JPS5857986A - Printer - Google Patents

Abstract

PURPOSE:To obtain a printer which can detect overload by generating a timing pulse in synchronism with a travelling of a printing head and utilizing the cycle of this pulse. CONSTITUTION:When a driving circuit 4 receives a driving control signal (a) from a CPU3 and energizes a motor and makes a printing head travel, a timing pulse is emitted from a timing pulse generator 1 with longer cycles at first, gradually shorter cycles secondly and steady-state cycles at last in synchronism with the travelling. A monostable multivibrator 6 to which the pulse is input makes L level output under the steady-state travelling, while a monostable multivibrator 7 to which the signal (a) is input outputs L level under nonsteady- state travelling immediately after the motor driving and H level output under steady-state travelling, while the outputs of the vibrator 6, 7 are input into an AND gate 8 and inhibit detection under nonsteady-state travelling immediately after the motor driving. When entering into the long pulse cycle due to an overload, the outputs of the vibrator 6 and gate 8 becomes H level and input into the AND gate 9 together with the signal (a), and a stop signal is transmitted from the CPU3 by an output of the gate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a printing device 1t+ζ that generates timing pulses in synchronization with the running of the print head. The present invention relates to a detection device for when the print head stops due to pressure generation and stiffness (hereinafter referred to as overload).

Conventional overload detection methods include inserting a resistor between the print head drive motor and the motor's @-circuit threshold, detecting the current based on the voltage across this resistor, and detecting the motor load based on this current. There is a way. For this purpose, in order to reduce resistance loss, the resistance value must be as small as possible. As a result, the fluctuation voltage when an overload or the like is applied becomes smaller, and the amplification degree of the amplifier must also be increased, which increases the variation in the operating point of the circuit. Furthermore, if the motor servo narrow path is driven by a PWM method.

An integrating circuit will also be required.

In addition, the normal time for the head to travel between two points is set, and in the event of an abnormality, the head cannot be determined even after that time has passed.
It is also a method that uses a timer to detect when the target point has not been reached. However, this takes time until an abnormality occurs and the overload detection device operates.

The present invention solves these problems.

Overlow F using the period of the timing pulse signal
The configuration of the present invention will be explained below based on the drawings showing one embodiment thereof.

A timing pulse generator (7) generates a timing pulse in synchronization with the running of the head, and (7) an overload detector (u, ca) that detects an overload by detecting the cycle of the signal of the timing pulse generator (1). > is a program stored type microprocessor (hereinafter abbreviated as CPU), which inputs the signal from the overload detection circuit (2) as an interrupt. (to) is an overload can circuit 7 which is controlled by a mark and inhibits the signal from the overload detection circuit (2) when the print head is stopped or started.

Next, the operation will be explained based on FIG. 2, which shows the main parts of the above-mentioned configuration as electrical paths, and FIG. N1, which shows waveforms as time charts. In FIG. 2, the parts with the same reference numerals as in FIG. 1 are the same Jl parts as those in FIG. 111. C.P.
When a drive-side signal (indicated by il start point & tIliiii in Fig. , the print head runs.

Then, the timing pulse generator that is synchronized with this...
Therefore, the timing pulse shown in Ha diagram (b) is produced. This signal has a long cycle immediately after startup, and gradually becomes shorter (it becomes a constant cycle indicated by ip in Figure 1), and is input to the monostable multivibrator (11). The Q output of is the first ME (
As shown by 8tL in FIG.

) becomes L level. Here Tc is set longer than 1) n
After starting the motor, the Q output of the monostable multivibrator (6) will be as shown in Fig. 8 (c).
), it remains at L level.

In addition, the drive 11 control signal for the print head running speed output from the CPU (aJ) is simultaneously transmitted to the monostable multivibrator (η.
As shown in Figure (Excellent), at the same time as the drive side signal of the The Q signal from this monostable multivibrator (<1) and the η signal from the monostable multivibrator (1) are sent to the AND gate (8). It is at the L level from the dynamic traveling start point. Here, an overload is applied at point B in Fig. 8, the running speed of the motor decreases, and the period of the signal of the tie and electric Suge pulse shown in Fig. 8 (b) is longer than Tc (when the monostable multi-by-break ( The ?output of 2) becomes the ■level Jl/ as shown in the th. AND gate (input to and done by the above C)
K of the print head running motor output from Pυ(2)
Since the m@ control signal is also input, the output is at the high level only in the event of overload, as shown in the gS diagram (g).

This signal is inputted to the above-mentioned cr as the input signal, and since the motor stop signal is immediately output from crυ(3), the print head stops at five points in the jIB diagram.

As described above, according to the present invention, overload is detected from the period of the timing pulse signal.

Since the n button detection is prohibited for a certain period of time before the print head wakes up and moves to normal running, the accuracy can be immediately checked only when braking force is applied to the print head from the print head or an abnormality occurs in the motor drive circuit, etc. It can be easily detected. Furthermore, when this detection output is directly input to the CPU as an interrupt signal as in this embodiment, the CPU interrupts the instruction being executed and executes another predetermined program, resulting in faster response and less effective results. Remarkable.

[Brief Description of the Drawings] Figure N1 is a block diagram of an embodiment of the present invention.
The Iz diagram shows the main part of the electrical circuit, and the eighth factor is the time chart.
Motor drive circuit 1 (5J-$ -/(-load cancel circuit

Claims (1)

[Claims] 1. A pulse generator is provided that generates a timing pulse in synchronization with the running of the print head, and a detection circuit is provided that uses the period of the timing pulse to detect an abnormality when the head is running, so that the print head is running normally. A printing device characterized in that the detection circuit operates only inside.