JPH0566266B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] A serial printer that forms print by dots, which includes a dot counting means for print data, a time counting means from the end of the previous printing energization to the start of the current printing energization, and a counting device. By providing a judgment means to judge the limit value of the number of dots that can be printed this time based on the number of dots and the time count value, the printing load is controlled and the maximum rating of the printing head and head drive power supply circuit etc. is lowered, thereby reducing costs. Improvements can be made.

[Industrial application field]

The present invention relates to a serial printer such as a wire dot printer, and more particularly to a printer that can improve the cost of a print head, head drive power supply circuit, etc. by controlling the printing load.

Recently, with the advancement of office automation, various computer terminals, word processors,
Wire dot printers and thermal printers have been developed and put into practical use as print output devices for facsimile machines and the like.

These printers form prints in the form of dots by selectively energizing multiple printing elements, and the ratings of the print head, head drive power supply circuit, etc. are set based on the maximum energization value. A method that can optimize quality or protect against burnout is desired.

[Conventional technology]

A conventional example will be explained with reference to FIGS. 6 to 8.
The same reference numerals indicate the same objects throughout the figures.

As shown in FIG. 6, a print head 1 and a ribbon cassette 4 are mounted on the carrier 5, and the print head 1 carries the print ribbon 4 supplied from the ribbon cassette 4 onto the print paper 3 set on the platen 2.
They face each other via a.

The carrier 5 is slidably fitted into a guide shaft 6 which is arranged parallel to the platen 2, and a feed screw 7 which is also parallel to the platen 2 is screwed into the carrier 5.
The feed screw 7 is connected to the space motor via the belt 8.
The print head ₁ can be moved back and forth in the directions of arrows A and B in the figure by forward and reverse rotation of the space motor _M1 . Further, the printing paper 3 is transported in the direction of arrow C by the transport mechanism 9.

The print head 1 is equipped with a plurality of print magnets for forming prints by dots.

As shown in FIG. 7, the printing magnet 10 is
An electromagnet 11 consisting of a core 11a and a coil 11b,
It is comprised of an armature 13 having a wire 12 at its tip, a drive spring 14 that elastically supports and drives the armature 13, yokes 15a, 15b, and a permanent magnet 16 that normally attracts the armature 13 to the core 11a.

Therefore, a print pulse is sent to the print head 1,
A permanent magnet 1 is attached to the coil 11b of the printing magnet 10.
When the electromagnet 11 is excited by applying a current that cancels out the magnetic flux of the electromagnet 11, the armature 13 that has been attracted to the electromagnet 11 is released and repulses in the direction of the arrow E due to the restoring force of the drive spring 14. As the wire 12 protrudes in the same direction, the leading end collides with the printing paper 3 via the printing ribbon 4a, dot printing is performed, and the excitation is immediately released and restored.

In addition, in FIG. 8, the interface control section 1
7 receives the print information signal a sent from a host device such as a computer (not shown), and prints the print data b.
and control data, sends a space signal c to the space control section 17, a line feed signal d to the line feed control section 19, and sends the print data b to the buffer 2.
The print control unit 21 has the function of causing the head drive circuit 22 to operate the print magnet of the print head 1 based on the print pulse sent from the buffer 20.

Further, 23 and 24 indicate motor drive circuits, and _M2 indicates a line feed motor.

With such a configuration and function, when the space signal c to start printing is sent from the interface control unit 17, the space control unit 18 is activated.
The print data b sent from the buffer 20 is sent to the print control section 21, and a print pulse operates the print head 1. Printing is thus performed, and the space control section 18 causes the motor drive circuit 23 to rotate the space motor _M1 , and the print head 1 prints on the print paper 3 while moving in the direction of arrow A together with the carrier 5.

When printing for one line is completed, a line feed signal d is sent to the line feed control section 19, and the motor drive circuit 24 rotates the line feed motor _M2 to feed the printing paper 3 in the direction of arrow C for a line feed.

In this manner, dot printing is performed.

[Problem that the invention seeks to solve]

According to the above conventional method, there are cases where the printing head 1 uses a part of the plurality of printing wires 12 and cases where it uses many printing wires 12 at the same time. The printing magnets 10 are excited at the same time, and the amount of energization increases in proportion to the number of printing magnets, resulting in heavy duty and increased heat generation.

Furthermore, when printing a large number of dots in succession, the next dot is printed by the printing pulse before it is cooled down, and the temperature of the printing head 1 gradually rises due to the so-called heat accumulation effect, causing overheating. It will eventually burn out. Similarly, the power supply circuit of the print drive circuit 22 is continuously loaded.

To deal with this, the printer is designed with the maximum rating of the current capacity that can withstand continuous maximum loads, and therefore the difference between the maximum rating and the steady-state rating is significant, and the print head 1,
There is also the problem that the capacity of power supply circuits, etc. is of excessive quality, increasing costs.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention.

In the figure, 25 is a dot counting means for counting the number of dots in the print data, 26 is a time counting means for counting the time from the end of the previous printing energization to the start of the current printing energization, that is, the dot printing interval time, and 28 is the number of dots counted. This determination means determines the limit of the number of dots that can be printed this time based on the number of printed dots and the time count value.

Therefore, based on the determination result by the determination means 28,
The printing element is configured to control driving of the printing element.

[Effect]

The number of dots in the print data is counted by the dot counting means 25, and on the other hand, the time from the end of the previous printing energization to the start of the current printing energization is counted by the time counting means 26.

Based on the counted number of dots and the time count value, the determining means 28 determines the limit of the number of dots that can be printed this time, and based on this determination, the number of dots that can be printed this time is controlled. In other words, by dividing the printing into multiple times to reduce the load for one printing, etc., by controlling the drive of the printing element so that the load current does not exceed a certain value, the printing head and printing speed can be reduced. The electric capacity of the drive power supply circuit for the head can be set low, resulting in cost improvement.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 2 to 4. The same reference numerals indicate the same objects throughout the figures.

FIG. 2 is a block diagram of the main parts, and parts corresponding to those in FIG. 1 are shown surrounded by dashed lines.

In the figure, the counter 25a has print data b
This is a dot counting means for counting the number of dots _N2 .

The timer 26a is a time counting means that counts the time from the end of the previous printing energization to the start of the current printing energization.

The previous dot number memory 27 is a memory that stores the previous printed dot number _N1 .

The printable limit value table 28a is, for example,
This memory is composed of a ROM and stores the limit value of the number of printable dots corresponding to the combination of the number _N1 of previously printed dots and the time count value T.

The comparison/determination section 28b compares the number of printable dots n and the number of dots _N2 , and sends the determination result to the print control section 2.
It has a function to send to 1a.

Since it has such a configuration and function, the operation will be explained with reference to the flowchart in FIG. 3 and the timing chart in FIG. 4. First, when the previous dot printing is completed, the timer 26a is activated and starts counting time. .

The current print data b sent from the interface control section 17 is stored in the buffer 20 and sent to the print control section 21a.

Then, the timer 26a stops counting time at the timing of point I in FIG. 4, and sends the time count value T to the printable limit value table 28a. Timer 26a is cleared.

Also, at the timing of the dots in Figure 4, the number of previously printed dots stored in the previous dot number memory 27
N ₁ is read and printable limit value table 28
Sent to a.

On the other hand, the number of printed dots of the printed data b is counted by the counter 25a, and at the timing of the dot in _FIG .
sent to.

Based on the previously printed dot number N ₁ and the time count value T, the printable limit value n is read out from the printable limit value table 28a and sent to the print control section 21a at the timing indicated by the dot in FIG.

The comparison/judgment section 28b compares the number of dots to be printed this time _N2 with the printable limit value n, and notifies the printing control section 21a of the judgment result at the timing indicated by the dot in FIG. 4. That is, if N ₂ ≦n, the print control section 21a directly sends out the print pulse and performs the print operation.

If N ₂ >n, printing is performed by dividing the print into upper and lower halves. That is, printing is divided into a plurality of times to lighten the load of one printing.

When printing is completed, the number _N2 of dots printed this time is sent from the counter 25a to the previous dot number memory 27 and updated and stored. That is, the number of dots printed this time will be _N1 for the next printing. Thus the counter 25a
count is cleared.

A different embodiment is shown in FIG. Second
The same reference numerals as in the figure indicate the same objects. Further, in FIG. 5, parts corresponding to those in FIG. 1 are surrounded by a dashed line. The difference between FIG. 5 and the embodiment shown in FIG. 2 is that
Printable limit value table 28 for printable limit value n
The method is to use a calculation means instead of searching from a.

That is, in the figure, the setting section 28c is a memory in which a predetermined value of the number of dots is set.

The calculation determination unit 28d calculates the number of dots printed last time N ₁ ,
This calculation determining means performs calculations based on the time count value T, the number of dots printed this time N ₂ , and a predetermined value N ₀ and determines the limit of the number of dots printed this time.

Therefore, from the previous printing dot number N ₁ and the time count value T, the printable limit value n is calculated from the heating level that includes the cooling progress from the previous printing to just before the current printing, and this is compared with the current printing dot number N ₂ . hand,
If N ₂ ≦n, print operation is commanded as is, and N ₂
If >n, the printing is divided into upper and lower parts and the printing operation is commanded.

By reducing the printing load in this way, it is possible to protect the printing head 1 from burnout, and the maximum rating of the printing head 1 and the head drive power supply circuit can be appropriately set to a low value, resulting in miniaturization and cost improvements. can be achieved.

In the above embodiment, the case of a wire dot printer has been described, but the present invention can also be applied to other printers that form prints using dots by energizing a printing element, such as a thermal printer, and similar effects can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent excessive quality of the print head, head drive power supply circuit, etc., and it is possible to obtain a compact and low-cost printer.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is a main block diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of the embodiment, Fig. 4 is a timing chart of the embodiment, and Fig. 5 6 is a perspective view showing an outline of a wire dot printer, FIG. 7 is an explanatory view of a printing magnet, and FIG. 8 is a block diagram showing a conventional example. In the figure, 1 is a print head, 10 is a print magnet, and 11 is a print head.
is an electromagnet, 12 is a print wire, 17 is an interface control unit, 18 is a space control unit, 19 is a line feed control unit, 20 is a buffer, 21 is a print control unit,
22 is a head drive circuit, 23 and 24 are motor drive circuits, 25 is a dot counting means, 25a is a counter, 26 is a time counting means, 26a is a timer, 2
7 is the previous printing dot memory, 28 is the determination means, 2
8a is a printable limit value table, 28b is a comparison/judgment section, 28c is a setting section, and 28d is a calculation/judgment section.

Claims (1)

[Scope of Claims] 1. An apparatus for selectively energizing a plurality of printing elements facing a printing medium to print dots on the printing medium, comprising: a dot counting means 25 for counting the number of dots in printing data; and a previous printing. It is equipped with a time counting means 26 for counting the time from the end of energization to the start of energization for current printing, and a determining means 28 for determining the limit of the number of dots that can be printed this time based on the counted number of printed dots and the time count value. . A printer characterized in that a printing element is driven and controlled based on the determination result by the determining means 28. 2. A patent characterized in that the determination means 28 is provided with a printable limit value storage means in which a limit value of the current printable dot number corresponding to the combination of the counted dot number and the time count value is stored. A printer according to claim 1. 3. The determining means 28 includes a setting section in which a predetermined value for the number of printable dots is set, and an operation for calculating a limit value for the number of dots that can be printed this time based on the predetermined value, the counted number of dots, and the time count value. 2. A printer according to claim 1, further comprising means.