JP2003237973A - Sheet conveyer, and image recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveyer and an image recorder of high reliability capable of supplying electric power stably to an electrode of a belt, even when flapping of the belt is generated in a belt end part. <P>SOLUTION: A feeder brush 5 is arranged to be evacuated to a central part side of the belt 2 by a distance 1 or more from a belt end edge, where 1 represents the distance from the end edge of the belt 2 up to a point on the belt in which an amplitude of the belt 2 caused by a flapping phenomenon gets substantially equal to an allowance amplitude determined by a performance limit of a head of the brush 5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus and an image recording apparatus suitable for being installed in an image recording apparatus such as an inkjet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, a recording medium (often paper, OHP, etc.) is ejected by ejecting ink droplets from an ejection port.
2. Description of the Related Art Inkjet recording apparatuses that perform recording on a sheet or a sheet such as cloth are known.

The ink jet recording apparatus is a non-impact type image recording apparatus, and has features such as low noise, direct recording on plain paper, and easy color image recording by using multicolor inks. It has been spreading rapidly in recent years.

Among them, an ink jet recording apparatus of the type in which thermal energy is applied to ink in accordance with a recording signal to generate a phase change and ink droplets are ejected by the acting force at that time, has a simple structure and high density multi-nozzle. It has the advantage that it is easy to obtain, and high resolution and high speed can be easily obtained.

However, in these ink jet recording apparatuses, since ink droplets are directly ejected from fine ejection openings provided on the surface (ejection surface) of the recording head facing the recording medium, in order to perform good recording. Consideration is required.
For example, in order to maintain the quality of recording, it is necessary to keep the distance between the recording head and the recording medium constant and accurately control the feeding of the recording medium. Therefore, the recording medium is attracted and held by a belt or the like, which is a conveying means, by an electrostatic force and conveyed.

As a method of transporting such a recording medium, as disclosed in Japanese Patent Laid-Open No. 147473/1987, a belt is charged in advance, the recording medium is brought into contact with the belt and attracted by an attractive force due to dielectric polarization. There is a way to do it. In addition, examples of the combined use of electrostatic force as a discharge energy source of ink droplets are disclosed in JP-A-60-46257, JP-A-62-151348, and JP-A-62-225353. In all of these, an electrode is arranged behind the recording medium (on the side without the recording head), and a voltage is applied between the electrode and the recording ink.

[0007]

In the above-mentioned conventional ink jet recording apparatus which attracts and holds the recording medium by electrostatic force, ink is ejected at the same time as the sheet is conveyed. Can be discharged by the conductive ink. In view of this point, a sheet conveying device as shown in FIG. 6 has been devised.

The sheet conveying apparatus shown in FIG. 6 has an electrode pattern 1
The belt 102 with the two rollers 130, 14
It has a structure stretched to zero. Then, the recording medium is attracted to the belt surface by applying a high voltage to the electrode pattern 121 by the power feeding brush 105. According to this method, even if a large amount of ink droplets are applied onto the recording medium, the belt 1
Since the electric charge on 02 is supplied from the outside, the belt 102
The adsorption power of does not decrease.

FIG. 7 shows the structure of the belt 102. FIG. 3A is a plan view of the belt 102, FIG.
(C) is a side view. This belt 102 has a base material 12
An electrode pattern 121 is disposed on the zero, and a dielectric layer 122 is further disposed thereon. One end of the electrode pattern 121 is exposed from the dielectric layer 122, and this portion becomes the electrode 121a. The power supply brush 105 in FIG. 6 is in contact with the electrode 121a portion, and it is possible to continue supplying the electric charge.

The belt 102 having such a structure is manufactured by pasting the electrode pattern 121 and the dielectric layer 122 on the base material 120. At the time of sticking work, due to the difference in the coefficient of thermal expansion of the sticking material, the belt peripheral length at the part where only the base material 120 at the belt end part and the part where the base material 120 and the dielectric layer 122 are stuck at the belt center part are Will be different. When the base material 120 is polyimide and the dielectric layer 122 is a fluororesin, the peripheral length of the belt end portion is longer than the peripheral length of the belt central portion. For this reason, the polyimide portion becomes wavy at the end of the belt.

Supplying electric charges to the portion of the belt end portion where the wavy state occurs by the power feeding brush 105 may cause various problems.

For example, the power feeding brush 105 and the electrode 121
Since the distance a changes, the power supply brush 105 and the electrode 12
There may be a case where 1a does not contact. In this case, the suction force weakens and the recording medium floats, which may cause a jam.

Further, since the distance between the power feeding brush 105 and the electrode 121a changes, the power feeding brush 105 and the electrode 121a change.
A state occurs in which and come into contact and non-contact repeatedly, and as a result,
The power supply brush 10 is caused by the discharge phenomenon caused by the applied high voltage.
5 and the electrode 121a. This discharge may cause a malfunction in external equipment such as malfunction of electronic equipment. In addition, when discharge occurs, the power supply brush 105
Melts due to the heat of discharge, resulting in a shorter life.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stable power supply to the electrodes of the belt even when undulation occurs at the end of the belt. An object of the present invention is to provide a highly reliable sheet conveying device and an image recording device.

[0015]

In order to achieve the above object, in the present invention, a belt having an electrode, which conveys a sheet while adsorbing a sheet by the electrode, and a flexible member contact the electrode. In a sheet conveying device provided with a power supply unit that contacts and applies a voltage to the electrode, from the edge of the belt,
When the distance to the position where the amplitude of the belt is substantially equal to the allowable amplitude determined by the performance limit of the flexible member of the power feeding means is l, the power feeding means is at least a distance l from the edge of the belt at the center of the belt. It is characterized in that it is arranged on the side.

It is preferable that the power feeding means is arranged at each of both widthwise end portions of the belt.

It is preferable that the feeding means arranged at one end of the belt applies a positive voltage and the feeding means arranged at the other end applies a negative voltage.

The power supply means is preferably a power supply brush.

It is preferable to further include a deviation detecting means for detecting the deviation of the belt, and a deviation correcting means for correcting the deviation of the belt based on a detection result of the deviation detecting means.

Further, the image recording apparatus of the present invention is characterized in that an image is recorded on the sheet conveyed by the sheet conveying apparatus by using the image recording means.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto.

FIG. 1 is a schematic diagram showing a schematic configuration of an image recording apparatus (inkjet recording apparatus) according to an embodiment of the present invention.

The ink jet recording apparatus 10 generally includes a sheet feeding cassette 11 and a sheet feeding tray 12 as sheet stacking means, a feeding roller 13 as a feeding means for separating and feeding the sheet P from the sheet feeding cassette 11, and a sheet feeding. A feeding roller 1 as a feeding unit that separates and feeds a sheet from the tray 12.
4, a sheet conveying device 1 that conveys the separated and fed sheet P, a recording head 15 as an image recording unit that records an image on the sheet that is being conveyed, and a discharge unit that discharges the recorded sheet to the outside of the machine. It is configured to have a pair of discharge rollers 16 and a discharge tray 17 as discharge sheet stacking means for stacking discharged sheets.

The recording head 15 is a recording head of a type in which thermal energy is applied to ink to cause film boiling, and a pressure change caused by growth or contraction of bubbles due to the film boiling is used to eject ink from an ejection port. .

In this structure, when the image recording operation is started, the feeding roller 13 first rotates and the paper feeding cassette 1
One sheet P is picked up from the sheet bundle stacked on the sheet 1. The feeding roller 13 rotates until the sheet P is fed into the sheet conveying apparatus 1.

The sheet P is conveyed below the recording head 15 while being attracted to the belt surface of the sheet conveying apparatus 1.
The configuration of the sheet conveying device 1 will be described later.

The recording head 15 controls the ejection of ink according to the image signal and records an image on the sheet P.

The sheet P on which the image is recorded is nipped and conveyed by the pair of discharge rollers 16 and is discharged onto the discharge tray 17.

Next, the sheet conveying device 1 according to the present embodiment will be described with reference to FIGS.

FIG. 2 is a side view showing a schematic structure of the sheet conveying apparatus 1. 3A is a plan view seen from above in FIG. 2, and FIG. 3B is a side view seen from the left side in FIG.

The sheet conveying apparatus 1 is roughly composed of a driving roller 3
And a hollow cylindrical endless belt 2 is stretched around the control roller 4. The rotational force from the drive motor 8 is transmitted to the rotary shaft 30 of the drive roller 3 via the gear 80, rotates the drive roller 3 at a predetermined transport speed, and transports the belt 2.
The control roller 4 is driven to rotate as the belt 2 is conveyed.

The belt 2 has a structure in which an electrode pattern 21 is arranged on a base material 20 and a dielectric layer 22 is further arranged thereon. The electrode pattern 21 has a shape in which the end portions alternately extend to the belt end portion, and a portion of the electrode pattern 21 that is closest to the belt end portion is exposed from the dielectric layer 22. This portion becomes the power supply electrode 21a. In the present embodiment, the electrode 21a is arranged at a position closer to the belt center by 1 from the widthwise end edge of the belt 2 (retracted to the belt center side). That is, margin areas 23 (hatched portions in FIG. 3) in which the electrode patterns 21 are not arranged are provided at both ends in the width direction of the belt 2. This point will be described later.

Feeding brushes 5 and 5 as feeding means are arranged at positions corresponding to the plurality of electrodes 21a located at both ends of the upper surface of the belt 2 in the width direction. This power supply brush 5
The parts of the ears 51 are in contact with the respective electrodes 21a. Further, a positive voltage and a negative voltage are applied to the two power supply brushes 5 and 5, respectively, and a positive voltage and a negative voltage are alternately applied to the electrode pattern 21.

Further, belt deviation sensors 6 and 6 as deviation detection means for detecting deviation of the belt 2 are installed at both ends of the belt 2 in the width direction. The belt deviation sensor 6 is a photo interrupter, and is configured to detect a state where the belt 2 deviates from a predetermined position and approaches the belt deviation sensor 6.

An eccentric unit 7 is installed at one end of the rotary shaft 40 of the control roller 4 as a deviation correcting means for correcting the deviation of the belt 2. The eccentric unit 7 determines the axial position of one end of the control roller 4 when the belt deviation is detected by the belt deviation sensor 6 during the belt conveyance.
Then, control is performed to move the belt in the direction a in order to correct the belt position to a normal state (a state in which the roller is located at the center of the roller).

By the way, the structure of the power feeding brush 5 is schematically shown in FIG. That is, the power feeding brush 5 includes a portion of the brush 51 which is a flexible member for contacting and feeding power to the electrode 21a on the belt 2, and a brush fixing metal fitting 50 for fixing the brush 51 and supplying electricity. .

In order to maintain a good contact condition with respect to some vertical vibration of the belt at the time of carrying the belt, the ears 51 are
It is manufactured so as to be in contact with the electrode 21a of the belt 2 in a pressure contact state. Therefore, the ear 51 is attached in a bent state (deflected state) as shown in FIG.

The position of the contact point between the ear 51 and the ear fixing metal fitting 50 is designated as point G, and the tip portion of the ear 51 is designated as point H. In this state, the permissible fluctuation amount of the distance between the power feeding brush 5 and the belt 2 is calculated from the distance (the distance between M and K) in contact with the electrode 21a in the fully extended state of the ear 51 due to the deflection of the ear 51. The distance (distance between L and K) is obtained by subtracting the position (point H) of the performance limit of 51.

Examples of the performance limit of the ears 51 include (1) the life of the ears 51 defined by the contact pressure, and (2) the unburned residue of the ears 51 due to the amount of deflection of the ears 51.

From the above, it is necessary that the positional fluctuation amount of the electrode 21a on the belt 2 is within the distance L-K.

Next, the corrugation phenomenon at the widthwise end of the belt 2 will be described. FIG. 5 is a schematic cross-sectional view showing a state in which the belt 2 is cut in the belt width direction (direction orthogonal to the belt conveyance direction).

In the same figure, a belt width is shown between A and F, and a dielectric layer 22 made of fluororesin is stuck on the belt base material 20 between C and D.

As described above, the peripheral length of the portion only on the base material 20 without the dielectric layer 22 attached (the portion between A and C and the portion between D and F) is longer than the peripheral length of the central portion of the belt. .
Therefore, due to the difference in the circumferential length, the belt edge portion is wavy, and the belt edge portion floats in the range between X-Z1 or X-Z2. The vertical amplitude of the belt end portion at this time becomes maximum at both end edges (portions A and F) of the belt 2 which is a free end.
It becomes smaller toward the center of.

As described above, the positional fluctuation amount of the electrode 21a on the belt 2 must be within the range of the amplitude L-K due to the relationship with the performance limit of the bristle 51 of the power feeding brush 5.
In the belt 2 of FIG. 5, assuming that the amplitudes Y1 and Y2 at the points B and E are substantially equal to the amplitude L-K, the amplitude between A and B and between E and F is the amplitude L.
Since it becomes −K or more and the amplitude between B and E becomes equal to or less than the amplitude L−K, the power feeding brush 5 may be arranged in the region between B and E.

That is, the point on the belt where the amplitude of the belt due to the waving phenomenon is substantially equal to the allowable amplitude L-K determined by the performance limit of the bristle 51 of the feeding brush 5 is B.
(E), and point B (E) from belt edge A (F)
When the distance up to 1 is set to 1, the power feeding brush 5 is retracted from the belt edge A (F) to the center of the belt for a distance of 1 or more. Further, the electrode 21a on the belt 2 is also arranged to be retracted from the belt edge A (F) to the center of the belt for a distance of 1 or more, as in the case of the power feeding brush 5. Specifically, between B and C (D
Between the −E), the power supply brush 5 and the electrode 21a are arranged,
Contact power supply is performed within this area.

In the present embodiment, the electrodes 21a of the belt 2 are thus arranged in the region between B and C and between D and E as described above.
Since the contact power feeding position is provided in the area in which the amplitude of is within the range of the allowable amplitude of the bristle 51 of the power feeding brush 5, the power feeding brush 5 and the electrode 21a always maintain a good contact state.

Therefore, the suction force of the belt 2 becomes stable,
The occurrence of jam can be prevented. Further, it is possible to reduce the influence of the discharge phenomenon on the electronic device and the like, and it is possible to extend the life of the device.

[0048]

As described above, according to the present invention,
Even when undulation occurs at the end of the belt, it is possible to stably supply electric power to the electrodes of the belt, and thus it is possible to prevent jamming. Further, it is possible to reduce the influence of the discharge phenomenon on the electronic device and the like, and it is possible to extend the life of the device.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an image recording apparatus according to an embodiment of the present invention.

FIG. 2 is a side view showing a schematic configuration of a sheet conveying device according to an embodiment of the present invention.

3A is a plan view seen from above in FIG. 2, and FIG. 3B is a side view seen from the left side in FIG.

FIG. 4 is a schematic diagram showing a schematic configuration of a power feeding brush of the sheet conveying apparatus of FIG.

5A and 5B are schematic diagrams for explaining a waving phenomenon of a belt of the sheet conveying apparatus of FIG.

FIG. 6 is a perspective view showing a schematic configuration of a conventional sheet conveying device.

FIG. 7 is a schematic diagram showing a schematic configuration of a belt of a conventional sheet conveying device.

[Explanation of symbols]

1 sheet conveying device 2 belts 3 drive roller 4 control rollers 5 Power supply brush (power supply means) 6 Deviation detection sensor (deviation detection means) 7 Eccentricity unit (deviation correction means) 8 drive motor 10 Inkjet recording device (image recording device) 11 paper cassettes 12 paper trays 13 Feed roller 14 Feeding roller 15 recording head (image recording means) 16 Ejection roller pair 17 Output tray 20 Base material 21 electrode pattern 21a electrode 22 Dielectric layer 23 spare area 30 rotation axis 40 rotation axis 50 ear fixing metal fittings 51 Ears (Flexible member) 80 gear P sheet

Claims (6)

[Claims] 1. A sheet provided with a belt having electrodes, which conveys a sheet while adsorbing the sheet by the electrodes, and a power feeding means for applying a voltage to the electrodes by bringing a flexible member into contact with the electrodes. In the conveying device, when the distance from the edge of the belt to the position where the amplitude of the belt is substantially equal to the allowable amplitude determined by the performance limit of the flexible member of the power feeding means is 1, the power feeding means is Is a sheet conveying device, which is arranged on the center side of the belt at a distance of 1 or more from the edge of the belt. 2. The sheet conveying device according to claim 1, wherein the power feeding unit is arranged at each of both widthwise end portions of the belt. 3. The power feeding means arranged at one end of the belt applies a positive voltage, and the power feeding means arranged at the other end applies a negative voltage. 2. The sheet conveying device according to item 2. 4. The sheet conveying apparatus according to claim 1, wherein the power feeding means is a power feeding brush. 5. A deviation detecting means for detecting deviation of the belt, and a deviation correcting means for correcting deviation of the belt based on a detection result of the deviation detecting means. The sheet conveying device according to any one of items 1 to 4. 6. An image recording apparatus, wherein an image is recorded on a sheet conveyed by the sheet conveying apparatus according to any one of claims 1 to 5 by using an image recording unit.