JPH0930075A - Serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serial printer which prevents lowering of processing throughput without generating paper jam. SOLUTION: A head gap between a print head 11 mounted on a carriage 12 and a platen 20 is adjusted by moving a shaft 18 in a direction of A-B. The shaft 18 is moved by rotating a stepping motor 17. Before printing is started, the head gap is properly adjusted, a distance from a retracting position of the print head 11 to a proper head gap position is stored, the print head 11 is moved from the retracting position to the proper head gap position at the time of acceleration of the print head 11 in printing operation, and the print head 11 is moved to the retracting position from the proper head gap position at the time of deceleration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer in which a print head moves in a spacing direction for printing.
In particular, the present invention relates to a serial printer having a mechanism for adjusting a gap (head gap) between a print sheet and a print head.

[0002]

2. Description of the Related Art Generally, in a conventional serial printer,
Some have a mechanism for adjusting the head gap according to the thickness of the printing paper. The head gap at the time of printing is set to about 0.25 mm, and once the head gap is set according to the thickness of the paper used, the head gap is kept until the end of printing. However, in such a conventional printer, when the side edge of the paper is rolled up or the edge of the paper is raised due to a paper staple or the like, a ribbon attached to the tip of the print head during a spacing operation or a line feed operation is performed. There was a problem that the protector would catch and tear the paper.

In order to deal with such a problem, there has been proposed a serial printer in which a line feed is performed while avoiding a stapler at the end of the sheet. In this type of printer, after the printing of one line is completed, the print head is moved to the center of the paper, and line feed is performed in this state.

[0004]

However, in the above-described conventional printer which performs line feed after moving the print head to the center of the paper, it is possible to prevent the occurrence of a paper jam at the time of line feed operation, but at the time of spacing operation. There is a problem in that the occurrence of paper jam cannot be prevented and the print head is moved to the center of the paper every time a line feed occurs, so that the throughput of the printing process is reduced.

[0005]

In order to solve the above-mentioned problems, the present invention has a gap adjusting mechanism for adjusting the gap between the paper wound around the platen and the print head, and moves the print head in the spacing direction. In a serial printer that moves and prints on a sheet, a measuring unit that measures an appropriate gap between the print head and the sheet adjusted by the gap adjusting mechanism, and a storage unit that stores the appropriate gap measured by the measuring unit. Then, during the acceleration operation from the starting point of the spacing operation until the print head reaches a predetermined spacing speed, the print head is brought closer to the paper by the gap adjusting mechanism until the proper gap stored in the storage means is reached, and printing is performed. Separate the print head from the paper during deceleration operation from the end point to the point where the print head spacing operation ends. Characterized in that a control unit for performing control.

[0006]

According to the present invention having the above-mentioned structure, the proper gap adjusted by the gap adjusting mechanism is measured at the central portion of the paper by the measuring means before the printing is started, and the measured value is stored in the storage means. Keep it. Before starting the spacing operation, the print head is placed away from the paper, and is stored in the storage means during the acceleration operation from the start point of the spacing operation for printing until the print head reaches a predetermined spacing speed. The gap adjusting mechanism brings the print head close to the sheet until the proper gap is reached. Further, the print head is separated from the paper from the proper gap stored in the storage means during deceleration operation from the print end point to the point where the print head spacing operation ends. That is,
Since the print head is located away from the paper at the edge of the paper where printing is not performed, the tip of the print head does not catch the paper. Since the operation of separating the print head from the paper is performed during the spacing operation, the throughput of the printing process does not decrease.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are assigned the same reference numerals. FIG. 1 is a perspective view showing a head gap adjusting mechanism of an embodiment according to the present invention, and FIG. 2 is a schematic side view showing a head gap adjusting mechanism of the embodiment.

Referring to FIG. 1, a serial printer 10 of this embodiment has a print head 11, a carriage 12, a ribbon protector bracket 13, and a stepping motor 1.
7 and the platen 20 and the like. The print head 11 is a dot impact type print head, and performs printing by bringing the tip of the wire into contact with the paper 19 on the platen 20. The carriage 12 carries the print head 11 and the shaft 18
Supported by The shaft 18 is provided with an adjusting cam 22a and a gear 23 at one end, and an adjusting cam 22b and a slit disk 24 at the other end.
The shaft 18 is moved toward the cam follower 26 by springs 25 attached to both ends. Further, the gear 23 provided at one end of the shaft 18 is connected to the stepping motor 1 via the gear trains 27a, 27b and 27c.
7 rotations are transmitted.

The ribbon protector bracket 13 presses the paper 19 against the platen 20.
1 so that it is located between the platen 20 and the platen 20.
It is fixed to 2. The platen 20 is rotated by a line feed (LF) motor, which will be described later, to feed the paper 19.
An ink ribbon (not shown) is arranged between the tip of the print head 11 and the ribbon protector bracket 13.

When the stepping motor 17 is rotated in the direction of the arrow in the drawing, the shaft 18 is rotated via the gear trains 27a, 27b, 27c and the gear 23, the carriage 12 is moved in the direction A in the drawing, and the stepping motor 17 is moved. When is rotated in the opposite direction, the carriage 12 moves in the B direction in the figure. The position of the carriage 12 is monitored by counting changes in the slit signal of a gap adjust sensor 28 that sandwiches a slit disk 24 attached to the other end of the shaft 18. Before starting printing, stepping motor 1
7 is rotated to move the carriage 12 in the B direction, and the ribbon protector bracket 13 is abutted against the paper 19. The abutment of the ribbon protector bracket 13 is detected by the auto gap sensor 29 shown in FIG. 2, the abutment of the ribbon protector bracket 13 is stopped at the time of detection, and then the stepping motor 17 is rotated in the reverse direction by a certain amount. As a result, the head gap between the print head 11 and the paper 19 is set.

FIG. 3 is a block diagram showing the control system of this embodiment. In the figure, the CPU 31 uses the program RO
Each part is controlled according to the control procedure stored in M32. The RAM 33 serves as a work data area for holding print data sent from the host device via the interface circuit 34 and for various calculations. The timer A35 is for creating the drive timing of the LF motor 36 that rotates the platen 20, and the CPU is provided at predetermined time intervals.
An interrupt signal 37 is generated to 31. The timer B38 is for creating the drive timing of the stepping motor 17, and an interrupt signal 39 is sent to the CPU 31 at predetermined time intervals.
Occurs. The CPU 31 performs phase switching of each motor and control of energization time by the interrupt signals 37 and 39. Timer C
Reference numeral 40 is for creating the drive timing of the ribbon motor 41 for feeding the ink ribbon, and when the count is started by the CPU 31, its output is given to the ribbon motor drive circuit 42. As a result, the ribbon motor drive circuit 42 rotates the ribbon motor 41, and the rotation is performed until the CPU 31 gives a count stop command to the timer C40.

The head drive circuit 43 is used for the print head 11.
The space motor drive circuit 44 drives a space motor 45 that moves the carriage 12 in the spacing direction. The LF motor drive circuit 46 drives the LF motor 36 that rotates the platen 20, and the ribbon motor drive circuit 42 rotates the ribbon motor 41 as described above. The gap motor drive circuit 47 drives the stepping motor 17 described above.

Next, the operation of this embodiment will be described with reference to FIGS. FIG. 4 is a flow chart showing the operation of the embodiment, and FIG. 5 is an explanatory diagram explaining the operation of the embodiment.
In addition, in FIG. 5, a graph showing the position of the print head and the size of the head gap at each position (when the platen surface is 0) for the printing example “ABC ... Z” on the paper,
6 is a graph showing a speed during a spacing operation of a carriage.

First, the CPU 31 sends print data "ABC ...
When "Z" is received (step 1), a command is issued to the space motor drive circuit 44 to drive the space motor 45 to move the print head 11 to a position corresponding to the central portion of the paper 19 (for example, an intermediate position between S2 and S3 in FIG. 5). Point, where S2 indicates the print start position and S3 indicates the print end position) (step 2).
The distance from 1 and the platen 20 is GMAX shown in FIG. 5, that is, the distance when the print head 11 is retracted.

Next, the head gap is adjusted (step 3). That is, first, the stepping motor 17 is rotated to move the carriage 12 in the direction B shown in FIG. 1, and the ribbon protector bracket 13 is abutted against the paper 19. The abutment of the ribbon protector bracket 13 is detected by the auto gap sensor 29 shown in FIG. 2, the abutment of the ribbon protector bracket 13 is stopped at the time of detection, and then the stepping motor 17 is rotated in the reverse direction by a certain amount. As a result, an appropriate head gap (GPRINT) at the time of printing operation is set. At this time, the moving distance D of the print head 11 in the B direction is GMAX (withdrawal distance).
-GPRINT (appropriate head gap) is obtained (step 4). This value D is stored in the RAM 33 (step 5).

Next, the CPU 31 drives the stepping motor 17 via the gap motor drive circuit 47,
The carriage 12 is moved to the retracted position GMAX of the print head 11.
Back up (step 6). Next, the CPU 31 drives the space motor 45 via the space motor drive circuit 44 to move the carriage 12 to the acceleration point for printing (S1 in FIG. 5) (step 7). Then, the acceleration command is given to the space motor drive circuit 44 to accelerate the carriage 12 from the time T1 to the time T2, and the timer B38 is started to drive the stepping motor 17 to move the print head 11 to the paper 19 to print. By the time the head 11 reaches the point S2, the head gap is set to GPRINT (step 8). The change in the head gap due to the drive time of the stepping motor 17 is measured by counting the output of the gap adjust sensor 29. The count value of the timer B38 is compared with the count value until the print head 11 moves from the retracted position GMAX to the proper head gap GPRINT based on the value D stored in the RAM 33,
The stepping motor 17 is stopped at the time when it coincides with the statistical value. As described above, the print head 11 is accelerated to S2.
The proper head gap GPRIN
Move to T position.

When the print head 11 reaches a predetermined spacing speed (step 9), the CPU 31 causes points S2 and S3.
The print head 11 is driven via the head drive circuit 43 to and from the point to perform the printing operation (step 10). When the printing operation is completed at time T3 (step 11), CP
U31 issues a deceleration command to the space motor drive circuit 44 to decelerate the space motor 45, drives the stepping motor 17 to retract the print head 11 from the paper 19, and before the print head 11 reaches point S4. The head gap is set to the retracted position GMAX (step 12). The change in the head gap due to the driving of the stepping motor 17 is measured by counting the output of the gap adjust sensor 29 as in the above. That is, the count of the output of the sensor 29 is started at the same time as the driving of the stepping motor 17 is started. To the retracted position GMAX.

The printing operation for one line is completed as described above (step 13), but if there is more data to be printed,
Line feed for one line is performed by the LF motor 36, and the process returns to step 7. When performing a line feed, the print head 11 faces the edge of the paper 19, but is located at the retracted position GMAX, so that the print head 11 has a convex portion at the edge of the paper 19.
Never touch.

In the above embodiment, S1 and S in FIG.
Although the head gap between 2 and between S3 and S4 is changed linearly, it goes without saying that it may be changed in a curved manner. Further, when the head gap is considered to be sufficient so that the paper jam does not occur between S3 and S4, the timer A3 is set at an appropriate time point from T3 to T4.
It is also possible to start 5 and drive the LF motor 36 to automatically execute the line feed operation.

[0020]

As described in detail above, according to the present invention, the head gap is narrowed during the printing operation, and the head gap is reduced when the print head is in the position facing the edge of the paper. Since the width is wide, the ribbon protector bracket at the tip of the print head does not catch the paper, and a highly reliable serial printer can be obtained. Further, it is possible to prevent the ink ribbon and the paper from being rubbed against each other and causing unnecessary ribbon contamination. Further, since the print head for adjusting the head gap is moved at the same time when the print head is accelerated and decelerated, the processing throughput does not decrease.

[Brief description of drawings]

FIG. 1 is a perspective view showing a head gap adjusting mechanism of an embodiment.

FIG. 2 is a schematic side view showing a head gap adjusting mechanism of the embodiment.

FIG. 3 is a block diagram showing a control system of the embodiment.

FIG. 4 is a flowchart showing the operation of the embodiment.

FIG. 5 is an explanatory diagram illustrating an operation of the embodiment.

[Explanation of symbols]

 11 Print Head 17 Stepping Motor 19 Paper 20 Platen 29 Gap Sensor 31 Controller 33 RAM

Claims (2)

[Claims] 1. A serial printer having a gap adjusting mechanism for adjusting a gap between a paper wound on a platen and a print head, wherein the print head is moved in a spacing direction to perform printing on the paper. Measuring means for measuring the proper gap between the print head and the paper adjusted by the adjusting mechanism, storage means for storing the proper gap measured by the measuring means, and the print head having a predetermined spacing from the starting point of the spacing operation. During the accelerating operation until reaching the speed, the print head is brought closer to the paper by the gap adjusting mechanism until the proper gap stored in the storage means is reached, and from the print end point to the print head spacing operation end point. And a control unit that controls the print head to separate from the paper during deceleration operation. Printer. 2. The serial printer according to claim 1, wherein the control unit performs a line feed operation during deceleration operation from a print end point to a point at which the spacing operation of the print head ends.