JP3414726B2 - Serial printing device - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention is by the direct current motor
The print carriage to reciprocate a recording medium relating to the row of the Hare printing device. FIG. 9 shows a carriage mechanism of a serial printer to which the present invention is applied. The rotational movement of the DC motor 1 is converted into a linear movement of the timing belt 3 via the pulley 2. The carriage 5 on which the print head 4 is mounted is moved by being pulled by the timing belt 3, and printing is performed from the print head 4 on a print medium 8 such as paper. The DC motor 1 is provided with an encoder 6, and each time a reference edge (for example, a rising edge) of an encoder pulse is generated, its cycle is measured to detect a rotation speed. Conventionally, as a method of controlling the rotation speed of the DC motor 1, there is Japanese Utility Model Laid-Open No. Sho 62-169811. This is a control method using a general PI compensator constituted by the block diagram of FIG. 10, and compensates for a combination of a proportional element 20 of gain Kp and an integral element 21 of gain Ki in parallel. And the period T of the encoder pulse
Err between the error and target cycle Tref (corresponding to target rotation speed)
In this method, the rotational speed of the DC motor 1 is made to coincide with the target rotational speed by a control amount calculated and output from the compensator 22 in accordance with the following equation. [0004] In the conventional method, since the gain of the integral element, the proportional element, and the differential element is a fixed value,
There is a problem that it is difficult to design a control system having high responsiveness and stability. In view of the above, the present invention has been made to solve such a problem. By improving both responsiveness and stability, a DC motor for controlling a carriage can be controlled with high accuracy.
It is intended to provide a printing device which can be controlled . [0006] To achieve the above object.
Therefore, in the present invention, print data is output from the host.
Carriage that receives force and is driven back and forth by a DC motor
Printing that prints using the recording head mounted on the printer
In the device, a speed detecting means for detecting a rotational speed of the DC motor, the rotation speed of the detected direct current motor
A calculated value obtained by multiplying the deviation from the target speed by the gain of the integral element ,
And the detected rotational speed and target speed of the DC motor.
Wherein each of the calculated value with the deviation between degree and deviation corresponding to the rotational speed of the DC motor multiplied by the gain of the proportional element DC motor
A storage means for storing in advance for each rotational speed of over motor, the straight
Based on the rotation speed of the flow motor and the deviation.
Gain setting means for reading the operation value of the stage.
I made it. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a control block diagram for controlling a carriage mechanism of a serial printer according to one embodiment of the present invention. The configuration of the carriage control device of the serial printer is the same as that of FIG. In FIG. 1, reference numeral 10 denotes a CPU for controlling the carriage control device.
The processing described below is performed according to the control program written in M11. In the present embodiment, the ROM 11 stores two types of data tables corresponding to the cycle T of the encoder pulse output from the encoder 6 in addition to the control program. Reference numeral 12 denotes 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 the head drive unit 16 drives the print head 4 to perform printing in response thereto. The control signal of the DC motor 1 is sent to the DC motor drive unit 17 via the I / O unit 15 to drive the DC motor 1. Note that the DC motor 1 is provided with an encoder 6, and each time a reference edge (a rising edge in the present embodiment) of an encoder pulse is generated, its cycle is measured to detect a rotation speed. The control system is a PWM system. In this method, as shown in FIG. 2, the duty Tduty for a certain period Tpwm is changed, and this is used as a control signal to drive the DC motor 1. The control amount determined from the processing procedure described later corresponds to this duty Tduty. That is, the control signal has a certain duty Tduty
Is a pulse train with. This is used to drive the DC motor 1 as a base signal of the transistor of the DC motor drive unit 17 shown in detail in FIG. In FIG. 3, the transistor T
By applying an ON control signal to the base of the transistor r1 and the transistor Tr4, the rotation direction becomes CW,
By providing an ON control signal to r2 and the base of the transistor Tr3, the rotation direction becomes CCW. [Table 1] [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 period T and the integral element operation value Igain are shown in FIG.
And this is represented 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 cycle corresponding to the target rotation speed. The second term (T-Tref) on the right side is a deviation Err from the target cycle Tref. That is, a calculated value obtained by multiplying the deviation Err with respect to the target period Tref by the gain Kp of the integral element is stored in advance corresponding to each encoder period T. Note that T
Igain is a constant value in the range of> T1 and T <T11. In the data table shown in Table 2, the period T and the proportional element operation value Pout have a relationship shown in FIG. 5, which is expressed by 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 period Tref and the gain Kp of the proportional element correspond to each encoder period T.
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, it measures the period T (step). Next, an integral element operation value Igain corresponding to the cycle T of the encoder pulse generated n-th (n = 1, 2,...) Since the start of the PI control is extracted from the data table of Table 1. According to equation (3), the accumulated value I
out is calculated and stored in a register in the CPU [step]. ## EQU1 ## Further, a proportional element operation value Pout corresponding to the cycle T is extracted from the data table shown in Table 2, and a [step] control amount Tduty is calculated by the equation (4). [Step] Tduty = Pout + Iout (4) Every time a reference edge of the encoder occurs, the control amount Tduty is determined in a step-by-step procedure. As described above, according to the present embodiment, the calculated value obtained by multiplying the deviation Err with respect to the target period Tref by the gain of each of the integral element and the proportional element corresponding to the encoder cycle T is stored in advance. It is unnecessary to calculate the deviation Err with respect to the target period Tref, the product of 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. For this reason, the processing time required to determine the control amount Tduty can be reduced. Next, a second embodiment of the present invention will be described. In the present embodiment, the period T and the integral element operation value Igain have a relationship shown in FIG. 7, which is expressed by equation (5). ## EQU2 ## The relationship between the period T and the proportional element operation value Pout is shown in FIG. [Equation 3] Other configurations and processing procedures are the same as those of the first embodiment. According to the present embodiment, the encoder cycle T
Since the magnitudes of the respective gains of the proportional element and the integral element are changed, a control system having high responsiveness and high stability can be designed. In general, a printer has 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 of the target speeds. [Table 3] [Table 4] Since the encoder cycle T differs depending on the target rotation speed, in order to ensure relative control accuracy with respect to the target rotation speed, data is set by changing the section width of the cycle T on the data table. When the target rotation speed is low and the sampling period of the rotation speed by the encoder decreases, the data setting area of the data table is enlarged to ensure control accuracy. In this way, an optimal control system can be designed for each print mode. Further, in the above embodiment, the PI control is described as an example, but it is clear that the present invention is applicable to the PID control. 4, 5, 7, and 8
In the above, the relationship between the first operation value multiplied by the gain of the proportional element and the second operation value multiplied by the gain of the integral element and the rotation speed of the DC motor has been described. It is obvious that the gain, the gain of the differential element, and the rotation speed of the DC motor have the same relationship. Further, in FIGS. 4, 5, 7, and 8, the rotation speed of the DC motor is different from the first calculation value multiplied by the gain of the proportional element and the second calculation value multiplied by the gain of the integration element. The data is not limited to a linear relationship, and data may be set in the data table as a non-linear relationship as appropriate. As described above, according to the present invention, according to the rotation speed of the DC motor, the gain of the proportional element and the integral
The calculated value of the elementary gain and deviation is stored in the storage means in advance.
And read from the storage means, the deviation and the gay of each element
Operation process with the controller becomes unnecessary, and the burden on the control processor is reduced.
Can be reduced, and the printing operation can be optimized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an explanatory diagram of a control signal according to the embodiment of the present invention. FIG. 3 is a DC motor drive circuit diagram according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing a relationship between a cycle and an integral element operation value according to the embodiment of the present invention. FIG. 5 is an explanatory diagram illustrating a relationship between a cycle and a proportional element calculation value according to the embodiment of the present invention. FIG. 6 is a flowchart illustrating a control procedure according to the embodiment of the present invention. FIG. 7 is an explanatory diagram illustrating a relationship between a cycle and an integral element operation value according to another embodiment of the present invention. FIG. 8 is an explanatory diagram illustrating a relationship between a period and a calculated value of a proportional element according to another embodiment of the present invention. FIG. 9 is a configuration diagram of a printer according to the invention. FIG. 10 is a diagram illustrating a PI compensator. [Description of Signs] 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 Part 20 proportional element 21 integral element 22 PI compensator

Continuation of the front page (56) References JP-A-3-78479 (JP, A) JP-A-3-3688 (JP, A) JP-A-61-94104 (JP, A) JP-A-61-196786 (JP) , A) Japanese Patent Publication No. 52-12349 (JP, B1) WO 91/004866 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/00-5/26 H02P 7 / 00-7/34 B41J 19/30

Claims (1)

(57) [Claim 1] In a serial printing apparatus which receives output of print data from a host and performs printing with a recording head mounted on a carriage reciprocally driven by a DC motor, Speed detection means for detecting a rotation speed, a calculated value obtained by multiplying a deviation between the detected rotation speed of the DC motor and the target speed by a gain of an integral element, and a rotation speed and a target speed of the detected DC motor Storage means for storing, in advance, for each of the DC motor rotational speeds, a deviation of the DC motor rotational speed and a calculation value obtained by multiplying the deviation by the gain of the proportional element, and the DC motor rotational speed and the deviation. And a gain setting means for reading out the operation value of the storage means based on the above.