JPH0461783B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a printer device.

Conventional configuration and its problems Conventionally, in order to prevent continuous overcurrent of the printer head section of a printer device, that is, the head and its drive source (motor, etc.), a system including a printer device is reset as shown in Fig. 1. A circuit was set up. In the figure, 1 is a system, 2 is a reset circuit, 3 is a printer control board of the printer device, 4 is its print mechanism, 5 is a power supply circuit,
Reference numeral 6 indicates other related equipment, and as shown in the figure, the reset circuit 2 is configured to utilize fluctuations in the AC power supply. The reason for this is that it is possible to detect fluctuations in the power supply voltage more quickly by detecting fluctuations in the AC power supply than by detecting fluctuations in the power supply voltage of the printer device.

By the way, such a reset circuit is a reset circuit that detects fluctuations in AC power supply when the manufacturer of the printer device and the manufacturer of the system using it are the same, or when the system manufacturer is familiar with the printer device. However, if the printer manufacturer and the system manufacturer are different, and the system manufacturer does not prepare a reset circuit, there is a problem that the printer head or drive source may be damaged. Furthermore, when the same printer device is used by multiple system manufacturers, it can be said that the total cost will be lower if the printer manufacturer prepares a reset circuit.

Purpose of the Invention Therefore, the present invention prevents troubles related to reset circuits between printer device manufacturers and system manufacturers, and reduces the total cost when the same printer device is used by multiple system manufacturers. The purpose of the present invention is to provide a printer device that can be lowered.

Composition of the Invention This invention provides a printer head unit, a power supply for driving the printer head unit, and a microcomputer, etc. that controls the printer head unit when the power supply drops, and outputs a reset output signal before the voltage reaches normal operating voltage. and a reset circuit that detects a drop in the voltage of the power supply by comparing it with a reference voltage that is the sum of the forward voltage drop of the diode and the base-emitter voltage of the transistor. The power supply voltage detection circuit has a charging current limiting resistor, a capacitor, and a diode connected in parallel to the charging current limiting resistor such that the anode side is the positive side of the capacitor. a capacitor charging/discharging circuit that charges the capacitor through the charging current limiting resistor when a drop in the power supply is not detected and discharges the capacitor through the diode when the power supply voltage detection circuit detects a drop in the power supply; and a terminal of the capacitor. and an output circuit that outputs a reset output signal when the voltage is less than the forward voltage of the diode of the capacitor charging/discharging circuit, and stops the reset output signal when the voltage is higher than the forward voltage of the diode of the reference voltage. be.

Specifically, a reset circuit for turning off the printer head section is provided in the printer device, that is, its printer control board. Therefore, no trouble occurs even if the system manufacturer does not prepare a reset circuit, and the total cost can be reduced when the same printer device is used in a plurality of systems.

As an embodiment, this reset circuit includes a reset signal input circuit, a capacitor charging/discharging circuit, a hysteresis setting circuit, a reference voltage generation circuit, a power supply voltage detection circuit, and an output circuit. The comparator, which consists of the reference voltage generation circuit and power supply voltage detection circuit, continues to output a reset output until the power supply voltage reaches the normal operating voltage of the microcomputer or other IC (integrated circuit) that controls the head section. At times, the reset output should be output before the IC's normal operating voltage is exceeded. In addition, in the capacitor charging/discharging circuit, when the power supply voltage drops, the side of the charging current limiting resistor that is not connected to the capacitor is set to a low potential, and a diode is connected in parallel to the charging current limiting resistor, and its anode is connected to the positive side of the capacitor. do. A reference voltage generation circuit is constructed of active elements such as diodes, which number is greater than the number of diodes used here. With these configurations, the reset circuit outputs a reset output not only when a reset signal is input, but also when the power is turned on and when the power goes down, and the head and drive source are protected from damage caused by continuous overcurrent, including in the IC's unstable voltage range. can be prevented.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIGS. 2 and 3. First, in FIG. 2, 7 is a reset signal input circuit, 8 is a capacitor charging/discharging circuit, 9 is a hysteresis setting circuit, 10 is a comparator, 11 is a reference voltage generation circuit, 12 is a power supply voltage detection circuit, 13 is an output circuit, 14 is an input terminal, and 15 is an output terminal. Also, Fig. 3 shows a concrete example of the circuit, 16 to 19
are PNP transistors, 20 to 23 are NPN transistors, 24 and 25 are diodes, 26 is a capacitor, 27 to 46 are resistors, 47 is a DC power supply voltage terminal, and 48 is a ground terminal. In this circuit example, the reset input signal (14) and reset output signal (15)
is explained using negative logic.

When the power is turned on, the power supply voltage is first applied to the resistors 37 and 38.
The detected voltage at point Q is detected by diode 2.
V _F (forward voltage drop) of 5 and V _BE (base-emitter voltage) of the power supply voltage detection transistor 22
When the time limit is exceeded, transistor 22 is turned on and transistor 17 is subsequently turned on. As a result, capacitor 26 is charged from transistor 17 through limiting resistor 32 . The voltage at point P is divided by V _F of diode 25, V CE (collector-emitter voltage) of transistor 22, and V _CE (collector-emitter voltage) of transistor 21.
When the voltage exceeds V _BE (base-emitter voltage), transistor 21 turns on, and then transistors 18 and 19 turn on. As a result, although the output terminal 15 has continued to output a reset signal, the reset is canceled and the circuit is reset until it reaches the normal operating voltage. Further, in order to prevent malfunction, when the transistor 18 is turned on, the transistor 23 is turned on, and the reference voltage has hysteresis by the amount of V _F of the diode 25.

When the power supply drops, when the voltage at point Q drops below V _CE (collector-emitter voltage) of transistor 23 and V _BE of transistor 22, transistor 22 is turned off, transistor 17 is subsequently turned off, and the voltage at point R is lowered. As the voltage of capacitor 2 decreases,
6 is rapidly discharged through diode 24. At point P, the voltage drops to V _F of diode 24. On the other hand, when the transistor 22 is turned off, the emitter current of the transistor 21 stops flowing, and the transistors 18, 19, and 23 are turned off, and a reset signal is outputted before the output terminal 15 reaches the normal operating voltage. Further, when the transistor 23 is turned off, the reference voltage increases by V _F of the diode 25.

Even if the power supply voltage becomes normal again, the voltage at point P is only for V _F of diode 24, while the reference voltage is for diode 25, which has a larger number of active elements.
V _F , V _CE of transistor 22, and V _BE of transistor 21, so a reset signal is output to the reset terminal while charging the difference.

When a reset signal is received from the outside, transistor 16 is turned on, transistor 20 is turned on, capacitor 26 is discharged, transistors 21 and 19 are turned on, and a reset signal is output.

In this way, when receiving a reset signal,
When the power is turned on, a reset signal can be output to prevent the printer head and drive source from being damaged even when the power supply voltage drops due to a momentary power outage. In particular, when the transistor 22 detects a drop in the power supply voltage and turns off, and the transistor 17 turns off, the capacitor 2
The charge accumulated in the output transistor 19 is rapidly discharged through the diode 24 to the V _F of the diode 24, but when it becomes normal again, the output transistor 19 is immediately discharged.
A diode 25 is attached to prevent the capacitor 26 from turning on, and when the capacitor 26 starts charging, the terminal voltage at the P point of the capacitor 26 becomes V _F of the diode 24.
Minutes to V _F of diode 25, transistor 2
After being charged to V _BF of 1 and V _CE of transistor 22, transistor 21 is turned on, transistor 19 is turned on, and the reset is released. Therefore, this time is reliably supplied to the microcomputer as the reset pulse width. A microcomputer requires a reset pulse time, and a whisker-like reset pulse may cause the microcomputer to run out of control. However, the present invention can supply a stable reset pulse width to the microcomputer even during a slight power failure.

Note that this reset circuit is constituted by a thick film hybrid integrated circuit and is mounted on the printer control board.

Effects of the Invention As described above, the printer device of the present invention can generate a reset output signal when the power is turned on and when the power goes down, and can generate a stable pulse-like reset signal even in the case of a momentary power outage. Therefore, even if the system manufacturer does not give any consideration to damage caused by continuous overcurrent in the head and drive source, there will be no problem, and the total cost can be reduced when applied to multiple systems. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a specific circuit diagram thereof. 3... Printer control board, 4... Printer mechanism (head section, drive source), 7... Reset signal input circuit, 8... Capacitor charging/discharging circuit,
9...Hysteresis setting circuit, 10...Comparator, 11...Reference voltage generation circuit, 12...Power supply voltage detection circuit, 13...Output circuit, 14...Input terminal, 15...Output terminal, 16-23... ...Transistor, 24, 25...Diode, 26...Capacitor, 27-46...Resistor, 47...Power supply voltage terminal.

Claims (1)

[Claims] 1 comprises a printer head section, a power source for driving this printer head section, and a reset circuit that outputs a reset output signal before a microcomputer or the like that controls the printer head section reaches a normal operating voltage when the power supply drops. , the reset circuit includes a power supply voltage detection circuit that detects a drop in the voltage of the power supply by comparing it with a reference voltage that is the sum of the forward voltage drop of the diode and the voltage between the base and emitter of the transistor, and a charging current limiter. The power source voltage detecting circuit includes a resistor and a capacitor, and a diode connected in parallel to the charging current limiting resistor such that the anode side is the positive side of the capacitor. a capacitor charging/discharging circuit that charges the capacitor through a charging current limiting resistor and discharges the capacitor through the diode when the power supply voltage detection circuit detects a drop in the power supply; A printer device comprising an output circuit that outputs a reset output signal when the forward voltage of the diode of the circuit is lower than the forward voltage of the diode, and stops the reset output signal when the reference voltage is higher than the forward voltage of the diode.