JP2857423B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording apparatus.

2. Description of the Related Art A discharge port for discharging a recording liquid in a predetermined direction, a liquid path having a straight portion communicating with the discharge port, an inlet for supplying the recording liquid through the liquid path, Energy supply means for applying heat to the recording liquid in the straight portion of the liquid path to cause a state change due to the heat, and discharging the storage liquid based on the state change. A so-called bubble jet recording apparatus which forms flying droplets by discharging from an outlet to form recording droplets is known (Japanese Patent Publication No.
Further, as a method for expressing halftone (change in droplet diameter) in such a bubble jet recording apparatus, for example, a plurality of droplets are printed in accordance with density information by generating minute ink droplets with a high frequency pulse. (US Patent No. 450344)
No. 4), a method in which a predetermined number of heating elements are selected from a plurality of heating elements and the size of bubbles is changed (Japanese Patent Publication No. Sho 62-46358). One that selectively changes the size of bubbles (Japanese Patent Publication No. Sho 62-46359), one that combines a heating element and a piezoelectric element (Japanese Patent Application Laid-Open No. Sho 60-46359).
Japanese Patent Application Laid-Open No. 63-42872), in which a heating element has a thickness distribution to change the amount of bubbles by changing input energy.
However, both have the disadvantage that the drive circuit and the heating element configuration are complicated, the production yield is reduced, and the cost is increased.

Further, a part of the recording liquid supplied to a liquid path communicating with a discharge port provided for discharging the recording liquid absorbs electromagnetic wave energy absorbed by the recording liquid and generates heat, thereby generating the liquid path. A part of the recording liquid undergoes a state change due to heat therein, and based on the state change, a part of the recording liquid is discharged from the discharge port to form flying droplets, and the droplets adhere to the recording member. The inkjet recording device that records by
For example, it is known in Japanese Patent Publication No. 61-61984 and U.S. Pat. No. 3,655,379. Thus, in a recording device utilizing this electromagnetic wave energy, in order to change the heat generation state of a liquid using a practically-available semiconductor laser (low-cost, maximum 50 mW), in addition to the absorption coefficient of the light absorption layer, Although it is necessary to reduce the thickness, the above-mentioned known examples do not show these concepts, and there is no concept of halftone expression.

Further, the pressure chamber, which is in continuous communication with the orifice and the ink reservoir, is filled with ink from the ink reservoir, and the pressure chamber is
At least a part of the wall is configured to be deformed by the electromechanical conversion means, and at the time of non-recording, the ink is kept in an equilibrium state by the static pressure of the ink in the ink reservoir and the surface tension of the ink at the orifice, When the electric pulse is applied, the wall of the pressure chamber is displaced inward by the operation of the electromechanical conversion means to rapidly reduce the volume of the pressure chamber, and a part of the ink in the pressure chamber is reduced to one piece. An ink jet recording apparatus in which ink droplets are ejected from an orifice toward a recording medium, and after ejecting one ink droplet, the volume of the pressure chamber is restored to restore the initial ink equilibrium state is disclosed in, for example, It is known in JP-A-53-12138. Thus, in a pressurized on-demand ink jet recording apparatus using this piezoelectric element, halftone expression can be achieved by changing the peak value and pulse width of the drive voltage pulse, but the width of halftone recording is not necessarily limited. Was not enough.

Object The present invention has been made in view of the above-mentioned circumstances, and in particular, has a simple configuration, a good yield, and is inexpensive.
An object of the present invention is to provide an ink jet recording apparatus capable of performing halftone printing with a wide range of halftone printing.

Configuration In order to achieve the above object, the present invention provides a nozzle structure having one or more nozzles, a liquid chamber communicating with the nozzles for storing a recording liquid, and a part of a wall of the liquid chamber facing the nozzles. And an energy applying means for discharging the recording liquid from the nozzle, a means for controlling the energy applying means, and a control means for changing the distance between the nozzle structure and the energy applying means and keeping it constant. Which is characterized by having Less than,
A description will be given based on an embodiment of the present invention.

1 to 3 are configuration diagrams for explaining an embodiment of an ink jet recording apparatus according to the present invention, wherein 1 is an upper plate, 2 is a nozzle, 3 is a liquid chamber, 4 is a spacer,
5 is a recording liquid, 6 is a lower plate, 7 and 8 are insulating films, 9 is a voltage pulse source for liquid chamber deformation, 10 is a heating element, 11 is a heating element drive pulse source,
12 is a bubble, 13 is a droplet, 20 is an electrode, 21 is a light absorbing layer, 22 is a laser drive pulse source, 23 is a semiconductor laser, 24 and 25 are lenses, 26 is a laser beam, 30 is a piezoelectric element, and 31 is a piezoelectric element. Each embodiment will be described below with reference to an element driving pulse source.

In the embodiment shown in FIG. 1, the periphery of the nozzle 2 is made thinner by using, for example, anisotropic etching of Si.
It is itself processed by anisotropic etching. The lower plate 6 is arranged to face the upper plate 1 with the spacer 4 interposed therebetween to constitute the liquid chamber 3. The lower plate 6 is made of Si similarly to the upper plate 1, and the nozzle 2
The heating element 10 is provided as an energy applying means for discharging the droplet from the nozzle 2. A pulse voltage _VE is applied between the upper plate and the lower plate from the liquid chamber deforming voltage pulse source 9, and the upper and lower plates are mutually deformed to the center by the electrostatic force between the two. Heating element 10 in this state
When a pulse Vp ₁ is applied from the heating element driving pulse source 11 to the air bubble 12 as known by the so-called bubble jet principle.
By but by controlling the generated liquid chamber deformed voltage V _E for ejecting the droplets 13, on the distance between the lower plate, it is possible to variable liquid chambers gap d, the distance between the generated bubbles and the nozzle is changed . This means that the liquid amount between the bubble and the nozzle is variable, and the discharge amount of the liquid droplet can be easily changed, so that the halftone expression of the image can be realized with a simple configuration and at low cost.

In the embodiment shown in FIG. 2, a laser beam which is electromagnetic wave energy is used as the energy applying means. In order to put such a device into practical use, a low-power semiconductor laser (maximum output 50
mW). When such a semiconductor laser is used, a transparent lower plate made of glass or the like having an electrode 20 for deforming the liquid chamber inside and having a light absorbing layer 21 having an absorption spectrum at the wavelength of the semiconductor laser on the liquid chamber 3 side. The lower chamber 6 is used to focus on the light absorbing layer 21. In order to discharge droplets from the nozzle with the energy of a low-power semiconductor laser, the liquid chamber gap is several tens μm or less. Although it is necessary, it is difficult to form the liquid chamber while maintaining this gap with high accuracy. Therefore, the laser drive pulse Vp ₂
Prior to the application of the liquid chamber deformation voltage pulse _VE is applied,
The liquid chamber gap is maintained at several tens of μm. At this time, Vp ₂ is applied, and a droplet is ejected due to a state change accompanying the heat generation of the light absorbing layer 21. At this time, if both V _E and Vp ₂ voltage pulses are applied simultaneously or V _E is applied slightly later than Vp ₂ , the pressing force accompanying the deformation of the liquid chamber and the thermal state change due to heat generation are superimposed, and furthermore, the droplet discharge is Efficiency is improved. Further, it is possible to vary the liquid ejection amount as in the embodiment shown in Figure 1 by controlling the V _E.

The embodiment shown in FIG. 3 uses a piezoelectric element conventionally used in a pressurized on-demand system as an energy applying means, and drives the liquid crystal chamber deforming voltage pulse _VE and the piezoelectric element 31. pulse Vp ₃ is substantially simultaneously applied. The change in the droplet diameter of the conventional pressure-on-demand method is Vp
It was obtained by changing the peak value and pulse width of ₃ ,
The range of change is not very large. In this embodiment, Vp ₃
Variation in the ejected liquid droplet diameter by wave height and the pulse width also change in V _E increases significantly in addition to.

Advantages As is clear from the above description, according to the present invention, by changing the distance between the nozzle structure and the energy applying means, an unprecedented halftone expression can be realized.

[Brief description of the drawings]

FIG. 1 to FIG. 3 are configuration diagrams for explaining an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Upper plate, 2 ... Nozzle, 3 ... Liquid chamber, 4 ... Spacer, 5 ... Recording liquid, 6 ... Lower plate, 7, 8 ... Insulating film, 9 ...
... voltage pulse source for liquid chamber deformation, 10 ... heating element, 11 ... heating element driving pulse source, 20 ... electrode, 21 ... light absorption layer, 22 ...
Laser drive pulse source, 23 ... Semiconductor laser, 24,25 ...
Lens, 26 laser light, 30 piezoelectric element, 31 piezoelectric element drive pulse source.

Claims (1)

(57) [Claims] 1. A nozzle structure having one or more nozzles,
An ink jet recording apparatus comprising: a liquid chamber that communicates with a nozzle and stores a recording liquid; and an energy applying unit that is provided on a part of a wall of the liquid chamber facing the nozzle and discharges the storage liquid from the nozzle. An ink jet recording apparatus comprising: means for controlling the distance between the nozzle structure and the energy applying means;