JPH03227633A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To make a recorded image uniform and obtain a high-quality image at high speed by controlling variably the waveform of an electric energy applied to a thermal resistor according to the ink discharge properties of each discharge aperture. CONSTITUTION:A recording signal is transferred to a shift register. If the recording signal is such as requiring an ink discharge, the shift register 1 causes pulse generators 2, 3, 4 to generate a trigger signal individually and subsequently, a pulse of specific width is generated in thermal resistors 8, 9, 10 of discharge apertures A, B, C beforehand so that the ink discharge amount becomes equal to a specified value in accordance with the discharge properties. Then switches 5, 6, 7 are turned ON. Thus pulses of different set widths run through the thermal resistors 8, 9, 10 at specified voltage and a fixed amount of ink droplets are discharged and splashed from the discharge apertures A, B, C. Therefore, a uniform image can always be obtained on the medium for recording.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inkjet recording device used in printers, facsimile machines, copying machines, etc., and in particular, the present invention relates to an inkjet recording device used in printers, facsimile machines, copying machines, etc. letter·
The present invention relates to an inkjet recording device that records images.

[Prior Art] An inkjet recording device uses a non-impact recording method and has attracted a lot of attention in recent years because it can produce relatively high-speed and high-quality recording.

Among them, the bubble jet method that uses thermal energy is being actively researched and developed because it is suitable for so-called full multi-printing of recording heads.

[Problems to be Solved by the Invention] However, in the conventional apparatus using a full multi-head having a large number of ejection ports, it is extremely difficult to obtain image uniformity of the recorded image. The reason for this is that the amount of ink ejected from each ejection port varies slightly. In terms of manufacturing technology, making the amount of ink ejected uniform is not only about making the ejection ports uniform in size, but also by making various characteristics such as the surface condition of the ejection ports and the thermal characteristics of the heating resistor uniform. This is extremely difficult in practice because it means measuring the amount of ink ejected, and the more the number of ejection ports increases, the more difficult it becomes to equalize the amount of ink ejected, which is a troublesome problem to be solved. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and to solve the problem that even if a fully multi-type inkjet recording head is used, which has non-uniform properties such as ejection ports, and the ink ejection amount is non-uniform, it is possible to It is an object of the present invention to provide an inkjet recording device that can consistently obtain high speed and high image quality with uniformity.

[Means for Solving the Problems] In order to achieve the above object, the present invention selectively applies electrical energy to a plurality of heating resistors provided respectively for a plurality of ejection ports in accordance with a recording signal. Accordingly, in an inkjet recording apparatus that records on a recording material by ejecting ink from the ejection ports, the electricity applied to the corresponding heat generating resistor is adjusted according to the ink ejection amount characteristics of each ejection port. The present invention is characterized in that it includes an electric energy waveform control means that varies the energy waveform so that the amount of ink ejected from each ejection port becomes uniform.

Further, in one aspect of the present invention, the electrical energy waveform control means changes the applied pulse width of the electrical energy.

The height of the applied pulse is changed, and the voltage and current of the applied pulse are changed. Change the duty using the chopping waveform. It is characterized by making the electrical energy waveform variable by at least one of the following: and changing the sub-heat pulse.

Further, in another aspect of the present invention, the electric energy waveform control means includes a signal generation means for individually generating a signal with an applied waveform fixedly determined in advance according to the resistance value of each of the heating resistors. It has different characteristics.

Further, in another aspect of the present invention, the electrical energy waveform control means includes a measuring means for measuring density characteristics of an image recorded on the recording material, and an image for each ejection port measured by the measuring means. Waveform selection means for selectively determining a waveform of electrical energy to be applied to each of the heating resistors corresponding to the concentration characteristics; and storing data of the waveform selected by the waveform selection means in correspondence to each of the heating resistors. The present invention is characterized in that it has a storage means for storing the waveform data, and a reading means for reading out the waveform data from the storage means in response to input of a recording signal.

[Function] In the present invention, since the pulse waveform applied to each ejection port is made variable according to the output characteristics of each ejection port, the amount of ink ejected from each ejection port is made uniform, and image quality is improved. is obtained.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic circuit configuration of a control system in a first embodiment of the present invention. In the same figure, ■ is a recording signal (image signal)
The input shift registers 2.degree.3.4 are pulse generators whose input sides are connected to the shift register 1, respectively, and which generate pulse signals with different pulse widths depending on the characteristics of the discharge ports.

5.6.7 is a switch that opens and closes (0N10FF) according to the pulse signal, and 8, 9.10 is a drive voltage, which causes the ink in each discharge hole A, B, and C to generate thermal energy that causes film boiling. This is a heating resistor (also referred to as an energizing heating resistor) provided in the.

First, in order to simplify the explanation, this embodiment will be described using an example in which it is assumed that the print head has three ejection ports. Here, it is assumed that the ejection amount characteristics of the ink droplets ejected from the ejection ports A, B, and C are shown in FIG. The horizontal axis in FIG. 2 represents the pulse width (μSec) of the current pulse applied to the heating resistors 8, 9, and 10 corresponding to the respective ejection ports A, B, and C, and the vertical axis represents the ink ejection amount (pl). ) is shown. For example, when the ink ejection amount is set to 20 pl (picoliters), the current pulse width applied to the heating resistors 8, 9, and 10 of the ejection ports A, B, and C is 7. 2
4Sec, 8.8g5ec, 8.84Sec.

Next, the operation of the circuit shown in FIG. 1 will be explained.

The recording signal is transferred to shift register 1. When the recording signal is a signal requiring ink ejection, the shift register 1 individually generates trigger signals to the pulse generators 2, 3.4. When this trigger signal is generated, the discharge ports A, B, and C are activated in advance.
The pulse generators 2, 3, .
4, a pulse with a set width is generated so that the ink ejection amount becomes 20 pl, and switches 5 and 6.7 are turned on. When switches 5 and 6.7 are turned on, heating resistors 8 and 9°lO
Pulses of different set widths at a predetermined voltage flow respectively.

For this reason, 20 pl can be obtained from any of the discharge ports A, B, and C.
A constant number of ink droplets are ejected and fly, making it possible to always obtain a uniform image on a recording material such as paper.

In addition to such pulse width modulation, variable control of the ink ejection amount is also possible by modulating the pulse height, that is, the output voltage or output current of the pulse, and the pulse waveform is a single rectangular waveform. It is not necessary (for example, it can be obtained by changing the duty ratio using a chopping wave, or by using a subheat pulse driving method as described later).

Furthermore, various methods are possible for determining the waveform of the pulse signal applied to each heating resistor 8, 9, 10. That is, in addition to the method of predetermining the waveform of the pulse signal from the ink ejection characteristics of each ejection port during manufacturing and setting it fixedly as described above, there is also a method of measuring the ejection characteristics at a user's arbitrary time. It was measured by a means (not shown) and was set in advance based on the measured value. A method of determining the waveform of the above-mentioned large signal using a CPU, etc. according to an algorithm, or focusing only on factors that greatly affect the ink ejection characteristics,
For example, a method of electrically measuring the resistance value of a heating resistor and determining a pulse waveform based on the measurement result can be applied.

11 prongs FIG. 3 shows a circuit configuration in a second embodiment of the present invention.

In the figure, 11 is a FIFO (
12 is a counter that counts up in synchronization with the clock; 13 is a waveform selection R that outputs an address signal for selecting a pulse waveform using the count value of the counter 12 as an address signal;
OM (Read Only Memory) 14 is a waveform ROM that generates a pulse waveform signal selected by an address signal from the ROM 13. 15 is an AND operation of the output signal of the register 11 and the output signal of the waveform ROM 14.
16 is a recording head. In the recording head 16, 17 is a shift register for storing a pulse signal manually inputted via AND gates 1-15, 18 is an AND gate, 19 is a heating resistor, and 20 is a power switch.

Here, it is assumed that a recording head 16 having 256 ejection ports is used.

In the above configuration, recording data is transferred to the FIFO register 11 in synchronization with the clock. Further, the counter 12 counts up in synchronization with this clock. For example, the pulse waveform applied to the first bit heating resistor 18 is:
It is determined as follows. That is, the address signal 1 indicating the first bit output from the counter 12 specifies the waveform number 0001 stored at address 1 of the waveform selection ROM 13. The output of the waveform number 0001 of the ROM 13 becomes the address signal of the waveform ROM 14, and the signal 111100 stored at the address 0001 of the ROM 14 is output in parallel 7 bits. Here, if the lth bit signal requires ejection, AND
“1” is input to the input terminal from the FIFO register 11 of the gate 15.
" is set, and as a result, the output signal from the waveform ROM 14 is input to the 7-bit shift register 17 of the recording head 16. On the other hand, if the signal of the first bit does not require ejection, the input terminal of the AND gate 15 is 0, so A
All outputs of the ND gate 15 become O.

The 7-bit signal input to the recording head 16 corresponds to a waveform as shown in FIG. By using a driving waveform divided into two pulses in this manner, it is possible to widen the modulation range of the ink ejection amount.

In this example, the recording head 1 is set in advance under the same driving pulse conditions.
6 to measure the ejection amount of the 256 ejection ports, and apply the voltage to each heating resistor 19 by referring to the relationship between the pulse waveform and the ejection amount experimentally obtained from the measurement results. The address of the waveform ROM 14 in which the determined pulse waveform is stored is stored in the waveform selection ROM 1.
Enter 3.

Actually, the applied voltage was 20V and the maximum pulse width was 12μSec.
Under these conditions, when a uniform pulse with a pulse width of 9 μsec was applied to the heating resistor 19, the printed dot diameter was 110 μm±.
Although there was a variation of 50 μm, the printed dot diameter was reduced to 110 μm ± 20 μm due to the bit-based correction processing of this embodiment.
It was confirmed that there was a variation in m, and that a substantially uniform image was obtained.

Figure 5 shows the circuit configuration of the third embodiment of the present invention, which reads an image once recorded on paper and calculates the pulses to be applied to each heating resistor according to the density distribution of the image. An example of determining the waveform is shown. In the figure, 21 is an illumination light source (lamp)
, 22 is a sheet of paper, 23 is a lens that collects reflected light from the recorded image on the sheet, and 24 is a CCD (CCD) that converts the image formed through the lens 23 into an electrical signal by photoelectric conversion.
charge-coupled device). 25 is an OD-pulse waveform compatible ROM which will be described later, 26 is a waveform RAM (random access memory) which will be described later, 27 is a counter that counts up with a clock, 28 is a shift register to which recording data is transferred, and 29 is an output of the waveform RAM. shift register 28
This is an AND gate that matches the output of . 30 is a recording head having a shift register 31 and the like.

Next, the operation of this embodiment will be explained.

An image recorded on a paper surface 22 under uniform conditions of an applied voltage of 20 V and a pulse width of 8 uSec is illuminated by a lamp 21, and the reflected light is read by a CCD 24 via a lens 23. The reading density at this time is equal to the recording density, 16 pel/mm.
The first bit of recording corresponds to the first bit of reading. The CCD output signal obtained via a smoothing circuit (not shown) is then input to the OD-pulse waveform compatible ROM 25 via an A/D converter (not shown) so that the recorded dot diameter corresponds to the density signal. . This ROM 25 is arranged with waveform data of a pulse waveform in which the dot diameter becomes larger for low concentration data, and conversely, the dot diameter becomes smaller for high concentration data, based on the results obtained from experiments in advance. (The waveform data of the pulse waveform is arranged as follows.The actual values of the correspondence between the read density, the pulse waveform, and the waveform data are, for example, as shown in FIG. 6 in this embodiment.

As described above, the waveform data sequentially determined from the first bit by the OD-pulse waveform compatible ROM 25 is recorded in the waveform RAM 26.

In this example, data of 4736 bits (16pl-A3) is handled.

Next, recording data is input to the shift register 28 in synchronization with a clock (for example, 12MH clock). Next, in synchronization with the output of the recording data from the shift register 28 in synchronization with the clock, 5-bit data is output from the waveform RAM 26 according to the output address of the counter 27, and is passed through the AND gate 29 to the shift register of the recording head 30. 31
Enter.

This recording head 30 has a 3-bit and a 2-bit counter 3.
2.33, the set-up value of the counter 32.33 is specified, and an applied pulse is outputted by each counter clock of pc, , pc, and the heating resistor 36
to drive.

In this embodiment, in order to further improve the uniformity of the recorded image, it is preferable to repeat the above-mentioned operation multiple times. That is, by reading the recorded image, determining the pulse waveform, rereading the recorded image using the determined pulse waveform, and determining the pulse waveform again, uniformity of the recorded image can be more effectively obtained. It was confirmed that this is possible.

(Others) The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

This is because such a system can achieve higher recording density and higher definition.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse-shaped drive signal is described in U.S. Pat. Nos. 4,463,359 and 4,345,262.
Those described in the specification are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the wafer is placed in a bending region. In addition, Japanese Patent Application Laid-Open No. 5-1999 discloses a configuration in which a common slit is used as a discharge part of the electrothermal converters for a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
The effects of the present invention are also effective even if the structure is based on the publication No.-138461. In other words, regardless of the form of the recording head, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally. In addition, even the serial type shown above can be installed on the main body of the device, allowing for electrical connection to the main body of the device and supply of ink from the main body of the device.Replaceable chip type recording heads. Alternatively, the present invention is also effective when using a cartridge type recording head that is integrally provided with the recording head itself.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus, to the present invention, because the effects of the present invention can be further stabilized. Specifically, these include capping means for the recording head, cleaning means, pressure or suction means, preheating means using an electrothermal transducer or another heating element, or a combination thereof; It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal for information processing equipment such as a computer, a photographic device combined with a league, etc., and a facsimile device having a transmission/reception function. It doesn't matter what you pick.

[Effects of the Invention] As described above, according to the present invention, the pulse waveform applied to each heat generating resistor is made variable in the amount of ink ejected from each ejection port in accordance with the output characteristics of each ejection port. As a result, the amount of ink ejected from each ejection port can be made uniform even in a recording head having non-uniform ejection characteristics. As a result, according to the present invention, it is possible to obtain high image quality even in high-speed printing using a full multi-print head having a large number of ejection ports.

In addition, in order to obtain a uniformity that can withstand practical use, the yield in the manufacturing process of recording heads was conventionally extremely low, causing an increase in manufacturing costs, but with the present invention, This makes it possible to set standards for the uniformity of usable recording heads that are more lenient than in the past, which also has the effect of reducing manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the circuit configuration of the first embodiment of the present invention, and Fig. 2 shows an example of the relationship between the pulse width of the pulse applied to the heat generating resistor and the amount of ink ejected in the embodiment of Fig. 1. 3 is a block diagram showing the circuit configuration of the second embodiment of the present invention, FIG. 4 is a waveform diagram showing an example of the waveform of the pulse signal stored in the waveform ROM of FIG. 3, and FIG. A block diagram showing the circuit configuration of the third embodiment of the present invention. FIG. 6 is an explanatory diagram showing an example of the relative relationship between the image reading density, the output pulse waveform, and the waveform data in the embodiment of FIG. 1...Shift register, 2,3.4...Pulse generator, 8,9.10...Heating resistor, 11...FIFO register, 12...Counter, 13...Waveform selection ROM, 14... Waveform ROM, 15... AND gate, 16... Recording head, 19... Heating resistor, 24... CCD. 25... OD-pulse waveform compatible ROMz6... Waveform RAM. 30...recording head. Figure (pi) Figure 2 ○ Figure 4

Claims (1)

[Claims] 1) Electrical energy is selectively applied to a plurality of heating resistors provided for each of the plurality of ejection ports in accordance with a recording signal, so that ink is ejected from the ejection port. In an inkjet recording apparatus that performs recording on a recording material, the waveform of the electrical energy applied to the corresponding heating resistor is determined according to the ink ejection amount characteristics of each ejection port. 1. An inkjet recording apparatus comprising an electric energy waveform control means that varies the electric energy waveform so that the electric energy waveform is uniform. 2) The electrical energy waveform control means changes the applied pulse width of the electrical energy, changes the applied pulse height, changes the voltage and current of the applied pulse, changes the duty with a chopping waveform, and subheats. 2. The inkjet recording apparatus according to claim 1, wherein the electrical energy waveform is made variable by at least one of the following: changing a pulse. 3) The electric energy waveform control means has a signal generation means for individually generating a signal with an applied waveform fixedly determined in advance according to the resistance value of each of the heating resistors. or 2. The inkjet recording device according to 2. 4) The electrical energy waveform control means includes: a measuring means for measuring the density characteristics of the image recorded on the recording material; Waveform selection means for selectively determining the waveform of electrical energy to be applied to the heating resistor; Storage means for storing data of the waveform selected by the waveform selection means in association with each of the heating resistors; 3. The inkjet recording apparatus according to claim 1, further comprising readout means for reading out the waveform data from the storage means in accordance with an input. 5) The inkjet recording according to any one of claims 1 to 4, wherein the electric energy applied to the heating resistor is a pulse signal that causes film boiling in the ink of the recording head to eject the ink. Device.