JPH05122966A - Printer controller - Google Patents

Abstract

PURPOSE:To shorten the processing time for operating the output value of a P-I compensator, in a printer which controls a DC motor using the P-I compensator. CONSTITUTION:The value of having multiplied the deviation from the target speed by the gain of an integration factor and the value of having multiplied the deviation by the gain of a proportion factor are stored as a data table in advance in a ROM11, corresponding to the speed of a DC motor 1. An encoder 6 detects the speed and data are taken out of the table, according to the detected value of the speed and the output value of a P-I compensator is operated. Hereby, the processing time for operating the output value of the P-I compensator is shortened, and a printer controller, which is high in control accuracy even in the case that the target speed of revolution is high, can be provided. Moreover, a control system high in responsiveness and stability can be designed by changing the magnitude of the respective gains of the proportion factor and the integration element by the value of an encoder cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer for driving a DC motor to print on a recording medium.

[0002]

2. Description of the Related Art FIG. 9 shows a carriage mechanism of a serial printer to which the present invention is applied. The rotary motion of the DC motor 1 is converted into a linear motion of the timing belt 3 via the pulley 2. By pulling with the timing belt 3, the carriage 5 carrying the print head 4 is moved, and printing is performed from the print head 4 to the print medium 8 such as paper. An encoder 6 is provided in the DC motor 1, and each time a reference edge (for example, a rising edge) of the encoder pulse occurs, its cycle is measured to detect the rotation speed.

Conventionally, as a method for controlling the rotation speed of the DC motor 1, there is a method disclosed in Japanese Utility Model Laid-Open No. 62-169811. This is a control method when a general P-I compensator configured by the block diagram of FIG. 10 is used, and the proportional element 2 of the gain Kp is
The compensator 22 is a combination of 0 and the integral element 21 of the gain Ki in parallel, and is calculated and output from the compensator 22 according to the deviation Err between the period T of the encoder pulse and the target period Tref (corresponding to the target rotation speed). It is a method of matching the rotation speed of the DC motor 1 with the target rotation speed by controlling the control amount.

[0004]

The conventional method can be realized relatively easily by executing the processing procedure program on the CPU. However, every time the reference edge of the encoder occurs, the deviation Err with respect to the target cycle is calculated, and the deviation Err
Igain of the integral and the gain Ki of the integral element and its cumulative value Iout
And the product P of the deviation Err and the gain Kp of the proportional element
A long processing time is required because a series of calculations are performed, in which out is obtained and the control amount is determined by obtaining the sum of Pout and Iout. For this reason, when the target rotation speed of the DC motor is increased and the encoder cycle is shortened, there is a problem that the arithmetic processing cannot be supported and the control accuracy is deteriorated.

Further, since the gains of the integral element and the proportional element are fixed values, it is difficult to design a control system having both high responsiveness and stability.

The present invention has been made in view of the above points and solves such a problem. An object of the present invention is to shorten the processing time for calculating the control amount output from the P-I compensator, and to improve the responsiveness and stability. By providing both of the above, the DC motor control device with high control accuracy, which is optimum for the printer, is provided.

[0007]

In order to achieve this object, the printer control apparatus of the present invention uses a value obtained by multiplying the deviation from the target rotation speed and the gain of the integral element in advance in accordance with the rotation speed of the DC motor. A first storage means for storing, and a second storage means for storing in advance a value obtained by multiplying the deviation from the target rotation speed by the gain of the proportional element in correspondence with the rotation speed of the DC motor.
Storage means and speed detection means for detecting the rotation speed of the DC motor, and are stored in the first storage means and the second storage means according to the rotation speed detected by the speed detection means. The first feature is that the output value of the P-I compensator is calculated using the present value, and the first storage means and the second storage means are provided for different target rotation speeds. This is the second feature.

[0008]

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

FIG. 1 is a control block diagram for controlling a carriage mechanism of a serial printer which is an embodiment of the present invention. The configuration of the carriage control device of the serial printer is the same as in FIG. In FIG. 1, reference numeral 10 is a CPU that controls the carriage control device, and
Processing described later is performed according to the control program written in M11. In the present embodiment, in addition to the control program, the ROM 11 stores two types of data tables corresponding to the cycle T of the encoder pulse output from the encoder 6. Reference numeral 12 is an R for temporarily storing various data.
AM. Print data from a host device 13 such as a computer is sent to the CPU 10 via an I / F unit (interface unit) 14. The print command is sent to the head drive unit 16 via the I / O unit 15, and in response to this, the head drive unit 16 drives the print head 4 to perform printing. The control signal of the DC motor 1 is sent to the DC motor driving unit 17 via the I / O unit 15 to drive the DC motor 1. An encoder 6 is provided in the DC motor 1, and every time a reference edge (a rising edge in this embodiment) of an encoder pulse occurs, its cycle is measured to detect the rotation speed.

The control method is the PWM method. As shown in FIG. 2, this is a system in which the duty Tduty for a certain fixed period Tpwm is changed and the DC motor 1 is driven by using this as a control signal. The control amount determined from the processing procedure described later corresponds to this duty Tduty. That is, the control signal has a certain duty cycle Tduty.
It is a pulse train with. The DC motor 1 is driven by using this as the base signal of the transistor of the DC motor drive unit 17 shown in detail in FIG. Transistor in FIG.
By giving an ON control signal to the bases of Tr1 and transistor Tr4, the rotation direction becomes CW, and by giving an ON control signal to the bases of transistor Tr2 and transistor Tr3, the rotation direction becomes CCW.

[0011]

[Table 1]

[0012]

[Table 2]

The data tables shown in Tables 1 and 2 will be described in more detail. In the data table shown in Table 1, the cycle T and the integral element calculation value Igain are shown in FIG.
There is a relation shown in, and this is expressed by equation (1).

Igain = Ki × (T−Tref) T1>T> T11 (1) where Ki is the gain of the integration element 21 shown in FIG.
Tref is a target period corresponding to the target rotation speed. The second term (T-Tref) on the right side is the deviation Err with respect to the target period Tref. That is, a value obtained by multiplying the deviation Err with respect to the target period Tref and the gain Kp of the integral element in correspondence with each encoder period T is stored in advance. Note that T> T
In the range of 1 and T <T11, Igain is a constant value.

In the data table shown in Table 2, the cycle T and the proportional element calculation value Pout have the relationship shown in FIG. 5, which is expressed by the equation (2).

Pout = Kp × (T−Tref) T1>T> T11 (2) where Kp is the gain of the proportional element 20 shown in FIG. That is, the deviation Err with respect to the target cycle Tref and the gain K of the proportional element corresponding to each encoder cycle T
The value multiplied by p is stored in advance. Note that Pout is a constant value in the range of T> T1 and T <T11.

The operation of the embodiment of the present invention configured as described above will be described with reference to FIG. FIG. 6 is a flowchart until the control amount Tduty according to the cycle T is determined.

When the CPU 10 recognizes the reference edge of the encoder signal via the I / O unit 15, the cycle T is measured.
[Step] Next, n-th (n = 1, 2,
...), the integral element calculation value Igain corresponding to the period T of the encoder pulse generated is drawn from the data table of Table 1, and the cumulative value Iout is calculated by the equation (3) to obtain C.
Store in a register in PU. [Step]

[0019]

[Equation 1]

Further, the proportional element calculation value Pout corresponding to the cycle T is drawn from the data table of Table 2, and [step] the control amount Tduty is calculated by the equation (4). [Step] Tduty = Pout + Iout (4) Each time the reference edge of the encoder occurs, the control amount Tduty is determined from step to step.

As described above, according to this embodiment, the value obtained by multiplying the deviation Err with respect to the target period Tref by the encoder period T and the respective gains of the integral element and the proportional element is stored in advance. Deviation Er with respect to period Tref
The calculation of the product of r, the deviation Err and the gain Ki of the integral element, and the product of the deviation Err and the gain Kp of the proportional element is unnecessary. Therefore, it is possible to shorten the processing time until the control amount Tduty is determined.

Next, a second embodiment of the present invention will be described. In the present embodiment, the cycle T and the integral element calculation value Igain have the relationship shown in FIG. 7, which is expressed by the equation (5).

[0023]

[Equation 2]

Further, there is a relationship shown in FIG. 8 between the period T and the proportional element calculation value Pout, which is expressed by the equation 6.

[0025]

[Equation 3]

The other configuration and processing procedure are the same as those in the first embodiment. According to this embodiment, the encoder cycle T
Since the magnitudes of the gains of the proportional element and the integral element are changed by, the control system having both high responsiveness and stability can be designed.

In the printer, it is general that there are a plurality of target rotation speeds depending on the print mode. In this case, a data table is set as shown in Tables 3 and 4 for each target speed.

[0028]

[Table 3]

[0029]

[Table 4]

Since the encoder cycle T differs depending on the target rotation speed, the data is set by changing the interval width of the cycle T on the data table in order to secure the relative control accuracy with respect to the target rotation speed. Further, when the target rotation speed is low and the sampling cycle of the rotation speed by the encoder is reduced, the data setting area of the data table is enlarged to secure the control accuracy. In this way, an optimum control system can be designed for each print mode.

[0031]

As described above, according to the present invention, a value obtained by multiplying the deviation with respect to the target period and the gains of the proportional element and the integral element corresponding to the encoder period is stored in advance as a control data table. The processing time until the control amount is determined can be shortened. Therefore, even when the target rotation speed is high, the processing time can be dealt with, and a high control accuracy can be ensured even in a printer with a high printing speed. Further, by changing the magnitudes of the gains of the proportional element and the integral element depending on the value of the encoder period, it is possible to design a control system having both high responsiveness and stability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of control signals according to the embodiment of this invention.

FIG. 3 is a DC motor drive circuit diagram of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a relationship between a cycle and an integral element calculation value according to the embodiment of this invention.

FIG. 5 is an explanatory diagram of a relationship between a cycle and a proportional element calculation value according to the embodiment of this invention.

FIG. 6 is a flowchart illustrating a control procedure according to the embodiment of this invention.

FIG. 7 is an explanatory diagram of a relationship between a cycle and an integral element calculation value according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a relationship between a cycle and a proportional element calculation value according to another embodiment of the present invention.

FIG. 9 is a configuration diagram of a printer of the present invention.

FIG. 10 is an explanatory diagram of a PI compensator.

[Explanation of symbols]

 1 DC Motor 2 Pulley 3 Timing Belt 4 Print Head 5 Carriage 6 Encoder 8 Print Medium 10 CPU 11 ROM 12 RAM 13 Host Device 14 I / F Unit 15 I / O Unit 16 Head Drive Unit 17 DC Motor Drive Unit 20 Proportional Element 21 Integral element 22 PI compensator

Claims (2)

[Claims] 1. A printer for controlling a direct current motor using a P-I compensator, wherein a value obtained by multiplying a deviation from a target rotational speed by a gain of an integral element is corresponding to a value of the rotational speed of the direct current motor in advance. First storage means for storing; second storage means for storing in advance a value obtained by multiplying a deviation with respect to a target rotation speed by a gain of a proportional element corresponding to a value of the rotation speed of the DC motor; And a speed detection means for detecting the rotation speed of the first storage means and the second storage means according to the value of the rotation speed detected by the speed detection means. A printer control device characterized by calculating an output value of a PI compensator. 2. The printer control device according to claim 1, wherein the printer control device includes the first storage means and the second storage means for a plurality of different target rotation speeds.