JP4064665B2 - Printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printer such as an ink jet printer including a plurality of fixed print heads. The invention also relates to printing on labels, receipts, barcode labels, tags, air tickets, and the like.
[0002]
[Prior art]
Inkjet printers are commonly used for POS, or point-of-sale information management receipt prints in supermarkets, retail stores, and other businesses. A typical fixed printhead inkjet printer includes an array of printheads that are fixed with respect to the path of the print media. Each print head is staggered to achieve a full print width. For example, five print heads 10a to 10e are arranged alternately as shown in FIG. During printing, the print media 12 is pulled off the supply roll and advanced forward along the flow axis. This forward direction is indicated by an arrow F.
[0003]
As the print media 12 passes under the print heads 10 a-10 e, the print heads 10 a-10 e apply a swath of ink dots to the print media 12. After printing is completed, the printed portion moves forward and out of the printer, and is separated from the remaining print media.
[0004]
The print medium remaining in the printer has a large blank section that begins at the first print head 10a and ends at the "leading edge" L. In order to avoid wasteful use of the print medium, the leading edge L is retracted to the vicinity of the first print head 10a in the printer (the direction of retracting is indicated by an arrow R). By retreating in this way, the next printout can be started near the leading edge L of the print medium 12.
[0005]
[Problems to be solved by the invention]
When retracting the print media, the leading edge should not flutter. Typically, a vacuum hold down mechanism is used to control the leading edge while the print medium is being retracted. However, such a vacuum hold-down mechanism complicates the print media path device.
[0006]
Particularly when the print medium is retracted over a long distance, it takes time to retract the print medium. By retreating, printing of labels, receipts, etc. is delayed.
[0007]
Pulling the print media back to the supply roll during retraction can cause problems with the printer's print media back tensioning system. Also, the edge of the print medium may get caught during retraction. Accordingly, there is a possibility that the reliability of handling the print medium is lowered due to the backward movement.
[0008]
[Means for Solving the Problems]
According to one aspect of the invention, a printer includes a plurality of fixed printheads, a print media path, and a transfer roller that transfers ink from the printhead to a transfer zone on the print media path. Other aspects and advantages of the present invention will become apparent in the following detailed description when taken in conjunction with the accompanying drawings. In the following detailed description, the principles of the present invention will be described by way of example.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in the drawings, the present invention can be applied to an inkjet printer that prints a point-of-sale information management receipt. Little or no retraction is required to print on the receipt. Accordingly, the receipt can be printed at a higher speed while the handling reliability of the print medium is higher. Even if retraction is required, a vacuum hold-down mechanism or other mechanism that controls the leading edge of the print media is not required.
[0010]
Reference is now made to FIG. The figure shows an inkjet printer 110 that prints a point-of-sale information management receipt. The printer 110 includes a print medium path 112, a plurality of print heads 114, a transfer roller 116, a pressure roller 118, and a print medium path device. The print media path device includes a feed roller 120 that holds a print media supply roll, and pulls the print media out of the feed roller 120 and causes the print media to flow through the print head 114 (indicated by arrow F). And a pinch roller (print medium advance roller) 122 that is advanced forwardly.
[0011]
The print head 114 is disposed near the periphery of the transfer roller 116 and is stationary with respect to the rotation axis A of the transfer roller 116. The print head 114 may be a conventional inkjet print head. Although four print heads 114 are shown, the number of print heads 114 in the printer 110 is not limited thereto.
[0012]
The pressure roller 118 is movable in both directions indicated by an arrow P. The pressure roller 118 is moved between a first position (shown by a broken line) and a second position (shown by a solid line) by an actuator such as a servo-driven cam operating mechanism. In the first position, the pressure roller 118 is disposed at a distance from the transfer roller 116 and is not biased by the transfer roller 116, that is, is not engaged with the transfer roller 116 (retracted position).
[0013]
In the second position, the pressure roller 118 is biased by the transfer roller 116. Surrounding the contact surface between the transfer roller 116 and the pressure roller 118 is a transfer zone Z or “nib”. The pressure roller 118 may have an elastic surface that distorts during contact with the transfer roller 116. Due to this distortion, the area of the transfer zone Z increases.
[0014]
The pressure roller 118 may move and mesh when printing is started, and may move and not mesh when printing is completed.
[0015]
Further, referring to FIG. 3A, the transfer roller 116 includes a cylindrical core 116a surrounded by a metal sheath 116b. A plurality of wells 126 are patterned on the sheath 116b (see also (b) in the figure) and coated with a lining material 116c. The well 126 is disposed near the outer surface of the transfer roller 116. During printing, the print head 114 selectively fills the well 126 with ink drops.
[0016]
The receipt may be printed as follows. The pressure roller 118 is not engaged with the transfer roller 116, the transfer roller 116 is rotated at a constant angular speed by a DC servo motor or other type of motor (not shown), and the pinch roller 122 is moved from the feed roller 120. The print medium is pulled out and advanced in the flow direction F.
[0017]
The print head 114 begins depositing ink drops into the well 126. The print head 114 may be fired in a conventional manner. For example, a controller (not shown) receives swath data from the host and commands the printhead 114 to fire (ie, deposit ink drops) in response to the swath data. Since the transfer roller 116 is rotating, each row of wells 126 is filled with ink drops.
[0018]
Next, the pressure roller 118 is moved to the second position (shown by a solid line). In the second position, the pressure roller 118 is biased by the transfer roller 116, thereby causing the transfer roller 116 and the pressure roller 118 to rotate forward. The print medium is sandwiched between the two rollers 116 and 118.
[0019]
As transfer roller 116 continues to rotate, each row of wells 126 enters transfer zone Z and contacts the print medium. The ink drops in each row of these wells 126 are transferred to the print medium. All this happens so quickly that there is no time for the ink to dry on the transfer roller 116 before it is transferred to the print medium.
[0020]
After the text and image are transferred to the print medium (ie, after the receipt is printed), the pressure roller 118 is not engaged, and the pinch roller 122 advances the receipt and passes the cutting tool 124. The receipt may be cut using the cutting tool 124.
[0021]
Since the transfer of the ink to the print medium is performed along a straight line in the transfer zone Z, the cutting tool 124 may be disposed very close to the transfer zone Z. Thus, little or no retraction is required to prepare for the next printout.
[0022]
A vacuum hold-down mechanism for controlling the leading edge of the print medium is not required. This simplifies the design of the print media routing device.
[0023]
The printer 110 may have a small form factor in the direction of travel of the print medium. This is because the print head 114 surrounds the transfer roller 116. This becomes evident in contrast to the spaced-apart printheads 10a-10e of FIG.
[0024]
Referring now to FIG. 3b, exemplary dimensions for each well 126 are about 200 micrometers wide and about 45 micrometers deep. With these dimensions, each well 126 can hold several drops of ink 128. The wells 126 are spaced apart from each other to achieve a desired print density (eg, 600 dpi). The sidewall of the well 126 may be tapered so that the droplet 128 collects at the bottom of the well 126. Due to the surface tension, an ink meniscus is formed at the top of the well 126. During transfer, the ink drops 128 move cleanly from within the smoothly lined well 126 onto the print media. Virtually no ink remains behind.
[0025]
Reference is now made to FIG. This figure is a flowchart summarizing the printing method according to the present invention. The print medium is advanced (210) into the transfer zone, ink is collected from a plurality of fixed and staggered print heads (212), and the collected ink is transferred to the print medium in the transfer zone (214). ). After the text and image are transferred to the print medium, the printed portion is cut off (216). After the printed portion has been cut off, the print media may optionally be retracted (218) without controlling the leading edge of the print media. A feed roller 120 and a pinch roller 122 can be used as a device for performing the backward movement.
[0026]
The well 126 is not limited to a circular cell. Other well configurations may be used. For example, the well may have a cornered shape. Other well (or cell) configurations are disclosed in US application Ser. No. 09 / 571,647, incorporated herein by reference.
[0027]
There is no need to fix the printhead. For example, the print head may move in the direction of the rotation axis of the transfer roller.
[0028]
Although the printer has been described above with respect to printing receipts in the point-of-sale information management system, it is not so limited. For example, this printer may be used to print labels, barcode labels, tags, air tickets, and the like. In general, the printer may be used to print on cut print media, continuous print media (eg, print media on a supply roll), and the like.
[0029]
The printer includes a motor driving device and a motor control device not shown in FIG. The transfer roller, pressure roller, and pinch roller are all driven by a servo. The mechanism for moving the pressure roller between the first position and the second position may be implemented in a number of ways. For example, a motor / transmission may drive an actuator such as a cam or lever.
[0030]
The printer also includes a back tensioning mechanism for the print medium. This back tension applying mechanism is not shown in FIG.
[0031]
The printer includes a print control device. The print controller is not shown in FIG. The print controller receives swath data from the host and commands the motor controller to drive a roller, etc., to eject it to the print head.
[0032]
The present invention is not limited to the specific embodiments described above, but is construed according to the claims that follow.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a state of printing on a receipt using a conventional fixed print head.
FIG. 2 is a side view showing a schematic configuration of an ink jet printer according to the present invention.
3 is a drawing showing a well of a transfer roller forming a part of the ink jet printer of FIG. 2. FIG. 3A is an enlarged perspective view showing a part of the transfer roller in a broken view, and FIG. It is sectional drawing which shows the ink droplet in the well of a).
FIG. 4 is a flowchart illustrating a printing method according to the present invention.
[Explanation of symbols]
110 Printer 112 Print Media Path 114 Print Head 116 Transfer Roller 118 Pressure Roller 120 Feed Roller 122 Pinch Roller (Print Medium Advancement Roller)
124 Cutting tool Z Transfer zone

Claims (7)

Multiple printheads,
Print media path,
Comprising a patterned surface with a plurality of wells, the well may have a trapezoidal cross-section as the inner wall of the well is inclined toward the inner wall facing toward the bottom surface, the well, the plurality of print heads And a transfer roller for collecting the ink from the transfer path and transferring the ink to the transfer zone of the path.   2. The pressure roller according to claim 1, further comprising a pressure roller, wherein the transfer zone is defined by the transfer roller and the pressure roller when the pressure roller is biased by the transfer roller. The printer described.   The pressure roller is movable between a first position and a second position, is not biased by the transfer roller when in the first position, and is in the second position. The printer according to claim 2, wherein the printer is sometimes biased by the transfer roller.   The printer of claim 1, further comprising print media advance rollers on opposite sides of the transfer zone. Multiple printheads,
Print media path,
A surface patterned with a plurality of wells, the wells having a trapezoidal cross section such that the inner walls of the wells are inclined toward the opposing inner walls toward the bottom surface, the wells having the plurality of printheads; A transfer roller for collecting ink from the transfer path and transferring the ink to the transfer zone of the path;
And a device for retracting the print medium without controlling the leading edge of the print medium . A plurality of wells having a patterned surface, the wells having a trapezoidal cross section such that the inner walls of the wells are inclined toward the opposing inner walls as they move toward the bottom surface, the wells having the plurality of printheads; A transfer roller adapted to collect ink from and transfer the ink to a transfer zone on the print media path;
A plurality of print heads disposed around the transfer roller;
A pressure roller Ru movable der respect to the transfer roller, defining a moving pen with the transfer roller when said pressure roller is urged to the transfer roller, the outer surface is configured deformable A pressure roller and a printer. The pressure roller is movable between a first position and a second position, is not biased by the transfer roller when in the first position, and is in the second position. The printer according to claim 6, which is sometimes biased by the transfer roller.

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