JPH04238076A - Printer - Google Patents

Abstract

PURPOSE:To ensure that satisfactory print quality is obtained in spite of the eccentric state of a platen roll by providing a head gap adjustment device which adjusts the clearance between a printing sheet and a printing head, and controlling the drive of the adjustment device in accordance with the eccentric amount of the periphery of a platen roll at a position opposite to the printing head. CONSTITUTION:The subject printer is composed of a platen roll 1 driven to rotate with a printing sheet 100 running on the periphery, and a head gap adjustment device 80 which adjusts the clearance between the printing head 13 and the printing sheet 100 running on the periphery of a plate 100. In addition, a head gap adjustment device 90 which controls the drive of the adjustment device 80 is provided. The head gap adjustment device 90 is equipped with an eccentric amount storage device which stores the eccentric amount of the periphery of the platen roll 1 in terms of an amount corresponding to a rotating angle. Further, the device 90 controls the operation of the adjustment device 80 by reading an eccentric amount equivalent to the rotating angle of the platen roll 1 detected by a rotary phase detection device, from the eccentric amount storage device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer that automatically adjusts the gap between a print sheet and a print head along the outer periphery of a platen roll.

[0002] In recent years, as information processing speeds up, printers are required to print at higher speeds, but in order to obtain good print quality at high speeds, the gap between the printing paper and the print head ( head gap) must be adjusted with high precision.

0003

[Prior Art] Conventionally, after printing paper is sucked between a platen roll and a print head, and before starting printing, a sensor provided near the tip of the print head is pressed against the print paper, and from there The head gap was adjusted by retracting the print head by a predetermined amount.

0004

Problems to be Solved by the Invention The platen roll is driven to rotate with the printing paper aligned therewith, thereby performing a line feed. Therefore, if there is a variation in the radius from the center of rotation to the outer circumferential surface of the platen roll (that is, eccentricity of the outer circumference of the platen roll), the amount of variation will directly become a variation in the head gap, so the head gap will change with the line feed. A phenomenon occurred in which print quality deteriorated.

SUMMARY OF THE INVENTION The object of the present invention is to provide a printer that can eliminate such conventional drawbacks and maintain a constant head gap even if the platen roll is eccentric and can obtain good print quality at high speed. With the goal.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the printer of the present invention includes a platen roll 1 which is rotated with printing paper 100 along its outer periphery, as shown in FIG. A print head 13 is arranged facing the platen roll 1 to print on the print paper 100.
and the printing paper 1 along the outer periphery of the platen roll 1.
head gap adjusting means 80 for adjusting the size of the gap between the print head 13 and the print head 1;
The head gap correction means 90 is provided for driving the head gap adjustment means 80 according to the eccentricity of the outer periphery of the platen roll 1 at a position facing the platen roll 1 to correct the size of the gap. .

Note that the head gap correction means 90 has the following features:
Detected by the eccentricity storage means 31 that stores the eccentricity of the outer circumference of the platen roll 1 in advance in correspondence with the rotation angle, the rotational phase detection means 8 that detects the rotational angle of the platen roll 1, and the rotational phase detection means 8. a head gap control means 91 for reading out the eccentricity corresponding to the rotation angle of the platen roll 1 from the eccentricity storage means 31 and controlling the operation of the head gap adjusting means 80 in accordance with the eccentricity; The head gap correction means 90 corrects the gap between the printing paper 100 and the print head 13 so that it becomes the initial gap adjusted by the head gap adjustment means 80. It is better to do so.

[0008]

[Operation] Depending on the amount of eccentricity of the outer periphery of the platen roll 1 at a position facing the print head 13, the head gap correction means 90 drives the head gap adjustment means 80, so that the print paper 100 and the print head 13 are aligned along the platen roll 1.
Correct the gap (head gap) between the

[0009]

[Embodiment] An embodiment will be described with reference to the drawings.

FIG. 2 is a plan view of the printer of the embodiment, and FIG. 3 is a side view thereof. In the figure, reference numeral 1 denotes a cylindrical platen roll that is rotationally driven around a shaft 2, and the printing paper 100 that is guided so as to be in close contact with the outer peripheral surface of the roll is fed (line feed) by the rotation of the platen roll 1. Ru. 3 is
A line feed motor (step motor) for rotationally driving the platen roll 1. 4 is a gear mechanism for transmitting the rotational force to the platen roll 1.

Further, a rotation angle detection plate 7 in which a number of slits 6 for detecting rotation angles are formed is fixed to the shaft 2 of the platen roll 1. A transmission type optical sensor (rotational phase detection means) 8 is placed across the slit 6.
detects the rotation angle of the platen roll 1 and outputs the detection signal.

A carriage 12 is slidably fitted into a guide shaft sliding portion 11b arranged parallel to the platen roll 1, and a print head 13 is attached to the carriage 12 so as to face the platen roll 1. ing.

The carriage 12 is reciprocated along the guide shaft slide portion 11b by a space motor (not shown), whereby the print head 13 moves while maintaining a constant distance from the platen roll 1.

The guide shaft 11 has both ends 11a held by bearings 14 so that the print head 13 can approach and retreat from the platen roll 1, that is, approach and escape (hereinafter also referred to as "A/E"). The sliding portion 11b is eccentric with respect to both end portions 11a.

[0015] An A/E gear 15 is fixed to one of the guide shaft ends 11a.
When the gear 15 is rotationally driven by the A/E motor (step motor) 17 via the reduction gear 16, the guide shaft slide portion 11b moves in an arc shape (Y direction), and the print head 13 performs approach and escape operations. do.

Print paper 100 is placed between the platen roll 1
In order to guide the printing paper 100, the paper guide 18, which is erected and fixed on the carriage 12 facing the platen roll 1, has a sensor that is pressed against the surface of the platen roll 1 or the printing paper 100 and can detect the pressure. A pressure sensor 20 is attached.

Reference numeral 30 denotes a control unit for controlling approach and escape operations, and includes a microprocessor and the like. Detection signals from the transmissive optical sensor 8, pressure sensor 20, etc. are input to the control section 30, and control signals are output to the drive circuits of the line feed motor 3 and A/E motor 17. 31 is a random access memory (RAM) for storing data for controlling approach and escape operations.

Next, the operation of the apparatus of this embodiment will be explained with reference to the flowcharts of FIGS. 4 to 7 showing the control processing operation of the control section 30. S indicates a step.

When controlling the approach and escape operations, first the angle (phase) of the platen roll 1 is set to a reference state. Therefore, in S1, the line feed motor 3 is operated at a minimum pitch (step), and in S2, a detection signal from the transmission type optical sensor 8 is used to determine the reference phase at which the predetermined direction of the platen roll 1 faces the print head 13. When the line feed motor 3 is reached, the line feed motor 3 is stopped in S3.

In this way, when the orientation of the platen roll 1 reaches a predetermined reference phase, the A/E motor 17 is driven at the minimum pitch (step) in S11 to cause the print head 13 to approach the platen roll 1, and in S12 When the pressure sensor 20 detects that it is pressed against the platen roll 1, the A/E motor 17 is reversed in S13.
The print head 13 is escaped by a reference amount M.

Subsequently, in S14, the line feed motor 3 rotates the platen roll 1 by 30 degrees, and in S15, the A/E motor 17 is driven at the minimum pitch to cause the print head 13 to approach.

[0022] Then, in S16, when it is detected that the pressure sensor 20 is pressed against the platen roll 1, the process in S1
7, reverse the A/E motor 17 to return to the original position (S13
Escape to the position escaped by ). Then, let X be the escape amount at that time.

Next, in S18, the escape amount M when the platen roll 1 is at the reference phase and the current escape amount X
(M-X) along with the phase of platen roll 1.
Store in AM31.

Then, in S19, if the phase of the platen roll 1 is not 360°, repeat from S14.
(M-X) is obtained for each degree and stored in the RAM 31, and the process ends when the platen roll 1 rotates once. Such data storage operations only need to be performed once before the printer is used for the first time.

[0025] When using the printer, first S21
S2 sucks in the printing paper 100 and before starting printing.
In steps 2 to S24, the head gap is adjusted, and the distance between the printing paper 100 and the print head 13 is set to the reference distance.

Then, in S25, the phase of the platen roll 1 at that time is checked based on the detection signal from the transmission type optical sensor 8, and in S26, the phase corresponding to the phase is determined (M-X).
is read from the RAM 31 and set as Y. However, since (M-X) is stored only every 30 degrees in the RAM 31, for example, (M-X) with the closest phase among the stored ones is read out.

When the printing operation is performed and a line feed is to be performed, the line feed motor 3 rotates the platen roll 1 by a predetermined amount in S31 to perform a line feed, and before printing that line, in S32, Based on the detection signal from the transmission type optical sensor 8, the phase of the platen roll 1 at that time is checked, and in S33, (M-X) corresponding to the phase is read out from the RAM 31 and set as Z.

Then, in S34, the A/E motor 17 moves (M-X) in that row and (M-X) in the previous row.
-X) and correct the head gap by the difference (Z-Y),
Substitute Z for Y, end the process, and print that line. Then, each time one line of printing is completed, S31 to S35
Perform head gap correction.

Note that (M−X) to be stored in the RAM 31 may be detected and stored not at every 30° but at even smaller intervals. The data can also be stored in read-only memory (
It may be stored in a ROM).

[0030]

[Effects of the Invention] According to the printer of the present invention, the head gap is corrected according to the amount of eccentricity of the platen roll as the platen roll rotates, so that an appropriate head gap is always maintained when printing each line. This has an excellent effect of ensuring high print quality even in high-speed printing.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a plan view of the embodiment.

FIG. 3 is a side view of the embodiment.

FIG. 4 is a processing flow diagram of the embodiment.

FIG. 5 is a processing flow diagram of the embodiment.

FIG. 6 is a processing flow diagram of the embodiment.

FIG. 7 is a processing flow diagram of the embodiment.

[Explanation of symbols]

1　Platen roll 13 Print head 80 Head gap adjustment means 90 Head gap correction means 100 Printing paper

Claims (3)

[Claims] Claim 1: A platen roll (1) that is rotationally driven with a printing paper (100) along its outer periphery;
00), which is arranged to face the platen roll (1), and the printing paper (100) and the print head (13) along the outer periphery of the platen roll (1). ) and a head gap adjusting means (80) for adjusting the size of the gap between the platen roll () at a position facing the print head (13).
1) A printer comprising head gap correction means (90) for correcting the size of the gap by driving the head gap adjustment means (80) according to the amount of eccentricity of the outer periphery. 2. The head gap correction means (90) comprises:
an eccentricity storage means (31) that stores the eccentricity of the outer periphery of the platen roll (1) in advance in correspondence with the rotation angle; and a rotational phase detection means (8) that detects the rotation angle of the platen roll (1); The eccentricity corresponding to the rotation angle of the platen roll (1) detected by the rotational phase detection means (8) is read out from the eccentricity storage means (3), and the head gap is adjusted in accordance with the eccentricity. Adjustment means (
Head gap control means (91) for controlling the operation of (80)
) The printer according to claim 1, further comprising: 3. The head gap correction means (90) comprises:
The printer according to claim 1 or 2, wherein the gap between the printing paper (100) and the print head (13) is corrected to be an initial gap adjusted by the head gap adjustment means (80).