JPS6334034B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a failure detection device for a motor-driven printer.

Conventionally, small and inexpensive printers have not performed any special processing even if the motor is locked or the print timing pulse signal is no longer output for some reason. However, if the printer is left in such an abnormal state for a long time, it may cause an irrecoverable failure of the printer. In particular, impact-type printers that print by driving a solenoid coil have a small gap between the head section that holds the solenoid coil and the platen that supports the printing paper, which can cause the printing paper to get caught on the head or the printer fixing section. If the blockage occurs, the motor coil may burn out, the transistors in the motor control circuit may be destroyed, etc.
There is a danger that the fuse may blow out.

The object of the present invention is to be able to detect abnormal conditions when the motor locks up or the print timing pulse signal stops coming out for some reason, and to ignore failures that occur within an acceptable period of time and to continue printing for an unacceptably long period of time. An object of the present invention is to provide a printer failure detection device that can detect only failures that occur.

The key point of the present invention is to monitor the print timing pulse signal generated based on the rotation of the motor while the motor is in a driving state, and to detect that the print timing pulse signal has stopped continuously for a certain period of time.

FIG. 1 is a block diagram showing an example of a motor-driven printer. A processing unit (hereinafter referred to as CPU) 1 that issues print contents and print commands to the printer and a printer control circuit 2 are connected to a CPU interface signal line 20. connected. Printer body 3
is a printing unit 10 and a motor 1 that drives the printing unit 10.
1. A motor control unit 12 that controls driving and stopping the motor 11, a print timing pulse generation unit 13 that outputs a print timing pulse signal A in synchronization with the rotation of the motor 11, a solenoid coil 14, and a solenoid coil control unit 15. There is. When a print command is issued from the CPU 1, the motor 11 starts rotating in response to a command signal S from the motor control unit 12, and the motor 11
As a result of the rotation, a print timing pulse signal A as shown in FIG. 2 is output from the print timing pulse generator 13. The printer control circuit 2 breaks down the print content from the CPU 1 into detailed operations for each timing as shown in FIG. 2, and drives the solenoid coil 14 through the solenoid coil control section 15.
FIG. 2 shows the relationship between the timing pulse signal A and solenoids 1 to 7 when printing the characters "ABC...". In other words, when the print timing pulse signal _T1 is generated, the solenoid 3
~ Solenoid 7, print timing pulse signal
When T ₂ occurs, solenoid 2 and solenoid 5 are
When the printing timing pulse signal _T3 is generated, the solenoid coils are sequentially driven such as solenoid 1 and solenoid 5 to print.

FIG. 3 is a block diagram showing an embodiment of the present invention;
FIG. 4 is a time chart showing the operating waveforms of each part. In FIG. 3, ED is a failure detection circuit, and a pulse loss detection circuit 30 receives the print timing pulse signal A from the print timing pulse generator 13 and detects when this signal A stops.
, an AND circuit 31 , an integrating circuit 32 , and a waveform shaping circuit 33 . Pulse loss detection circuit 3
0 can be constituted by a retriggerable monostable multivibrator, for example. That is, this can be achieved by using the print timing pulse signal A as a trigger signal and making its quasi-stable time longer than the pulse cycle of the print timing pulse signal A. In addition,
If it is necessary to detect the pulse disappearance state sooner, the quasi-stable time is determined to be approximately equal to the pulse period of the print timing pulse signal A, taking into consideration the accuracy of the print timing pulse signal A. The AND circuit 31 inputs the motor drive signal C from the motor control section 12 and the output B from the pulse erasure circuit 30, and inputs the signal D to the integration circuit 32 when the AND condition is satisfied. The integrating circuit 32 integrates the input signal while the signal D is being output, and outputs a continuously changing signal corresponding to the integrated signal to the waveform shaping circuit 3.
3, and when the signal D stops, it returns to the initial state. The waveform shaping circuit 33 can be constructed from a Schmitt circuit. That is, when the signal D exceeds the threshold voltage of the Schmitt circuit (voltage VH in FIG. 4), the signal F is output during that time. In short, the integrating circuit 32 and the waveform shaping circuit 33 together constitute a circuit that detects that the signal D is continuously output from the AND circuit 31 for a certain period of time. This fixed time substantially depends on the time constant of CR when the integrating circuit 32 is configured, for example, by a CR integrating circuit. Some printer failures are short-lived and can be recovered naturally. It is preferable not to detect such a failure as a failure. Therefore, the time constant of the integrating circuit 32 is determined so that failures within an allowable time are ignored and only failures that continue for an unacceptably long time are detected.

34 is a memory circuit that stores and holds that the waveform shaping circuit 33 has outputted the signal F, and returns to the initial state by the reset signal H. This can be achieved by a flip-flop circuit. The figure shows the case where an RS flip-flop circuit is used.
Input signal F to set terminal S, reset signal H
is input to the reset terminal R, and the signal from the output terminal Q is input to the printer control circuit 2. The printer control circuit 2 receives the signal G and outputs a stop command signal ST to the motor control section 12 and the solenoid coil control section 15, thereby controlling the operation of the printer to stop.

The operation will be explained below with reference to FIG. In a normal printing state, the printing timing pulse signal A continues to be output regularly as shown by periods Ta and Tc. Therefore, the AND condition of the AND circuit 31 is not satisfied, so the failure detection circuit ED does not output the signal F.
When the print timing pulse signal A does not appear regularly due to a paper jam, etc., the pulse loss detection circuit 30
outputs an output signal B. Then, the AND condition is satisfied with the motor drive signal C output from the motor control section 12, and the AND circuit 31 outputs the signal D. The integration circuit 32 operates while the signal D is output, and when the signal D is output for a certain period of time Ts or more and the output signal E of the integration circuit 32 exceeds the threshold voltage VH, the memory circuit 34 is activated through the waveform shaping circuit 33. is set, and the memory circuit 34 receives the signal G.
Output. The printer control circuit 2 inputs the signal G and outputs a command signal ST to stop the printing operation to the motor control section 12 and the solenoid coil control section 15.
Stop printer operation. When restarting the printer, remove the direct cause of the paper jam, etc., and then restart the printer. A print command is output from the CPU 1, and the memory circuit 34 is reset by the reset signal H created by this, and the printer returns to normal operation. Return to action. Note that the output of the memory circuit 34 can be effectively used not only to stop the printer but also to activate an alarm.

As is clear from the above description, according to the present invention, it is possible to easily detect abnormalities such as the motor being locked due to a paper jam in the printer. Therefore, by utilizing this, it is possible to prevent the printer from suffering an irrecoverable failure. Furthermore, since the present invention detects printer failure by monitoring the print timing signal, it is possible to detect failures in the event that the printer no longer prints normally due to a failure in the print timing pulse generator. can also be detected. Furthermore, the present invention sets the time constant of the CR integration circuit and the threshold voltage of the waveform shaping circuit so that the flip-flop circuit outputs a failure signal after a predetermined allowable time has elapsed after the print timing pulse signal stops. Therefore, it is possible to obtain a printer failure detection apparatus that can ignore failures within an allowable time and detect only failures that continue for an unacceptably long time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the printer, FIG. 2 is an explanatory diagram for explaining the printing operation of the printer, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. This is a time chart showing the operation waveforms of each part of the . 3: Printer body, 10: Print section, 11: Motor, 12: Motor control section, 13: Print timing pulse generator, ED: Failure detection circuit.

Claims (1)

[Claims] 1 A printing section, a motor that drives this printing section,
In a printer that has a print timing pulse generator that outputs a print timing pulse signal in synchronization with the rotation of the motor, and a motor control section that controls driving and stopping of the motor, the print timing pulse signal is used as a trigger signal, and the print timing pulse signal is used as a trigger signal. A retriggerable monostable multivibrator that sets a stabilization time to be longer than the period of the printing timing pulse signal, detects that the printing timing pulse signal stops, and outputs a signal, and an output signal from the monostable multivibrator. and a motor drive signal from the motor control section, and an AND circuit that detects the establishment of an AND condition of these two signals and outputs a detection signal; a CR integrating circuit that integrates the detection signal while the detection signal is being outputted, outputs a continuously changing integral signal corresponding to the integration signal, and returns to the initial state when the detection signal stops;
A waveform shaping circuit that inputs an integral signal from the CR integrating circuit and outputs a signal when the voltage of the integral signal exceeds a threshold voltage, and inputs an output signal from the waveform shaping circuit;
a flip-flop circuit that stores the output signal and outputs the signal as a failure signal; A failure detection device for a printer, characterized in that a time constant of a CR integration circuit and a threshold voltage of the waveform shaping circuit are set.