JP2006347688A - Feed roller device of printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent idle turning of a driving roller when a sheet is released from a feed roller device and to prevent defective printing from occurring which obviously appears when printing a rimless photo in a feed roller device of a printer for sandwiching the sheet between the driving roller having a backlash and a driven roller for contacting and rotating with the driving roller, and feeding the sheet to a printing area. <P>SOLUTION: The driving roller 7 is one roller having a length longer than the width of the sheet D, and is driven by rotation of a driving pinion gear 12 engaged to a shaft end. The driven roller is constructed by three driven roller assembly bodies 14a, 14b, and 14c which are divided in the left, right, and the center along the longitudinal direction of the driving roller 7. The sandwiching position of the sheet D by the central driven roller assembly body 14b and the driving roller 7 is arranged to be shifted slightly forward (in the printing area direction) further than the sandwiching position of the sheet D by the left and right driven roller assembly bodies 14a and 14c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a feed roller device of a printer. Specifically, the sheet is sandwiched between a driving roller and a driven roller biased in the direction of the driving roller, and the sheet is moved to a front printing area by rotation of the driving roller. The present invention relates to a feed roller device of a printer for sending out.

  One sheet is picked up by a pick-up roller from a paper stocker loaded with a large number of sheets, and the picked-up sheet is further sandwiched by a feed roller composed of a driving roller and a driven roller, and a printing area such as an ink jet printer There are known printers that are sent to

On the other hand, there is known a sheet conveying apparatus that can pinch a sheet between upper and lower rollers and remove a curl of the sheet on the sheet conveying path by giving different feeding speeds at the center and the left and right of the sheet. (For example, refer to Patent Document 1).
JP-A-8-225221

  The feed roller device 51 including the above-described drive roller and driven roller will be described with reference to FIGS. 4 (a) and 4 (b). The drive roller 52 is a roller that is rotated by meshing a drive pinion gear 54 that is driven from a drive source such as a motor (not shown) with a gear 53 provided at its shaft end, and the driven roller 55 is not shown. This is a roller that urges the support frame 56 downward by a spring and contacts the drive roller 52 with a predetermined pressure.

  When the motor starts rotating based on a command from a control device (not shown), the rotation is transmitted from the driving pinion gear 54 to the driving roller 52 via the gear 53, and the driving roller 52 starts rotating. . Then, the paper D that has been transported to the immediate vicinity of the driving roller 52 is sandwiched between the driving roller 52 and the driven roller 55 and is sent out to the printing area E below the printing device 57. Similarly to the drive roller 52, the printing device 57 starts a printing operation such as inkjet ejection at the timing when the leading edge of the paper D reaches the printing region E according to a command from the control device. Also, the printing operation such as ink jet ejection is stopped at the timing when the trailing edge Da of the paper D passes the printing area.

  However, in the feed roller device 51 having the above-described configuration, there may be a printing failure that may be caused by a paper feed failure. Typically, when performing borderless photo printing (printing that prints on the entire surface of the paper without leaving a white portion on the edge of the paper), a white portion is generated on the edge of the paper. There was a case where a problem occurred. In that case, the quality as borderless photo printing was greatly impaired. In other words, the timing of bringing the paper D to the printing area E and the timing of starting / stopping the printing operation are slightly shifted, and printing defects such as not being printed in the areas to be originally printed at the front and rear edges of the paper D occur. There was a case.

  Therefore, the inventor of the present invention examined the above phenomenon in detail and clarified that there is the following fact as the cause of the paper feeding failure. That is, the paper D sandwiched between the driving roller 52 and the driven roller 55 is conveyed and fed as shown in FIGS. 4A to 4B at the final stage where the trailing edge Da is sent out to the printing area E. The nipping by the roller device 51 is released. At this time, in a state where the trailing edge Da of the sheet is securely held between the driving roller 52 and the driven roller 55 (FIG. 4A), the tooth surface 54a on the front side in the driving direction of the pinion gear 54 is the driving roller 52. 4 is in contact with the tooth surface 53a on the rear side in the rotational direction of the gear 53, and no backlash occurs, but at the moment when the rear end Da of the sheet is released from nipping by the driving roller 52 and the driven roller 55 (FIG. 4B). )), The tooth surface 54a on the front side in the driving direction of the pinion gear 54 is separated from the tooth surface 53a of the gear 53 of the driving roller 52, and it has been found that backlash Gb occurs.

  That is, at the moment when the trailing edge Da of the sheet is released from the nipping by the driving roller 52 and the driven roller 55, the driving roller 52 deviates from a certain rotation by the driving pinion gear 54 and slightly idles in the forward rotation direction. It has been found. Due to the idling of the drive roller 52, a play (backlash) Gb in the forward rotation direction is generated between the drive pinion gear 54 and the gear 53 of the drive roller 52, and this play Gb is the amount when the next sheet is fed. It is considered that the rotation start timing of the pinion gear 54 and the rotation start timing (paper delivery timing) of the drive roller 52 are shifted, and the delivery of the paper D is slightly delayed, causing the above-described printing failure.

  The inventor also considered various causes of the idling of the drive roller 52 described above, and elucidated as follows. That is, at the moment when the trailing edge Da of the paper is released from the nipping by the driving roller 52 and the driven roller 55, the nipping pressure Pa acting in the direction of the driving roller 52 of the driven roller 55 is shown as enlarged in FIG. Acts on the corner of the paper rear end Da, and the rear end Da of the paper is pushed forward (in the direction toward the print area E) by the horizontal component Pb of the pressure Pa. The moment when the paper D that has been securely held by the driving roller 52 and the driven roller 55 (the state shown in FIG. 4A) and has been fed forward at a constant speed leaves the feed roller device 51 by the pushing force Pb. Therefore, it is considered that the driving roller 52 idles in the forward rotation direction.

  Then, the inventor studied a method for eliminating the paper D feeding failure based on the fact that the cause of the paper D feeding failure was clarified as described above. That is, it has been considered that the component force Pb in the direction of pushing out the paper D is reduced by weakening the clamping pressure Pa of the driven roller 55 in the direction of the driving roller 52. In that case, as shown in FIG. Since the clamping pressure by the driving roller 52 and the driven roller 55 in the steady feeding state as described above becomes weak, it becomes difficult to feed the paper D at a constant speed. That is, there is an adverse effect that the feeding accuracy of the paper D itself deteriorates.

  In addition, as a fundamental solution, it is conceivable that the gear 53 of the drive roller 52 and the drive pinion gear 54 are constructed of anti-backlash type gears. Absent.

  Therefore, the present invention can be easily implemented in the feed roller device of the printer without causing other troubles such as a decrease in paper feeding accuracy or an increase in manufacturing cost, and when the paper is released from the feed roller device. It is an object of the present invention to provide a printer feed roller device that can prevent idling of the drive roller of the printer, eliminates paper feed defects, and prevents print defects that appear particularly when performing borderless photo printing. To do.

  In order to achieve the above object, the invention of claim 1 is directed to a drive pinion gear, a drive roller meshed with the drive pinion gear with a backlash, and disposed above the drive roller, and driven by a spring. A feed roller device of a printer comprising a driven roller biased in a direction in contact with the roller, and feeding a sheet sandwiched between the drive roller and the driven roller to a front print area by rotation of the drive roller; The driven roller is constituted by three driven roller assemblies divided into left and right and center along the longitudinal direction of the driving roller, and the nipping position of the sheet by the central driven roller assembly and the driving roller is The driven rollers are arranged to be shifted forward from the sheet holding position of the left and right driven roller assemblies and the drive rollers. When the trailing edge of the sheet nipped by the drive roller and fed to the printing area moves forward away from the nipping position between the left and right driven roller assemblies and the driving roller, the center of the trailing edge of the sheet Is loosely sandwiched between the center driven roller and the driving roller to prevent idling of the backlash of the driving roller.

  According to a second aspect of the present invention, there is provided a drive pinion gear, a drive roller meshed with the drive pinion gear with a backlash, and disposed above the drive roller and biased in a direction in contact with the drive roller. In a feed roller device of a printer that feeds a sheet sandwiched between the drive roller and the driven roller to a front print area by rotation of the drive roller, the driven roller is connected to the drive roller. Each is constituted by a driven roller assembly divided into three or more along the longitudinal direction, and each of the driven roller assemblies and the driving roller is not in a straight line along the driving roller. The driven roller assembly is disposed so as to be shifted in the front-rear direction, and is sandwiched between the driven roller and the driving roller, so that the printing area is When the trailing edge of the sheet to be fed out of the driven roller assembly leaves the nipping position between the driven roller assembly disposed rearward of the driven roller assembly and the drive roller, a part of the trailing edge of the sheet is the driven roller assembly. The driven roller assembly disposed forward of the body and the drive roller are in a state of being sandwiched between the bodies to prevent idling of the backlash of the drive roller.

  According to a third aspect of the present invention, in the invention according to the second aspect, among the three or more driven roller assemblies, the position of the sheet sandwiched by the driven roller assembly near the center and the driving roller is the other driven roller assembly. It is characterized by being shifted forward from the position where the sheet is held by the body and the driving roller.

  According to the present invention, a printer that sandwiches a sheet between a driving roller and a driven roller biased in a direction in contact with the driving roller, and sends the sheet to a front printing area by the rotation of the driving roller. In the feed roller device, it is possible to prevent idling of the drive roller when the paper is released from the feed roller device without causing another problem such as a decrease in paper feeding accuracy or an increase in manufacturing cost, and paper feeding. The defect is eliminated, and it is possible to eliminate a printing defect that is likely to occur particularly when borderless photo printing is performed.

  Hereinafter, a feed roller device 1 for a printer according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The printer according to this embodiment is an ink jet printer including an ink jet printing apparatus 2, and a printing area E is formed below an ink jet head 2 a of the printing apparatus 2. A paper discharge roller 3 and a star wheel 4 are provided in front of the printing area E (in the conveyance direction of the paper D and to the left in FIG. 1), and behind the printing area E (to the right in FIG. 1). A feed roller device 1 for feeding the paper D to the printing area E is disposed.

  Behind the feed roller device 1 is provided a paper supply device 6 that picks up the paper D one by one from the stacked paper by the pickup roller 5 and sends the paper D to the feed roller device 1. One sheet D picked up by the sheet supply device 6 is conveyed in a substantially horizontal posture to the discharge roller 3 through the feed roller device 1 and discharged to the front outside the printer.

  Hereinafter, the feed roller device 1 will be described in detail. The feed roller device 1 is disposed below the conveyance path of the paper D by a drive roller 7 that is rotated by a drive source such as a motor, and is disposed above the drive roller 7 and is always in contact with the drive roller 7 by a spring 8 described later. And a driven roller 9 biased in the direction (downward).

  As shown in FIG. 2, the drive roller 7 is a single roller having a length exceeding the width of the sheet. The drive pinion gear 12 is engaged with the gear 11 at the end of the rotation shaft, and the drive pinion gear 12 is engaged. When the motor 13 is rotated by the rotation of the motor 13, the driving roller 7 is rotated. The drive pinion gear 12 and the gear 11 are both spur gears, and backlash (backlash) exists between them.

  As shown in FIG. 2, the driven roller 9 includes three driven roller assemblies 14 a, 14 b, and 14 c that are divided into the left and right and the center along the longitudinal direction of the drive roller 7. Since the three driven roller assemblies 14a, 14b, and 14c have the same structure, the center driven roller assembly 14b will be described.

  The driven roller assembly 14b is rotated by a housing (not shown) supported by the support shafts 15 at both ends thereof and a swingable frame body 16 and a bearing portion 17 formed at one end of the frame body 16. A small roller body 18 that is freely provided and a spring 8 that is locked to the other end of the frame body 16 and urges the frame body 16 to rotate counterclockwise in FIG. With the above configuration, the small roller body 18 supported on one end of the frame body 16 is always urged downward (in a direction approaching the drive roller 7) with a predetermined force. One end of the spring 8 is locked to a horizontal pin 19 formed on the frame 16, and the other end of the spring 8 is locked to a housing (not shown).

  Of the three driven roller assemblies 14a, 14b, 14c, the left and right driven roller assemblies 14a, 14c are arranged at positions where the small roller body 18 contacts the apex of the driving roller 7, but are driven at the center. In the roller assembly 14b, the small roller body 18 is arranged slightly shifted from the apex portion of the driving roller 7 (in the paper D feeding direction). In other words, the three driven roller assemblies 14a, 14b, and 14c are such that each small roller body 18 does not form a straight line along the driving roller 7 in a plan view, but only the central driven roller assembly 14b. However, the small roller body 18 is arranged so as to be shifted slightly forward. In FIG. 2, it is exaggerated for convenience of explanation. The specific shift amount is about 0.5 mm.

  Next, the operation of the feed roller device 1 of this embodiment will be described. Now, when the motor 13 starts to rotate in response to a command from a control device (not shown), the drive is transmitted from the drive pinion gear 12 to the gear 11 and the drive roller 7 starts to rotate. The leading edge of the paper D brought up to just before the apparatus 1 is sandwiched between the driving roller 7 and the driven roller 9 (small roller body 18). The paper D sandwiched between the driving roller 7 and the driven roller 9 (small roller body 18) is sent to the printing region E in a horizontal posture, and is printed by the printing device 2 in which the printing operation is started by a command from the control device. Printed on the surface.

  2, when the trailing edge Da of the sheet reaches the apex of the driving roller 7, the small roller bodies 18 of the left and right driven roller assemblies 14a and 14c Since it arrange | positions so that a vertex part may be touched, the force pushed ahead with respect to the paper D with the pressure which goes to the downward direction of the small roller body 18 is added.

  However, at this time, the small roller body 18 of the center driven roller assembly 14b is disposed slightly forward of the apex portion of the drive roller 7, so that the front is slightly sandwiched from the rear end Da of the sheet. The sheet D is prevented from being pushed out.

  The operation when the rear end Da of the paper is released from the nipping of the feed roller device 1 will be further described with reference to FIG. FIG. 3 shows the moment when the trailing edge Da of the sheet passes through the nipping position between the small roller body 18 and the driving roller 7 of the left and right driven roller assemblies 14a and 14c. Is a forward force Pb (the same force as the component force Pb in FIG. 5) that pushes the paper D forward as a component of the downward force received from the small roller body 18.

  On the other hand, since the front part slightly behind the rear end Da of the sheet is sandwiched loosely by the small roller body 18 and the driving roller 7 of the center driven roller assembly 14b, the sheet D is small roller body 18 Even if the pushing force Pb is applied, the constant speed is maintained, and the pushing speed is not suddenly increased.

  Further, the pinching of the paper D by the small roller body 18 and the driving roller 7 of the center driven roller assembly 14b is loose clamping (holding by a weak force). The pinching force of the paper D by the small roller body 18 is By acting only on the center of D. The same occurs when the paper D is released from the pinching by the small roller body 18 and the driving roller 7 due to the loose clamping force of the paper D by the small roller body 18 and the driving roller 7 of the driven roller assembly 14b in the center. The force for pushing the paper D forward is also weak, and the paper D does not suddenly increase in speed and pushed forward.

  In this way, when the paper D is released from the feed roller device 1, the speed is not suddenly increased and pushed forward, so that the drive roller 7 does not idle in the forward rotation direction. Since the idle rotation of the drive roller 7 does not occur, play in the forward rotation direction between the drive pinion gear 12 and the gear 11 does not occur, and if the next rotation of the drive pinion gear 12 by the control device is started, a time lag will occur. The drive roller 7 is rotated without causing a delay in the feeding of the paper D.

  In this embodiment, the driven roller 9 is composed of three driven roller assemblies 14a, 14b, and 14c that are divided into left and right and center, but the number of divisions may be any number of four or more. For example, the driven roller 9 is constituted by five driven roller assemblies, and only one of the driven roller assemblies in the center is shifted forward (in the printing area E direction) from the other four driven roller assemblies. May be.

  As described above, when the driven roller 9 is divided into five, the two driven roller assemblies inside one from both ends may be shifted forward with respect to the other three driven roller assemblies. . In this case, as a result, the five driven roller assemblies are alternately displaced back and forth.

1 is a side sectional view of a feed roller device of a printer according to an embodiment of the present invention and a device portion before and after the device. The II-II arrow directional view in FIG. FIG. 3 is a side view showing a state at a moment when a sheet is released from nipping by a driving roller and a driven roller in the apparatus. (A) is a diagram showing a state in which the trailing edge of the sheet is clamped in the sheet feeding state by the driving roller and the driven roller in the conventional feed roller device, and (b) is a moment when the trailing edge of the sheet is released. FIG. In the conventional feed roller device, a side view for explaining the action applied to the paper at the moment when the trailing edge of the paper is released.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feed roller apparatus 2 Printing apparatus 7 Drive roller 8 Spring 9 Driven roller 11 Gear 12 Drive pinion gears 14a, 14b, 14c Driven roller assembly 18 Small roller body D Paper Da Rear end E Print area Gb Backlash

Claims (3)

A drive pinion gear, a drive roller meshed with the drive pinion gear with backlash, and a driven roller disposed above the drive roller and biased in a direction to contact the drive roller by a spring. A feed roller device of a printer that feeds a sheet sandwiched between the driving roller and the driven roller to a front printing region by rotation of the driving roller,
The driven roller is constituted by three driven roller assemblies divided into right and left and center along the longitudinal direction of the drive roller,
The nipping position of the sheet by the center driven roller assembly and the driving roller is arranged shifted forward from the nipping position of the sheet by the left and right driven roller assemblies and the driving roller,
When the trailing edge of the sheet nipped by the driven roller and the driving roller and fed to the printing area moves forward away from the nipping position between the left and right driven roller assemblies and the driving roller, A feed roller device for a printer, wherein a central portion of the end is loosely sandwiched between the driven roller and the driving roller at the center to prevent idling of the backlash of the driving roller. A drive pinion gear, a drive roller meshed with the drive pinion gear with backlash, and a driven roller disposed above the drive roller and biased in a direction to contact the drive roller, In a feed roller device of a printer that feeds a sheet sandwiched between the drive roller and the driven roller to a print area in front by rotation of the drive roller,
The driven roller is constituted by a driven roller assembly that is divided into three or more along the longitudinal direction of the drive roller, and the position where the driven roller is sandwiched between the driven roller assembly and the drive roller is in the drive roller. The driven roller assemblies are arranged so as to be shifted from each other in the front-rear direction so that they are not in a straight line.
When the trailing edge of the sheet nipped by the driven roller and the driving roller and fed to the printing area leaves the nipping position between the driven roller assembly disposed rearward and the driving roller of the driven roller assembly A part of the rear end of the sheet is sandwiched between the driven roller assembly disposed forward and the driven roller of the driven roller assembly to prevent idling of the backlash of the driven roller. A feed roller device for a printer.   Among the three or more driven roller assemblies, the position where the paper is clamped by the driven roller assembly near the center and the driving roller is shifted forward from the position where the paper is clamped by the other driven roller assemblies and the driving roller. The feed roller device for a printer according to claim 2, wherein the feed roller device is provided.

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