JP2000264512A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device unlikely to run askew when a roll-form recording medium is being transported. SOLUTION: A sheet feed roller 76 to feed a sheet of roll paper 14a into a plotter 50 is arranged near the forefront of an upper sheet feeding unit 70. Part of the feed roller 76 ranges out of a guide plate 78, and if the unit 70 is lowered, the ranging-out part is contacted by pressure to the peripheral surface of the roll paper 14a. The feed roller 76 rotates not only in such a way as drawing out the roll paper leading edge in the direction of arrow A (positive rotation) but also in the opposite direction (reverse rotation) so that the roll paper 14a is rewound. A lower sheet feeding unit 110 is of similar structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for forming an image on a recording medium.

[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. Among these image forming apparatuses, there are a recording medium of a type that can selectively use both a cut sheet cut into a predetermined size in advance 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.

With reference to FIGS. 9 to 11, 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. 9 is a side view schematically showing a conventional plotter, and FIG. 10 is a side view schematically showing a plotter obtained by improving the plotter shown in FIG. FIG. 11 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. 9, in a plotter 10, a roll paper 14 (an example of a roll-shaped recording medium) is generally disposed slightly below an image forming area 12 where an image is formed on a recording medium. Have been. Tip 1 of roll paper 14
4 'is pulled out, inserted into the roll paper insertion slot 16, and sent to the transport roller 18. Thereafter, while moving the carriage 22 on which the print head 20 is mounted in the scanning direction (perpendicular to the plane of FIG. 9), ink is ejected onto a 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 roll sheet insertion port 16 and is sent to the transport roller 18. In this case, in order to feed the cut sheet 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, a user (operator) manually feeds the leading end 14 ′ of the roll paper 14 to the transport roller 18. As a result, instead of the cut paper 24, the roll paper 14
The preparation for forming an image 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.

In order to enable the above-mentioned remote control, a plotter 30 of the type shown in FIG. 10 has been proposed. In this plotter 30, a pair of feed rollers 32a,
The roll paper 14 is conveyed while being pinched by 32b, and is sent to the conveyance roller 18. Then, the feed rollers 32a, 32
2b and the transport roller 18 are both rotated (forward rotation), and the roll paper 14 is transported to the image forming area 12 to form an image. When forming an image on the cut sheet 24, the plotter 3
0, a cut sheet mode signal is sent to a controller (not shown) to rotate both the feed rollers 32a and 32b and the transport roller 18 in the reverse direction, so that the leading end 14 'of the roll paper 14 obstructs the path of the cut paper 24. The roll paper 14 is rewound to a position where the roll paper 14 is not to be moved to a standby state in which the leading ends 14 'of the roll paper 14 are held between the feed rollers 32a and 32b.

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.
Roll papers 14 can be set at the same time. In such a type of plotter 40, the feed rollers 32a, 3
By arranging 2b for each roll paper 14,
Any one of the two 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 remarkable 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.

By the way, in a plotter of the type shown in FIGS. 10 and 11, the roll paper 1 is attached to the feed rollers 32a and 32b.
When the roll paper 14 is conveyed while being conveyed to the conveyance roller 18 while nipping the leading end 14 ′ of the roll paper 14, the roll paper 14 may not be conveyed straight but may be conveyed obliquely and skew. 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.

By the way, in the plotter 10 shown in FIG.
The fed (pulled out) roll paper 14 is further transported by transport rollers 18 to be checked for skew by a detection sensor (not shown) fixed to the carriage 22. For example, A0 size width (840m
In the case of the roll paper m), the roll paper is fed out by about 600 mm in order to check for the presence of skew, the amount of deviation of the roll paper side end is detected, and it is determined whether the skew is within an 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]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus which is unlikely to skew when a roll-shaped recording medium is being conveyed.

[0022]

In order to achieve the above object, an image forming apparatus according to the present invention pulls out a roll-shaped recording medium wound in a roll form from one end, feeds it while rotating, and feeds the rolled recording medium. In an image forming apparatus that forms an image in a predetermined image forming area on a drawn-out portion, (1) rotating while press-contacting the outer peripheral surface of a roll portion of a roll-shaped recording medium that is still wound in a roll shape An image forming apparatus comprising a paper feed roller for feeding the rolled recording medium.

Here, (2) the paper feed roller may rotate in the direction opposite to the direction in which the roll-shaped recording medium is pulled out.

(3) The paper feed roller may be a roller that comes into pressure contact with the outer peripheral surfaces of both ends in the width direction of the roll portion.

Further, the image forming apparatus according to the present invention provides (4)
The paper feed roller may be provided with a contact / separation means for contacting / separating from the outer peripheral surface of the roll portion.

Furthermore, (5) the contact / separation means is rotated by an angle within a predetermined range around a rotation axis extending in parallel with the width direction of the roll portion, and is opposite to the rotation axis. May be a holding member for holding the paper feed roller.

Furthermore, the image forming apparatus of the present invention
(6) A detection means for detecting a recording medium may be provided near the holding member.

Furthermore, the image forming apparatus of the present invention
(7) There may be provided a remaining amount detecting means for detecting the remaining amount of the roll portion based on the position of the holding member.

(8) The paper feed roller may press the outer peripheral surface of the roll portion toward a rotation center axis when the roll portion rotates.

Furthermore, the image forming apparatus of the present invention
(9) There may be provided pressing means for pressing the rotation center axis of the roll portion so as to delay the rotation of the roll portion.

Furthermore, the image forming apparatus of the present invention
(10) A stop member may be provided for pushing the roll portion in parallel with the rotation center axis to position the roll portion at a predetermined reference position.

(11) The image forming apparatus according to the present invention, wherein the first conveying roller for conveying the drawn portion to the predetermined image forming area, or the predetermined image forming area of the roll-shaped recording medium. (12) between the paper feed roller and the transport roller, a transport roller for transporting the drawer portion is disposed between the paper feed roller and the transport roller. You do not have to.

Further, the image forming apparatus of the present invention
(13) A conveyance path formed between the sheet feeding roller and the conveyance roller, through which the drawing section passes, and (14) a resistance of the drawing section, passing through the conveyance path, received from the conveyance path is reduced. A resistance reducing member may be provided.

Furthermore, (15) the resistance reducing member may be a rotating body that rotates when it comes into contact with the recording medium.

Further, (16) the resistance reducing member may be arranged near the rotation axis of the holding member.

[0036]

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

First, a schematic structure of a plotter which is an embodiment of the image forming apparatus of the present invention will be described with reference to FIGS.

FIG. 1 is a cross-sectional view showing a plotter cut in the transport direction of roll paper. FIG. 2 is a perspective view showing a mounting portion to which a roll-shaped recording medium is mounted, and FIG.
FIG. 4 is a plan view showing a roll-shaped recording medium before being mounted on a mounting section of FIG. In these figures, the same components as those shown in FIGS. 9 to 11 are denoted by the same reference numerals.

As shown in FIG. 1, the plotter 50 is of a type in which two roll papers 14a and 14b can be loaded simultaneously. As shown in FIG. 3, a roll receiver 64 for fixing the roll paper 14a is fixed near one end of a roll shaft 62 that passes through the center of the roll paper 14a. The roll receiver 64 is formed with a collar 64a having an outer diameter longer than the outer diameter of the roll paper 14a.
The collar 64a comes into contact with and contacts the end of the roll paper 14a.

In mounting the roll paper 14a on the plotter 50, first, the roll paper 14a is inserted from the right side of the roll shaft 62 (the right side of the paper surface in FIG. 3), and the roll paper 14a is abutted against the collar 64a. Next, another roll receiver 66 is inserted into the roll shaft 62 from the right side and the roll paper 1 is inserted.
4a is fixed. The roll paper 14b has the same structure.

The roll paper 14a in this state is placed on the plotter 50.
1, the upper paper feed unit 70 is pivoted upward and opened. Thereby, the cover 72
Is fixed to the magnet receiving plate 52 fixed to the main body of the plotter 50, and the upper sheet feeding unit 7
0 remains open and the roll paper 14a is
It can be attached to.

When the roll paper 14a is mounted on the plotter 50, both ends of the roll shaft 62 are rotatably held by roll holding members 54 and 56, as shown in FIG. The springs 54 for pressing the roll shaft 62 toward the center of rotation of the roll holding members 54 and 56, respectively.
a, 56a (an example of a pressing means according to the present invention) are fixed. These springs 54a, 56a
2 becomes a resistance when rotating, and springs 54a, 56a
, The rotation of the roll shaft 64 is delayed as compared with the case where there is not. . A spring 56b (an example of a stop member according to the present invention) is disposed adjacent to the spring 56a.
The roll shaft 62 is pressed in its longitudinal direction. This allows
The roll paper 14a is moved to the left side of the paper surface of FIG. 2, and this position becomes the reference position of the roll paper 14a. Therefore, the roll paper 14a is pulled out from one end while rotating at this reference position.

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. A detection sensor (an example of a detection unit according to the present invention, not shown) for detecting the roll paper 14a is disposed near the rotation shaft 82. When the detection sensor detects the roll paper 14a, a paper feed signal is transmitted to a controller (not shown). For example, after three seconds, the paper feed roller 76 starts rotating, and 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.

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. The flapper 88
The rib of the flapper 88 may be partially extended without forming an arm at the end of the flapper.

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 detecting sensor 96 (when the pull-out portion is not loose), the transport amount by the paper feed roller 76 is increased. The rotation of the paper roller 76 is stopped to interrupt the paper feeding.

The case where the above-mentioned skew exceeds a predetermined value will be described.

In this case, as described above, the roll paper 1
The conveyance of 4a is stopped, and a warning to the user is displayed on the display panel of the plotter 50. In accordance with this display, the operator (user) tilts the pressure lever 98 in the direction of arrow B to raise the pressure roller 100. Next, hold the left and right ends of the drawn portion and pull lightly toward the front to apply tension, and then return the pressure lever 98 to its original position. A sensor 9 for detecting the pressurized state by the pressurizing roller 100 is provided near the center of rotation of the pressurizing lever 98.
8a is installed. After the pressure is detected by the sensor 98a, the carriage 22 is moved to detect the end of the drawn portion, and the drawn portion is retracted. The skew amount of the drawn portion is measured in a state where the drawn portion is retracted, and if the skew amount is equal to or smaller than a predetermined value, the leading end (paper leading end) of the drawn portion is returned once until the detection sensor 94 detects it. The sheet is advanced by a predetermined amount to cut the leading edge of the sheet. The subsequent movement of the sheet is the same as the case where the skew amount is equal to or less than the predetermined value. The leading edge of the paper is automatically cut only when the roll paper 14a is mounted on the plotter 50.

Next, the roll paper 14 is placed below the plotter 50.
The case in which b is mounted and transported will be described.

In this case, first, the lower roll mode in which the roll paper 14b is mounted on the lower tier of the plotter 50 is set by the operation unit (not shown). If the upper roll mode has been set before this setting, the transport roller 18 and the paper feed roller 76 are rotated in the reverse direction, the roll paper 14a is rewound, and the drawn portion (paper) is retracted. As a result, the leading end of the drawn-out portion of the roll paper 14a passes through the flapper 88, and after the detection sensor 20 detects the leading end of the drawn-out portion, the drawn-out portion is stopped and waits at that position.

The lower roll paper 14b is the lower paper feed unit 1
10 and is fed. Roll paper 14b
Is pulled out by the lower sheet feeding unit 110, the detection sensor 94 detects that there is no sheet in the conveyance path through which the drawn-out portion is conveyed, and the pressing lever 98 is moved to the normal position (in the conveyance-possible state). Position). When the above detection and confirmation are performed, the paper feed roller 112 operates, and when the detection and confirmation are not performed, the paper supply roller 112 does not operate.

The procedure for mounting the lower roll paper 14b on the main body of the plotter 50 is the same as the procedure for mounting the upper roll paper 14a on the main body of the plotter 50. Roll paper 14
When the leading end of the roll paper 14b is inserted into the main body of the plotter 50, a tension is applied between the rolled portion of the roll paper 14b and the leading end of the drawn-out portion. If the roll is pressed against the roll, the drawer can be moved straight without skewing. When the lower roll paper 14b is attached to the main body of the plotter 50, as shown in FIG.
The end of the roll paper 4b abuts, and the roll paper 14b is reliably located at the reference position. For this reason, when the roll paper 14b is pulled out from one end, the straightness of the drawn-out portion is increased and skew is less likely to occur. When the operator sets the cut paper mode, the upper roll paper 14
Similarly to the case a, the lower roll paper 14b also retracts to the standby position. In addition, a weight 1 is provided near the paper feed roller 112.
14 is fixed, and presses the roll paper 14b more strongly. The weight 114 is not always necessary, and the weight 114 depends on the pressing force due to the weight of the lower sheet feeding unit 110.
Determine the weight of Further, the magnet 118 fixed to the cover 116 is attracted to the magnet receiving plate 119 fixed to the main body of the plotter 50, the lower paper feed unit 110 is kept open, and the roll paper 14b can be mounted on the plotter 50. Become.

Next, referring to FIG.
A drive system for driving the paper feed roller 76 fixed to 0 will be described.

FIG. 4 is a perspective view showing the upper paper feeding unit 70. In this figure, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

A motor 122 is fixed outside the left side plate 120 of the main body of the plotter 50. Pulleys 124a and 124b are fixed to a rotation shaft 122a of the motor 122. An electromagnetic clutch 126 is fixed at a position slightly away from the motor 122. This electromagnetic clutch 126
Is provided with a pulley 124c. A timing belt 27 is stretched between the pulleys 124c and 124b. The rotating shaft 8 is attached to the pulley 124c.
2 is passed.

The rotation shaft 82 is connected to the left side plate 120 and the right side plate 13.
0 are rotatably held by bearings 132 fixed to each. The guide plate 7 is connected to the rotating shaft 82 via a bearing 134.
8 is held so as to rotate. A plurality of freely protruding rollers 136 (three in FIG. 4 are shown) are attached to the rotating shaft 82 by a retaining ring 138. A gear 140 is fixed to the center of the rotating shaft 82.

A short shaft 144 extending parallel to the rotation shaft 82 is disposed in a portion of the guide plate 78 near the gear 140. Receiving plates 146, 148 are fixed to the guide plate 78, and bearings 150 are attached to the receiving plates 146, 148, respectively. The shaft 144 includes a bearing 150
Are rotatably held on the receiving plates 146 and 148 via. A gear 142 meshing with the gear 140 is rotatably fixed to the shaft 144.

The gear 142 is made of resin, and is integrally formed with the teeth that mesh with the timing belt 152.
At the other end of the timing belt 152, a gear 154 having teeth engaging with the timing belt 152 is disposed. The gear 154 is rotatably fixed to a shaft 156. The receiving plates 158 and 160 that hold the shaft 156 via the bearing 156 hold the upper paper feed roller shaft 164 via the bearing 162. Upper feed roller shaft 1
A gear 166 meshing with the gear 154 is fixed to 64. Further, a paper feed roller 76 is fixed to both ends in the longitudinal direction of the upper paper feed roller shaft 164.

The drive system for driving the paper feed roller 112 fixed to the lower paper feed unit 110 (see FIG. 1) is almost the same. The lower paper feed unit 110 has a structure in which the drive is transmitted by a configuration similar to that of the upper paper feed unit 70 via a timing belt 168 wrapped around the motor 122. By controlling the electromagnetic clutch 126 and an electromagnetic clutch (not shown) fixed to the shaft 170 (see FIG. 1), the upper paper feed unit 70 and the lower paper feed unit 11 are controlled.
0 is configured to transmit the drive to the paper feed rollers 76 and 112 disposed respectively. An example of the contacting / separating means according to the present invention includes the upper paper feeding unit 70 and the lower paper feeding unit 11.
Electromagnetic clutch 126 and guide plate 78 for rotating
And various other components. An example of the holding member according to the present invention includes the upper paper feed roller shaft 164.

An example of the remaining amount detecting means according to the present invention will be described with reference to FIGS.

FIG. 5 is a side view showing the vicinity of the rotation shaft of the upper paper feed unit, and FIG. 6 is an explanatory diagram showing the relationship between the remaining amount of roll paper and the detection signal.

As shown in FIG. 4, receiving plates 170 and 172 are fixed to the guide plate 78 by spot welding. The rotating shaft 82 is held on the receiving plates 170 and 172 via a bearing 134. A portion of the receiving plate 172 is extended to form an extended portion 172a, and a hole 172b is opened in a portion of the extended portion 172a. The extended portion 172a blocks the optical paths of the two detection sensors 174a and 174b (photo interrupters) in accordance with the amount of rotation of the rotation shaft 82. In addition, the above-mentioned hole 172
Depending on the position of b, the optical paths of the detection sensors 174a and 174b are not interrupted. One example of the remaining amount detecting means according to the present invention includes the detection sensors 174a and 174b and the extension portion 172a.
It is composed of

The amount of rotation of the rotation shaft 82 corresponds to the angle of inclination of the guide plate 78, and the angle of inclination corresponds to the remaining amount of the roll paper 14a. When the remaining amount of the roll paper 14a is large (almost unused), the inclination angle of the guide plate 78 is large,
The extension 172a of the receiving plate 172 has two detection sensors 1
The optical paths of both 74a and 174b are blocked. In this case, 2
As shown in FIG. 6, a signal of (0, 0) is transmitted to a controller or the like from both of the detection sensors 174a and 174b.
It is determined that the upper paper feed unit 70 is open.

When the roll paper 14a has been used but still has a sufficient amount, the inclination angle of the guide plate 78 becomes slightly small, and the optical path of the detection sensor 174a is cut off. 172b is located and is not blocked. For this reason, as shown in FIG. 6, the signal of (0, 1) is transmitted to a controller or the like, and it is determined that there is still a sufficient remaining amount.

When the remaining amount of the roll paper 14a is reduced to about one fourth, the inclination angle of the guide plate 78 becomes considerably small, and the hole 172b is located in the optical path of both the two detection sensors 174a and 174b. Therefore, these optical paths are not blocked.
Therefore, as shown in FIG. 6, the signal (1, 1) is transmitted to the controller or the like, and it is determined that the remaining amount of the roll paper 14a is reduced to about one fourth.

When the roll paper 14a is not set (when the roll paper 14a is completely used),
The inclination angle of the guide plate 78 becomes very small, and the optical path of the detection sensor 174b is blocked, but the hole 172b is located in the optical path of the detection sensor 174a and is not blocked. For this reason,
As shown in FIG. 6, a signal (1, 0) is transmitted to a controller or the like, and it is determined that the roll paper 14a is not set.

When an image is formed on the surface of a large-format (large-size) recording medium by intermittent feeding by the ink-jet method as in the plotter 50 of the present embodiment, the landing accuracy of the ejected ink dots depends on the formation accuracy. Greatly affects the image quality. One of the factors for improving and stabilizing the intermittent feeding accuracy is a force (grip force) by which a transport roller that transports a recording medium while nipping the recording medium grips the recording medium. In order to reduce the fluctuation of the grip force during the conveyance, it is preferable that the resistance of the component that comes into contact with the recording medium during the conveyance is as small as possible. In particular, in the case of an image forming apparatus such as the plotter 50, which can selectively use a plurality of recording media, the recording medium is conveyed while being curved, so that the conveyance path is curved. Therefore,
A tension acts on the recording medium being conveyed, and in this case, the recording medium being conveyed always contacts a guide member or the like that forms the conveyance path.

Therefore, as shown in FIG. 1, the plotter 50 moves the roll paper 14a out of the transport path of the roll paper 14a.
The projection roller 136 is provided at a portion where the sheet a is conveyed while being curved.
(An example of the resistance reducing member according to the present invention.) The protruding roller 136 protrudes into the transport path,
It rotates with very weak force. For this reason, the projecting roller 13
Roll paper 1 being transported along the transport path where 6 protrudes
When the protrusion roller 136 comes into contact with 4a, it rotates. As a result, the resistance that the roll paper 14a receives from the transport path is reduced, and the load on the transport roller 18 is also reduced. Therefore, the feeding accuracy when the roll paper 14a is transported can be kept very good. In addition, the projecting roller 136
Is attached to the rotation shaft 82 when the guide plate 78 rotates, so that there is an advantage that the structure is simplified without requiring an extra member.

Here, what is considered as one of the causes of the skew will be discussed.

When the roll paper 14a is transported, the transport roller 18 (see FIG. 1) that transports the roll paper 14a to the image forming area 12 (see FIG. 1), and the roll paper that is transported by the transport roller 18 When the roll paper 14a is kept parallel, the drawn portion of the roll paper 14a drawn by the paper feed roller 76 hardly skews. However, when another transport roller that transports the sheet while nipping the drawn portion is disposed between the sheet feeding roller 76 and the transport roller 18, the parallelism between the other transport roller and the drawn portion is oblique. It is important in preventing lines. In order to prevent the drawer from skewing, it is necessary to keep the other transport roller and the drawer parallel as described above, and extremely strict control is required for assembling the plotter 50 and the like. So, plotter 5
0, the distance between the paper feed roller 76 and the transport roller 18 is
The transport roller that transports while holding the drawer is not provided. Thereby, the skew of the drawer portion is further reduced.

Referring to FIG. 7, members for switching from roll paper 14a to cut paper when forming an image on cut paper will be described.

FIG. 7 is a perspective view showing a guide plate provided with a flapper for switching from the roll paper transport path to the cut paper transport path.

A flapper 88 for switching from the roll paper 14a to the cut paper is provided on the downstream side of the upper paper supply unit 70 (see FIG. 1) in the transport direction of the roll paper 14a and on the upstream side of the transport roller 18. Guide plate 1 on which is arranged
80 are installed. The guide plate 180 transports the roll paper 14 a passing through the upper paper feed unit 70
To guide. The guide plate 180 extends in a direction orthogonal to the transport direction of the roll paper 14a, and both ends thereof are fixed to the left side plate 120 and the right side plate 130. Information board 180
, A pair of flapper receiving members 182 having an L-shaped cross section are fixed in three sets (three in FIG. 7) in the orthogonal direction.

A flapper shaft 184 extending in the above-described orthogonal direction is fixed to each set. 4 on each flapper shaft 184
Up to five flapper 88 are held swingably, and each flapper 88 is swung by a light force and pushed up. Of the plurality of flappers 88, a detection sensor 90 that detects the flapper 88 that has been swung up is provided slightly above the leftmost (reference side of the recording medium) flapper 88 in FIG.

The flapper 88 is formed in a rib shape from a resin. The lower end 88a of each flapper 88 is
Path (medium path) through opening 180a opened in
It protrudes under its own weight. For this reason, when the roll paper 14a passes below the guide plate 180, the flapper 88 is pushed up by the passing roll paper 14a, and the detection sensor 90
Operates. By this operation, a signal is transmitted from the detection sensor 90 to the controller, and the transport roller 18 is rotated at a predetermined timing.

As described above, when the roll paper 14a is in the standby state, the roll paper 14a disappears below the guide plate 180, and the flapper 88 falls down by its own weight. In addition, the flapper 88 is positioned in front of the main body of the plotter 50 (arrow C).
Direction) is not pushed up depending on the recording medium conveyed from the direction (1). Therefore, when a cut sheet is inserted from the front of the main body of the plotter 50, the flapper 88 guides the cut sheet, and the cut sheet is guided by a guide plate 186 (see FIG. 1) extending substantially parallel to the arrow C direction. Then, the sheet advances to the rear of the main body of the plotter 50 without entering the transport path of the roll paper 14a.

Referring to FIG. 8, a member for switching from the roll paper 14b to the cut sheet when forming an image on the cut sheet will be described.

FIG. 8 is a perspective view showing a guide plate provided with a flapper for switching from a roll paper transport path to a cut paper transport path.

A flapper for switching from the roll paper 14b to the cut paper is located downstream of the lower paper feed unit 110 (see FIG. 1) in the transport direction of the roll paper 14b and upstream of the transport roller 18. Guide plate 19 arranged
0 is formed. The guide plate 190 transports the roll paper 14 b passing through the lower paper feed unit 110 to the transport roller 18.
To guide. The guide plate 190 extends in a direction perpendicular to the direction of transport of the roll paper 14b, and both ends thereof are fixed to the left side plate 120 and the right side plate 130. Information board 19
A plurality of L-shaped holding plates 192 are fixed to 0 (three in FIG. 8) in the orthogonal direction. A shaft 194 is fixed between the plurality of holding plates 192. Axis 19
4 holds a plurality of swing plates 196 that swing about the shaft 194 as a central axis.

A flapper 198 is rotatably held by the two swinging plates 196 facing each other. Flapper 1
Reference numeral 98 denotes resin molded such that a plurality of thin disks are arranged at intervals. The plurality of thin disks enter into a skewer-shaped slit formed in the platen 92 (see FIG. 1) in a non-contact state. End 196 of rocking plate 196
a, a tension spring 200 is hung on the end 196a.
The end 196b on the opposite side is urged to rotate about the shaft 194 in the direction of arrow D (substantially upward).

Accordingly, although the flapper 198 is urged upward, the flapper 198 is disposed at a predetermined position because the swinging plate 196 abuts against the platen 92. A detection sensor 202 that detects the position of the flapper 198 is disposed on the reference side (the left side in FIG. 8) in the width direction of the roll paper 14b. For this reason, the roll paper 14
When b passes through the guide plate 204 (see FIG. 1), the flapper 198 is pushed down by the passing roll paper 14b, and the detection sensor 202 operates. By this operation, a signal is transmitted from the detection sensor 202 to the controller, and the conveyance roller 1
8 is rotated at a predetermined timing.

As described above, when the roll paper 14b enters the standby state, the roll paper 14b retreats, and the flapper 198 rises. The flapper 198 is connected to the plotter 5.
It cannot be pushed down by the recording medium conveyed from the front of the main body of the No. 0 (in the direction of arrow C). Therefore, when a cut sheet is inserted from the front of the main body of the plotter 50, the flapper 198 guides the cut sheet toward the guide plate 186, and the cut sheet is guided by the guide plate 186 to convey the roll paper 14b. The user proceeds to the rear of the main body of the plotter 50 without entering the road.

When the upper roll paper 14a is pulled out and fed, the light weight of the flapper 88 acts on the portion where the paper is fed. On the other hand, the lower roll paper 14
When tension acts between b and the pair of transport rollers 18,
The weight of the roll paper 14b acts on the flapper 198, and the flapper 198 is pressed downward.
4b only makes light contact with the guide plate 204. However, when the downward force is large, the roll paper 14b comes into strong contact with the guide plate 204, and the transport roller 18
This has a bad effect on the gripping force (clamping force) for pinching. Therefore, when a downward force acts on the flapper 198 from the roll paper 14b, the swinging plate 196 is stopped by the stopper 206 so as not to drop below the predetermined position. For this reason, the flapper 198 is made to protrude into the transport path so that the flapper 198 rotates even with a small force. As a result, even if tension is applied to the roll paper 14b being transported, the transport rollers 1b
8 has less influence on the gripping force and can be stably transported.

[0087]

As described above, according to the image forming apparatus of the present invention, since the paper feed roller rotates while being in pressure contact with the outer peripheral surface of the roll portion, the pulled-out portion is unlikely to be inclined, so The portion that is pulled out and fed is hard to skew.

Here, when the paper feed roller rotates in the direction opposite to the direction in which the roll-shaped recording medium is pulled out, when the drawn-out portion of the roll-shaped recording medium is loosened, By rotating the paper feed roller in the opposite direction (reverse rotation) to rewind the roll-shaped recording medium, slack in the drawn-out portion can be eliminated.

In the case where the paper feed roller comes into pressure contact with the outer peripheral surfaces of both ends in the width direction of the roll portion, both ends in the width direction of the roll portion are pressed. However, it becomes more difficult to incline, and the skew can be reduced more reliably.

Further, in the case where the image forming apparatus of the present invention is provided with contact / separation means for bringing the paper feed roller into contact with / separating from the outer peripheral surface of the roll portion, if the paper feed roller is skewed, the paper feed roller is fed Since the roller can be separated from the roll portion, the skew can be easily corrected.

Further, the contact / separation means is provided at a portion opposite to the rotation axis, which rotates by an angle within a predetermined range around a rotation axis extending parallel to the width direction of the roll portion. In the case of a holding member for holding the paper feed roller, it is possible to form a contact / separation unit having a simple configuration.

Further, in the case where the image forming apparatus of the present invention is provided with detecting means for detecting the recording medium disposed near the holding member, when the drawer is inserted close to the holding member, Since the drawer is detected by the detecting means, it is possible to know the timing to start rotating the paper feed roller.

Further, when the image forming apparatus of the present invention includes a remaining amount detecting means for detecting the remaining amount of the roll portion based on the position of the holding member, the remaining amount of the roll-shaped recording medium is detected. Therefore, an easy-to-use image forming apparatus can be obtained.

Further, when the paper feed roller presses the outer peripheral surface of the roll portion toward the rotation center axis when the roll portion rotates, the paper feed roller further strengthens the roll portion. Since the pressure can be applied, the portion of the roll-shaped recording medium that is pulled out and fed is more difficult to skew.

Further, when the image forming apparatus of the present invention is provided with pressing means for pressing down the rotation center axis of the roll portion so as to delay the rotation of the roll portion, the roll portion and the drawn-out portion may be provided. Since tension is applied during this period, and this portion is pulled, slackening of this portion can be reduced.

Further, when the image forming apparatus of the present invention is provided with a stop member for pushing the roll portion in parallel with the rotation center axis and positioning the roll portion at a predetermined reference position, the roll portion is always kept at a predetermined reference position. Since the roll portion can be positioned at this reference position, the drawn portion can be harder to skew by rotating the roll portion at this reference position.

Further, the image forming apparatus of the present invention has passed the first conveying roller for conveying the drawn-out portion to the predetermined image forming area, or has passed the predetermined image forming area of the roll-shaped recording medium. A second conveying roller for pulling the portion to further convey it, and further comprising a conveying roller for conveying the drawer portion between the paper feeding roller and the conveying roller. Since there is nothing between the paper feed roller and the transport roller to pinch the drawn portion, the skew of the recording medium is further reduced.

Further, the image forming apparatus of the present invention may further comprise a conveying path formed between the feed roller and the conveying roller, through which the drawing section passes, and a drawing section passing through the conveying path. When a resistance reducing member for reducing the resistance received from the conveyance path is provided, the resistance at the time of conveyance is reduced, so that the recording medium is not easily biased due to this resistance, and the recording medium being conveyed further skews. Hateful.

Further, in the case where the resistance reducing member is a rotating body that rotates by contacting a recording medium,
A resistance reducing member having a simple configuration can be obtained.

Further, when the resistance reducing member is disposed near the rotation axis of the holding member, the recording medium is likely to be bent near the rotation axis, but the resistance reducing member is not easily bent. Since they are arranged, it is possible to prevent skewing and paper jam of the recording medium due to resistance at the time of bending.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a plotter cut in a transport direction of roll paper.

FIG. 2 is a perspective view showing a mounting portion on which a roll-shaped recording medium is mounted.

FIG. 3 is a plan view showing a roll-shaped recording medium before being mounted on a mounting section in FIG. 2;

FIG. 4 is a perspective view showing an upper sheet feeding unit.

FIG. 5 is a side view showing the vicinity of a rotation shaft of the upper paper feeding unit.

FIG. 6 is an explanatory diagram showing a relationship between a remaining amount of roll paper and a detection signal.

FIG. 7 is a perspective view showing a guide plate provided with a flapper for switching from a roll paper transport path to a cut paper transport path.

FIG. 8 is a perspective view showing a guide plate provided with a flapper for switching from a roll paper transport path to a cut paper transport path.

FIG. 9 is a side view schematically showing a conventional plotter.

FIG. 10 is a side view schematically showing a plotter obtained by improving the plotter shown in FIG. 9;

FIG. 11 is a side view schematically showing a plotter of a type in which two roll-shaped recording media can be set at the same time.

[Explanation of symbols]

 14a, 14b Roll paper 18 Transport roller 50 Plotter 64 Roll receiver 64a Collar 70 Upper paper feed unit 54a, 56a, 56b Spring 76 Paper feed roller 78 Guide plate 82 Rotating shaft 84, 94 Detection sensor 88 Flapper 96 Looseness detection sensor 110 Below Paper feed unit 112 Paper feed roller 122 Motor 172 Receiving plate 172a Extension 172b Hole 174a, 174b Detection sensor

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Ryoma Suzuki Inventor 6-3-3 Shimorenjaku, Mitaka-shi, Tokyo F-term (reference) in Co., Ltd. 3F052 AA01 AB04 BA02 CA08 DA06 DA13 3F103 AA02 BA03 BA11 BA33 3F105 AA02 AB02 AB04 BA04 BA16 CA03 CA07 DA02 DB02 DB03 DB04

Claims (14)

[Claims] 1. An image forming apparatus which draws out a roll-shaped recording medium wound in a roll form from one end thereof, feeds it while rotating, and forms an image in a predetermined image forming area on the drawn-out portion. An image characterized by comprising a paper feed roller that feeds the roll-shaped recording medium by rotating while pressing and contacting the outer peripheral surface of a roll portion of the roll-shaped recording medium that is still wound in a roll shape Forming equipment. 2. The image forming apparatus according to claim 1, wherein the paper feed roller also rotates in a direction opposite to a direction in which the roll-shaped recording medium is pulled out. 3. The image forming apparatus according to claim 1, wherein the paper feed roller is configured to contact the outer peripheral surfaces of both ends in the width direction of the roll portion under pressure. 4. The image forming apparatus according to claim 1, further comprising a contacting / separating means for contacting / separating the paper feed roller from an outer peripheral surface of the roll portion. 5. The rotating device according to claim 1, wherein the contacting / separating means is rotated by an angle within a predetermined range around a rotation axis extending in parallel to a width direction of the roll portion. The image forming apparatus according to claim 4, wherein the image forming apparatus is a holding member that holds a sheet feeding roller. 6. The image forming apparatus according to claim 5, further comprising: a detecting unit disposed near the holding member for detecting a recording medium. 7. The image forming apparatus according to claim 5, further comprising a remaining amount detecting unit that detects a remaining amount of the roll portion based on a position of the holding member. 8. The paper feed roller according to claim 1, wherein the paper feed roller presses an outer peripheral surface of the roll portion toward a rotation center axis when the roll portion rotates. The image forming apparatus according to claim 1. 9. The apparatus according to claim 1, further comprising pressing means for pressing the rotation center axis of the roll portion so as to delay the rotation of the roll portion. Image forming apparatus. 10. The apparatus according to claim 1, further comprising a stop member that pushes the roll portion in parallel with the rotation center axis to position the roll portion at a predetermined reference position. Image forming device. 11. A first transport roller for transporting the drawn-out portion to the predetermined image forming area, or a second transport roller for pulling a portion of the roll-shaped recording medium that has passed through the predetermined image forming area and further transporting the portion. The image forming apparatus according to claim 1, further comprising any one of conveyance rollers, wherein no conveyance unit that conveys a drawn-out portion is disposed between the paper supply roller and the conveyance roller. The image forming apparatus according to claim 1. 12. A conveyance path formed between the paper feed roller and the conveyance roller, through which the drawing portion passes, and a resistance for reducing a resistance of the drawing portion passing through the conveyance path from the conveyance path. The image forming apparatus according to claim 11, further comprising a reduction member. 13. The image forming apparatus according to claim 12, wherein the resistance reducing member is a rotating body that rotates by contacting a recording medium. 14. The image forming apparatus according to claim 5, wherein the resistance reducing member is disposed near the rotation axis of the holding member. apparatus.