JP2690773B2 - Ink jet recording apparatus and ink jet recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inkjet recording apparatus and an inkjet recording method used in printers, facsimiles, copiers, and the like, and more specifically, generates thermal energy used for ink ejection. The present invention relates to an inkjet recording device and an inkjet recording method using an electrothermal converter as a means.

[Prior Art] A recording head of an apparatus using this type of electrothermal converter is
It has the advantage that it can be manufactured by the same process as the semiconductor device manufacturing process that has been significantly developed recently, and that it enables high density and multi-nozzle discharge ports and high-definition recording. ing.

In addition, mass production and cost reduction can be realized by the above manufacturing process, and a disposable recording head is being realized.

[Problems to be Solved by the Invention] Although the above-described recording head manufacturing process has a considerable degree of reproducibility in terms of its shape and the like, due to the multi-nozzle structure, there is a slight gap between each of a large number of ejection ports. There may be a difference in shape. Further, in the case of the disposable type recording head, there may be a solid difference in the manufacturing between the recording heads.

Further, due to the increase in the density of the ejection ports, the ratio of the distance between the ejection ports to the distance (pitch) between the ejection ports and the recording medium that faces the ejection ports becomes larger than that of the conventional one. A variation, for example, a variation in the ejection port pitch, an ink ejection direction, or the like, is prominent as a variation in pixels to be formed.

Furthermore, there may be variations in the performance of the electrothermal converter provided for each ejection port and the shape of the ink liquid chamber or the like communicating with the ejection port.

As described above, as a result of various variations of each ejection port, the array of dots formed by ink ejection becomes non-uniform, and due to this non-uniform dot array, streaks or the like are generated in the finally formed image. However, the image quality may be degraded.

The present invention has been made in view of the above-described conventional problems, and an object thereof is to reduce the image quality by changing the ink ejection amount according to the pitch between dots formed by ink. An object of the present invention is to provide an inkjet recording apparatus and an inkjet recording method capable of preventing the generation of streaks and the like.

[Means for Solving the Problems] Therefore, in the present invention, ink is ejected by utilizing thermal energy generated by applying an electric signal to an electrothermal converter provided in each of a plurality of ejection ports, In an inkjet recording method of forming dots on a recording medium by the ejected ink and performing recording, a waveform corresponding to a pitch between dots formed by ink ejected from adjacent ejection ports of the plurality of ejection ports And
By storing the waveform of the electric signal applied to the electrothermal converter provided in the corresponding discharge port, and applying the stored electric signal of the waveform to the corresponding electrothermal converter, It is characterized in that an amount of ink corresponding to the waveform is ejected from the corresponding ejection port to perform recording.

Further, it has a plurality of discharge ports and an electrothermal converter provided at each of the plurality of discharge ports, and utilizes thermal energy generated by applying an electric signal to the electrothermal converter. In an inkjet recording apparatus that ejects ink and forms dots on a recording medium by the ejected ink to perform recording, between dots formed by ink ejected from adjacent ejection ports of the plurality of ejection ports Storage means for storing a waveform of the electric signal applied to the electrothermal converters arranged at the corresponding ejection ports, the storage means having a waveform corresponding to the pitch, and an electric waveform having the waveform stored in the storage means. It is characterized by further comprising drive means for applying a signal to the corresponding electric converter to eject an amount of ink corresponding to the waveform from the corresponding ejection port to perform recording.

[Operation] According to the above configuration, an electric signal having a waveform corresponding to the pitch between dots formed by the ink ejected from the adjacent ejection ports of the plurality of ejection ports is applied to the electrothermal converter, and As a result, it is possible to perform recording by ejecting an amount of ink according to the applied waveform. Therefore, for example, when the pitch between the dots is large and the overlapping of those dots is small, the amount of ejected ink is large. It is possible to increase the size of the dots formed as described above and to cause dot overlap.

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

FIG. 1 is a perspective view showing an example of an ink jet recording apparatus applied to the present invention. A recording head 84 shown in FIG. 1 is composed of four recording heads corresponding to cyan, magenta, yellow and black, respectively. The recording head has 256 ejection ports arranged in the paper feeding direction (sub-scanning method). Further, the recording head is provided with electrothermal converters corresponding to the respective ejection ports, and ink is ejected by the thermal energy generated by the electrothermal converters. Recording head
A carriage 79 carrying 84 is slidably engaged with a guide shaft 83, and a belt 87 driven by a carriage motor 85.
And part of it. As a result, the recording head 84 can move in the main scanning direction along the guide axis, and ink is ejected in accordance with this movement to perform recording.

Further, the paper feed roller 86 is rotationally driven by the paper feed motor 50, whereby the recording paper p is fed in the direction of arrow f in the figure. At this time, the recording surface of the recording paper p is formed at a position facing the ejection port of the recording head 84 by the paper feed roller 86 and the transport roller 78 disposed below the roller 86.

2 (A) and 2 (B) are conceptual diagrams for explaining the operation of the present invention, and show the arrangement of ink dots that are printed on the recording paper. In these figures and FIG. 3 and subsequent figures, only the recording head corresponding to one kind of ink of the ink jet recording head 84 shown in FIG. 1 will be referred to. In addition, in FIGS. 2A and 2B, not all the dots corresponding to the 256 ejection ports of the recording head are shown, but only the dots corresponding to the five ejection ports are shown.
That is, in these figures, the dots i-2, i-1, i, i + 1, i
Corresponding to +2, the result is shown in which five ejection ports arranged in the horizontal direction in the drawing form dots in three rows while sequentially moving in the arrow direction in the drawing.

FIG. 2 (A) is a diagram showing the result of recording by the conventional method. Adjacent dots do not overlap at the boundary indicated by the arrow L _W in the figure, and this portion appears as white streaks in the entire image. That is, normally, in image recording using ink dots, the entire area of one pixel is filled with dots in order to obtain a predetermined reflection density. For example, in the case of a square pixel, dot size inevitably causes dot overlap because the dot diameter is set to be a circumscribing circle of the square. The white streaks as described above may occur.

The non-overlapping portion indicated by the arrow L _W in the drawing is caused by the pixel pitch b between the ejection openings corresponding to i-1 and i becoming large due to the above-described variation. As the pitch b increases, the pitch a or c decreases, for example.

FIG. 2B is a diagram showing a recording result to which the present invention is applied. In order to compensate for the size of the pitch b, that is, the amount of spread of the pitch, the diameters of the recording dots i-1 and i are increased so that the overlapping is prevented. Is what causes it. In order to control the diameter of the recording dot, the energy of the applied pulse applied to the electrothermal converter described above with reference to FIG. 1, that is, at least one of the pulse voltage and the pulse width may be changed.

FIG. 3 shows the relationship between the width of the applied pulse and the diameter of the recorded dots. By the way, in the example shown in FIG. 2B, an applied pulse having a pulse width of 7 (μsec) is applied to the recording dots i-2, i + 1 and i + 2, and an applied pulse having a pulse width of 9 (μsec) is applied to the dots i-1 and i.

In the above example, an example in which the recording dot diameter is increased in order to correct the white streak has been shown, but the pitch between adjacent recording dots is small, or the dot diameter is too large in the above control, and the ink overlaps. The area becomes large, and as a result, the density of this area increases and black streaks may occur.
In this case, contrary to the above example, it is necessary to reduce the recording dot diameter to reduce the area of the overlapping portion.

As described above, in order to eliminate the white stripes or the black stripes, not only the recording dot diameter is simply increased or decreased, but also the appropriate recording dot diameter must be selected.

Therefore, in the present invention, the pitch (relative distance) between the recording dots recorded in advance with a constant applied energy is obtained, and the diameter of the recording dot, that is, the energy of the applied pulse is set based on this pitch.

For example, the condition for obtaining the most uniform image in the example shown in FIG. 2 is that the dot diameter is 92 in order from dot i-2 to i + 2.
(Μm), 105 (μm), 100 (μm), 88 (μm), 92 (μ
m), and the pulse width for realizing this dot diameter is 7 (μsec), 9 (μsec), 8 (μsec), 6 (μsec), 7 (μ
sec). That is, the energy of the applied pulse may be determined according to the pitches a, b, c and d between the dots shown in FIG. When measuring the pitch between dots, at both ends of the dot array, only the pitch between adjacent dots on one side is measured.

FIG. 4 is a circuit block diagram of a recording head drive circuit according to an embodiment of the present invention. In the figure, 84 is the above-mentioned recording head corresponding to one type of ink,
84 is the electrothermal converter 84A, and these electrothermal converters 84A
Each of them has a counter 84B and a shift register 84C for giving an applied pulse based on the recording data. 10 is a pulse width memory described later, 11 is a buffer for temporarily storing recording data, 12 is a buffer 11 and pulse width memory 10
It is an AND gate that receives the output from. It should be noted that although the electrothermal converters 84A are provided corresponding to the number of 256 discharge ports, only five are shown in the drawing.

The pulse width memory 10 records in advance with a constant applied pulse, and in this recording result, the pitch (relative distance) between each recording dot is directly measured by using a microscope or the like. The applied pulse width based on the relationship shown is stored for each ejection port.

FIG. 6 is a diagram showing the relationship between the dot distance and the applied pulse width for obtaining the best image obtained by experiments in advance. In other words, from this relationship, the applied pulse width is calculated for each ejection port from the respective distances between the dot formed by this ejection port and the dots formed by two adjacent ejection ports, and the obtained pulse width is determined by the pulse width of the ROM or the like. The memory 10 is stored in association with each ejection port.

As described above, in the configuration shown in FIG. 4, the recording data supplied from the host device or the like is temporarily stored in the buffer 11 and is synchronized with the read clock, and the pulse corresponding to each of the ejection ports, that is, the electrothermal converters 84A. The width data and the recording data are output from the pulse width memory 10 and the buffer 11, respectively, and these are input to the AND gate 12. Here, only when the recording data is "1", 4-bit pulse width data is output and input to the shift register 84C. From the shift register 84C, pulse width data corresponding to five electrothermal converters are simultaneously output at a predetermined timing, and the counter 84B counts these data in synchronization with the clock in accordance with the length of the electrothermal converter. It is applied to the converter 84A.

In the above embodiment, the relative distance between the recording dots is directly measured, but the reflection density that changes depending on the relative distance between the dots is optically measured, and the energy of the applied pulse is determined according to this result. You may do it. That is, the recorded image is 400d, which is equal to the ejection port pitch.
Read with a CCD having a density of pi, and determine the applied pulse width with reference to the relationship in FIG. 7 based on the optical density obtained at the boundary between the recording dots. FIG. 7 is a diagram showing the same relationship as FIG. 6, and shows the relationship of the applied pulse width according to the optical density of the boundary portion instead of the relative distance.

The pulse width determined as described above is stored in the pulse width memory 10 shown in FIG. 4 corresponding to each ejection port, and recording is performed based on this.

FIG. 5 is a circuit block diagram of a recording head drive circuit according to another embodiment of the present invention. What is different from the circuit shown in FIG. 4 is that an address counter is used instead of the pulse width memory.
13, a pulse density designation ROM 14 and a pulse waveform ROM 15, and further has a two-row counter 84B 'and an OR gate 84d for taking an output of either of the two-row counters. This circuit produces an applied pulse having the waveform shown in FIG.

FIG. 8 is a diagram showing the relationship of the pulse waveforms according to the relative distance between dots. While the pulse width is changed in the above two embodiments, the pulse waveform is changed in this embodiment. The applied energy for ejection is made more diverse and finer, and the size of the recording dot can be finely controlled.

In the figure, in the pulse waveform designation ROM 14, in order to designate the pulse waveform obtained based on the relationship shown in FIG. 8, the address of the pulse waveform ROM 15 for storing this pulse waveform data is stored for each ejection port. .

The waveform data output from the pulse waveform ROM15 is the 4th
In the same manner as described above in the figure, the AND gate 12 is passed according to the recording data from the buffer 11 to shift register 84C.
To enter. The data in the shift register 84C is counted by the clock PC ₁ or PC ₂ in the two-column counter 84B 'and is applied as a pulse to the electrothermal converter 84A via the OR gate 84d.

In each of the above-described embodiments, the case where the present invention is applied to the serial type inkjet recording device has been described, but the present invention is also applied to the line type recording device in which the ejection port array is arranged corresponding to the width of the recording paper. The invention is applicable.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, an electric signal having a waveform corresponding to a pitch between dots formed by ink ejected from adjacent ejection ports of a plurality of ejection ports is generated. By applying to the electrothermal converter, and by doing this, it is possible to eject and print an amount of ink according to the applied waveform, so for example the pitch between the dots is large and the overlap of these dots is small. In this case, it is possible to increase the amount of ejected ink to increase the size of the formed dots and to cause dot overlap.

As a result, even if the position of the dot to be recorded is displaced, this can be compensated by making the dot diameter variable, whereby streaks and unevenness in the recorded image can be prevented, and high image quality can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an ink jet recording apparatus to which the present invention is applied, and FIGS. 2 (A) and 2 (B) are conceptual views showing a recording head array for explaining the operation according to an embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the pulse width applied to the electrothermal converter and the recording dot diameter, and FIG. 4 is a circuit block diagram showing the recording head drive circuit according to one embodiment of the present invention. FIG. 5 is a circuit block diagram showing a recording head drive circuit according to another embodiment of the present invention, and FIG. 6 is a table diagram showing the relationship between dot distance and applied pulse width according to one embodiment of the present invention. FIG. 7 is a table showing the relationship between the optical density between dots and the applied pulse width according to another embodiment of the present invention, and FIG. 8 shows the distance between dots and the applied pulse waveform according to still another embodiment of the present invention. It is a table showing the relationship of. 10 …… pulse width memory, 11 …… buffer, 12 …… and gate, 13 …… address counter, 14 …… pulse waveform specification ROM, 15 …… pulse waveform ROM, 84 …… recording head, 84A
...... Electric heat converter, 84B, 84B '…… Counter, 84C …… Shift register, 84d …… OR gate.

Claims (6)

(57) [Claims] 1. An ink is ejected by utilizing thermal energy generated by applying an electric signal to an electrothermal converter provided in each of a plurality of ejection ports, and the ejected ink ejects the ink onto a recording medium. In an inkjet recording method for forming dots to perform recording, a waveform corresponding to a pitch between dots formed by ink ejected from adjacent ejection ports of the plurality of ejection ports, By storing the waveform of the electric signal applied to the electrothermal converter disposed in the, and applying the stored electric signal of the waveform to the corresponding electrothermal converter, the amount according to the waveform. The ink jet recording method, wherein the ink is ejected from the corresponding ejection port to perform recording. 2. The ink jet recording method according to claim 1, wherein the stored waveform is a pulse width of the electric signal. 3. The ink jet recording method according to claim 1, wherein the stored waveform has a pulse width when the electric signal is composed of a plurality of pulses. 4. A plurality of discharge ports and an electrothermal converter provided in each of the plurality of discharge ports, wherein thermal energy generated by applying an electric signal to the electrothermal converter is applied. An ink jet recording apparatus that ejects ink by utilizing the ejected ink to form dots on a recording medium for recording, and is formed by ink ejected from adjacent ejection ports of the plurality of ejection ports. Storage means for storing the waveform of the electric signal applied to the corresponding electrothermal converter arranged at the corresponding ejection port, the storage means having a waveform corresponding to the pitch between the dots; A drive unit for applying a waveform electric signal to the corresponding electric conversion body to eject an amount of ink corresponding to the waveform from a corresponding ejection port to perform recording. That the ink jet recording apparatus. 5. The ink jet recording apparatus according to claim 4, wherein the waveform stored in the storage means is a pulse width of the electric signal. 6. The ink jet recording apparatus according to claim 4, wherein the waveform stored in the storage means has respective pulse widths when the electric signal is composed of a plurality of pulses.