JPS6125857A - Overload detecting printing method in dot printer - Google Patents

Abstract

PURPOSE:To eliminate the irregularity of a printed character, by allowing energy supplied to the coil of a printing head to fail immediately before the beginning of split printint and printing a thinly printed part in a duplicate manner when split printing is performed. CONSTITUTION:A processor conrols a printing head control circuit corresponding to the lowering in the power source voltage of a power source part and the width of the pulse fed out to a printing head is successively windened to make the energy applied to a coil same. A sensor stores the address of the printing completed part of a line buffer region and printing operation is interrupted while a space motor is controled through a space control circuit and a carriage is stopped before returned to the original direction. For example, the processor again drives the space motor to operate a printing start address from the address of the line buffer region end character patterns are successively printed like 10, 6, 7 for example, 1/3 printing is performed. Then, a printing head is returned to 13 and 10', 6', 7' are subjected to 1/3 printing in the same way as mentioned above. Again, the printing head is returned to 1/3 and 10'', 6'', 7'' are subjected to 1/3 printing to complete the printing of a pertinent line.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dot printer that uses a plurality of printing elements to form characters with dots, and in particular, when driving a plurality of printing elements at the same time, there is a method for driving the printing elements. The present invention relates to an overload detection printing method that prevents deterioration in printing quality when transitioning to split printing due to insufficient energy.

For example, in a wire dot printer that prints characters by forming dots using a plurality of printing elements, the print head is provided with the same number of coils as the number of bins to drive a plurality of bins. An excitation pulse is applied to the coil according to the pattern to be printed, and an excitation current is applied to drive the bottle to print.

The coil to which this excitation current is supplied is operated by being energized for a time equal to the pulse width by a driver that is turned on by an excitation pulse. A direct current obtained by rectifying a commercial power source is usually used as a power source for supplying energy to operate the coil.

Few power supplies that supply this direct current are equipped with a constant voltage device due to cost considerations, and generally supply a rectified commercial power source.

Therefore, voltage fluctuations in the commercial power supply directly appear as voltage fluctuations in the DC power supply.

The energy supplied to the coil is determined by voltage and current. Therefore, when the power supply voltage decreases, countermeasures are taken to prevent the printing performance from decreasing by increasing the duration of the current supplied to the coil. In other words, a circuit is provided to detect voltage fluctuations in the power supply, and when the voltage is high, short pulses are supplied to the driver that supplies excitation current to the coil, and as the voltage decreases, pulses with longer widths are supplied. controlled to do so.

However, if the voltage drops below a certain limit, the current supply time becomes too long, and the total power supplied to the coil becomes large, causing an overload of the power supply and causing the coil to generate abnormal heat, causing the print head to fail. Since the temperature rise increases, dividing the amount of energy required at one time is dealt with by performing split printing.

That is, when printing a character, the number of coils that are simultaneously driven at the same timing is divided, and the character is printed in a plurality of times. By doing so, it is possible to reduce the voltage drop of the power supply and also to prevent a decrease in printing ability. However, it is necessary that there be no unevenness in the print density of characters near this division printing start point.

[Prior Art] In conventional wire dot printers, based on the operation of a circuit that detects a voltage drop in the power supply supplied to the coil of the print head, when the voltage drops below a certain limit, printing is interrupted once. , thereafter, divisional printing is started from that point.

FIG. 2 shows an example of a voltage fluctuation detection circuit.

The DC voltage obtained by rectifying the commercial power supply is Vd, and the standard voltage is V.
Let it be s. Standard voltage Vs is divided by resistor R1 and resistor R2 and applied to operational amplifiers 1 to 5, respectively. DC voltage V
d is divided by resistors R3 to R8 and connected to operational amplifier 1, respectively.
~5 is applied.

When the DC voltage Vd is high and the terminal voltage of resistor R8 is greater than the terminal voltage of resistor R2, all operational amplifiers 1 to 5 output their respective outputs VLO, VLI, Vll, VL3 . “1” in VL4
” is sent.

As the DC voltage Vd decreases, the operational amplifier 5 outputs V
L4 is set to "0", and then operational amplifier 4 sets output VL3 to "0".
When the operational amplifier 4 sets the output VL2 to "0", the operational amplifier 3 sets the output VL1 to "0", the operational amplifier 2 sets the output VLI to "0", and the operational amplifier 1 sets the output VLO to "0", That is, when operational amplifiers 1 to 5 all send out "0", division printing is started.

FIG. 3 is a diagram illustrating the divided printing operation.

When printing characters, image data, etc., the voltage is monitored for each vertical dot row, that is, each column, and if the voltage drops below a specified value even while printing characters, a division printing operation immediately starts from that column.

That is, if the characters are printed as ■ and ■ and the operational amplifiers 1 to 5 in FIG. 2 all send out "0" at the time point ■ in the middle of printing the character ■, then, for example, a three-division printing operation starts.

At this time, the print head moves as shown by the arrow, interrupts the printing operation when it moves from ■ to ■, stops once, returns to the original position, starts again from position ■, and when it reaches constant speed, ■
■, ■, print 1/3 to the end of the line, return to the position of ■, and ■゛.

■°, ■゛ and l/3 are printed, return to the position of ■, and ■
゛°, ■1. ■Print °° and 1/3 to complete printing of that line.

[Problem that the invention seeks to solve]

As mentioned above, when the power supply voltage drops below a predetermined value, printing is performed by dividing the subsequent parts (after ■ in Figure 3), but the problem at this time is immediately before the power supply voltage drops below the predetermined value. These are the print densities in multiple columns (regions marked ■ in FIG. 3). That is, there is an error in the set value of the predetermined value,
It is difficult to eliminate this error. Therefore, when looking at a certain power supply, before the voltage drops below the set value, the voltage has already dropped to a level where sufficient printing ability cannot be achieved, and there is a possibility that sufficient impact force cannot be obtained and the printing density will decrease.

On the other hand, if the set value is set sufficiently large, split printing will occur frequently, which will unnecessarily reduce printing processing efficiency. Therefore, in the past, the set value was set to a small value in consideration of fluctuations in the power supply voltage, and as a result, as described above, there was a drawback that a plurality of columns immediately before the start of division were printed thinly.

[Means for solving problems]

The above problem occurs when a dot printer prints subsequent characters by dividing them by detecting that the power supply voltage has dropped below a predetermined value. I made it to print,
This problem is solved by the overload detection printing method in a dot printer according to the present invention.

[Effect]

In other words, when there is insufficient energy supplied to the coil of the print head just before the start of divided printing, areas that are printed thinly are printed over and over again during divided printing to eliminate unevenness in the printed characters. .

(Embodiment) FIG. 1 (81 is a block diagram of a circuit showing an embodiment of the present invention, and fbl is a diagram explaining the operation of ta+.

The processor 6 reads a program stored in the ROM 7 and operates. Print data is also sent from the host device via the interface control circuit 9.

The processor 6 temporarily stores this print data in the RAM 8 and then reads it out. If the print data is a character code, the processor 6 reads the corresponding character pattern from the character generation circuit 12 and writes it into the line buffer area in the RAMB again. The character pattern in the line buffer area is then sent to the print head control circuit 15 and printed by the print head 16.

At this time, the processor 6 simultaneously controls the space control circuit 13 and drives the space motor 14 to cause the carriage carrying the print head I6 to perform a space motion.

Further, if the processor 6 includes a line feed command in the print data read from the RAM 8, it controls the line feed control circuit IO to drive the line feed motor 11 to feed the paper.

From the voltage fluctuation detection circuit shown in FIG. 2 provided in the power supply section 18, the output of the operational amplifier sequentially changes from 1" to "0" as described above via the input port 17 in response to a drop in the power supply voltage. This is reported to the processor 6. The processor 6 controls the print head control circuit 15 in response to the change, and sequentially widens the width of the pulse sent to the print head 16 so that the energy given to the coils is the same. Do it like this.

However, when the outputs of all the operational amplifiers become "0", the process shifts to divided printing at this point, so the processor 6 stores the address of the print-completed portion of the line buffer area and temporarily switches the print head control circuit 15 on. control and interrupt the printing operation. Then, the space motor 14 is controlled via the space control fi11 circuit 13 to stop the carriage and then return it to its original direction.

For example, in Figure 1), the carriage uses the space motor 14 to move the print head 16 from the position of Assume that the process shifts to split printing during printing. That is, when the division printing is started from ◯ in FIG. 3, the processor 6 temporarily stops the print head 16 at the [phase] position and returns it to the original direction.

In this case, the processor 6 controls the space motor 14 so that the division printing start position of the print head 16 is returned a plurality of dots beyond the division start detection point. That is, the carriage stop position 0 is specified so as to cover the printing area shown in FIG.

Here, the processor 6 drives the space motor 14 again, and when the print head 16 reaches a constant speed, calculates a print start address from the address in the line buffer area, and sequentially prints the character pattern as [phase], ■, ■, for example. Print 1/3. Then return the print head 16 to 0 again and do the same as above [phase]
゛, ■°, ■° and 1/3 print, and print head 16 until 0
, and print 1/3 of [phase]゛, ■°゛, ■゛°,
Finish printing the corresponding line.

Therefore, since the printing area of ``■'' is printed overlappingly, the thinly printed portion disappears.

In addition, when performing divided printing, the number of divisions is not limited to 3 divisions, but may be 2 divisions or 4 divisions, and the division method is not limited to top, middle, and bottom.
If there are 24 vertical dots, the first pass will be 1.4, 7. −． 2
2nd dot, 2.5, 8. in the 2nd pass. −． 23rd dot, 3rd bus 3°6.9. −． The 24th dot may be printed separately.

Furthermore, when performing divided printing, printing is not limited to printing when all the print heads move in the same direction, but printing may be performed on the way back.

〔Effect of the invention〕

As described above, when performing divided printing, the present invention can prevent uneven printing due to delay in the circuit that detects the starting point of divided printing.

[Brief explanation of drawings]

Figure 1 (al is a block diagram of a circuit showing an embodiment of the present invention, (bl is a diagram explaining the operation of ta+, Figure 2 is a diagram showing an example of a voltage fluctuation detection circuit, Figure 3 is a divided printing It is a diagram explaining the operation. In the figure, 1 to 5 are operational amplifiers, 6 is a processor, 7 is a ROM,
8 is a RAM, 9 is an ink face control circuit, 10 is a line feed control circuit, 11 is a line feed motor, 12 is a character generation circuit, 13 is a space control circuit, 14 is a space motor, 15 is a print head control circuit, 16 is a print head , 17 is an input port, and 18 is a power supply section. Nanakura Tsu Iza7 13jy L lro I

Claims (1)

[Claims] By detecting that the power supply voltage has fallen below a predetermined value, dot printers that print subsequent characters in segments can print the columns that were printed immediately before starting split printing. Features: Overload detection printing method for dot printers.