Printing apparatus and printing method

Abstract

The present invention provides a printing apparatus and method capable of printing an image in a rear end area of a print medium. A sheet is transported by a transport roller and pinch rollers situated upstream of a print head with respect to the transport direction, and by a discharge roller and spurs situated downstream of the print head. After the sheet has left the transport roller and the pinch rollers, it is transported by the discharge roller and spurs. The sheet is printed with a test pattern for detecting a difference between a transport amount appearing before the sheet leaves the transport roller and pinch rollers and a transport amount appearing when the sheet leaves them. Based on a correction value set according to a printed result of the test pattern, the transport amount used when the sheet leaves the transport roller and pinch rollers is corrected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a printing apparatus in a first embodiment of this invention;

FIG. 2 is a perspective view showing a mechanism in the printing apparatus of FIG. 1;

FIG. 3 is a cross-sectional view of the printing apparatus of FIG. 1;

FIG. 4 is a block configuration diagram of a control system in the printing apparatus of FIG. 1;

FIG. 5 is an explanatory diagram showing an example of a printed test pattern in the first embodiment of this invention;

FIG. 6A is an explanatory diagram showing first dots in the test pattern of FIG. 5 and FIG. 6B is an explanatory diagram showing second dots in the test pattern of FIG. 5;

FIGS. 7A and 7B are explanatory diagrams showing other printed test patterns in FIG. 5;

FIG. 8 is an explanatory diagram showing an example of a printed test pattern in a second embodiment of this invention;

FIG. 9 is an explanatory diagram showing an example of a printed test pattern in a third embodiment of this invention;

FIG. 10 is an explanatory diagram showing a construction of a transport amount sensor in a fourth embodiment of this invention;

FIG. 11 is an explanatory diagram showing an example of a printed test pattern in a fifth embodiment of this invention, and

FIG. 12 is a flow chart showing a method of correcting a transport amount in the fifth embodiment of this invention.

Claims

1. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;printing means for printing on the print medium a test pattern used to detect a difference between a transport amount in a first transporting operation and a transport amount in a second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation transporting the print medium in which a transporting state is switched from a transporting state of the first transporting operation to a transporting state transporting the print medium not by the first transport means but by the second transport means; andcorrection means for correcting the transport amount in the second transporting operation based on a printed result of the test pattern.

2. A printing apparatus according to claim 1, wherein the test pattern has a plurality of blocks including a first test pattern portion printed before the second transporting operation and a second test pattern portion printed after the second transporting operation; wherein the plurality of blocks include blocks that have different positional relations between the first test pattern portion and the second test pattern portion in the transport direction.

3. A printing apparatus according to claim 2, wherein the plurality of blocks include blocks that have different transport amount of the print medium after the first test pattern portion has been printed until the second test pattern portion begins to be printed.

4. A printing apparatus according to claim 2, further comprising a sensor for measuring print densities of the plurality of blocks.

5. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;printing means for printing on the print medium a test pattern used to detect a difference between a transport amount in a first transporting operation and a transport amount in a second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation transporting the print medium not by the first transport means but by the second transport means; andcorrection means for correcting the transport amount in the second transporting operation based on a printed result of the test pattern.

6. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;detecting means for detecting a transport amount in a first transporting operation and a transport amount in a second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation transporting the print medium in which a transporting state is switched from a transporting state of the first transporting operation to a transporting state transporting the print medium not by the first transport means but by the second transport means; andcorrection means for correcting the transport amount in the second transporting operation based on a result of detection by the detection means.

7. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;detection means for detecting a transport amount in a first transporting operation and a transport amount in a second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation transporting the print medium not by the first transport means but by the second transport means; andcorrection means for correcting the transport amount in the second transporting operation based on a result of detection by the detection means.

8. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;printing means for printing on the print medium a test pattern used to detect a difference between transport amounts of the print medium in a first transporting operation and a second transporting operation or a difference between transport amounts of the print medium in the first transporting operation and a third transporting operation; andcorrection means for correcting the transport amount in the second transporting operation or the transport amount in the third transporting operation based on a printed result of the test pattern;wherein the first transporting operation is a transporting operation for transporting the print medium by the first transport means and the second transport means;wherein the third transporting operation is a transporting operation for transporting the print medium not by the first transport means but by the second transport means;wherein the second transporting operation is a transporting operation interposed between the first transporting operation and the third transporting operation.

9. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;detection means for detecting any one of transport amounts of the print medium in a first transporting operation and a second transporting operation, transport amounts of the print medium in the first transporting operation and a third transporting operation, or transport amounts of the print medium in the first transporting operation, the second transporting operation and the third transporting operation; andcorrection means for correcting the transport amount in the second transporting operation or the third transporting operation based on a result of detection by the detection means;wherein the first transporting operation is a transporting operation for transporting the print medium by the first transport means and the second transport means;wherein the third transporting operation is a transporting operation for transporting the print medium not by the first transport means but by the second transport means;wherein the second transporting operation is a transporting operation interposed between the first transporting operation and the third transporting operation.

10. A printing apparatus for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing apparatus comprising: first transport means for transporting the print medium, the first transport means being installed upstream of the print head with respect to the transport direction;second transport means for transporting the print medium, the second transport means being installed downstream of the print head with respect to the transport direction;correction means for correcting a transport amount in a second transporting operation based on a correction value, the correction value being set according to a difference between a transport amount in a first transporting operation and the transport amount in the second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation including a transporting state transporting the print medium not by the first transport means but by the second transport means.

11. A printing method for printing an image on a print medium by repetitively performing a scan operation that scans a print head in a scan direction and a transport operation that transports the print medium in a transport direction crossing the scan direction, the printing method comprising the steps of: transporting the print medium by a first transport means installed upstream of the print head with respect to the transport direction or by a second transport means installed downstream of the print head with respect to the transport direction; andcorrecting a transport amount in a second transporting operation based on a correction value, the correction value being set according to a difference between a transport amount in a first transporting operation and the transport amount in the second transporting operation, the first transporting operation transporting the print medium by the first transport means and the second transport means, the second transporting operation including a transporting state transporting the print medium not by the first transport means but by the second transport means.