JPH01301257A - Ink jet printing head - Google Patents

Abstract

PURPOSE:To uniformize the temp. of emitted ink, by preliminarily raising the temp. of ink by the heating means provided on a head main body before introducing the ink into the head main body. CONSTITUTION:A printing head main body 1 is heated to definite temp. by the heat of a heater 15 and ink is introduced into the ink passage 3 provided in the head main body 1 from an introducing port 7. However, the ink flows in a pipe 17 from an ink recirculation device 9 through a supply passage 10 before the ink is introduced into the head main body 1 and receives heat from the heater 15 provided to the rear of the head main body 1 through the pipe 17 while flows through the straight parts 17a, 17b, 17c, 17d and bent parts 17e, 17f, 17g of the pipe 17. Thereafter, the ink flows in the head main body 1 to be emitted from the nozzles 4, 4... of the head main body 1. By this method, the temp. of the ink is uniformized over the longitudinal direction of the printing head main body 1 and printing imparting excellent image quality can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a print head used in an ink jet printer, and more particularly to an ink jet print head that performs printing by heating ink to a constant temperature.

[Prior Art] Conventionally, as the above-mentioned inkjet printer, there are the following types. As shown in FIG. 9, ink is introduced into the printer head main body 30 through an introduction hole 31, and this ink is ejected from a large number of nozzles 32, 32, etc. provided in the longitudinal direction of the printer head main body 30. do. At that time, the printer head main body 30 is vibrated by an imager (not shown) provided inside the printer head main body 30 along the longitudinal direction, and as shown in FIG.
I shoot. After the particles of ink droplets are charged by the charging electrode 34, they are deflected by the electric field of the deflection electrode 35 and fly onto recording paper (not shown) to record an image. ing. In the figure, 36 is an outflow hole for circulating ink as necessary.

By the way, in the above-mentioned inkjet printer, when the temperature of the ink ejected from the printer head main body 30 changes, the physical properties such as the viscosity of the ink change, and the shape of the ink particles and the distance at which the ink is separated as particles vary. , even if the ink droplets are charged with a predetermined charge, they may not fly to the predetermined position, or the size of the printed dots may change.
Variations occur in recorded images, and print quality deteriorates.

Therefore, in this type of inkjet printer 43, means are taken to maintain the temperature of the ink constant.

As means for keeping the temperature of the ink constant as described above, there are the following methods. That is, as shown in FIG. 10, a heater 37 is fixed to the back surface of the printer head body 30 along the longitudinal direction, and a temperature sensor 38 is provided at the center of the upper surface of the printer head body 30. Then, this temperature sensor 38 causes the printer head main body 3 to
0 temperature is detected, the power supply to the heater 37 is controlled to raise the temperature of the printer head main body 30 to a constant wetness, and the temperature of the ink supplied into this printer head main body 30 is raised to a constant wetness. It is configured.

[Problem to be Solved by the Invention 1] However, the above-mentioned prior art has the following problems. In other words, this method heats the printer head body to ambient temperature and transfers the heat of the printer head body to the ink to raise the temperature of the ink. Therefore, on the introduction hole side of the printer head body, ink flows immediately into the nozzle. Since the ink is ejected from the printer head, the temperature of the ink is not sufficiently raised by heat conduction from the printer head body, and the temperature of the ink is low. On the other hand, on the discharge hole side of the printer head main body, the temperature of the ink is sufficiently raised while it flows into the printer head main body, and the ink is ejected from the nozzles in the middle, so there is less ink flow matrix. The temperature of the ink becomes high. As shown in Figure 11, the temperature distribution of the ink in the longitudinal direction of the printer head body has a temperature gradient that is low on the inlet hole side and high on the discharge hole side, making it impossible to uniformly raise the temperature of the ink. There was a problem. Therefore, as described above, there is a problem that variations occur in the particle form of the ink and the cutting distance, resulting in a decrease in printing quality.

Therefore, as a solution to the above problems,
A method as shown in No. 2-41047 has already been proposed. This is to raise the temperature of ink and supply it into the print head body, but by providing the printer head body with temperature raising means that compensates for the internal ink temperature gradient, the ink is ejected from the printer head body. This is designed to equalize the temperature of the ink.

However, in this case, in addition to the temperature raising means for drying the ink supplied to the printer head body, it is necessary to separately provide a temperature raising means for compensating for the temperature gradient of the ink within the printer head body. , two temperature raising means are required, resulting in new problems such as high cost and increased power consumption.

[Means for Solving the Problems] Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to reduce the cost and consumption by requiring only one temperature raising means. It is an object of the present invention to provide an ink jet print head that does not cause an increase in electric power and can uniformize the temperature of ink ejected from a head main body.

That is, the present invention provides an inkjet print head in which a head body in which a plurality of nozzles are arranged in one direction is provided with a temperature raising means, and the ink introduced into the head body is heated by the temperature raising means to record an image. , the head main body is configured to be provided with a preheating channel for circulating ink and preheating the ink by heat of the temperature raising means before introducing the ink into the head main body.

The head main body includes, for example, a nozzle section having a large number of nozzles along the longitudinal direction, an ink passage that supplies ink to the nozzle section, and a vibration applied to the ink in the ink passage to cause the ink to be ejected from the nozzle. A device equipped with a vibration generating means for turning the ink into particles is used.

[Function 1] In the present invention, this preheating is achieved by providing a preheating channel in the head body, which circulates the ink and raises the temperature of the ink in advance by the heat of the temperature raising means, before introducing the ink into the head body. After the temperature of the ink is raised to a certain extent by the flow path, the ink is introduced into the head main body. By doing so, the temperature of the ink is raised to a certain extent by the heat of the temperature raising means while flowing through the preheating flow path, and then the ink is introduced into the head body and the temperature is constantly raised to approximately the same temperature as the head body. Therefore, the temperature of the ink ejected from the nozzles provided along the longitudinal direction of the head main body can be approximately equalized.

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 3 shows an inkjet printer to which the inkjet printer 1 to head according to the present invention can be applied. In the figure, reference numeral 1 denotes a pudding 1 to a head main body that generates ink droplets, and the pudding 1 to head main body 1 are formed of metal or the like into an elongated box shape. In other words,
As shown in FIG. 4, the print head main body 1 includes a thick substrate 2, in which an ink passage 3 having a tapered cross section is formed along the longitudinal direction. A large number of nozzles 4 are arranged along the longitudinal direction on the front side of the substrate 2.
．． A nozzle plate 5 having a nozzle plate 4 is fixed thereto, and a back plate 6 is fixed to the back side of the substrate 2.
The ink passage 3 is sealed against liquid (1B). Also, between the substrate 2 and the back plate 6,
A vibrator 11 such as a piezoelectric element is interposed, which applies vibration to the ink in the ink passage 3 at a predetermined period, and causes the nozzle 4 to
．． As shown in FIG. 4, the ink ejected from 4... is made into particles and is ejected as ink droplets. Furthermore, at both ends of the print head body 1,
An introduction hole 7 for introducing ink into an ink passage 3 provided inside, and a discharge hole 8 for discharging ink are provided.

As shown in FIG. 1, the print head main body 1 introduces ink from an ink circulation device 9 through an introduction hole 7 through a supply path 10, and a large number of nozzles 4 provided in the longitudinal direction.
．． Ink is ejected from 4... The ink circulation device 9 includes a pump, a filter, a solenoid valve, and the like.

The ink drops ejected from the above nozzles 4.4...
As shown in FIG. 3, after being charged with a predetermined charge by the charging electrode 12, it is deflected by the electric field created by the deflection electrode 13 and flies onto a recording sheet (not shown). Note that the discharge hole 8 is for circulating ink from the printer head main body 1 when necessary.
It is connected to the ink circulation device 9 via a circulation path 14 .

On the back side of the print head main body 1, as shown in FIG.
is fixed by adhesive or other means. This heater 1
5 is formed in a surface shape similar to the back shape of the print head main body 1 and slightly smaller than this, and by back-drying the print head main body 1, the ink flowing through the ink passage 3 provided inside is directed to a predetermined level. For example, the temperature of 30-40
This is for raising the temperature to ℃.

By the way, in this embodiment, the print head body has
Before introducing ink into the head body, a preheating channel is provided for circulating ink and preheating the ink by the heat of the 'RQ means. That is, as shown in FIGS. 1 and 4, on the back surface of the print head main body 1, there is a plate several meters in diameter made of a material with excellent thermal conductivity such as Teflon or metal such as SUS.
A vibrator 17 of m is fixed, and the preheating flow path 16 is formed by this vibrator 17.

The vibrator 17 has four linear portions 17a, 117b, 17c arranged linearly along the longitudinal direction on the surface of the back plate 6 of the print head main body 1.

17d, and these straight parts 17a, 17b, 17C117
Three curved parts 17e, 17f, 17 connecting d in series
It is equipped with 9.

As shown in FIG. 1, this vibrator 17 has a low thermal conductivity because it efficiently raises the temperature of the unheated ink flowing inside using the heat of the heater 15 provided on the back of the print head body 1. It is fixed to the back plate 6 of the print head main body 1 by means of adhesive, tape, welding, or the like. In addition, the straight part 1 of the above-mentioned vibrator
An end of the straight portion 7a is connected to the supply path 10, and an end of the straight portion 17d is connected to the introduction hole 7 of the print head body 1. Then, by flowing unheated ink into the vibrator 17, the vibrator 1
The temperature of the ink flowing through the print head body 1 is raised in advance by the heat of the heater 15 provided on the back side of the print head body 1, and then the heated ink is introduced into the print head body 1 through the introduction hole 7 to which the vibrator 17 is connected. It is set to be introduced.

In addition, in order to increase the contact area with the heater 15, the vibrator 17 has straight portions 17a, 17b, 117C, and 17d.
The curved portions 17e, 17f, and 17Q may all be molded with synthetic resin such as epoxy resin.

In the above configuration, in the inkjet print head according to this embodiment, the temperature of the ink is adjusted as follows. That is, the print head body 1 is heated to a constant temperature by the heat of the heater 15, and ink is introduced from the introduction hole 7 into the ink passage 3 provided inside the print head body 1. However, before the ink is introduced into the printhead body 1, it flows from the ink circulation device 9 through the supply path 10 into the vibrator 17.

Then, the ink is applied to the straight parts 17a and 17b of the vibrator 17.
, 17c, 17d and the curved portions 17e, 17f, 17g, heat is received from the heater 15 provided on the back of the print head body 1 via the vibrator 17, and the set temperature within the print head body 1 is reached. Although not reached, the temperature is raised to a certain level in advance. After that, the ink is transferred to the introduction hole 7.
The liquid flows into the printer head main body 1 from the printer head main body 1 and is discharged from the nozzles 4, 4, . . . of the printer head main body 1.

In this way, after the temperature of the ink is raised in advance by the heat of the heater 15 that raises the temperature of the print head body 1, the ink is introduced into the print head body 1 and placed along the longitudinal direction of the head body 1. Since the ink is ejected from the nozzles 4, 4, . The ink to be ejected is also ejected from the nozzles 4, 4, .

Therefore, as shown in FIG. 5, the temperature of the ink can be approximately equalized in the longitudinal direction of the print head body 1, and due to variations in the physical properties such as the viscosity of the ink due to differences in temperature, It is possible to prevent the print quality from deteriorating due to variations in the particle size and particle size distance, and it is possible to perform printing with uniform and excellent image quality.

6 and 7 show another embodiment of the present invention, and the same parts as in the previous embodiment are given the same reference numerals. In this embodiment, the preheating channel 16 is Vibrator 1
7, but as shown in FIG. 7, it is formed by plate-shaped members 21a and 21b having a flow path 20 having the same shape as the vibrator 17. In such a case, the contact area between the plate-like members 21a, 21b and the heater 15 increases, and heat is efficiently transferred from the heater 15 to the plate-like members 21a, 21b.
The temperature of the ink flowing in the flow path 20 provided inside the tube 21b can be efficiently raised. Since the other configurations and operations are the same as those of the previous embodiment, their explanations will be omitted.

FIG. 8 shows still another embodiment of the present invention, and the same parts as in the previous embodiment are given the same reference numerals. In this embodiment, the formation of the preheating flow path is The method is different from the previous embodiment.

That is, the back plate 6 of the print head main body 1 is formed by overlapping two plate materials 6a and 6b, as shown in FIG. A passage 22 having the same shape as the vibrator 17 shown in FIG. 1 is bored along. And this plate material 6
By joining the other plate material 6b to a in a liquid-tight manner,
A preheating channel 16 is formed inside the print head main body 1 . An outflow end 22a of the passage 22 communicates with an introduction hole 7 provided inside the print head body 1, and an inflow end 22b thereof is connected to the supply path 10.

In this way, the preheating channel 1 is directly connected to the print head body 1.
6, the ink comes into direct contact with the print head main body 1, so the heat transfer efficiency is good, the temperature of the ink can be raised efficiently, and the temperature of the ink can be made more uniform. Since the other configurations and operations are the same as those of the previous embodiment, their explanations will be omitted.

[Effects of the Invention] This invention heats up the ink in advance by a temperature raising means provided in the head body before introducing the ink into the head body, and the temperature raising means raises the temperature of the head body. Since it is only necessary to use only one head, the temperature of the ink ejected from the head body can be approximately equalized without causing an increase in cost or power consumption.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of an inkjet printer 1-head according to the present invention, Fig. 2 is a cross-sectional view showing the structure of a pipe installation, and Fig. 3 is a configuration diagram showing an inkjet printer 1-printer. , FIG. 4 is a sectional view showing the print head main body, FIG. 5 is a graph showing the temperature of ink ejected from the nozzle, FIG. 6 is a configuration diagram showing another embodiment of the present invention, and FIG. Figure 6 is a configuration diagram showing an inkjet printer.
FIG. 10 is a schematic diagram showing a conventional ink jet print head, and FIG. 11 is a graph showing the temperature of ink ejected from the ink jet print head of FIG. [Explanation of symbols] 1... Print head body 4... Nozzle 15... Heater 16... Preheating channel 17... Pipe Patent applicant Fuji Xerox Co., Ltd. Representative Patent attorney Nakamura 3 people including Tomohiroku) - Bow pu lido Sa CS - To 111 Figure 5 Nozuno Listening Direction Figure 6 Figure 7 Figure 8 Figure 2b

Claims (1)

[Claims] In an inkjet print head, a head body having a plurality of nozzles arranged in one direction is provided with a temperature raising means, and the temperature raising means heats ink introduced into the head body to record an image. An inkjet print head characterized in that a preheating flow path is provided for circulating ink and preheating the ink by the heat of the temperature raising means before introducing the ink into the head main body.