JPS592862A - Fire checking system - Google Patents

Abstract

PURPOSE:To provide a fire checking system with a reduced load of a processor by discriminating whether a value reaches as prescribed which is connected at each check timing to indicate the operating condition of a driver in a magnet. CONSTITUTION:A sampling check SCLK corresponding to a sampling period (e) is applied to a counter 4 to check for the output of a fire checking circuit 1, namely, whether an operation amplifier 7 outputs VL or not. When an abnormality occurs, the output of the fire checking circuit 1 always gives VL, which is transmitted to an inverter 5 via an input port 2 to be applied to the counter 4. The counter 4 counts and outputs the sampling clock SCLK to a comparator 6. When a character pulse CP is transmitted to the comparator 6, the comparator 6 compares the current countings with the threshold H and generates an alarm of abnormality when they are larger than the value H.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a fire check method for detecting malfunction of a driver such as a magnet of a dot matrix printer.

(2) Prior Art and Problems For example, in a dot matrix printer, dot printing is performed by driving a dot bin with a magnet. Therefore, if there is an abnormality in the head magnet drive system that drives the magnet during its operation, accurate dot printing control cannot be performed, so abnormality in the head magnet drive system is detected.

Conventionally, when performing abnormality detection, the output voltage of the driver is detected, and when the output voltage is originally at the NO level, it is determined whether the output voltage is at the 4- level or not. I was conducting a fire check to see if this was the case.

That is, when the driver is operating normally, the driver output Vc is alternately in a high level state and a low level state, as shown in FIG. 2 (C1).
Since this is input to the fire check circuit, the output of the fire φ check circuit also repeats the no-i level and low-level states in response to this, as shown in FIG. 5(d). However, at the time To shown in FIG. 2(i)
If a failure occurs in the driver, its output remains at a constant level, for example, a low level. Therefore, the processor checks the output state of this fire check circuit during the sampling period shown in FIG. 2(e), which is determined according to the dot pulse shown in FIG. If you are at the low fist level,
As shown in (f) in the figure, a fire check alarm is output at To to report the abnormality of this driver.

By the way, since the processor checks the output of the fire check circuit many times during this sampling period, the burden on the processor becomes heavy and other data processing becomes slow.

(3) Object of the Invention The object of the present invention is to improve the above-mentioned drawbacks and provide a fire check method that reduces the burden on the processor by providing a mechanism for monitoring the output of the fire arch 122 circuit. It is to be.

(4) Structure of the Invention In order to achieve this object, the fire check system of the present invention uses a fire arch 12 that monitors the operating state of the driver that drives the magnet that controls the dot matrix.
In the two circuits, a counter means for counting the operating state of the driver at each check timing, and a judgment stage I for determining whether the counted value of the counter has reached a specified value are provided, and the counter means is provided for a period of time when there is an abnormality in the driver. The feature is that an alarm is generated when

(5) Examples of the invention An embodiment of the present invention will be described with reference to FIG.

Figure 1 (a) is a configuration diagram of one embodiment of the present invention.
is a block diagram of the fire check circuit.

In the diagram, 1 is a fire check circuit, 2 is a human-powered boat,
3 is a monitoring unit, 4 is a counter, 5 is an inverter, 6 is a comparator, 7 is an OP amplifier, Mgi is a magnet, Triμ
This is a switching transistor.

The magnets Mg1ld drive the dot pins constituting the dot matrix, and the number of dot pins is equal to the number of dot pins, and each of the magnets Mgi is connected to a switching transistor Tri. When a control signal is selectively transmitted to the switching transistor Tri via the driver V, the switching transistor Tri is turned on and a drive current flows through the magnet Mgi, thereby driving the dot pin and printing a dot. At this time, the collector terminal of the switching transistor Tri has a voltage close to the ground voltage, and by detecting this terminal, the driver section consisting of the magnet Mgi and the switching transistor Tri (i = 0 to n) operates normally. It can be determined whether the

In fact, if the number of Flj dot pins is n+1, there are magnets #StMgo -Mgn, and switching transistors 'l'ro to T are connected to these magnets, respectively.
Since rn is connected, as shown in Figure 1 (b),
Each switching transistor Tro~Trn is connected to a diode l)o~ via a diode DO~Dn, Dx.
The voltage at the common portion of Dn is detected by an operational amplifier 7, and when the voltage at the input terminal of the operational amplifier is lower than the voltage at the reference terminal Eo, VL is output, and when it is higher, VH is output. When the driver section operates normally, the input voltage to the input terminal of the operational amplifier cyclically changes to the VL and VH states, as shown in FIG. 2(C).

Since the VH state corresponds to the dot pulse (b), if the output of the operational amplifier 7' is VH in the sampling period (e), it is normal, and if it is VL, it is abnormal, and the sound can be detected.

Therefore, in the present invention, as shown in FIG. 2(g), the sampling clock 5CLK corresponding to the sampling period (e) is applied to the counter 4, and at that time, the output of the fire check circuit 1, that is, the operational amplifier 7
Check whether it is outputting. Therefore, if an abnormality occurs as shown in To in Fig. 2, the output of the fire check circuit 1 is always VL as shown in Fig. 2 (d), so it is output via input port 2. The character pulse CP is transmitted to the inverter 5 and applied to the counter 4. The counter 4 counts the sampling clock 5CLK and outputs it to the comparator 6. When the character pulse CP is transmitted to the comparator 6, the The count value of the counter 4 at that time is compared with a threshold value H. This threshold value Hfl is set so as not to discriminate a state when the driver malfunctions due to noise or the like as an error, and is set to "3", for example. At this time, the count value of the counter 4 is "4" and is larger than the threshold value, so that the comparator 6 outputs a fire check φ72-person, thereby reporting an abnormal state.

Therefore, according to this, the time that the CPU'U would have sampled several times as in the past can be used for other processing.

(6) Effects of the Invention According to the present invention, the CPU fires each dot pulse.
Compared to the system that samples the signal to be checked several times, identifies abnormalities each time, and outputs a fire check alarm as shown in Figure 2 (f), a monitoring section has been installed to monitor the signal. This not only reduces the load on the CPU, but also allows a fire check to be performed accurately with a simple configuration monitoring section.

Furthermore, even if the monitoring section is implemented by the CPU, the burden can be significantly reduced compared to the conventional system.

[Brief explanation of drawings]

FIG. 1(A) is a configuration diagram of an embodiment of the present invention, FIG. 1(B) is an explanatory diagram of a fire check circuit, and FIG. 2 is an explanatory diagram of fire check operating states of the conventional and the present invention. In the diagram, 1 is a fire number check circuit, 2 is a human-powered boat,
3 is a monitoring section, 4 is a counter, 5 is an inverter, 6 is a comparator, and 7 is an operational amplifier. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Akira Yamatani

Claims (1)

[Claims] (1) In an apparatus having a fire check circuit for monitoring the operating state of a driver that drives a magnet that controls a dot matrix, a counter means that counts the operating state of the driver at a predetermined timing based on the driving timing of the driver; A fire check method in which a determination means is provided to determine whether the count value of the counter has reached a specified value, and an alarm is generated when the driver abnormality continues for a certain period of time. ′