JPH03128267A - Sheet feed device and recording device using same feed device - Google Patents

Abstract

PURPOSE:To transport sheet accurately and thereby prevent it from becoming creased or running obliquely by providing a drive roller with a high friction factor for the sheet and a driven roller with a low friction factor for the sheet and transporting the sheet between these rollers. CONSTITUTION:A drive roller 12 has a rough surface, and juts on the surface of the drive roller 12 biting into recording paper 30 partially, and thus a frictional force between the recording paper 30 and the drive roller 12 increases, when the drive roller 30 is pressed against the paper 30 with a pressing force. In the meantime, the driven roller 13 has a softer silicone rubber than the surface of the drive roller 12. In addition, the surface of the driven roller 13 has a polymer film layer such as 'Teflon(R)' in order to minimize the frictional factor. Subsequently, the force applied to the paper 30 by the driven roller 13 is so small that it equals or lower than half the value of the frictional force generated by the drive roller 12. Furthermore, the driven roller 13 does not become a resistance to the transport of the paper 30 as the roller 13 is installed on a lever 15 so that the former rotates with a minimum frictional resistance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies a sheet feeding device for conveying recording sheets, original sheets, etc., used in recording devices such as printers and facsimile machines, and the sheet feeding device. The present invention relates to a recording device.

[Prior Art] In a thermal transfer printer, for example, which performs color recording by conveying a recording sheet back and forth, the recording sheet is sandwiched between two rollers, and one of the rollers is driven to rotate to convey the recording sheet. It is configured.

[Problems to be Solved by the Invention] However, in the above conventional example, the undriven roller (
The conveyance of the recording sheet became unstable due to the relationship between the frictional force between the driven roller) and the drive roller, and the amount of conveyance could not be accurately controlled. In particular, if there are slight variations in the surfaces of the two rollers (surface roughness, difference in diameter, etc.), the recording sheet will be conveyed wrinkled or skewed, making it impossible to convey the recording sheet accurately. There wasn't. Since a roller that eliminates such variations is expensive to manufacture, there is a problem in that if it is used in a printer or the like, the cost of the device will increase.

The present invention has been made in view of the above-mentioned conventional example, and it is an object of the present invention to provide a sheet feeding device that can accurately convey sheets, and a recording device to which the sheet feeding device is applied.

[Means for Solving the Problems] In order to achieve the above object, the sheet feeding device of the present invention has the following configuration. That is, a sheet feeding device that conveys the sheet by sandwiching the sheet between rotating bodies,
a driving means for rotationally driving the first rotating body; and a second rotating body that is pressed against the first rotating body via the sheet and rotates as the sheet is conveyed, the first rotating body The friction coefficient of the surface of the second rotating body is made sufficiently larger than the friction coefficient of the surface of the second rotating body.

Further, a recording device according to another invention has the following configuration. That is, in a recording device that records an image on a recording sheet, the first
a driving means for rotationally driving a rotating body; and a driving means that is pressed into contact with the first rotating body via the recording sheet, rotates as the recording sheet is conveyed, and has a friction coefficient greater than a friction coefficient of the surface of the first rotating body. The apparatus includes a second rotating body having a sufficiently small surface friction coefficient, and a recording means for recording an image on the sheet that is conveyed while being sandwiched between the first and second rotating bodies.

[Operation] In the sheet feeding device configured as described above, the first rotating body among the rotating bodies is rotationally driven by the driving means. This first
a second rotating body that is pressed into contact with the rotating body through a sheet and rotates as the sheet is conveyed, and the coefficient of friction on the surface of the first rotating body is expressed as the coefficient of friction on the surface of the second rotating body. It is sufficiently larger than .

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Description of Color Thermal Transfer Printer] FIG. 1 is a conceptual diagram showing the configuration of a recording section of a color thermal transfer printer according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the schematic configuration of the color thermal transfer printer.

In Fig. 1, 10 is a line type thermal head;
One line of heating elements is arranged in the vertical direction of the drawing. 1
A platen 1 holds a recording paper 30 facing the thermal head 10. Reference numeral 12 denotes a recording paper conveyance roller, the surface of which is made of, for example, metal, and is uniformly roughened by sandblasting or other finishing. Reference numeral 13 denotes a driven roller that rotates as the recording paper 30 is conveyed, and its surface is finished to reduce the coefficient of friction. This driven roller 13 is attached to a lever 15 that swings about a shaft 17, and the driven roller 13 is pressed against the recording paper conveying roller by the action of a spring 16.

Reference numeral 14 denotes a recording sheet conveying motor that drives the recording sheet conveying roller 12 in forward and reverse rotation.

18 is a recording paper roll that winds the recording paper 30; 19 is a recording paper rewinding motor connected to the rotating shaft of the recording paper roll 18; when the recording paper 30 is conveyed in the forward direction (arrow H direction); applies pack tension to prevent wrinkles from occurring in the recording paper 30, and when rewinding the recording paper 30 in the direction of arrow J, drives the recording paper roll 18 to rotate in the opposite direction.

2o is an ink sheet supply roller which winds a color ink sheet 29 as shown in FIG. Reference numeral 21 denotes an ink sheet take-up roll, which is rotationally driven by an ink sheet take-up motor 22 and winds up the ink sheet portion used for thermal transfer recording. The thermal head 10 is attached to a head shift lever 23 that can swing around a shaft 24, and the platen 11 is moved by the action of a spring 25.
is pressed against. A solenoid 26 applies a force in a direction to the head shift lever 23 to release the thermal head 23 from being pressed against the platen 11. 27 is a cutter for cutting the recorded recording paper 3o. Reference numeral 28 denotes an ink sheet sensor for detecting the color code of the ink sheet and locating the beginning of the ink portion.

FIG. 3 is a diagram showing an example of the color ink sheet 29.
9Y, 29M, and 29C (7) are color code parts for locating the beginning of each color of yellow, magenta, and cyan, and by reading these codes with the ink sheet sensor 28, locating the beginning of each color part can be performed. can. 31
Y, 31M, 31C are yellow, magenta,
This is a portion where ink of each color of cyan is applied onto a polyethylene film serving as a base material of the ink sheet 29.

In FIG. 2, 101 is an input interface unit for receiving recorded data from an external device such as a host computer, and 102 is a page memory that stores at least 1 page of recorded data.
The recording data inputted through 01 is stored in a bitmap image data format for printing. 103 is a control unit for controlling the entire thermal transfer printer of the embodiment;
CPUI 11, CPUII such as microprocessor
RAM 112 used as the work area of I, the fourth
It includes a ROM 113 that stores a control program for the CPU 11 and various data as shown in the flowchart of the figure. 1.4 is a recording section of the printer, and parts common to those in FIG. 1 are indicated by the same symbols, and their explanation will be omitted.

With the above configuration, when record data for one page, for example, is stored in the page memory 102, the control unit 103 instructs the recording unit 104 to start recording. The control unit 103 uses the ink sheet sensor 28 to check whether the desired color portion of the ink sheet 29 is in the recording position, and if it is not in the recording position, it rotates the ink sheet winding motor 22 to transport the ink sheet 29. do.

In this way, when the desired color portion is conveyed to the recording position, transfer recording is performed while conveying the recording paper 30 and the ink sheet.

When the recording of one color is completed, the recording paper 30 is
Rewind by a page and then perform transfer recording in a different color. By performing these processes for each color (three colors), color recording can be performed on the recording paper 30.

[Operation Description (FIGS. 1 to 4)] Next, the printing process by the color thermal transfer printer of this embodiment will be described with reference to the flowchart of the recording process in FIG. 4.

This flowchart is started when record data for one page is stored in the page memory 102, and a host computer (not shown) instructs the start of print processing.

First, in step S1, the ink sheet winding motor 22 is driven based on a signal from the ink sheet sensor 28 to select a desired color portion (for example, yellow portion 3) of the ink sheet 29.
1Y).

At this time, the solenoid 26 is energized, the thermal head 10 is separated from the platen 11, and the recording paper 30 is pulled out from the supply roll 18 via the platen 11, and is held between the conveyance roller 12 and the driven roller 13. ing.

Next, the process advances to step S2, and the recording paper rewind motor 19 is energized to apply a pulling force to the recording paper 30 in the direction opposite to the direction in which the recording paper 30 is pulled out (direction of arrow H). Pack tension is applied to the recording paper 30 to prevent the recording paper 30 from sagging between the driving roller 12 and the platen 11. Then, the energization to the solenoid 26 is released, and the thermal head 1° is brought into pressure contact (down) with the platen 11 by the action of the spring 25.

This completes the preparation for the recording operation, and from this point forward, the recording paper 30 and the ink sheet 29 are each transported, and the thermal head 10 performs transfer recording.

Here, the conveyance operation of the recording paper 30 will be explained. As mentioned above, the surface of the drive roller 12 is roughly finished. Therefore, when the drive roller 12 is pressed against the recording paper 30 with a pressure force F, the protrusion on the surface of the drive roller 12 partially bites into the recording paper 30, causing friction between the recording paper 30 and the drive roller 12. Power increases. If the coefficient of friction at this time is μ, a force of μ·F is applied to the recording paper 30,
This becomes the conveyance force for the recording paper 30.

On the other hand, the surface of the driven roller 13 is similar to that of the driving roller 12.
The surface of the silicone rubber is made of silicone rubber, which is softer than the surface of the rubber, and a polymer film layer such as Teflon is formed on the surface of the silicone rubber to further reduce the coefficient of friction. Therefore, if the coefficient of friction between the driven roller 13 and the recording paper 30 is μ, then the driven roller 13 applies a force μ゛f to the recording paper 30. This force μf is very small, less than half of the frictional force μ·F of the driving roller 12 described above, and the driven roller 13 is
Since the driven roller 13 is mounted so as to reduce the frictional resistance of rotation, the driven roller 13 does not become a resistance when the recording paper 30 is conveyed. Therefore, the amount of conveyance of the recording paper 30 is determined by the radius and amount of rotation of the drive roller 12 when the drive roller 12 is driven to rotate.

Note that if the surface of the drive roller 12 is uneven,
It is conceivable that force is applied to the recording paper 30 not only in the tangential direction but also in the axial direction of the drive roller 12, causing the recording paper 30 to wrinkle or skew. However, in this embodiment, since the friction coefficient of the driven roller 13 is made small,
The axial force applied to the recording paper 30 is no longer maintained, and it is possible to prevent the recording paper 30 from being wrinkled or skewed.

Next, returning to the flowchart of FIG. 4 again, the recording paper feed motor 14 is rotated in the forward direction to convey the recording paper 30 by one line. Then, in step S4, the ink sheet take-up motor 22 is driven to rotate to convey the ink sheet 29, and one screen worth of transfer recording in, for example, yellow is performed. When the transfer recording for one screen is completed in this way, the process proceeds to step S5, where the rotation of the recording paper feed motor 14 is stopped and the rotation of the drive roller 12 is stopped.

Next, the process proceeds to step S6, where the solenoid 26 is energized to move the thermal head 10 up (separated from the platen 11), and in step S7, it is checked whether the transfer recording using the three color inks has been completed. If the three-color transfer recording has not been completed, the process advances to step S10, where the recording paper rewinding mechanism 19 is rotationally driven to rewind the recording paper 30 by the amount (for one screen) conveyed by the transfer recording described above. Rewind in the direction of arrow J. Then, return to step S1 again, and print the ink sheet 2.
The color to be transferred next to color 9 (for example, magenta) is located, and transfer recording is performed in steps S2 to S6 as described above.

When the three-color transfer recording is completed in step S7, the process proceeds to step S8, in which the recording paper 30 is conveyed to the cutting position by the cutter 27, and in step S29, the cutter 29 is driven to cut the recording paper 30.

As described above, by configuring the conveyance mechanism for the recording paper 30 and reducing the frictional force that the recording paper 30 receives from the driven roller 13, the conveyance amount of the recording paper 30 can be adjusted to match the radius and rotation amount of the drive roller 12. can be determined almost accurately.

Furthermore, since it is possible to prevent the recording paper 30 from being wrinkled or skewed due to slight variations in the surfaces of the driving roller 12 and the driven roller 13, it is possible to prevent the recording paper 30 from being conveyed in the forward or reverse direction, especially as in this embodiment. In the case of a color printer that performs overlapping recording, registration accuracy can be improved and high-quality images can be formed.

In this embodiment, the friction coefficient μ between the driving roller 12 and the recording paper is approximately 0.8 to 1.5, and the friction coefficient μ° between the driven roller 13 and the recording paper is approximately 0.8 to 1.5. 1~0.
It is 2. Here, the recording paper is plain paper such as copy paper. These friction coefficients vary depending on various conditions, but in this embodiment, the friction coefficient μ between the drive roller 12 and the recording paper is set to be about 10 times μ°.

Further, in this embodiment, a polymer film layer such as Teflon is provided on the surface of the driven roller 13, but the invention is not limited to this, and the driven roller 13 may be made of other materials with a small coefficient of friction. Alternatively, acid treatment or the like may be performed. Further, although silicon rubber is used as the material of the driven roller 13, other materials may be used.

Furthermore, although the drive roller 12 has been described as a metal roller,
Any material may be used as long as the deformation due to pressure contact with the driven roller 13 can be predicted and the surface friction coefficient is large, such as hard rubber.

Furthermore, although this embodiment has been described in the case of a thermal transfer printer, the present invention is not limited thereto, and can be applied to, for example, an electrophotographic printer or any device that conveys a sheet-like medium.

As explained above, according to this embodiment, a driving roller having a large friction coefficient with the recording paper and a driven roller having a small friction coefficient with the recording paper are used to convey the recording paper, and the paper is held between these rollers. By adopting a configuration for conveying the recording paper, it is possible to convey the recording paper with high precision and prevent wrinkles and skewed feeding of the recording paper.

[Effects of the Invention] As explained above, according to the present invention, sheet conveyance
By using a driving roller that has a high coefficient of friction with the sheet and a driven roller that has a low coefficient of friction with the sheet, and conveying the sheet by sandwiching it between these rollers, the sheet can be conveyed with high precision and the sheet can be It has the effect of preventing the occurrence of wrinkles and skew.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing the configuration of the recording section of the color thermal transfer printer of the example. Figure 2 is a block diagram showing the schematic configuration of the color thermal transfer printer of the example. Figure 3 is used in the thermal transfer printer of the present example. FIG. 4 is a flowchart showing the printing process of the thermal transfer printer of the embodiment. In the figure, 10... thermal head, 11... platen, 12... drive roller, 13... driven roller, 14
... Recording paper feed motor, 18... Recording paper roll, 1
9... Recording paper rewinding motor, 22... Ink sheet winding remoter, 26... Solenoid, 28...
Ink sheet sensor, 29... Ink sheet, 30.
... Recording paper, 101 ... Input interface section, 1
02...Page memory, 103...Control unit, 111
...CPU, 112...RAM, 113...RO
It is M. No.! Figure 3

Claims (6)

[Claims] (1) A sheet feeding device that conveys the sheet by sandwiching the sheet between rotating bodies, comprising: a drive unit that rotationally drives a first rotating body; a second rotating body that is pressed into contact with the sheet and rotates as the sheet is conveyed, and the coefficient of friction on the surface of the first rotating body is made sufficiently larger than the coefficient of friction on the surface of the second rotating body. Characteristic sheet feeding device. (2) A recording device that records an image on a recording sheet, comprising: a driving means for rotationally driving a first rotating body; the first rotating body is pressed into contact with the first rotating body via the recording sheet;
a second rotating body that rotates as the recording sheet is conveyed and has a surface friction coefficient that is sufficiently smaller than a surface friction coefficient of the first rotating body, and is held between the first and second rotating bodies; a recording device for recording an image on the sheet that is conveyed and transported. (3) The sheet feeding device according to claim 1, wherein the friction coefficient of the first rotating body is at least twice the friction coefficient of the second rotating body. (4) The recording apparatus according to claim 2, wherein the friction coefficient of the first rotating body is at least twice the friction coefficient of the second rotating body. (5) The first and second rotating bodies are characterized in that the lengths of the first and second rotating bodies are at least the width of the sheet.
Sheet feeding device as described in section. (6) The recording apparatus according to claim 2, wherein the lengths of the first and second rotating bodies are at least the width of the recording sheet.