JPS58134755A - Wire dot printer - Google Patents

Abstract

PURPOSE:To obtain a wire dot printer capable of suppressing the overheating of a head by lowering the drive frequency of the head by a method in which the lowering of power source voltage is detected and the reception is limited. CONSTITUTION:Signals from a power source voltage level detection circuit 21 and a peak voltage holding circuit 22 of power source voltage are compared in a comparator circuit 23, and when power source voltage drop exceeds a fixed value by overdense printing, output is given to the comparator circuit 23. When an overdense printing detection signal due to power source voltage drop for a fixed period is output at an integration circuit 24, it is compared with a reference voltage at the comparator circuit 25, and when the reference value is exceeded, the overdense printing alarm is transmitted to a centralized processor (CPU)26. In the CPU26, the alarm signal is watched and the slow-down of reception speed is indicated to an interface control circuit 27.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wired printer that performs high-density and high-speed printing.

Generally, printers are required to print as quickly as possible. On the other hand, if each drive is driven continuously at a high speed above a certain level, heat is generated, and if this is ignored, the temperature will rise rapidly and the head will eventually catch fire.

For this purpose, it detects when the head reaches a predetermined temperature determined experimentally, and then slows down or temporarily stops printing to prevent the head from overheating. was being treated.

FIG. 1 shows a configuration diagram of a conventional wire dot printer.

In the figure, 1 is an interface control circuit, 2 is a print timing control circuit, 3 is a wire head driver circuit, and 4 is a wire head driver circuit.
A is a print head, and 4b is a temperature detection sensor. In the case of high-density continuous printing, the temperature detection sensor 14b detects overheating of the print head 4&, and the print timing control circuit 2 decelerates the printing speed. Alternatively, printing is stopped to suppress the temperature rise of the print head 4a.

However, a wide range of data is received, from data similar to so-called peta-type printing, which requires continuous driving of all dots, to data with normal character i degrees.

Therefore, in the above-mentioned method of detecting the temperature of the head 4a, if the temperature is detected when the head temperature rises slightly according to the level of the tapping, the printing speed of normal data will slow down. On the other hand, if you set the level to normal data and leave it alone until the head temperature rises considerably, the head will overheat when it receives flat data. After this happens, in order to lower the temperature to a predetermined temperature, printing becomes impossible for a considerable period of time.

In other words, with the conventional method of detecting head temperature, even if the temperature is detected in several stages, the best course of action is to determine the next data to be received and take appropriate countermeasures. I couldn't get it.

Furthermore, when performing continuous high-density printing, there was also a problem with the capacity increase and heat generation of the power transformer.

The overloading system solves these conventional drawbacks; if the dot drive is overloaded, the power supply voltage will drop;
Then, by utilizing the fact that an overload is associated with an excessively high head temperature, it detects a drop in the power supply voltage and limits reception, thereby controlling the head drive frequency (
(in terms of time), thereby suppressing overheating of the head. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing a first embodiment of the wire dot printer of the present invention, in which 21 is a power supply voltage level detection circuit, 22 is a power supply voltage peak voltage holding circuit,
The comparison circuit 23 compares the two. When the stain source voltage drop exceeds a certain value due to overcrowded printing, an output is obtained from the comparator circuit 23.

Reference numeral 24 is an integrator circuit for this output, which functions to ignore instantaneous voltage drops and output an overcrowded printing detection signal based on voltage drops over a certain period of time. The output of the integrating circuit 24 is compared with a reference voltage by a comparison circuit 25, and when the reference voltage is exceeded, an overcrowding printing alarm condition is transmitted to the central processing unit (CpU). The CPU 26 looks at the alarm signal and instructs the interface control circuit 27 to reduce the reception speed.

FIG. 3 is an example of a circuit for detecting overcrowded printing, and FIG. 4 is a diagram showing one waveform of each part. In Figure 3, resistance R1
The divided potential a of the resistor R2 and the resistor R2 indicate the fluctuation of the driver power supply voltage, and the divided potential of the resistor R3 and the resistor R4 is the level at which the voltage drop of the divided potential a is compared with the peak voltage of the driver power supply as a reference. It shows.

When a large number of shear wires are driven by the through print head drive signal X shown in FIG. The partial voltage potential of is reversed with the potential of S. Third
The output of the comparator circuit Ql shown in the figure has the waveform shown in Figure 4C, and becomes open at the portion where the divided voltage potential a is low. Therefore, charge is accumulated in the capacitor C2 of the CR integration circuit, and its potential is It rises as shown in Figure 4d.

When the reference voltage e is exceeded by charging for more than a certain period of time, the comparator circuit Q2 is inverted, and the overcrowded printing alarm signal shown in FIG. 4f is obtained.

When the printing density is low and the power supply voltage drop is small, the charge accumulated in the capacitor C2 in FIG. 3 is discharged through the resistor R6, so that instantaneous overcrowded printing can be averaged out. Therefore, when the CPU 26 detects overcrowded printing, it instructs the interface control circuit 27 shown in FIG. 2 to reduce the receiving speed (5) Outputs the DELAY signal. The operation of reducing the receiving speed will be explained in FIG.

FIG. 5 is a flowchart showing the operation of reducing the printing data reception speed when an overcrowded printing alarm is detected.

In the print data reception cycle, if the CPU is ready to receive data, the CPU turns on the receivable signal. When this signal turns ON, a one-shot timer for a certain period of time is started. This timer is ignored when printing is not overcrowded, but
If the CPU turns on the DELAY command signal due to the overcrowded printing alarm 1-, the RDA (receivable) signal is turned on on the circuit side until the one-shot timer turns off.
Hold N. RDA externally when timer turns OFF
Turn on the signal. The print data sending side looks at the RDA and
Outputs data and RDP (reception command). CPU is R
It receives data by looking at the DP, inputs it to the printing node, and turns off the RDA. Thereafter, the process moves to a permanent print data reception cycle in which RDP is turned off. Therefore,
The reception speed can be reduced by a one-shot timer.

(6) The interface control circuit 27 shown in FIG. 2 starts a one-shot timer at the timing when the data reception enable signal from the CPU 26 turns ON, and when the DELAY signal turns ON, sends a data reception enable signal (RDA) to the data transmitting side. O
The reception speed is reduced by delaying N until the count end of the one-shot timer.

In this way, it is possible to set the driving frequency according to the received data, thereby enabling efficient printing.

As explained above, in the first embodiment, the output state of overcrowded print data can be determined in a short time, so there is an advantage that the received data can be suppressed so that the print head does not become hot.

In addition, by avoiding continuous overcrowded printing, the heat generation of the stain source transformer is suppressed. Although the print alarm detection signal slows down the reception speed and suppresses the temperature rise of the print head, the same effect can be obtained by slowing down the print speed by detecting the alarm signal. In other words, in the case shown in Fig. 6, when a step motor is used as the space motor and printing is performed according to a four-pass switching command from the CPU, when an overcrowding alarm is detected, the motor is decelerated to a stop and then retreated by the approach distance.◇Then it is accelerated. At constant speed, printing is performed, but when this constant speed/main pulse switching is slowed down, the printing speed is reduced because the space pulse motor switching and printing timing are synchronized.

In Figure 6, 6 is the CPU, 62 is the external timer, and 63 is the CPU.
is a motor driver, and 64 is a step motor that is spaced by a pulse switching command from the CPU 61. Note that 65 is a print timing control circuit, 66 is a head driver, and 67 is a print head.

That is, when the CPU 61 detects an overcrowded printing alarm such as the driver power supply voltage drop detection circuit 11□11]60, it starts the external timer 62 and slows down the speed within the predetermined time at timer 1 of this timer. It is determined that it is the print mode, and the speed of the step motor 64 is reduced via the motor driver 63 to reduce the print density.

As explained in detail above, the present invention can set the driving frequency according to the received data, so it is possible to suppress the heat generation of the print head in case of overcrowded printing. It has the advantage of not requiring any restrictions regarding the creation of print data; - there is a large degree of freedom in system design;

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional wire dot printer, Fig. 2 is a block diagram of an embodiment of the invention, Fig. 3 is a circuit diagram of an embodiment of the invention, and Fig. 4 is a waveform diagram explaining Fig. 3. , 5th
The figure is a flowchart for explaining an embodiment, and FIG. 6 is a block diagram for explaining another embodiment. DESCRIPTION OF SYMBOLS 1... Interface control circuit, 2... Print timing control circuit, 3... Driver circuit, 4a... Print head, 4b... Temperature detection sensor, 21... Power supply voltage level detection circuit, 22 ...Power supply voltage peak voltage holding circuit, 23.25...Comparison circuit, 24...Integrator circuit, 26...CPU, 27...Interface control circuit, 60...Driver power supply voltage drop detection circuit, 61
(9) CPU, 62... External timer, 63... Motor driver, 64... Step motor, 65... Print timing control circuit, 66... Head driver, 67...
・Print head O (10) Fig. 4 Fig. 6 Fig. 5

Claims (1)

[Claims] A comparator circuit compares the outputs of the stain source voltage level detection circuit and the peak voltage holding circuit of the power supply voltage to detect a drop in the power supply voltage rail.The output is then passed through an integrating circuit, further compared with a reference voltage, and integrated. A wire dot printer characterized in that when the output of a circuit exceeds a reference voltage, an overcrowded printing alarm signal is outputted to instruct a reduction in reception speed.