JPH01141057A - Method and device for ink jet recording - Google Patents

Abstract

PURPOSE:To easily reproduce a multi-gradation recording image with the effective prevention of resolving power deterioration and complicated signal processing, by a method wherein, the amount of an energy to be applied to an ink unit area to be a printing object is varied according to a density level of objective image information, whereby a printing dot of a diameter dimension according to the density level of object image information is formed. CONSTITUTION:A heat signal and an electrostatic signal are applied to a unit area of an ink 3 to be a printing object, and an elapsed time from the start of a heat signal applying timing to the start of a electrostatic signal applying timing is varied according to a density level of object image information. In this manner, the amount of a heat energy to be applied to the unit area of the ink 3 until the start of electrostatic signal application is made according to the density level of an objective image information, the range reaching a critical flying condition is made corresponding to the density level in the unit area of the ink 3, and the corresponding part is raised toward a recording sheet 5 by an induction force of an electrostatic field according to the electrostatic signal. Then, the top of the raised ink column comes into contact with the recording sheet 5 and adheres thereto, whereby a printing dot having a diameter dimension according to the density level of object image information is formed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inkjet recording method and an apparatus thereof, and in particular is based on a type in which ink is ejected by the cooperative action of thermal energy and electrostatic energy. The present invention relates to an inkjet recording method and apparatus capable of recording gradation images.

[Prior art 1] A conventional inkjet recording device has a number of ink ejection devices that seal ink, and ejection ports (
It is known that the ink ejection device is provided with a plurality of orifices, respectively, and a pressure pulse is appropriately applied to the ink ejection device to eject ink from the ejection opening.

In this type, it is difficult to downsize the ink ejection device because it is necessary to maintain a large volume ratio between the ejection port and the ink ejection device in order to maintain the ink ejection operation from the ejection port. However, the pitch between the ejection ports has to be increased to some extent, which makes it impossible to set a high image recording density. Therefore, there is a problem that the recording speed inevitably decreases.

As a means to solve these problems, magnetic ink is placed near the magnetic electrode array, and the ink bulge caused by the magnetic field is used to form an ink ejection state corresponding to the image @ degree, and the magnetic ink is recorded using an electrostatic field. The so-called magnetic inkjet recording method in which the ink is ejected toward the sheet side
69469), a parallel slit-shaped ink reservoir in which an electrode array is arranged is filled with ink, and the ink is applied according to the electric field pattern formed between the electrodes and the electrode array that face each other via the recording sheet. The so-called plane scanning type inkjet recording method (Japanese Unexamined Patent Application Publication No. 1983-1983)
-37163 Publication), or by applying thermal energy to the ink, the ink is rapidly heated to cause film surface boiling, and bubbles are created within the ejection port (orifice).
A so-called thermal bubble jet recording method (Japanese Unexamined Patent Publication No. 161664/1984) has been proposed in which ink is ejected from an ejection port by increasing the pressure caused by rapid growth of the ink.

What is different about each of the conventional inkjet recording methods mentioned above?
In either case, not only can the density of the recorded image be increased, but also nine-speed recording that enables electronic scanning can be performed.

[Problems to be Solved by the Invention] However, in the magnetic inkjet recording method described above, since it is necessary to use ink mixed with magnetic powder, the ink inevitably becomes black. A problem arises in that overprinting ink to obtain a color image requires rotation. In addition, in the above-mentioned plane scanning inkjet recording method, ink clogging can be improved by eliminating the need for a minute orifice, but a high voltage must be applied to make the ink fly. In order to prevent voltage leakage between adjacent or nearby electrodes, the arrangement pitch of the electrodes in the electrode array cannot be unnecessarily narrowed, which is not preferable in terms of achieving high density. Furthermore, in the thermal bubble jet recording method described above, it is necessary to rapidly heat the heating resistor to raise the temperature in order to cause film surface boiling. There is a problem in that the heat-generating resistor protective layer provided thereon is more likely to be thermally degraded.

In order to solve such problems, the inventors of the present invention applied a heat signal according to image information using a heating resistor array or the like to a unit area of ink filled in a slit-shaped ink chamber of the head main body, for example. , an electrostatic signal is applied to the ink in synchronization with the application timing of this thermal signal, and the unit area of the heated ink is caused to fly toward the recording sheet side by the attractive force of the electrostatic field based on this electrostatic signal. Twelve thermostatic inkjet recording methods have already been proposed (Japanese Patent Application No. 67301/1982).

According to this type, there is no need to use magnetic ink as in the magnetic inkjet recording method, and therefore it is not only possible to easily realize coloring based on overprinting of ink, but also to realize so-called flat surface printing. Unlike the scanning inkjet recording method, it is no longer necessary to fly the ink using only an electrostatic field, and because there is no need to increase the strength of the electrostatic field to an extremely large extent, it is possible to effectively utilize voltage leaks between the electrodes that provide thermal signals to the ink. Moreover, since there is no need to make the ink fly using only a thermal signal as in the so-called bubble jet recording method, the thermal energy can be suppressed to some extent, and thermal deterioration of the ink can be effectively prevented. Therefore, it is possible to perform high-speed, high-density recording while effectively preventing the drawbacks of conventional methods.

By the way, in order to obtain a multi-gradation recorded image in such a thermostatic inkjet recording device, one pixel is subdivided into multiple dot matrices, and the number of dots printed for each pixel unit is increased or decreased as appropriate. The so-called area gradation method, which expresses shading, is usually used.

However, in grayscale display using such an area modulation method, since one pixel is made up of multiple dots, not only does the resolution inevitably decrease, but also signal processing is required for each dot that makes up one pixel. A problem arises in that the signal processing becomes unnecessarily complicated.

[Means for solving the illumination point] In order to solve such problems, the inventors of the present invention have determined that the size of a recording pixel is determined by the ink adhesion R, and that the ink adhesion radius is The inventors discovered that this corresponds to the time difference between the application start timings of the thermal signal and the electrostatic signal, and devised the present invention which reproduces recorded pixels with medium dots according to the density level of image information. It was.

That is, the first invention applies a thermal signal according to image information to the intermediate region of the corresponding ink, and also applies an electrostatic signal to the ink in synchronization with the application timing of the thermal signal, and this electrostatic signal When a unit area of ink to which a thermal signal has been applied is caused to fly toward the recording sheet that is placed facing the ink by the attractive force of an electrostatic field formed based on the ink, the timing of starting applying the thermal signal to the ink and the electrostatic signal This is an inkjet recording method in which the elapsed time from the application start timing is made variable according to the density level of image information.

Further, a second invention is an inkjet i-recording apparatus that realizes the first invention, and as shown in FIG. 1, a head main body 1 having an ink chamber 2 in which an ink discharge W2a is formed; Ink 3 filled in the ink discharge section 2a
a thermal signal applying means 4 for applying a thermal signal according to image information to a unit area of the ink 3, and a thermal signal applying means 4 for applying a thermal signal according to image information to a unit area of the ink 3 to form an electrostatic field directed from the surface of the ink 3 toward the side of the recording sheet 5 disposed opposite to the surface of the ink 3. an electrostatic signal applying means 6 for applying an electrostatic signal in synchronization with the application timing of the thermal signal; The thermal signal applying means 4 and the electrostatic signal applying means 6 are actuated based on the timing set by the timing controlling means 7, and the electrostatic signal from the electrostatic signal applying means 6 is controlled. A unit area of the ink 3 heated by the attractive force of an electrostatic field formed based on the above-mentioned No. 1 is made to fly toward the recording sheet 5 side.

In such technical means, the head body 1 as an ink storage member has an ink chamber 2 in which ink 3 is stored, and an ink discharge space serving as a storage space for ink to be flown to the exit side of the ink chamber 2. Any suitable material may be selected as long as it has the portion 2a. In this case,
The ink ejection section 2a may be a through hole depending on the pixel density, or may be a slit. Also,
The shape of the ink chamber 2 may be changed as appropriate, but from the viewpoint of maintaining good ink supply performance, the gap in the depth direction of the ink discharge section 2a may be set short, or the shape of the ink discharge section 2a may be changed. It is preferable to reduce the flow path resistance of the ink reservoir portion leading to the ink reservoir.

Further, as the thermal signal applying means 4, a heating element array formed by disposing heating elements such as heating resistors may be used, or radiation according to image information is applied to a portion of the radiation absorbing member corresponding to the pixel density. Alternatively, a part of the head body 1 may be made of an organic resistive film, and a portion of the organic resistive film that corresponds to the pixel density may be directly heated to generate a heat generating part. You can also use it as Furthermore, the formation position of each of the heat generating parts may be a wall part adjacent to the ink ejection opening of the head main body 1, or a wall part facing the ink ejection opening. At this time, when forming the heat generating part on the wall adjacent to the ink ejection opening, it is preferable to arrange the heat generating part close to the end of the head main body 1 in order to improve the heating efficiency of the surface of the ink 3. In addition, regarding the configuration of the control unit of the heat signal application means 40, the printing target is designed to specify the heat generating part to be printed, and to apply a heat signal so strong that the 30 unit area of ink corresponding to the heat generating part to be printed reaches a critical flying state. It is necessary to design the target heat generating part to be heated and driven.

Furthermore, when heating and driving the heat-generating portion to be printed, the entire line for one line may be driven at once, or may be driven in a time-division manner.

Furthermore, the design of the electrostatic signal applying means 6 may be changed as appropriate as long as it is capable of applying an electrostatic signal to the ink 3; Although the strength, pulse width, etc. vary depending on the ink 3 used, it is necessary to set them appropriately within a range that generates an attractive force that causes the heated ink 3 to fly toward the recording sheet 5 side.

Furthermore, with respect to the timing control means 7, the application timing of the thermal signal may be set constant and the application timing of the electrostatic signal may be set variably according to the density level of the image information, or vice versa. , the application timing of the electrostatic signal may be set constant, and the application timing of the thermal signal may be set variably according to the density level of the image information. The design may be changed as appropriate, such as by setting the timing variably according to the density level of the image information. Furthermore, the application timing of the thermal signal and the electrostatic signal by the timing control means 7 should be set within a range that allows the ink 3 to perform the flying operation reliably and to avoid a situation where the ink 3 is erroneously flown due to a bridging phenomenon or the like. It is necessary to consider.

In addition, the ink 3 to be used may be selected as appropriate as long as it reaches a flying state through the cooperation of a thermal signal and an electrostatic field according to the image information. It is preferable to select an ink that is optimal for temperature changes such as viscosity, surface tension, and electrical conductivity by comprehensively considering ink retention, ink supply, and ink flight performance in the ink discharge portion 2a. .

[Operation] According to the above-mentioned technical means, a thermal signal and an electrostatic signal are applied to a unit area of the ink 3 to be printed, but there is a difference between the starting point of the application timing of the thermal signal and the electrostatic signal. Since the elapsed time from the start of the application timing changes depending on the density level of the target image information, the thermal energy given to the unit area of the ink 3 by the time the electrostatic signal application starts is the most of the target image information. The range in which the ink 3 reaches a critical flight state in the unit area corresponds to the m degrees, and the corresponding part is attracted to the recording sheet 5 by the attractive force of the electrostatic field based on the electrostatic signal. As it rises to the side, the tip of the raised ink column contacts and adheres to the recording sheet 5, forming a printed dot with a diameter corresponding to the density level of the image information.

[Example] Hereinafter, the inkjet method and apparatus thereof according to the present invention will be explained to fMJ based on the example shown in the attached drawings.

Example 1 In FIG. 2, an inkjet recording apparatus includes a head main body 1 having a slit-shaped ink chamber 2, and the ink chamber 2.
A thermal signal applying means 4 applies a thermal signal to an ink unit area corresponding to the pixel density of the ink 3 accommodated in the ink ejection part 2a, and a thermal signal applying means 4 synchronizes with the application timing of the thermal signal of the thermal signal applying means 4. an electrostatic signal applying means 6 for applying an electrostatic signal to the ink 3, and a timing control means 7 for controlling the thermal signal application timing and the electrostatic signal application timing according to the density level of image information (see FIG. 4). ).

It is equipped with

In this embodiment, the head main body 1 includes a pair of insulating substrates 11 and 12 made of alumina ceramics or the like, which are spaced apart by a predetermined distance (approximately 50 to 100 μm) via a spacer member (not shown), and a resupply edge substrate 11. An ink chamber 2 filled with ink 3 is secured between the ink chambers 12 and the outlet side of the ink chamber 2 functions as an ink discharge section 2a. The ink 3 filled in the ink chamber 2 is an oil-based ink obtained by dispersing a pigment or dissolving a dye in an oil-based medium such as paraffin or olefin, and its physical properties are shown in FIG. In addition, it has a surface tension of 20 to 30 dyne/cIR1 at room temperature (e.g., 20°C), a volume resistivity of about 107 to 1011 Ωα, and a high temperature resistance when heated (e.g., at 150°C).
), the surface tension and volume resistivity are reduced by about one to two orders of magnitude.

Further, as shown in FIGS. 2 and 4, the thermal signal applying means 4 heats and drives the heating resistor array 20 according to the pixel density (for example, 8 dots/m) and the heating resistor array 20. It consists of a heating driver 25.

In this embodiment, the heating resistor array 20 has heating resistors 21 arranged for each pixel density, and each heating resistor 21 is made of, for example, a T a 2 N '770 film on the opening side of the ink ejection section 2a. It is formed in the shape of a closed mouth, and is disposed on one side of the insulating substrate 11 side corresponding to the ink discharge portion 2a of the slit-shaped ink chamber 2, and each heating resistor 21 has a large diameter. - A pair of current-carrying electrodes 22 are connected, and these heating resistors 21 and each current-carrying electrode 22 are connected to each other.
It is insulated and coated with an insulating layer 23 of a predetermined thickness made of 102 or the like. The heating driver 25 is a switching element that is connected to the current-carrying electrode 22 of each heating resistor 21 and turns on in response to print data while a heating timing signal (enable signal) Δ1, which will be described later, is input. 2
6 and energization for applying a predetermined heating voltage to the heating resistor 21 when each switching element 26 is turned on? lf source 27
It is made up of.

Furthermore, the electrostatic signal applying means 6 is provided on an insulating layer 23 covering one insulating substrate 11 of the head main body 1 and having a thickness of, for example, 1. A conductive layer 31 made of a metal layer of Cr/Cu/Cr on the order of oooA, and a roll-shaped electrostatic induction electrode 32 that is spaced a predetermined distance from the end surface of the head body 1 and also functions as a support surface for the recording sheet 5. Then, an electrostatic signal S is applied to the ink 3 to form an electrostatic field interposed between the conductive layer 31 and the electrostatic induction electrode 32 and directed from the surface of the ink 3 toward the electrostatic induction electrode 32 side. It is composed of an electrostatic driver 33. Then, the electrostatic driver 3
3 outputs an electrostatic control signal consisting of a predetermined induced voltage in response to an electrostatic timing signal A2 to be described later.

Furthermore, the timing control means 7 includes a data conversion circuit 41 that converts one line of serial multi-gradation image data DT into binary data of multiple cycles necessary for processing, and a data conversion circuit 41 that converts the converted data of this data conversion circuit 41. A buffer memory 42 temporarily stores data, a shift register 43 stores one line of data for each cycle from the rough memory 42, and a shift register 43 stores data for one line in each cycle from the rough memory 42. The heating timing signal (enable signal) AI is sent to the electrostatic driver 33 as the electrostatic timing signal A2.
is a motor timing signal A to a driver 34 of a stepping motor (not shown) that drives the electrostatic induction electrode 32.
A pulse generator 44 that outputs 3 is provided.

In this embodiment, the data conversion circuit 41, for example, as shown in FIG.
...Image data for n (2 bits each),
For example, rl 1.01, 10,00°10...
01J is converted into conversion data (3-bit configuration) divided into three periods. Further, as shown in FIG. 6, the heating timing signal A1 from the pulse generator 44 is generated with a predetermined pulse width T1 every three cycles C1 to C3 of the image data processing cycle for one line. It has become. On the other hand, the electrostatic timing signal A2 from the pulse generator 44 has a predetermined pulse width T.
2 (T2 <TI), the period C of this electrostatic timing signal A2 is set to be slightly shorter than the second period C2 of the heating timing signal A1, and each static The end point of the electric timing signal A2 is delayed by 1/4 pulse width from the end point of the heating timing signal A1 in the first cycle 01, and approximately coincides with the end point of the heating timing signal A1 in the second period C2. , furthermore,
The heating timing signal A1 is set to advance by 1/4 pulse width from the end point of the heating timing signal A1 in the third cycle 03. In this embodiment, the pulse width T1 of the heating timing signal A1 is set to 1.4 ms, and the pulse width T2 of the electrostatic timing signal A2 is set to 0.4 ms.

Next, the operation of the inkjet recording apparatus according to this embodiment will be explained.

Now, as shown in FIGS. 4 and 5, when the image data DT is input to the data conversion circuit 41, this data conversion circuit 41 converts it into converted data of 3-bit configuration. Then, this converted data is once stored in the buffer memory 42, and then sequentially stored in the shift register 43 starting from the converted data of the first cycle.

In this state, when the heating timing signal A1 is applied as an enable signal to the heating driver 25, as shown in FIG. 11″
) The switching element 26 of the heating driver 25 corresponding to
turns on, the heating control signal p1 is output, and the pixel of interest 3 is turned on in synchronization with the heating timing signal A1 of the second cycle 02.
, 5 (image data “10”)
The switching element 26 of No. 5 is turned on and the heating control signal p1 is output, and the switching element 26 of the pixel of interest 2. n (image data “01”
) The switching element 2 of the heating driver 25 corresponding to
6 is turned on and the heating control signal p1 is output. still,
Since the pixel of interest 4 corresponds to the image data "'o o", the heating control signal p1 is not output.On the other hand, when the electrostatic timing signal A2 is given to the electrostatic driver 33 at a predetermined timing, this An electrostatic control signal p2 is outputted from the electrostatic driver 33 in synchronization with .

As shown in FIG. 9, when the heating control signal p1 is applied to the corresponding heat generating resistor 21, a predetermined heat signal Q is applied from each heat generating resistor 21 to the corresponding unit area M of the ink 3. When the electrostatic control signal p2 is applied between the conductive layer 31 and the electrostatic induction electrode 32, a constant electrostatic signal S is applied to the ink 3. .

FIG. 7 shows the relative relationship between the application timings of the thermal signal Q and the electrostatic signal S during such an operation process.

That is, in the case of image data "11", FIG.
) As shown in (b), the elapsed time T from the start of application of the thermal signal Q to the start of application of the electrostatic signal S is 1.1 ms.
During this period, the surface temperature of the corresponding ink unit area M changes as shown by the solid line in FIG. The heating range is set as shown by W1 in FIG. In this state, the electrostatic signal S
When is applied, as shown by the dotted line in FIG. 9, the ink unit area M rises toward the recording sheet 5 side in the high temperature heating range W1 due to the attractive force of the electrostatic field based on the electrostatic signal S. The tip of the ink column 3a comes into contact with and adheres to the recording sheet 5, forming a printed dot D having a large diameter (100±8 μm in this embodiment) as shown in FIG.

In addition, in the case of image data “10′°, Fig. 7(a)
As shown in (C), the elapsed time T from the start of application of the thermal signal Q to the start of application of the electrostatic signal S is 1.0 ms, and during this time, the surface warming of the corresponding ink unit area M has started. The temperature changes as shown by the dashed line in FIG. 8, and the high temperature heating range of the ink 3 exceeding the critical flight condition temperature to is set as shown by W2 in FIG. In this state, when the electrostatic signal S is applied, as shown by the dashed line in FIG. The tip of the raised inline pillar 3a is raised toward the sheet 5 side and comes into contact with and adheres to the recording sheet 5, forming a printed dot D with a medium diameter (60±6 μm in this example) as shown in FIG. .

Furthermore, in the case of image data "'01", as shown in FIG. 7(a)
As shown in (d), the elapsed time T from the start of application of the thermal signal Q to the start of application of the electrostatic signal S is 0.9 ms, and during this time the surface temperature of the corresponding ink unit area M is 8. The temperature changes as shown by the two-dot chain line in the figure, and the high temperature heating range of the ink 3 exceeding the critical flight condition temperature to is set as shown by W3 in FIG. In this state, when the electrostatic signal S is applied, the ink unit area 14M is moved to the high temperature heating range by the attractive force of the electrostatic field based on the electrostatic signal S, as shown by the two-dot chain line in FIG. At W3, the tip of the raised ink pad 3a is raised toward the recording sheet 5 side and adheres to the recording sheet 5, forming a printed dot D with a small diameter (24±5 μTrL in this example) as shown in FIG.
is formed.

Furthermore, regarding the image data "OO", since the thermal signal Q is not applied to the ink middle region M, a high temperature heating range is not formed in the ink unit region M, and even if the electrostatic signal S is applied to the ink 3. Even so, the ink 3 does not rise toward the recording sheet 5 side, and the printed dots D are not formed.

In the above embodiment, the elapsed time T from the start of application of the thermal signal Q to the start of application of the electrostatic signal S is 0.
．． Although 9 to 1.1 ms is selected, it is not limited to this. For example, if T = 1.2 ms, 1
Printed dots D of approximately 36±8 μm are formed. Also,
In this example, if 0.8 ms or less is selected as the elapsed time T, the flying operation of the ink 3 does not occur, and 1.3 ms or less is selected as the elapsed time T.
It has been confirmed that if ms or more is selected, a bridging phenomenon of the ink 3 occurs, which causes the ink 3 to fly erroneously.

Example 2 The inkjet recording apparatus according to this example is as follows: Example 1
The different timing control means 7 are shown on the right.

This timing control means 7, as shown in FIG.
A data conversion circuit 51 that converts one line of serial multi-gradation image data DT into serial data with the necessary number of bits for processing, a shift register 52 that stores data from this data conversion circuit 51, and a shift register 52 that stores data from the shift register 52. A gate circuit 5 consisting of a plurality of Nantes gates 53a to 53d opens and closes gates for each pixel of interest based on the data of
Based on the third group and a predetermined clock cycle CL, heating timing signals A1a, Alb, AIC are sent to each gate circuit 53 as three opening/closing timings, an electrostatic timing signal A2 is sent to the electrostatic driver 33, and an electrostatic timing signal A2 is sent to the electrostatic driver 33 for electrostatic induction. electrode 32
A pulse generator 54 outputs a motor timing signal A3 to a stepping motor driver 34 that drives the stepping motor.
It is equipped with

In this embodiment, the data conversion circuit 51 converts the pixel of interest 1° 2.3.4.5 as shown in FIG. 12, for example.
・・・・・・Image data for n (2 bits each)
, for example rl 1.01.10.00°10...
・Parallel conversion data f10 with 3-bit configuration for Olj
0. 'o01.010,000,010...0
This is to convert it to OIJ. Further, the heating timing signals A1a to Al from the pulse generator 54 are
c is ΔT (0 in this example), as shown in FIG.
．． It is a signal with a pulse width TI (in this embodiment, TI = 1.4 m5) delayed by 1 m5), and the gate circuit 53
It is designed to be input to the A to C block lines to the group, respectively.

Note that the other configurations are the same as in the first embodiment.

Next, the operation of the inkjet recording apparatus according to this embodiment will be explained.

Now, as shown in FIG. 11, when image data DT is input to the data conversion circuit 51, this data conversion circuit 51 converts it into parallel conversion data of 3-bit configuration, and then stores it in the shift register 52. .

In this state, each heating timing signal Ala to Alc is sent from the pulse generator 54 to the gate circuit 5.
When given to the third group, the heating driver 2 corresponding to the pixel of interest 1 (image data ``11'')
The switching element 26 of No. 5 receives the heating timing signal A1a.
The switching element 26 of the heating driver 25 corresponding to the target pixels 3 and 5 (image data "10") is turned on in synchronization with the heating timing signal Alb, and the heating control signal p1 is output. The heating control signal p1 is output, and the switching element 26 of the heating driver 25 corresponding to the pixel of interest 2.n (image data "01") is turned on in synchronization with the heating timing signal AIC, and the heating control signal p1 is output. Output. Note that since the pixel of interest 4 corresponds to the image data "OO", the heating control signal p1 is not output. On the other hand, the 11th
As shown in FIG. 1 and FIG. 13, when the electrostatic timing signal A2 is applied to the electrostatic driver 33 at a predetermined timing, the electrostatic control signal p2 is output from the electrostatic driver 33 in synchronization with this. Ru.

In such an operation process, there are three types of elapsed time between the application start point of the heating control signal p1 and the application start point of the electrostatic control signal p2, so as in the first embodiment, the corresponding ink unit area M , the thermal signal Q is applied for the elapsed time corresponding to the density level of the image data before the electrostatic signal S is applied, and the high temperature heating range of the ink unit area M corresponds to the density level of the image data. (See Figures 8 and 9). Therefore, when the electrostatic signal S is applied, the ink unit w4 area M is raised according to the density level of the image data, as shown in FIG. As a result, printed dots D having diameters corresponding to the density level of the image data are formed. In addition, the image data'' o o
”, the heating control signal p1 is not output, so the heat signal Q is not applied to the corresponding ink unit area M,
This ink unit area M never flies.

[Effects of the Invention] As described above, according to the inkjet recording method and apparatus according to the present invention, the application timing of the thermal signal and the electrostatic signal is devised, and the application size is adjusted to the ink unit area to be printed. By changing the energy source according to the density level of the target image information, it is possible to form printed dots with a diameter that corresponds to the WJ level of the target image information.
There is no need to use the area gradation method to obtain a multi-gradation recorded image, and the multi-gradation recorded image can be easily reproduced while effectively preventing a decrease in resolution and complication of signal processing.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of an inkjet recording apparatus according to the present invention, FIG. 2 is an explanatory diagram showing Embodiment 1 of the inkjet recording apparatus according to the invention, and FIG. 4 is a block diagram showing the timing control means of the inkjet recording apparatus according to the first embodiment; FIG. 5 is an explanatory diagram showing an example of the operation of the data conversion circuit in the timing control means of FIG. 4; FIG. 6 is a timing chart showing the operation of the inkjet recording apparatus according to Example 1, FIGS. 9 is a graph showing the surface temperature distribution of ink corresponding to the application pattern of the thermal signal and electrostatic signal in FIG. 7; FIG. FIG. 10 is an explanatory diagram showing the relationship between image data and printed dots in Example 1;
FIG. 11 is a block diagram showing timing control means in Embodiment 2 of the inkjet recording apparatus according to the present invention;
FIG. 12 is an explanatory diagram showing an example of the operation of the data conversion circuit in the timing control means of FIG. 11, and FIG. 13 is a diagram of the second embodiment.
3 is a timing chart showing the operation of the inkjet recording apparatus according to the present invention. [Explanation of symbols] 1... Head main body 2... Ink chamber 2a... Ink discharge section 3... Ink 4... Thermal signal applying means 5... Recording sheet 6... Electrostatic signal Application means 7...Timing control means Fig. 1 Fig. 2 Fig. 3 0 50 100 150 (
'C) Ink temperature Figure 7 Figure 8 Center position of heat generating resistor Figure 9 Figure 10 Image data: Giant M mouthable printed dot: ・ ・ ・ Figure 11

Claims (1)

[Claims] 1) Applying a thermal signal according to image information to a corresponding unit area of the ink (3), and applying an electrostatic signal to the ink (3) in synchronization with the application timing of the thermal signal. , the unit area of the ink (3) to which the thermal signal has been applied is caused to fly toward the recording sheet (5) placed opposite the ink (3) by the attractive force of the electrostatic field formed based on the electrostatic signal. An inkjet recording method characterized in that the elapsed time between the start timing of applying a thermal signal to the ink (3) and the start timing of applying an electrostatic signal to the ink (3) is made variable according to the density level of the image information. 2) Ink chamber (2) in which ink discharge part (2a) is formed
a head main body (1) having a
) a thermal signal applying means (4) for applying a thermal signal according to both image information to a unit area of the ink (3) filled in the ink (3); an electrostatic signal applying means (6) for applying an electrostatic signal to the ink (3) in synchronization with the application timing of the thermal signal to form an electrostatic field directed toward the recording sheet (5); and a timing control means (7) for variably setting the elapsed time from the start timing to the electrostatic signal application start timing according to the density level of the image information, based on the timing set by the timing control means (7). The thermal signal applying means (4) and the electrostatic signal applying means (6) are activated, and the heated object is heated by the attractive force of the electrostatic field formed based on the electrostatic signal from the electrostatic signal applying means (6). ink(
An inkjet recording device characterized in that the unit area of 3) is caused to fly toward the recording sheet (5) side.