JPS609758A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To make it possible to confirm the presence or absence of the jet of ink particles even if recording is being made by such an arrangement wherein electric charge is given to ink particles to be jetted out through an electrode at the time of their spouting and electrical change of ink particles caused by their flying is detected through an electrode. CONSTITUTION:Simultaneously when an ink particle 3 is formed as ink is spouted from a nozzle 1, an electric charge of which polarity is contrary to that of a DC voltage given to an electrode 9 is induced in the ink particle 3. As the charged ink particle 3 flies and approaches the electrode 9, an electric charge of which polarity is contrary to that of the electric charge of the ink particle 3 is induced in the electrode 9 and the electric charge disappears as the ink particle 3 moves away from the electrode 9. A current variation to be induced in the electrode 9 in connection with the flying of the ink particle 3 is converted into a voltage (a) by a current/voltage conversion circuit 12 through a condenser 11 and it is amplified by an amplifier 13. After its noise is removed by a lowpass filter 14, the voltage is compared with a reference voltage set in a reference voltage generator 15 in advance at a comparator 16, and if the output (b) of the low pass filter 14 is larger than the reference voltage, the comparator 16 generates an ink particle detection signal (c).

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field of the Invention The present invention relates to an inkjet recording device, and particularly an inkjet recording device equipped with an ink droplet ejection detection device to confirm whether or not ink droplets are reliably ejected from a nozzle. It relates to a recording device.

(B) Background of the Technology For example, a multi-nozzle on-demand inkjet recording device is equipped with a plurality of nozzles arranged in series or in a staggered manner, and the nozzles and the recording medium (recording paper) are arranged in a direction crossing the arrangement direction. By selectively ejecting ink particles from the plurality of nozzles while relatively moving the nozzles.

The nozzle is used to record characters, etc. on a recording medium, but since the nozzle is a tiny hole with a diameter of, for example, 50 microns, the ink may not be ejected due to clogging due to ink drying or air being mixed in. . Therefore, in order to improve its reliability, an ink droplet ejection detection device is provided to confirm whether ink is reliably ejected from each nozzle.

(C) Prior art and problems In the ink droplet ejection detection device, a pressure sensitive element such as a strain gauge is installed at the position where the ink droplets ejected from the nozzle collide. A light emitting part and a light receiving part are arranged opposite to each other across the flight path of the ink particles, and changes in the amount of light detected by the receiving part as the ink particles fly are investigated.
Or it can be sprayed from a nozzle. charge to the ink particles,
There were some methods that investigated the electrical changes that occur around the ink particles as they fly.

However, since the S/N ratio of the signal obtained by the pressure-sensitive element is low in those using a pressure-sensitive element, a high-precision signal processing circuit is required to improve accuracy.

Therefore, it has the disadvantage of being expensive.

Also, for those that use light, the ink in flight is approximately 70 mm in diameter.
Because they are micron particles, a high-precision optical system is required for the light-emitting part or the light-receiving part, and the structure is also complicated.
Like the former, it had the drawback of being expensive.

Therefore, recently, it has been considered that the most effective method is to apply an electric charge to ink particles ejected from a nozzle and examine the electrical changes that occur around them as they fly (hereinafter referred to as charge utilization method).

FIG. 1 shows the first conventional example of the charge utilization method, which is often used in single-nozzle charge amount control type inkjet recording apparatuses. In the figure, 1 is the nozzle, 2
4 is a charging electrode used to charge the ink particles 3 ejected from the nozzle 1; 4 is a charging electrode used to apply a voltage of several tens to hundreds of volts between the charging electrode 2 and the ground; 5 is a detection electrode provided around the flight path of the ink particles 3 charged by the charging electrode 2; 6 is a detection electrode 5 that is used as a charging means to apply a charge to the ink particles 3; This is a detection device that detects the induced current that occurs between the ground and the ground.

However, in order to apply this method to a multi-nozzle inkjet recording device, it is necessary to provide a charging electrode 2 and a detection electrode 5 for each two nozzles, which makes the structure complicated and expensive. there were.

Further, FIG. 2 shows a second conventional example of the charge utilization method, which is currently being proposed by the present inventors in Japanese Patent Application No. 57-231382 (filed on December 24, 1988). In the figure, the same reference numerals as in FIG. 1 indicate the same objects, and 7 is a detection electrode provided at the position where the ink particles 3 ejected from the nozzle 1 and charged by the charging electrode 2 collide, and 8 is the ink droplet 3. This is a detection device that detects the amount of charge generated on the detection electrode 7 due to collision or adhesion of particles 3. Indeed, according to this detection device, only the electrode provided opposite the nozzle can serve as both a charging electrode and a detection electrode, and the structure is extremely simple, and it can be used with a single nozzle or multiple nozzles. Also, the presence or absence of ejection of ink particles can be detected with an extremely simple configuration.

However, this detection device has the disadvantage that it is necessary to provide a charging electrode 2 and a detection electrode 7, and that it is not possible to confirm whether or not the ink particles 3 are ejected while recording.

(D) Object of the Invention An object of the present invention is to provide an ink-jet recording device that has a simple structure and is equipped with an ink particle detection device that can confirm whether or not ink particles are ejected even during recording. It's about doing.

(E) Structure of the Invention The inkjet recording device of the present invention includes an electrode provided in a position that is close to a nozzle that ejects ink particles and does not impede the flight of the ink particles ejected from the nozzle, and a charging device that applies a charge to the ink particles through the electrode during ink ejection, and a detection device that detects, via the electrode, an electrical change accompanying the flight of the ink particles ejected from the nozzle. It is.

<F) Examples of the Invention The gist of the present invention will be explained in detail below by referring to two illustrated examples. FIG. 3 shows an embodiment in which the present invention is applied to an on-demand type inkjet recording apparatus. In FIG. 1, the same reference numerals as in FIGS. An electrode is provided close to the nozzle 1 that ejects the particles 3 and at a position that does not impede the flight of the ink particles ejected from the nozzle 1; 10 is a resistor provided between the DC power source 4 and the electrode 9; 11 is an electrode provided The DC blocking capacitors 12, 13, 14, 15, and 16 constitute a detection means for detecting, via the electrode 9, electrical changes occurring in the surrounding area as the ink particles ejected from the nozzle 1 fly.
12-1 and 12-2 are resistors and amplifiers that constitute the current-voltage conversion circuit 12; 13 is an amplifier that amplifies the output of the current-voltage conversion circuit 12; 14 is a low-pass filter that removes noise from the output of the amplifier 13; 15 is a low-pass filter that removes noise from the output of the amplifier 13; A reference voltage setting section 16 that sets a reference voltage is a comparator that compares the output of the low-pass filter 14 with a reference voltage set in the reference voltage setting section 15.

That is, ink particles 3 are ejected from the nozzle 1 by applying a pulsed voltage to a piezoelectric element (not shown) to pressurize ink within a pressure chamber (not shown). When a DC voltage of 100 V is applied to the electrode 9 from the charging power source 4 through the resistor 10, the ink particles 3 become conductive, so that the ink is ejected from the nozzle 1 and the ink particles 3 are formed. On the other hand, a charge having a polarity opposite to that of the DC voltage applied to the electrode 9 is induced.

As the charged ink particles 3 fly as described above and approach the electrode 9, a charge with a polarity opposite to that of the ink particles 3 is induced in the electrode 9. Afterwards, as the ink particles 3 move away from the electrode 9, this charge is removed. disappears.

A change in electric charge, that is, a change in current, induced in the electrode 9 as the ink particles 3 fly is converted to a voltage +al by a current-voltage conversion circuit 12 via a capacitor 11, amplified by an amplifier 13, and further filtered out by noise in a low-pass filter 14. After the ink particle detection signal (C1) is removed, the comparator 16 compares the ink particle detection signal (C1) with a reference voltage set in advance in the reference voltage generator 15. This voltage is sent to the printer control circuit (not shown).

The presence or absence of clogging in the nozzle 1 is confirmed, and corresponding controls are performed.

Note that the output (&) of the current-voltage conversion circuit 12 and the output () of the low-pass filter 14 when the ink particles 3 pass through the electrode 9
The relationship between bl and the output (C) of the comparator 16 is shown in FIG.

According to the above embodiment, the electrode 9, which is provided close to the nozzle 1 and at a position that does not impede the flight of ink particles ejected from the nozzle 1, is shared by the charging means and the detection means, resulting in a simple structure. An inkjet recording device equipped with an ink particle detection device can be obtained.

Although this embodiment has been described with respect to a single nozzle, it is also applicable to a multi-nozzle case, although the S/N ratio will be somewhat worse.

(G) Detailed Description of the Invention According to the present invention, it is possible to obtain an inkjet recording device that has a simple structure and can confirm whether or not ink particles are ejected even during recording. .

[Brief explanation of the drawing]

FIG. 1 shows a first conventional example of an inkjet recording device equipped with an ink particle detection device using a charge type. FIG. 2 shows a second conventional example, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is an explanatory diagram of an embodiment of the present invention. In the figure, 1 is a nozzle, 3 is an ink particle, 4 is a charging power source, 9 is an electrode, 12 is a current-voltage conversion circuit, 13 is an amplifier, and 16 is a comparator.

Claims (1)

[Claims] An electrode is provided close to a nozzle that ejects ink particles and at a position that does not impede the flight of ink particles ejected from the nozzle, and an electrode is provided to ink particles ejected from the nozzle through the electrode when ink particles are ejected. An inkjet recording apparatus comprising: a charging device that applies a charge; and a detection device that detects, via the electrode, an electrical change accompanying the flight of ink particles ejected from the nozzle.