JPH0428558A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To prevent, with mutual interference decreased, deterioration of recording accuracy caused by viscosity increase of recording liquid by a method wherein heating means are provided in positions near a vibrating plate and pressure chambers, and the vibrating plate is made of elastic material wherein the Young' s modulus greatly decreases as the temperature rises. CONSTITUTION:Heaters 61, 62...6n provided to an upper plate 4 consisting of a silicon substrate are arranged near places facing a vibrating plate 5, and are positioned with each of pressure chambers 41, 42...4n placed in between so that they are insulated through oxide films. The heaters 61, 62...6n are heated and controlled with a temperature controlling device so that the temperature of each of the heaters is kept constant. The vibrating plate 5 is desirable to be in such characteristic that is made of such elastic material wherein the Young's modulus decreases greatly as the temperature rises. In the case where the vibrating plate is made of resin in low melting point and control range of the temperature is set between 40 deg.C and 60 deg.C, the Young's modulus becomes small being in a range having no mutual interference when the device is put in operation with the transition temperature selected at 40 deg.C and below.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus, more specifically, a pressure-controlled inkjet recording apparatus, in which a recording liquid is ejected from each pressurizing chamber by being pressurized. The present invention relates to an inkjet recording apparatus that heats a diaphragm to reduce the Young's modulus of the diaphragm to reduce mutual interference between pressurizing chambers.

A pressure-controlled inkjet recording device compresses a pressurized chamber containing recording liquid by using the strain change that occurs when voltage is applied to a piezoelectric element, and this compression causes the recording liquid to be ejected. This recording device does not require a deflection device to deflect the flying direction of ink droplets, so it is compact, and the amount of recording liquid ejected can be controlled by the voltage applied to the piezoelectric element, making it possible to express gradation. It also has features such as making it possible to

Figure 2 is a configuration diagram for explaining the conventional drive principle.
In the figure, reference numeral 1 denotes a support frame made of a rigid member that houses the main parts of the recording apparatus, and a piezoelectric body 2 containing a piezoelectric element at least in part is housed within the support frame 1. Piezoelectric body 2
has a plurality of grooves 21 in the direction perpendicular to the plane of the drawing, and is divided into a plurality of piezoelectric bodies (pressure elements) 21.2□, . . . 2n. 3 is a common electrode of the piezoelectric body 2 -3he Lt...3n
is the electrode of each of the pressure elements 2it2zt...2n divided into a plurality of parts.
□,...2n are selected electrodes 2□, 2 of the pressurizing element
By applying a voltage between □, . . . 2n and the common electrode 3, the pressure elements 21, 2 . ,...2n and the pressurized chambers 41.4. ,...with an upper plate having 4n.

It is made of silicon semiconductor etc. Each pressurized chamber 4□.

48, . . . , 4n are each pressurized by a pressurizing element to which a drive voltage is applied based on a drive command, and at this time, the recording liquid contained in the pressurizing chamber is communicated with each pressurizing chamber.

The ink is ejected from an unillustrated ejection port arranged parallel to the paper surface to record. Here, the actual radius B of the groove 21 is several tens of μm.
The piezoelectric width C of the piezoelectric body serving as the pressure element is also slightly larger than the groove width B. Reference numeral 5 denotes a diaphragm, and this diaphragm 5 has the role of a liquid seal between the pressurizing chamber and the pressurizing element, and during pressurization, the pressurizing chamber is compressed via this diaphragm 5. However, since the width B of the groove 21 and @C of the pressure element are small as described above, the elastic strain of the diaphragm 5 affects the adjacent pressure chamber, causing a change in the amount of recording liquid ejected or causing liquid dripping. So-called mutual interference occurs. In order to reduce mutual interference, the thickness of the diaphragm 5 can be made thinner or the Young's modulus can be made smaller, but if the outside temperature drops,
Normally, the Young's modulus of materials with a small Young's modulus increases as the temperature decreases, and the viscosity of the recording liquid also increases, resulting in problems such as an inability to increase the printing speed and a decrease in the clarity of the print.

In addition, the present invention has been made in part in view of the above-mentioned problems.
A heating means is arranged in a position close to the diaphragm and the pressurizing chamber,
The purpose is to reduce mutual interference by controlling the temperature of the diaphragm and the temperature of the recording liquid so that they are always within a predetermined range, and to prevent a decrease in recording accuracy due to an increase in the viscosity of the recording liquid. .

In order to achieve the above object, the present invention provides a driving section which is divided by a plurality of grooves and at least a portion between the grooves is made of a piezoelectric material, and a driving section disposed opposite to the driving section. and a diaphragm disposed between the driving section and the upper plate, the upper plate having a pressurizing chamber that causes a volume change due to the displacement of the pressurizing element, and a diaphragm disposed between the driving section and the upper plate, A recording device that records by ejecting recording liquid from an ejection port communicating with the pressurizing chamber includes a heating means in a position close to the diaphragm and the pressurizing chamber, and the diaphragm is heated as the temperature rises. The present invention is characterized in that it is made of an elastic material whose Young's modulus is greatly reduced, and that the diaphragm is made of a low-melting point resin. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a block diagram for explaining one embodiment of an inkjet recording apparatus of the present invention. In the figure, the same components as those in FIG. 2 are designated by the same reference numerals. The explanation will be omitted.

In the figure, the piezoelectric body 20 shows a laminated type in which a plurality of electrodes 30 are arranged, but this is due to the piezoelectric constant d a in the thickness direction.
If s is the same, the applied voltage can be reduced in inverse proportion to the number of laminated layers in order to obtain the same piezoelectric strain, and this simply shows that a drive device suitable for low voltage drive can be obtained to compress the pressurized chamber. There is no change in the action, and the pressurized chambers 41, 4□,...
- Although the shape of 4n is different between FIG. 1 and FIG. 2, the present invention does not care about the shape, so the same reference numerals are used. 61, 6□, . . . 6n are heaters formed on the upper plate 4 made of, for example, a silicon substrate, and are placed in the vicinity of the diaphragm 5, sandwiching the pressure chambers 41, 4 □, . It is insulated through the Each heater 61
．． 6□, . . . 6n are heated and controlled to a constant temperature by a temperature control device W (not shown). The control temperature is determined by taking into account the rise time of the temperature, the temperature dependence of each characteristic of the piezoelectric body 20, the operating temperature of the recording liquid, etc.

It is desirable to control the temperature to about 40 to 60 degrees Celsius, which is slightly higher than the environmental temperature.In actual use, high responsiveness is required as a temperature characteristic, so the heaters 61, 6
The positions of □, . . . 6n are placed in the vicinity facing the diaphragm 5, and the pressurized chambers 41, 4 □, . There is no need to limit the installation position; the important thing is that the Young's modulus of the diaphragm is maintained at a small value, mutual interference does not occur, and the viscosity of the recording liquid is used at an optimal design value. As for the characteristics of the diaphragm 5, it is preferable to use an elastic material whose Young's modulus decreases at a high rate of change as the temperature rises from the viewpoint of the ridges. For example, a resin with a low melting point behaves like a rubber above the transposition temperature and has a low Young's modulus, and below the transposition temperature it exhibits resin properties and has a large Young's modulus, so it is relatively easy to lower the transposition temperature. Can be controlled. Therefore, if the diaphragm is made of a resin with a low melting point, the control temperature on the ridges should be set at 40 to 6
When set to 0℃, if the dislocation temperature is chosen to be 40”C or less,
During use, the Young's modulus is small and can be within a Young's modulus range free of mutual interference.

As is clear from the above description, according to the present invention, the Young's modulus of the diaphragm can be reduced by disposing a heating means in the vicinity of the pressurizing chamber and the diaphragm and controlling the temperature to a predetermined temperature. It is possible to maintain the same value and record without mutual interference, and the temperature of the recording liquid can be set to the optimum temperature based on the designed value without reducing the recording speed, resulting in clear printing. Furthermore, by using a low melting point resin for the diaphragm, a low Young's modulus that does not cause mutual interference at controlled temperatures can be obtained, and since it can be handled as a resin during assembly, workability is greatly improved.

Compared to rubber, it has the advantage of being more versatile in joining methods.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an inkjet recording apparatus of the present invention,
FIG. 2 is a block diagram of a conventional inkjet recording apparatus. 1... Support frame, 2, 20... Piezoelectric body, 2. , 2□
,...2n...pressure element, 3,30...electrode, 4
...Top plate, 41°47. ...4n...pressure chamber, 5
...Vibration plate, 61, 6□, ...6n...Heater.

Claims (1)

[Claims] 1. A driving part divided by a plurality of grooves, at least a part of which is made of a piezoelectric material between the grooves, and a pressurizing chamber disposed opposite to the driving part and causing a volume change by displacement of the pressurizing element. and a diaphragm disposed between the drive unit and the upper plate, and the recording liquid is ejected from an ejection port communicating with the pressurization chamber due to a change in the volume of the pressurization chamber. An inkjet recording apparatus for recording, characterized in that the diaphragm has a heating means at a position near the diaphragm and the pressurizing chamber, and the diaphragm is made of an elastic material whose Young's modulus decreases significantly as the temperature rises. Device.