JPH04208469A - Ink jet device for printer - Google Patents

Abstract

PURPOSE:To prevent defective printing from occurring by providing lift means for lifting an ink tank corresponding to discharge of ink from a nozzle. CONSTITUTION:When residual quantity of ink in an ink bag 15 decreases due to printing operation, the negative pressure in the ink bag 15 rises and the ink pressure to be supplied to a nozzle 5 from the ink bag 15 decreases. At this time, the ink discharge quantity is calculated based on the frequency of a piezoelectric device, a step motor 20 is driven based on this data, its torque is transferred to each gear 18 through a drive gear 19, screw rods 17 rotate, an ink cartridge 13 moves upward, so that a difference H in height between a nozzle face 5a of the nozzle 5 and the cartridge 13 becomes smaller. Accordingly, even if the residual quantity of the ink in the ink bag 15 decreases, defective printing caused by non-discharge of the ink from the nozzle face 5a and thinning in printing density can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet device, particularly an inkjet device for printers.

[Conventional technology]

2. Description of the Related Art There is a printer equipped with an inkjet device that can use inexpensive plain paper and can output graphics and color. In this type of printer, images such as characters are formed by ejecting fine ink particles from an inkjet device toward a sheet of paper.

A conventional inkjet device mainly includes a print head having a nozzle and an ink storage section for storing ink to be supplied to the print head. The nozzle of the print head has a piezoelectric element, and uses the vibrational force of the piezoelectric element to eject ink supplied from the ink storage section to the print head.

[Problem to be solved by the invention]

In the conventional inkjet apparatus, when the amount of ink remaining in the ink storage section decreases, the negative pressure inside the ink storage section increases. That is, although the rate of decrease in the amount of ink is almost constant with respect to the amount of ink discharged, the rate of change in volume of the ink accommodating portion becomes smaller as the remaining amount of ink decreases.

As the amount of ink remaining in the ink storage section decreases, it becomes difficult to supply ink from the ink storage section to the print head. As a result, in the print head, the ink pressure applied to the nozzles decreases, causing printing defects such as low print density.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet device for a printer that is less likely to cause printing defects even when the amount of ink remaining in an ink storage portion decreases.

[Means to solve the problem]

An inkjet device for a printer according to the present invention includes a print head having a nozzle, an ink storage section for storing ink to be supplied to the print head, and an ink storage section for raising the ink storage section in accordance with the amount of ink ejected from the nozzle. It is equipped with means for lifting and lowering.

[Effect]

In the inkjet device for printers of the present invention, ink supplied from the ink storage section to the print head is ejected from the nozzle to record an image. When the amount of ink remaining in the ink storage unit decreases, the negative pressure inside the ink storage unit increases and the ink pressure to the print head decreases. However, in the present invention, the ink storage unit moves up and down in response to the amount of ink ejected from the nozzles. The ink pressure supplied to the print head is maintained as the ink pressure is increased by the means. Therefore, the print head is less likely to cause printing defects.

〔Example〕

FIG. 3 is a perspective view of a printing device l of a printer employing an embodiment of the present invention.
It mainly consists of a print head 2 and a platen roller 3.

The print head 2 mainly includes a carriage 4 and nozzles 5 fixed to the carriage 4. The carriage 4 is a plate-shaped member, and is a side plate (not shown) of the printer.
It is supported slidably in the direction of the arrow in the figure by a pair of guide stays 6.6 arranged in parallel therebetween. Guide stay 6
．． Boules 177a and 7b are arranged near both ends of the pulleys 7a and 7b, respectively, and a belt 8 is stretched between the pulleys 7a and 7b. A portion of the belt 8 is inserted through and fixed to the carriage 4. One pulley 7a is connected to a motor 9, and can be rotated clockwise and counterclockwise by driving the motor 9.

The nozzle 5 extends downward from the carriage 4, as shown in FIG. The lower end of the nozzle 5 discharges ink.
The nozzle surface 5a has an opening for the purpose of discharging. A piezoelectric element is arranged in the nozzle 5 (not shown),
This piezoelectric element vibrates when voltage is applied to it and operates as a pump. That is, the piezoelectric element forms ink pressure waves within the nozzle 5 due to vibrational force, thereby causing the nozzle 5 to
The ink supplied inside can be ejected from the nozzle surface 5a.

A tube 1 is connected to the side of the nozzle 5 via a damper 10.
1 is connected. The damper IO is a device for absorbing the pulsation of ink supplied into the nozzle 5 from the ink cartridge 12 via the tube 11, which will be described later.

The other end of the tube 11 is connected to an ink supply section 12 . The ink supply section 12 includes an ink cartridge 13 and a lifting device 14. The ink cartridge 13 includes a resin case 14 formed in the shape of a rectangular parallelepiped, and an ink bag 15 housed within the case 14. The ink bag 15 is ejected from the case 14.
Divided portion 16 for connecting the lower end of the tube 11
have. The ink bag 15 is filled with granular ink made of an aqueous dispersion containing a dyed emulsion polymer or a dispersed polymer.

The lifting device 14 has four screws 17 that stand up. Four gears 18 are fixed to the lower end of each threaded rod 17. Each threaded rod 17 has a male thread (not shown) on its outer peripheral surface, and is screwed into female threads (not shown) formed at the four corners of the ink cartridge 13. A drive gear 19 meshes with the four gears 18 . Drive gear 19 is connected to stepping motor 20 . Note that the ink cartridge 13 supported by the lifting device 14 is mounted on the nozzle surface 5a of the nozzle 5, as shown in FIG.
It is arranged at a position lower than that by a height H.

The platen roller 3 is arranged below the guide stay 6.6 and parallel to the guide stay 6.6.

A paper feed unit including a paper feed cassette is arranged on the front side of the platen roller 3 in FIG. 3 (not shown).

The paper feed section includes a registration roller (not shown), which can transport the paper P in the paper feed cassette to the platen roller 3 in accordance with the timing of a print command. Further, on the back side of the platen roller 3 in FIG. 3, a paper ejection section including a paper ejection roller is arranged (not shown).
The paper discharge section can discharge the paper P from the platen roller 3 to a paper discharge tray (not shown). Furthermore, near the end of the platen roller 3 on the motor 9 side (initial position of the carriage 4),
A capping device 21 for protecting the nozzle surface 5a of the nozzle 5 is arranged.

A printer equipped with the printing device 1 is equipped with a control section 22 as shown in FIG. The control section 22 includes a control unit 23 having an I10 port 24. The control unit 23 includes a microcomputer including a CPU, ROM, RAM, etc. The input section of the I10 port 24 is connected to an external device such as a word processor and other input sections. Further, the output section of the I10 boat 24 includes a nozzle driving device for vibrating the piezoelectric element in the nozzle 5 to eject ink from the nozzle surface 5a;
The stepping motor 20 and other output sections are connected.

Next, according to the control flowchart shown in FIG.
The operation of a printer including the printing device 1 will be explained. It is assumed that a word processor is connected to the printer as an external device.

When the operator turns on the power switch, step S1
Initial settings such as arranging the carriage 4 at the initial position are performed.

When step S1 ends, the program enters a standby state. In this state, the program determines whether a print command has been input from the word processor in step S2. The program also determines whether any other commands have been input from the word processor or operator in step S6.

When a print command is input from the word processor, the program moves from step S2 to step S3.

In step S3, a print operation is performed based on a print command from the word processor. Here, the paper P is first supplied to the platen roller 3 from a paper feed section (not shown). In this state, the motor 9 drives the belt 8 based on the print command, and the carriage 4 is pulled by the belt 8 and reciprocates on the guide stay 6.6.

Further, in the nozzle 5, the piezoelectric element is vibrated by the nozzle driving device, and the ink cartridge 13 is moved through the tube 11.
The ink stored in the ink bag 15 is sucked. The ink supplied into the nozzle 5 is ejected from the nozzle surface 5a toward the paper P in response to a print command. As a result, images such as characters are recorded on the paper P based on the print command.

When the above-described printing operation is performed, the ink bag 15
Since the amount of ink remaining in the ink bag 15 decreases, the negative pressure in the ink bag 15 increases. As a result, the pressure of ink supplied from the ink bag 15 to the nozzle 5 decreases.

Next, in step S4, the amount of ink ejected from the nozzle 5 in step S3 is calculated. Here, the amount of ink ejected is calculated based on the number of vibrations of the piezoelectric element in step S3.

Next, in step S5, the stepping motor 20 is driven based on the data obtained in step S4. Here, the rotational force of the stepping motor 20 is applied to the drive gear 1.
9 to each gear 18. As a result, the threaded rod 17 rotates, the ink cartridge 13 moves upward in FIG. 1, and the height difference H between the nozzle surface 5a of the nozzle 5 and the ink cartridge 13 becomes smaller. As a result, even if the negative pressure inside the ink bag 15 increases, the pressure of the ink supplied to the nozzle 5 is maintained. Therefore, in this example,
Even if the amount of ink remaining in the ink bag 15 decreases, the nozzle surface 5
Printing defects such as no ink being ejected from a or a low print density are less likely to occur. Note that upon completion of step S5, the program returns to the standby state.

When a command other than a print command is input, such as a blank feed command for paper P, the program proceeds from step S6 to step S7.
to move to. In step S7, operations are performed based on other commands input to the printer. Step S7
When finished, the program returns to the standby state.

〔Effect of the invention〕

The inkjet device for printers of the present invention includes a lifting device for lifting the ink storage portion in accordance with the amount of ink ejected from the nozzle. Therefore, according to the present invention, it is possible to realize an inkjet device for a printer that is unlikely to cause printing defects even when the amount of ink remaining in the ink storage portion decreases.

[Brief explanation of the drawing]

FIG. 1 is a perspective schematic diagram of an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional partial view of the embodiment, FIG. 3 is a perspective view of a printing device employing the embodiment, and FIG. 4 is a perspective view of the embodiment. FIG. 5 is a schematic configuration diagram of a control section of a printer equipped with a printing device, and is a control flowchart of the printer. 2... Print head, 5... Nozzle, 13... Ink cartridge, 14... Lifting device, 20... Stepping motor. Patent applicant Yukio Ono, agent of Mita Kogyo Co., Ltd., patent attorney

Claims (1)

[Claims] (1) A print head having a nozzle, an ink storage section for storing ink to be supplied to the print head, and an elevation for raising the ink storage section in accordance with the amount of ink ejected from the nozzle. An inkjet device for a printer, comprising means and.