JP2654179B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus using a serial recording method.

[Related Art] An ink jet recording apparatus drives an ejection energy generating element corresponding to an ink ejection port provided on the front surface of a recording head based on recording information, and ejects ink droplets from the ink ejection port toward a recording medium. (Image formation).

Such an ink jet recording apparatus also employs a serial method in which recording is performed while performing main scanning with a recording head mounted on a carriage that reciprocates in a predetermined direction (left and right directions) with respect to a recording medium. There is a line printer system in which recording is performed using a line head having ejection ports arranged over a range corresponding to the entire width of a medium.

FIG. 7 shows a general configuration example of a serial type ink jet recording apparatus.

Here, reference numeral 5 denotes a recording head in which a group of ink ejection ports is arranged on the surface facing the recording medium, and ejection energy generating elements for applying ejection energy to ink are arranged corresponding to the respective ejection ports. As the discharge energy generating element, an element using an electromechanical converter or an electrothermal converter (discharge heater)
However, since a discharge port can be arranged in a high density, a discharge heater type is preferably used.

A guide shaft 3 is provided in front of a sheet-shaped recording medium (hereinafter, referred to as a recording sheet) 2 such as paper or film whose recording surface is regulated on a platen 1, and a carriage 4 that reciprocates along the guide shaft 3. The recording head 5 is mounted thereon.

Outside the recording range of the recording head 5 mounted on the carriage 4, the ejection failure and the like are removed by abutting the front surface of the recording head 5 (the surface on which the ink ejection ports are provided) and performing ink suction from the ink ejection ports. The discharge recovery means 6 for performing the operation is provided. The recording head 5 on the carriage 4 is supplied with ink from an ink tank 7 via a tube 8. Further, a recording signal is given to the recording head 5 from a printed circuit board 9 via a flexible cable 10.

The carriage 4 moves to one of the right and left sides in the figure via the timing belt 12 by the drive of the shift motor 11, and in the process, discharge energy is generated in accordance with a recording signal given from the printed circuit board 1 via the flexible cable 10. The elements are driven, and the recording head 5 sequentially performs recording. When the recording of one line is completed, the paper feed roller 15 is rotated by a predetermined angle via the paper feed gear 14 by the driving of the paper feed motor 13 for conveying the recording sheet 2, and the recording sheet 2 is moved in the reciprocating direction of the carriage 4. Is sent vertically to Thereafter, the carriage 4 moves in the direction opposite to the previous moving direction, and in the process, the recording is sequentially performed by the recording head 5.

[Problems to be Solved by the Invention] FIGS. 8 and 9 show the ejection state of ink droplets 16 of such an ink jet recording apparatus. FIG. 8 shows the carriage 4.
9 shows a discharge state when the carriage 4 moves from left to right in FIG. 7, and FIG. 9 shows a discharge state when the carriage 4 moves from right to left in FIG.

As shown in FIG. 8, when the tube 8 for supplying ink from the ink tank 7 to the recording head 5 is disposed on the right side of the carriage 4, the tube 8 also moves to the left as the carriage 4 moves from left to right. To the right. At this time, the ink in the tube 8 is
As shown by an arrow L in FIG. 8, the recording head 5 is pressed from the tube 8 side by inertia. For this reason,
The ink droplet 16 ejected by the recording head 5 is larger than the stationary state because the ink is fed under pressure.

On the other hand, when the carriage 4 moves from right to left as shown in FIG. 9, the tube 8 also moves from right to left. At this time, as indicated by an arrow R in the figure, the ink in the tube 8 is drawn from the recording head 5 side to the tube 8 side by inertia. For this reason, the ink droplets 16 ejected from the recording head 5 may become smaller than the stationary state, or the ejected ink droplets may be separated and become unstable.

FIG. 10 shows an ink jet recording head of a form in which ink is heated by a heating element such as an electrothermal transducer in the ink jet recording head, and ink droplets are ejected by generating bubbles, from the front side in the ink droplet ejection direction. FIG. This ink jet recording head has a laminated structure as shown in the figure.
Discharge port or liquid path 19 on silicon substrate 18 provided on
A dry film section 20 for forming the film is provided. Further, a top plate 21 made of glass or the like is provided thereon. Reference numeral 22 denotes a holder that covers the front surface of the recording head.

FIG. 11 shows a cross section of the head taken along a two-dot chain line in FIG. The ejection characteristics of the ink droplets 16 will be described with reference to this drawing. Since the recording head has the above-described laminated structure, portions of different materials are formed on the left and right sides of the ejection port or liquid path 19. Comparing the wettability of the silicon substrate 18 and the glass 21 to the ink in FIG. 11, the wettability of the glass 21 is larger, and as a result, the ink droplet 16 is ejected toward the glass 21 at the time of ejection, that is, on the left side in the drawing. Will receive.

FIGS. 12 and 13 are views showing the state of the ink droplet 16 when the carriage 4 on which the recording head 5 having the above-mentioned laminated structure is mounted is moved in the left-right direction along the guide shaft 3. FIG.

As shown in FIG. 12, the ink droplets 16 are moved while the recording head 5 having the tendency of the ejection direction being biased to the left is moved to the right.
Is ejected, the ink droplet 16 to be ejected receives a force that naturally leaves the recording head 5.

On the other hand, when the carriage 4 is moved to the left as shown in FIG.
16 receives a force on the side pushed into the recording head 5 side.

That is, as shown in these figures, in the recording head in which the ejection direction tends to be inclined, the force received by the ink droplet 16 varies depending on the moving direction of the carriage 4, and as a result, the recording head 5 driven under the same condition is ejected. The ejection state, such as the diameter of the ink droplet 16, is different.

As described above, in the inkjet recording apparatus,
When printing is performed while moving the carriage in both the left and right directions due to the pressure difference due to inertia in the tube and the wettability of the constituent materials shown on the front of the print head, etc.
There was a problem that a difference in recording density or a decrease in recording quality depending on the left-right direction occurred.

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide an ink jet recording apparatus capable of performing stable image formation regardless of the direction in which the recording head moves.

[Means for Solving the Problems] For this purpose, in the present invention, a recording head for discharging ink is reciprocated in a first direction and a second direction opposite to the direction, and ink discharge is performed in the process of the reciprocating movement. An ink jet recording apparatus that performs recording by causing the recording head to eject ink in different amounts in the first direction and the second direction, the recording being performed in the first direction and in the second direction. Control means for controlling the driving conditions of the recording head so as to equalize the amount of ink ejected from the recording head at the time of recording.

[Operation] According to the above configuration, in a device in which the amount of ink ejected from the recording head varies depending on the direction in which the recording head reciprocates, the recording is performed by ejecting ink in each reciprocation. Since the driving conditions of the recording head are controlled so that the amounts of ink ejected from the head are equal to each other, it is possible to prevent a density difference from occurring in an image or the like recorded by each reciprocating movement.

Examples Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a recording head drive control system of an ink jet recording apparatus according to a first embodiment of the present invention, and is specifically applicable to the configuration shown in FIG. In this example,
Control is performed to switch the voltage among the driving conditions for the ejection energy generating element.

Here, reference numeral 23 denotes a host computer serving as a supply source of print data and various commands, and reference numeral 25 denotes an interface circuit (IF) of the ink jet printing apparatus. Reference numeral 26 denotes a microcomputer-type CPU for controlling each unit in accordance with a processing procedure described later with reference to FIG. Reference numeral 27 denotes a RAM provided with a line buffer area for storing, for example, image data for one line related to printing (image data to be printed by one main scan of the print head) and areas for various operations. A ROM storing fixed data such as a program corresponding to a processing procedure by the CPU 26. 28 is a circuit for performing the voltage switching.

Reference numeral 29 denotes a driver for the recording head 5, the shift motor 11, and the paper feed motor 13. In the recording head 5,
DTn are heat-generating resistors constituting an electrothermal converter as discharge energy generating elements provided corresponding to the n discharge ports. Sφ1 to Sφ4 schematically show coils of the shift motor 11, and Fφ1 to Fφ4 schematically show coils of the paper feed motor 13.

 FIG. 2 shows an example of a recording processing procedure according to this embodiment.

The ink jet recording apparatus according to the present embodiment interfaces recording data 24 sent from a host computer 23 with an interface.
The data is received by the CPU 26 through the CPU 25 (step S1), and is temporarily stored in the line buffer area of the RAM 27. If there is a recording start command in the recording data 24 (step S2), or
When the data stored in M27 is full (step S
In 3), the recording is started. In this case, first, the left and right recording directions are determined (step S4). By this judgment CPU2
6 sends a command to the voltage switching circuit 28 to set the left or right recording voltage value (steps S5 and S6). afterwards,
A recording signal 30 is sent to a driver 29 for driving the recording head 5, and the recording head 5 is sequentially driven until there is no more data in the line buffer to perform recording (steps S7 and S7).
9).

As a result, when recording is performed with appropriately set voltage values during leftward and rightward recording, it is possible to eliminate a density difference, deterioration of recording quality, and the like. That is,
If the ink droplet diameter ejected during recording in both the left and right directions differs due to the pressure difference due to the inertia of the tube, the inclination of the ejection direction due to the difference in wettability of the material appearing on the front of the recording head, etc. If the voltage value for driving the heating element is switched between the directional printing and the leftward printing, and the latter is made relatively larger than the former, the ink droplet diameter and the like can be made uniform and the density difference can be reduced. FIGS. 3 and 4 are a block diagram showing a recording apparatus control system according to the second embodiment of the present invention and a flowchart showing an example of the control procedure, respectively.

In this example, in order to change the driving conditions at the time of recording in the left-right direction, the pulse width of the driving signal is changed instead of performing voltage switching, and therefore, the circuit 28 in FIG. Steps in the diagram
Steps S15 and S16 were inserted instead of S5 and S6.

That is, in the present example, after the CPU 26 determines the recording in the left or right direction, for example, a drive pulse width predetermined for the left and right directions stored in the ROM 31 is selected (step S15, S16) Recording is performed by driving the driver 29 based on the signal 30 having this pulse width.

At the time of recording in the left-right direction, as a result of recording with appropriately set pulse widths, it is possible to eliminate a density difference, a decrease in print quality, and the like.

FIG. 5 shows an example of a control procedure according to the third embodiment of the present invention. In this example, the same configuration as that of FIG. 3 is adopted, but instead of switching the pulse of the driving signal of the heating element, the driving frequency of the recording head differs between leftward recording and rightward recording. Shall be. That is, steps S25 and S26 are provided instead of steps S15 and S16 shown in FIG.

As described above, in one of the leftward printing and the rightward printing, the ejection state of the recording head is deteriorated, and the driving condition may be disadvantageous. Therefore, in this example, the ejection frequency should be reduced as the driving condition for that. Thus, stable ejection can be achieved.

In this example, after determining the right and left recording / printing directions (step S4), a predetermined recording drive frequency is set (steps S25 and S26), and recording is performed based on this (step S7). At this time, since the ejection timing changes, the signal sent to the driver for driving the shift motor 11 serving as the driving source of the carriage 4 is also changed by the CPU 26 in order to change the moving speed of the carriage 4 accordingly. I do.

As a result, during printing in the left and right directions, ejection is performed at an appropriately set frequency, so that stable ejection can be achieved in both directions. Also, if the frequencies are to be made equal during recording in both the left and right directions, both must be set to a stable frequency, and therefore the frequency is set to the lower side. In the left-right direction, a higher recording speed can be realized.

FIG. 6 is a flowchart showing an example of a control procedure according to the fourth embodiment of the present invention.

There is known a configuration in which a temperature detecting means such as a thermistor is provided at an appropriate portion of a recording head, and a pulse width table is provided in a ROM in order to change a driving pulse width depending on a temperature rising state of the recording head accompanying driving. In the conventional pulse width table, the pulse width for a certain detected temperature is fixed to one to one. In this example, the pulse width table for the detected temperature is separately set for recording in the left and right directions in the configuration of FIG.
Provided in ROM31.

In this example, after the temperature is detected by the thermistor (step S30), the left and right recording directions are determined (step S30).
4) Referring to the table corresponding to the direction, set an appropriate pulse width for the detected temperature (steps S35 and S3)
6). After the setting is completed, recording is sequentially performed (step S7).

As described above, when recording is performed in the right and left directions, driving is performed with an appropriate set pulse width according to an environmental condition such as a certain temperature state. As a result, recording is performed at the same density by stable ejection in both the left and right directions. It becomes possible.

Although the voltage switching, pulse width switching, and frequency switching described with reference to FIGS. 1 to 6 are set in advance in the left and right recording directions, the set values are fixed in advance. When fine adjustment is made, at least one of the left and right set values is configured to be variable and the adjustment is performed based on the actual print result in order to eliminate the variation or the like for each recording device. It is also possible.

Further, in the above description, any one of the driving voltage, the pulse width and the frequency is switched, but these may be appropriately combined.

[Effects of the Invention] As is apparent from the above description, according to the present invention, an apparatus in which the amount of ink ejected from the recording head varies depending on the direction of the reciprocating movement of the recording head, the ink is ejected in each reciprocating movement. When performing recording by discharging, the driving conditions of the recording head are controlled so that the amounts of ink discharged from the recording head are equal to each other, so that a density difference occurs in an image or the like recorded in each reciprocating movement. Can be prevented, and high-quality recording can be performed.

[Brief description of the drawings]

FIGS. 1 and 2 are a block diagram showing a control system of the ink jet recording apparatus according to the first embodiment of the present invention and a flowchart showing an example of the control procedure, respectively. FIGS. FIG. 5 is a block diagram illustrating a control system according to a second embodiment of the present invention, and a flowchart illustrating an example of the control procedure. FIG. 5 is a flowchart illustrating a control procedure according to a third embodiment of the present invention. FIG. 7 is a flowchart showing a control procedure according to a fourth embodiment of the present invention. FIG. 7 is a perspective view of an ink jet recording apparatus to which the present invention can be applied. FIGS. 8 and 9 show discharge by inertia of a tube in the configuration shown in FIG. FIG. 10 to FIG. 13 are explanatory diagrams of a discharge state change due to a difference in wettability of the front surface of the recording head. DESCRIPTION OF SYMBOLS 1 ... Platen, 2 ... Recording sheet, 3 ... Guide shaft, 4 ... Carriage, 5 ... Recording head, 6 ... Ink recovery means, 7 ... Ink tank, 8 ... Tube, 9 ... Print Substrate, 10 ... Flexible cable, 11 ... Shift motor, 12 ... Timing belt, 13 ... Paper feed motor, 14 ... Paper feed gear, 15 ... Paper feed roller, 16 ... Ink drop, 17 ... Substrate, 18 ... Silicon substrate, 19 ... Nozzle, 20 ... Dry film, 21 ... Glass, 22 ... Holder, 23 ... Host computer, 24 ... Print data, 25 ... Interface, 26 ... CPU , 27 ... RAM, 28 ... voltage switching circuit, 29 ... driver, 30 ... recording signal, 31 ... ROM.

Claims (8)

(57) [Claims] An ink jet recording head is reciprocated in a first direction and a second direction opposite to said direction, and ink is ejected during the reciprocating movement to perform recording. An ink jet recording apparatus in which the amount of ink ejected from the first direction and the second direction is different from each other, wherein the ink is ejected from the recording head at the time of recording in the first direction and at the time of recording in the second direction. To equalize the amount of ink
An ink jet recording apparatus comprising a control unit for controlling a driving condition of the recording head. 2. The method according to claim 1, wherein the supply of ink to the recording head is performed by the first
Is performed from one of the first direction and the second direction.
The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus differs in direction. 3. The method according to claim 1, wherein the direction of the ink ejected from the recording head is deviated to one of the first direction and the second direction. 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus differs in two directions. 4. An ink jet recording apparatus according to claim 1, wherein said recording head discharges ink by utilizing thermal energy. 5. An ink jet recording apparatus according to claim 1, wherein said control means controls a voltage value of a driving signal for driving said recording head as said driving condition. . 6. An ink jet recording apparatus according to claim 1, wherein said control means controls a pulse width of a driving signal for driving said recording head as said driving condition. . 7. The printing apparatus according to claim 1, wherein the control unit controls, as the driving conditions, a frequency of a driving signal for driving the recording head and a moving speed of the recording head. 3. The ink jet recording apparatus according to claim 1. 8. The apparatus according to claim 1, wherein said control means has means referred to for controlling said driving condition in accordance with environmental conditions in each of said first and second directions. Item 5. The inkjet recording apparatus according to any one of Items 1 to 4.