JPH0733086B2 - Inkjet printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer, and more particularly to an inkjet printer that controls ejection of ink without using a piezoelectric material.

[Prior Art] FIG. 11 is a partially exploded perspective view of a typical example of a print head of a conventional inkjet printer. Referring to FIG. 11, the print head of the conventional ink jet printer is made of a piezoelectric material and has a plurality of side walls 12 having a comb shape on the upper surface.
An ink chamber base 102 having a groove formed by 2,
Similarly, an ink chamber cover block 104 made of a piezoelectric material, having a plurality of comb-shaped grooves on the lower surface, and fixed so that the lower surface is in contact with the upper surface of the ink chamber base 102, the ink chamber base 102, and the ink. The ink chamber 106 of the ink chamber base 102 and the ink chamber cover 102 is provided with the side wall electrode 108 provided on the wall surface of each ink chamber 106 formed by each groove of the chamber cover block 104. Of the orifice plate 116 that covers the end surface on the side of the ink chamber and a portion of the upper surface of the ink chamber base 102 where the groove is not formed, and a driving integrated circuit for applying a predetermined voltage to each sidewall electrode 108 (hereinafter referred to as “driving circuit”). IC ”) 110 and. The driving IC 110 is connected to an external control circuit (not shown) by the input wiring 102, and is connected to each side wall electrode 108 by the driving wiring pattern 114.

A nozzle orifice 118 from which ink is ejected is provided at a position of the orifice plate 116 corresponding to the center of the opening of each ink chamber 106. The ink chamber cover block 104 is provided with a plurality of ink introduction holes 120 for supplying ink to each ink chamber 106.

FIG. 12A is an enlarged sectional view of the side wall 122. The sidewall 122 is part of the ink chamber base 102 of piezoelectric material and is also piezoelectric. Separate sidewall electrodes 108a and 108b are provided on both side surfaces of the sidewall 122, respectively. Side wall 122 is the 12th
It is polarized in the direction indicated by arrow D in the figure.

A positive voltage is applied to the side wall electrode 108a and a negative voltage is applied to the side wall electrode 108b. The sidewall 122 is polarized. Therefore, as shown in FIG. 12B, the side wall 122 is formed by the inverse piezoelectric effect.
Is sheared. This phenomenon is called the piezoelectric shear mode effect. Each side wall on the lower surface of the ink chamber cover block 104 is polarized on the side opposite to the arrow D.

FIG. 13 is a sectional view taken along line XI-XI of FIG. First
Figure 13 shows the state of the print head during operation. It should be noted that the ink chamber 10 is shown in FIG. 11 for simplification of the drawing.
It means that only 6 are drawn. In an actual print head, a larger number of ink chambers 106a, 106b, 106c, 106d, ... Are provided as shown in FIG.

The operation of the print head of the conventional inkjet printer will be described with reference to FIGS. 11 to 13. The ink chamber 106 is filled with the ink supplied from the ink introduction hole 120. The driving IC 110 applies a predetermined voltage to each of the sidewall electrodes 108 according to the dot pattern of the print data. Ink chamber block 102 and ink chamber cover block 104
The sidewalls provided on each of the electrodes are sheared and deformed according to the voltage applied to the sidewall electrode 108.

The cross-sectional shape of each ink chamber 106 changes due to the deformation of the side wall. The pressure increases in the ink chamber 106 where both side walls are deformed inward and the cross-sectional area thereof is reduced. Therefore, ink is ejected from the nozzle orifice 118. No ink is ejected from the other ink chambers.

In FIG. 13, no voltage is applied to the sidewall electrodes 108a and 108b. A positive voltage is applied to the side wall electrodes 108c and 108e. A negative voltage is applied to the sidewall electrodes 108d and 108f. Among the side walls, the side walls 122c, 122d, 122e, 122f and the like having a potential difference between the side wall electrodes on both sides thereof,
It deforms as shown in FIG. After this side wall 122
Since the plus and minus of the voltage applied to the sidewall electrodes on both surfaces of c and 122e are opposite to that of the sidewalls 122d and 122f, the opposite deformation occurs.

Due to the side-changing shear deformation as described above, the ink chamber 106d,
The area of 106f is reduced and ink is ejected from these ink chambers. No ink is ejected from the other ink chambers. As a result, a set of dots for one vertical column is formed on the recording paper arranged near the orifice plate 116 of the print head. The print head moves in the direction orthogonal to the arrangement direction of the ink chambers 106 to form the next set of dots for one vertical column.

The above operation is repeated to form a character as a set of dots on the recording paper. However, as is clear from FIG. 12, since two adjacent ink chambers share the side wall, it is impossible to eject ink from them at the same time. Therefore, a method is used in which every other ink chamber is alternately used to form dots in each row.

[Problems to be Solved by the Invention] However, the conventional inkjet printer has the following problems. One of the problems is that the material forming the side wall of the ink chamber is limited to the piezoelectric material. It goes without saying that it is desirable to be able to use more diverse materials.

Another problem is that manufacturing conventional inkjet printers is laborious. The piezoelectric material needs to be polarized in advance. Moreover, when exposed to a temperature above the temperature called the Curie point, the piezoelectric material dislocations to the paraelectric layer and loses its polarization.
Therefore, when the piezoelectric material is processed to form the print head, it is necessary to control the processing process so that the temperature does not exceed the Curie point. However, it is time-consuming to manufacture an inkjet printer in consideration of these points. Further, it is desirable that the nozzles can be highly integrated and the manufacturing is easy in that case as well.

Therefore, an object of the present invention is to provide an inkjet printer which does not use a voltage material, is easy to manufacture, and is suitable for high integration.

[Means for Solving the Problems] The inkjet printer according to the present invention includes a plurality of
An array of aligned and individually controllable ink ejection nozzles is included, and the ink ejection nozzles are individually ejection-controlled while performing relative displacement between the recording object and the alignment direction and the intersecting direction. An ink jet printer in which a character is expressed as a dot array of ejected ink in an alignment direction and a cross direction by means of a plurality of side walls formed in a comb shape in the alignment direction on a surface. An ink chamber base made of an insulating material having a plurality of grooves, a plurality of side wall electrodes bonded to the side wall so as to cover both side surfaces and an upper surface of each of the plurality of side walls and insulated from each other, and An upper surface cover member that is mounted on the ink chamber base so as to cover the surface and an ink is ejected that is mounted on the ink chamber base so as to cover the end surface of the ink chamber base. An end surface cover member having a mouth portion, the ink jet nozzle, the wall member formed of a side wall and a side wall electrode formed on the side wall, facing each other, an upper surface cover member, a bottom surface of the groove of the ink chamber base, And a means for applying a control voltage to the side wall electrodes of the opposing wall members so as to control the ink ejection nozzles in accordance with the dot array data for representing the character.

[Operation] Means for applying a control voltage to the side wall electrodes of the opposing wall members are
According to the dot array data that should represent the character,
An appropriate control voltage is applied to the side wall electrode of the wall member. Out of the facing wall members, the facing wall members having the side wall electrodes to which the control voltages different from each other are applied store the charges of different polarities. Therefore, the Coulomb force due to the mutual electric charges acts on the opposing wall members as an attractive force. Since the wall member bends easily, the attractive force of the Coulomb force
These opposing wall members are formed so as to approach each other.
The volume of the ink ejection nozzle defined by these opposing wall members decreases. As a result, the pressure inside the ink ejection nozzle rises, and ink is ejected from the ink ejection nozzle.

On the other hand, the Coulomb force does not act as an attractive force between the opposing wall members having the side wall electrodes to which the same control voltage is applied. Therefore, the volume of the ink ejection nozzle defined by these opposing wall members is at least reduced, and no ink is ejected.

Each jet nozzle is individually jet controlled as described above. When the ejection nozzles are aligned, relative displacement is performed between the ejection nozzles and the recording object in the alignment direction and the intersecting direction to express a character as an array of ejection dots.

[Embodiment] FIG. 1 is a perspective view of a print head of an inkjet printer according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the print head shown in FIG. FIG. 3 is a view in the direction of arrow III-III in FIG.

With reference to FIGS. 1 to 3, this print head has a plurality of grooves formed by separating a plurality of comb-shaped side walls 12 (12a, 12b, 12c, 12d), and has a small Young's modulus. A material, for example, an ink chamber base 10 made of plastic or the like, and the side walls 12a, 12b, 12c, 12d of the ink chamber base 10 are adhered to the respective side walls 12a, 12b, 12c, 12d so as to cover both side surfaces and an upper surface thereof. And a plurality of side wall electrodes 16a, 16b, 16 insulated from each other
c, 16d and other side wall electrodes that are glued to the side walls of the groove at both ends.
End side wall electrodes 14a, 14b insulated from 16a, 16b, 16c, 16d
A cover plate 24 fixed on the ink chamber base 10 so as to cover the grooved portion thereof, and a portion of the ink chamber base 10 where the groove is not formed. 16a, 16b, 16c, 16d, 14a, 14b drive IC18 for applying a predetermined voltage, and the ink chamber base 10
Of the orifice plate 26 fixed so as to cover the end on the side where the groove is open.

Each groove provided in the ink chamber base 10 has its upper portion defined by a cover plate 24, and forms ink chambers 30a, 30b, 30c, 30d, 30e for containing ink therein. Each ink chamber 30a, 30b, 30 of the orifice plate 26
A nozzle orifice 28 from which ink is ejected is formed at a position corresponding to the center of the cross section of c, 30d, 30e.
Each ink chamber 30a, 30b, 30c, 30d, 30 of the cover plate 24
On the e, an ink introduction hole 32 for supplying ink into each ink chamber is provided.

On the ink chamber base 10, an input wiring 20 for connecting an external control circuit (not shown) and the driving IC 18 and the driving wiring
Each output terminal of IC18 and each side wall electrode 16a, 16b, 16c, 16d, 14
A drive wiring pattern 22 for connecting a and 14b is formed.

The depth of each ink chamber 30a, 30b, 30c, 30d, 30e is represented by d, the height is represented by h, and the width is represented by a.

FIG. 4 is a view showing the operating state of the print head shown in FIG. 1 as seen from the direction of arrows III-III in FIG. It should be noted that in FIG.
12a, 12b, 12c and 12d are drawn so as to have a predetermined deformation.

The operation of the print head will be described with reference to FIGS. The driving IC 18 receives each of the side wall electrodes 14a, 14b, 16a, 16b, 16c, 16d based on the signal input from the input wiring 20.
Apply a predetermined voltage to. For how to apply this voltage,
It will be described in detail later.

Now, the sidewall electrodes 14a, 16a, 16d, and 14b have a ground potential (hereinafter GN).
D), it is assumed that the positive voltage V is applied to the side wall electrodes 16b and 16c. For example, a potential difference V between the sidewall electrodes 16a and 16b
Occurs. Ignoring the thickness of the side wall electrodes 16a and 16b, the electrostatic capacitance C between the side wall electrodes is obtained by C = ε × h × d / a. However, ε is the dielectric constant of the ink. Therefore, the sidewall electrodes 16a and 16b have an absolute value of Q = CV, and charges having different signs are accumulated. Double-sided electrode
A Coulomb force F expressed by the following equation acts between 16a and 16b.

In this case, the Coulomb force F acts as an attractive force. Side wall electrode
16a and 16b are adhered to the side walls 12a and 12b, respectively. Since the side walls 12a and 12b are made of a material having a small Young's modulus, they are easily bent by a small force. Therefore the sidewalls 12a, 1
2b deforms toward each other. The volume of the ink chamber 30b defined by the side walls 12a and 12b decreases, and the pressure inside thereof increases. As a result, ink is ejected from the nozzle orifice 28 of the ink chamber 30b to record dots on the recording paper.

On the other hand, there is no potential difference between the sidewall electrodes 16b and 16c. No attractive force acts on the side walls 12b and 12c. The volume of the ink chamber 30c does not decrease at least, and ink is not ejected from the ink chamber 30c.

As described above, ink is ejected from the ink chambers defined by the two side walls by applying different voltages to the side wall electrodes provided on the two adjacent side walls. Further, by applying the same voltage to the side wall electrodes of the two adjacent side walls, ink is not ejected from the ink chambers defined by those two side walls. Therefore, by controlling the potential of the side wall electrodes on each side wall, it is possible to control the ejection of ink from each ink chamber, and it is possible to express a character as an array of dots on the recording paper.

However, even in this print head, it is impossible to eject ink from two adjacent ink chambers at the same time. Therefore, as in the prior art, every other ink chamber is grouped into two ink chamber groups, and the ink chambers of each group are alternately used to form dots.

The present invention utilizes Coulombic electrostatic forces acting between charges instead of using the piezoelectric shear mode of piezoelectric materials. Therefore, there is an effect that the restrictions on the constituent material of the print head are reduced, the polarization treatment is not necessary, and the temperature of the material is not particularly required to be controlled during the processing.

However, there are technical problems to be solved in order to realize the present invention. It is a method of determining the voltage to be applied to each electrode. One side wall generally faces the other side wall in both directions. Therefore, the voltage applied to the sidewall electrodes of the two sidewalls defining each ink chamber to drive each ink chamber must be determined in relation to the other sidewall electrodes.

FIG. 5 is a block diagram showing an embodiment of a circuit for realizing the ink jet printer according to the present invention to solve the above technical problems. With reference to FIG. 5, this inkjet printer has an input port 34 for receiving print data from the outside, a bus 36 connected to the input port 34, and a CPU for controlling the entire inkjet printer, which is connected to the bus 36. (Central Processing Unit) 38,
A ROM (Read Only Memory) 40 that is connected to the bus 36 and in which a program executed by the CPU 38 and a dot pattern of characters to be printed are stored in advance, and is connected to the bus 36 and is used as a work area of the CPU 38. RAM (Rand
om Access Memory) 42 and a bus 36, and a timer / mounter 44 for generating a timing signal for synchronizing the operation of the entire circuit, and one line of a character to be printed which is connected to the bus 36. A print data output port 48 for outputting a dot pattern signal according to the dot pattern, and a drive signal output port 58 connected to the bus 36 and outputting a signal for receiving a command from the CPU 38 and controlling the drive system. , An electrode signal generation circuit 52 connected to the print data output port 48, for generating an electrode signal to be applied to the electrode of each ink chamber in response to a dot pattern signal, and an electrode signal generation circuit 52 Is connected to the print head 54 for forming a dot row by ejecting ink in accordance with the dot pattern of the character and the timer / counter 44, and using an encoder or the like. By detecting the relative position of the shaped head 54 and the recording sheet, a head position detecting means 46 for generating a reference signal for determining the timing of ink ejection, a timer / counter 44 and the electrode signal generating circuit
Print pulse generating means 50 for receiving a signal indicating a print timing from the timer / counter 44 and outputting a print pulse signal for operating the electrode signal generating circuit 52, and a drive signal output port 58. And a motor driver 60 and a motor 62 for moving the print head 54 and / or the recording paper in a predetermined direction at a predetermined speed.
Including and The timer / counter 44 is also connected to the interrupt terminal of the CPU 38.

The printhead 54 includes an electrode group 56 that includes a plurality of sidewall electrodes, as shown by FIGS.

Among the elements shown in FIG. 5, the new ones are the electrode signal generation circuit 52 and the print head 54. Figure 6 shows the electrode group
It is a schematic diagram which shows the structure of 56. Referring to FIG. 6, electrode group 56
Is 2k + 1 electrodes E1, E2, ..., E (2k), E (2k +
Including 1). Ink chambers C1, C2,
..., C (2k) is formed. That is, the print head 54 can form 2k dots whose positions are different from each other.

FIG. 7 is a more detailed block diagram of the electrode signal generation circuit 52. Referring to FIG. 7, the electrode signal generation circuit 52 is connected to the print data output port 48 by k signal lines 83,
Of the dot pattern containing 2k dots, the signals for the odd k dots are input and only the odd ones of the 2k ink chambers C1, C2, ..., C2 (k) are input. Connected to the print data output port 48 by an odd-number dot signal generation circuit 64 for generating an odd-number dot signal given to each electrode E1, E2, ..., E (2k + 1) for driving, and k signal lines 85, When signals for even-numbered k dots are input, 2k ink chambers C1, C2, ..., C (2k)
Of each electrode E to drive only the even one
, E2, ..., E (2k + 1) are connected to the even dot signal generation circuit 66 for generating the even dot signal, the odd dot signal generation circuit 64, and the even dot signal generation circuit 66, and the signal line 92 An ODD / EVEN switching circuit 68 for inputting an ODD / EVEN switching signal indicating switching between even-numbered dots and odd-numbered dots, alternately selecting an odd-numbered dot signal and an even-numbered dot signal, and outputting the selected dot signal line 91 to the selected dot signal line 91. , ODD / EVEN switching circuit
In response to the print pulse signal from the signal line 93, the signal inputted from the selected dot signal line 91 is amplified to be electrode signals P1, P2, ..., P (2k), P (2k + 1). ) Output electrode signal gate circuit 70.

The odd dot signal generation circuit 64 and the ODD / EVEN switching signal 68, the even dot signal generation circuit 66 and the ODD / EVEN switching circuit 68, the electrode signal gate circuit 70 and the ODD / EVEN switching circuit 68 are each 2k +.
They are connected by one odd dot signal line 87, even dot signal line 89, and selection dot signal 91.

FIG. 8A is a circuit diagram showing a circuit configuration of the odd dot signal generation circuit 64. Odd dot signal generation circuit with reference to FIG. 8A
64 is a k signal line for receiving a signal representing an odd-numbered dot among 2k signals representing a dot pattern
b1, b3, b5, ..., b (2k-3), b (2k-1) and GND
A signal line 72 connected to the electric potential, and k-2 in which one of the inputs is connected to each of the k-2 signal lines after the signal line b5.
And an exclusive OR circuit (hereinafter referred to as an EXOR circuit) 74.

The other input of each EXOR circuit 74 is connected to the output of the EXOR circuit 74 provided in the adjacent signal line with the smaller number. For example, the other of the inputs of the EXOR circuit 74 whose one end is connected to the signal line b7 is the EX
It is connected to the output of the OR circuit 74.

However, the EXOR circuit 74 with one input connected to the signal line b5
The signal line b3 is directly connected to the other input of the. The EXOR circuit 74 functions to determine the electrode signal to be applied to each electrode.

The signal line b1 becomes the odd dot signal line OD1 as it is. The signal lines 72, b3 and the outputs of the k−2 EXOR circuits 74 are each branched into two, and 2k lines and the signal lines OD2, OD3, ...
It becomes OD (2k) and OD (2k + 1). Therefore, the odd dot signal generation circuit 64 has 2k + 1 odd dot signal lines as outputs.

FIG. 8B is a circuit diagram showing a circuit configuration of the even dot signal generation circuit 66. Referring to FIG. 8B, an even dot signal generation circuit
66 is a signal line 78 connected to the GND potential and k signal lines b2, b4, ..., b (2) for receiving a signal representing an even-numbered dot among 2k signals representing a dot pattern.
k) and k-1 signal lines after the signal line b4 include k-1 EXOR circuits 80 to which one of the inputs is connected.

The other input of each EXOR circuit 80 is connected to the output of the EXOR circuit 80, which is connected to the signal line with the adjacent smaller number. However, the other input of the EXOR circuit 80, one input of which is connected to the signal line b4, is directly connected to the signal line b2. These EXOR circuits 80 perform the function of determining the electrode signal applied to each electrode.

Each output of the signal lines 78, b2 and each EXOR circuit 80 is 2
It branches into books. However, the output of the EXOR circuit 80 to which the signal line b (2k) is connected is not branched. Therefore, the output from the even dot signal generation circuit 66 is, as shown in FIG. 8B, 2k + 1 even dot signal lines EV1, EV2, ..., EV.
Including (2k) and EV (2k + 1).

FIG. 9 is a circuit diagram of an example of the ODD / EVEN switching circuit 68. Referring to FIG. 9, the ODD / EVEN switching circuit 68 is connected to the signal lines for one dot each of the odd dot signal generation circuit 64 and the even dot signal generation circuit 66, and is input from the signal line 92. In response to the ODD / EVEN switching signal, 2k + 1 selectors 82 for switching between the odd dot signal and the even dot signal and outputting to the selected dot signal line 91 are included.

The odd dot signal line and the even dot signal line input to each selector 82 both determine the dot signal applied to the same electrode. For example, the second electrode
One of the inputs of the selector 82, to which the selection dot signal S2 that determines the voltage applied to E2 is connected, is connected to the signal line OD2 and the other is connected to EV2.

FIG. 10 is a circuit diagram showing an example of the selector 82. The contents of this selector 82 are publicly known. Therefore, detailed description of its configuration and operation is omitted. FIG. 10 shows the selector 82 that determines the dot signal to the first electrode E1. One of the inputs of the selector 82 is connected to the odd dot signal line OD1 and the other is connected to the even dot signal line EV1. In the case of the configuration of FIG. 10, when “1” is applied to the signal line 92, the content of EV1 is output as it is to the selected dot signal line S1. Signal line 9
When “0” is applied to 2, the content of OD1 is output as it is to the selected dot signal line S1.

The operation of the inking jet printer will be described with reference to FIGS. Character data is input to the input port 34 from the outside. The CPU 38 temporarily stores the character data in the RAM 42, then reads the dot pattern corresponding to the character from the ROM 46, and outputs the dot pattern signal indicating the dot pattern for one column to the print data output port 48. In this example, one row of dots contains 2k dots. Therefore, the print data output port 48
For each of the 2k dots, 2k dot pattern signals are input, which binary-codes "0" and "1" to indicate whether or not to print each dot.

The print data output port 48 outputs an odd-numbered k dot pattern signal out of the 2k dot pattern signals to the signal line.
It is sent to the odd dot signal generation circuit 64 via 83. The print data output port 48 outputs the even-numbered k dot pattern signals via the signal line 85 to the even dot signal generation circuit 66.
Send to.

In the odd dot signal generation circuit 64, the dot pattern signal is processed as described below. The dot pattern signal for the first dot is output to the signal line OD1 as it is. The signal “0” is given to the signal lines OD2 and OD3.

In FIG. 8A, when n is a natural number, whether or not ink is ejected from the 2nth ink chamber is determined by the signal line OD (2
n) and OD (2n + 1). However, it is clear that these signal lines OD (2n) and OD (2n + 1) are branched from the same signal line, and the values of these signals are the same. Therefore, there is no potential difference between both side walls of the 2n-th ink chamber. Therefore, ink is not ejected from the even-numbered ink chambers.

On the other hand, whether or not ink is ejected from the 2n−1th ink chamber depends on the values of the signal lines OD (2n−1) and OD (2n). If the signal values of these lines are equal to each other, 2n
No ink is ejected from the -1st ink chamber. If the values of these signals are different from each other, ink is ejected from the (2n-1) th ink chamber.

The EXOR circuit 74 determines the signal value of the odd dot signal line OD (2n) from the signal values of the odd dot signal line OD (2n-1) and the signal line b (2n-1). That is, if the value of the signal on the signal line b (2n−1) is “0”, the signal line OD (2
The signal of n) is set to the same value as the signal of the signal line OD (2n-1). If the signal value of the signal line b (2n-1) is "1", the value of the signal line OD (2n) is set to a value different from the value of the signal line OD (2n-1).

As a result, if the signal value of the signal line b (2n-1) is "0", ink is not ejected from the 2n-1th ink chamber. If the value of the signal on the signal line b (2n-1) is "1", ink is ejected.

FIG. 8B is a table showing the signal values of the respective signal lines when n = 3. Consider a case where the value of the signal line b5 is “0” with reference to FIG. 8B. If the value of the signal line OD5 is "0", the value of the signal of the signal line OD6 is "0". If the value of the signal line OD5 is "1", the value of the signal of the signal line OD6 is "1". That is, when the value of the signal line OD5 is “0”, the signal values of the signal lines OD5 and OD6 are equal. At this time, the voltages applied to both side wall electrodes of the fifth ink chamber are equal, and ink is not ejected from this ink chamber.

If the value of the signal line b5 is “1”, the combination of the value of the signal line OD5 and the signal line OD6 is “0” and “1” or “1” and “0”. Either of the combinations. Therefore, the ink is ejected from the fifth ink chamber.

The even dot signal generation circuit 66 shown in FIG. 8C performs the same operation as the odd dot signal generation circuit 64. The former is different from the latter in that the former is configured so that the voltages applied to both side walls of the odd-numbered ink chambers are always equal. Then, when n is a natural number, the value of the signal on the line signal EV (2n + 1) is
n) and the value of the signal line b (2n). FIG. 8D is a table showing the relationship between the signal values of the signal lines when n = 3.

Referring to FIG. 8D, when the value of the signal on signal line b6 is “0”, the value of the signal on signal line EV7 becomes equal to the value of the signal on signal line EV6. Therefore, no ink is ejected from the sixth ink chamber. On the other hand, if the value of the signal on the signal line b6 is “1”,
The signal value of the signal line EV7 and the signal value of the signal line EV6 are different values. Therefore, ink is ejected from the sixth ink chamber.

In the above-mentioned operation, a reference is required to uniquely determine the output of each signal line. In the odd dot signal generation circuit 64, the signal line 72 serves as a reference, and in the even dot signal generation circuit 66, the signal line 70 serves as a reference. The other output values are determined one after another in relation to these reference signal lines.

The head position detecting means 46 detects the relative position between the print head 54 and the recording paper in order to determine the timing of ink ejection from the print head 54, and outputs a head position detection signal. The timer / counter 44 responds to the head position detection signal and generates a timing signal for determining the timing of the operation of the entire inkjet printer. The timer / counter 44 also sends to the CPU 38 and the print pulse generating means 50 an interrupt signal that determines the timing of ejecting ink.

The CPU 38 outputs a signal indicating ODD / EVEN switching to the drive signal output port 58 in order to alternately switch recording of odd-numbered dots and recording of even-numbered dots. The drive signal output port 58 responds to the signal indicating the ODD / EVEN switching, and sends the ODD / EVEN switching signal for operating each selector 82 to the signal line 92. The value of the ODD / EVEN switching signal is, for example, "0" when recording odd-numbered dots, and is "1" when recording even-numbered dots.

Therefore, select dot signal line from ODD / EVEN switching circuit 68
The signal 91 becomes a signal for recording an odd numbered dot when the value of the ODD / EVEN switching signal is “0”, and an even numbered dot when the value of the ODD / EVEN switching signal is “1”. It becomes a signal for recording.

The print pulse generation means 50 outputs a print pulse indicating the print timing to the signal line 93. Electrode signal gate circuit 70
Outputs an electrode signal in response to the odd dot signal or even dot signal input from the ODD / EVEN switching circuit 68 in response to the print pulse signal. At this time, if the value of the selected dot signal input from the ODD / EVEN switching circuit 68 is “0”, the voltage of the corresponding electrode signal is made equal to the ground potential,
If it is "1", it is set to a predetermined voltage V. In the electrode group 56, each electrode E1, E2, ..., E (2k + 1)
Then, a voltage corresponding to the dot pattern and the recording of even-numbered dots and the recording of odd-numbered dots is applied to record one row of odd-numbered dots or even-numbered dots.

The motor 62 is driven by the CPU 38 via the motor driver 60 and the drive signal output port 58. The motor 62 changes the relative positions of the inkjet 54 and the recording paper.

The CPU 38 repeats the above-mentioned operation while switching between even-numbered dots and odd-numbered dots until the character printing is completed. Characters are expressed on the recording paper as an array of dots formed by inkjet.

When the character printing is completed, the CPU 38
The next character code arriving at is read. Then, the above operation is further repeated.

In the above operation, the rows of only odd dots and the rows of only even dots are formed alternately. Therefore, printing is not perfect as it is. However, if the print head 54 is reciprocated on the same line and the recording operation is performed twice, it is possible to form both odd dots and even dots in each column.

As described above, according to the present invention, it is possible to provide an inkjet printer capable of expressing a desired character by controlling ink ejection without using a piezoelectric material.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the signal value applied to each electrode was determined by the circuit means. However, it is also possible to perform these operations by a program in the CPU 38.

[Effect] In the inkjet printer according to the present invention,
A control voltage is applied to each wall member according to the dot array data that should represent the character. Charges having different polarities are accumulated in the opposing wall members to which different control voltages are applied. Therefore, the Coulomb force due to the mutual electric charges acts on the opposing wall members as an attractive force.
Since the wall members are easily bent, the opposing wall members are deformed toward each other by this attractive force. The volume of the ink ejecting nozzle defined by the deformed opposing wall members decreases. As a result, the pressure inside the ink ejection nozzle rises, and ink is ejected from the ink ejection nozzle.
On the other hand, the Coulomb force does not act as an attractive force between the opposing wall members to which the same control voltage is applied. Therefore, ink is not ejected from the ink ejecting nozzles defined by the facing wall members.

Each ejection nozzle is individually ejection-controlled as described above, and expresses a character as an array of dots formed by the ejected ink.

Therefore, the wall member of the ink jet nozzle does not have to be made of a piezoelectric material. It is not necessary to polarize the wall member in advance. Moreover, there is no particular need to control the temperature to maintain the polarization of the wall member during processing. Further, since each wall member may be formed by adhering the side wall electrode to the surface of the side wall formed on the ink chamber base, it can be easily manufactured and is easily destroyed even when the wall member is deformed. There is no fear that it will happen. Further, even if the nozzle interval is narrowed, the area of the electrode does not decrease, and the reduction of the volume of the ink chamber due to the deformation of the wall member does not become too small. Therefore, even if high integration is performed, good printing can be performed.

Therefore, according to the present invention, without using a piezoelectric material,
An inkjet printer that is easy to manufacture and suitable for high integration can be provided.

[Brief description of drawings]

1 is a partially exploded perspective view of a print head of an ink jet printer according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the print head of FIG. 1, and FIG. 3 is FIG. FIG. 4 is a view taken in the direction of the arrow III-III of FIG. 4, FIG. 4 is a view taken in the direction of the arrow III-III of FIG. 1, and is a schematic view showing the operating principle of the inkjet printer of the present invention, and FIG. 6 is a circuit block diagram of an embodiment, FIG. 6 is a schematic block diagram of an electrode group of the print head of FIG. 5, and FIG. 7 is a detailed block diagram of the electrode signal generation circuit of FIG. , FIG. 8A is a more detailed block diagram of the odd dot signal generation circuit of FIG. 7, FIG. 8B is a table showing the mutual relationship of the signal values of the signal lines shown in FIG. 8A, and FIG. Figure is a more detailed block diagram of the even dot signal generation circuit of Figure 7, Figure 8D is shown in Figure 8C. 9 is a table showing the relationship between the values of the signals of the respective signal lines to be generated, FIG. 9 is a block diagram of the electrode signal gate circuit of FIG. 7, and FIG. 10 is a circuit block diagram showing an example of a selector. FIG. 11 is a perspective view of an example of a print head of an ink jet printer using a conventional piezoelectric material, and FIGS. 12A and 12B are conventional wall members showing the deformation of the piezoelectric material in the piezoelectric shear mode. 13 is a cross-sectional view of FIG. 13, and FIG. 13 is a view taken in the direction of arrow XIII-XIII in FIG. 11, showing a deformed state of the piezoelectric material. In the figure, 10 is an ink chamber base, 12, 12a to 12d are side walls of the ink chamber, 14 is an end side wall electrode, 16 is a side wall electrode, 18 is a driving IC,
24 is a cover plate, 26 is an orifice plate, 28 is a nozzle orifice, 30 is an ink chamber, 32 is an ink introduction hole, 34
Is input port, 36 is bus, 38 is CPU, 40 is ROM, 42 is RA
M, 44 are timer / counter, 46 is head position detecting means, 4
8 is the print data output port, 50 is the print pulse generation means, 5
2 is an electrode signal generation circuit, 54 is a print head, 56 is an electrode group, 5
8 is a drive signal output port, 64 is an odd dot signal generation circuit, 66 is an even dot signal generation circuit, 68 is an ODD / EVEN switching circuit, 70 is an electrode signal gate circuit, 74 and 80 are EXOR circuits, 82 is a selector, 87 Is an odd dot signal line, 89 is an even dot signal line, 91 is an ODD / EVEN switching signal line, and 93 is a print pulse signal line. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An array of a plurality of aligned and individually ejectable ink ejecting nozzles, wherein the ink ejecting nozzles perform relative displacement with respect to a recording object in a direction intersecting the aligning direction. An ink jet printer in which a character is expressed as a dot array of ejected ink in the alignment direction and the intersecting direction by individually controlling ejection, and a plurality of comb-shaped ink jet printers are formed on the surface in the alignment direction. An ink chamber base made of an insulating material, the ink chamber base having a plurality of grooves formed by separating the formed sidewalls; and an adhesive bonded on the sidewalls so as to cover both side surfaces and an upper surface of each of the plurality of sidewalls. A plurality of side wall electrodes insulated from each other, an upper surface cover member mounted on the ink chamber base so as to cover the surface of the ink chamber base, and an end surface of the ink chamber base. And an end surface cover member having an opening through which ink is ejected, the ink ejection nozzle being formed of the side wall and the side wall electrode formed on the side wall. Data of a dot arrangement that is defined by a wall member facing each other, the top cover member, the bottom surface of the groove of the ink chamber base, and the end face cover member, and that represents the character of the ink ejection nozzle. So as to control the ejection, the means for applying a control voltage to the side wall electrode of the opposing wall member controls the distance between the opposing wall members by the action of the control voltage to control the ejection of ink. Injet printer.