KR20040110501A - Printer having a detecting function of skew and control method thereof - Google Patents

Abstract

PURPOSE: A printer and a method for controlling the same are provided to improve printing quality by detecting skew when picking up papers and aligning front ends of papers by adaptively controlling a pickup roller. CONSTITUTION: An ink jet printer(100) includes an operating panel(110), a storage section(120), an edge detecting section(130), a skew calculating section(140), a compensation section(150), a motor driving section(160), a head driving section(170) and a control section(190). The operating panel(110) has an input part having plural functional keys and a display section for displaying an operational state of the ink jet printer(100). The storage section(120) has a non-volatile memory part for storing control programs and a volatile memory part for temporarily storing data.

Description

Printer having a detecting function of skew and control method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer having a skew detection function and a control method thereof, and more particularly, to a printer capable of detecting and correcting a skew phenomenon in which paper is fed at an angle when the paper loaded in the paper cassette is fed. It relates to a control method.

A printer is generally classified into an inkjet printer and a laser printer according to a printing method of a printing engine. Such a printer is provided with a paper feeding device for conveying paper loaded in a paper cassette into the printer body.

1 is a cross-sectional view schematically showing a conventional inkjet printer.

Referring to FIG. 1, an inkjet printer includes a paper feed cassette 10 loaded with recording paper P, a pickup roller 20 for supplying recording paper P loaded in the paper cassette 10 into the printer, and a pickup. The paper transport unit 30 for transporting the recording paper P picked up by the roller 20, the printing unit 40 for performing a printing operation on the recording paper P transported by the paper transport unit 30, and printing And a discharge apparatus 50 for discharging the completed recording paper P out of the apparatus.

Looking at the operation of the inkjet printer having the above configuration, the recording paper (P) loaded in the paper feed cassette 10 is picked up by the pickup roller 20 is supplied to the paper transport unit (30). The recording paper P supplied to the paper conveying unit 30 is conveyed to the printing unit 40 along the paper conveying path set by the rotation of the feed roller 31 and the friction roller 32.

When the recording paper P conveyed by the paper conveying unit 30 enters the printing unit 40, the printing unit 40 has left the carriage equipped with an ink cartridge having a nozzle for ejecting ink. The printing job is performed by discharging ink onto the recording paper P which is transferred while moving to the right. The paper printed by the printing unit 40 is discharged to the outside through the discharge device (50).

The printing operation is performed through a series of processes as described above. When picking up the recording paper P loaded in the paper cassette 10 by the pickup roller 20, a skew phenomenon occurs in which the recording paper P is picked up at an angle. . When the paper picked up obliquely by the pickup roller 20 enters the printing unit 40 as it is, the printing quality is deteriorated because the printing operation is performed in a state where the leading end of the paper is not aligned.

Conventionally, in order to correct the skew phenomenon, the recording paper P picked up by the pick-up roller 20 is set to a preset correction amount in accordance with the point of time between the feed roller 31 and the friction roller 32. The driving of the feed roller 31 and the pickup roller 20 was controlled. In detail, the feed roller 31 is rotated by the preset correction amount so that the recording paper P is no longer fed in the paper feed direction, so that the pickup roller 20 is rotated by the set amount of rotation. The tip of P) was aligned. After a certain time, the feed roller 31 is rotated forward so that the recording paper P is conveyed.

However, when controlling the driving of the feed roller 31 and the pickup roller 20 with a preset correction amount regardless of the amount of skew generated at the time of picking up the paper as in the prior art, it is impossible to accurately align the leading edge of the recording paper P. A problem occurs. This is because the amount of skew generated at the time of paper pickup may appear different depending on the material or thickness of the recording paper P. In addition, if the skew amount generated at the time of picking up the paper is large due to the wear of the feed roller 31 or the pick-up roller 20 or the slippage of the paper, the skew caused at the time of picking up the paper cannot be corrected with the first set amount. do.

The technical problem to be achieved by the present invention is to detect the amount of skew generated during paper pick-up, and adaptively control the driving of the feed roller and the pick-up roller according to the detected skew amount to align the leading edge of the paper to improve the print quality. The present invention provides a printer having a skew detection function and a control method thereof.

1 is a cross-sectional view schematically showing a conventional inkjet printer,

2 is a block diagram of an inkjet printer having a skew detection function according to a preferred embodiment of the present invention, and

FIG. 3 is a view for explaining a control method of the inkjet printer shown in FIG. 2.

Explanation of symbols on the main parts of the drawings

100: inkjet printer 120: storage unit

130: edge detection unit 140: skew amount calculation unit

150: compensation unit 160: motor driving unit

170: head driving unit 190: control unit

In order to solve the above technical problem, a printer having a skew detection function according to the present invention includes a feed roller for transporting a recording paper picked up by a pickup roller, and a tip of the recording paper transported by the feed roller. And an edge detector for detecting left and right edges at each of the ends, a skew amount calculator for calculating the degree of twist of the recording paper using the edge information detected by the edge detector, and a skew amount corresponding to the skew amount. And control the skew amount calculation unit to calculate the skew amount based on the detected edge information when the edge detection result signals for the front end and the end of the recording paper are received from the storage unit and the edge detection unit storing the correction value. The driving of the pickup roller and the feed roller in accordance with the correction value stored in the storage unit in response to the skew amount And a control unit for processing to correct the amount of skew generated at the time of picking up the recording paper.

Preferably, an error calculating unit for calculating a skew amount error that is a difference between the skew amount and the target skew amount calculated by the skew amount calculating unit, and a proportional, integral, and derivative operation to compensate for the calculated skew amount error. Further comprising a compensation unit having a PID controller for performing the.

The controller processes a skew phenomenon generated when the recording paper is picked up according to the correction value stored in the storage unit in response to the skew amount compensated by the compensation unit.

On the other hand, in order to solve the above technical problem, the control method of the printer with a skew detection function according to the present invention, the left side of each of the front end and the end of the recording paper picked up by the pickup roller and conveyed by the feed roller And a step of detecting a right edge, calculating a skew amount indicating a degree of twist of the recording paper by using the edge information detected by the engine detection sensor, and a previously stored correction value corresponding to the calculated skew amount. And controlling the driving of the pick-up roller and the feed roller to correct a skew phenomenon generated when the recording paper is picked up.

Preferably, the method further includes calculating a skew amount error, which is a difference between the calculated skew amount and a target skew amount, and outputting the compensated skew amount by performing compensation for the associated skew amount error.

The skew amount correcting step corrects the skew phenomenon generated when the recording paper is picked up by controlling the driving of the pickup roller and the feed roller according to a pre-stored correction value corresponding to the compensated skew amount.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a block diagram of an inkjet printer according to a preferred embodiment of the present invention.

Referring to FIG. 2, the inkjet printer 100 includes an operating panel 110, a storage unit 120, an edge detector 130, a skew amount calculator 140, a compensator 150, and a motor driver. 160, a head driving unit 170 and a control unit 190 are provided.

The operation panel 110 is an operating state of the inkjet printer 100 under the control of an input unit (not shown) and a controller 190 provided with a plurality of function keys for selecting or setting various functions supported by the inkjet printer 100. It is composed of a display unit (not shown) for displaying the.

The storage unit 120 may include a nonvolatile memory such as a ROM in which various control programs necessary for implementing the functions of the inkjet printer 100 are stored, and a DRAM such as temporarily storing data generated during program execution of the controller 190. It has a volatile memory. In the storage unit 120 according to the present embodiment, correction value information corresponding to an amount of skew indicating how much the paper is picked up at an angle by the pickup roller is recorded in the form of a look-up table (LUT). . Here, the correction value is a control value for controlling the driving of the feed roller 31 and the pickup roller 20 to correct the amount of skew generated at the time of picking up the paper.

The edge detection unit 130 detects left and right edges with respect to the front end and the end of the recording paper P, respectively. The edge detector 130 is composed of a light emitting unit for irradiating predetermined light and a light receiving unit for receiving the transmitted light. The edge detection unit 130 detects the light level of the recording paper P, and thus, the left side of each of the front end and end of the recording paper P And the right edge is detected.

In more detail, the edge detector 130 irradiates predetermined light onto the recording paper P, receives light reflected from the recording paper P, and detects the light level of the recording paper P. That is, the edge detection unit 130 uses the difference between the light level of the portion where the recording paper P is located and the light level of the portion where the recording paper P is not located, to the left and the ends of each of the front end and the end of the recording paper P. Detect right edge The edge detector 130 transmits the left and right edge detection result signals to the controller 190 for each of the front end and the end of the recording paper P. FIG. The edge detection unit 130 according to the present embodiment is an edge detection sensor for detecting the edge of the recording paper P. The edge detection unit 130 includes a separate edge detection sensor, or is printed to correct vertical / horizontal alignment due to printing deviation. The edge of the recording paper P may be detected by using an alignment sensor provided at one side of a carriage on which the head is mounted and detecting a printing pattern.

The skew amount calculation unit 140 uses recording paper using information corresponding to the left and right edges of each of the front end and the end of the recording paper P detected by the edge detector 130 under the control of the controller 190. The amount of skew indicating the twist information of (P) is calculated. Herein, the information corresponding to the left and right edges of each of the front end and the end of the recording paper P means the positional information of the carriage when the respective left and right edges are detected. Accordingly, the skew amount calculation unit 140 calculates the skew amount based on the positional information of the carriage corresponding to each of the left and right edges.

The compensator 150 calculates a skew amount error that is a difference between the current skew amount and the target skew amount under the control of the controller 190, and compensates for the calculated skew amount error. The compensation unit 150 calculates the skew amount error, which is a difference between the skew amount calculated by the skew amount calculating unit 140 and the target skew amount, and the skew amount error calculated by the error calculating unit 152. A PID (Proportional, Integral, Differential) controller 154 that performs proportional-integral-derived to compensate. The compensator 150 transmits the compensated skew amount information to the controller 190. Here, the target skew amount means a value where the skew amount value is zero (0).

The motor driving unit 160 carries a carriage feed motor for transporting a carriage equipped with a line feed motor and a print head 180 for driving the pickup roller and the feed roller under the control of the controller 190. To drive.

The head driver 170 drives the print head 180 to eject ink through a nozzle provided in the print head 180 to record an image on the recording paper P. FIG. The print head 180 is driven by the head driver 170 as a recording head in which a plurality of nozzles are arranged.

The controller 190 controls the overall operation of the inkjet printer 100 according to a control program stored in the storage 120. In the present embodiment, only the operation of the control unit 190 related to the skew amount detection and skew amount correction generated when picking up the paper will be described.

The controller 190 controls the skew amount calculating unit 140 to calculate a skew amount based on the edge detection result signal when the edge detection result signal is received from the edge detection unit 130. When the skew amount is calculated by the skew amount calculation unit 140, the controller 190 reads a correction value corresponding to the skew amount calculated from the storage unit 120. The controller 190 controls the motor driving unit 160 to drive the pickup roller and the transfer roller by the read-out correction value. The feed roller 31 rotates in a predetermined number of times or a predetermined time in response to the correction value under the control of the motor driver 160, and the pickup roller 20 is rotated a predetermined number of times or a predetermined time according to the driving of the motor driver 160. Tell.

In addition, the controller 190 controls the compensator 150 to compensate for the error in consideration of the occurrence of an error in the amount of skew calculated by the skew amount calculator 140. When the compensation for the skew amount error is completed by the compensator 150, the controller 190 controls the driving of the transfer roller and the pickup roller with a correction value corresponding to the skew amount compensated by the compensator 150. That is, the controller 190 reads a correction value corresponding to the amount of skew compensated by the compensation unit 150 from the storage unit 120, and the motor driving unit 160 drives the feed roller and the pickup roller by the read correction value. ).

Hereinafter, a method of controlling an inkjet printer having a skew detection function according to an exemplary embodiment of the present invention will be described with reference to FIG. 3.

First, when the recording paper loaded in the paper feed cassette is picked up by the pickup roller in response to the printing command, the picked recording paper P is transported along the set paper transport path (S200). When the recording paper P conveyed by the feed roller enters the printing area, the edge detection unit 130 determines the light level of the portion where the recording paper P is located and the optical level of the portion where the recording paper P is not located. By using the difference, the left edge and the right edge of each of the front end and the end of the recording paper P are detected (S210).

When the edge detection result signal is received from the edge detector 130, the controller 190 supplies information corresponding to the left edge and the right edge of each of the front end and the end of the recording paper P detected by the edge detector 130. The skew amount calculating unit is controlled to calculate the skew amount on the basis of the step (S220). The skew amount calculating unit 140 calculates the skew amount using the position information of the carriage corresponding to the left and right edge information detected by the edge detector 130 under the control of the controller 190.

When the skew amount generated when the paper is picked up by the skew amount calculation unit 140 is calculated, the controller 190 controls the compensator to compensate for an error with respect to the calculated skew amount. The error calculator 152 calculates a skew amount error that is a difference between the skew amount calculated by the skew amount calculator 140 and the target skew amount under the control of the controller 190 (S230). When the skew amount error is calculated by the error calculator 152, the PID controller 154 calculates the compensated skew amount by performing proportional-integral-derivation using the skew amount error (S240).

When the amount of skew compensated by the PID controller 154 is calculated, the controller 190 reads a correction value corresponding to the amount of skew compensated by the compensation unit 150 from the storage unit 120, and the correction value corresponds to the read correction value. Correspondingly, the motor driving unit 160 is controlled to drive the transfer roller and the pickup roller (S250).

Therefore, the tip of the recording paper P can be always aligned, and the print quality can be improved because the tip of the recording paper P is transferred to the printing apparatus in an aligned state.

Although the present invention has been described in detail through the representative embodiments, those skilled in the art to which the present invention pertains can make various modifications without departing from the scope of the present invention. Will understand. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described so far, according to the printer with the skew detection function and the control method thereof according to the present invention, each time a print job is performed, the amount of skew generated when picking up the paper is detected, By adaptively selecting and correcting a large number of correction values, it is possible to always align the leading edge of the recording paper, thereby improving print quality.

Claims (6)

A feed roller for transporting the recording paper picked up by the pick-up roller; An edge detection unit for detecting left and right edges of each of the front end and the end of the recording paper conveyed by the feed roller; A skew amount calculating section for calculating a degree of distortion of the recording paper by using the edge information detected by the edge detecting unit; A storage unit for storing a correction value corresponding to the amount of skew; And When the edge detection result signals for the front end and the end of the recording paper are received from the edge detection unit, the skew amount calculation unit is controlled to calculate the skew amount based on the detected edge information, and corresponding to the calculated skew amount. And a control unit for controlling driving of the pickup roller and the feed roller according to the correction values stored in the storage unit so that the amount of skew generated when picking up the recording paper is corrected. The method of claim 1, An error calculating unit for calculating a skew amount error that is a difference between the skew amount and a target skew amount calculated by the skew amount calculating unit, and a PID for performing proportional, integral, and derivative operations to compensate the calculated skew amount error. A printer having a skew detection function, further comprising a compensation unit having a controller. The method of claim 2, The controller is configured to process a skew phenomenon generated when the recording paper is picked up according to a correction value stored in the storage unit in response to the amount of skew compensated by the compensation unit. . Detecting left and right edges of each of the front end and the end of the recording paper picked up by the pickup roller and conveyed by the transfer roller; Calculating a skew amount indicating a degree of twist of the recording paper by using the edge information detected by the engine detection sensor; And And controlling the driving of the pick-up roller and the feed roller according to a pre-stored correction value corresponding to the calculated amount of skew to correct a skew phenomenon generated at the time of picking up the recording paper. How to control one printer. The method of claim 4, wherein Calculating a skew amount error that is a difference between the calculated skew amount and a target skew amount; And And outputting a compensated skew amount by performing compensation for the associated skew amount error. The method of claim 5, In the skew amount correcting step, the skew detection function corrects the skew phenomenon generated when picking up the recording paper by controlling the driving of the pickup roller and the feed roller according to the pre-stored correction value corresponding to the compensated skew amount. Control method of the printer provided with.