JPS6218273A - Charge deflection type ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To enable to correct the change in the height of a printing character due to the change in temp., by providing a temp. characteristic to charge voltage charging an ink droplet. CONSTITUTION:The deflection amount of an ink droplet increases as temp. becomes high and, as a result, the height (h) of a character increases. Contrarily, a negative temp. characteristic is provided to charge voltage V to correct the temp. characteristic of the height of the character. For example, in an electric circuit, a D/A converter 14 converts the n-bit input signal from a control part 12 to an analogue current signal which is, in turn, converted to a positive voltage signal by a resistor 15 and an operational amplifier 17. This voltage signal is amplified by an operational amplifier 20 and a transistor 24 and outputted as a straight polarity voltage signal by a clamp circuit constituted of a condenser 25 and a diode 26. Now, if a resistor 22 is constituted of a temp. sensitive resistor having a proper negative temp. characteristic, a negative temp. characteristic can be provided to the gain of a circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge deflection type inkjet recording device.

In the conventional distortion charge control type inkjet recording device, the viscosity of the ink changes depending on the temperature, and therefore the height of printed characters also changes depending on the temperature. To correct this, conventionally,
For example, a method has been proposed in which the character height is detected and controlled using a sensor (Japanese Patent Laid-Open No. 57-128564), but such a method complicates the equipment and control and requires precision in manufacturing. This will cause an increase in costs.

The present invention was made in view of the above-mentioned circumstances.
Particularly, in charge deflection type inkjet recording apparatuses, this is intended to correct changes in the height of printed characters caused by changes in the kinetic energy of ink droplets due to changes in environmental temperature.

In order to achieve the above object, the present invention records by charging and deflecting ink droplets ejected from an inkjet head.
This inkjet recording apparatus is characterized in that the charging voltage used to charge the ink droplets has temperature characteristics. Hereinafter, the present invention will be explained based on examples.

FIG. 2 is a configuration diagram for explaining an example of an inkjet recording apparatus to which the present invention is applied. 5 is a nozzle, and 6 is a charging electrode.

7a and 7b are deflection electrodes, 8 is an ink droplet, and 9 is a gutter.

10 is a recording paper, 11 is a charging voltage generation circuit, 12 is a control circuit, and 13 is an ink pressure pump;
3 supplies pressurized ink to the head 4 and collects ink from the gutter 9 at the same time. The pressurized ink supplied to the head 4 is ejected from the nozzle 5 as an inkjet stream. At this time, when an AC voltage is applied from an AC power source 1 to an electrostrictive vibrator 2 bonded to a diaphragm 3 that forms a part of the side surface of the head 4, the inkjet flow is created by distributing ink at equal intervals in synchronization with the AC voltage. Separates into drops 8. A charging voltage generating circuit 1 is applied to the charging electrode 6 at the moment when the ink droplet 8 separates.
When a predetermined voltage from 1 is applied, the ink droplet 8 becomes charged in accordance with the applied voltage at that time. charged ink droplet 8
is deflected by the electric field of the deflection electrodes 7a and 7b, and the recording paper 1
Leave a record at 0. Ink droplets 8 that are not used for printing are captured and collected by a gutter 9 and reused.

Head 4. Charged electrode6. The deflection electrodes 7a, 7b and the gutter 9 are mounted on a carriage that can move horizontally with respect to the recording paper lO, and are scanned in the horizontal direction while recording a height h in the deflection direction to create a strip-shaped recording. leave. When one scan of recording is completed, the recording paper and the carriage move relative to each other by h in the deflection direction and perform the same recording operation. Such recording is repeated in sequence to complete the predetermined recording.

Therefore, in the above inkjet recording apparatus, the third
As shown in the figure, as the temperature increases, the ink viscosity decreases, so the ink pressure decreases, and therefore the velocity of the ink droplet decreases and the amount of deflection increases. Conversely, as the temperature decreases, the amount of deflection decreases. As a result, the character height h increases as the temperature increases.

On the other hand, if the charging voltage (2) is given a negative temperature characteristic as shown in FIG. 4, it becomes possible to correct the temperature characteristic of the character height.

The present invention has been made based on the above-mentioned principle, and FIG. 1 is a diagram showing an example of a charging voltage generating circuit for carrying out the above-described present invention. In Figure 1, 14 is D
/A converter, which converts the n-bit input signal from the control unit 12 into an analog current signal. This current signal is converted into a positive voltage signal by a resistor 15 and an operational amplifier 17. This voltage signal is amplified by the operational amplifier 20 and further by the transistor 24, and outputted as a positive voltage signal by a clamp circuit composed of a capacitor 25 and a diode 26. Now, in FIG. 1, if the resistor 22 is a temperature-sensitive resistor with an appropriate negative temperature characteristic, the circuit gain can have a negative temperature characteristic, and therefore, the voltage with the characteristic shown in FIG. You can get the output.

Various examples of the use of temperature-sensitive resistors can be considered. For example, a resistor 18 having positive temperature characteristics may be used, and a resistor 21 having positive temperature characteristics may be used to obtain the desired characteristics.

Background As is clear from the above description, according to the present invention, it is possible to correct changes in character height due to environmental temperature with a simple configuration, and to provide a low-cost and highly reliable inkjet recording device. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an electric circuit used in carrying out the present invention, FIG. 2 is a diagram showing an example of an inkjet recording apparatus to which the present invention is applied, and FIG. 3 is a diagram showing ink temperature and printing. FIG. 4, which is a diagram showing the relationship with character height, is a diagram showing the temperature characteristics of charging voltage. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Electrostrictive vibrator, 3... Vibration plate, 4... Inkjet head, 5... Nozzle,
6...Charged electrode. 7a, 7b... Deflection electrode, 8... Ink droplet, 9...
・Gutter. DESCRIPTION OF SYMBOLS 10...Recording paper, 11...Charging voltage generation circuit, 12
... Control circuit, 13... Ink pressure pump, 14.
...D/A converter, 20... operational amplifier.

Claims (2)

[Claims] (1) In an inkjet recording device that records by charging and deflecting ink droplets ejected from an inkjet head, the charging deflection type inkjet recording device is characterized in that the charging voltage for charging the ink droplets has temperature characteristics. . (2) The inkjet recording apparatus according to claim (1), wherein the temperature characteristic of the charging voltage has an inclination in the same direction as the temperature characteristic of the kinetic energy of the ink droplet.