JP2774636B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus used for a printer, a facsimile apparatus, a copying machine, and the like, and more particularly, to an ink jet recording apparatus which discharges ink from a discharge port toward a recording material. The present invention relates to an ink jet recording apparatus that records characters and images.

[Related Art] An ink jet recording apparatus is of a non-impact recording type, and can obtain relatively high-speed and high-quality recording. Among them, the bubble jet type utilizing thermal energy is suitable for so-called full multi-recording heads, and therefore, research and development are being actively promoted.

[Problems to be Solved by the Invention] However, in a conventional apparatus using a full multi-head having a large number of ejection ports, it is extremely difficult to obtain image uniformity of a recorded image. The reason is that the amount of ink ejected from each ejection port varies slightly. Making the ink discharge amount uniform in terms of manufacturing technology not only measures the dimensional uniformity of the discharge ports, but also
In practice, this means to equalize various structural characteristics such as the surface condition of the discharge port and the thermal characteristics of the heating resistor for discharging ink from the discharge port. As the number of outlets is increased, the difficulty in making the ink ejection amount uniform is increased.

Therefore, an object of the present invention is to solve the above-described problem, and to achieve uniformity of a recorded image even when using an inkjet recording head that causes variation in the amount of ink protrusion based on non-uniformity of structural characteristics such as ejection ports. It is an object of the present invention to provide an ink jet recording apparatus which can always obtain high speed and high image quality by obtaining the image quality.

[Means for Solving the Problems] In order to achieve the above object, the invention of claim 1 selectively supplies electric energy to a plurality of heating resistors provided for a plurality of discharge ports in accordance with a recording signal. In order to suppress the variation in the amount of ink ejected from each ejection port due to structural non-uniformity in an ink jet recording apparatus in which ink is ejected from the ejection port to perform recording on a recording material by applying And an electric energy waveform control means for controlling a waveform of the electric energy applied to the heating resistor corresponding to each of the ejection ports so as to make an amount of ink ejected from each of the ejection ports uniform. The means has signal generating means for individually generating a signal of an application waveform fixedly determined in advance in accordance with the resistance value of each of the heating resistors for each of the heating resistors. Features.

Here, the electric energy waveform control means changes at least one of an applied pulse width of the electric energy, an applied pulse height, a voltage / current of the applied pulse, a duty in a chopping waveform, and a sub-heat pulse. Control can be performed.

Further, the electric energy applied to the heating resistor may be a pulse signal for causing ink of the recording head to cause film boiling and ejecting the ink.

[Operation] In the present invention, in order to suppress the variation in the ink ejection amount based on the structural nonuniformity of each ejection port or the like, an application fixedly determined in advance in accordance with the resistance value of each heating resistor. Since the waveform signal is individually generated for each of the heating resistors, the ink ejection amount from each ejection port can be made uniform, and the image quality can be improved.

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

First Embodiment FIG. 1 shows a schematic circuit configuration of a control system according to a first embodiment of the present invention. In the figure, 1 is a shift register to which a recording signal (image signal) is input, and 2, 3, and 4 each have an input side connected to the shift register 1 and have different pulse widths according to the structural characteristics of the ejection port. It is a pulse generator that generates a pulse signal. 5, 6, 7 are ON / OF by the pulse signal
F (open / close) switches, 8, 9, and 10 are drive voltages, and heat-generating resistors (electric heating) provided in each of the ejection openings A, B, and C that generate heat energy that causes film boiling of ink. (Also referred to as a resistor).

First, for the sake of simplicity, the ejection port of the recording head is 3
The present embodiment will be described by taking as an example a case where it is assumed that there is one. 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 indicates the pulse width τ (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 indicates the ink ejection amount (pl). ). For example, when the ink discharge amount is set to 20 pl (picoliter), the current pulse width applied to each of the heating resistors 8, 9, and 10 of the discharge ports A, B, and C is 7.2 μsec from the characteristics shown in FIG. , 8.8 μSec, 8.8 μSec.

 Next, the operation of the circuit of FIG. 1 will be described.

The recording signal is transferred to the shift register 1. If the recording signal is a signal requiring ink ejection, the shift register 1
Generates trigger signals individually for the pulse generators 2, 3, and 4.
When this trigger signal is generated, pulse generators 2, 3, and 4 in which pulse widths to be applied to the heating resistors 8, 9, and 10 of the discharge ports A, B, and C are set in advance according to the generation amount characteristics of each discharge port. Generates a pulse of the set width so that the ink discharge amount becomes 20pl, and the switch
Turn on 5,6,7. When the switches 5, 6, and 7 are turned on, pulses of different setting widths at a predetermined voltage flow through the heating resistors 8, 9, and 10, respectively. For this reason, 20p from any of the outlets A, B, and C
A constant ink droplet of l is ejected and flies, and a uniform image can always be obtained on a recording material such as paper.

In addition to such pulse width modulation, the 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, the duty ratio can be changed by a chopping wave, or a sub-heat pulse driving method described later can be used.

In addition, various methods are available for determining the waveform of the pulse signal applied to each of the heating resistors 8, 9, and 10. That is, as described above, in addition to the method of previously determining the waveform of the pulse signal from the ink ejection characteristics of each ejection port at the time of manufacturing and fixedly setting the ink ejection characteristics, the ejection characteristics are measured at an arbitrary time of the user. A method of determining the waveform of the pulse signal by a CPU or the like according to an algorithm set in advance based on the measured value and measuring the measured value by means (not shown), or focusing only on factors that greatly affect ink ejection characteristics, for example, A method of electrically measuring the resistance value of the heating resistor and determining a pulse waveform based on the measurement result can be applied.

Second Embodiment FIG. 3 shows a circuit configuration in a second embodiment of the present invention. In the figure, reference numeral 11 denotes a FIFO (fast-in / fast-out) register to which recording data is input, 12 a counter that counts up in synchronization with a clock, and 13 a counter.
A waveform selection ROM (read only memory) that outputs an address signal for selecting a pulse waveform using the count value of 12 as an address signal, and 14 is a waveform ROM that generates a signal of a pulse waveform selected by the address signal from the ROM 13. is there. Reference numeral 15 denotes an AND gate that calculates the logical product of the output signal of the register 11 and the output signal of the waveform ROM 14, and 16 denotes a recording head. In the recording head 16, reference numeral 17 denotes a shift register for storing a pulse signal input via the AND gate 15, reference numeral 18 denotes an AND gate, reference numeral 19 denotes a heating resistor, and reference numeral 20 denotes a power switch.

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

In the above configuration, the recording data is transferred to the FIFO register 11 in synchronization with the clock. The counter 12 counts up in synchronization with this clock. For example, the pulse waveform applied to the first-bit heating resistor 18 is determined as follows. That is, the waveform number 0001 stored at the address 1 of the waveform selection ROM 13 is designated by the address signal 1 indicating the first bit output from the counter 12. The output of the waveform number 0001 of the ROM 13 becomes an 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 signal of the first bit requires ejection,
“1” rises at the input terminal from the FIFO register 11 of the D gate 15, whereby the output signal from the waveform ROM 14 is
6 is input to the 7-bit shift register 17. On the other hand, if the signal of the first bit does not require ejection, the input terminal of the AND gate 15 becomes 0, so that the outputs of the AND gate 15 all become 0.

The 7-bit signal input to the recording head 16 has a waveform as shown in FIG. By using the waveform that is divided into two pulses and driven, the modulation range of the ink ejection amount can be increased.

In this example, the recording head was previously set under the same driving pulse conditions.
Measure the discharge amount of 256 discharge ports by driving 16 and apply it to each heating resistor 19 by referring to the relationship between the pulse waveform and the discharge amount obtained experimentally in advance from the measurement result The pulse waveform to be determined is determined, and the address of the waveform ROM 14 storing the determined pulse waveform is input to the waveform selection ROM 13.

Actually, under the conditions of an applied voltage of 20 V and a maximum pulse width of 12 μSec, a uniform pulse having a pulse width of 9 μSec is used to generate the heating resistor 19.
When the dot was applied, the print dot diameter had a variation of 110 μm ± 50 μm.However, the print dot diameter became a variation of 110 μm ± 20 μm by the bit corresponding correction processing of this embodiment, and a substantially uniform image could be obtained. It could be confirmed.

Third Embodiment FIG. 5 shows a circuit configuration of a third embodiment of the present invention, in which an image once recorded on a sheet of paper is read, and a pulse waveform to be applied to each heating resistor according to the density distribution of the image. Here is an example of determining. In the figure, 21 is an illumination light source (lamp), 22 is a sheet, 23 is a lens for condensing light reflected from a recorded image on the sheet, and 24 is an electric image formed via a lens 23 by photoelectric conversion. It is a CCD (Charge Coupled Device) that converts it into a signal. 25 is an OD-pulse waveform corresponding ROM described later, 26 is a waveform RAM (random access memory) described later, 27 is a counter that counts up by a clock, 28 is a shift register to which recording data is transferred, and 29 is an output of the waveform RAM. This is an AND gate that matches the output of the shift register 28. Three
Reference numeral 0 denotes a recording head having the shift register 31 and the like.

 Next, the operation of this embodiment will be described.

The image recorded on the paper surface 22 is illuminated by the lamp 21 under the uniform conditions of the applied voltage of 20 V and the pulse width of 8 μSec, and the reflected light is read by the CCD through the lens. The reading density at this time is equal to the recording density and is 16 pel / mm, and the first bit of recording corresponds to the first bit of reading. The CCD output signal obtained through a smoothing circuit (not shown) so that the recorded dot diameter corresponds to the density signal is then converted to an OD-pulse waveform ROM 2 through an A / D converter (not shown).
Enter 5 In the ROM 25, based on the results obtained in advance by experiments, waveform data of a pulse waveform that increases the dot diameter for low-density data is arranged, and conversely, the dot diameter decreases for high-density data. The waveform data of the following pulse waveforms are arranged. 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 corresponding ROM 25 is stored in the waveform RAM 2.
Recorded in 6.

In this example, it is assumed that data of 4736 bits (16pl · A3) is handled.

Next, recording data is input to the shift register 28 in synchronism with the clock (e.g. 12MH _z). Next, in synchronization with the output of the recording data from the shift register 28 in synchronization with the clock, the waveform RAM 26
And outputs 5-bit data, which is input to the shift register 31 of the recording head 30 through the AND gate 29.

This recording head 30 has a 3-bit and 2-bit counter 3
2, 33, and by specifying the setup value of the counters 32, 33, by the counter clock of each of PC ₁ and PC ₂ ,
The heating pulse 36 is driven by outputting the applied pulse.

In this embodiment, in order to further improve the uniformity of the recorded image, the above operation may be repeated a plurality of times. That is,
By reading the recorded image, determining the pulse waveform, re-reading the image recorded with the determined pulse waveform, and determining the pulse waveform again, the uniformity of the recorded image can be obtained more effectively. Was confirmed.

(Others) The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet system among ink jet recording systems. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to a sheet or a liquid path holding a liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, thereby causing the recording head to emit heat energy. This is effective because a film in the liquid (ink) corresponding to the driving signal can be formed one by one by causing film boiling on the heat acting surface. 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. U.S. Pat. No. 44
Those described in JP-A-63359 and JP-A-4345262 are suitable. Further, when 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 a configuration of the recording head, in addition to the combination configuration (straight-line liquid flow path or right-angled liquid flow path) of the discharge port, the liquid path, and the electrothermal converter as disclosed in the above-mentioned specifications, a thermal action A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600, which discloses a configuration in which a portion is arranged in a bending region, 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 an 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 is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, recording can be performed reliably and efficiently regardless of the form of the recording head.

Further, 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 on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head. In addition, a replaceable chip-type recording head that can be electrically connected to the device main body or supplied with ink from the device main body by being attached to the device main body even in the serial type as described above. The present invention is also effective when a cartridge type recording head provided integrally with the recording head itself is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different print colors and densities. May be used.

In addition, the form of the ink jet recording apparatus of the present invention may be 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, or a facsimile apparatus having a transmission / reception function. It may be something.

[Effects of the Invention] As described above, according to the present invention, the ejection amount of ink from each ejection port is controlled so as to suppress the variation in ejection characteristics based on the structural nonuniformity of each ejection port. A signal of an application waveform fixedly determined in advance according to the resistance value of each heating resistor is generated individually for each heating resistor. The amount of ink discharged from the discharge port becomes uniform. 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-recording head having an extremely large number of ejection ports.

In addition, in order to obtain uniformity that can withstand practical use, the yield (yield) in the manufacturing process of a recording head has been extremely low in the past, causing an increase in manufacturing cost. This makes it possible to set a looser standard for the uniformity of usable recording heads than in the past, and also has the effect of reducing manufacturing costs.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a first embodiment of the present invention, and FIG. 2 shows an example of a relationship between a pulse width of a pulse applied to a heating resistor and an ink ejection amount in the embodiment of FIG. FIG. 3 is a block diagram showing a circuit configuration of a second embodiment of the present invention, FIG. 4 is a waveform diagram showing an example of a pulse signal stored in the waveform ROM of FIG. 3, and FIG. FIG. 6 is a block diagram showing a circuit configuration of a third embodiment of the present invention. FIG. 6 is an explanatory diagram showing an example of a relative relationship among image reading density, output pulse waveform, and waveform data in the embodiment of FIG. 1… Shift register, 2,3,4… Pulse generator, 8,9,10… Heat generating 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 ROM, 26: Waveform RAM, 30: Recording head.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiko Takekoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-2-4085 (JP, A) JP-A-2-2 -172755 (JP, A) JP-A-3-166959 (JP, A) JP-A-62-286747 (JP, A) JP-A-64-47554 (JP, A) (58) Fields investigated (Int. . ^6, DB name) B41J 2 / 05,2 / 125

Claims (3)

(57) [Claims] An ink is ejected from said discharge ports by selectively applying electric energy to a plurality of heating resistors provided for each of said plurality of discharge ports in accordance with a recording signal. In the ink jet recording apparatus which performs recording on the upper surface, the electric energy applied to the heating resistor corresponding to each of the ejection ports in order to suppress a variation in the amount of ink ejected from each of the ejection ports due to structural non-uniformity. Electrical energy waveform control means for controlling the waveform of the ink so as to equalize the amount of ink ejected from each of the ejection ports. The electric energy waveform control means is fixed in advance in advance in accordance with the resistance value of each of the heating resistors. An ink jet recording apparatus, comprising: signal generating means for individually generating a signal of the determined applied waveform for each of the heating resistors. 2. The electric energy waveform control means changes at least one of an applied pulse width of the electric energy, an applied pulse height, a voltage / current of the applied pulse, a duty in a chopping waveform, and a sub-heat pulse. The inkjet recording apparatus according to claim 1, wherein the control is performed by causing the control. 3. The ink jet recording apparatus according to claim 1, wherein the electric energy applied to the heating resistor is a pulse signal for causing the ink of the recording head to cause film boiling and ejecting the ink. apparatus.