JPH0242673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving method for an impact type dot line printer, and more particularly to a driving method for preventing printing defects caused by a drop in hammer driving voltage.

An impact-type dot line printer is a type of printer that forms printed characters as a collection of dots, and hammers placed at regular intervals on a line strike the paper surface while moving along the line. Characters are formed by printing, and when one line of characters is completed, the paper is fed one line pitch, and this time printing is repeated while moving in the opposite direction. The printing range of one line is divided for each hammer.

For example, a dot line printer that divides one line into 20 is equipped with 20 hammers in parallel. Typically, this type of printer uses a single power supply to drive the hammers, but printing the highest density dot pattern requires sufficient current to power all 20 hammers. If this printing continues, the power supply voltage of the power supply panel decreases. This is because the capacitor that the power board has in parallel with the output generally continues to discharge. Therefore, conventionally, in order to avoid printing defects due to this drop, a large-capacity power supply panel was required, taking this drop into account.

An object of the present invention is to provide a dot line printer that can print well without using such an expensive, large, and large-capacity power source.

For this reason, in the present invention, during the drive process of a commonly used dot line printer, a process is provided to monitor the output voltage of the power supply panel immediately before the hammer strikes, and if the output voltage is high compared to the set voltage, printing continues. , if it is low, the hammer drive and paper feeding are temporarily stopped and the hammer continues scanning while waiting for the power supply voltage to recover.
By driving in such a way that the operation resumes from the print position where it stopped, even when printing a single dot line, if the power supply voltage drops due to continuous printing with high dot density, the printing will be divided into multiple times, so the printing will be faster. No more defects.

Next, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the dot line printer has a hammer bank 2, which is a fixing means for fixing a plurality of printing hammers H ₁ to H _o , facing a stationary platen 1. The printing is performed by moving the printing hammer left and right and controlling whether or not to drive the printing hammer at each printing timing by a program. This printing control is based on U.S. Patent No.
Since this is a well-known technique as described in the specification of No. 3941051, only the portions related to the present invention will be described in detail here.

According to this control, one dot line is printed while the hammer bank 2 moves from left to right,
The paper is fed one dot line pitch, and the next one dot line is printed while moving from right to left. Repeat the above operations to proceed with printing.

FIG. 2 shows a hammer drive circuit and a power supply voltage monitoring circuit according to an embodiment of the present invention. In FIG. 2, the hammer drive circuit includes a plurality of hammer coils L ₁ to
These hammer coils L ₁ to _{L o}
power is connected to. Furthermore, the power supply is connected to a power supply voltage monitoring circuit. This power supply voltage monitoring circuit has a comparator 3 to monitor the power supply voltage, and the power supply voltage V is connected to the reference voltage V _R and the resistor R _{1 .}
and the set voltage determined by the division ratio of _R2 ( _R2・
When V _R /(R ₁ + R ₂ ) or less, comparator 3
output becomes high level.

Figure 3 shows the relationship between printing timing and printing operation.
Figure 4 shows the time chart at that time.

The processor that performs printing control in this embodiment always checks the voltage monitoring signal a immediately before the printing timing, and if this signal a is at a low level, it immediately prints that dot. When the signal a is at a high level, the processor temporarily stops printing (driving the hammer) and at the same time prohibits the paper feeding operation.

According to FIGS. 3 and 4, as printing continues at the maximum dot density, the power supply voltage e decreases. This power supply voltage e drops to the set voltage before striking the 8th dot of the print moving leftward, and the printing is stopped. Therefore, the print timing signal c is generated by the movement of the hammer bank 2, but the hammer excitation signal d is not outputted because the processor stops printing. This printing stop continues for the period required for one reciprocation of the hammer bank 2. During this time, the hammer bank 2 turns back twice, but since the paper feeding operation is prohibited, the hammer simply feeds on the same line on the paper surface. When timing 8 is reached during right feed, the processor cancels the print stop and paper feed prohibition, and returns to normal processing. Then, the timing of 8 is recognized and the voltage monitoring signal a is checked before printing. This time, the power supply voltage has been restored due to the waiting time for one round trip.
Since the signal a is at a low level, printing is executed. Printing is completed by repeating the same steps.

As explained above, the present invention monitors the power supply voltage and determines printing, thereby making it possible to print with good quality with the minimum necessary power supply capacity. Furthermore, since the printing of one dot line is divided into multiple prints, there is also the effect of reducing noise.

[Brief explanation of the drawing]

Figure 1 is the principle diagram of a dot line printer, Figure 2
FIG. 3 is a circuit diagram showing the relationship between the hammer driver and the power supply voltage monitoring circuit, FIG. 3 is a conceptual diagram showing the relationship between printing timing and printing operation, and FIG. 4 is a timing chart at that time. 1...Platen, 2...Hammer bank, 3...
Comparator, H ₁ ~ H _o ... Hammer, L ₁ ~ L _o ......
Hammer coil, _R1 , _R2 ...Resistor, a...Output signal of the power supply voltage monitoring circuit, b...Movement direction of the hammer bank, c...Print timing signal, d...Hammer excitation signal, e... Power-supply voltage.

Claims (1)

[Scope of Claims] 1. A method for driving a dot line printer in which a fixing means equipped with a plurality of dot forming means is reciprocated on a paper surface and the paper is fed and printed in synchronization with the reciprocating movement, wherein the printer comprises: a first process comprising a voltage monitoring means for comparing a power supply voltage for driving the dot forming means with a predetermined set voltage, and referring to the voltage monitoring means at each driving time of the dot forming means; In the process of step 1, if the voltage monitoring means indicates that the power supply voltage is higher than the set voltage, printing is performed; on the other hand, if the voltage monitoring means indicates that the power supply voltage is lower than the set voltage, printing is performed. Stopping the driving of the dot forming means and stopping the paper feeding operation for a period required for one reciprocation of the fixing means, and restarting the driving of the dot forming means and the paper feeding operation after the period required for one reciprocation. 2. A method for driving a dot line printer, the method comprising: