JP2001010131A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus in which a recording medium or a sheet feed roller is not subjected to deformation even if the imaging apparatus is not used for a long term and left as it is. SOLUTION: When a roll sheet 14a is under feed, a pulley 174 is separated from a leaf spring 178 and a sheet feed roller 76 comes into press contact with the surface of the roll sheet 14a. Upon ending sheet feed, an electromagnetic clutch 162 is disconnected and an electromagnetic clutch 164 is connected. A drive motor 156 is driven under that state to turn a pulley 174 by 90 deg. in the direction of arrow B. Consequently, the long diametral part of the pulley 174 pushes down the leaf spring 178 and a waiting roller 180 moves downward to touch the outer circumferential surface of the roll sheet 14a. An upper sheet feed plate 152 thereby floats correspondingly and the sheet feed roller 76 is separated from the outer circumferential surface of the roll sheet 14a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus for forming an image on a recording medium such as roll paper or cut paper.

[0002]

2. Description of the Related Art As an output device of a computer or a work station, an ink jet type image forming apparatus for forming an image on a recording medium by discharging ink, or an electrophotographic type forming apparatus for forming an image on a recording medium using a developer or the like. Image forming apparatuses are known. Some of these image forming apparatuses can selectively use both a cut sheet cut in advance (cut) into a predetermined size and a roll-shaped recording medium in which the recording medium is wound in a roll shape. Further, there is a type in which only a roll-shaped recording medium can be used as a recording medium.

Referring to FIGS. 3 to 5, a conventional plotter (an example of an ink jet type image forming apparatus) which can selectively use both a cut sheet and a roll-shaped recording medium.
Will be described.

FIG. 3 is a side view schematically showing a conventional plotter, and FIG. 4 is a side view schematically showing a plotter obtained by improving the plotter shown in FIG. FIG. 5 is a side view schematically showing a type of plotter in which two roll-shaped recording media can be set at the same time.

As shown in FIG. 3, in a plotter 10, a roll paper 14 (an example of a roll-shaped recording medium) is generally provided slightly below (obliquely behind) an image forming area 12 where an image is formed on the recording medium. .) Is placed. To form an image on the roll paper 14, the leading end 14 ′ of the roll paper 14 is pulled out, inserted into the insertion slot 16,
Send to 8. Thereafter, the carriage 22 on which the print head 20 is mounted is moved in the main scanning direction (a direction perpendicular to the plane of FIG. 3).
While reciprocating, the ink is ejected onto the portion of the roll paper 14 located in the image forming area to form an image.

When an image is to be formed on the cut sheet 24, the cut sheet 24 is inserted from the cut sheet insertion port 26 on the opposite side of the insertion port 16 and sent to the transport roller 18. in this case,
To feed the cut paper 24 to the transport roller 18, the leading end 14 ′ of the roll paper 14 is removed from the transport roller 18. When forming an image on the roll paper 14 after forming an image on the cut paper 24, the user (operator) may
4 is manually fed into the conveying roller 18 by hand. Thus, preparation for forming an image on the roll paper 14 instead of the cut paper 24 is completed.

However, in the plotter 10 having such a configuration, when the user wants to use the roll paper 14 after using the cut paper 24, the user needs to go near the plotter 10 and replace the recording paper. Therefore, in the plotter 10,
Remote operation that is compatible with the PC network cannot be performed.

Therefore, in order to enable the above remote control, a plotter 30 of the type shown in FIG. 4 has been proposed. In this plotter 30, a pair of feed rollers 32
The roll paper 14 is conveyed while being pinched between the rollers a and 32b, and is sent to the conveying rollers 18. Then, the feed roller 32
The roll paper 14 is conveyed to the image forming area 12 by rotating both the rollers a and 32b and the conveying roller 18 (forward rotation) to form an image. When an image is formed on the cut sheet 24, a cut sheet mode signal is sent to a controller (not shown) of the plotter 30, and the feed rollers 32a and 32b and the transport roller 18 are sent.
By rotating both of them in reverse, the roll paper 14 is rewound to a position where the leading end 14 ′ of the roll paper 14 does not obstruct the path of the cut paper 24, and the feed rollers 32 a and 32 b sandwich the leading end 14 ′ of the roll paper 14. Put it in the waiting state.

When an image is to be formed on the roll paper 14, a signal of the roll paper mode is sent to the above-described controller, and both the feed rollers 32a and 32b and the transport roller 18 are rotated forward, and the roll paper is transferred to the image forming area 12. 14 is conveyed. By performing such control, the cut paper mode and the roll paper mode can be automatically switched. Therefore, it is not necessary to set the roll paper 14 every time the user switches the mode.

In the plotter 40 shown in FIG. 5, two roll papers 14, 14 can be set at the same time. In such a type of plotter 40, the feed rollers 32a, 32
b is arranged for each roll paper 14,
One of the roll papers 14 and 14 and the cut paper 24 can be selected and automatically conveyed.

The above three types of plotters 10, 3
In both cases, 0 and 40, the roll paper 14 is placed behind the plotter body, so the roll paper 14
In order to correct the skewing that occurs when the sheet is fed into the printer 8, it is necessary to work around the plotter body. Therefore, the work of correcting the skew is troublesome.

In order to easily correct the skew, the roll paper 1
4 may be placed in front (front) of the plotter body. However, since there are many occasions in which the recording medium on which an image has been formed is often handled in front of the plotter main body, the roll paper 14 is placed behind the plotter main body, and the paper is often ejected in front of the plotter main body. .

When the roll paper 14 is also placed in front of the plotter main body and the paper is discharged in front of the plotter main body, the roll paper inserted from this front is made to make a U-turn and discharged to the front. The paper transport distance becomes longer.
For this reason, paper jams and the like are liable to occur, and it is necessary to increase the number of conveying rollers for conveying the roll paper, which complicates the structure of the plotter. Further, in the case of a configuration in which the roll paper is U-turned, the configuration is not suitable for thick roll paper. Furthermore, a stacker, a basket, a tray, and the like on which the discharged recording medium is loaded are usually placed in front of the plotter main body. However, the loading of the recording medium may be interrupted by roll paper.

Such inconveniences and problems become more prominent in a plotter of the type in which two or more roll papers are set at the same time as shown in FIG. Therefore, the plotter is usually configured to place the roll paper behind the main body.

In a plotter of the type shown in FIGS. 4 and 5, the transport rollers 32a and 32b transport the roll paper 14 while nipping the leading end 14 'thereof.
When the roll paper 14 is fed, the roll paper 14 may not be transported straight but may be transported obliquely and skewed. in this case,
The skew is corrected by separating the feeding rollers 32a and 32b from each other.

The following two methods are known as methods for checking whether or not the roll paper 14 is traveling straight without skew. One method is to visually check whether the roll paper 14 is inclined with respect to a vertical line (a line parallel to the roll paper transport direction) drawn on the front side of the plotter. Another method is to mount a reading sensor for reading the edge in the width direction of the roll paper 14 on the print head 20 and detect skew based on a signal carrying the edge of the roll paper 14 read by the reading sensor. How to

In the former case, it is necessary to move to the front side of the plotter to check the skew. In the latter case, it takes time for the reading sensor to read the end of the roll paper 14 and detect whether or not the paper is skewed.

When the width of the roll paper is wide, it is very difficult to grasp the leading end of the roll paper and insert it straight into the roll paper insertion slot 16. Therefore, the inserted roll paper is likely to skew. Further, the leading end of the roll paper is not always perpendicular to the end face in the width direction. Therefore, the roll paper may be skewed even if a registration roller used for transporting the cut paper whose leading end is perpendicular to the end face in the width direction is used for transporting the roll paper. Also, in order for the roll paper to move straight without skew, the roll paper, the feed roller, and the transport roller must be precisely parallelized, so the accuracy of the parts of the plotter becomes extremely high. May be. Therefore, in an apparatus for forming an image on roll paper, it is important to reduce skew when the roll paper is transported.

In the plotter 10 shown in FIG. 3, the fed (pulled out) roll paper 14 is
In order to check the presence or absence of skew by a detection sensor (not shown) fixed to 2, the sheet is further conveyed by conveying rollers 18. For example, in the case of roll paper of A0 size width (840 mm), 6
The paper is fed by about 00 mm, and the amount of deviation of the roll paper side end is detected, and it is determined whether or not the skew is within the allowable range. After this determination, in order to form an image from the leading end of the roll paper, the transport roller is rotated in the reverse direction to rewind the drawn portion of the roll paper.

At the time of the rewinding, the drawn-out portion of the roll paper may be loosened. This slack is often formed near the roll portion of the roll paper that is still wound. Therefore, when no parts or the like are arranged below the roll portion, the slack portion of the roll paper does not cause any obstacle. However, if another roll paper is arranged under the roll portion, the setting of the other roll paper is hindered. Further, for example, in the case of high temperature and high humidity, the roll habit due to slack remains as it is, and when forming (printing) an image,
The landing position of the ink ejected from the print head is displaced and the image is disturbed, or the image is stained by the contact of the print head with the roll paper. Further, the contact may damage the roll paper and the print head.

[0021]

As a plotter capable of eliminating such slack, a plotter 50 as shown in FIG.
Has been proposed.

The plotter 50 has two roll papers 14a,
14b can be mounted simultaneously. In order to mount the roll paper 14a on the plotter 50, the upper paper feed unit 70 is turned upward and opened. This allows
The magnet 74 fixed to the cover 72 is attracted to the magnet receiving plate 52 fixed to the main body of the plotter 50, and the upper paper feed unit 70 remains open, so that the roll paper 14a can be mounted on the plotter 50.

After the roll paper 14a is mounted on the plotter 50, the upper paper feed unit 70 is lowered (closed) while pulling the leading end (one end) of the roll paper 14a in the direction of arrow A and pulling it out. A paper feed roller 76 that feeds the roll paper 14 a into the plotter 50 is disposed near the tip of the upper paper feed unit 70. A part of the paper feed roller 76 protrudes from the guide plate 78, and when the upper paper feed unit 70 is lowered, the protruded part comes into pressure contact with the outer peripheral surface of the roll paper 14a. A weight 80 is fixed near the paper feed roller 76, and presses the roll paper 14a more strongly. The weight 80 is not always necessary, and the weight of the weight 80 is determined according to the pressing force due to the weight of the upper paper feeding unit 70. The paper feed roller 76 also rotates (forward rotation) to pull out the leading end of the roll paper 14a in the direction of arrow A, but also rotates (reverse rotation) in the opposite direction to rewind the roll paper 14a.

The upper paper feed unit 70 rotates about a rotation shaft 82 by an angle within a predetermined range. In the vicinity of the rotation shaft 82, a detection sensor (not shown) for detecting the roll paper 14a is arranged. Roll paper 1
When 4a is detected, a paper feed signal is transmitted to a controller (not shown). For example, after 3 seconds, the paper feed roller 76 starts rotating,
Feeding of the roll paper 14a is started. The weight 80 is used to secure a pressure at which the paper feed roller 76 can pull out the roll paper 14a and feed the paper, and if this pressure is sufficient by the weight of the upper paper supply unit 70, the weight 80
Need not be arranged. Also, even if there is no weight 80, the upper paper feed unit 70 rotates downward by its own weight and
a.

Roll paper 1 pulled out by paper feed roller 76
The leading end of 4 a reaches the flapper 88 through a transport path formed by the guide plate 78 and the lower guide plate 86. The flapper 88 has an arm at its end, and is lifted up when the roll paper 14a passes below it. As a result, the detection sensor 90 is turned on, and the transport roller 18 starts rotating based on the ON signal. The pulled-out portion (pull-out portion) of the roll paper 14 a is further conveyed by the conveying roller 18, passes through the platen 92, and temporarily stops. The stop position where the drawer portion stops is measured based on the detection position of the detection sensor 94.

When the drawing portion of the roll paper 14a stops,
The carriage 22 on which the print head 20 is mounted is reciprocated in a direction (scanning direction) orthogonal to the conveying direction of the draw-out portion, and the width direction of the draw-out portion is detected by a paper detection sensor (not shown) mounted on the carriage 22. Measure (read) edge and width. Thereafter, if the roll paper 14a has a width of, for example, A0 size, the drawn portion is further conveyed by 600 mm,
Measure the width direction end and width of the drawn portion again. Based on the first measurement value and the second measurement value, the skew amount of the drawn portion is calculated. If the skew amount is equal to or less than the predetermined value, the normal state is determined, the drawn portion is retracted by a predetermined amount, and the cutter 22a fixed to the carriage 22 is operated to cut the end of the drawn portion. Thereafter, the leading end of the drawn-out portion is returned to the detection sensor 94, and then advanced to convey the leading end of the drawn-out portion to a predetermined printing start position. If the skew amount exceeds a predetermined value, the conveyance of the roll paper 14a is stopped, and a warning to the user (such as "Please correct the skew") is displayed on the display panel (not shown) of the plotter 50. indicate.

Here, a technique for preventing the drawn portion of the roll paper 14a from becoming loose will be described.

When the roll paper 14a is pulled out or rewound, the feed roller 76 and the transport roller 18 rotate. Therefore, if the transport amount of the paper feed roller 76 and the transport roller 18 is not matched, the drawn-out portion of the roll paper 14a is pulled (tensile work) or slackened. If the extent of pulling or loosening increases, the transport amount of the transport roller 18 becomes inaccurate, or the drawn portion may be bent. To prevent such troubles,
On the guide plate 78 of the upper paper feed unit 70, a looseness detection sensor 96 for detecting looseness of the drawer portion is fixed.

When the pull-out portion is detected by the slack detection sensor 96 (when the pull-out portion is not loose), the transport amount by the paper feed roller 76 is increased. When the pull-out portion is not detected (when the pull-out portion is loose), the feeding is performed. The rotation of the paper roller 76 is stopped to interrupt the paper feeding. To rewind the roll paper 14a, the paper feed roller 76 is rotated in the reverse direction. This allows
The roll paper 14a can be rewound without slack. As described above, since the paper feed roller 76 is rotated while the surface of the roll paper 14a is brought into pressure contact with the paper feed roller 76, the drawn-out portion of the roll paper 14a can be prevented from becoming loose. The lower roll paper 14b attached to the lower paper feed unit 110 can also be prevented from being loosened by the paper feed roller 112 at the portion where the roll paper 14b is pulled out.

The above-mentioned paper feed rollers 76 and 112 are usually made of metal having irregularities on the surface thereof in order to increase the frictional force with the roll papers 14a and 14b.
A roller having metal powder or resin powder adhered to the surface is used. When such a roller is used, if the paper feed rollers 76 and 112 are kept in contact with the roll papers 14a and 14b without using the plotter 50 for a long time, the paper feed rollers 76 and 112 are attached to the roll papers 14a and 14b. , 112 remain or dents are formed. If such marks or dents are formed on the roll paper 14a, 14b, the image quality is degraded or the contact resistance with the guide member is increased to cause paper jam. Further, the peripheral portion of the depression may rise and come into contact with the print head.

The above-mentioned paper feed rollers 76 and 112 may be made of a soft material having a high friction coefficient. In this case, if the plotter 50 is left unused for a long time, the paper feed rollers 76 and 112 are deformed by the weight of the upper paper feed unit 70 and the lower paper feed unit 110, and skew is likely to occur. .

The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus in which a recording medium and a paper feed roller are hardly deformed even if they are not used for a long time.

[0033]

In order to achieve the above object, an image forming apparatus according to the present invention comprises a roll-shaped recording medium wound in a roll shape and a cut sheet cut to a predetermined size. An image forming apparatus for selectively feeding paper into a predetermined image forming area to form an image, (1) an insertion opening, into which the roll-shaped recording medium and the cut sheet are inserted, leading to the image forming area; And (3) a roll-shaped recording medium that is in contact with the outer peripheral surface of the roll-shaped recording medium disposed at a position distant from the insertion slot and feeds the roll-shaped recording medium to the insertion slot while drawing out the roll-shaped recording medium; And a standby member for selectively positioning the paper feed roller at any one of a paper feed position contacting an outer peripheral surface of the paper feeder and a standby position away from the outer peripheral surface. .

Here, (4) the standby member may include a cylindrical standby roller that comes into contact with the outer peripheral surface of the roll-shaped recording medium when the paper feed roller is located at the standby position. Good.

(5) The standby roller may be longer than the length of the paper feed roller.

(6) The standby roller may be made of resin.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view showing an upper paper feed unit to which a standby member is attached, and FIG. 2 is an explanatory view showing the movement of a standby roller. In these drawings, the same components as those shown in FIG. 6 are denoted by the same reference numerals.

The configuration of the plotter of the present invention is the same as the configuration of the plotter 50 shown in FIG. Further, the plotter of the present invention is also provided with a lower paper feed unit (not shown) having the same structure as the upper paper feed unit 150. This lower sheet feeding unit is arranged at the same position as the lower sheet feeding unit 110 of the plotter 50 shown in FIG. Here, the upper paper feeding unit 150 will be described.

The ends of the rotating shafts 82 are rotatably fixed to the left side plate 132 and the right side plate 130 of the plotter body of the present invention. The rotation shaft 82 has a paper feed roller 76
The upper paper feed plate 152 to which the components are fixed is fixed by a stopper 142. A drive motor 156 is fixed to a center portion of the upper paper feed plate 152 in the direction of arrow A (roll paper transport direction). The drive motor 156 is transmitted from a controller (not shown) via a signal line 154. It is driven based on the incoming signal. One end of a rotation shaft 158 of the drive motor 156 is rotatably fixed to an L-shaped fixing plate 160.
The rotating shaft 158 has two electromagnetic clutches 162 and 164.
Are fixed at predetermined intervals. The rotation shaft 158
Extend in a direction perpendicular to the direction of arrow A.

A rotating shaft 166 extends slightly in parallel with the rotating shaft 158 in the direction of arrow A from the rotating shaft 158. Both ends of the rotating shaft 166 are connected to the upper sheet feeding plate 152.
Are rotatably fixed to fixing plates 168 formed at both ends in the width direction (perpendicular to the direction of arrow A). A gear 170 is fixed to a portion of the rotating shaft 166 facing the electromagnetic clutch 164. Electromagnetic clutch 1
A transmission belt 172 that transmits the torque of the drive motor 156 is stretched between the gear 64 and the gear 170. Further, elliptical pulleys 174 are fixed to portions of the rotary shaft 166 slightly inside from both ends.

Below each pulley 174, the rear end of a leaf spring 178 extending in the direction opposite to the direction of arrow A is
52. A resin standby roller 180 that is hard to deform is rotatably fixed to the distal end of the leaf spring 178. As described later, the leaf spring 178 is pushed down according to the rotational position of the pulley 174, and the standby roller 18
0 comes into contact with the roll paper 14a and the paper feed roller 76 separates from the roll paper 14a.

A rotation shaft 182 extends slightly parallel to the rotation shaft 166 in the direction of arrow A from the rotation shaft 166. Both ends of the rotating shaft 182 are
Is rotatably fixed to a fixing plate 184 formed in the above. A gear 184 is fixed to a portion of the rotating shaft 182 facing the electromagnetic clutch 162. Electromagnetic clutch 1
A transmission belt 186 that transmits the rotational force of the drive motor 156 is stretched between the gear 62 and the gear 184. The paper feed rollers 76 are fixed to portions of the rotary shaft 182 slightly inside from both ends. Here, two electromagnetic clutches 162, 164, a rotating shaft 166, a leaf spring 17
A standby member according to the present invention is configured by the standby roller 8 and the standby roller 180.

Referring to FIG. 2, the movement of the standby roller 180 and the paper feed roller 76 will be described. In this figure, FIG.
Are denoted by the same reference numerals.

The paper feed roller 76 is selectively moved to either a paper feed position in contact with the outer peripheral surface of the roll paper 14a or a standby position distant from the outer peripheral surface in accordance with the movement of the standby roller 180. Located in. While the roll paper 14a is being fed (during image formation and printing), the pulley 174 is separated from the leaf spring 178 and the paper feed roller 76 is pressed against the surface of the roll paper 14a as shown in FIG. are doing. In this state, the electromagnetic clutch 162 is connected and the electromagnetic clutch 164 is disconnected.

After the paper feeding (image formation) is completed, the electromagnetic clutch 162 is disconnected and the electromagnetic clutch 164 is connected under the control of a controller (not shown). In this state, the drive motor 156 rotates so as to rotate the pulley 174 by 45 ° in the direction of arrow B. As a result,
As shown in (b), the long diameter portion 174a of the pulley 174 pushes down the leaf spring 178. Thereby, the standby roller 1
80 moves downward to come into contact with the outer peripheral surface of the roll paper 14a, and the upper paper supply plate 152 floats up by the distance that the standby roller 180 is lowered, so that the paper supply roller 76 separates from the outer peripheral surface of the roll paper 14a.

As described above, when the roll paper 14a is not used, the standby roller 180 is brought into contact with the outer peripheral surface of the roll paper 14a, and the paper feed roller 76 is separated from the outer peripheral surface of the roll paper 14a. Even if it is not used, the paper feed roller 76 is
Can be suppressed from being deformed due to the contact with the roll paper 14a or the paper feed roller 76. Standby roller 1
Since 80 is cylindrical, it is not easily deformed. Further, since the length of the standby roller 180 is longer than the length of the paper feed roller 76, the standby roller 180
The standby roller 180 contacts the outer peripheral surface of the roll paper 14a with a contact area larger than the contact area when the contact is made. For this reason, deformation is less likely to occur on the outer peripheral surface of the roll paper 14a.

When shifting from the standby state (state (c)) to the printing state (state (d)), the drive motor 1
56 rotates so as to rotate the pulley 174 by 45 ° in the direction of arrow B. As a result, as shown in (d),
The major diameter portion 174 a of the pulley 174 is separated from the leaf spring 178. As a result, the standby roller 180 moves upward and separates from the outer peripheral surface of the roll paper 14a, and the upper paper supply plate 152 moves downward by the distance that the standby roller 180 has risen, so that the paper supply roller 76 moves to the outer peripheral surface of the roll paper 14a. Make pressure contact. As a result, the roll paper 14a can be fed.

[0049]

As described above, according to the image forming apparatus of the present invention, when the roll-shaped recording medium is not used, the paper feed roller can be positioned at the standby position by the standby member. Away from the outer peripheral surface of the recording medium. Therefore, even when the image forming apparatus is not used for a long period of time, the roll-shaped recording medium and the paper feed roller are not easily deformed due to the paper feed roller coming into contact with the roll-shaped recording medium.

In the case where the standby member has a cylindrical standby roller that comes into contact with the outer peripheral surface of the roll-shaped recording medium when the paper feed roller is at the standby position, the standby roller Is difficult to deform because it is cylindrical.
For this reason, even if the image forming apparatus is left unused for a long time, the roll-shaped recording medium and the paper feed roller are less likely to be deformed.

When the standby roller is longer than the length of the paper feed roller, the standby roller has a contact area larger than a contact area when the paper feed roller comes into contact with the outer peripheral surface of the roll-shaped recording medium. Contacts the outer peripheral surface of the roll-shaped recording medium. For this reason, deformation is less likely to occur on the outer peripheral surface of the roll-shaped recording medium.

Further, when the standby roller is made of resin, the standby roller is less likely to be deformed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an upper paper feed unit to which a standby member is attached.

FIG. 2 is an explanatory diagram illustrating the movement of a standby roller.

FIG. 3 is a side view schematically showing a conventional plotter.

FIG. 4 is a side view schematically showing a plotter obtained by improving the plotter shown in FIG. 3;

FIG. 5 is a side view schematically showing a type of plotter in which two roll-shaped recording media can be set at the same time.

FIG. 6 is a schematic diagram illustrating an example of a plotter capable of eliminating slack in a roll-shaped recording medium.

[Explanation of symbols]

 76 paper feed roller 152 upper paper feed plate 156 drive motor 162,164 electromagnetic clutch 166 rotating shaft 174 pulley 178 leaf spring 180 standby roller

Claims (4)

[Claims] An image for forming an image by selectively feeding either a roll-shaped recording medium wound in a roll shape or a cut sheet cut to a predetermined size to a predetermined image forming area. In the forming apparatus, an insertion opening, into which the roll-shaped recording medium and the cut sheet are inserted, leading to the image forming area, and the roll, which comes into contact with the outer peripheral surface of the roll-shaped recording medium disposed at a position away from the insertion opening, Paper feed roller that feeds into the insertion slot while pulling out the recording medium, and a paper feeding position that contacts the outer peripheral surface of the roll-shaped recording medium and a standby position that is separated from the outer peripheral surface. An image forming apparatus, comprising: a standby member for positioning the paper feed roller. 2. The apparatus according to claim 1, wherein the standby member includes a cylindrical standby roller that comes into contact with an outer peripheral surface of the roll-shaped recording medium when the paper feed roller is at the standby position. Item 2. The image forming apparatus according to Item 1. 3. The image forming apparatus according to claim 2, wherein the standby roller is longer than a length of the paper feed roller. 4. The image forming apparatus according to claim 2, wherein the standby roller is made of resin.