JPH07137342A - Serial printer - Google Patents

Abstract

PURPOSE:To correct a printing shift correspondinly to a carrier shift value by a method wherein a stepping motor is controlled by a control means on the basis of a carrier, shift calculated by a carrier shift calculation means. CONSTITUTION:The number of pulses pAB required of a carrmer 10 to move in a forward direction A B is equal to the number of pulses pBA required to move in a return directmon B A. The number of pulses pOA remaining to a point A is calculated. In this operation, a difference 10 pulse number is found as a shift in recognition of a point 0 in a forward path and a return path and defined as a carrier shift Z. Namely, a travel amount of the carrier 10 generated by imparting the difference in pulse number to a stepping motor 12 is a carrier shift Z between the forward path and return path of the carrier 10. Therefore, by setting a printing start timing of a return-path action with a time lag from that of a forward-path action by the travell amount, a printing shift in two-way printing can be effectively corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer, and more particularly, to a serial printer having a function of correcting print misalignment in forward and reverse paths that occur during bidirectional printing operation.

[0002]

2. Description of the Related Art In a serial printer, a backlash of a motor, a gear and the like occurs during a bidirectional printing operation, so that a "shift" of a carrier having a print head occurs between a forward path and a backward path. Conventional serial printers do not have effective means for detecting this carrier shift. Therefore, the carrier shift is obtained in advance, and based on this, the print start timing of the backward path with respect to the forward path is corrected.

[0003]

However, this conventional serial printer has a problem that carrier shift occurs in the following cases.

For some reason, the carrier shift obtained in advance may not match the actual carrier shift from the beginning.

Due to changes in the history, the actual carrier deviation may not match the previously obtained carrier deviation.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a serial printer which can correct a carrier shift even if the value of the carrier shift changes due to changes in history or the like.

[0007]

SUMMARY OF THE INVENTION A serial printer according to the present invention has been made in order to achieve the above-mentioned object, and has a carrier having a print head, a stepping motor for generating a driving force, and this stepping motor. Motor control means controlled by a pulse signal, a carrier moving mechanism for moving the carrier in the forward direction or the backward direction by the driving force of the stepping motor, and a fixed position in the moving area of the carrier and the fixed position. And a carrier detection means for obtaining a detection signal when the carrier passes through the carrier, and a deviation between the forward direction and the backward direction of the carrier is calculated based on the detection signal of the carrier detection means and the pulse signal of the motor control means. And carrier shift calculation means. The motor control means controls the stepping motor based on the carrier shift calculated by the carrier shift calculation means.

[0008]

The motor control means controls the stepping motor by the pulse signal. The stepping motor moves the carrier in the forward direction or the backward direction via the carrier moving mechanism. Further, the carrier detecting means is installed at a fixed position in the carrier moving area, and a detection signal is obtained when the carrier passes through the fixed position. By inputting the pulse signal and the detection signal, the carrier shift calculation means can detect the number of pulse signals required for the carrier to move the distance between this fixed position and another fixed position. Subsequently, the carrier shift calculating means can calculate the carrier shift by comparing the number of pulse signals detected in this way in the forward direction and the backward direction.
Finally, the motor control means controls the stepping motor so as to eliminate the carrier shift based on the carrier shift calculated by the carrier shift calculation means.

[0009]

FIG. 1 shows an embodiment of a serial printer according to the present invention, and FIG. 1 (a) is a block diagram showing the overall construction.
FIG. 1B is a graph showing the relationship between carrier position and velocity. Hereinafter, description will be given based on this drawing.

The serial printer according to the present invention comprises a carrier 10 having a print head, a stepping motor 12 for generating a driving force, a motor control means 14 for controlling the stepping motor 12 by a pulse signal p, and a driving of the stepping motor 12. A carrier moving mechanism 16 that moves the carrier 10 in the forward direction A → B or the backward direction B → A by force, and when the carrier 10 is installed at a fixed position O in the moving region of the carrier 10 and the carrier 10 passes through the fixed position O. Based on the detection signal i of the carrier detection unit 18 and the pulse signal p of the motor control unit 14 between the forward direction A → B and the backward direction B → A of the carrier 10. And a carrier shift calculating means 20 for calculating the shift z. Then, the motor control means 14 controls the stepping motor 12 based on the carrier shift z calculated by the carrier shift calculation means 20.

Each part will be described in more detail.

The carrier moving mechanism 16 is composed of gears 30, 30 one of which is connected to the driving force transmission shaft 12a of the stepping motor 12 and a belt 32 stretched around these gears 30, 30. ing.

The carrier detecting means 18 comprises a sensor for detecting an object by non-contact or mechanical contact by light, magnetism or the like.

Point A represents the forward movement start point and the backward movement stop point. Point B represents the forward movement stop point and the backward movement start point. Carrier 10 between points C and D
Is a region in which the carrier moves at a constant speed, and the carrier 10 is not affected by the backlash of the stepping motor 12, the gears 30, 30, and the like. The carrier detection means 18 is installed at an arbitrary point O in this area.

Next, the operation of the serial printer according to this embodiment will be described focusing on the operation of the carrier shift calculation means 20.

First, on the outward path of the carrier 10, the number of pulses pAO given to the stepping motor 12 from the movement start point A to the passage of point O is counted. At the same time, by the number of pulses pAB given to the movement from point A to point B, B
The number of remaining pulses pOB up to the point pOB (= pAB-pAO) is calculated. Next, on the return path of the carrier 10, the movement start point B
The number of pulses pBO given to the stepping motor 12 from the point to the point O is counted. Here, since the pulse numbers pAB and pBA required for the movement in the forward direction A → B and the backward direction B → A are the same amount, similarly, the number of remaining pulses pOA up to the point A is pOA.
Calculate (= pAB-pBO).

From the above operation, the difference in pulse number S = pAO-
pOA (or S = pBO-pOB) becomes the deviation of the O point position recognition on the forward path and the backward path, that is, the carrier deviation z.

That is, the amount of movement of the carrier 10 caused by applying the difference S in the number of pulses to the stepping motor 12 becomes the carrier deviation z between the forward path and the backward path of the carrier 10. Therefore, by delaying the print start timing with respect to the forward path at the time of the backward path operation by this moving amount, the print deviation in the bidirectional printing is effectively corrected.

In this embodiment, the carrier detecting means 1
Since No. 8 is installed in the constant speed operation region of the carrier 10, not only backlash of the stepping motor 12, gear 30, etc. but also tension and slippage of the belt 32 can be detected. Further, since the carrier shift z is detected based on the difference between the forward path and the backward path of the carrier 10, the carrier detecting means 18 is not required to be attached with high accuracy.

[0020]

According to the present invention, based on the pulse signal for controlling the stepping motor and the detection signal due to the passage of the carrier, the number of pulse signals required for the carrier to move a certain distance is determined as the forward and backward directions. The carrier shift can be detected in real time by comparing with the direction. Therefore, even if the value of the carrier shift changes due to changes in history or the like, the carrier shift can be corrected correspondingly.

[Brief description of drawings]

FIG. 1 shows an embodiment of a serial printer according to the present invention, and FIG. 1 (a) is a block diagram showing the overall configuration.
(B) is a graph showing the relationship between the position and velocity of the carrier.

[Explanation of symbols]

 10 carrier 12 stepping motor 14 motor control means 16 carrier moving mechanism 18 carrier detecting means 20 carrier deviation calculating means i detection signal p pulse signal z carrier deviation

Claims (3)

[Claims] 1. A carrier having a print head, a stepping motor for generating a driving force, a motor control means for controlling the stepping motor with a pulse signal, and a forward direction or a backward direction of the carrier by the driving force of the stepping motor. A carrier moving mechanism that moves to a carrier, a carrier detecting unit that is installed at a fixed position in a moving region of the carrier and that obtains a detection signal when the carrier passes through this fixed position, a detection signal of the carrier detecting unit, and A carrier deviation calculating means for calculating a deviation between the forward direction and the backward direction of the carrier based on a pulse signal of the motor controlling means, wherein the motor controlling means calculates the carrier deviation calculated by the carrier deviation calculating means. Based on the control of the stepping motor. Printer. 2. The carrier shift calculating means calculates the number of the pulse signals from the movement start point in the forward direction to the fixed position where the carrier detecting means is installed, and the fixed position where the carrier detecting means is installed. 2. The serial printer according to claim 1, wherein the shift between the forward direction and the backward direction of the carrier is obtained by taking a difference from the number of the pulse signals up to the movement stop point in the backward direction. 3. The carrier shift calculation means detects the number of the pulse signals from a fixed position where the carrier detection means is installed to a movement stop point in the forward direction and the carrier detection from a movement start point in the backward direction. 2. The serial printer according to claim 1, wherein the deviation between the forward direction and the backward direction of the carrier is obtained by taking the difference from the number of the pulse signals up to the fixed position where the means is installed.