JP2002053256A - Suction type sheet carrier, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suction type sheet carrier capable of preventing degradation of the suction force irrespective of the sheet carrying position and consistently carrying the sheet. SOLUTION: This suction type sheet carrier and this image forming device comprise a sheet carrying means for carrying a sheet, and a sucking means for sucking air. In the suction type sheet carrier for carrying the sheet along a holding surface of the sheet carrying means by the negative pressure by sucking air by the sucking means, a shutter is provided between the holding surface of the sheet carrying means and an air intake port of the sucking means, the shutter is movable in the sheet carrying direction, and the shutter is moved according to the sheet carrying position so as to close a part of the air intake port having no sheet placed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction type sheet conveying device used in an image forming apparatus, and more particularly to a stable sheet conveying method.

[0002]

2. Description of the Related Art Conventionally, in a printer that records on various sheets such as a printing sheet and a transparent sheet for OHP, a transport roller that sandwiches and transports a sheet between two rollers that rotate while closely contacting each other is often used. Have been. A plurality of such transport rollers are provided in the printer, and perform a series of printer steps.

In an ink jet printer that performs recording using a liquid or hot-melt ink, it is necessary to keep a distance between a recording head and a sheet moving while discharging ink narrow and constant. This is because if the distance between the recording head and the sheet changes, the image will be distorted, and if the sheet comes into contact with and rubs against the recording head, the recording surface may be stained. Therefore, deformation of the sheet before recording,
In order to eliminate the deformation of the sheet due to the effect of the ink that has been ejected and attached, a conveyance roller or a leaf spring-like member is provided at a position adjacent to the recording head to suppress the deformation of the sheet and reduce the distance between the recording head and the sheet. Kept constant.

However, if the ink is ejected from the recording head and adheres to the sheet immediately after the sheet is sandwiched between the conveying rollers and the leaf spring-shaped member, the ink is dried and solid on the surface of the sheet or inside the sheet due to the nature of the ink. Since the rollers and the like come into contact with each other before the conversion, the recorded characters and figures are deformed. Therefore, conventionally, a sheet conveying device as shown in FIGS. 11 and 12 has been used.

[0005] In FIG. 11, a transport belt 100 composed of an endless belt is stretched around two rollers 101, and is driven to rotate by driving means (not shown). A plurality of ventilation holes 100a are formed in the conveyor belt 100 in a region around the width of the sheet S over the entire circumference, and an intake port 102 of a plenum (space) 102 is provided inside the conveyor belt 100 as shown in FIG.
a is arranged. A suction fan 103 is connected to the plenum 102, and is configured to suck outside air through an intake port 102a and a ventilation port 100a.

The intake port 102a is a recording head of the conveyor belt 100.
It opens toward the sheet holding surface facing 104,
The sheet S is attracted by placing the sheet S on the transport belt 100, and is transported by rotating the transport belt 100 in this state. By performing recording with the recording head 104 while suction-conveying in this manner, the sheet can be conveyed without deformation, and high-quality image formation can be performed.

[0007]

In the above-mentioned conventional configuration, when the sheet S is conveyed to a position where the intake port 102a of the plenum 102 is completely closed, the inside of the plenum 102 is closed and the negative pressure is increased. The sheet S can be transported most stably.

However, at a position where the sheet S only blocks the intake port 102a of the plenum 102 at the front end or the rear end, outside air is sucked from the open portion of the intake port 102a. Therefore, there is a problem that the negative pressure in the plenum 102 does not increase and the suction force does not increase, so that the sheet S cannot be stably conveyed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a suction-type sheet conveying apparatus capable of preventing a decrease in suction force regardless of a sheet conveying position and stably conveying a sheet.

[0010]

In order to solve the above-mentioned problems, a typical configuration of a suction-type sheet conveying apparatus and an image forming apparatus according to the present invention includes a sheet conveying means for conveying a sheet, and air suction. A suction-type sheet conveying apparatus that has a suction unit and conveys a sheet along a holding surface of the sheet conveying unit by a negative pressure that suctions air. A shutter provided between the air inlets of the means, the shutter being movable in a sheet conveying direction, and moving the shutter in accordance with a sheet conveying position so as to close a portion of the air inlet where no sheet is loaded. It is characterized by making it.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a suction type sheet conveying apparatus and an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus, FIGS. 2 and 3 are diagrams illustrating the operation of a suction-type sheet conveyance device, FIG. 4 is a side cross-sectional view of the suction-type sheet conveyance device, and FIG. Illustration, FIG. 6
3 is a block diagram of the image forming apparatus.

(Apparatus Configuration) FIG. 1 shows an image forming apparatus employing an ink jet system, which forms an image by discharging ink onto a sheet S conveyed by an ink jet recording head 1. The sheet S is the transport belt 2,
The sheet is conveyed by sheet conveying means including a suction fan 8, a plenum 9, and the like.

In the sheet conveying apparatus according to the present embodiment, a conveying belt 2 as a sheet conveying means is an endless belt, stretched by two rollers 3 and driven to rotate by a driving means (not shown). A plurality of ventilation openings 2a are formed in the conveyance belt 2 in a region around the width of the sheet S over the entire circumference, and an intake 9a of a plenum (space portion) 9 is arranged inside the conveyance belt 2 as shown in FIG. Have been. A suction fan 8 is connected to the plenum 9 and sucks outside air through an intake port 9a and a ventilation port 2a.
The suction fan 8 and the plenum 9 constitute suction means.

The intake port 9a opens toward the sheet holding surface of the transport belt 2 which faces the recording head 1 described later, and opens at least an area about the width of the sheet as shown in FIG. That is, the sheet S is transferred to the transport belt 2
, The sheet S is attracted to the holding surface of the transport belt 2 and an image is formed while being transported by rotating the transport belt 2 in this state.

A shutter belt 4 is disposed inside the conveyor belt 2 and on the outer periphery of the intake port 9a of the plenum 9. As shown in FIG. 5, the shutter belt 4 has a shutter 4a for blocking air flow and a mesh 4b for passing air.
Endless belt, and two rollers 5 driven to rotate by a shutter motor 46 (see FIG. 6).
It is stretched by. A hole 4c for meshing with a gear provided on the roller 5 is formed at a side end of the shutter belt 4, and a photo interrupter 10 for detecting the position of the shutter 4a is provided on the shutter belt 4.

FIG. 6 is a block diagram of the entire image forming apparatus. The image forming apparatus according to the present embodiment is an inkjet printer as described above,
PU32 has ROM33, RAM34, timer 35, clock
36, and is connected to an A / D converter 37. The print image data input from the host PC 30 is sent to the gate array 39 via the I / F 38, and the gate array 39 outputs the print data generated by the HV conversion to the print head 1. The gate array 39 has a D which is used as a buffer when the print image data is subjected to HV conversion.
A print head 1 that has a RAM 40 and an SRAM 41 that is a buffer for storing print data to be output to the print head 1, and that ejects ink based on the HV converted print data
It is connected to the. The recording head 1 transmits rank data, which is individual difference data of the resistance value of the recording head 1, and temperature data of the recording head 1 to the CPU 32 via the A / D converter 37 by the LICC 42. The printer 31 is connected to the external A
It has a low-voltage power supply 43 and a power switch 44 supplied with power from the C input.

The CPU 32 controls the suction fan 8 and the shutter motor 46. Reference numeral 45 denotes a driver IC 45 for driving the shutter motor 46. CPU is a photo interrupter
The timing at which the shutter 4a passes the fixed position is detected by the flag 10 and the flag provided at the tip of the shutter 4a, and the CPU 32 can detect the position of the shutter 4a by how much the shutter motor 46 has been driven from the fixed position.

(Sheet Conveying Operation) Next, the operation will be described. First, as shown in FIG. 1, when the leading end of the sheet S starts to be applied to the intake port 9a on the upper surface of the plenum 9, the shutter 4a
Closes the intake port 9a where the sheet S is not placed. Then, the CPU 32 controls the shutter motor 46 so that the shutter 4a advances in the advancing direction in synchronization with the sheet S. As a result, the inside of the plenum 9 is sealed, the negative pressure increases, and the suction force increases, so that the sheet S can be stably conveyed.

Next, as shown in FIG. 2, when the sheet S is conveyed to a position where all the intake ports 9a of the plenum 9 are closed, the inside of the plenum 9 is sealed by the sheet S, the negative pressure increases, and the suction force increases. It is possible to increase and stably convey the sheet S. At this time, as shown in FIG. 2, the shutter 4a may be at any position other than the intake port 9a.

Then, as shown in FIG. 3, the shutter 4a closes the intake port 9a of the portion where the sheet S is not placed from the time when the rear end of the sheet S is applied to the intake port 9a on the upper surface of the plenum 9 until the rear end is finished. The CPU 32 controls the shutter motor 46 so that the shutter 4a advances in the advancing direction in synchronization with the sheet S. Accordingly, the inside of the plenum 9 is sealed, the negative pressure increases, the suction force increases, and the sheet S can be stably conveyed.

[Second Embodiment] Next, a second embodiment of a suction type sheet conveying apparatus and an image forming apparatus according to the present invention will be described. FIG. 7 is a schematic configuration diagram of the image forming apparatus, and FIG.
And FIG. 9 is a diagram for explaining the operation of the suction type sheet conveying device.
FIG. 10 is a side cross-sectional view of the suction-type sheet conveying device. The same reference numerals are given to the same portions as those in the first embodiment, and the description is omitted.

(Apparatus Configuration) In the first embodiment described above, the conveying belt 2 which is an endless belt has been described as the sheet conveying means. However, the present invention is not limited to this. Holding plate 7 as a member
May be used.

As shown in FIG. 7, in this embodiment, the transport belt 2 is not provided, and a holding plate 7 is provided at a position facing the recording head 1. A plurality of ventilation ports 7a are formed in the holding plate 7 in a region about the width of the sheet S, and an intake port 9a of the plenum 9 is opened below the ventilation ports 7a. As shown in FIG. 10, the intake port 9a opens a region about the width of the sheet S, and the outside air is sucked by the plenum 9 so that the sheet S is held by the holding plate 7 through the intake port 9a and the ventilation port 7a. Adsorbed on the surface. An image is formed by the recording head 1 while the sheet S is stably conveyed along the holding surface by conveying the end of the sheet S by the conveying roller 11.

A shutter belt 4 is provided between the holding plate 7 and the intake port 9a of the plenum 9. The shutter belt 4 is an endless belt that covers the outer periphery of the intake port 9a of the plenum 9 as in the first embodiment, and connects a shutter 4a that blocks air flow and a mesh 4b that allows air to flow, and a shutter motor 46 (see FIG. 6), and is stretched by two rollers 5 driven to rotate.

(Sheet Conveying Operation) Next, the operation will be described. First, as shown in FIG. 7, the shutter 4a closes the intake port 9a in a portion where the sheet S is not placed from the time when the leading end of the sheet S is applied to the intake port 9a on the upper surface of the plenum 9 until the end thereof. The CPU 32 controls the shutter motor 46 so that the shutter 4a advances in the advancing direction in synchronization with the sheet S. As a result, the inside of the plenum 9 is sealed, the negative pressure increases, and the suction force increases, so that the sheet S can be stably conveyed.

Next, as shown in FIG. 8, when the sheet S is conveyed to a position where all the intake ports 9a of the plenum 9 are closed, the inside of the plenum 9 is sealed, the negative pressure increases, and the suction force increases. The sheet S can be stably conveyed. At this time, as shown in FIG. 8, the shutter 4a may be at any position other than the intake port 9a.

As shown in FIG. 9, the shutter 4a closes the intake port 9a where the sheet S is not placed until the rear end of the sheet S is applied to the intake port 9a on the upper surface of the plenum 9 and the sheet S is completely stopped. The CPU 32 controls the shutter motor 46 so that the shutter 4a advances in the advancing direction in synchronization with the sheet S. Accordingly, the inside of the plenum 9 is sealed, the negative pressure increases, the suction force increases, and the sheet S can be stably conveyed.

[0028]

As described above, in the suction-type sheet conveying apparatus and the image forming apparatus according to the present invention, the shutter is provided between the holding surface of the sheet conveying means and the suction port of the suction means. The pressure for sucking the sheet irrespective of the sheet conveyance position by moving the shutter in accordance with the sheet conveyance position so as to close the portion of the intake port on which the sheet is not loaded. Can be prevented, and the sheet can be stably conveyed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus.

FIG. 2 is a diagram illustrating the operation of a suction-type sheet conveying device.

FIG. 3 is a diagram illustrating the operation of a suction-type sheet conveying device.

FIG. 4 is a side sectional view of the suction type sheet conveying device.

FIG. 5 is a diagram illustrating a configuration of a shutter belt.

FIG. 6 is a block diagram of the image forming apparatus.

FIG. 7 is a schematic configuration diagram of an image forming apparatus.

FIG. 8 is a diagram illustrating the operation of the suction-type sheet conveying device.

FIG. 9 is a diagram illustrating the operation of the suction type sheet conveying device.

FIG. 10 is a side sectional view of the suction type sheet conveying device.

FIG. 11 is a diagram illustrating a conventional image forming apparatus.

FIG. 12 is a side sectional view of a conventional suction type sheet conveying device.

[Explanation of symbols]

 S: Sheet 1 ... Recording head 2 ... Conveying belt 2a ... Ventilation opening 3 ... Roller 4 ... Shutter belt 4a ... Shutter 4b ... Mesh 4c ... Hole 5 ... Roller 7 ... Holding plate 7a ... Ventilation opening 8 ... Suction fan 9 ... Plenum 9a … Intake port 10… Photo interrupter 30… Host PC 31… Printer 32… CPU 33… ROM 34… RAM 35… Timer 36… Clock 37… A / D converter 38… I / F 39… Gate array 40… DRAM 41… SRAM 42 LICC 43 Low voltage power supply 44 Power switch 45 Driver IC 46 Shutter motor

Claims (4)

[Claims] 1. A sheet conveying means for conveying a sheet, and a suction means for sucking air, wherein the suction means conveys the sheet along a holding surface of the sheet conveying means by a negative pressure for sucking air. A suction sheet conveying device, wherein a shutter is provided between a holding surface of the sheet conveying means and an air inlet of the suction means, the shutter is movable in a sheet conveying direction, and the shutter is moved to the sheet of the air inlet. A sheet conveying device for moving a sheet according to a sheet conveying position so as to cover a portion where no sheet is placed. 2. The suction type sheet conveying device according to claim 1, wherein the sheet conveying means is an endless belt. 3. The suction type sheet conveying apparatus according to claim 1, wherein the sheet conveying means includes a plate-shaped member having the holding surface and a conveying roller. 4. An image forming apparatus, comprising: recording means for recording an image on a sheet; and the sheet conveying device according to claim 1.