JP2988126B2 - Carriage control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 1 shows a configuration of a carriage control device of a serial printer to which the present invention is applied. DC motor 1
Is converted into a linear motion 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 for position detection.

FIG. 7A shows a driving pattern of the DC motor 1 when printing one line of print data using the apparatus shown in FIG. 1 and FIG. 7B shows a current flowing through the DC motor 1 at this time. ). Tacc is an acceleration section. After reaching the target rotation speed, printing is performed in the section of Tconst while performing constant speed control. After printing is completed, deceleration control is started and deceleration is performed in the section of Tbrk. The acceleration and deceleration of the carriage 5 requires a large torque, and the generated torque is proportional to the current value of the DC motor 1. Therefore, as shown in FIG. Becomes larger. For this reason, the shorter the constant speed control section Tconst, the larger the average current value of the DC motor 1 per line becomes.
The heat value of the DC motor 1 increases as the average current value increases. When such printing is performed continuously,
The amount of heat generated by the DC motor 1 increases excessively and exceeds the allowable temperature,
There is a risk of burning. Therefore, a conventional printer uses a high-output DC motor in consideration of a case where print data in one line is small.

[0004]

However, the number of print data in one line is generally about several tens of digits, and for example, it is rare that the print of less than ten digits continues continuously for a long time. Selecting a high-output DC motor on the assumption of a special situation as described above has a problem in that the utilization efficiency is reduced. The present invention has been made in order to solve such a problem, and an object of the present invention is to control a heating temperature so as not to exceed an allowable value, thereby improving a use efficiency of a DC motor. It is to provide a control device.

[0005]

In order to solve such a problem, a carriage control device according to the present invention comprises a response characteristic detecting means for detecting a response characteristic of the DC motor, and a position detecting means for detecting a position of the carriage. Means for determining whether the response distance detected by the response characteristic detecting means reaches a predetermined value and the moving distance of the carriage required for printing one line is shorter than the predetermined moving distance. The correction is made to a value equal to the distance or to a value larger than the predetermined traveling distance.

[0006]

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

FIG. 2 is a control block diagram for controlling the carriage control device of FIG. In FIG. 2, reference numeral 10 denotes a CPU for controlling the printer. Reference numeral 11 denotes a ROM, which is a DC motor 1 in this embodiment in addition to the control program.
Limit time Ts (20 msec in this embodiment) until the vehicle reaches the predetermined rotation speed, and the predetermined travel distance Ss at that time.
(In this embodiment, 150 pulses). 12
Is a RAM for temporarily storing various data. 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 1 via the I / O unit 15.
6, the head driving unit 16 drives the print head 4 to perform printing. A control command for the DC motor 1 that drives the carriage 5 is sent to the DC motor drive unit 17 via the I / O unit 15, and the DC motor drive unit 17 drives the DC motor 1 to control it to a target rotation speed. The value of the target rotation speed is stored in the RAM 12. The output pulse of the encoder 6 according to the rotation angle of the DC motor 1 is transmitted to the I / O unit 1
The position of the carriage 5 is managed by counting the number of pulses, and the rotation speed is detected by measuring the period. Hereinafter, the moving distance of the carriage 5 is represented by the number of pulses of the encoder. 7
Is a timer, which counts time based on data set by the CPU 10. When the time measurement ends, the timer 7 generates an interrupt signal, and the CPU 10 recognizes the end of the time measurement.

The operation of the embodiment of the present invention configured as described above will be described with reference to FIG. FIG. 3 is a flowchart showing an operation of printing one line of print data. Here, from the state where the carriage 5 is stopped at the position shown in FIG.
BCD "is printed. First, the CPU 1
0 expands the head drive data in the RAM 12 according to the print data from the host device 13 and calculates a print area corresponding to the print data. At this time, the distance Spe from the stop position of the carriage 5 to the print end position (the last position of the print area) is determined. Here, Spe = 100 pulses (step). In the step, first, the DC motor 1 is driven to start the movement of the carriage 5, and at the same time, the data of the allowable limit time Ts is set in the timer 7. In this embodiment, 20 msec is set. In the step, it is checked whether the rotation speed of the DC motor 1 has reached the responsiveness check rotation speed Vcheck by measuring the period of the output pulse of the encoder 6, and an interrupt signal of the timer 7 is generated until the rotation speed reaches Vcheck. If not, go to step. In the step, the deceleration start distance Sb is set to the value of Spe determined in the step (Sb = Spe = 100 pulses). The deceleration start distance Sb is a travel distance from the stop position of the carriage 5 to the start of deceleration control after printing is completed. On the other hand, if the interruption signal of the timer 7 is generated before reaching Vcheck in the step, the process proceeds to the step. In the step, the predetermined traveling distance Ss stored in the ROM 11 is compared with the distance Spe from the stop position of the carriage 5 determined in the step to the printing end position, and if the Spe is longer than the predetermined traveling distance Ss, the process proceeds to the step. In the step, the distance Spe from the stop position of the carriage 5 to the printing end position is equal to the predetermined traveling distance Ss
Go to step if: In the step, the deceleration start distance Sb is set to the value of the predetermined traveling distance Ss (Sb = Ss). When the deceleration start distance Sb, which is the travel distance from the stop position of the carriage 5 to the start of deceleration control after printing is completed, is determined, the process proceeds to step. In the step, when the print area is reached while controlling the DC motor 1 at the target rotation speed, the CPU 10 drives the print head 4 based on the head drive data to perform printing. When the printing according to the print data is completed, the process proceeds to the step. In the step, it is determined whether or not the moving distance of the carriage 5 has reached the step or the value of Sb set in the step. Carriage 5
When the vehicle travels for Sb, the process proceeds to the step. In the step, the carriage 5 is stopped by performing deceleration control. The above is the operation for printing one line of print data.

Next, a method of determining the set value of the predetermined traveling distance Ss will be described. As described above, the energizing current of the DC motor 1 increases during acceleration and deceleration and decreases during constant speed control.
Therefore, the shorter the distance Spe from the stop position of the carriage 5 to the printing end position, the larger the average value of the energizing current per line becomes, so that the heat generation temperature of the DC motor 1 becomes higher. FIG. 5A shows the relationship between the length of Spe and the heat generation saturation temperature of the DC motor 1 when printing is continuously performed with the distance Spe from the stop position of the carriage 5 to the printing end position in one line being constant. For example, when the distance Spe from the stop position of the carriage 5 to the printing end position is 150 pulses, the heat generation saturation temperature of the DC motor 1 is 130 ° C. If the allowable heat generation temperature of the DC motor 1 is 130 ° C., Spe
However, there is a risk that the DC motor 1 may be burned out due to heat generation in a continuous printing operation of 150 pulses or less. Therefore, the allowable heat generation temperature Hs is set to 130 ° C., and the predetermined traveling distance Ss is set to 150 pulses. This can be obtained in advance by an experiment.

Next, a method of determining an allowable limit time Ts until the DC motor 1 reaches the responsiveness confirmation rotation speed Vcheck will be described. In general, the current-torque characteristics of the DC motor 1 decrease with an increase in the heat generation temperature, and the time required to reach a predetermined speed becomes slow.
There is a correlation as shown in FIG. Since the time required for the DC motor 1 used in the present embodiment to reach the responsiveness check rotation speed Vcheck when the allowable limit temperature Hs = 130 ° C. is 20 msec from FIG. 6, the allowable limit time Ts is set to 20 msec. doing.

With the above configuration and operation, in the printing operation when the time to reach Vcheck is shorter than 20 msec (that is, the heat generation temperature of the DC motor 1 is lower than the allowable limit temperature Hs according to the relationship of FIG. 6), Immediately after completion, deceleration control is performed to secure high-speed printing. The carriage operation at this time is shown in FIG. The horizontal axis represents the moving distance, and the vertical axis represents the moving speed. On the other hand, the time required to reach Vcheck is 20 msec or more (that is, the heat generation temperature of the DC motor 1 has reached the allowable limit temperature Hs), and the distance Spe from the stop position of the carriage 5 to the printing end position is the predetermined travel distance Ss If it is smaller, the deceleration start distance Sb is set to the value of the predetermined traveling distance Ss, and the time (distance) of the constant speed traveling is set.
, The exothermic temperature is reduced to the allowable exothermic temperature Hs.
It is possible to suppress to below. FIG. 4C shows the carriage operation at this time. As a result, the heating saturation temperature of the DC motor 1 in a case where printing is continuously performed with the distance Spe from the stop position of the carriage 5 to the printing end position being constant is as shown in FIG. In this embodiment, the deceleration start distance Sb is set to the value of the predetermined traveling distance Ss (Sb =
Ss), but when controlling to a temperature lower than the allowable heat generation temperature Hs, for example, the deceleration start distance Sb may be set to a value larger than the predetermined traveling distance Ss. By increasing the time of the constant-speed running, the effective printing speed as a printer is reduced. However, as can be seen from FIG. 5B, in the printing with Spe of 150 pulses or more, continuous printing can be performed without increasing the time of the constant-speed running. Printing operation is possible. As described above, it is rare that printing with a small number of print digits continues for a long time, and a print digit with a high use frequency can be configured without lowering the effective printing speed. Even if printing with a small number of print digits continues, if the temperature is within the allowable heat generation temperature Hs, the deceleration control is started immediately after printing is completed, so that the effective printing speed does not decrease. In general, a printer has a plurality of print modes having different print densities, and the print speed (carriage speed) differs depending on each print mode. Therefore, since the current supplied to the DC motor 1 also differs depending on the printing mode, the relationship between the printing mode and the predetermined traveling distance Ss is stored in the ROM 11 as shown in Table 1, and the predetermined traveling distance Ss is stored in accordance with the printing mode. It can be handled by changing the value.

[0012]

[Table 1]

In Table 1, the lower the carriage speed, the smaller the average current per line of the DC motor 1 is.
In, the predetermined traveling distance Ss is set to a smaller value as the carriage speed is lower. In the present embodiment, the deceleration start distance Sb, which is the travel distance from the stop position of the carriage before the start of printing to the start of deceleration control after printing, is used as the movement distance of the carriage required for printing one line. In addition, the travel distance from the stop position of the carriage before the start of printing to the stop position after the end of printing, or the travel distance during constant speed control can be used. Further, if the traveling pattern is determined, the traveling distance and the traveling time have a corresponding relationship, and therefore, the traveling time may be used instead of the traveling distance. In this embodiment, the acceleration characteristic is detected as the response characteristic of the DC motor. However, the deceleration characteristic from a predetermined speed may be detected. Furthermore, it seems that the present invention can be applied to other than the printer as an application.

[0014]

As described above, according to the present invention, it is possible to control the calorific value of the DC motor so as not to exceed the allowable value with a simple configuration, and to provide a carriage control device with high utilization efficiency. I can do it.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a printer showing one embodiment of the present invention.

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is a flowchart illustrating a carriage operation according to an embodiment of the present invention.

FIG. 4 is a diagram showing a carriage driving operation according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating a heat generation state of a DC motor.

FIG. 6 is a view for explaining the relationship between the heat generation temperature of a DC motor and response characteristics.

FIG. 7 is a diagram showing a carriage drive pattern and a current supplied to a DC motor.

[Explanation of symbols]

 Reference Signs List 1 DC motor 2 Pulley 3 Timing belt 4 Print head 5 Carriage 6 Encoder 7 Timer 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

Claims (1)

(57) [Claims] 1. A carriage control device having a carriage on which a print head is mounted, and a DC motor for driving the carriage, a response characteristic detecting means for detecting a response characteristic of the DC motor, and a position for detecting a position of the carriage. When the result detected by the response characteristic detecting means reaches a predetermined value and the moving distance of the carriage required for printing one line is shorter than the predetermined running distance, the moving distance of the carriage is set to A carriage control device for correcting a value equal to or greater than a predetermined traveling distance.