JPS5929174A - Apparatus for controlling printing of thermal head - Google Patents

Abstract

PURPOSE:To prevent the supply of overcurrent to a thermal head, by utilizing a signal for controlling the longest current supply time of the thermal head as the drive power sources of a thermal head driver or a gate circuit in combination. CONSTITUTION:A printing signal (b) is supplied to a driver 4 and the synchronous signal of said signal (b) is supplied to a monomultiplier 1 to supply high level output C to the driver 4. This output C is the enable signal of the driver 4 while simultaneously acts as a power source and, when the printing signal (b) is supplied, the driver 4 is operated to turn the output of a transistor TR1 ON and, thereby, a transistor TR2 is electrically connected to operate the heat generating element of a heat 5. Even if a printing signal D succeeds an ON-state for a longtime by abnormal connection, it is turned OFF by the enable signal C after the time T1 determined by the characteristics of a condenser 2 and a registor 3 is elapsed and the trandistor TR2 is disconnected to stop the operation of the driver 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thermal printing control equipment suitable for recording devices, facsimile machines, etc., and in particular, to prevent abnormal energization to the server.

In general, in a thermal recording type printing device using a thermal hent, the printing IiM degree control is performed within the pulse width f)D
It is controlled so that the amount of deer added to the thermal hend remains constant. Therefore, if a difference occurs in the device and the pulse width becomes larger than the standard i1ti, the heat generated by the thermal 2V1-
When overpower is applied to the -n1-, it often happens that the -n1-'s noj(Ii or yυ〈urine or sometimes it is destroyed in an instant.) Conventionally, this inconvenience was In order to prevent this, it has been proposed that, for example, an AND circuit should be provided to take the AND of the enable signal and the print signal. ) could not be done.

The purpose of the present invention is to eliminate the shortcomings of J: 1AXL, and to control 11 the longest energization time to thermal and 71'.
1 (By having No. 4 serve as a thermal head drive dryer or a drive power source for one of the cables 1-1ijl, it is possible to use a thermal head drive unit to sufficiently prevent deer from entering the thermal head.) 1. Providing a printing control device.

Hereinafter, the present invention will be explained with reference to the tooth shown in FIG. 1.

FIG. 1 shows an example of the configuration of the thermal print control device of the present invention, where 1 is a medium-stable multi-7ζ brake (
(hereinafter referred to as "mono-multi"), and outputs a high level output C at a predetermined 11'? Ill T, output as much as you want. The 11λ terminal end of this monomulti 1 is connected between the 1st capacitor 2 and the resistor 3, and the power supply Vcc is applied to the monomulti 1 through the resistor 3. 4 is a thermal head drive driver that drives multiple thermal heating elements individually, and each of the 7 phantom transistors TR
, and TR, and 11[, anti′, A+VR, and R
2. The former transistor TR, is ρnp)
I'j l-ransisk, and all its emitters are supplied with the output C of the monomulti 1 to the -F1, and the print signal S, which is connected to the center of each pair, is supplied to its pace through the resistor R1. Supplied individually. The transistor TR in the rear is an npn with an emitter installed! T,'il Landisk,
5 is a thermal head having a plurality of heating elements (heaters), one end of which is connected to the collector of the corresponding transistor TR2 through the resistor R2. and the other end is connected to the power supply V.Here, the output C described in L is a pull signal for controlling the maximum turnaround time T to the thermal head 5, and at the same time it is a pull signal for driving the thermal head. The drive of the driver 4 becomes 'IIf a:j.

FIG. 2 shows examples of signal waveforms in each part of FIG. 1. Next, an example of the operation of the apparatus 1'1 shown in FIG. 1 will be explained with reference to FIG.

Multiple print messages sent from the control circuit (not shown)? At the same time as supplying b to I-lime 4, printing a is generated in synchronization with the output of 4-li-b (i.
supply to. The monomulti 1 is operated using this inter-period signal a as a trigger mechanism, and a high level output C is supplied to the driver 4. This output C acts as an enable signal for the driver 4 and also as a power source, so when the print number 411 is supplied, the driver 4 is activated and the output of the transistor TR is turned ON. As a result, the transistor TR is made conductive, and the source v is turned on, causing the heating element of the thermal head 5 to generate heat, thereby allowing printing to be performed.

At this time, the pulse 'l'f+i is controlled so that when the time T2 reaches the 'ik force required for printing, the printing number 417 is turned 0FF (ilik force), so the printing density can be kept constant. . Also, from Mono Multi 1 to i・Lime 4
4"i '!'+C sent to the capacitor 2 and resistor 3 for a predetermined time T1 determined by
'of! At that time, as shown in Fig. 2, maintain the relationship of T, >T2, and print 1. - The length of the predetermined time T1 is set so that the operating time T2 of the signal No. 1 sufficiently guarantees the operating time T1 of the signal C. As a result, even if the print signal 1]N continues due to the normal operation of the control circuit shown in the figure, the enable No. 111C is turned off at an appropriate time T after the set time T2 has elapsed, so that the transistor TR , becomes non-conductive and i・lie/<
The operation of step 4 stops. Thus, the usual long-term transit to the thermal head 5 is reliably prevented, and at least for a time T, the fever of the head 1-5 is interrupted. Furthermore, since the power supply side of the driver 4 is controlled by T2 between 114i, even if the input terminal of the driver 4 is damaged, the output of that driver 4 will always be turned OFF, and the damage to the thermal head 5 will be reduced to 1. - Minute defense +
1 is given.

Below 1. As explained above, according to the present invention, the overcurrent limit control is carried out on the supply side of the thermal hent dryer/gate circuit through the mono-multiple pipe break, so that the gate circuit or the driver is controlled. The input side may be damaged or the supply may be damaged. Even if an unstable state occurs at the time of rising or falling, abnormal communication to the thermal head side can be prevented within 1 minute.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of the device of the present invention, and FIG. 2 is a timing chart showing examples of waveforms of A and -1 Gin in each part of FIG. 1. 1...I'lj stable multivibrator, 2nd capacitor. 3...Resistor, 4...Try/to, 5...Thermal head. TR,...pnp type (・ransistor, TR,...n
PN type transistor, R,, R,...Resistor, a...Return signal, b...Print A, 1 output, C...Output (゛Power supply k IT4 enable No. 17) ,T, ,T,...operation time. Fig. 2 Signal C---T1----1

Claims (1)

[Claims] Controls the maximum energization time of thermal/2nd
J: Output generating means that generates an output that also serves as a source of output in synchronization with a print signal, and a logic between the output and the print signal J! ! ! and a driving means for energizing the thermal head (1111) by operating at the same time as the product (Nfi).