JP4072955B2 - Image forming apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that conveys a sheet using a conveyance belt.
[0002]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-53082
[Prior art]
As an image forming apparatus (or image recording apparatus) such as a printer, a facsimile machine, and a copying apparatus, for example, an ink jet recording apparatus is known. The ink jet recording apparatus is a sheet from an ink recording head (it is not limited to paper, but means that ink droplets including OHP can be attached, and is also called a recording medium, a recording medium, or recording paper). It is possible to record by discharging ink to high-definition image at high speed, low running cost, low noise, and color image using multi-color ink It has the advantage that it is easy.
[0004]
By the way, in the ink jet recording method, there is a phenomenon that when an image is formed, the paper is stretched by moisture contained in the ink in order to make the ink adhere to the paper. This phenomenon is called cockling. The cockling causes the paper to wave, and the position of the nozzle of the head and the surface of the paper changes from place to place. If the degree of cockling deteriorates, in the worst case, the paper will come into contact with the nozzle surface of the head, and the nozzle surface of the head may become dirty, or the paper itself may become dirty, resulting in a decrease in image quality. The impact position of the ink droplet may be shifted due to the influence.
[0005]
In the conventional ink jet recording apparatus, paper is fed by rollers, and two sets of rollers (one of which is a combination of a spur and a roller as described above) are arranged across a printing area. However, with this configuration, the sheet feeding accuracy can be guaranteed only when the sheet is engaged with the two sets of rollers.
[0006]
However, in recent years, since it is desired to increase the image printing area, it is impossible to guarantee the sheet feeding accuracy in order to secure the printing area, that is, one of the two pairs of rollers. However, there is also an ink jet recording apparatus that performs printing in a state where the paper is not bitten. However, in the state where the paper bites only one of the roller pairs, if the paper floats, it is impossible to cope with it, and because the paper conveyance force cannot be secured, the feeding accuracy cannot be guaranteed, so the image quality is also deteriorated. Problem arises.
[0007]
Therefore, as described in [Patent Document 1], in order to maintain the flatness of the paper, an endless charging belt is provided, and the surface of the charging belt is charged to electrostatically adsorb the paper. An ink jet recording apparatus has been proposed in which a sheet is conveyed by rotating a charging belt, thereby preventing the sheet from being lifted from the charging belt and maintaining high flatness.
[0008]
[Problems to be solved by the invention]
However, when the paper (recording medium) is transported electrostatically using a transport belt as in the conventional inkjet recording apparatus described above, the paper is separated from the transport belt by curvature separation. However, paper with weakness or paper that has become weak due to a solid image or the like does not undergo curvature separation and remains adsorbed to the conveyor belt, which causes a jam.
[0009]
In particular, in an image forming apparatus capable of duplex printing in which an image is formed on one side of a sheet and then an image is formed on the other side, it is difficult to separate the curvature of the sheet from the conveyance belt by forming the image on one side. However, there is a problem that it becomes difficult to feed the paper to the transport path for transporting the paper in order to form an image on the other side of the paper.
[0010]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of reliably separating a sheet from a conveyor belt for other side printing.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, an image forming apparatus according to the present invention includes a conveyance belt that sucks and conveys a recording medium, and the conveyance belt forms a conveyance direction for forming an image on one surface of the recording medium. An image forming apparatus that rotates in the reverse direction and feeds the recording medium to a reversing conveyance path that reverses the recording medium, and includes a separation claw that separates the recording medium from the conveyance belt and sends the recording medium to the reversing conveyance path . The portion for separating the recording medium is covered and held by an openable / closable opening / closing member .
[0012]
Here, minutes Hanaretsume can the configuration was disposed separably to the transport belt surface. Moreover, it can be set as the structure which provided the fall control member which controls the fall of a separation nail | claw . In this case, the fall restricting member may be a roller member , and the roller member may have a function of pressing the recording medium against the conveyance belt.
[0013]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the conveyance belt that sucks and conveys the recording medium is provided, and the conveyance belt has a conveyance direction for forming an image on one surface of the recording medium. An image forming apparatus that rotates in the reverse direction and feeds the recording medium to a reversing conveyance path that reverses the recording medium, and includes a separation claw that separates the recording medium from the conveyance belt and sends the recording medium to the reversing conveyance path . Since the recording medium is covered with a swingable opening / closing member that covers the part where the recording medium is separated, the recording medium can be reliably separated from the transport belt, and jams caused by poor separation, etc. Can be prevented, and more stable duplex printing becomes possible.
[0014]
In this ink jet recording apparatus, a carriage 3 is slidably held in a main scanning direction by a guide rod 1 and a stay 2 which are guide members horizontally mounted on left and right side plates (not shown), and a main scanning motor (not shown) is used in FIG. Move and scan in the direction of the arrow.
[0015]
The carriage 3 is provided with a recording head 4 composed of four ink jet heads that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk), and a plurality of ink ejection openings. They are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.
[0016]
As the ink jet head constituting the recording head 4, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like as an energy generating means for discharging ink can be used.
[0017]
The carriage 3 is also equipped with sub-tanks 5 for each color for supplying ink of each color to the recording head 4. Ink is supplied to the sub tank 5 from a main tank (ink cartridge) through an ink supply tube (not shown).
[0018]
On the other hand, as a paper feeding unit for feeding the paper 12 stacked on the paper stacking unit (pressure plate) 11 such as the paper feeding cassette 10, a half-moon roller (separately feeding the paper 12 one by one from the paper stacking unit 11) The sheet feeding roller 13 and the sheet feeding roller 13 are opposed to each other, and a separation pad 14 made of a material having a large friction coefficient is provided. The separation pad 14 is urged toward the sheet feeding roller 13 side.
[0019]
In order to convey the sheet 12 fed from the sheet feeding unit below the recording head 4, a conveying belt 21 for electrostatically attracting and conveying the sheet 12 and a guide 15 from the sheet feeding unit are provided. The counter roller 22 that also serves as a fall control member for transporting the paper 12 that is fed via the conveyor belt 21 and the paper 12 that is fed substantially vertically upward is changed in direction by approximately 90 ° and the conveyor belt 21. A guide member for copying up, a conveyance guide / separation claw 23 that also serves as a separation claw for separating the paper 12 from the conveyance belt 21 as will be described later, and a tip urged toward the conveyance belt 21 by the pressing member 24 And a pressure roller 25. In addition, a charging roller 26 as a charging unit for charging the surface of the transport belt 21 is provided.
[0020]
Here, the conveyance belt 21 is an endless belt, and is configured to be looped around the conveyance roller 27 and the tension roller 28 in the belt conveyance direction of FIG. This transport belt 21 is a surface layer that is a sheet adsorbing surface formed of a resin material having a pure thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon is performed using the same material as the surface layer. It has a back layer (medium resistance layer, ground layer).
[0021]
The charging roller 26 is disposed so as to contact the surface layer of the conveyor belt 21 and rotate following the rotation of the conveyor belt 21, and applies 2.5N to both ends of the shaft as a pressing force. The conveyance roller 27 also serves as the above-described earth roller, and is in contact with the middle resistance layer (back layer) of the conveyance belt 21 and is grounded.
[0022]
In addition, a guide member 31 is disposed on the back side of the conveyance belt 21 so as to correspond to a printing area by the recording head 4. Both ends of the guide member 31 in the main scanning direction are held between frame members 35 that hold the conveying roller 22, the tension roller 28, and the like.
[0023]
The upper surface of the guide member 31 protrudes closer to the recording head 4 than the tangent line of the two rollers (the conveyance roller 27 and the tension roller 28) that support the conveyance belt 21. Thereby, the conveyor belt 21 is pushed up and guided by the upper surface of the guide member 31 in the printing region.
[0024]
Further, a separation claw 41 serving as a separation mechanism for separating the paper 12 from the transport belt 21 is disposed in contact with the transport belt 21 as a paper discharge unit for discharging the paper 12 recorded by the recording head 4. A paper discharge roller 42 and a paper discharge roller 43 are arranged on the downstream side of the separation claw 41, and a paper discharge tray 44 for stocking the paper 12 to be discharged is further provided on the downstream side. Here, the separation claw 41 is supported by a support shaft so as to be swingable, and an elastic body such as a spring applies tension to the conveyor belt 21 side so as to contact the surface of the conveyor belt 21.
[0025]
A double-sided paper feeding unit 51 is detachably attached to the apparatus main body. The double-sided paper feeding unit 51 takes in the paper 12 returned by the reverse rotation of the transport belt 21, reverses it, and feeds it again between the counter roller 22 and the transport belt 21. At this time, the conveyance guide 23 also serves as a separation claw for separating the paper 12 from the conveyance belt 21 and feeding it into the duplex feeding unit 51.
[0026]
In the ink jet recording apparatus configured as described above, the paper 12 is separated and fed one by one from the paper feed unit, and the paper 12 fed substantially vertically upward is guided by the guide 15, and includes the transport belt 21 and the counter roller 22. The leading end is guided by the conveying guide 23 and pressed against the conveying belt 21 by the leading end pressing roller 25, and the conveying direction is changed by approximately 90 °.
[0027]
At this time, a positive output and a negative output are alternately repeated from the high voltage power source to the charging roller 26 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 21 is alternating, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 12 is fed onto the conveyance belt 21 charged alternately with plus and minus, the charge is polarized in the opposite direction to the charge pattern in the paper 12, so that a capacitor connected in parallel is formed. 12 is adsorbed by the conveyance belt 21, and the paper 12 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 21.
[0028]
Therefore, by driving the recording head 4 according to the image signal while moving the carriage 3, the ink droplets are ejected onto the stopped paper 12 to record one line, and after the paper 12 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 12 reaches the recording area, the recording operation is ended.
[0029]
At this time, in the case of single-sided printing, the paper 12 is discharged to the discharge tray 44. On the other hand, in the case of double-sided printing, the transported belt 21 is rotated in the reverse direction, and the recorded paper 12 is fed into the double-sided paper feeding unit 51 and reversed (the recording surface becomes the other surface). The paper is again sent onto the conveyor belt 21, and the recording is performed on the other surface of the paper 12 and discharged in the same manner as described above.
[0030]
Here, with reference to FIG. 3, a conveyance path and a separation mechanism in the recording apparatus will be described.
In this recording apparatus, as described above, during double-sided printing, the paper 12 is discharged below the recording head 4 in order to form an image on the paper 12 by rotating the conveyor belt 21 in the direction of arrow A. The paper is conveyed in the paper direction (this conveyance path is referred to as a first conveyance path 61). Then, the conveying belt 21 is rotated in the direction indicated by the arrow B, and is fed into a double-sided paper feeding unit 51 for reversing the paper 12 to form an image on the other surface of the paper 12 on which the image is formed on one surface. The double-sided paper feed unit 51 reverses and conveys the paper 12 (this conveyance path is referred to as a second conveyance path (reverse conveyance path) 62), and the paper 12 is again sent to the first conveyance path 61.
[0031]
A conveyance guide / separation claw 23 is provided between the first conveyance path 61 and the second conveyance path 62. As shown in FIG. 4, the conveyance guide / separation claw 23 integrally forms a guide surface 23 a for guiding the paper 12 toward the conveyance belt 21 and a separation surface 23 b for separating the paper 12 from the conveyance belt 21. It is a thing. As a result, the paper 12 conveyed by the rotation of the conveyance belt 21 in the direction indicated by the arrow B is separated from the surface of the conveyance belt 21 by the conveyance guide / separation claw 23 and sent to the second conveyance path 62.
[0032]
In this way, the paper 12 can be reliably separated from the transport belt 21 by the transport guide / separation claw 23 and fed into the reverse transport path 62. When the transport belt 21 is reversely rotated, the paper 12 is transported to the transport belt 21. It is possible to prevent the occurrence of a jam such as being caught on the conveyor belt 21 or being fed to the paper feed tray 10 side. In this case, separation can be performed with a simple configuration by using a separation claw as a separation mechanism.
[0033]
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same figure is principal part explanatory drawing of the embodiment.
In this embodiment, the conveyance guide / separation claw 23 is supported by a shaft 52 so as to be swingable in the direction of the arrow, and is arranged so as to be able to contact and separate from the conveyance belt 21. By doing so, the conveyance guide / separation claw 23 is brought into contact with the surface of the conveyance belt 21 only when separating the paper 12 from the conveyance belt 21 (for example, it is configured to swing directly or indirectly with a plunger). Thus, the surface of the conveyor belt 21 can be prevented from being damaged, and the durability of the conveyor belt 21 can be improved.
[0034]
Next, a third embodiment of the present invention will be described with reference to FIG. In addition, the same figure is principal part explanatory drawing of the embodiment.
Here, the separation claw 53 (which may be the conveyance guide / separation claw 23 of each of the above embodiments) is provided on a member (opening / closing member) 54 that can be opened and closed for jam removal and the like so as to be swingable by a shaft 52. Similar to the second embodiment, the conveyor belt 21 is arranged so as to be able to contact and separate.
[0035]
Further, a roller 55 as a fall restricting member is provided to restrict the fall of the separation claw 53 toward the transport belt 21 side. The roller 55 also has a function of pressing and feeding a sheet to the transport belt 21 as in the counter roller 22 of the first embodiment.
[0036]
That is, when the separation claw 53 is swingably provided on the opening / closing member 54, when the opening / closing member 54 is opened and the jamming is removed as shown in FIG. As shown in FIG. 5B, the separation claw 53 may collide with the surface of the conveyor belt 21 and damage the conveyor belt 21. Therefore, the conveyance belt 21 can be prevented from being damaged by regulating the fall of the separation claw 53 with the roller 55 as the fall regulating member.
[0037]
In this case, by using the fall restricting member as a roller member, paper feeding can be performed, and the number of parts can be reduced.
[0038]
In the above embodiment, the separation claw is used as the separation mechanism. However, for example, an air separation mechanism by blowing air can be used. Further, although the present invention has been described with reference to an example in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage, the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.
[0039]
The image forming apparatus according to the present invention can be applied to a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, etc., in addition to an ink jet printer. Furthermore, the present invention can also be applied to an image forming apparatus that discharges a liquid other than ink, such as a resist or a DNA sample in the medical field.
[0040]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the conveyance belt is rotated in the direction opposite to the conveyance direction for forming an image on one surface of the recording medium, and is moved to the other surface of the recording medium. An image forming apparatus that feeds a recording medium to a reversal conveyance path for reversing the recording medium to form an image, and includes a separation mechanism that separates the recording medium from the conveyance belt to send the recording medium to the reversal conveyance path. The recording medium can be reliably separated from the conveying belt, jamming due to poor separation can be prevented, and more stable duplex printing is possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic plan view of a main part of the recording apparatus. 4 is an explanatory view for explaining a conveyance guide / separation claw of the recording apparatus. FIG. 5 is an explanatory view of a main part for explaining a second embodiment of the invention. FIG. 6 is for explaining a third embodiment of the invention. Main part explanatory diagram to be provided [FIG. 7] Main part explanatory diagram to explain the operation of the embodiment [description of reference numerals]
DESCRIPTION OF SYMBOLS 3 ... Carriage, 4 ... Recording head, 12 ... Paper, 21 ... Conveyance belt, 22 ... Counter roller, 23 ... Conveyance guide / separation claw, 26 ... Charging roller, 27 ... Conveyance roller, 28 ... Tension roller, 44 ... Discharge Tray, 53 ... separation claw, 54 ... opening / closing member, 55 ... roller.

Claims (5)

An inversion that reverses the recording medium by rotating the conveying belt in a direction opposite to the conveying direction for forming an image on one surface of the recording medium. In the image forming apparatus to be sent to the conveyance path,
A separation claw for separating the recording medium from the conveyance belt and feeding it to the reverse conveyance path ;
The image forming apparatus , wherein the separation claw is swingably held by an openable / closable member that covers a portion for separating the recording medium . The image forming apparatus according to claim 1 , wherein the separation claw is disposed so as to be able to come into contact with and separate from the surface of the conveyance belt. 3. The image forming apparatus according to claim 1 , further comprising a fall restriction member that regulates the fall of the separation claw. 4. The image forming apparatus according to claim 3 , wherein the fall regulation member is a roller member. The image forming apparatus according to claim 4, wherein the roller member has a function of pressing the recording medium against the conveyance belt.

Images