JPH028075A - Serial printer - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a serial printer that performs bidirectional printing by moving a print head in which a plurality of recording elements are arranged in a row in the sub-scanning direction in the main scanning direction. Regarding.

(b) Conventional technology - g. Serial printers use a print head in which a plurality of recording elements are arranged in a row in the sub-scanning direction (the direction in which the recording paper is transported), in the main scanning direction (the direction perpendicular to the direction in which the recording paper is transported). ) while recording. Since the recording speed of this type of printer is slow, conventionally, as shown in FIG. 5, for example, bidirectional printing of forward direction printing (white arrow) and reverse direction printing (black arrow) has been performed.

In addition, in the case of inkjet printers, the recording elements are ink nozzles, so there is a limit to the density in the sub-scanning direction, so when performing high-resolution printing, it is necessary to arrange the nozzles in a staggered manner,
A method such as providing two heads shifted by half a dot in the sub-scanning direction has been used.

(c) Problems to be Solved by the Invention When performing bidirectional printing in the above-mentioned conventional serial printer, mechanical play in the print head causes
As shown in the figure, since positional deviation occurs between forward printing and reverse printing, there is a problem in that highly accurate printing cannot be achieved when continuity of printing is required in the sub-scanning direction.

On the other hand, in an inkjet printer, arranging nozzles in a staggered manner or installing two heads in parallel makes the head complex, so it is easier to interpolate dots by bidirectional printing as shown in Figure 7. It is believed that high-resolution printing can be achieved. However, even in this case, misalignment of the head in the forward and reverse directions poses a problem.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a serial printer that can perform bidirectional printing without positional deviation.

(d) Means and Effects for Solving the Problems The serial printer of the present invention performs bidirectional printing by reciprocating a print head in which a plurality of recording elements are arranged in a sub-scanning direction in a main scanning direction. , a position detector that detects a reference position of the print head; and a position detector that detects a reference position of the print head; and a position detector that detects a reference position of the print head; first counting means for counting n pulses; and responsive to counting n pulses by the first counting means, changing the scanning direction of the printhead in a second direction opposite to the first. a scanning direction switching means for switching, a second counting means for starting pulse counting after switching to the second direction and counting the number of pulses n' until the position detector detects the reference position;
means for calculating a difference value n'-n between the count value n'' of the counting means and the count value n of the first counting means, and the difference value n'-n is used to correct positional deviation when switching the moving direction value.

With this serial printer, for example, before starting printing,
A position detector detects a reference position of the print head (for example, the starting edge of recording paper), moves the print head in a first direction (forward direction) from the reference position, and counts the number of pulses during the movement. Count by means. When the count reaches a predetermined number of n, the scanning direction switching means switches the moving direction of the print head to the second direction (reverse direction) and moves the print head.

Then, until the position detector detects the reference position, the second . The number of pulses is counted by the counting means.

If the number of pulses when the position detector detects the reference position is n゛, then if there is no mechanical play in the print head, n=
n', but in reality there is mechanical play, so n'>n. Here, calculate n'-n,
This difference value is used as a positional deviation correction value.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a schematic diagram of a serial printer showing an embodiment of the present invention. In the figure, recording paper 2 is placed on platen 1.
is installed, and this recording paper 2 is moved in the direction of arrow B (sub-scanning direction).
At the same time, a print head 3 is placed opposite to the platen 1 with the recording paper 2 in between, and the print head 3 is moved in the axial direction of the platen 1, that is, in the direction of arrow A (main scanning direction). It is configured to

As shown in FIG. 3, this print head 3 includes a plurality of recording elements (for example, heating elements 9a, 9a, . . . 9
A) is provided with a printing section 9 arranged in the sub-scanning direction, and a position detector 8 which is integrated with this printing section 9 and consists of a light emitting element 8a and a light receiving element 8b. Control part (CP
Based on the print data from 7 (composed of U, etc.), the print element drive section 5 drives each recording element 9a, 9a, . . . of the print section 9.
9a is selectively driven to print a predetermined number of dots in the sub-scanning direction, and the head conveying section 4 is configured to perform the printing operation while moving in the main-scanning direction A.

On the other hand, the light emitted from the light emitting element 8a of the position detection 2'i8 is reflected by the platen 1 or the recording paper 2, and is received by the light receiving element 8b. Starting edge of paper 2 or recording paper 2
A predetermined line printed on the line is detected and inputted to the control section 7.

This embodiment serial printer initially has printhead 3.
While moving in the forward direction, that is, from the left to the right of the drawing,
When the printing operation is performed and printing is completed to the right edge,
This time, it has a bidirectional printing function that switches directions and continues printing in the opposite direction, that is, from right to left.

In the serial printer of this embodiment, when starting a printing operation, the print head 3 is positioned at the leftmost position, and prior to the start of printing, the step of calculating the positional deviation in the forward direction and the reverse direction is provided.

Next, referring to the flowchart shown in FIG. 1, the print head 3 of the serial printer for forward printing and reverse printing
The positional deviation detection operation will be explained.

Prior to operation, it is assumed that the print head 3 is located at the leftmost position. When the operation starts in this state, first, the print head 3 moves from the left end to the right under the control of the head conveying section 4 [step ST (hereinafter referred to as ST) 1].

Then, the home position of platen 1 shown in Fig. 4: 1
0 is detected by the position detector 8 and the detection unit 6, and it is determined whether Baum position is detected (Sr2). When the head moves to the right and the home position 10 is detected, the counter is started and the reference pulse of the control unit 7 is counted to 5T.
3) It is determined whether or not the end surface 2a of the recording paper 2 shown in FIG. 4 is detected, and the number of pulses is counted until the end surface 2a is detected. After counting the number of pulses by m, when the end surface 2a of the recording paper 2 is detected, the determination of Sr4 becomes YES, and the counter is restarted to start pulse counting.

When this pulse count value N reaches n, that is, when the position detector 8 of the print head 3 reaches the position shown in FIG. At the same time, the print head 3 is reversed from the forward direction to the reverse direction (Sr1), and at the same time, the counter starts counting pulses anew (Sr1).

While continuing pulse counting, it is determined whether or not the end surface 2a of the recording paper 2 is detected by the position detector 8 (Sr9
). Pulse counting of Sr1 will continue until the position is detected. When the end surface 2a of the recording paper 2 is detected, the determination of Sr9 becomes YES, and the pulse count value n' is stored here (STIO). As mentioned above, if there is no mechanical play in the print head 3,
Ideally, n=n'' and there is no correction, but if there is normal mechanical play, naturally n'>n, so remember n-n=n'' (STII ), here, the moving direction of the head 3 is changed to the normal rotation direction again and 5T12
), and then normal data printing is performed (ST13). 3T
Unless printing is terminated at 1/I, data printing will continue until the forward direction printing becomes a line feed. 5T1
When changing the line feed or stopping the normal rotation direction to the reverse direction at step 5, the moving direction of the head 3 is reversed (ST16), and the start point of printing the next data is delayed by the correction value, that is, the number of pulses n''. When the data is printed, the deviation in the direction of movement due to mechanical backlash is corrected, and normal printing is performed.

By performing the above-described correction and repeating printing in the reverse and forward directions, it is possible to sequentially perform bidirectional printing without positional deviation.

In the above embodiment, the process for detecting positional deviation is performed before starting printing, but this process may be performed every time an operation button or the like is pressed.

Further, in the above embodiments, the printing means of the print head is an example of a thermal head, but the print head of the present invention is not limited to a thermal head.
It can be applied to various dot-type recording elements such as ink nozzle printers, wire dot printers, and optical printers.

In addition, if the recording paper 2 is wider than the print head movable width, such as fanfold paper, the edge of the recording paper cannot be detected, so in this case, the print head prints vertical lines on the recording paper before detection. However, mechanical play may be determined using this vertical line as a reference position.

(f) Effects of the Invention According to this invention, the print head is provided with a position detector separate from the print recording element, and after the position detector detects the reference position of the print head, the print head is moved in the first direction. Move by a distance corresponding to a predetermined number of pulses, then switch the moving direction to the second direction, count the number of pulses until the reference position is detected, and calculate the number n of pulses and the count in the first direction. Since the difference value from the time n is used as the positional deviation correction value, bidirectional printing without positional deviation is possible, and the recording speed in the serial printer is increased accordingly.

Furthermore, since bidirectional printing is possible by shifting the image by half a dot compared to the resolution of the recording element of the print head itself, the printing resolution can be increased.

Furthermore, during bidirectional printing, positional deviations due to mechanical backlash inherent in the device can be automatically adjusted without having to be individually adjusted before military use, which is very convenient in terms of operation.

Furthermore, since the positional deviation can be corrected in response to changes in mechanical play over time, there are various advantages such as being able to continue printing operations with high precision for many years.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the operation for calculating the positional deviation correction value of a serial printer according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a serial printer showing an embodiment of the present invention. 3 is a schematic perspective view of a print head used in the same serial printer, FIG. 4 is an explanatory diagram illustrating the operation for detecting a positional deviation correction value in the same serial printer, and FIG. 5 is an example Figure 6 is an example of printing to explain bidirectional printing by a serial printer. Figure 6 is an example of printing to explain positional deviation due to bidirectional printing. Figure 7 is an example of printing when obtaining high resolution by bidirectional printing. It is a printing example figure. 1: Nib platen, 2: Recording paper, 3: Nib print head, 4: Head transport section, 5: Print element drive section, 6: Detection section, 7: Control section, 8: Position detector. Figure 1

Claims (1)

[Claims] (1) In a serial printer that performs bidirectional printing by reciprocating a print head in which a plurality of recording elements are arranged in the sub-scanning direction in the main-scanning direction, a position detector that detects a reference position of the printhead; a first counting means for counting a predetermined number of pulses n after the position detector detects a reference position during the process of moving the print head in a first direction in the main scanning direction;
scanning direction switching means for switching the scanning direction of the print head to a second direction opposite to the first direction in response to counting n pulses by the first counting means; a second counting means that starts pulse counting after switching and counts the number of pulses n' until the position detector detects the reference position; and a count value n' of the second counting means and the first means for calculating a difference value n'-n of the count value n of the counting means, and this difference value n'-n is used as a positional deviation correction value when switching the moving direction. printer.