JPH03161356A - Printer - Google Patents

Abstract

PURPOSE:To judge more exactly when printing method is changed by a constitution wherein a count value is operated by reading a correcting count value in accordance with a printing data sequentially from a correcting count value memory means to add it to operate the count value. CONSTITUTION:Upon determining the printing method of a printing line before starting the printing, a CPU 1 reads out a correcting count value in accordance with a printing pattern data sequentially to add it and operates a dot duty value from the count value obtained from the adding to determine the printing method in accordance with the dot duty value. In this case, the number of printing dot and the correcting count value in accordance with the combination of the number of printing dot are stored in ROM 3 previously whereby the count value in accordance with a driving current can be operated more correctly. Accordingly, faulty printing, such as the dropping of a dot or the like, is neither generated nor a printing head 8 is overheated in the printing operation whereby positive printing can be effected.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention performs printing by selectively driving the printing elements while moving a print head having a plurality of printing elements in the printing direction. Regarding printers.

(Prior art) In general, in this type of printer, it is rare to drive all the printing elements arranged in the print head at the same time to print (referred to as "full dot printing"). A drive power source with a capacity sufficient to supply the power consumption for printing is not provided.

Rather, since the power consumption is usually about half that of the above case, costs are reduced by reducing the capacity of the drive power supply.

However, when printing figures, etc. using the drive power supply described above, the dot duty, which corresponds to the drive rate of the printing element, is higher than in normal character printing, so power consumption is large. ? Therefore, there were cases where the above-mentioned drive power source could not be used to drive the device reliably. As a result, there has been a problem that the print quality is further deteriorated, such as so-called missing dots. In addition, as the dot duty increases, the cumulative amount of drive current for the printing element temporarily increases.
As a result, the amount of heat generated by the print head increases, causing the problem of overheating.

Therefore, in order to solve these problems, there has conventionally been a method as disclosed in, for example, Japanese Patent Laid-Open No. 61-76373. That is, in the line to be printed,
The predetermined duty detection area is sequentially moved, the total count of print dots existing in that area is calculated, and the dot duty is calculated sequentially from this total count and the total number of printable dots in that area. Then, when the value of the dot duty is equal to or greater than a predetermined value, printing of that printing line is divided into parts. In other words, if the number of printed dots exceeds a certain number within the duty detection area, the number of printed dots is reduced by dividing the printing of that printing line, thereby eliminating the above-mentioned problem. This is to avoid it from happening.

(Problem to be Solved by the Invention) By the way, the reason why the number of printed dots is counted in this way is that the count value corresponds to the integrated value of the drive current flowing through the printing element. This is because the integrated value of the drive current is an important factor that determines the power consumption and heat generation amount of the print head.

However, in the following cases, the number of printed dots may not correspond to the integrated value of the drive current as described above. Moreover, the actual cumulative drive current value may be larger than the counted number of printed dots, and in this case, even though the dot duty value is determined to be smaller than the predetermined value, First, as described above, problems such as printing defects such as missing dots and overheating of the print head occur during the printing operation.

Such an example may occur, for example, in an impact type dot matrix printer. In other words, in this type of printer, dot wires are arranged as printing elements of the print head, and these dot wires are driven by magnetic attraction force by energizing a coil, thereby performing printing operations. ing.

However, in this case, the magnitude of the drive current when driving one dot wire alone and the magnitude of the drive current when driving adjacent dot wires simultaneously do not have a simple proportional relationship. This is because the dot wire forms part of the magnetic circuit for the coil.
This is because when the dot wires are driven, if their magnetic resistance increases as a result of being separated from the magnetic circuit, the driving current increases when adjacent dot wires are simultaneously driven. As a result, when driving adjacent dot wires at the same time, for example, more than twice as much driving current flows as a whole compared to when driving a single dot wire. This tendency becomes greater as the number of dot wires that are driven simultaneously increases and as the number of dot wires approaches.

The present invention has been made in view of the above circumstances, and its purpose is to be able to reliably determine whether or not to change the printing method, and to prevent the occurrence of printing defects and overheating of the print head. We aim to provide a printer that prevents printing as much as possible.

[Structure of the Invention] (Means for Solving the Problem) The present invention moves a print head having a plurality of printing elements along a printing line, and during the movement, prints the plurality of printing elements at a plurality of printing positions on the printing line. selectively driving the printing elements of
letter. Targeted at printers that print figures, etc., is a correction count value storage means for storing correction count values corresponding to the number of printing elements driven simultaneously and their combination patterns, and printing elements driven simultaneously at each printing position. a detection means for detecting the number of and a combination pattern thereof, a counter means for reading out and sequentially adding a correction count value corresponding to the detection result of the detection means from the correction count value storage means, and a count value of the counter means; The present invention is characterized in that it is constructed by providing a printing control means for changing the printing method by the print head based on the printing method.

(Function) According to the printer of the present invention, the detection means detects the number of printing elements driven simultaneously at each printing position and the combination pattern thereof, and the counter means performs a corresponding correction count based on the detection result. The values are read from the correction count value storage means and added sequentially. The print control means controls whether to change the printing method by the print head based on the count value of the counter means. In this case, the correction count value stored in the correction count value storage means varies depending on not only the number of printing elements but also their combination pattern. The corresponding value is set as the value to be converted. Therefore, for example, even if the number of printing elements is the same, if the drive current varies depending on the combination pattern,
A corresponding correction count value is set for each. As a result, it is possible to calculate a count value that more closely corresponds to the actual drive current, and it is possible to reliably determine whether or not to change the printing method.

(Example) Hereinafter, an example in which the present invention is applied to a dot impact type printer will be described with reference to the drawings.

First, in FIG. 1 showing the overall block configuration, a CPU for controlling printing operations and other operations is connected via a data bus 2 to a ROM 3, a RAM 4, a character generator (hereinafter referred to as CG) 5, and a human output. Circuit (hereinafter referred to as I
/O circuit) 6 and interface circuit (hereinafter referred to as 1)
/F circuit) 7. The CPUI has functions as a detection means, a counter means, and a print control means. The ROM 3 stores in advance a program for the CPU to carry out printing control, and also stores data indicating the total number of dots in a predetermined printing area. Further, the ROM 3 also has a function as a correction count value storage means, which will be described later. CG5 stores printing pattern data such as characters and figures corresponding to the printing code data. The RAM 4 includes an input buffer area for storing print code data provided from an external device such as a host computer (not shown) via the I/F circuit 7, and a CG5 based on this print code data.
A print buffer area and the like are provided for storing print pattern data read out from the printer. The print head 8 is
A plurality of dot wires (not shown) are arranged in a straight line as printing elements, and each of these dot wires is driven by a magnetic attraction force generated by energizing a coil (not shown). The print head 8 is connected to the I/O circuit 6 via a drive circuit 9, and drives the dot wires in response to print signals from the CPUI. The print head 8 is arranged on a carriage (not shown), and the carriage is driven by a carriage drive motor 1.
0 in the row direction. The carry/shift drive motor 10 is controlled by a drive signal from the CPUI via a drive circuit 11. A paper feed drive motor 12 for line-feeding printing paper is connected to the CP via a drive circuit 13.
Controlled based on drive signals from the UI.

Next, the drive current for the dot wires forming the print head 8 will be described. In this embodiment, in order to simplify the explanation, the number of dot wires in the print head 8 is assumed to be four. Generally, in impact type printers,
The current applied to the coil when driving a dot wire is not proportional to the current when driving a single dot wire or when driving multiple dot wires in close proximity, and the current flowing through the coil is lower than when driving a single dot wire. There will be more. According to the inventor's actual measurement data, the situation is as shown in FIG. 13, for example. That is, FIG. 3 shows the total drive current that flows when the number of sequentially driven dot wires among the four dot wires is increased. This shows that the value of the drive current is not simply proportional to the number of dot wires driven. In this case, for example, if you add an extra 0.5 to the number of dot wires that are driven adjacent to each other and count it, it will be approximately equal to the drive current.Hereinafter, the number of printed dots will be calculated based on this rule. The values shown in FIG. 2 are set as the corrected count values obtained according to the pattern. That is, FIG. 2 shows the corrected count values determined according to the above-mentioned rules for all combinations of four dot wires.

Next, the operation of this embodiment will be explained.

When the CPU starts operating according to the program stored in the ROM 3, it first stores the print code data given from the external device (host computer) via the I/F circuit 7 in the input buffer of the RAM 4, and then Based on the print code data, it is converted into print pattern data of CG5 and stored in the print buffer of RAM4 again.

Next, the CPU reads out the print pattern data for the first line (print line) to be printed from the print buffer in RAM4, detects the number of print dots and their combination pattern, and prints the data from the beginning to the predetermined print area. Within the range, the corresponding correction count values are sequentially read out from the ROMB, and the correction count values are sequentially added.

In this case, as described above, the correction count value is a value converted as shown in FIG. 2 according to the number of dot wires that are simultaneously driven during the printing operation of the print head 8 and the combination pattern thereof.

Then, the dot duty is calculated based on the total number of dots in the predetermined print area read from the ROM 3 and this total count value, and it is determined whether this dot duty value is equal to or greater than the predetermined value. . At this time, when the dot duty value is smaller than a predetermined value, the above-mentioned predetermined printing area is set by shifting backward in the printing line,
The dot duty is calculated again in the same manner as described above, and it is determined whether the dot duty value is greater than or equal to a predetermined value. Note that this predetermined value means that if normal printing operation is continued when the dot duty value is higher than this value, the print head 8 may become overheated or the printing operation may exceed the power supply capacity. This value indicates that a printing defect such as missing dots will occur, and such a predetermined value is determined in advance from the characteristics of the apparatus.

Thereafter, this process is repeated until the end of the print line, and when all the judgment results regarding the dot duty value are "NO", the normal printing operation, that is, printing is performed directly on the print head 8 according to the print pattern data. make the action take place.

On the other hand, when it is determined that the dot duty value is equal to or greater than the predetermined value, the printing method by the print head 8 is changed to, for example, divided printing without calculating the dot duty thereafter. That is, after this, printing of that print line is divided into two parts. In this case, the dividing printing method is, for example, by driving the odd-numbered dot wire of the print head 8 in the first printing operation,
This method involves driving the even-numbered dot wires in the second printing operation, thereby effectively reducing the dot duty. Therefore, during the printing operation, printing can be performed reliably without causing printing defects such as missing dots or overheating of the print head 8.

In this way, before starting printing, the CPU reads out the correction count values corresponding to the print pattern data and sequentially adds them to determine the printing method for the print line, and calculates the dot duty value from the count value obtained thereby. is calculated and determined according to this dot duty value.

In this case, since the number of print dots and the correction count value corresponding to the combination thereof are stored in the ROMB in advance, the count value corresponding to the drive current can be calculated more accurately. Therefore, in the printing operation, reliable printing can be performed without causing printing defects such as missing dots or causing the print head 8 to become overheated.

Further, the present invention is not limited to the above embodiments, but can be applied to, for example, the following cases. That is, in the printing device disclosed in Japanese Unexamined Patent Publication No. 61-112649, the corrected count value of the present invention is used instead of the count value, and while the corrected count value is sequentially added, a constant value is calculated at predetermined intervals by a subtracting means. may be subtracted, and a change in the printing method may be determined based on the result of adding the corrected count value.

In the above embodiment, for convenience of explanation, the print head 8 has four dot wires, but the same applies to a printer having a print head with more than four print elements. Of course, the rules for determining the correct count value are not limited to these, and a corrected count value suitable for the printer may be set as appropriate.

Further, in the above embodiment, a case has been described in which the predetermined printing area is set to a range shorter than the length of the printing line, but the predetermined printing area is not limited to this, and may be set to the same length as the printing line.

Furthermore, in the above example, the printing method is divided into parts, but the printing method is not limited to this. There are various methods such as

[Effects of the Invention] As explained above, according to the printer of the present invention, the correction count value determined based on the number of printing elements driven simultaneously and the combination thereof is stored in advance in the correction count value storage means, Since the counter value is calculated by sequentially reading and adding the correction count value according to the print data from the correction count value storage means by the counter means, even if the number of driven printing elements is the same, the combination Accurate count values can be calculated under different conditions. Therefore, an excellent effect is achieved in that a judgment when changing the printing method can be made more accurately.

4 Illustrative Explanation of the Drawings The drawings show one embodiment of the present invention, FIG. 1 is a block diagram of the overall configuration, FIG. 2 is a diagram showing the sleeve count value corresponding to the print pattern data, and FIG. It is a figure which shows the actual measurement data which shows the drive current of a wire dot.

In the drawing, 1 is a CPU (detection means, counter means, and print control means), and 3 is a ROM (corrected count value storage means).
, 4 is a RAM, and 8 is a print head.

Claims (1)

[Claims] 1. Moving a print head having a plurality of printing elements along a printing line, and selectively driving the plurality of printing elements at a plurality of printing positions on the printing line during the movement; letter,
In a printer that prints figures, etc., there is provided a correction count value storage means for storing a correction count value corresponding to the number of printing elements driven simultaneously and a combination pattern thereof, and the number of printing elements driven simultaneously at each printing position. and a combination pattern thereof; a counter means for reading out and sequentially adding a corrected count value corresponding to the detection result of the detecting means from the corrected count value storage means; and based on the count value of the counter means. A printer comprising a print control means for changing a printing method by the print head.