JPH05338333A - Method of detecting sheet end of printer - Google Patents

Abstract

PURPOSE:To provide a detecting method of a sheet end of a printer which can prevent the forms from scattering and detect precisely a position of the end of the sheet by a simple method. CONSTITUTION:In a detecting method of an end of a sheet of a printer scanning and detecting the end of the sheet by a detecting device 12 while running a carriage 3 along a platen 2, on which a printing head 10, which is made detachable freely to the platen 2, and a detecting device 12 detecting the end of the sheet in the direction meeting at right angles with a running direction of the form 11 are mounted, the device is constituted so that the end of the sheet is scanned and detected under a state wherein the sheet 11 is made to pinch and held between the platen 2 and printing head 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper edge detection method for a printer used as an output device such as a computer and a word processor, and more particularly, a thermal head is used as a print head, and an image such as a predetermined character is generated by the heat generated by the thermal head. The present invention relates to a paper edge detection method suitable for a thermal transfer printer that prints on a recording medium such as paper.

[0002]

2. Description of the Related Art Generally, a recording medium such as paper and an ink ribbon coated with a heat-melting ink are supported in front of a platen, and a thermal head having a plurality of heating elements arranged on the platen together with a carriage. Thermal transfer for printing desired characters and other images on a recording medium such as paper by selectively heating the heating elements arranged in the thermal head based on print information while reciprocating along Printers are widely used as output devices for computers, word processors and the like because of their high printing quality, low noise, low cost, and ease of maintenance.

In such a thermal transfer printer, when an image such as a desired character is printed on a recording medium such as a paper, an image such as a desired character is printed at a predetermined position on the paper. Therefore, at least the position of the sheet edge in the direction orthogonal to the sheet traveling direction is detected.

Further, in order to detect the edge of the sheet, the sheet is supplied in a head-up state in which the platen and the thermal head are separated from each other, and in this head-up state, the carriage is reciprocally moved and scanned to scan the carriage. The edge of the sheet is detected by a detection unit such as a photo sensor provided.

[0005]

However, in the above-described method for detecting the sheet edge of the conventional printer, the carriage is reciprocated while the sheet is fed between the platen and the head-up thermal head. Scanning is performed, and the edge of the sheet is detected by the detection means provided on the carriage. Therefore, the vibration caused by the traveling of the carriage is transmitted to the sheet, and the sheet vibrates to cause the sheet to flap.
There is a problem in that the position of the sheet changes during the reciprocating movement of the carriage, and the position of the edge of the sheet cannot be accurately detected. Further, when the carriage is moved, there is a problem that the carriage and the edge portion of the sheet are caught and the sheet is deformed and printing cannot be performed.

The present invention has been made in view of these points, and overcomes the above-mentioned problems of the conventional ones.
It is an object of the present invention to provide a paper edge detection method for a printer, which can prevent the paper from flapping and can accurately detect the paper edge position by a simple method.

[0007]

In order to achieve the above-mentioned object, a method of detecting a sheet edge of a printer according to the present invention includes a print head that is movable toward and away from a platen and a direction orthogonal to a sheet traveling direction. In a paper edge detection method for a printer, in which a carriage equipped with a detection means for detecting the paper edge is scanned along the platen while scanning the paper edge by the detection means, the platen and the print head are It is characterized in that the sheet edge is scanned and detected while the sheet is sandwiched between them.

[0008]

According to the paper edge detection method for a printer of the present invention having the above-described structure, when the paper edge is detected, the carriage is run in a head-down state in which the paper is sandwiched between the platen and the print head. By doing so, the edge of the sheet can be detected by the detection means provided in the carriage, so that the sheet can be prevented from flapping while the carriage is running, and the edge of the sheet can be accurately detected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view showing the structure of the main part of an embodiment of a printer to which the paper edge detection method for a printer of the present invention is applied, and FIG. 2 is a side view of the main part.

As shown in FIG. 1, the printer 1 according to the present embodiment.
1, a platen 2 having a substantially flat plate shape is fixedly arranged, and a carriage 3 is arranged on the front side of the platen 2 so as to be reciprocally movable in parallel with the platen. Below the carriage 3, drive means 4 for driving the carriage 3 is provided. That is, the carriage 3
Fixed pulley 5 provided at a position outside the moving range of
An appropriate driving force transmission means 7 such as an endless belt is wound between the movable pulley 6 and the movable side pulley 6, and the carriage 3 is fixed to a predetermined position of the driving force transmission means 7. The fixed pulley 5 is rotationally driven by a step motor 9 which is rotated by a command from the control means 8.

A thermal head 10 as a print head is arranged on the carriage 3 so as to come in contact with and separate from the platen 2. Further, at both ends of the surface of the carriage 3 facing the platen 2, the paper 11 which is a recording medium is provided.
Appropriate detecting means 12 such as photosensors for detecting the left and right sheet ends in the drawing in a direction orthogonal to the traveling direction of the sheet are respectively provided. The detection means 12 arranged on the left side of the drawing is a first detection means 12a for detecting the left end of the paper 11,
The detection means 12 arranged on the right side of the drawing is a second detection means 12b for detecting the right edge of the paper 11.

A step motor 9 called a stepping motor, a stepper, a pulse motor or the like is used to drive the pulley 5. The step motor 9 corresponds to an electric pulse of an input signal to this pulse. This is because the digital control for converting into the mechanical displacement is easy, it is possible to cope with frequent start-stop, the self-start frequency is provided, and the time for the carriage 3 to reach a predetermined speed can be shortened.

Further, as shown in FIG. 2, the paper 11 is supplied to the platen 2 and the thermal head 10 by an appropriate paper guide 13.
The sheet is fed by a sheet feeding device (not shown) between the sheet and the sheet.

Next, the printer 1 having the above-mentioned configuration
The paper edge detection method for the printer of this embodiment, which is applied to the above, will be described with reference to FIGS.

FIG. 3 is a flow chart showing the paper edge detection method of the printer according to the present invention, FIG. 4 is an explanatory view showing the movement of the carriage to the home position, and a to c of FIG. 5 are at the home position. FIG. 6 is an explanatory diagram showing a positional relationship between a detection unit of a carriage and a sheet.

First, at step ST10, the step motor 9 is operated based on a control command from an appropriate control means 8 to move the carriage 3 to a predetermined initial position (home position), as shown in FIG. Then, it is moved to the left as indicated by the broken line in the figure, and the process proceeds to the next step ST11.

Next, in step ST11, the first detecting means 1 of the carriage 3 moved to the home position.
Whether the position of the sheet 11 with respect to 2a is in any of a to c in FIG. 5 is determined by whether the first detection unit 12a is ON. That is, as shown in FIGS. 5A and 5B, when the left end of the sheet 11 is on the right side of the first detecting unit 12a and there is no sheet, it is determined as NO, and as shown in FIG. When the left end of the sheet 12 is on the left side of the first detecting means 12a and the sheet is present, YES is determined. If the determination in step ST11 is NO (no paper), the process proceeds to the next step ST12 and step ST12.
, The carriage 3 is moved rightward in the figure by a predetermined number of steps of the step motor 9, that is, one step in the present embodiment, and the process proceeds to the next step ST13 and step ST13.
At 13, it is again determined whether the first detection means 12a is ON (paper is present). When the determination in step ST13 is NO (no paper is present), the carriage 3 is set to 1 until the determination in step ST13 is YES (paper is present).
Move to the right step by step. If the determination in step ST13 is YES (there is paper), the process proceeds to the next step ST14.

Next, in step ST14, the movement of the carriage 3 to the right is stopped, and the process proceeds to the next step ST15. In step ST15, the carriage 3 is moved by the predetermined number of steps of the step motor 9, in the present embodiment. After moving 10 steps to the left, which is the reverse direction, the carriage 3 is stopped and the process proceeds to the next step ST16. In this step ST16, the thermal head 10 is moved toward the platen 2 (head down),
The platen 2 is attached to the paper 11 via an ink ribbon (not shown).
And the thermal head 10, and the process proceeds to the next step ST17.

Next, in step ST17, the carriage 3 is moved rightward in the figure by a predetermined number of steps of the step motor 9, that is, one step in the present embodiment, and the process proceeds to the next step ST18.

Next, in step ST18, it is determined whether or not the first detecting means 12a is ON (paper is present). If the determination in step ST18 is NO (paper is absent), the process returns to step ST17 and step ST18. The carriage 3 is moved to the right one step at a time until the determination is YES (there is paper). Then, the determination in step ST18 is YE.
If S (there is paper), the next step ST
The process proceeds to step 19, and the position is stored in the control means 8 as the position of the left end of the sheet 11, and the process proceeds to step ST20.

Next, in step ST20, the carriage 3 is moved rightward in the figure by a predetermined number of steps of the step motor 9, that is, one step in the present embodiment, and the process proceeds to the next step ST21 and the second detecting means 12b. It is determined whether or not is ON (there is paper). If the determination in step ST21 is NO (no paper), the process returns to step ST20, and the carriage 3 is moved rightward step by step until the determination in step ST21 is YES (paper is present). If the determination in step ST21 is YES (there is paper), the process proceeds to the next step ST22, and the control unit 8 sets the position as the right end position of the paper 11.
To memorize and end.

Further, the determination in step ST11 is YES.
In the case of (with paper), the process proceeds to the next step ST23, the thermal head 10 is moved (head down) toward the platen 2, and the paper 11 is separated from the platen 2 and the thermal head 10 via an ink ribbon (not shown). The sheet 11 and the sheet 11
The position of the left end of the sheet 11 is stored in the control means 8 and then the process proceeds from step ST20 to step ST22 to store the position of the right end of the sheet 11 in the control means 8 and the process ends.

As described above, according to the paper edge detection method for the printer of this embodiment, the left and right edges of the paper 11 are detected in the head-down state in which the paper 11 is sandwiched between the platen 2 and the thermal head 10. Therefore, when the paper edge is detected, the paper 11 flickers and an accurate paper edge cannot be detected, and the carriage 3 and the paper 1 are not detected.
It is possible to reliably remove the inconvenience that the edge of the sheet 1 is caught and the paper 11 is deformed to make printing impossible, the left and right edges of the paper 11 are surely recognized, and the printing quality can be improved.

The present invention is not limited to the above embodiment, and for example, after detecting the position of the left edge of the paper 11, the thermal head 10 is temporarily moved up and the carriage 3 is moved to the right. The second detecting means 12 is moved.
If b is turned on, the carriage 3 is stopped from moving to the right and moved to the left by a predetermined step, and then the thermal head 10 is headed down again. In this state, the carriage 3 is moved to the right. The procedure of moving the sheet 11 to detect the position of the right end of the sheet 11 may be used, and can be changed as necessary.

[0026]

As described above, according to the paper edge detecting method of the printer of the present invention, the paper edge in the direction orthogonal to the running direction of the paper can be surely detected, so that the predetermined print position can be detected. This has an extremely excellent effect that the accuracy of the actual print position can be made extremely accurate and the print quality can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a main part of an embodiment of a printer to which a paper edge detection method for a printer according to the present invention is applied.

FIG. 2 is a side view showing a configuration of a main part of an embodiment of a printer to which a paper edge detection method for a printer according to the present invention is applied.

FIG. 3 is a flowchart showing a paper edge detection method for a printer according to the present invention.

FIG. 4 is an explanatory diagram showing movement of a carriage to a home position.

5A to 5C are explanatory views showing the positional relationship between the detection unit of the carriage at the home position and the sheet.

[Explanation of symbols]

 2 platen 3 carriage 8 control means 9 step motor 10 thermal head 11 paper 12a first detection means 12b second detection means

Claims (1)

[Claims] 1. A carriage equipped with a print head which can be brought into and out of contact with a platen and a detection means for detecting a sheet edge in a direction orthogonal to the sheet traveling direction is caused to travel along the platen. Meanwhile, in the paper edge detection method for a printer in which the detection means scans and detects the paper edge, the paper edge is scanned and detected while the paper is sandwiched between the platen and the print head. Paper edge detection method.