JPH0632019A - Printer platen gap adjustment method - Google Patents

Abstract

PURPOSE:To prevent a trouble such as paper jam due to a page feed operation by widening a platen gap at the time of receiving a page feed signal more than that in a printing operation to perform the page feed. CONSTITUTION:When a signal from a host computer is judged to be a page feed signal, a print head is caused to retreat from a platen in step ST4 and a platen gap is made wider than that at the time of a printing operation. Then, a page feed operation is performed in step ST5 and the cuing of the next page is effected. Further, before the printing operation is started in step 6, the print head is advanced to the platen so that the platen gap is restored to that at the time of the printing operation. Subsequently, the printing operation of the next page is executed in step ST2 and said step is executed thereafter until printing ends. As a result, the printing operation can be performed while the optimum platen gap is maintained, and paper jam, etc., due to a page feed operation can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, and more particularly to a method for adjusting a platen gap between a print head and a platen of a wire type dot matrix printer.

[0002]

2. Description of the Related Art In recent years, printers of various printing systems such as thermal printers, laser printers and ink jet printers have been developed and used for various purposes. However, a wire type dot matrix printer is still widely used as a printer as an output device of a computer. The reason is that the wire-type dot matrix printer has a feature that it can print on various types of paper as well as copying machine paper, and has an excellent function that cannot be supported by the other types of printer devices described above. This is because Such a wire type dot matrix printer is used not only as an output device of a computer but also in many applications.

FIG. 3 shows an outline of a printing mechanism of a conventional wire type dot matrix printer. In this type of printer, the print paper 3 and the ink ribbon 4 are sandwiched between the nose 1a of the print head 1 and the platen 2, and a plurality of print wires held inside the nose 1a are used for external printing. Printing is performed by striking the surface of the ribbon and transferring the ink impregnated in the ink ribbon 4 to the surface of the paper 3 based on an image (printing) signal from an apparatus such as a host computer.

Normally, the printing paper 3 is a single paper and the paper thickness is 0.
When it is about 08 mm, the clearance between the platen surface and the tip of the print head 1a (so-called platen gap) G
Is controlled to an average of around 0.3 mm. Even if a copy sheet is used as the printing sheet or the above-mentioned single sheet is used, if the total sheet thickness is different, it is necessary to finely adjust the platen gap G according to the thickness.

In order to finely adjust the platen gap G, a conventional printer of this type is usually provided with a gap adjusting lever, and an operator operates the lever to move the print head 1 or the print head 1. The platen 2 is moved to adjust the gap. If this gap adjustment is inappropriate, the desired print quality cannot be obtained, and especially if the platen gap G is too narrow, a paper jam will occur at this portion, causing a trouble in use.

In order to solve this problem, some high-end printers have a mechanism for automatically adjusting the platen gap G. This is generally called an auto gap adjusting mechanism. This auto gap adjusting mechanism is (1) a mechanism for detecting the thickness of the paper, (2)
It is composed of a mechanism for automatically moving the print head 1 or the platen 2 in order to obtain a predetermined platen gap according to the detected sheet thickness.

[0007]

In recent years, the auto gap adjusting mechanism as described above has been widely adopted in order to prevent a trouble in use caused by a defective gap adjustment. However, this mechanism has the following problems. In other words, with hard paper or thick continuous paper, the perforation fold, or so-called tent tension, is large, so if the platen gap is set based on the paper thickness alone, the paper may not pass through the narrow platen gap. Occurs. In the case of a printer having a manual gap adjusting mechanism, when such a problem occurs, it is possible to use a gap slightly wider than a predetermined gap while sacrificing print quality.

However, such adjustment cannot be performed by the printer having the auto gap adjusting mechanism. A printer having a conventional auto gap adjusting mechanism is generally restricted in specifications of the paper to be used, and the ability to handle various kinds of paper, which is one of the features of the wire type dot printer, is considerably lowered. There is.

An object of the present invention is to eliminate the drawbacks of the conventional printing apparatus having the auto gap adjusting mechanism as described above, that is, to cope with various kinds of printing paper and to make the gap setting deficient. It is to prevent the trouble in use caused by.

[0010]

SUMMARY OF THE INVENTION A platen gap adjusting method for a printing apparatus according to the present invention is a printing apparatus having an auto gap adjusting mechanism for automatically adjusting a platen gap between a print head and a platen. When a signal is received, the platen gap between the print head and the platen is temporarily widened before the page-changing operation to make the page-changing operation.

[0011]

When the modified page signal is received, the platen gap between the print head and the platen is temporarily made wider than that during the printing operation to execute the modified page operation.
Even if the paper to be used is hard or thick, and the perforation of the perforation, that is, the so-called tent tension, is large, the paper is easily separated from the print head by the platen gap that is wider than during printing. The page operation can be performed by passing between the platens. When printing,
The print gap adjusting mechanism can automatically set the platen gap between the print head and the platen to an optimum value according to the thickness of the paper to be used, and thus high print quality can be achieved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the printer shown in FIG. 1, the mechanism for driving the print head, the mechanism for transferring the paper, etc. are the same as those used in the conventional printer.
Omitted. Further, since the normal printing operation is the same as the conventional one, the description thereof will be omitted.

The printer A used in the present invention has a mechanism similar to the conventional auto gap adjusting mechanism, and the CPU 6 receives a gap designating signal from the paper thickness detecting section 5 of this auto gap adjusting mechanism. . The CPU 6 drives the pulse motor 7 through a motor driver (not shown) on the basis of the gap designating signal, whereby, for example,
The platen gap is adjusted by moving the print head 1 back and forth with respect to the platen 2.

By the flow chart shown in FIG. 2, the first
The operation of the printer shown in the figure will be described.

In step ST1, C of printer A
The PU 6 determines whether the signal received from the host computer B via the interface (I / F) 8 is a modified page signal. When it is not a modified page signal, a predetermined printing operation is executed with a platen gap preset based on the gap designating signal from the host computer B (step ST2).

In step ST3, it is determined whether or not the printing is completed. If not, the process returns to step ST1. If the signal from the host computer B is judged to be a modified page signal, step ST4 is executed. In step ST4, the CPU 6 drives the pulse motor 7 to move the print head 1 backward with respect to the platen 2,
Make the platen gap wider than the platen gap during printing. After this step ST4, the modified page operation is executed and the next page is cued (step S).
T5).

Further, in step ST6, before the printing operation is started, the CPU 6 drives the pulse motor 7 to move the print head 1 forward with respect to the platen 2 and return to the platen gap during the printing operation. After that, the printing operation of the next page is executed (step ST2). After that, the above steps are repeatedly executed until the printing is completed.

Therefore, even if the so-called tent tension at the perforation of the perforations of the continuous paper to be used is large, the paper can be easily separated between the print head and the platen by the platen gap which is wider than that in the printing operation. After passing through, the page operation can be performed without causing a paper jam.

[0019]

As described above in detail, in the printer having the auto gap adjusting mechanism, the printing operation can be always performed while maintaining the optimum platen gap, and the paper jam and the like caused by the modified page operation can be performed. Trouble can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a printing apparatus used in the present invention.

FIG. 2 is a flow chart showing an embodiment of the present invention.

FIG. 3 is a diagram for explaining a conventional example.

[Explanation of symbols]

 1 Print Head 2 Platen 5 Paper Thickness Detector 6 CPU 7 Pulse Motor

Claims (1)

[Claims] 1. A printer having an auto gap adjusting mechanism for automatically adjusting a platen gap between a print head and a platen, when a modified page signal is received,
A platen gap adjusting method for a printing apparatus, wherein the platen gap is made wider than the platen gap at the time of printing operation to perform a modified page operation.