JPH07290730A - Printer fitted with protecting circuit - Google Patents

Abstract

PURPOSE:To protect a printer control circuit and provide easy after service properties by always monitoring voltage in the protection of the printer control circuit and applying resetting to the printer control circuit instantaneously when abnormal voltage is generated. CONSTITUTION:A voltage detection circuit 3 is added to a part of a printer control circuit 2 and an output terminal enabling the transmission of a reset signal to the control circuit at the time of the abnormality of voltage is provided. Therefore, abnormal voltage is always monitored during the printing operation of a printer and resetting is applied to the control circuit instantaneously at the time of abnormal voltage not only to enhance the safety of the printer but also to minimize the damage of the printer control circuit 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to protection of electronic control circuits in printers.

[0002]

2. Description of the Related Art In printing of a printer, it is used in a wide variety of work environments in various working environments. In a bad environment (especially in a place where there is a lot of metal dust), the metal dust will be inside the control circuit board. There was a problem that the electronic device on the circuit was destroyed due to a drop in the circuit and a short circuit between the circuits.
Therefore, the conventional printer has a built-in circuit for detecting and protecting the abnormal voltage of the circuit.

FIG. 3 is a flow chart for detecting an abnormal voltage. Before starting printing, the voltage in the circuit is measured, it is judged whether an abnormal voltage is generated, and if an error is detected, an error is displayed and the printing operation is started. I was trying not to.

However, since the judgment is made before the start of printing, even if an abnormal voltage is generated during printing for some reason, the protection operation is not carried out and the control circuit is destroyed, resulting in unusable operation.

[0005]

In the prior art, since an abnormal voltage is detected before printing, even if an abnormal voltage occurs during printing, it cannot be protected and the entire control circuit is destroyed, resulting in a repair cost. It was expensive and required a great deal of manpower to repair. Therefore, the present invention is intended to solve such a problem, and an object of the present invention is to always protect the control circuit before and during printing.

[0006]

A printer with a protection circuit according to the present invention comprises: a) a printer for printing characters, symbols, etc. on paper using a wire dot head or an inkjet head, a thermal head, etc., and b) a printer. The power supply voltage of the electronic control circuit for controlling the circuit is constantly monitored to detect an abnormal voltage, and at the same time, the abnormal voltage is instantaneously blocked to protect the circuit.

[0007]

Since the present invention has the above-mentioned structure, when there is no abnormality due to the operation of the protection circuit, the printer prints and the abnormal voltage is immediately blocked when the abnormality occurs. Therefore, the control circuit is protected and the electronic element can be prevented from being destroyed.

[0008]

EXAMPLES The present invention will be described in detail below based on examples.

FIG. 1 is a block diagram of a printer with a protection circuit according to the present invention. 1 is a power supply circuit, 2 is a printer control circuit, 3 is a detection protection circuit for monitoring an abnormal voltage and blocking a voltage output from the power supply circuit. The protection detection circuit constantly monitors the voltage and detects an abnormal voltage. Then, the protection detection circuit sends a reset signal to the reset terminal of the printer control circuit. When the reset signal of the printer control circuit is input, all the operations of the printer are stopped and the electronic elements are protected.

FIG. 2 shows a part of the logic circuit of the protection circuit of the printer with the protection circuit according to the present invention. Reference numeral 5 is a voltage comparator for detecting an abnormal voltage, 6 is a bistable multivibrator for holding the abnormal signal and outputting a reset signal to the printer control circuit, and 7 is a reset for initializing the protection detection circuit. A switch, 8 is a reference power source for detecting abnormal voltage, 9 is an input terminal for detecting abnormal voltage, and 10 is an output terminal for outputting a reset signal.

FIG. 4 is a flow chart of the abnormal voltage detection protection circuit of the present invention. The voltage is constantly detected regardless of whether it is before printing or during printing, so if there is no abnormality, the printer prints and the abnormal voltage is detected. At that time, the abnormal voltage is instantaneously stopped and the printer is stopped.

This protection circuit need only have a voltage detection input line, a reset signal output line, and a circuit drive power supply line, and since the circuit is simple, it can be sufficiently mounted in an empty space in the circuit board. .

[0013]

As described above, according to the configuration of the present invention, the printer abnormal voltage detection circuit does not detect the voltage before the start of printing as in the prior art, but always detects the voltage, which is a very expensive printer. It greatly contributes to minimizing the repair cost without destroying the control circuit. Further, since this detection circuit can be mounted with several parts in an empty space of the printer control circuit, it is not necessary to change the shape of the printer and the cost increase can be minimized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a signal transmission circuit of a printer according to the present invention.

FIG. 2 is a block diagram of an abnormal voltage detection circuit according to the present invention.

FIG. 3 is a flowchart of a conventional abnormal voltage detection sequence.

FIG. 4 is a flowchart of an abnormal voltage detection sequence according to the present invention.

[Explanation of symbols]

 1. ． ． ． ． Power supply circuit 2. ． ． ． ． Printer control circuit 3. ． ． ． ． Abnormal voltage detection protection circuit 4. ． ． ． ． Printer mechanism 5. ． ． ． ． Voltage comparator 6. ． ． ． ． Bistable multivibrator 7. ． ． ． ． Reset switch 8. ． ． ． ． Reference power supply 9. ． ． ． ． Input terminal 10. ． ． ． ． Output terminal

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Claims (1)

[Claims] 1. A) A wire dot head, an ink jet head, a thermal head or the like is used to print characters on paper or the like.
In printers that print symbols, etc. b) Provided with a function to constantly monitor the power supply voltage of the electronic control circuit that controls the printer and, when an abnormal voltage is detected, immediately cut the power supply voltage to enable protection of the control circuit. A printer with a protection circuit characterized by the above.