JP3222630B2 - Ink jet recording device - Google Patents

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 for performing recording by discharging ink onto a recording medium.
More specifically, the present invention relates to ejection timing control.

[0002]

2. Description of the Related Art There are two main types of discharge timing control in a print head of a conventional ink jet printing apparatus: simultaneous drive for all discharge ports and time-division drive for several discharge ports.

Here, time-division driving refers to, for example, in the case of a recording head having 64 ejection ports, the number of ejection ports is 8
Each ejection port is divided into eight blocks, and each block is sequentially driven at intervals of 20 μsec. This makes it possible to reduce the peak current for discharge as compared with the case where the discharge heaters of all the discharge ports are simultaneously driven.

When the recording head and the driving system are used in a printer (recording apparatus) of a serial scan system, for example, if the scanning speed is 200 mm / sec,

[0005]

[Equation 1] 0.2 [m / sec] × 20 × 10 ⁻⁶ [sec] = 4 ×
Since 10 ⁻⁶ [m] = 4 [μm], the ink dots recorded by each block are shifted by 4 μm in the scanning direction. In this case, since a series of recording results (ink dots) by ejection from each block has a slope, a configuration for correcting this has conventionally been proposed. The simplest correction method is to tilt the recording head (see FIGS. 6, 7, and 8).

[0006]

By the way, various measures have been taken to improve the gradation of a recorded image as one of the measures against the recent demand for higher image quality of a printer output image. As one of them, a single recording head is provided with ejection ports having different opening areas, and thereby, the sizes of ejected ink droplets (hereinafter, referred to as ejection amount) are different, and are formed on a recording medium. There has been proposed a type in which various densities can be expressed by changing the size of ink dots.

However, when such a recording head is used, the ejection speed of the ink ejected from the ejection port having a small ejection amount (the opening area is small) is equal to that of the ejection port having the large ink ejection amount (the opening area is large). Is faster than the ejection speed from the recording medium, and a difference occurs in the time to reach a recording medium such as a recording sheet. In this case, in the method of printing while moving the print head (serial scan method), there is a problem in that the landing positions of ink are shifted, and as a result, the image quality is deteriorated (see FIG. 9).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to perform serial scan type printing using a printing head having a plurality of ejection ports having different opening areas. In such a case, it is an object of the present invention to provide an ink jet printing apparatus capable of correcting a landing position shift caused by a difference in ejection amount by appropriately performing time-division driving, and performing printing with good image quality.

[0009]

According to the present invention, there is provided:
Using a recording head having a plurality of different discharge ports opening area, floor by ejecting ink onto a recording medium from said recording head
An ink jet recording apparatus that performs tone recording, wherein the scanning unit scans the recording head relative to the recording medium, and the plurality of recording heads are scanned during scanning of the recording head by the scanning unit. A time-division driving unit that divides the discharge port into a plurality of blocks, and sequentially discharges each block; and, in the sequential discharge, a discharge port block having a larger opening area and a discharge port block having a smaller opening area. A drive in which a discharge interval until discharge is longer than a discharge interval between the plurality of blocks of the discharge port having the larger opening area, and a discharge interval between the plurality of blocks of the discharge port having the same opening area is equal to each other. Timing control means, and when printing a dark portion of the print image, printing is performed using the block of the ejection port having the larger opening area. There, when recording low light unit density than the dark portion of the recorded image and performing recording by using the blocks of smaller discharge port of the opening area.

More specifically, as shown in FIG. 10A, in order to correct the inclination of the printing result by the above-described time division driving, even if the ejection port array is inclined, as shown in FIG. The landing position shifts as the ink gets closer from the ejection opening having the opening area, and the result is shown in FIG. 10B. On the other hand, a recording result as shown in FIG. 10C can be obtained by correcting the landing position shift according to the difference in the opening area of the ejection port according to the present invention.

As a configuration for this, as shown in FIG. 11, a predetermined delay time (for example, 41.7 μm) is required between the discharge of the large-diameter discharge port block and the discharge of the small-diameter discharge port block.
Seconds).

However, when the present invention is applied to time-division driving in which the ejection diameter of the recording head is smaller, the timing correction as shown in FIG. 12 is required.
In this case, since the driving pulses of the third and fourth blocks overlap the driving pulses of the fifth and sixth blocks and do not have the meaning of time-division driving, it is preferable that the driving order is performed from the ejection port having the larger diameter.

[0013]

According to the above arrangement, the discharge interval from the discharge of the block of the discharge port having the larger opening area to the discharge of the block of the discharge port having the smaller opening area is set to the plurality of discharge ports having the larger opening area. Since the discharge interval between the blocks is longer than the discharge interval between the blocks, and the opening area is equal to the discharge interval between the plurality of blocks of the same discharge port, the discharge speed and the discharge rate of the ink discharged from the discharge port having the larger opening area are increased. In accordance with the difference between the ejection speed of the ink ejected from the ejection port having the smaller area and the ejection interval between the blocks of the ejection port, it is possible to adjust the displacement of the landing position due to the ejection speed difference in the time division drive. In addition, the discharge is performed at the same discharge interval between each of the plurality of blocks having the same discharge port area. The recording of the dark part and a light part can be carried out in the absence landing position shift.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a schematic perspective view of a recording head according to an embodiment of the present invention.

This recording head has, at the top, 32 thick-area recording orifices (about 30 μm in diameter) with a large opening area, and light-area recording orifices 3 with a small opening area (about 15 μm in diameter).
Two of them are arranged in a straight line at the bottom, and in these 64 outlets, one block composed of eight continuous outlets is simultaneously discharged, and eight blocks are sequentially arranged at predetermined intervals for each block. Discharged. FIG. 4 shows a connection diagram of discharge heaters in each discharge port, and discharge is performed from each discharge port by driving these discharge heaters for each block.

An ink jet recording apparatus which performs recording by the serial scan method using the recording head shown in FIG. 3 is the same as a known apparatus except for the ejection timing control described later, and the description thereof is omitted here. In such an ink jet recording apparatus, as shown in FIG. 5, the recording head is moved (scanned) in a direction perpendicular to the paper feed direction of the recording paper, and ink is ejected from the recording head in accordance with this movement to perform recording. Do. Here, in the first scan, ejection based on the print data is performed from the 32 light-portion recording ejection openings at the bottom of the recording head, and thereafter, the recording sheet is conveyed by a distance corresponding to the 32 ejection openings. In two scans, ejection is performed from the thirty-two dark area recording ejection ports on the recording head, and an image having a width of 32 ejection ports is recorded in two scans.

Of course, in the above description, when the discharge is being performed from the discharge port for the dark portion, the discharge port for the light portion in the lower portion performs the discharge for the next row.

FIGS. 1 and 2 are views for explaining the ejection timing control according to the first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of the above control, and FIG. 2 is a timing chart of signals of respective parts shown in FIG.

In FIG. 1, reference numeral 1 denotes a pulse signal generating circuit which oscillates at 4 KHz in response to a recording start trigger signal from a control microcomputer (hereinafter abbreviated as CPU; not shown), and a signal shown in FIG. A is output.
Reference numeral 2 denotes a pulse signal A output from the generation circuit 1
The time set by U (1 in the timing chart of FIG. 2)
FIG. 2 shows a pulse signal delay circuit which delays by 21.7 μs), and outputs a signal B shown in FIG. further,
Reference numeral 3 denotes a generation circuit 1, a delay circuit 2, and a 10-MHz clock oscillation circuit that outputs a clock serving as a reference for a set time in each block described below. Reference numerals 4 and 5 denote trigger pulse signal generation circuits which receive one pulse signal from the generation circuit 1 and the delay circuit 2 and output four pulses each having a pulse width of 1 μsec at an interval of 20 μsec. , And signals C and D shown in FIG. Based on the signals C and D, signals (segment signals) Seg0 to Seg7 for selectively driving one of the eight blocks of the recording head are output from the segment signal generation circuits 6 and 7, respectively. The segment signals Seg0 to Seg3 correspond to the signal C, and are signals for driving the ejection heater in the dark portion of the recording head.
〜Seg7 correspond to the signal D and are connected in the printhead section as signals for driving the discharge heater in the light portion of the printhead.

As described above, as shown in FIG. 9, the difference between the time when the ejected ink reaches the recording medium between the large-diameter ejection port block and the small-diameter ejection port block.
1.7 μs can be eliminated by providing a delay time of 41.7 μs between the end of the group of pulses of the signal C and the beginning of the group of pulses of the signal D, and the landing position due to the difference in the arrival time of the ejected ink is reduced. The displacement can be eliminated.

Each segment signal outputs one pulse of about 15 .mu.sec from the falling edges of signals C and D.
At this time, data from the image memory 8 (hereinafter abbreviated as RAM) latched from the data latch circuit 9 by the rising edge signals (signal E in FIG. 2) of the signals C and D are output to the data lines of the recording head. . After the latch is completed, the output of the read address counter circuit 10 of the RAM 8 is incremented by 1 with the falling edge signals of the signals C and D (the signal F of FIG. 2) to prepare the data of the next block (FIG. 2). A15 to A0). R
The address of AM8 is counted up from 0000H to 5CFFH during the recording of one line (one scan) (when recording 2,976 dots in the scanning direction: 29).
76 * 8 = 23808 = 5D00H), address is 5D
The moment the address reaches 00H (set value of the register 11), the output of the comparator 12 stops the operation of the 4 KHz pulse signal generation circuit.

The operation of the circuit shown in FIG. 1 when one line of data is recorded has been described above. Before the start of recording of the next line, the CPU sets the read address of the RAM to 0000H and the CPU issues a clear signal. Is output and the above sequence is started again.

At the start of recording of one line, the CPU outputs a start signal. The output of the T flip-flop circuit 13, which toggles each time the signal is received, is connected to the highest address A15 of the RAM 8. As a result, at the time of recording the odd-numbered line, A15 becomes "1",
The address of RAM 8 is changed from 8000H to DCFFH, and A15 is set to "0" at the time of recording the even-numbered line.
H is changed to 5CFFH. The image data in RAM is
As shown in FIG. 16, the CPU rearranges and writes the data transmitted via the interface.

(Embodiment 2) In Embodiment 1 described above, an attempt was made to correct the landing position deviation by controlling the drive timing between blocks having different discharge apertures.
As shown in FIG. 3, it is also possible to insert a timing control circuit into all the discharge ports.

That is, in FIG. 13, reference numeral 201 denotes an oscillation circuit of 10 MHz which is a basic clock of this circuit, and reference numeral 202 denotes a pulse which starts oscillation at 4 KHz in response to a recording start trigger signal from the CPU. 14 shows a signal generation circuit, and this circuit 202 outputs a signal A shown in FIG. Reference numeral 203 denotes a short pulse B shown in FIG. 14 upon receiving signals from the oscillation circuit 201 and the generation circuit 202.
, And a data latch signal generating circuit 204 generates the data latch signals C0 to C7 shown in FIG. 14 one after another in response to the rising edge of the pulse. Further, reference numeral 205 denotes a read address counter of the RAM 206 which counts up in response to the falling edge of the pulse from the generation circuit 203. Before the signals C0 to C7 are output, the address of the RAM 206 is rewritten and the data bus This is for sequentially outputting data to the upper part. These output data are stored in data latch circuits 207-21.
4 latches corresponding to the ejection openings of the recording head. Further, upon receiving signals from the generation circuits 202 and 203, the enable signal generation circuit 215 determines the timing of discharging from the 64 discharge ports (set by the CPU in advance, based on the discharge heater driving signal A for each discharge port). The signals E0 to E63 shown in FIG. 14 are output with the delay time of (1) and the time for applying the voltage to the discharge heater.

As shown in FIG. 15, the discharge heater of the recording head corresponding to the circuit having this configuration requires one voltage application terminal and 64 data terminals. (See FIG. 4)
Although the circuit scale becomes large, on the other hand, fine timing correction and adjustment of the heater application time between the respective discharge ports are possible, so that a higher quality output can be obtained.

Also in this example, the landing position deviation can be corrected by providing a predetermined delay time between the block of the large-diameter discharge port and the block of the small-diameter discharge port by the output of the enable signal generation circuit 215. it can.

The time division driving to which the present invention is applied is as follows.
The present invention is not limited to one in which a plurality of continuous discharge ports are formed as one block, and can also be applied to time division driving in which discharge ports are dispersed to form one block.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body and the ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add a recording head ejection recovery means, a preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

Regarding the type and number of recording heads to be mounted, for example, only one recording head is provided corresponding to a single color ink, and a plurality of inks having different recording colors and densities are provided. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not only used as an image output terminal of an information processing apparatus such as a computer, but also for a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may take a form.

[0038]

As described above, according to the present invention,
A discharge interval from discharge of a block of a discharge port having a larger opening area to discharge of a block of a discharge port having a smaller opening area is made longer than a discharge interval between a plurality of blocks of a discharge port having a larger opening area, Since the opening area equalizes the discharge interval between each of the plurality of blocks of the same discharge port, the discharge speed of ink discharged from the discharge port having the larger opening area and the discharge rate of the ink discharged from the discharge port having the smaller opening area are all reduced. The ejection interval between the blocks of the ejection ports can be adjusted according to the difference between the ejection speed of the ink and the ejection position. The discharge is performed at the same discharge interval between each of the plurality of blocks of the outlet area, and the recording of the dark part and the light part is respectively landed. It can be carried out in the absence deviation of location.

As a result, a high-quality image can be output.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording head drive circuit according to a first embodiment of the present invention.

FIG. 2 is a timing chart of each signal in the circuit.

FIG. 3 is a schematic perspective view showing an ejection port arrangement of the recording head according to the embodiment.

FIG. 4 is a schematic diagram showing connection of a discharge heater of the recording head.

FIG. 5 is an explanatory diagram for explaining recording using the recording head.

FIG. 6 is an explanatory diagram showing a discharge port arrangement of a conventional print head and a print result.

FIG. 7 is a timing chart showing a conventional ejection timing.

FIG. 8 is an explanatory diagram for explaining correction of the inclination of a recording result by time division driving.

FIG. 9 is an explanatory diagram for explaining the occurrence of displacement of the landing position of the ejected ink from each of the large-diameter ejection port and the small-diameter ejection port.

FIGS. 10A to 10C are explanatory diagrams illustrating the correction of the landing position deviation according to the present invention.

FIG. 11 is a timing chart of the ejection control for correcting the displacement.

FIG. 12 is a timing chart showing correction according to the present invention when discharging from a small-diameter discharge port.

FIG. 13 is a block diagram of a recording head drive circuit according to a second embodiment of the present invention.

14 is a timing chart of each signal shown in FIG.

FIG. 15 is a schematic diagram showing connections of discharge heaters of a print head used in the second embodiment.

FIG. 16 is a schematic diagram showing a memory map of image data stored in an image memory in the first embodiment.

[Explanation of symbols]

 1,202 4 KHz pulse signal generation circuit 2 Pulse signal delay circuit 3,201 10 KHz oscillation circuit 4,5 Trigger pulse signal generation circuit 6,7 Segment signal generation circuit 8,206 RAM 9,207-214 Data latch circuit 10,205 Read Address counter 13 Flip-flop 203 Data trigger signal generation circuit 204 Data latch signal generation circuit 215 Enable signal generation circuit

Claims (2)

(57) [Claims] An ink jet recording apparatus which uses a recording head having a plurality of discharge ports having different opening areas and discharges ink from the recording head to a recording medium to perform gradation recording.
There are, said scanning means for scanning a relatively said printing head against a recording medium, during the scanning of the printing head by said scanning means, said recording f
Said plurality of discharge ports of the head is divided into blocks of several, a division driving means when causing sequentially discharged for each block in said sequential ejection opening areas from a discharge block of a larger discharge port opening area the discharge interval to more discharge of blocks of small discharge opening, larger the opening area
Longer than the discharge gap between a plurality of blocks of deal of the discharge port
And a plurality of discharge ports each having the same opening area.
Drive timing control means for making the ejection intervals between the blocks equal to each other.
Printing is performed using a block with a large ejection port,
When recording a light part having a lower density than the dark part of the image
Using a discharge port block having a smaller opening area,
An ink jet recording apparatus for performing recording. 2. The ink jet recording apparatus according to claim 1 , wherein the recording head generates bubbles in the ink by using thermal energy, and discharges the ink as the bubbles are generated.