JPH10138603A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a printing quality deterioration possibly caused due to a deflection of a platen, by correcting a gap which changes whenever a platen position changes because of a platen deflection, while at the same time performing printing operation. SOLUTION: When an electric power is turned on, a gap between a platen 1 and the front end of a printing head 4 is measured. Such a measurement is performed at least in three positions including one end A, central portion B and the other end C of the platen 1. In accordance with the measurement result, a bending phenomenon of the platen 1 caused due to a pressing force of the printing head 4 and its own empty weight, may be lineally corrected, with a deflecting amount being used as a gap correction value. In this way, a gap correction table having each gap correction value corresponding to a position of the platen 1, is stored in RAM. In printing operation, the gap correction table is consulted. As soon as the carrier 3 reaches a platen position recorded on the gap correction table, the printing head 4 is caused to approach the platen 1, moving a distance equal to a gap correction value corresponding to a platen position, thereby performing a normal printing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer for performing a print output process while moving a carrier on which a print head is mounted along a platen.

[0002]

2. Description of the Related Art This type of printer is configured by rotatably supporting left and right ends of a cylindrical platen and mounting a print head on a carrier movable in a direction (main scanning direction) along the platen. Is done. As one of such printers, for example, in a wire dot printer, in a state where an ink ribbon is interposed between a platen and a print head, when paper is guided between the ink ribbon and the platen, the printer is disposed on the print head. The leading end of the wire is projected from the plurality of holes, and the leading end of the wire is struck against a platen via an ink ribbon and a sheet to perform printing output.

In a thermal head printer, when a sheet is guided between an ink ribbon and a platen in a state where an ink ribbon is interposed between the platen and the print head, a plurality of sheets are provided on the print head. Print output is performed by causing the heating element to generate heat and pressing the print head against the platen via the ink ribbon and paper.

Further, in a printer capable of printing on paper having different thicknesses by configuring the print head so as to be capable of moving toward and away from the platen and adjusting the gap between the print head and the platen, prior to printing on the paper, The head gap is measured by pressing the print head against the print head.

[0005]

In such a printer, the platen is rotatably supported at both left and right ends, and is in the state of a simple support beam. The impact of pressing,
Platen's own weight (A print head is provided above the platen,
When printing is performed by pressing down the print head, the platen is particularly bent due to its own weight, etc.)
Bending may occur.

The deflection of the platen varies depending on the position of the carrier in the main scanning direction, and the gap between the print head and the platen becomes longer by the amount of the deflection, so that the impact force depends on the position of the carrier in the main scanning direction. In some cases, a difference occurred. For example, since the platen is simply supported at both ends, both ends of the platen have a small bending, but the bending increases as the position approaches the center. Therefore, the impact force is weaker at the center of the platen than at the end.

That is, in the conventional printer, since the gap between the platen and the print head is fixed, even if the platen is bent, the influence on the impact cannot be eliminated. In addition, even if the printer can adjust the gap between the platen and the print head, after the gap is adjusted, the printout is performed with the gap constant regardless of the position of the carrier. However, the impact on impact could not be eliminated.

In view of the above, the present invention prevents print quality from deteriorating due to platen deflection by performing printout while correcting the gap that changes for each platen position due to platen deflection according to the carrier position. It is intended to provide a printer that can do so.

[0009]

According to the first aspect of the present invention, a print head is mounted on a carrier movable in a main scanning direction along a platen, and a gap between the print head and the platen is adjusted. In a printer having a gap adjusting mechanism, the gap between the platen and the print head at a predetermined position of the platen is measured in advance, and the amount of deflection of the platen is canceled based on the measured value when printing is performed. The gap adjusting mechanism is controlled in accordance with the position of the carrier, and printout is performed while adjusting the gap.

According to a second aspect of the present invention, a print head is mounted on a carrier movable in a main scanning direction along a platen, and a gap adjusting mechanism for adjusting a gap between the print head and the platen is provided. In the printer, a gap measuring means for measuring a gap between the platen and the print head at a predetermined position of the platen, and an approximate value of the amount of deflection at each position of the platen is determined based on the gap measured by the gap measuring means. And a gap correction table generating means for storing the gap correction amount in the gap correction table, and when the position of the carrier reaches each position of the platen during printing, the gap corresponding to each position of the platen is referred to with reference to the gap correction table. The print head is moved closer to the platen by controlling the gap adjustment mechanism by the correction value. And it is provided with a a print control means for printing output processing state.

According to a third aspect of the present invention, there is provided the printer according to the second aspect, wherein the gap measuring means measures the amount of deflection at least at both left and right ends and the center of the platen.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a wire dot printer will be described below with reference to the drawings. FIG. 1 is a diagram showing a main part configuration around a platen in the present embodiment, where 1 is a platen. Both ends of the platen 1 are rotatably supported on a shaft. A carrier shaft 2 is provided along the platen 1, and a carrier 3 is attached along the carrier shaft 2 so as to be movable in the main scanning direction. On the carrier 3, a print head 4 and an ink ribbon cassette 5 provided with a hole through which the tip of a wire can be inserted and removed are mounted. The ink ribbon of the ink ribbon cassette 5 is stretched so as to be interposed between the print head 4 and the platen 1.

At one end of the carrier shaft 2, there is provided a gap adjusting mechanism 6 for moving the carrier shaft 2 together with the print head to and from the platen. The gap adjusting mechanism 6 is driven by a gap adjusting motor 7 composed of, for example, a stepping motor.

FIG. 2 is a block diagram showing the configuration of the wire dot printer according to the present embodiment. Reference numeral 11 denotes a CPU (central processing unit) constituting a control unit main body;
1 is a ROM (read only memory) in which program data and the like for controlling each unit are stored in advance, 13 is various memory areas for temporarily storing data to be processed by the CPU 11, and gaps to be described later. RAM (random access memory) in which a correction table is stored, 1
4 is an I / O port, 15 is an interface (I / F),
16 is a mechanical controller. The CPU 11 and R
The OM 12, the RAM 13, and the I / O port 14 are mutually connected via bus lines 17 such as an address bus, a data bus, and a control bus.

The mechanical controller 16 includes a head driver 19 for driving the print head 18, a motor driver 22 for driving a carrier motor 21 for moving the carrier 3 along the carrier shaft 2, and a feed motor 23 for feeding the platen 1. Driving motor driver 24,
Motor driver 2 for driving the gap adjusting motor
5, a sensor driver 27 that drives a gap sensor 26 that detects the distance between the platen 1 and the tip of the print head 4,
In addition, various sensors 28 such as a paper end sensor are connected.

A host computer 31 is connected to the I / F 15 via a communication line. An operation panel 32 on which the operator performs various operations is connected to the I / O port 14.

The CPU 11 creates and prints a gap correction table as shown in FIG. First, the CPU 11 determines whether or not the initial setting at the time of turning on the power is performed in ST (step) 1. At this time, when it is determined that the predetermined initial setting has been performed, the carrier motor 21 is controlled in ST2 to move the carrier 3 to the portion A which is one end of the platen 1 shown in FIG. The gap between the platen 1 and the leading end of the print head 3 in section A is detected, and this is used as a gap measurement value in section A (gap measuring means).

Subsequently, in step ST3, the carrier motor 21 is controlled to move the carrier 3 to a portion B which is a center portion of the platen 1 shown in FIG. A gap with the tip of No. 3 is detected, and this is set as a gap measured value in the portion B (gap measuring means). Further, in step ST4, the carrier motor 21 is controlled to move the carrier 3 to a portion C which is the other end of the platen 1 shown in FIG. Is detected as a gap measurement value in the portion C (gap measurement means).

Next, in ST5, a gap correction table as shown in FIG. 4 is created based on the gaps in the sections A, B and C (gap correction table creating means). In this case, if the platen 1 is regarded as a simple support beam at both ends, it is considered that the vicinity of the central portion (B portion) is most likely to bend. For this reason, the position from one end (part A) to the other end (part C) of the platen 1 is represented by equally divided a1 to a23 (in this case, the position of the part A is a1, the position of the part B is a12, The position of the portion C is represented by a23), and the amount of bending at each of these positions is approximated by a straight line connecting one end and the center and a straight line connecting the center and the other end, thereby obtaining a gap estimated value.

The accuracy of the estimated gap value can be increased by finely dividing the gap value. However, in this case, the deflection of the platen 1 increases from one end (A) to the center (B) by +0.0.
The gap estimation value is obtained by approximating that the distance changes linearly by 01 mm and linearly changes from the center (part B) to the other end (part C) by −0.01 mm.

The gap at each position of the platen 1 is set to 0.3 mm with 0.38 mm as a gap reference.
A gap correction value is determined so as to be 38 mm. That is, the difference (bending amount) between the estimated gap value and 0.38 mm is used as the gap correction value. In this case, the print head is moved to the platen 1 by 0.01 mm, which is the minimum unit of the gap correction value.
The number of pulses of the gap adjusting motor 7 is set in advance so that the distance can be approached. Subsequently, the gap correction table created in this way is stored in the RAM 13 in ST6, and this processing ends.

If it is determined in ST1 that the initial setting is not the power-on initial setting, it is determined in ST7 whether print data has been received from the host computer 31 via the I / F 15. At this time, when it is determined that the print data has been received, the print output is performed while performing the gap correction according to the position of the carrier 3 based on the gap correction table of the RAM 13 in ST8 (print control means).

That is, the carrier motor 21 is driven to move the carrier 3 in the main scanning direction, and the position of the carrier 3 is adjusted to the platen position (a1, a1) of the gap correction table.
2,..., A23), the gap adjusting motor 7 is driven in accordance with the gap correction value at that position to bring the print head 4 closer to the platen 1. Then, a normal print output operation is performed from that state. In this way, when printing is performed for each traveling and printing of one sheet of paper is completed, this processing is completed.

In the embodiment of the present invention having such a configuration, at least one end of the platen 1 when the power is turned on,
The actual gap was measured at three points, the center and the other end, and based on the measured values, the platen 1
Of the bending caused by the pressing or the self-weight, etc., is linearly approximated, and a gap correction table in which a gap correction value corresponding to the position of the platen 1 is set using the amount of the bending as a gap correction value is stored in the RAM 13. Remember.

When actually printing on paper, the gap correction table is referred to, and when the position of the carrier 3 reaches each platen position in the gap correction table, a gap correction value (deflection) corresponding to the platen position is obtained. The print head 4 is moved closer to the platen 1 by the amount of the print head 4 to perform a normal print output operation.

As a result, the change in the gap due to the bending of each position of the platen 1 can be eliminated, and the apparent gap can be made constant. Therefore, platen 1
The impact force from the print head 4 is constant over all the positions, and the print quality can be prevented from deteriorating.

Further, since the amount of deflection at each position of the platen 1 is linearly approximated, handling and processing can be simplified. Note that the theoretical amount of deflection is a quadratic curve for a two-sided simple support beam such as the platen 1 in the present embodiment. However, since the amount of deflection itself is small, even if it is linearly approximated in practice, A sufficient effect can be achieved.

However, the amount of deflection of the platen 1 is not necessarily limited to a linear approximation, but may be a quadratic curve. Theoretically, the approximation can increase the correction accuracy.

Further, the gap is actually measured only at three positions of one end (A), the center (B), and the other end (C) of the platen 1, and the other portions (positions) are measured. Since the gap is not actually measured only by linear approximation, the time required to create the gap correction table can be minimized.

However, the measurement is not necessarily limited to the case where only the above three gaps are measured, and the gap may be measured for other portions in addition to the three gaps. Thereby, the correction accuracy can be further improved.

In the embodiment of the present invention, a case where the present invention is applied to a wire dot printer has been described.
The present invention is not necessarily limited to this, and may be applied to a thermal head printer or various printers having a gap adjustment function. This is particularly effective when applied to a printer in which the print head is pressed against the platen a relatively large number of times.

As a gap adjusting mechanism, as shown in FIG. 1, in addition to a mechanism for moving the carrier 3 together with the carrier shaft 2 to and from the platen 1, a mechanism for moving the print head 4 to and from the platen 1 is provided on the carrier 3. May be used.

[0033]

As described in detail above, according to the present invention, printing is performed while correcting a gap that changes for each position of the platen due to the deflection of the platen in accordance with the position of the carrier, thereby performing printing by the deflection of the platen. It is possible to provide a printer capable of preventing quality deterioration. By measuring the amount of deflection at least at both left and right ends and the center of the platen, a gap correction table can be created in a minimum necessary time.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration near a platen in a wire dot printer according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a wire dot printer according to the embodiment.

3 is a flowchart showing a gap correction table creation and printing process performed by a CPU shown in FIG. 2;

FIG. 4 is an exemplary view for explaining a gap correction table according to the embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Platen 3 ... Carrier 4 ... Print head 6 ... Gap adjustment mechanism 11 ... CPU

Claims (3)

[Claims] 1. A printer having a print head mounted on a carrier movable in a main scanning direction along a platen and having a gap adjusting mechanism for adjusting a gap between the print head and the platen. Measuring the gap between the platen and the print head at a predetermined position, and adjusting the gap according to the position of the carrier so as to cancel the amount of deflection of the platen based on the measured value when printing is performed. A printer which controls a mechanism and outputs a print while adjusting a gap. 2. A printer, comprising: a print head mounted on a carrier movable in a main scanning direction along a platen; and a gap adjusting mechanism for adjusting a gap between the print head and the platen. A gap measuring means for measuring a gap between the platen and the print head at a predetermined position, and an approximate value of the amount of deflection at each position of the platen is determined based on the gap measured by the gap measuring means. A gap correction table creating means for storing the gap in the gap correction table, and when the position of the carrier reaches each position of the platen during printing, the gap corresponding to each position of the platen is referred to by referring to the gap correction table. By controlling the gap adjustment mechanism by the correction value, the print head is A print control unit for performing a print output process in a state where the printer is brought close to the ten. 3. The printer according to claim 2, wherein the gap measuring unit measures the amount of deflection at least at both left and right ends and the center of the platen.