JPS62152887A - Trouble detector for recording head - Google Patents

Abstract

PURPOSE:To enable a trouble due to line breakage or the like in component elements of a recording head to be detected by a simple and inexpensive circuit, by making it possible to detecting a condition where the recording head is not driven by a driving means for the head. CONSTITUTION:When a recording element 13 of a recording head is troubled due to a line breakage or the like, no voltage is supplied to an output terminal 9 because of the line breakage or the like even when a driving signal (a) is inputted through an input terminal 6, so that an output signal (b) remains at an L level. An output signal (c) from a Schmitt trigger gate 14 also remains at an H level. Therefore, at the time of the rise of an inverted signal (d) from an inverter 15, a trouble signal (f) from an output terminal 17 of a D-type latch 16 is at an H level because the output signal (c) is at the H level. To reset a trouble output thus obtained, a reset signal (e) from a reset signal terminal 18 is brought to an H level to thereby reset the latch 16. Accordingly, since the trouble due to the line breakage in the recording head or due to defective energization immediately before the line breakage is detected, the troubled recording head can be speedily restored.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a failure detection device for a recording head used in dot matrix printers, etc., which are widely used in conjunction with office automation in recent years. be.

[Conventional technology]

FIG. 4 shows an example of a recording head drive circuit applied to a conventional dot matrix printer. In this circuit, when a recording head drive signal is input from an input terminal 1, a driving transistor 3 connects the recording head, such as a resistive element, to a pixel that is a part of the recording head connected to an output terminal 4. Element 5 is driven. Note that 2 in the figure is a resistor for current limiting.

By the way, in such a recording head, printing defects such as missing dots are often caused by a disconnection of the recording element 5 that constitutes the recording head, and it was generally thought that the cause of printing defects was a disconnection of the recording element 5. .

(Problems to be Solved by the Invention) However, in recent years, in the recording heads of inkjet printers using the dot matrix system, there are many printing defects due to drying of the ink, etc. It was not easy to determine whether the printing was defective or not. For this reason, a disconnection of the recording element 5 can only be confirmed when the recovery operation from a printing failure due to drying of ink is not recovered even after performing the recovery operation several times, which has been a major drawback.

SUMMARY OF THE INVENTION In view of the above-mentioned points, it is an object of the present invention to provide a recording head that is applied to, for example, a dot matrix printer, and is capable of detecting a failure due to a disconnection of a component of the recording head using a simple and inexpensive circuit. The object of the present invention is to provide a failure detection device.

[Means to solve problems]

In order to achieve this object, the present invention includes a print head that performs printing, a drive unit that drives the print head, and a detection unit that detects that the print head is not driven by the drive unit.

[For production]

That is, in the present invention, when the recording head is not driven by the driving means due to a disconnection of the recording head, the abnormality is detected by the detection means.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the invention.

In the figure, 6 is a drive signal input terminal for the print recording head;
Reference numeral 7 denotes a resistor for limiting the current of the drive signal input from the input terminal 6. 8 is a transistor for drive output; 9 is a recording element 1 such as a resistor element corresponding to a pixel of a print recording head;
3 is the drive output terminal to which it is connected. Voltage dividing resistors 10 and 11 are connected in series between the collector and emitter of the transistor 8 and divide the voltage appearing at the drive output terminal 9.

12 is a Zener diode that absorbs the voltage divided by the resistors IO and 11 when it exceeds a certain value.

14 is a Schmitt trigger gate, 15 is an inverter, and 16 is a D-type latch as a recording means. Reference numeral 17 denotes an output terminal to which a failure signal to that effect is sent when the recording element 13 of the print recording head becomes inoperable due to failure or disconnection, as will be described later. 18 is a reset signal terminal that supplies a reset signal to the D-type latch 16. Reference numeral 19 denotes a delay circuit that delays the drive signal supplied from the input terminal 6.

In such a configuration, first, a case where the recording element 13, which is a part of the configuration of the print recording head, is operating normally will be described with reference to FIG.

At this time, when the print recording head drive signal a is input to the input terminal 6 in FIG. 1, the drive output transistor 8 drives the recording element 13 of the print recording head. The output signal of the output terminal 9 at this time is as shown in FIG. At the same time, the drive signal a is delayed by a predetermined time by the delay circuit 19, and the inverted signal d, which is further inverted by the inverter 15, is inputted to the D-type latch 16. Further, a portion of the output signal S divided by the voltage dividing resistors 10 and 11 is processed by the Schmitt trigger gate 14 to become an output signal C, and this output signal C is inputted to the D-type latch 16.

Here, if the print recording head is operating normally, when the inversion signal d rises, the output signal C will be "L" as shown in the figure.
” level, the failure output signal f at the output terminal 17 of the D-type latch 16 becomes the “L” level. Therefore,
Since the fault output signal f remains at the "L" level, no fault output is output.

On the other hand, if the recording element 13 of the print recording head has a failure due to a disconnection or the like, the waveforms at each part will be as shown in FIG.

That is, at this time, even if the drive signal a is manually input from the input terminal 6, due to a disconnection of the recording element 13, etc., no voltage is supplied to the output terminal 9, and the output signal becomes the °L"L" level. The output signal C of the trigger gate 14 also remains at the "H" level. Therefore, when the inverted signal d from the inverter 15 rises, the output signal C is at the "H" level as shown in the figure, so the failure signal f at the output terminal 17 of the D-type latch 16 is at the "H" level. becomes. To reset the failure output obtained in this way, the reset signal e of the reset signal terminal 18 is set to “H”.
” level and reset the D-type latch 16.

Although the failure detection circuit in this embodiment is constructed from individual parts, the entire circuit may be integrated into an integrated circuit instead, and furthermore, it may be integrated together with the print recording head driver. It's okay. Further, the delay circuit may be of any type as long as it can delay the human input signal for a predetermined period of time.

〔Effect of the invention〕

As explained above, according to the present invention, a failure due to a disconnection of the recording head or failure of electricity immediately before the disconnection of the recording head is detected using a simple and inexpensive configuration, so that recovery can be achieved when the recording head fails. can be carried out in a short time and efficiently.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams showing examples of waveforms of each part, and FIG. 4 is a circuit diagram of a conventional example. 6... Input terminal, 8... Transistor, 9... Output terminal, 10, 11... Voltage dividing resistor, 12... Zener diode, 13... Recording element, 14... Schmidt Trigger gate, 15... Inverter, 16... D-type latch, 17... Output terminal, 19... Delay circuit. Fig. 1 Fig. 4 = `` 工 `` え り Ｇ Ｇ Ｇ Ｇ d - QcJ % = `` 工 `` 工 `` 工 '' 工 `` 工 '' d.
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Claims (1)

[Scope of Claims] A recording head comprising: a recording head that performs recording; a driving means for driving the recording head; and a detection means for detecting that the recording head is not driven by the driving means. failure detection device.