JPH05147228A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To make it possible to eject an ink with a proper viscosity from a nozzle in accordance with the surrounding temp. even when it is fluctuated and to keep a recording with high quality without increasing the consumed electricity in an ink jet recording apparatus wherein drops of the ink are ejected on a recording face from the nozzle by applying a pressure to the ink fed from an ink tank. CONSTITUTION:In an ink jet recording apparatus having ink tanks 1 and 21 storing ink and ink drops ejecting parts 2 and 22 wherein drops of ink are ejected from a nozzle 33 by providing an ejecting force to the ink fed from the ink tanks 1 and 21, the apparatus is constituted in such a way that at least a plurality of ink tanks 1 and 21 are provided and an ink with different viscosity is stored in each tank and the ink with different viscosity can be selectively ejected from the nozzle 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus in which pressure is applied to ink supplied from an ink tank to eject ink droplets from a nozzle onto a recording surface.

In an ink jet recording apparatus, one ink droplet ejected from a nozzle forms one dot on a recording surface, and the quality of recording greatly depends on the state of the ink droplet.

[0003]

2. Description of the Related Art The viscosity of ink ejected from a nozzle fluctuates depending on the ambient temperature, whereby the particle velocity, frequency characteristics, ejected ink amount, etc. change, and good recording cannot be obtained within the guaranteed temperature range. There are cases.

FIG. 9 shows an example of the relationship between the ink viscosity and the particle velocity under a constant driving condition of the piezoelectric element. The higher the ink viscosity, the lower the particle velocity. The particle velocity is closely related to the flight angle of the ink droplet, and if the particle velocity becomes too slow, the ink droplet will be easily bent due to the influence of disturbance, and as a result, the dot position accuracy on the recording paper will deteriorate and the recording quality will decrease. Deteriorate. Desirably the speed fluctuation is ±
It is 20% or less.

FIG. 10 shows an example of frequency characteristics of particle velocity with ink viscosity as a parameter. As shown by the solid line, when the ink viscosity is low, the velocity fluctuation range is large, which affects the dot position accuracy.

FIG. 11 shows an example of the relationship between the ink viscosity and the ink ejection amount. The higher the ink viscosity, the smaller the ejection amount, and as a result, the smaller the dot diameter on the recording paper.

Therefore, in order to reduce the dependency of the recording quality on the ink viscosity, conventionally, a heater for keeping the ink temperature constant is provided to keep the ink viscosity constant,
The drive conditions such as the piezoelectric element that applies pressure to the ink are controlled in accordance with the ambient temperature to perform uniform ink ejection in which the change in the ink viscosity is corrected.

[0008]

However, when a heater is used, power consumption becomes large, and when the temperature is low, there is a drawback that the heater cannot be used until the ink is warmed after power is turned on.

When controlling the driving conditions of the piezoelectric element, since the viscosity of the ink remains unfavorably changed, it is difficult to form an ink droplet in an ideal state, and high quality recording is performed. There are a lot of cases where you can't get lost.

Therefore, according to the present invention, even if the ambient temperature fluctuates, an ink having an appropriate viscosity is ejected from the nozzle to maintain high quality recording without increasing power consumption. An object is to provide a recording device.

[0011]

In order to achieve the above object, the ink jet recording apparatus of the present invention, as shown in FIG. 1, includes ink tanks 1 and 21 for storing ink,
In an ink jet recording apparatus having an ink droplet jetting unit 2 and 22 for jetting an ink droplet from a nozzle 33 by giving a jetting force to the ink supplied from the ink tanks 1 and 21, at least a plurality of the ink tanks 1 and 21 are provided. Ink having different viscosities is stored in each tank so that the inks having different viscosities can be selectively ejected from the nozzles 33.

Further, a temperature sensor 25 for detecting the temperature in the vicinity of the ink droplet ejecting portions 2, 22 is provided, and the ink tank 1, which supplies ink to the nozzle 33 in response to a detection signal from the temperature sensor 25. Ink tank selecting means 26 for selecting 21 may be provided.

[0013]

If the viscosity of the ink changes due to the fluctuation of the ambient temperature, the ink tanks 1 and 21 for supplying the ink to the nozzle 33 can be selected accordingly to eject the ink of the appropriate viscosity.

When the temperature sensor 25 is used,
In response to the detection signal from the temperature sensor 25, the ink tanks 1 and 21 that store ink of an appropriate viscosity are selected by the ink tank selection means 26.

[0015]

Embodiments will be described with reference to the drawings. Figure 2
The printing unit of the inkjet printer is shown, and the recording paper 100 is pressed by the bail roller 11 and wound around the platen 12. A carriage 14 is slidably attached to a stay shaft 13 provided in parallel with the platen 12, and the carriage 14 reciprocates along the surface of the recording paper 100.

On the carriage 14, an ink tank cartridge 1 that stores liquid ink, and an ink jet head that applies pressure to the ink supplied from the ink tank cartridge 1 to eject ink droplets from the nozzle toward the surface of the recording paper 100. 2 and 2 are detachably attached.

The ink tank cartridge 1 and the ink jet head 2 are integrally provided as schematically shown in FIG. 3, and a recess 16 formed in the cover of the ink jet head 2 is provided so as to project toward the carriage 14. The convex portion 17 is click-engaged. In this way, the ink tank cartridge 1 and the inkjet head 2 are detachably fixed to the carriage 14.

FIG. 4 shows the internal structure of the ink jet head 2. A stainless steel plate 3 having a plurality of sets (for example, 12 sets) of ink flow paths 31, pressure chambers 32, nozzles 33, etc. is formed by a photo-etching technique. It is also sandwiched between a substrate 4 made of a stainless steel plate and a vibration plate 5 and bonded by diffusion bonding.

Piezoelectric elements 6 that are deformed by voltage application and apply pressure to the ink in the pressure chambers 32 are bonded to the vibration plate 5 at positions corresponding to the respective pressure chambers 32.
Reference numeral 7 is a driver for applying a voltage to the piezoelectric element 6.

Returning to FIG. 2, the ink jet printer is provided with another set of the ink tank cartridge 21 and the ink jet head 22. And, in the first ink tank cartridge 1,
A high-viscosity A ink having a temperature-dependent characteristic of viscosity is stored in FIG. 5, and a low-viscosity B ink is stored in the second ink tank cartridge 21.

That is, the ink A and the ink B have different viscosity characteristics with respect to temperature, and the guaranteed temperature range is, for example, 5
If the temperature is set to 35 ° C. to 35 ° C., the viscosity of the ink A changes from 5 to 2 centipoise (cP) in that temperature range, and the viscosity becomes too large in the low temperature region, and the particle velocity and the ejection amount decrease.

On the other hand, the viscosity of ink B changes from 3 to 1 centipoise in the temperature range of 5 to 35 ° C., and the viscosity becomes too small in the high temperature region, and the velocity fluctuation range in the frequency characteristic of particle velocity becomes large. I will end up.

However, if these two types of ink are used, if the ink A is used at 20 ° C. or higher and the ink B is used at 20 ° C. or lower, the ink viscosity is 3 to 1 with respect to a temperature change of 5 to 35 ° C. The change is within the range of 0.7 and the print quality can be maintained at a high level.

Therefore, in this embodiment, whether the temperature is 20 ° C. or higher is measured by an air temperature measuring device (not shown).
It is detected whether the temperature is equal to or lower than 0 ° C., and one of the two sets of the ink tank cartridges 1 and 21 and the inkjet heads 2 and 22 is selected and attached to the carriage 14 according to the temperature at that time. By doing so, the print quality can be maintained at a high level within the guaranteed temperature range.

FIG. 6 shows a second embodiment, in which two sets of ink tank cartridges 1 and 21 and ink jet heads 2 and 22 are attached to the carriage 14,
Depending on whether the detection signal from the temperature sensor 25 attached to the carriage 14 is 20 ° C. or higher or 20 ° C. or lower, which piezoelectric element 6 (6a or 6b) of the inkjet heads 2 and 22 is to be driven is selected. It is the one.

FIG. 7 schematically shows a circuit for processing the detection signal from the temperature sensor 25 of the second embodiment. The output of the temperature sensor 25 is input to the comparator 26, and the output of the comparator 26 is changed to 2.
Compared to 0 ° C., the driver 7a of the piezoelectric element 6a of the first inkjet head 2 is driven when the detected temperature is 20 ° C. or higher, and the piezoelectric element of the second inkjet head 22 is detected when the detected temperature is 20 degrees or lower. The driver 7b of 6b is driven.

FIG. 8 shows a third embodiment, in which two ink tank cartridges 1 and 21 are connected to one ink jet head 2 and a switching valve 28 is provided in the middle thereof to communicate with the ink jet head 2. Either one of the ink tank cartridges 1 and 21 can be selected. Switching of the valve 28 is performed by changing the detection signal of the temperature sensor 25 to the comparator 2 as in the second embodiment.
6 and compares it with 20 ° C., and the comparator 26
Can be performed by the output signal from the.

[0028]

According to the ink jet recording apparatus of the present invention, if the viscosity of the ink changes due to the fluctuation of the ambient temperature,
In response to this, ink with an appropriate viscosity can be ejected from the nozzle at all times, so high-quality recording can be maintained without being affected by fluctuations in ambient temperature.
Since it does not require a heater or the like for maintaining the proper viscosity of the ink, the power consumption is small, and it is possible to immediately perform recording with the ink having the proper viscosity when the power is turned on.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a partial perspective view of the first embodiment.

FIG. 3 is a partial perspective view of the first embodiment.

FIG. 4 is a partially cutaway perspective view of the first embodiment.

FIG. 5 is a diagram showing temperature dependence characteristics of viscosities of two types of ink.

FIG. 6 is a partial perspective view of the second embodiment.

FIG. 7 is a circuit block diagram of a second embodiment.

FIG. 8 is a circuit block diagram of a third embodiment.

FIG. 9 is a diagram showing a relationship between ink viscosity and particle velocity.

FIG. 10 is a diagram showing a relationship between an ink particle generation frequency and a particle velocity.

FIG. 11 is a diagram showing the relationship between the viscosity of ink and the ejection amount.

[Explanation of symbols]

 1 Ink Tank Cartridge (Ink Tank) 2 Inkjet Head (Ink Drop Ejection Section) 21 Ink Tank Cartridge (Ink Tank) 22 Inkjet Head (Ink Drop Ejection Section) 33 Nozzles

Claims (2)

[Claims] 1. An ink tank (1, 2) storing ink.
1) and an ink droplet jetting section (2, 22) for jetting an ink droplet from a nozzle (33) by giving a jetting force to the ink supplied from the ink tank (1, 21), At least a plurality of the ink tanks (1, 21) are provided, inks having different viscosities are stored in the respective tanks, and the inks having different viscosities can be selectively ejected from the nozzles (33). Inkjet recording device. 2. A temperature sensor (25) for detecting the temperature in the vicinity of the ink droplet ejection portion (2, 22) is provided, and the nozzle (33) is responsive to a detection signal from the temperature sensor (25). ) To supply ink to the ink tank (1, 2
The ink jet recording apparatus according to claim 1, further comprising an ink tank selection unit (26) for selecting 1).