JP2508667B2 - Printing speed control method for serial printer - Google Patents

Description

The present invention relates to a carriage driven by a DC motor and reciprocating along a platen, and a carriage moving speed of a serial printer having a print head mounted on the carriage. That is, the present invention relates to a printing speed control method.

(Prior Art) FIG. 6 is a plan view showing a configuration of a serial printer. In the figure, reference numeral 61 denotes a platen, which is rotated around an axis of the platen by a step motor (not shown) to feed the print paper wound around the platen. 62 is a side plate, 63 is a shaft fixed to the side plate 62, 64 is a carriage movably attached to the shaft 63, and 65 is a print head mounted on the carriage 64. A DC motor (not shown) is connected to the carriage 64 via a wire, a belt or a gear. this
The rotation of the DC motor causes the print head 65 to move integrally with the carriage 64 along the platen 61 on the shaft 63 and perform printing. Although not shown, a slit disk is attached to the rotary shaft of this DC motor as a means for speed detection and position detection, and a photo sensor converts the rotation of the slit disk into an electric signal and sends it to a control circuit. .

Conventionally, the control method of the moving speed of the carriage of the serial printer, that is, the printing speed as described above has been performed by the feedback loop as shown in FIG. In this figure, in this method, first, the adder calculates the addition by inverting the sign of the command value C and the speed S detected by the speed detector. Then, the calculation result is amplified by the amplifier and given to the DC motor, and the rotation speed of the DC motor, that is, the moving speed of the carriage is controlled to be constant.

Here, if the target moving speed of the carriage is v ₀ , the dynamic friction of the carriage is F, and the gain of the amplifier is G, then (C−v ₀ ) × G = F. The command value C becomes C = F / G + v ₀ , which is a value larger than the target moving speed v ₀ by F / G. If gain G is made sufficiently large, F / G becomes a negligible value, and C = v ₀ can be set. However, as gain G is increased, the circuit system becomes unstable and vibrates. Out of control. Therefore. F / G cannot be ignored even if the maximum gain G that the circuit system operates stably is selected. Therefore, in order to determine the command value C, conventionally, a method of giving various command values to a large number of printers for printing and statistically selecting the command value that achieves the printing speed closest to the target speed has been adopted. It was

(Problems to be Solved by the Invention) However, in the above-described conventional method, the dynamic friction F is different due to the dimensional error of the carriage, the shaft supporting the carriage, and the like for each of the large number of printers used to determine the command value. The rotation speed of the DC motor, that is, the moving speed of the carriage, varies from printer to printer, and there is a problem in that the desired printing speed cannot be obtained.

The present invention is intended to solve these problems, and an object of the present invention is to provide a printing speed control method for a serial printer that can secure a desired printing speed.

(Means for Solving Problems) In order to solve the above problems, the present invention relates to a serial printer having a carriage driven by a DC motor and reciprocating along a platen, and a print head mounted on the carriage. In, the average value of the current supplied to the DC motor was calculated while the carriage was operating at the constant speed during the home search operation of the print head immediately after the serial printer was powered on. The step of determining the current offset amount of the DC motor based on this average value and the subsequent current friction amount generated in the above step are supplied to the DC motor during the normal printing operation, which is accompanied by the dynamic friction generated by the movement of the carriage. It is a method including a step of controlling fluctuations in printing speed.

(Operation) According to the method of the present invention including the above steps, immediately after the power of the serial printer is turned on, the print head of the serial printer performs the origin of the printing position required for the printing operation. During this operation, while the carriage is performing the constant speed operation, the average value of the current supplied to the DC motor is calculated, and the current offset amount of the DC motor is determined based on this average value. Then, during the subsequent normal printing operation, the current offset amount is supplied to the DC motor. As a result, the fluctuation of the printing speed due to the dynamic friction generated by the movement of the carriage is controlled.

Therefore, the present invention can solve the above problems and provide a printing speed control method for a serial printer that can secure a desired printing speed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

First, a system for controlling the rotation speed of the DC motor of the serial printer will be described.

FIG. 2 is a block diagram showing a rotation speed control system of a DC motor of a serial printer. In the figure, the control CPU 1 has a ROM 2 for storing a control program via a bus 9, a RAM 3 for storing control information, a digital value instructed to the CPU 1 is converted into a current, and a DC motor 6 is driven. For this purpose, a speed detection circuit 5 for measuring the time interval of the change of signals from the DA converter 4 and the photo sensor 8 is connected.

In such a system configuration, the CPU 1 performs arithmetic processing corresponding to the operation of the circuit shown in FIG. 1 showing an embodiment of the present invention. That is, as will be described later, when the origin of the printing position is set immediately after the power is turned on, and the dynamic friction of the carriage is automatically measured while the carriage is operating at a constant speed, the measured dynamic friction is calculated. By applying a corresponding current to the DC motor as a dynamic friction offset amount, variations in speed are eliminated.

Next, a method of measuring the dynamic friction of the serial printer will be described.

First, this dynamic friction measurement is performed when the origin of the printing position is set immediately after the power of the printer is turned on. As can be seen from FIGS. 3 (a) and 3 (b) showing the movement of the carriage equipped with the print head and the displacement of its movement speed when the origin is set, a predetermined distance is moved at a target speed which is a predetermined constant speed. During that time, the values written in the DA converter are averaged to obtain the dynamic friction offset amount. That is, this dynamic friction offset amount is a value written in the DA converter for giving a force that balances the dynamic friction to the DC motor, instead of obtaining the dynamic friction in units of force.

A method of calculating the dynamic friction offset amount will be described with reference to the flowchart shown in FIG. It is assumed that all the registers described later are in the RAM 3 shown in FIG.

First, in step 101, the TOTAL register for obtaining the average of the values written in the DA converter 4 of FIG. 2 is cleared as an initial setting. Next, in step 102, the second pulse is measured by measuring the pulse interval from the photo sensor 8 of FIG.
The speed data is read from the speed detection circuit 5 in FIG. 2 which detects the speed of the DC motor 6 in the figure, the difference from the target speed is calculated in step 103, and the difference is written in the speed difference register in the RAM 3. In step 104, the value obtained by multiplying the speed difference by the gain is
Write to DA converter 4 in the figure. From step 2 to step 4, the speed control of the motor is performed by the same method as the conventional method. Further, in step 105, the value written in the DA converter 4 in FIG. 2 is added to the TOTAL register. As a result of repeating the processes from step 102 to step 105 N times, the total sum of the values written in the DA converter 4 in FIG. 2 is stored in the TOTAL register. This total is divided by the number of times of sampling N in step 107 to obtain an average value, which is written in the dynamic friction offset register.

Speed control, which will be described later, is performed according to the contents of the dynamic friction offset register thus determined.

Next, the content of the dynamic friction offset register calculated by the above calculation method, that is, the speed control method at the time of printing using the dynamic friction offset amount will be described with reference to the flowchart shown in FIG.

First, in step 201, speed data is read from the speed detection circuit 5 of FIG. 2, and in step 202 the difference from the target speed is calculated and written in the speed difference register. In step 203, a value obtained by multiplying the speed difference by the gain is obtained. Then, at step 204, the dynamic friction offset amount obtained by the above method is added to the product obtained at step 203, and the added value is written to the DA converter 4 of FIG. 2 at step 205.

Therefore, the dynamic friction offset amount obtained by the above method is added to the output of the amplifier shown in FIG. 1 to control the rotation speed of the DC motor shown in FIG. 1, that is, the carriage moving speed to be constant.

(Effect of the Invention) As described above, according to the present invention, the offset amount of the DC motor that absorbs the variation in the dynamic friction due to the dimensional error of the carriage or shaft of the printer is determined to control the rotation speed of the DC motor. As a result, it is possible to provide a printing speed control method for a serial printer that can secure a desired printing speed for each printer.

[Brief description of drawings]

1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a rotation speed control system of a DC motor of a serial printer, FIG. 3 is a diagram showing movement of a print head and displacement of the movement speed, FIG. 4 is a flow chart showing a procedure for calculating the dynamic friction offset amount, FIG. 5 is a flow chart showing a print speed control procedure at the time of printing, FIG. 6 is a plan view showing the configuration of the serial printer, and FIG. 7 is a conventional print speed. It is a circuit diagram which shows a control circuit. 61 …… Platen, 62 …… Side plate, 63 …… Shaft, 64 …… Carriage, 65 …… Print head.

Claims (1)

(57) [Claims] 1. A serial printer having a carriage driven by a DC motor and reciprocating along a platen, and a print head mounted on the carriage, wherein printing of the print head is performed immediately after power-on of the serial printer. While the carriage is performing a constant speed operation in the position origin operation, the average value of the current supplied to the DC motor is calculated, and the DC value is calculated based on the average value.
The current offset amount of the motor is determined, and during the subsequent printing operation, the current offset amount is supplied to the DC motor to control the fluctuation of the printing speed due to the dynamic friction generated by the movement of the carriage. Print speed control method for serial printer.