JPH10217465A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the retention of quality of picture without receiving any influence of the ambient temperature by a method wherein the ambient temperature is detected to set the frequency of a pulse voltage, impressed on the piezoelectric element based on the ambient temperature. SOLUTION: When a predetermined temperature, corresponding to a set driving frequency, is optimum compared with an ambient temperature, detected by the temperature sensor of various sensor units 110, printing is effected while a head discharge driving unit 105 is driving a piezoelectric element with a set driving frequency. On the other hand, when the temperature is not optimum, the driving frequency of a print head is regulated and, thereafter, the printing is effected while the driving unit 105 is driving the piezoelectric element with the regulated driving frequency. Upon impressing a pulse voltage in this case, the driving frequency is reduced in accordance with the reduction of an ambient temperature. Accordingly, ink is supplemented so as to follow the deformation of the piezoelectric element when the temperature is low and hence the viscosity of the ink is low whereby the ink droplets can be flown without generating any thinning or lacking of the dot of ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus for detecting an ambient temperature.

[0002]

2. Description of the Related Art Heretofore, there has been an ink jet printer using a piezoelectric element as a print head. In such a printer head, ink in a predetermined closed space is pressurized by distortion of a piezoelectric element driven by application of a voltage. The pressurized ink flies toward the recording sheet as ink droplets from nozzles provided in a predetermined closed space.

Various types of inks are used, and physical properties such as viscosity and surface tension are strongly related to ink flying.

[0004]

Among the physical properties of the ink, the viscosity is particularly temperature-dependent, and the ambient temperature, which is often found in the specifications of commercially available printers and is assumed to be an ambient temperature of 35.degree. When the temperature is lowered between 10 ° C., the viscosity changes 1.5 times or more. A pulse voltage is applied to the piezoelectric element according to a predetermined frequency. However, if the frequency is set at an ambient temperature assuming around 25 ° C., replenishment of the ink around the nozzle cannot be completed in a low temperature when the viscosity of the ink increases. . This causes thinning or chipping of ink dots on a recording sheet on which an image is recorded, and significantly degrades image quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an ink jet recording apparatus and method capable of maintaining image quality without being affected by ambient temperature. It is to be.

[0006]

According to a first aspect of the present invention, there is provided an ink jet recording apparatus which drives a piezoelectric element by applying a pulse voltage at a predetermined frequency, presses ink, and discharges ink from an ink discharge port. is there.

The ink jet recording apparatus includes detection means for detecting the ambient temperature, and setting means for setting a frequency based on the detection of the ambient temperature by the detection means.

According to the first aspect of the present invention, the ambient temperature is detected, and the frequency of the pulse voltage applied to the piezoelectric element that ejects ink is set based on the ambient temperature.
Thus, the frequency is set according to the change in the ambient temperature, and the image quality can be maintained without being affected by the ambient temperature.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet printer which is one of embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a schematic configuration of an ink jet printer 1 according to one embodiment of the present invention.

[0011] The ink jet printer 1 uses paper or OH.
A recording sheet 2 which is a recording medium such as a P sheet, and a printer head 3 which is an inkjet printer head
A carriage 4 for holding the printer head 3, swinging shafts 5 and 6 for reciprocating the carriage 4 in parallel with the recording surface of the recording sheet 2, and swinging shafts 5 and 6 for the carriage 4.
Drive motor 7 for reciprocating drive along
The timing belt 9 and the idle pulley 8 for changing the rotation of the carriage into a reciprocating motion of the carriage are included.

The ink jet printer 1 includes a platen 10 also serving as a guide plate for guiding the recording sheet 2 along the transport path, a paper pressing plate 11 for pressing the recording sheet 2 between the platen 10 and preventing floating. Recording sheet 2
Roller 12, spur roller 13 for discharging
Paper feed knob 14 for manually conveying recording sheet 2
And a wiping device 15 for wiping unnecessary substances such as ink adhered around the nozzle portion of the printer head 3 and a suction cap 16 for removing these unnecessary substances by suction.

The recording sheet 2 is supplied to a printer head 3 by a paper feeding device such as a manual feed or a cut sheet feeder.
And the platen 10 are sent to the opposite recording unit. At this time, the rotation amount of a paper feed roller (not shown) is controlled, and the conveyance to the recording unit is controlled.

The printer head 3 uses a piezoelectric element (PZT) as an energy source for flying ink droplets. A voltage is applied to the piezoelectric element, causing distortion. This distortion changes the volume of the channel filled with ink. Due to this change in volume, ink is ejected from nozzles provided in the channel, and recording on the recording sheet 2 is performed.

The carriage 4 performs a main scan of the recording sheet 2 in the traverse direction (a direction traversing the recording sheet 2) by the driving motor 7, the idle pulley 8, and the timing belt 9, and the printer head 3 attached to the carriage 4 has one. Record the image for the line. Each time recording of one line is completed, the recording sheet 2 is fed in the vertical direction and sub-scanned, and the next line is recorded.

The image is recorded on the recording sheet 2 in this manner, and the recording sheet 2 that has passed through the recording section is discharged by a discharge roller 12 disposed downstream of the recording sheet and a spur roller 13 pressed against the discharge roller 12. Is done.

FIGS. 2 to 4 are diagrams for explaining the configuration of the printer head 3. FIG. 2 is a plan view showing a part of the printer head 3, FIG. 3 is a sectional view taken along line III-III of FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV of FIG.

The printer head 3 has a large-diameter head section 301.
And a small diameter head section 302. The large-diameter head portion 301 and the small-diameter head portion 302 have a configuration in which a channel plate 303, a partition wall 304, a diaphragm 305, and a substrate 306 are integrally laminated. Among the plurality of dot diameter ink droplets, a large diameter ink droplet is ejected from the large diameter head portion 301, and a small diameter ink droplet is ejected from the small diameter head portion 302.

The channel plate 303 is made of metal or ceramic or the like, and has a water-repellent coating layer on the surface 320. The surface facing the partition wall 304 is finely processed by Ni electroforming or a photoresist, etc.
A plurality of ink channels 308 for accommodating ink 307 and an ink inlet 311 for connecting each ink channel 308 to an ink supply chamber 310 are formed in the small-diameter head portion 302 and the small-diameter head portion 302, respectively.

As shown in FIG. 3, the ink channels 308 of the large-diameter head portion 301 and the small-diameter head portion 302 have a long groove shape extending in the direction in which the large-diameter head portion 301 and the small-diameter head portion 302 face each other. They are formed in parallel. In addition, the ink supply chamber 310 and the ink channel 30
8 is formed symmetrically with respect to the center line 312,
It is connected to an ink tank (not shown).

A thin film is used for the partition wall 304, and is fixed between the channel plate 303 and the diaphragm 305. The partition 304 is fixed in a state where a predetermined tension is applied.

The diaphragm 305 includes a PZT 315. The processing of the diaphragm 305 is first fixed to the substrate 306 with an insulating adhesive, and then the separate grooves 3 are formed by dicer processing.
18 and 319 are formed and divided. In addition, due to this division, each ink channel 30
8, the PZT column 316 located between the adjacent PZTs 315, and the surrounding wall 317 surrounding them are separated.

In the printer head 3 configured as described above, the ink 307 is supplied to the ink supply chamber 310 from an ink tank (not shown). The ink 307 in the ink supply chamber 310 is distributed to each ink channel 308 via the ink inlet 311.

From a head ejection driving unit 105 described later, P
A predetermined voltage, which is a print signal, is applied between a common electrode provided at both ends of the ZT 315 and an individual electrode, and the PZT 3
Reference numeral 15 deforms in a direction in which the partition 304 is pushed. PZT315
Is transmitted to the partition wall 304, which pressurizes the ink 307 in the ink channel 308 and causes the nozzle 30
The ink droplet flies toward the recording sheet 2 via 9.

In the present embodiment, an ink jet printer having a large diameter nozzle and a small diameter nozzle is described, but the diameter of the nozzle may be the same. In an inkjet printer having nozzles with the same diameter,
By controlling the dot diameter, printing of an image having a gradation is performed.

FIG. 5 is a block diagram showing the configuration of the control unit of the ink jet printer 1. The control unit of the inkjet printer 1 includes a CPU 101, a RAM 102,
ROM 103, data receiving unit 104, head ejection driving unit 105, head movement driving unit 106, paper feed driving unit 107, cleaning system driving unit 108, cleaning control unit 109, and various sensor units 110 In.

The CPU 101 for controlling the whole executes a program stored in the ROM 103 by using the RAM 102 as necessary. The program includes an ejection driving unit 105, a head movement driving unit 10 based on image data read from a data receiving unit 104 connected to a host computer or the like and receiving image data to be recorded.
6. A part for controlling the paper feed drive unit 107 and the various sensor units 110 to record an image on the recording sheet 2 and, when necessary, controlling the cleaning system drive unit 108, the cleaning control unit 109, and the various sensor units 110 Printer head 3
And a part for performing cleaning.

Under the control of the CPU 101, the head ejection drive unit 105 drives the PZT 315 of the printer head 3, and the head movement drive unit 106 drives the drive motor 7 that moves the carriage 4 holding the printer head 3 in the column direction.
, And the paper feed drive unit 107 drives the paper feed roller. Further, based on the control of the CPU 101, the cleaning system driving unit 108 and the cleaning control unit 109 drive a motor or the like connected to a pump necessary for cleaning. The various sensor units 110 include a temperature sensor required when controlling the drive frequency of the PZT 315.

FIG. 6 is a block diagram of the control unit, which is particularly related to the present invention.
4 is a flowchart illustrating a procedure for controlling a driving frequency of a PZT 315 performed by a PU 101.

First, in S1, it is determined whether a predetermined temperature corresponding to the set driving frequency is appropriate by comparing with the ambient temperature detected by the temperature sensor. If the predetermined temperature corresponding to the driving frequency is appropriate (at S1,
YES), in S6, the head ejection drive unit 101 performs printing while driving the piezoelectric element (PZT315) at the set drive frequency. If the predetermined temperature corresponding to the drive frequency is not appropriate (NO in S1), the printer head is at the maintenance position (in FIG. 1, the printer head 3 is at the front of the wiping device 15 and the suction cap 16). Is determined.

If the printer head is not at the maintenance position (NO in S2), the printer head is returned to the maintenance position in S3, and if the printer head is in the maintenance position (YES in S2). The process is directly shifted to S4.

In S4, the driving frequency of the printer head is adjusted. Next, in S5, S
It is determined whether the predetermined temperature corresponding to the drive frequency adjusted in 4 is appropriate by comparing with the ambient temperature detected by the temperature sensor. If the predetermined temperature corresponding to the drive frequency is not appropriate (NO in S5), the process proceeds to S4, and if the predetermined temperature corresponding to the drive frequency is appropriate (YES in S5), In S6, the head ejection drive unit 101 performs printing while driving the piezoelectric element at the set drive frequency.

Next, the physical properties of the ink will be described, and the specific setting of the drive frequency of the printer head which is changed according to the ambient temperature will be described.

FIG. 7 is a diagram showing a change in viscosity of ink used in the ink jet printer 1 with respect to temperature.

When the temperature is lowered between a normal use temperature of 35 ° C. and 10 ° C., the viscosity changes from 1.6 CP to 2.7 CP by about 1.7 times. The composition of this ink is:
82.5% of water (hereinafter all weight%), dye 3%, diethylene glycol 10%, cyclohexanol 4%,
Surflon S-145 0.2%, BIT (benzisothiazoline) 0.3%.

FIG. 8 is a diagram showing the setting of the driving frequency with respect to the ambient temperature, and FIG. 9 is a diagram showing the waveform of the pulse voltage applied to the piezoelectric element.

As shown in FIG. 9, the pulse voltage as a print signal corresponding to one dot rises with a rise time of 3 μsec, the maximum amplitude of 20 V continues for 7 μsec, and falls with a fall time of 20 μsec. The time interval between a certain pulse voltage and the next successive pulse voltage is the reciprocal of the driving frequency.

When applying such a pulse voltage,
As shown in FIG. 8, by lowering the driving frequency with a decrease in the ambient temperature, the ink is replenished so as to follow the deformation of the piezoelectric element at a low temperature when the viscosity of the ink increases, and the dots are thinned and chipped. Ink droplets can be made to fly without causing the ink droplets.

By adjusting the driving frequency of the piezoelectric element as described above, the image quality can be maintained without being affected by the ambient temperature.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an inkjet printer 1 according to one embodiment of the present invention.

FIG. 2 is a plan view illustrating a part of the printer head 3 for explaining a configuration of the printer head 3. FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2 for explaining the configuration of the printer head 3;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3 for explaining the configuration of the printer head 3;

FIG. 5 is a block diagram illustrating a configuration of a control unit of the inkjet printer 1.

FIG. 6 is a flowchart showing a procedure for controlling the driving frequency of PZT 315 performed by CPU 101 of the control unit, which is particularly related to the present invention.

FIG. 7 is a diagram showing a change in viscosity of ink used in the inkjet recording apparatus 1 with respect to temperature.

FIG. 8 is a diagram showing setting of a driving frequency with respect to an ambient temperature.

FIG. 9 is a diagram showing a waveform of a pulse voltage applied to a piezoelectric element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet printer 3 Printer head 101 CPU 105 Head discharge drive part 110 Various sensor parts 315 PZT

Claims (1)

[Claims] 1. An ink jet recording apparatus for driving a piezoelectric element by applying a pulse voltage at a predetermined frequency to press ink and discharge ink from an ink discharge port, comprising: a detecting means for detecting an ambient temperature; Setting means for setting the frequency based on the set ambient temperature.