JPH07137240A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To correct mishitting due to differences in discharge volume by performing a time-division drive properly when a serial scan mode of recording is made, using a recording head equipped with multiple discharge openings of different areas. CONSTITUTION:Code 3 is a generation circuit 1, a delay circuit 2 and a 10-MHz oscillation circuit to output a clock pulse as a reference for a set time in each block as explained below. Codes 4 and 5 are trigger pulse signal generation circuits to output four pulses of 1musec. in width at an interval of 20musecs. These circuits output signals C and D. Signals Seg 0 to Seg 7 which selects one out of eight blocks of the recording head to drive are outputted from segment signal generation circuits 6 and 7, respectively.

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 ejecting ink onto a recording medium for recording.
Specifically, it relates to ejection timing control.

[0002]

2. Description of the Related Art The ejection timing control in a recording head of a conventional ink jet recording apparatus is roughly classified into two systems, that is, simultaneous drive for all ejection ports and time-divisional drive for several ejection ports.

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

By the way, when the recording head and the driving method are used in a printer (recording apparatus) of the serial scanning method, for example, when 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 displaced by 4 μm in the scanning direction. In this case, since the printing results (ink dots) by ejection from each block have a slope, a configuration for correcting this has been proposed conventionally. 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 enhance the gradation of recorded images as one of the measures to meet the recent demand for higher image quality of printer output images. As one of them, a single recording head is provided with ejection ports having different opening areas, whereby different sizes (hereinafter referred to as ejection amounts) of ejected ink droplets are formed on a recording medium. It has been proposed that different sizes of ink dots can be used to express various densities.

However, when such a recording head is used, the ejection speed of the ink ejected from the ejection port with a small ejection amount (small opening area) is large with the ink ejection amount (large opening area). The discharge time is faster than the discharge speed and the time required to reach the recording medium such as recording paper is different. In this case, in the method of recording while moving the recording head (serial scan method), there is a problem in that the ink landing position is displaced, resulting in deterioration of image quality (see FIG. 9).

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to perform serial scan recording using a recording head having a plurality of ejection openings having different opening areas. An object of the present invention is to provide an inkjet recording apparatus capable of performing recording with good image quality by correcting the landing position shift caused by the difference in ejection amount by appropriately performing time-division driving.

[0009]

Therefore, according to the present invention,
In an ink jet recording apparatus that uses a recording head having a plurality of ejection ports having different opening areas and ejects ink from the recording head to a recording medium to perform recording, a scanning unit that causes the recording head to scan, and a plurality of the ejection units. The outlet is divided into a plurality of blocks according to the opening area, and the time-division drive unit that sequentially discharges each block, and in the sequential discharge, the discharge from the block having the discharge opening having the larger opening area to the discharge having the smaller opening area Drive timing control means for making the discharge interval until the discharge of the block of the outlet longer than the discharge interval between the blocks of the discharge ports having the same opening area.

More specifically, the present invention will be described in more detail. For example, as shown in FIG. 10A, in order to correct the inclination of the recording result by the time-divisional drive described above, even if the ejection port array is inclined, it is large. As the ink from the ejection port having the opening area has a different landing position, the result shown in FIG. 10B is obtained. On the other hand, the recording result as shown in FIG. 10C can be obtained by correcting the landing position deviation according to the difference in the opening area of the ejection port of the present invention.

As a configuration for this, as shown in FIG. 11, a predetermined delay time (for example, 41.7 μm) is provided 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 the time-divisional driving in which the recording head having the smaller ejection opening diameter is ejected first, the timing correction as shown in FIG. 12 is required.
In this case, the driving pulses of the third and fourth blocks overlap with the driving pulses of the fifth and sixth blocks, which makes sense of time-division driving. Therefore, it is preferable to perform the driving order from the ejection port having a large diameter.

[0013]

According to the above construction, since a discharge interval longer than usual is set (delayed) between the discharge of a block having a large opening area and the discharge of a block having a smaller opening area, the discharge speed of the discharge opening having a large opening area is increased. Even if it is later, the ejection from the ejection port having a small opening area is delayed, so that the difference in the ejection speed is offset and the deviation of the landing position of the ejected ink is corrected.

[0014]

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

(Embodiment 1) FIG. 3 is a schematic perspective view of a recording head according to an embodiment of the present invention.

This recording head has 32 large-diameter recording ejection openings with a large opening area (diameter of about 30 μm) on the upper side, and a small-area recording ejection opening 3 with small opening area (diameter of about 15 μm) 3.
Two of them are arranged in a straight line at the bottom, and these 64 discharge ports are simultaneously discharged from one block consisting of eight continuous discharge ports, and 8 blocks are sequentially arranged at predetermined intervals for each block. Is ejected. FIG. 4 shows a connection diagram of the discharge heaters in the respective discharge ports, and the discharge heaters are driven for each block to discharge from the respective discharge ports.

The ink jet recording apparatus for performing the serial scan type recording using the recording head shown in FIG. 3 is the same as the known one except the ejection timing control which will be 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 feeding direction of the recording paper, and ink is ejected from the recording head in accordance with this movement to perform recording. To do. Here, first, in the first scan, the 32 light-part recording ejection ports below the recording head eject based on the recording data, and then the recording paper is conveyed by a distance corresponding to 32 ejection ports. Ejection is performed from the 32 dark-area recording ejection ports above the recording head in two scans, and an image with a width of 32 ejection ports is recorded in two scans.

Of course, in the above description, when discharge is made from the dark part recording discharge port, the lower light recording part discharge port discharges to the next row.

FIG. 1 and FIG. 2 are for explaining the ejection timing control according to the first embodiment of the present invention.
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. Output A.
Reference numeral 2 indicates the pulse signal A output from the generation circuit 1 as CP.
The time set by U (1 in the timing chart of FIG. 2)
21.7 .mu.sec.), Which 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 that 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 intervals of 20 μsec. , And outputs the signals C and D shown in FIG. 2, respectively. Based on these signals C and D, the segment signal generation circuits 6 and 7 output signals (segment signals) Seg0 to Seg7 for selectively driving one of the eight blocks of the recording head. The segment signals Seg0 to Seg3 correspond to the signal C, and Seg4 is a signal for driving the discharge heater in the dark portion of the print head.
.About.Seg7 correspond to the signal D and are connected in the recording head portion as a signal for driving the discharge heater in the light portion of the recording head.

As described above, the difference in the time taken for the ejected ink to reach the recording medium, as shown in FIG. 9, between the block of the large diameter ejection port and the block of the small diameter ejection port is 4
The 1.7 μs can be eliminated by setting a delay time of 41.7 μs between the end of the pulse of the group of signals C and the beginning of the pulse of the group of signals D, and the landing position of the landing position due to the difference in the arrival time of the ejected ink can be eliminated. The gap can be eliminated.

Each segment signal outputs one pulse for about 15 μsec from the falling edges of the signals C and D.
At this time, the data from the image memory 8 (hereinafter abbreviated as RAM) latched by the data latch circuit 9 by the rising edge signals of the signals C and D (signal E in FIG. 2) is output to the data line of the recording head. . In order to prepare the data of the next block after the end of the latch, the output of the read address counter circuit 10 of the RAM 8 counts up by 1 in response to the falling edge signals of the signals C and D (signal F of FIG. 2) (FIG. 2). A15-A0). R
The address of AM8 is counted up from 0000H to 5CFFH during recording of one line (one scan) (when 2976 dots are recorded in the scan direction: 29).
76 * 8 = 23808 = 5D00H), address is 5D
At the moment when the address reaches 00H (the set value of the register 11), the output of the comparator 12 stops the operation of the 4 KHz pulse signal generation circuit.

The above is an explanation of the operation of the circuit shown in FIG. 1 when recording data for one line. Before the start of recording the next line, the CPU reads the RAM read address to 0000H and the CPU outputs a clear signal. Is output and then the above sequence is restarted.

The CPU outputs a start signal at the start of recording one line, and 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, A15 becomes "1" when recording an odd-numbered line, and
The address of RAM8 is 8000H to DCFFH, and A15 is "0" when the even-numbered line is recorded. Therefore, the address of RAM8 is 0000.
It goes from H to 5 CFFH. The image data in RAM is
As shown in FIG. 16, the CPU rearranges and writes the data sent via the interface.

(Embodiment 2) In the above-described Embodiment 1, it was attempted to correct the landing position deviation by controlling the drive timing between the blocks having different ejection port diameters.
As shown in FIG. 3, a timing control circuit can be inserted in all the ejection ports.

That is, in FIG. 13, reference numeral 201 indicates an oscillation circuit of 10 MHz which is a basic clock of this circuit, and reference numeral 202 is a pulse which receives a recording start trigger signal from the CPU and starts oscillation at 4 KHz. A signal generation circuit is shown, and this circuit 202 outputs the signal A shown in FIG. Reference numeral 203 is a short pulse B shown in FIG. 14 in response to signals from the oscillation circuit 201 and the generation circuit 202.
8 is a data trigger pulse signal generating circuit, and reference numeral 204 is a data latch signal generating circuit which receives the rising edge of this pulse and successively generates the data latch signals C0 to C7 shown in FIG. 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, and the address of the RAM 206 is rewritten before the output of the signals C0 to C7 and the data bus. It is for sequentially outputting the data above. These output data are data latch circuits 207 to 21.
4 are respectively latched corresponding to the ejection ports of the recording head. The enable signal generation circuit 215 receives signals from the generation circuit 202 and the generation circuit 203, and the enable signal generation circuit 215 outputs from the discharge heater driving signal A of each discharge port (set by the CPU in advance). 14 and the signal E0 to E63 shown in FIG. 14 are output depending on the delay time and the voltage application time to the discharge heater.

The discharge heater of the print head corresponding to the circuit of this structure requires one voltage application terminal and 64 data terminals as shown in FIG. 15, and the heater structure of the first embodiment described above. There are more signal lines than (see Fig. 4),
Although the circuit scale becomes large, on the other hand, since it is possible to make a fine timing correction and adjust the heater application time between the ejection ports, it is possible to obtain a higher quality output.

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

The time division drive to which the present invention is applied is
The present invention is not limited to one in which a plurality of continuous ejection ports are used as one block, and can be applied to time-division driving in which the ejection ports are dispersed to form one block.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection to the main body of the apparatus and the ink from the main body of the apparatus by being attached to the main body of the apparatus. 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 integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add ejection recovery means of the recording head, preliminary auxiliary means and the like because the effect of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the 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, as the form of the ink jet recording apparatus of the present invention, other than the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function are provided. It may be a form or the like.

[0038]

As described above, according to the present invention,
Since a longer ejection interval than usual is set (delayed) between the ejection of a block with a large opening area and the ejection of a block with a small opening area, even if the ejection speed of an ejection opening with a large opening area is slower, ejection with a smaller opening area is performed. Since the ejection at the outlet is delayed, the difference in the ejection speed is offset by this, and the deviation of the landing position of the ejected ink is corrected.

As a result, it is possible to output a high quality image.

[Brief description of 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 above circuit.

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

FIG. 4 is a schematic diagram showing the connection of ejection heaters 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 array of a conventional recording head and a recording result.

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

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

FIG. 9 is an explanatory diagram illustrating occurrence of landing position deviation of ejected ink from each of the large diameter ejection port and the small diameter ejection port.

10A to 10C are explanatory views for explaining the correction of the landing position deviation according to the present invention.

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

FIG. 12 is a timing chart showing correction according to the present invention when ejecting from a small diameter ejection port.

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

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

FIG. 15 is a schematic diagram showing the connection of ejection heaters of the recording head used in the second embodiment.

FIG. 16 is a schematic diagram showing a memory map of image data stored in the 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 to 214 Data latch Circuits 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

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Claims (3)

[Claims] 1. An inkjet recording apparatus for recording by using a recording head having a plurality of ejection openings having different opening areas and ejecting ink from the recording head to a recording medium, and a scanning unit for scanning the recording head. A time-division driving unit that divides the plurality of discharge ports into a plurality of blocks for each opening area and sequentially discharges each block; and, in the sequential discharge, discharge from a block of a discharge port having a larger opening area An ink jet recording apparatus comprising: drive timing control means for setting a discharge interval up to the discharge of a block of discharge ports having a smaller area to be longer than a discharge interval between blocks of discharge ports having the same opening area. 2. The ink jet recording apparatus according to claim 1, wherein in the sequential driving, the block ejected in advance is a block of an ejection port having a large opening area. 3. The ink jet recording according to claim 1, wherein the recording head uses the thermal energy to generate bubbles in the ink and ejects the ink in association with the generation of the bubbles. apparatus.