JPH02235757A - Ink jet recording apparatus and method thereof - Google Patents

Abstract

PURPOSE:To make the diameter of a dot to be recorded variable by changing the energy of the electric pulse applied corresponding to the pitch between formed dots. CONSTITUTION:A pulse width memory 10 preliminarily performs recording on the basis of a definite applied pulse to measure the pitch between respective recording dots in this recording result and stores this measured pitch and the width of the applied pulse at every emitting orifice. Recording data is once stored in a buffer 11 and the pulse width data and recording data respectively correspond to emitting orifices, that is, electrothermal converters 84A are respectively outputted to the pulse width memory 10 and the buffer 11 in synchronous relation to a read clock and inputted to an AND gate. The pulse width data corresponding to five electrothermal converters are outputted all at once from a shift register 84C in predetermined timing and these data are counted corresponding to the lengths thereof in synchronous relation to a clock by counters 84B to be applied to the electrothermal converters 84A.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inkjet recording device used in printers, facsimile machines, copying machines, etc., and a recording method for the device, and more specifically, the present invention relates to an inkjet recording device used in printers, facsimile machines, copying machines, etc., and a recording method of the device. The present invention relates to an inkjet recording device using an electrothermal transducer and a recording method using the device.

[Prior Art] The recording head of an apparatus using this type of electrothermal transducer can be manufactured using a process similar to the semiconductor device manufacturing process, which has recently been significantly developed. It has the advantage that it is possible to use multiple nozzles and to perform high-definition recording.

Moreover, the above-mentioned rigorous manufacturing process enables mass production and cost reduction, and disposable recording heads are also becoming a reality.

[Problem to be Solved by the Invention] Incidentally, although the above-mentioned recording head manufacturing process has a high degree of reproducibility in its shape, etc., due to the multi-nozzle structure, there is some difference between each of the many ejection ports. Differences in shape may occur. Furthermore, in the case of disposable recording heads, there may be individual differences in manufacturing between the recording heads.

In addition, by increasing the density of the ejection ports, the distance M between the ejection ports
The ratio of the distance between the ejection opening and the recording medium facing it to the pitch (pitch) has become larger than before, and as a result, variations in the ejection opening, such as variations in the pitch of the ejection opening and the direction of ink ejection, are reduced. This is noticeable as variations in pixels.

Furthermore, the performance of the electrothermal converter installed at each outlet,
There may also be variations in the shape of the ink chamber or the like that communicates with the ejection port.

As explained above, as a result of the slight variations in each ejection port, the arrangement of dots formed by ejecting ink becomes non-uniform, and this non-uniform arrangement of dots eventually causes streaks etc. in the formed image. However, there were cases where the image quality deteriorated.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to measure the relative distance between each dot in advance, and set the energy applied to the ejection port based on the relative distance. An object of the present invention is to provide an inkjet recording device and an inkjet recording method that make it possible to prevent the occurrence of streaks and the like that degrade image quality during recording.

[Means for Solving the Problems] To this end, the present invention includes a plurality of discharge ports and an electrothermal converter disposed in each of the plurality of discharge ports, and applies an electric pulse to the electrothermal converter. In the recording method of an inkjet recording device, in which ink is ejected using the thermal energy generated by the ejected ink, and dots are formed on a recording medium using the ejected ink, an ejection port array consisting of a plurality of ejection ports is used. A dot array corresponding to the I The energy to be applied to the electric pulse for each electrothermal transducer corresponding to the discharge port is determined by referring to the relationship with the amount indicating the predetermined pitch, and the electric pulse of the determined applied energy is It is characterized in that recording is performed by applying voltage to an electrothermal transducer.

[Function] According to the above configuration, it is possible to change the energy of the applied electric pulse depending on the pitch between the formed dots, thereby making it possible to make the diameter of the recorded dots variable.

[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 inkjet recording apparatus applicable to the present invention, and the recording head 84 shown in the figure is a cyan. Magenta, yellow. It consists of four recording heads corresponding to each color of black, and each recording head has 256 ejection ports arranged in the paper feeding direction (sub-scanning method). Further, this recording head is provided with an electrothermal converter corresponding to each ejection port, and ink is ejected using thermal energy generated by the electrothermal converter. A carriage 79 carrying a recording head 84 is slidably engaged with a guide shaft 83 and is partially coupled to a belt 87 driven by a carriage motor 85 . This allows the recording head 84 to move in the main scanning direction along the guide glaze, and as it moves, ink is ejected to perform recording. Further, the paper feed roller 86 is rotationally driven by the paper feed motor 5G, whereby the recording paper p is fed in the direction of the arrow f in the figure. At this time, a recording surface of the recording paper p is formed at a position facing the ejection opening of the recording head 84 by the paper feed roller 8B and the conveyance roller 78 disposed below the roller 86.

FIGS. 2(^) and 2(B) are conceptual diagrams for explaining the operation of the present invention, and show the arrangement of ink dots printed on recording paper. In these figures and from figure 3 onwards,
Only a recording head compatible with one type of ink of the inkjet recording head 84 shown in FIG. 1 will be mentioned.
Furthermore, in FIGS. 2(^) and (8), all dots corresponding to the 256 ejection ports of the recording head are not shown, but only dots corresponding to 5 ejection ports are shown. That is, in these figures, dots i-2, i-1, i, i
Corresponding to +l, i◆2, the results are shown in which five discharge ports arranged in the horizontal direction in the figure form three rows of dots while sequentially moving in the direction of the arrow in the figure. FIG. 2(A) is a diagram showing the result of recording using the conventional method. Adjacent dots do not overlap at the boundary indicated by the arrow Lw in the figure, and this area appears as a white stripe 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, the dot diameter is set to a size that corresponds to the circumcircle of the square, so dots inevitably overlap, and without this overlap, the desired density cannot be obtained and as described above. White streaks may appear. The non-overlapping portion indicated by the arrow Lw in the figure is generated due to the above-mentioned variation in at least one of the ejection ports corresponding to i-1 and i, and the pixel bit b therebetween becomes large. As this pitch b increases, for example, pitch a or C decreases. Figure 2 (
B) is a diagram showing the recording results obtained by applying the present invention, in which the diameters of recording dots i-1 and i are increased to cause overlapping in order to compensate for the increase in the size of the pitch b, that is, the pitch. be. In order to control the diameter of the recording dots, it is sufficient to change the energy of the applied pulse applied to the electrothermal transducer described above in FIG. 1, that is, at least one of the pulse voltage and the pulse width.

Figure 3 shows the relationship between the width of the applied pulse and the diameter of the recorded dot. Incidentally, in the example shown in FIG. 2(B), the recorded dots i-2. i+1. i+2 with pulse width 7 (μsec)
, dot i-1, i has a pulse width of 9 (μsec)
An application pulse of .

The above example shows an example in which the recording dot diameter is increased to correct white streaks, but if the pitch between adjacent recording dots is small or the dot diameter is increased too much using the above control, the ink may overlap. The area becomes larger, 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.

In this way, to eliminate white lines or black lines,
Rather than simply increasing or decreasing the recording dot diameter, an appropriate recording dot diameter must be selected.

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

For example, in the example shown in Figure 2, the conditions for obtaining the most uniform image are that the dot diameter is 92 mm in order from dot i-2 to i◆2.
(μm). 105(μ■＞, 100(μm), 88(
μm), 92 (μI1), and the pulse widths to achieve this dot diameter are 7 (μsec), 9 (μs
ec), 5 (μsec), 6 (psec),
7 (μsec). 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. Note that when measuring the pitch between dots, only the pitch between adjacent dots on one side is measured at both ends of the dot array.

FIG. 4 shows 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 l types of ink, and the recording head 84 applies pulses to the electrothermal transducer 84A and to each of these electrothermal transducers 84^ based on recording data. It has a counter 84 and a shift register 84 for inputting. 10 is a pulse width memory which will be described later, 11 is a buffer for temporarily storing recording data, and 12 is an AND gate which manually outputs the output from the buffer 11 and the pulse width memory 10. Note that the electrothermal converters 84^ are provided corresponding to the number of discharge ports, which is 256, but only five are shown in the figure.

The pulse width memory IO performs recording in advance with a constant applied pulse, and in this recording result, the pitch between each recording dot (
The relative distance N) is directly measured using a microscope or the like, and the applied pulse width based on the measured pitch and the relationship shown in FIG. 6 is stored for each ejection port.

FIG. 6 is a diagram showing the relationship between the inter-dot distance and the applied pulse width for obtaining the best image, which was determined in advance through experiments. That is, from this relationship, the applied pulse width is calculated for each ejection port from the distance between the dot created by this ejection port and the dots created by two adjacent ejection ports, and this determined value is calculated as the pulse width determined by IIOM, etc. It is stored in the memory IO in correspondence with each discharge port.

As described above, in the configuration shown in FIG. 4, the recording data supplied from the host device etc. is temporarily stored in the buffer 11, and is sent to each of the discharge ports, that is, the electrothermal converters 84^, in synchronization with the readout clock. Pulse width data and recording data are output from pulse width memory IO and buffer 11, respectively, and are input to AND gate l2. Here, only when the recording data is "cross", 4-bit panorez width data is output and manually input to the shift register 84G. The shift register 84G outputs pulse width data corresponding to the five electrothermal converters all at once at a predetermined timing, and these data are counted according to their lengths in synchronization with the clock by the counter 84B. is applied to the converter 84A. Note that in the above embodiment, the relative distance between recording dots is directly measured, but the reflection density, which changes depending on the relative distance between dots, is optically measured, and the energy of the applied pulse is determined according to this result. You can do it like this. That is, the recorded image is transferred to a CCD having a density of 400 dpi, which is equal to the ejection port pitch.
Based on the optical density obtained at the boundary between each recording dot, the applied pulse width is determined with reference to the relationship shown in FIG.

FIG. 7 is a diagram showing the same relationship as FIG. 6, and instead of the relative distance, the relationship of the applied pulse width according to the optical density of the boundary portion is shown.

The pulse width determined as described above is stored in the pulse width memory 10 shown in FIG. 4 in correspondence with 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, and the difference from the circuit shown in FIG. 4 is that an address counter 1 is used instead of a pulse width memory.
3. Pulse density specification ROM 14, pulse waveform ROM 15
Furthermore, it has two columns of counters 84B' and an OR gate 8 for taking the output of either of the two columns of counters.
4d. This circuit generates an applied pulse having the waveform shown in FIG.

FIG. 8 is a diagram showing the relationship between pulse waveforms depending on the relative distance between dots. In the above two embodiments, the pulse width was changed, but in this embodiment, by changing the pulse waveform, The applied energy for ejection is made more diverse and fine-grained, and the size of the recorded dots can be precisely controlled.

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

The waveform data outputted from the pulse waveform ROM15 passes through the AND gate 12 in accordance with the recorded data from the buffer yll, and is manually input to the shift register 84G, as described above with reference to FIG. The data in the shift register 84C is input to the clock PCI in a two-column counter 84B'.
Or counted by PC, or gate 84d
is applied as a pulse to the electrothermal transducer 84^ through. In each of the above-mentioned embodiments, the present invention is applied to a serial type inkjet recording device, but the present invention can also be applied to a line type recording device in which a row of ejection ports is arranged corresponding to the width of recording paper. The invention is. Applicable.

[Effects of the Invention] As is clear from the above description, according to the present invention, the energy of the applied electric pulse is changed according to the pitch between the formed dots, thereby making it possible to vary the diameter of the recorded dots. It becomes possible to do so.

As a result, even if the position of the recorded dots shifts,
This can be compensated for by making the dot diameter variable, thereby preventing streaks, unevenness, etc. in the recorded image.
High image quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of an inkjet recording apparatus to which the present invention is applied, and FIGS. 2 (^) and (B) are conceptual diagrams showing a recording head arrangement for explaining the operation according to an embodiment of the present invention. 3 is a diagram showing the relationship between the pulse width applied to the electrothermal transducer and the recording dot diameter. FIG. 4 is a circuit block diagram showing a recording head drive circuit according to an 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; FIG. 6 is a table showing the relationship between dot distance and applied pulse width according to an embodiment of the present invention; FIG. 7 is a table showing the relationship between the inter-dot optical density and the applied pulse width according to another embodiment of the present invention, and FIG. 8 is a table showing the relationship between the inter-dot optical density and the applied pulse width according to still another embodiment of the present invention. FIG. lO...Pulse width memory, 11...Buffer, 12...And gate, 1 3-...Address counter, 14...Pulse waveform specification ROM, 15...Pulse waveform ROM, 5o Fig. 1 84... Recording head, 848... Electrothermal converter, 84B, 84B'... Counter, 84C...
Shift register, 84d...OR gate. i-2 i-1 i i+1 i+2 Figure 2 Figure 3 (μsec) Figure 6

Claims (1)

[Claims] 1) It has a plurality of discharge ports and an electrothermal converter disposed in each of the plurality of discharge ports, and is generated by applying an electric pulse to the electrothermal converter. In a recording method for an inkjet recording device that uses thermal energy to eject ink and forms dots on a recording medium using the ejected ink, the recording method is configured to correspond to the ejection port array consisting of the plurality of ejection ports in advance. A dot array is recorded by forming dots for each of the ejection ports, and an amount indicating the pitch between adjacent dots is determined for each dot in the recorded dot array, and the amount is determined in advance by the determined amount. Determine the energy to be applied to the electric pulse for each electrothermal transducer corresponding to the discharge port with reference to the relationship with the determined amount indicating the pitch, and apply the electric pulse of the determined applied energy to each corresponding one. A recording method for an inkjet recording apparatus, characterized in that the recording is performed by applying a voltage to the electrothermal transducer. 2) It has a plurality of discharge ports and an electrothermal converter disposed in each of the plurality of discharge ports, and utilizes thermal energy generated by applying an electric pulse to the electrothermal converter. In an inkjet recording device that performs recording by ejecting ink and forming dots on a recording medium using the ejected ink, a dot array corresponding to the ejection port array consisting of the plurality of ejection ports is created in advance for each ejection port. Recording is performed by forming dots, and for each dot in the recorded dot array, the amount indicating the pitch between adjacent dots is determined,
Storage means for storing applied energy to be applied to the electric pulse determined for each electrothermal transducer corresponding to the discharge port, with reference to a relationship between the determined amount and a predetermined amount indicating the pitch; An inkjet recording apparatus comprising: a drive means for causing the recording to be performed by applying an electric pulse of the applied energy stored in the storage means to the corresponding electrothermal transducer. 3) The inkjet recording apparatus or the recording method using the apparatus according to claim 1 or 2, wherein the amount indicating the pitch is a directly measured pitch. 4) The ink jet recording apparatus or the recording method using the apparatus according to claim 1 or 2, wherein the amount indicating the pitch is an optical density between the adjacent dots. 5) What corresponds in relation to the predetermined quantity indicating the pitch is the width of the electric pulse at the applied energy.
The inkjet recording device or the recording method using the device according to any one of the above. 6) The inkjet recording apparatus according to any one of claims 1 to 4, wherein what corresponds in relation to the predetermined amount indicating the pitch is the waveform of the electric pulse at the applied energy. Or a recording method using the device.