the generation of noise can be reduced. Note that FIG. 35 is a side view showing the roller 935 from one end side in the direction of the rotation axis, and does not show the cross section of the roller 935, but the weight 350 g is hatched for easy viewing. The same applies to FIG. 36, which will be described later.

However, with such a configuration, the following new problems have arisen. That is, the roller 935 is versatile, such that a model with a specification that emphasizes noise reduction is used with a weight of 350 g fitted, while a model with a specification that emphasizes weight reduction is used without a weight of 350 g. It is desirable that it is excellent. However, it was found that if 350 g of the weight is not fitted, the weight is easily deformed. Specifically, when the weight 350 g is not fitted, the space between the middle ring 935f and the outer ring 935c becomes hollow. Since it is assumed that a weight of 350 g is put in this hollow, a rib cannot be provided between the middle ring 935f and the outer ring 935c. Therefore, the outer ring 935c is more likely to be deformed in the radial direction as compared with the case where the rib is provided. In particular, when another roller is pressed to form a nip, the outer ring 935c may be deformed so as to gradually fall toward the center of rotation due to the nip pressure. Further, when the weight 350 g is fitted, it is conceivable that the outer ring 935c swells outward due to the press fitting of the weight 350 g, and the outer diameter of the roller 935 is increased.

Therefore, the feeding roller 35 of the printer according to the embodiment does not adopt the configuration provided with the middle wheel 935f like the roller 935, but adopts the following configuration. FIG. 36 is a side view showing a main part of the feeding roller 35 of the present printer from one end side in the direction of the rotation axis. In the feeding roller 35, a weight 35g is fitted between two ribs 35d adjacent to each other. There are a total of six spaces partitioned by the ribs 35d (hereinafter referred to as rib partition spaces), and weights 35 g are placed in each of the three rib partition spaces. In order to prevent an extreme bias in weight, the rib partition space containing the weight 35 g and the rib partition space not containing the weight 35 g are alternately arranged in the rotation direction. In such a configuration, since the outer ring 35c is firmly reinforced by the rib 35d, the outer ring 35c is not deformed even when the weight 35g is not fitted. Therefore, the versatility of the feeding roller 35 can be increased. Further, even when the weight 35g is fitted, the outer ring 35c reinforced by the rib 35d does not bulge outward, so that it is possible to avoid an increase in the outer diameter of the feeding roller 35.

FIG. 37 is an enlarged configuration diagram showing an enlarged weight of 35 g. The arrow A direction in the figure indicates the rotation direction of the feeding roller (not shown). Further, the arrow B direction in the figure indicates the direction of the rotation axis. The weight 35 g is provided with protrusions z at both ends in the rotation direction. The protrusion z extends over the entire area of the weight 35 g in the direction of the rotation axis.

FIG. 38 is a partial side view showing the rib partition space of the feeding roller 35 in a partially enlarged manner. It is desirable that the weight of 35 g is firmly fixed so as not to rattle in the rib partition space. Since a force acting in the centrifugal direction acts on the weight 35g in the rib partition space, if the weight 35g is fixed at a position separated from the inner peripheral surface of the outer ring 35c, the weight 35g will be affected by the large centrifugal force. There is a risk of breaking the fixation. Therefore, the weight 35 g is fixed in close contact with the inner peripheral surface of the outer ring 35c. Specifically, in the figure, Lb indicates the distance between the protrusion position ribs. This is the position where one of the two protrusions (z) of the weight 35g placed in the rib partition space contacts one of the two ribs 35d forming the rib partition space, and the other protrusion is the other rib. It is the distance from the position where it contacts 35d. Further, in the figure, La indicates the distance between the protrusions as the distance between the tip of one protrusion and the tip of the other protrusion. As shown in the figure, the inter-projection distance La is larger than the inter-projection rib distance Lb. In the figure, for convenience, a state in which the protrusions are made to bite into the rib 35d is drawn, but in reality, the distance between the protrusions is Lb due to the bending of the ribs 35d rather than such biting. A weight of 35 g having a larger distance between protrusions La can be accommodated in the rib partition space. As a result, 35 g of the weight is firmly fitted in the rib space without rattling. Even if the number of protrusions is only one, the weight 35g can be firmly fitted in the partition space by forming the weight 35g in a shape that allows the protrusions to reliably abut against the rib 35d. is there.

It is desirable that the protrusion is provided at a position of the rib 35d so as to abut against the central portion in the radial direction of the roller. By doing so, the rib 35d can be easily bent by the abutting of the protrusions, and the fixing operability of the weight 35g can be improved. Further, by bending the rib 35d relatively large by the abutment of the protrusion, the weight 35g can be fixed in the rib partition space without rattling regardless of the expansion and contraction of the weight 35g due to the temperature change.

For the convenience of bending the rib 35d by abutting the weight 35g, it is desirable that the rib partition space arranged next to the rib partition space in which the weight 35g is inserted is an empty space in which the weight 35g is not inserted. Further, it is desirable that the rib partition space in which the weight 35 g is inserted and the partition space in which the weight 35 g is not inserted are alternately arranged with the aim of making the weight balance in the circular direction as uniform as possible. Then, in order to realize them at the same time, it is desirable that the number of rib partition spaces is an even number.

In FIG. 38, the resin hub includes a gate circular portion 35h generated during molding. Even when such a gate circle 35h is generated, as shown in the figure, by forming the weight 35g in a shape that avoids it, the weight 35g is not removed by cutting or the like. Can be set in the rib partition space. A sub-rib that bridges between the ribs 35d adjacent to each other may be provided to partition the rib partition space into an inner space and an outer space in the radial direction. In this case, it is desirable to put a weight of 35 g in the outer space with the aim of obtaining a relatively large noise reduction effect with a relatively small weight of 35 g.

As shown in FIG. 37, it is desirable that the protrusion of the weight 35 g extends over the entire area in the direction of the rotation axis of the weight 35 g. By doing so, when the weight 35g is inserted into the rib partition space, the protrusion is not caught on the rib 35d during the insertion, so that the insertability of the weight 35g can be improved.

FIG. 39 is a side view showing a main part of the feeding roller 35 of the printer according to the modified example from one end side in the rotation axis direction. In this feeding roller 35, the weight 35g is not provided with a protrusion, and a gap is formed between the weight 35g in close contact with the outer ring 35c and the two ribs 35d. By filling the gap with the adhesive 35i, the weight 35 g is fixed to the rib 35d. As the adhesive 35i, one having elasticity after curing is used, which has a property of preventing peeling due to a difference in shrinkage rate between the metal body and the hub of the resin material due to environmental changes.

The above description is an example, and the present invention exerts a peculiar effect in each of the following aspects.
[Aspect A]
Aspect A is a sheet accommodating means (for example, a paper cassette 100) for accommodating a recording sheet (for example, recording sheet S) inside itself, and a feeder (for example, a feeder to which the recording sheet accommodated in the sheet accommodating means is pressed. For example, while sandwiching the recording sheet sent out from the sheet accommodating means by the surface movement of the feeding roller 35) between the separating nips due to the contact between the feeding body and the separating body (for example, the separating roller 121), the recording sheet is inserted in the separating nip. A separate feeding means (for example, a combination of a feeding roller 35 and a separating roller unit 120) for separating only a recording sheet that is in direct contact with the feeder among a plurality of overlapping recording sheets, and the separated feeding means. In an image forming apparatus including an image forming means for forming an image on a recording sheet separated into one by a feeding means, the recording sheet before entering the separation nip is bent by its own contact to form the recording sheet. A bending-imparting body (for example, a bending-imparting portion 127b) that generates wrinkles extending along the transport direction is provided, and a flexible member (for example, 127d) is provided at the tip portion (for example, 127d) of the bending-imparting body that contacts the recording sheet. For example, it is characterized in that it is composed of a resin sheet).

In such a configuration, in the pickupless image forming apparatus, wrinkles extending along the transport direction are generated on the recording sheet before the deflection imparting body enters the separation nip, thereby being orthogonal to the transport direction on the recording sheet. Inhibits the occurrence of deflection in the direction of bending. The waviness of the recording sheet as shown in FIG. 31 is caused by the recording sheet causing bending in a direction orthogonal to the transport direction at a plurality of locations. The outbreak is inhibited. In this way, by inhibiting the occurrence of waviness of the recording sheet around the separation nip, it is possible to suppress the occurrence of creases of the recording sheet having a weak waist.

Further, in the aspect A, when the tip portion of the flexible member of the deflection imparting body comes into contact with the recording sheet having a strong waist in front of the separation nip, it flexibly bends, so that the deflection imparting body in front of the separation nip Reduce the amount of lifting of the recording sheet. As a result, the area where the recording sheet is pressed against the surface of the feeder on the front side of the separation nip is reduced, and the occurrence of slip on the surface of the feeder of the stiff recording sheet is suppressed, resulting in slippage. It is possible to suppress the occurrence of non-feeding of the recording sheet.

[Aspect B]
In the aspect B, in the aspect A, the bending imparting body is arranged so that the tip end portion is brought into contact with the recording sheet before entering the separation nip from below in the direction of gravity, and the entire area of the bending imparting body is arranged. Of these, only the tip portion is projected upward in the direction of gravity from the inside of the sheet accommodating means toward the separation nip of the recording sheet. In such a configuration, as described in the embodiment, the tip portion of the deflection imparting body ensures that wrinkles extending in the transport direction are generated on the recording sheet, and the occurrence of “non-feed due to slip” is surely suppressed. Can be done.

[Aspect C]
In aspect C, in aspect B, at least the main body forming member (for example, sheet metal) forming the main body and the tip forming member (for example, a resin sheet) forming the tip portion while being fixed to the main body cause the bending. It is characterized by forming an grantor. In such a configuration, as described in the embodiment, the desired flexibility can be easily exhibited as designed with respect to the tip end portion of the deflection imparting body.

[Aspect D]
In aspect D, in aspect C, the rising portion (for example, the rising portion α) that rises from the lower side to the upper side in the gravity direction and the separation nip from the side of the sheet accommodating means in the sheet transport direction at the position of the upper end of the rising portion. A combination of a refracting portion that refracts toward the side (for example, the refracting portion β) and a tip extending portion (for example, the tip extending portion γ) extending from the refracting portion toward the tip side is combined in the bending imparting body. Each of the main body forming member and the tip forming member is provided, and the rising portion of the main body forming member is accommodated on the surface on the separation nip side in the sheet conveying direction of the rising portion of the tip forming member in the sheet conveying direction of the rising portion. The surface of the main body forming portion is fixed, and the tip extending portion of the tip forming member is positioned below the tip extending portion of the main body forming member in the direction of gravity. It is characterized in that it is supported by the refracting portion of the tip portion forming member without being fixed to the tip extending portion. In such a configuration, as described in the embodiment, the tip portion of the bending imparting body is flexed satisfactorily as compared with the case where the tip extending portion of the tip forming member is attached to the lower surface of the tip extending portion of the main body forming portion. You can do it. As a result, the occurrence of "non-feed due to slip" can be satisfactorily suppressed.

[Aspect E]
Aspect E is characterized in that, in any one of aspects A to D, a plurality of the flexure-imparting bodies that come into contact with different points in a direction orthogonal to the transport direction of the recording sheet are provided as the flexure-imparting body. Is. In such a configuration, the plurality of deflection imparting bodies generate a plurality of wrinkles arranged in the direction orthogonal to the transport with respect to the recording sheet, thereby hindering the wrinkling formation of the recording sheet with a stronger force, and thus the generation of creases in the recording sheet. Can be suppressed more reliably.

[Aspect F]
In aspect F, in aspect E, a rotatable separation roller is used as the separation body, and at least one of the deflection imparting bodies is displaced from the columnar roller portion of the separation roller to one end side in the rotation axis direction. It is characterized in that at least one of the bending imparting bodies is provided at a position deviated from the roller portion to the other end side in the rotation axis direction. In such a configuration, as described in the embodiment, it is possible to suppress the occurrence of creases in the recording sheet due to the sheet wrinkles generated by the flexible granting body.

[Aspect G]
In any of aspects A to F, the aspect G prevents the recording sheet from hitting the separated body before entering the separation nip by contacting the recording sheet before entering the separation nip. It is characterized in that a separation nip guide body (for example, a separation nip guide portion 127a) for guiding the recording sheet toward the separation nip is provided. In such a configuration, as described in the embodiment, the occurrence of "non-feed due to abutting" can be avoided by preventing the abutting of the recording sheet against the separating body by the separating nip guide.

[Aspect H]
Aspect H is characterized in that, in Aspect G, the extending direction of the guide portion of the separated nip guide body and the extending direction of the tip portion of the bending imparting body are different from each other. In such a configuration, as described in the embodiment, the following two functions can be independently exerted satisfactorily. That is, it is a function of guiding the recording sheet to the separation nip with respect to the separation nip guide body, and a function of generating a sheet wrinkle for preventing the sheet wrinkling on the recording sheet by the bending imparting body.

[Aspect I]
Aspect I is arranged so as to project from the sheet mounting surface of the sheet accommodating means in any of aspects A to H, and is centered in a direction orthogonal to the sheet feeding direction of the recording sheet in the sheet accommodating means. A curl straightening body (for example, a curl straightening body 104) that corrects the curl of the recording sheet by contacting the portion is provided detachably from the sheet accommodating means. In such a configuration, as described in the embodiment, the occurrence of "non-feed due to sheet curl" can be suppressed.

[Aspect J]
In the aspect J, in the aspect I, a plurality of engaging portions (for example, the first engaging portion 104a) that engage with the sheet accommodating means so as to make the amount of protrusion of the curl straightening body from the sheet mounting surface different from each other. , The second engaging portion 104b, the third engaging portion 104c) is provided on the curl straightening body. In such a configuration, as described in the embodiment, the amount of protrusion of the curl straightening body from the sheet mounting surface is finely adjusted to a value commensurate with the strength of the waist of the recording sheet, and “non-feeding due to abutting” occurs. Can be reliably avoided.

[Aspect K]
In any of aspects A to J, the mode K includes an inner ring (for example, an inner ring 35b), an outer ring containing the inner ring (for example, an outer ring 35c), and an outer ring extending radially from the outer circumference of the inner ring as the feeder. A rotatable feeding rotating body (for example, feeding roller) including a plurality of ribs (for example, rib 35d) connected to the inner circumference and an elastic layer (for example, elastic layer 35e) made of an elastic body coated on the outer periphery of the outer ring. 35) is used to fix a weight (for example, 35 g) in a space between a plurality of ribs arranged inside the outer ring. In such a configuration, as described in the embodiment, the versatility of the feeding rotating body can be enhanced, and the expansion of the outer diameter of the feeding rotating body due to the insertion of a weight can be avoided.

[Aspect L]
Aspect L is a mode K, wherein the weight has protrusions on one end surface and the other end surface in the direction of rotation of the feeding and rotating body, and one of the two ribs is located at a position sandwiching the space. In a size and shape that one of the protrusions is brought into contact with the rib, the other protrusion is brought into contact with the rib of the other, and a portion of the weight different from the two protrusions is brought into contact with the inner peripheral surface of the outer ring. It is characterized by being. With such a configuration, it is possible to avoid rattling of the weight in the space.

[Aspect M]
In the aspect M, in the aspect L, the distance between the protrusion position ribs that linearly connects the contact position with the protrusion on one of the two ribs and the contact position with the protrusion on the other rib is set in the two ribs. It is characterized in that it is smaller than the distance between the tips. In such a configuration, the weight can be press-fitted into the space and firmly fixed.

[Aspect N]
Aspect N is characterized in that, in the aspect M, the protrusion is extended over the entire area in the direction of the rotation axis of the feeder in the weight. In such a configuration, when the weight is inserted into the space between the ribs, the protrusion is not caught on the rib during the insertion, so that the insertability of the weight can be improved.

[Aspect O]
Aspect O is characterized in that, in Aspect K, the weight is fixed to the rib by an adhesive. In such a configuration, the weight can be fixed to the rib without deforming the rib by press-fitting the weight.

[Aspect P]
Aspect P is characterized in that, in any one of aspects KO, the weight is shaped so as to avoid a gate portion formed during molding of the inner ring, the outer ring, and the hub provided with the rib. is there. In such a configuration, the manufacturing cost can be suppressed by putting the weight in the space of the feeding rotating body without removing the gate portion by cutting or the like.

1: Photoreceptor (part of image forming means)
2: Cleaning blade (part of image forming means)
3: Recovery screw (part of image forming means)
4: Charging roller (part of image forming means)
7: Latent image writing device (part of image forming means)
8: Developing device (part of image forming means)
9: Toner cartridge (part of image forming means)
10: Transfer roller (part of image forming means)
35: Feeding roller (feeder, part of separate feeding means)
100: Paper cassette (sheet accommodating means)
104: Curl straightening body 104a: First engaging portion 104b: Second engaging portion 104c: Third engaging portion 120: Separation roller unit (part of separation feeding means)
127: Guide unit plate 127a: Separate nip guide (separate nip guide)
127b: Flexibility imparting portion (deflection imparting body)
127c: Main body 127d: Tip α: Rising part β: Refractive part γ: Tip extending part S: Recording sheet

Japanese Unexamined Patent Publication No. 6-255810

The present invention, a sheet over preparative, a sheet Okukarada and separation body and an image forming apparatus for separating one by separation nip contact.

The present invention has been made in consideration of the above background, it is an object while suppressing the occurrence of weak stone over preparative folds waist, not feeding waist strong stone over preparative generation that is to provide the images forming apparatus that can have suppressed.

To achieve the above object, the present invention provides a sheet in which the sheet Okukarada and separation body directly contact with though Resid over preparative before Symbol supply Okukarada in separation nip contact contacts the direct in separation and images forming device you and feeding a sheet of non-contact from below sheet over preparative at different locations in the width direction orthogonal to the conveying direction of the sheet by the separating sheet conveyance direction upstream side of the nip A flexible tip forming member that forms a plurality of tip portions, and a separation nip guide portion that guides the sheet toward the separation nip by contacting the sheet on the upstream side in the sheet transport direction from the separation nip. The sheet is provided so that the tip of the sheet comes into contact with the sheet from below at a position outside the separation nip in the width direction of the sheet, outside the plurality of tips, and downstream of the tips in the sheet transport direction. than the width direction and is characterized in the this sheet conveying direction is provided a long protrusion.

According to the present invention, the images forming apparatus, while suppressing the occurrence of weak stone over preparative folds waist, there is an excellent effect that it is possible to suppress the occurrence of non-feeding waist strong stone over preparative ..

As shown in FIG. 18, the sheet metal for forming the main body portion 127c of the bending imparting portion 127b and the resin sheet for forming the tip portion 127d have a rising portion α, a refracting portion β, and a refracting portion β, respectively. The tip extending portion γ is provided. The rising portion α is a portion that rises from the lower side to the upper side in the direction of gravity. Further, the refracting portion β is a portion that refracts from the paper feed cassette side to the separation nip side in the sheet transport direction at the position of the upper end of the rising portion α. Further, the tip extending portion γ is a portion extending from the refracting portion β toward the tip side in contact with the recording sheet S.

FIG. 19 is a side view showing the guide unit plate 127. In the figure, the direction Cow direction from the left side in the figure to the right side is a sheet conveyance direction. The region on the right side of the guide unit plate 127 in the drawing is the region on the separation roller side with the guide unit plate 127 in the sheet transport direction as a boundary. The area on the left side of the guide unit plate 127 in the drawing is the area on the paper feed cassette side with the guide unit plate 127 in the sheet transport direction as a boundary. On the surface on the separation nip side of the rising portion α of the sheet metal serving as the main body forming member, the surface on the paper feed cassette side at the rising portion α of the resin sheet serving as the tip forming member is fixed by the double-sided tape 127e. Further, the surface of the resin sheet on the rising portion α on the separation roller side is fixed to the upper cover (126 in FIG. 8) of the separation roller unit by double-sided tape 127f. By fixing them, the tip portion (127d) made of the resin sheet of the bending imparting portion (127b) is firmly fixed to the main body portion (127c) made of sheet metal.

However, the tip extending portion γ of the resin sheet is not fixed to the sheet metal or other members. The tip extending portion γ of the resin sheet is supported by the refracting portion β of the resin sheet in a state of being located below the tip extending portion γ of the sheet metal in the direction of gravity. As a result, the tip extending portion γ of the resin sheet that functions as the tip portion 127d of the bending imparting portion 127b can freely swing (bend) around the refracting portion β of the resin sheet. Then, it is possible to the distal end extension γ of the resin sheet in comparison to paste on the lower surface of the distal end extension γ of sheet metal, to deflect the good tip 12 7d. Further, when the tip extending portion γ of the resin sheet is attached to the lower surface of the tip extending portion γ of the sheet metal, the tip extending portion γ and the rising portion α of the resin sheet are bound to the bending portion β of the resin sheet. Will be attached to each sheet metal, but in this case, the work efficiency will be significantly deteriorated. By setting the place where the resin sheet is attached to one place of the rising portion α, deterioration of work efficiency can be avoided.

[Aspect D]
In aspect D, in aspect C, the rising portion (for example, the rising portion α) that rises from the lower side to the upper side in the gravity direction and the separation nip from the side of the sheet accommodating means in the sheet transport direction at the position of the upper end of the rising portion. A combination of a refracting portion that refracts toward the side (for example, the refracting portion β) and a tip extending portion (for example, the tip extending portion γ) extending from the refracting portion toward the tip side is combined in the bending imparting body. Each of the main body forming member and the tip forming member is provided, and the rising portion of the main body forming member is accommodated on the surface on the separation nip side in the sheet conveying direction of the rising portion of the tip forming member in the sheet conveying direction of the rising portion. The surface of the main body forming portion is fixed, and the tip extending portion of the tip forming member is positioned below the tip extending portion of the main body forming member in the direction of gravity. tip is characterized in that said by cantilever Chi supported refractive portion of the tip forming member without fixing the extending portion. In such a configuration, as described in the embodiment, the tip portion of the bending imparting body is flexed satisfactorily as compared with the case where the tip extending portion of the tip forming member is attached to the lower surface of the tip extending portion of the main body forming portion. You can do it. As a result, the occurrence of "non-feed due to slip" can be satisfactorily suppressed.

Claims (12)

A sheet accommodating means for accommodating a recording sheet inside itself,
While sandwiching the recording sheet sent out from the inside of the sheet accommodating means by the surface movement of the feeder against which the recording sheet accommodated in the sheet accommodating means is pressed, the recording sheet is sandwiched between the separation nips due to the contact between the feeder and the separator. A separate feeding means for separating only the recording sheets that are in direct contact with the feeder among the plurality of recording sheets that are overlapped in the separation nip.
In an image forming apparatus including an image forming means for forming an image on a recording sheet separated into one by the separated feeding means.
The recording sheet before entering the separation nip is bent by its own contact, and the recording sheet is provided with a deflection imparting body that generates wrinkles extending along the transport direction.
Moreover, the image forming apparatus is characterized in that the tip portion of the bending body that comes into contact with the recording sheet is made of a flexible member. In the image forming apparatus of claim 1,
The flexure imparting body is arranged so that the tip portion is brought into contact with the recording sheet before entering the separation nip from below in the direction of gravity, and only the tip portion of the entire area of the flexure imparting body is formed. An image forming apparatus characterized in that the recording sheet is projected upward in the direction of gravity from the inside of the sheet accommodating means toward the separation nip. In the image forming apparatus of claim 2,
An image forming apparatus characterized in that the bending imparting body is formed by at least a main body forming member forming the main body and a tip forming member forming the tip portion while being fixed to the main body. In the image forming apparatus of claim 3,
From the rising portion that rises from the lower side to the upper side in the direction of gravity, a refracting portion that refracts from the side of the sheet accommodating means in the sheet conveying direction toward the side of the separation nip at the position of the upper end of the rising portion, and the refracting portion. A combination with the tip extending portion extending toward the tip side is provided on the main body forming member and the tip forming member of the bending imparting body, respectively.
The surface of the tip forming member on the sheet receiving means side in the sheet transporting direction of the tip forming member is fixed to the surface of the rising portion of the main body forming member on the separation nip side in the sheet transporting direction.
Moreover, the tip extending portion of the tip forming member is not fixed to the tip extending portion of the main body forming portion in a state of being positioned below the tip extending portion of the main body forming member in the direction of gravity. An image forming apparatus characterized in that the refracting portion of the tip forming member is supported by the refracting portion. In the image forming apparatus according to any one of claims 1 to 4,
An image forming apparatus characterized in that, as the deflection imparting body, a plurality of the deflection imparting bodies that come into contact with different points in a direction orthogonal to the transport direction of the recording sheet are provided. In the image forming apparatus of claim 5,
A rotatable separation roller was used as the separator.
At least one of the bending-imparting bodies is provided at a position shifted to one end side in the rotation axis direction from the columnar roller portion of the separation roller, and at least one other bending-imparting body is provided on the rotation axis of the roller portion. An image forming apparatus characterized in that it is provided at a position shifted to the other end side in the direction. In the image forming apparatus according to any one of claims 1 to 6,
By contacting the recording sheet before entering the separation nip, the recording sheet is guided toward the separation nip while preventing the recording sheet from hitting the separated body before entering the separation nip. An image forming apparatus characterized in that a separate nip guide is provided. In the image forming apparatus of claim 7,
An image forming apparatus characterized in that the extending direction of the guide portion of the separated nip guide body and the extending direction of the tip portion of the bending imparting body are different from each other. In the image forming apparatus according to any one of claims 1 to 8.
The curl of the recording sheet is corrected by being arranged so as to protrude from the sheet mounting surface of the sheet accommodating means and contacting the central portion of the recording sheet in the sheet accommodating means in the direction orthogonal to the sheet feeding direction. An image forming apparatus characterized in that a curl straightening body is provided detachably from the sheet accommodating means. In the image forming apparatus of claim 9,
An image forming apparatus characterized in that the curl straightening body is provided with a plurality of engaging portions each engaged with the sheet accommodating means so that the amount of protrusion of the curl straightening body from the sheet mounting surface is different from each other. .. In the image forming apparatus according to any one of claims 1 to 10.
The feeder includes an inner ring, an outer ring including the inner ring, a plurality of ribs extending radially from the outer circumference of the inner ring and connecting to the inner circumference of the outer ring, and an elastic body coated on the outer circumference of the outer ring. An image forming apparatus characterized in that a rotatable feeding rotating body provided with a layer is used, and a weight is fixed in a space between a plurality of the ribs arranged inside the outer ring. The image forming apparatus according to claim 11.
The weight has protrusions on one end surface and the other end surface in the rotation direction of the feeding rotating body, and one of the two protrusions is brought into contact with the two ribs located at positions sandwiching the space, and the other. An image forming apparatus having a size and shape in which the other protrusion is brought into contact with the rib of the above, and a portion of the weight different from the two protrusions is brought into contact with the inner peripheral surface of the outer ring.

Images