JPH07205515A - Carriage drive device for serial printer - Google Patents

Abstract

PURPOSE:To improve the printing throughput by controlling a carriage in the low speed mode when the measuring printing digit number is less than the given value and controlling the same in the high speed mode when the number is over the given value. CONSTITUTION:Printing data to be supplied is transmitted to a printing digit number check circuit 2 by a CPU(central processor unit) 1 and the number of printing digits is measured. Then the measured number of printing digits is compared with the preset given value. When the sensed printing digit number is smaller than the given value, the low speed mode is selected; when the same is larger than the given value, the high speed mode is selected. A selection signal is output to a carriage motor drive circuit 5, and control is performed by driving a carriage motor 6 in compliance with the respective modes. Simultaneously the printing data is output to a printing head drive circuit 3 to drive and control a printing head 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carriage driving device for a serial printer.

[0002]

2. Description of the Related Art Recent printers are required to have higher speeds, and serial printers are no exception. As one of the means for increasing the speed of a serial printer, the printing throughput is improved by increasing the driving speed of a carriage on which a print head is mounted.

[0003]

However, if the drive speed of the carriage is increased, the throughput may be reduced, which is not always the case. That is, since printing by the print head is performed in an area in which the carriage moves at a constant speed, a run-up time for rising and falling that is proportional to the driving speed of the carriage is required. Therefore, the time for the approach run becomes longer as the drive speed of the carriage is increased.
Therefore, when the drive speed of the carriage is increased, the proportion of the run-up time increases when the number of print digits is small. As a result, when the number of print digits is small, the print efficiency is reduced and the throughput is reduced.

Therefore, an object of the present invention is to improve the print throughput by switching the drive speed mode of the carriage according to the number of print digits in each print line.

[0005]

In order to achieve the above object, a carriage driving device for a serial printer of the present invention drives a carriage having a print head mounted thereon and the carriage in a direction orthogonal to a paper feeding direction. A carriage driving means, a central processing unit for controlling the carriage driving means, and a print digit number check circuit for comparing the print digit number of print data supplied to the central processing unit from an external device with a preset specified value. It has and. The central processing unit has a carriage driving means so that the carriage moves in the low speed mode when the number of print digits is less than the specified value and moves in the high speed mode when the number of print digits is more than the specified value. Is configured to control.

[0006]

The print digit number of the print data supplied from the external device to the central processing unit is measured by the print digit number check circuit, and the measured print digit number is compared with the specified value. The comparison result is sent to the central processing unit, and when the number of print digits is less than the specified value, the central processing unit controls the carriage driving means so that the carriage moves in the low speed mode, and the number of print digits is specified. When the value is equal to or more than the value, the carriage driving means is controlled so that the carriage moves in the high speed mode. The stipulated value is set to the number of print digits in which the throughputs in the low speed mode with a small run-up area and the high speed mode with a large run-up area are compared and the two match. Therefore, the execution value of the print throughput is improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Generally, in a serial printer, in addition to the print area, the rising distance of the carriage that moves until the carriage reaches a constant speed and the fall distance of the carriage that moves before the carriage stops after the printing operation, that is, I need a run-up distance.

As shown in FIGS. 2 and 3, letting a be the rising distance and the falling distance when the carriage is driven in the low speed mode, and b when it is the carriage driven in the high speed mode. The distance is
2a is required in low speed mode, 2b in high speed mode
Is required. Here, assuming that the number of print digits is y, in the low speed mode, the displacement X of the carriage required for the printing operation for one line is X.
₁ is at least X ₁ = y + 2a, and the carriage displacement amount X ₂ in the high speed mode is at least X ₂ = y
It becomes + 2b.

Since the approach distance is proportional to the driving speed of the carriage, 2a <2b. As a result, as is clear from the figure, the ratio of the run-up distance to the number of print digits is larger in the high-speed mode when compared with the same number of print digits. This ratio becomes more remarkable as the number of print digits y becomes smaller. Therefore, when the number of print digits is large, it is possible to overcome the handicap of the time required for the run-up due to the displacement of the carriage at a high speed and increase the throughput. However, when the number of print digits y is small, the throughput is reduced because the ratio of the time required to move the approach distance 2b to the processing time in which the carriage is displaced at a high speed and shortened increases. Thus, when the number of print digits decreases and reaches a certain number, the throughput in the high speed mode becomes the same as that in the low speed mode, and when the number of print digits further decreases thereafter, the throughput becomes higher in the low speed mode.

Thus, in view of the fact that the low speed mode is advantageous when the number of print digits is small and the high speed mode is advantageous when the number of print digits is large, the present invention has a small print digit number. The drive speed mode of the carriage can be switched so that the low speed mode is used at times and the high speed mode is used when the number of print digits is large.

FIG. 1 shows a system of a carriage driving device capable of switching the above speed modes. The system of this apparatus is a central processing unit (CP) to which print data is supplied from an externally connected device (not shown) such as an electronic computer.
U) 1 and a print digit number check circuit 2 for checking the print digit number of this and print data. The print digit number check circuit 2 compares the print digit number of the print data supplied to the CPU 1 with a specified value preset in a storage circuit (ROM) (not shown) and outputs the result to the CPU. .

A print head drive circuit 3 for controlling the drive of the print head 4 is connected to the CPU 1, and the print head can be driven based on the print data supplied to the CPU. A carriage motor 6 as a carriage driving means is connected to the CPU 1 via a carriage motor driving circuit 5. The carriage motor drive circuit 5
The carriage motor 6 is driven by switching to the high speed mode or the low speed mode by the output from the print digit number check circuit 2.

The carriage 7 is reciprocally movable by a carriage motor 6 in a direction orthogonal to the paper feeding direction. The print head 4 is driven by the CPU 1 with the print pin in a drive cycle related to the moving speed of the carriage 7.

As shown in FIG. 4, when the print data is supplied to the CPU 1, the print digit number check circuit 2 measures the print digit number of the print data, and the print digit number and the preset specified value are set. To determine whether the number of print digits is larger or smaller than the specified value. CPU1
If the number of print digits is equal to or greater than the specified value (YE
The high speed mode is selected in S), and the low speed mode is selected when the number of print digits is smaller than the specified value (NO). One of these selected signals is output to the carriage motor drive circuit 5, the carriage motor 6 is driven by this signal to displace the carriage 7, and printing is performed by the print head 4. In parallel with this operation, print data is output from the CPU 1 to the print head drive circuit 3, and the print head 4 is drive-controlled to perform desired printing.

Here, how to set the specified value will be described. FIG. 5 shows the relationship between the number of print digits and the number of print processes (throughput) per unit time when the high speed mode and the low speed mode are set.

Here, as an example, the steady speed when the carriage displaces the print area in the low speed mode is 4
20 CPS, 520 CP for high speed mode
S. In any case, the throughput decreases as the number of print digits increases. In the range where the number of print digits is large, the throughput in the high speed mode is higher than that in the low speed mode, but in the range where the number of print digits is small, the ratio of the start-up time and the fall time is large (Figs. 2 and 3). See), the throughput is smaller in the high speed mode than in the low speed mode. Therefore, the change curve m in the low speed mode and the change curve n in the high speed mode are
It intersects at some point on the graph. In this embodiment, the print digits intersect at 50 digits. Therefore, if the print digit number of 50 digits or more is set to the high speed mode, and if the print digit number of less than 50 digits is set to the low speed mode, printing can always be performed in the high speed mode of high throughput.

Therefore, the prescribed value is set to 50, and when the number of print digits is less than 50, the low speed mode is selected, and when it is 50 or more, the high speed mode is selected. As a result, the carriage can be displaced in the speed mode in which the throughput is always high, so that the printing throughput can be increased regardless of the increase or decrease in the number of print digits.

Of course, since this specified value is an example,
It must be set according to the various conditions of the printing device.

[0019]

According to the present invention, the carriage drive speed mode is selected for each print line to the speed mode with the higher throughput, so that the throughput is always high regardless of the number of print digits. Can be printed.

Further, since the printing operation in the low speed mode is performed during the printing operation of a plurality of lines, the heat generation of the carriage motor can be reduced and the durability of the print head can be improved. Further, since the time for cooling can be reduced, there is an effect that continuous printing for a long time becomes possible.

[Brief description of drawings]

FIG. 1 is a system block diagram showing the configuration of the present invention.

FIG. 2 is a relationship diagram between the displacement of the carriage and the driving speed of the carriage when the number of print digits is large.

FIG. 3 is a relationship diagram between the displacement of the carriage and the driving speed of the carriage when the number of print digits is small.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a relationship diagram between the number of print digits and throughput.

[Explanation of symbols]

 1 Central Processing Unit (CPU) 2 Print Digit Number Check Circuit 4 Print Head 6 Carriage Driving Means 7 Carriage

Claims (1)

[Claims] 1. A carriage on which a print head is mounted, a carriage driving means for driving the carriage in a direction orthogonal to a paper feed direction, a central processing unit for controlling the carriage driving means, and a central processing unit for controlling an external device. A print digit number check circuit that compares the print digit number of the print data supplied to the device with a preset standard value is provided. For a serial printer, wherein the carriage moves in a low speed mode, and the carriage driving means is controlled so that the carriage moves in a high speed mode when the number of print digits is equal to or more than the specified value. Carriage drive.