JP2000301793A - Method for correcting carriage driving and image output apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive a carriage highly accurately by using a value of a corrected coefficient in place of a coefficient for converting a designated move amount of the carriage to the number of drive steps of a stepping motor to calculate the number of drive steps. SOLUTION: When a main power source of the apparatus is turned on, the number (x) of steps for driving a stepping motor to move a carriage by the number (m) of dots corresponding to a predetermined distance is calculated by a dot-step conversion coefficient (a) (S21). The motor is driven by the number of steps (x) to move the carriage (S22). Positions of the carriage before and after the move are read from a linear scale, and a drive distance (n) of the carriage after the move is obtained (S23). The dot→step conversion coefficient (a) is corrected to be a dot→conversion coefficient (b) (S24), and a value of the coefficient (b) is temporarily stored in a RAM (S25).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image output apparatus having a structure in which a carriage is moved by using a stepping motor, and more particularly, to a carriage drive correction method capable of correcting an error in a movement amount when the carriage is moved. About.

[0002]

2. Description of the Related Art In an image output apparatus for driving a carriage on which a recording head is mounted using a stepping motor, conventionally, in order to accurately move the carriage by a desired movement amount, the movement amount is converted into the number of motor steps. The stepping motor is driven by converting the desired movement amount into the number of steps using a coefficient.

[0003]

The coefficients are calculated on the basis of mechanical drawings in the design stage or are adjusted based on many samples. Was not tailored to. That is, errors in the accuracy of components that transmit the drive of the motor to the object in the manufacturing stage have not been considered.

[0004] For this reason, when there is a large error between the components and the dimensions of the design drawing, the actual moving distance of the carriage to be driven may be several dots longer than the target moving distance. .

Therefore, it is necessary to improve the movement accuracy of the carriage, and the accuracy of the components must be improved. However, in order to make accurate components,
There has been a problem that extra cost is required compared to normal parts.

Therefore, according to the present invention, it is possible to accurately drive an operation target irrespective of the variation of the components by taking into account the variation in accuracy in the manufacturing stage of the component (pulley or the like) for transmitting the drive of the motor to the carriage. An object of the present invention is to provide a carriage driving correction method and an image output device that can perform the correction.

[0007]

A carriage drive correction method according to the present invention is a carriage drive correction method for correcting the number of drive steps of a stepping motor for driving a carriage on which a recording head of an image output device is mounted. The stepping motor is step-driven by the carriage movement amount, the carriage movement amount actually obtained by this step drive is measured, and the predetermined carriage movement amount is compared with the actually obtained carriage movement amount. The coefficient a for converting the moving amount of the carriage into the number of driving steps of the stepping motor is corrected based on the comparison result, and thereafter, when calculating the number of driving steps from the instructed moving amount of the carriage, the coefficient a It is characterized in that the corrected coefficient (coefficient b) is used instead of a.

By performing such correction for each image output device, it becomes possible to drive the carriage with high accuracy irrespective of the variation in dimensional accuracy in the manufacturing stage of the component.

The coefficient b can be calculated, for example, by the following equation.

B = a * (m / n)

Here, m is the designated movement amount, and n is the actually measured movement amount.

An image output apparatus according to the present invention, in an image output apparatus having a carriage on which a recording head is mounted, a stepping motor for linearly reciprocating the carriage, actual measurement means for actually measuring the amount of movement of the carriage, Motor driving means for converting the moved amount into the number of driving steps of the stepping motor in accordance with the predetermined coefficient a, and driving the stepping motor; the designated amount of carriage movement and the carriage movement actually measured by the actual measuring means. A coefficient correcting means for obtaining a coefficient b obtained by correcting the coefficient a by comparing with a quantity.

[0013] The actual measuring means includes, for example, a linear scale arranged in parallel with the carriage, and a linear scale sensor mounted on the carriage. As the linear scale and the linear scale sensor, existing ones can be used for the image output device, so that new components are not required as actual measurement means.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a configuration example around a carriage of a printer as an example of an image output apparatus. FIG. 2 is a top view of the configuration around the carriage of the printer as viewed from the direction A in FIG.

The rotation of the stepping motor 11 is directly reflected on the rotation of the pulley 12, and this rotation is transmitted to the carriage drive belt 13. A carriage 14 is attached to a predetermined portion of the belt 13 and the pulley 12
Is converted into a linear reciprocating motion of the carriage 14.
A well-known linear scale 15 serving as a reference for the position of the carriage is arranged along the movement path of the carriage 14. The movement of the carriage 14 can be recognized by the linear scale sensor 16 mounted on the carriage 14 reading the linear scale 15.

FIG. 3 shows a block diagram of a control device including the stepping motor 11 and components for controlling the same. The control device includes a CPU 111 and this CPU
ROM 112 storing an operation program 111 and necessary fixed data, and an RA holding various data.
M113, and a motor driver 116 that supplies a predetermined drive current to the motor coils of each phase of the stepping motor 11 under the control of the CPU 111.

From the CPU 111, a clock pulse for driving the stepping motor 11 in a so-called micro-step drive and a signal (not shown) for specifying a rotation direction are supplied to the motor driver 116. In response to these signals, motor driver 116 supplies a control signal for performing micro-step driving to an internal transistor (not shown). As a result, a predetermined current flows through the motor coils of each phase of the stepping motor 11, and the stepping motor 11 rotates in the specified direction by the specified number of microsteps.

Next, a description will be given of a method of correcting an error in a moving distance due to a mechanical difference when calculating the number of driving steps of a stepping motor with respect to a desired moving distance of a carriage in the printer.

Let r be the diameter of the pulley 12 according to the mechanical design drawing.
(Mm), the step angle per pulse of the stepping motor 11 is i (°), and the resolution of the linear scale is 36.
0 (dpi). At this time, the number of steps of the stepping motor for one dot of the linear scale is calculated. Since the resolution of the linear scale is 360 dpi,
The distance d per linear scale dot is

D = 25.4 / 360 mm. Therefore, the moving distance D per step of the stepping motor is as follows: the step angle is i ° and the diameter of the pulley is rmm.

D = (r * π) / (360 / i) mm

Therefore, the number of steps a of the stepping motor per dot is:

A = (25.4 / 360) / ｛(r * π)
/ (360 / i)｝ step a is a value calculated from a design drawing and is a constant. In general, the number N of motor drive steps for moving the carriage by k dots is

N = k * a steps That is, the constant a is considered to be a coefficient for converting the moving distance of the carriage into the number of motor drive steps.

Based on the above, the coefficient a for converting the moving distance of the carriage into the number of steps is corrected.

FIG. 4 is a flowchart showing an example of a process for correcting the coefficient a for converting the moving distance of the carriage into the number of steps. In the present embodiment, this processing is performed in the initialization processing when the power of the printer is turned on. Therefore, it is possible to cope with mechanical errors due to aging.

First, consider the carriage movement of the number m (dots) of dots corresponding to a predetermined distance when the main power of the apparatus is turned on. At this time, the number of steps x for driving the stepping motor is calculated based on the dot → step conversion coefficient a derived from the design theoretical value (S21). That is, the number of steps x is

X = m * a steps Next, the motor is actually driven by the number of steps to move the carriage (S22).

The position before and after the movement of the carriage 14 is read from the linear scale 15, and the driving distance n (dot) of the carriage 14 after the movement is obtained (S23).

Here, if all parts constituting the apparatus have exactly the same dimensions as the design drawings, the designated number m of dots and the actually measured number n of dots should be equal. However, in practice, m ≠ n in many cases because the dimensional accuracy of the components such as the pulley diameter includes a slight error. Therefore, the dot → step conversion coefficient a is corrected as follows.

Assuming that the corrected dot → step conversion coefficient is b, the number of driving steps of the stepping motor is x, so that the movement amount Nt obtained from the theoretical value based on the design drawing and the actual movement amount Na And do
When calculated from the t → step conversion coefficients a and b,

Nt = x / a (dot),

Na = x / b (dot)

Since the values of these movement amounts Nt and Na are m and n (dots), respectively, the following two equations hold.

X / a = m,

X / b = n From these two equations,

A proportional relationship of m: n = x / a: x / b is established. The following equation is derived from this proportional equation (S24).

B = a * (m / n) Here, since a, m and n are known, the corrected dot → step conversion coefficient b based on the coefficient a can be obtained. The value of the coefficient b is temporarily stored in the RAM 113 (S25), and is used to calculate the number of steps corresponding to the target movement amount when driving the carriage. That is, from the next drive of the stepping motor, the number of steps taking into account the error in the dimensional accuracy of the component parts can be calculated by using the corrected dot → step conversion coefficient b when calculating the number of drive steps. Thus, the carriage can be accurately moved.

Although the preferred embodiment of the present invention has been described, various modifications and changes are possible. For example,
In the above description, the correction coefficient b is obtained in the initialization processing at the time of turning on the power, but may be obtained at another arbitrary time. Further, it is also possible to obtain a correction coefficient b corresponding to each device before shipment of the device and store it in the ROM.

[0041]

According to the present invention, the carriage of the image output apparatus can be driven with high accuracy irrespective of the dimensional accuracy of the mechanical components. Also, there is no need for extremely high precision mechanical components. Moreover, since the present invention can be realized mainly by software, no new mechanical components are required. Therefore, it is possible to drive the carriage of each image output device with high accuracy without increasing the cost of the device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example around a carriage of a printer as an image output device according to an embodiment of the present invention.

FIG. 2 shows a configuration around a carriage of the printer of FIG. 1;
FIG. 3 is a diagram viewed from a direction A of FIG.

FIG. 3 is a block diagram of a control device including a stepping motor 11 and components for controlling the stepping motor 11 according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating an example of a process for correcting a coefficient a for converting a moving distance of a carriage into a number of steps according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 stepping motor 12 pulley 13 carriage drive belt 14 carriage 15 linear scale 16 linear scale sensor

Claims (5)

[Claims] 1. A carriage drive correction method for correcting the number of drive steps of a stepping motor for driving a carriage on which a recording head of an image output device is mounted, the method comprising the steps of: The carriage movement amount actually obtained by the driving is measured, the predetermined carriage movement amount is compared with the actually obtained carriage movement amount, and the instructed carriage movement amount is set as the number of driving steps of the stepping motor. The coefficient a for conversion is corrected based on the comparison result. Thereafter, when calculating the number of driving steps from the instructed moving amount of the carriage, the corrected coefficient (coefficient b) is used instead of the coefficient a. A carriage driving correction method, characterized by using the following values: 2. The method according to claim 1, wherein said coefficient b is calculated by the following equation. b = a * (m / n) where m is the designated movement amount and n is the actually measured movement amount. 3. An image output apparatus having a carriage on which a recording head is mounted, a stepping motor for linearly reciprocating the carriage, actual measurement means for actually measuring an amount of movement of the carriage, and a predetermined amount of movement. Motor driving means for converting the number of steps of the stepping motor into drive steps in accordance with the coefficient a, and driving the stepping motor; and comparing the coefficient a with the carriage movement instructed and the carriage movement actually measured by the actual measuring means. An image output device comprising: a coefficient correction unit that obtains a coefficient b obtained by correcting. 4. An image output apparatus according to claim 3, wherein said actual measuring means comprises a linear scale arranged in parallel with said carriage, and a linear scale sensor mounted on said carriage. 5. The coefficient correction means calculates the coefficient b from the coefficient a by the following equation.
The image output device as described in the above. b = a * (m / n) where m is the designated carriage movement amount and n is the actually measured carriage movement amount.