JPH10805A - Electrostatic ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the recording quality in the whole spacing areas by providing recording gap measuring means at both ends aside of an ejection electrode of a head. SOLUTION: When a recording paper 5 is fed in the arrow H direction along the disposition direction of an ejection electrode 3 in a recording head 1, the recording head 1 is positioned at one end of a spacing area 4 before starting the recording operation. The recording gap between an A point and a B point is measured by sensors 7 provided at both ends. The recording head 1 spaces to the other end of the spacing area 4 so that the recording gap between a C-point and a D-point is measured. Based on the measurement in the four points, a controlling portion controls a θ rotation mechanism and a θ rotation mechanism for finely moving a counter electrode 2 for making a correction in the θrotation direction and the θ rotation direction such that the recording gap from the ejection electrode 3 to the recording paper 5 can always be constant in the recording operation thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for performing recording by attaching toner to a recording medium, and more particularly to control of a recording gap of a recording apparatus utilizing an electrostatic ink jet recording system.

[0002]

2. Description of the Related Art It is important to keep the recording gap constant even in a conventional ink jet recording apparatus.
There are roughly two ways to do this. One is a means for correcting by a mechanical structure, and the other is a means for correcting by an electric signal. For example, there is an example described in Japanese Patent Application Laid-Open No. 61-280941 as an example of correcting by a mechanical structure. In this method, recording is performed by spacing the recording paper while adsorbing it on an electrostatic attraction plate formed in the vicinity of the same member as the recording head. Whatever the case, the gap between the recording head and the recording paper in the recording section is kept relatively constant. Further, as an example of a correcting means using an electric signal, there is one described in Japanese Patent Laid-Open No. 4-110170. In this method, a voltage is applied between the conductive ink and the electrode in a state where the mesh sheet and the recording paper are pressed against each other by the ink supply member to generate an electric field, and the ink is filled in the mesh hole only when an electrostatic force is applied to the ink. In a method of penetrating and attaching ink to recording paper, the recording quality is kept constant by detecting the recording gap between the discharge unit and the control unit and controlling the applied voltage.

[0003]

By the way, in the electrostatic ink jet recording system, in a state where the charged toner particles are distributed in an insulating solvent in an electrostatic field, a pulse-shaped pulse having the same polarity as the charged toner on the discharge electrode is formed. By applying the high voltage, the toner is caused to fly in the direction of the counter electrode, which is separated from the discharge unit by a certain distance. That is, ejection occurs when the electric field intensity between the ejection electrode and the counter electrode exceeds a certain threshold. The electric field intensity between the discharge electrode portion and the counter electrode is approximately represented by the following equation <l>. E = △ V / d (1) where E: electric field between the discharge electrode and the counter electrode ΔV: potential difference between the discharge electrode and the counter electrode d: distance between the discharge electrode and the counter electrode This means that the change of the recording gap affects the ejection characteristics. For example, when the rightmost ejection electrode is closer to the counter electrode than the leftmost ejection electrode in the ejection electrode array, the rightmost dot is larger than the leftmost dot, or the rightmost dot does not eject at the leftmost end even if it ejects normally at the rightmost end. Things happen. Even in a conventional ink jet system such as a bubble jet system or a piezo system, in such a case, a displacement of a landing position of a droplet may occur, but the discharge characteristic itself of each discharge unit does not change due to a recording gap. . In other words, in the electrostatic ink jet recording method, the recording gap is an important parameter for the ejection characteristics, and therefore it is necessary to control the gap more precisely than in the conventional ink jet method. For example, Japanese Patent Application Laid-Open No. 61-280
No. 941 and Japanese Unexamined Patent Publication No. 4-110170, although the recording gap is fixed or detected, the accuracy of detection is low, and the recording gap in the detecting means at the detection position is low. Even if it is constant, the recording gap of each ejection electrode in the spacing area of the serial printer is not necessarily constant.

Accordingly, an object of the present invention is to make it possible to stabilize the recording quality in all the spacing areas by ascertaining the recording gap between each ejection electrode and the recording medium in all the spacing areas. An object of the present invention is to provide an electronic ink jet recording apparatus.

[0005]

According to another aspect of the present invention, there is provided an electrostatic ink jet recording apparatus according to the first aspect of the present invention, which is capable of discharging an insulating ink containing a charged toner to the outside. A head having a recording medium disposed on the head side while being opposed to the ejection section of the head, and a plurality of electrodes arranged in an array on the counter electrode side of the head, and a pulse voltage is applied. An ejection electrode for performing recording on a recording medium by ejecting the toner in the ink from the ejection unit in the direction of the counter electrode due to a potential difference that occurs in the electrostatic ink jet recording apparatus. The recording gap measuring means for measuring the recording gap up to the recording medium is provided at both ends of the array.

According to a second aspect of the present invention, there is provided an electrostatic ink jet recording apparatus according to the first aspect, wherein a spacing operation for moving the head along the counter electrode is performed before the start of the recording operation. The recording gap measuring means measures the recording gap at three or more different positions.

According to a third aspect of the present invention, there is provided the electrostatic ink jet recording apparatus according to the second aspect, wherein the two recording gap measuring means respectively measure the recording gaps at both ends in a spacing direction. It is characterized by.

According to a fourth aspect of the present invention, there is provided an electrostatic ink jet recording apparatus according to any one of the first to third aspects, wherein the facing ink jet recording apparatus is provided based on a measurement result by the recording gap measuring means. It is characterized by having a control unit for finely moving the electrode or the ejection electrode.

According to a fifth aspect of the present invention, there is provided an electrostatic ink jet recording apparatus according to any one of the first to third aspects, wherein the ejection is performed based on a measurement result by the recording gap measuring means. It is characterized by having a control unit for changing the voltage applied to the electrode.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a recording section of an electrostatic ink jet recording apparatus according to the present invention, and FIG. 2 is an enlarged view of arrow F in FIG. The electrostatic ink jet recording apparatus has a recording head 1, and the recording head 1 includes:
An ink chamber (not shown) whose inside is filled with insulating ink containing charged toner, and a discharge unit (not shown) provided on one side of the ink chamber and communicating the ink chamber with the outside are provided. ing.

Discharge direction of discharge unit (indicated by arrow I in FIG. 2)
A counter electrode 2 is disposed in front of the recording head 1. In the vicinity of a discharge portion of the recording head 1 on the side of the counter electrode 2, a pulse voltage is applied to cause the toner in the ink to move in the direction of the counter electrode 2 due to an instantaneous potential difference. Are provided in a state where the plurality of ejection electrodes 3 are arranged in one direction. Note that the recording head 1 performs spacing to move in a direction orthogonal to the arrangement direction of the ejection electrodes 3 and along the counter electrode 2 (the direction indicated by the arrow G in FIG. 1). ,
The range of the spacing of the recording head 1 is a spacing area 4 indicated by a broken line in FIG.

Here, although not shown, the electrostatic ink jet recording apparatus stores the ink and an electrophoretic electrode which is located on the side opposite to the discharge section in the ink chamber and concentrates the toner on the discharge section by an electrophoretic phenomenon. The ink storage unit includes a circulating unit that communicates the ink chamber with the ink storage unit via a conduit and circulates the ink by a pump. At both ends of the ejection electrodes 3 of the recording head 1 (arrangement direction), the distance from the ejection electrodes 3 on each end side to the recording paper 5 is measured by measuring the distance to a recording sheet (recording medium) 5 described later, which is located in the ejection direction. (Recording gap measuring means) 7 for relatively measuring the recording gap 6 up to the above. The sensor 7 is connected to the control unit 8 (see FIG. 3), and the measurement result is sent to the control unit 8 and processed.

The above-described counter electrode 2 is located in front of the recording head 1 in the ejection direction, and rollers 10 for transporting the recording paper 5 are provided on both sides of the counter electrode 2. Since the roller 10 is located farther than the counter electrode 2 when viewed from the recording head 1, tension is applied to the recording sheet 5 sent between the counter electrode 2 and the recording head 1 by the roller 10, and the recording sheet 5 can be brought into close contact with the counter electrode 2. The counter electrode 2 is finely rotated around an axis along the spacing direction of the recording head 1 by a θ rotation mechanism (not shown) in the θ rotation direction, and is shown around an axis along the arrangement direction of the ejection electrodes 3, ie, in the φ rotation direction. It is finely rotated by a rotating mechanism. Beside the counter electrode 2 is a heater 11 for fixing toner. Since the heater 11 also needs to be in close contact with the recording paper 5, the counter electrode 2 and the heater 11 move slightly in each rotation direction as a unit.

FIG. 3 is an explanatory diagram of a correction operation by adjusting the recording gap 6 according to the present invention. This will be described below with reference to FIG. First, when the recording paper 5 is fed in the direction of arrow H in the drawing along the arrangement direction of the ejection electrodes 3 in the recording head 1, the recording head 1 is positioned at one end of the spacing area 4 before the start of the recording operation, Therefore, the recording gaps 6 at the points A and B are measured by the sensors 7 at both ends. Next, the recording head 1 is spaced to the other end of the spacing area 4, where the recording gap 6 at the point C and the point D is measured again. Based on the four points measured as described above, the control unit 8 performs, for example,
The counter electrode 2 is finely moved by controlling the θ rotation mechanism and the φ rotation mechanism (not shown) so that the recording gap 6 from each discharge electrode 3 to the recording paper 1 is always constant during the recording operation, and the counter electrode 2 is slightly moved to rotate in the θ rotation direction and φ rotation. The direction is corrected. Here, the measured values at the points A, B, C, and D are respectively represented by Da,
Assuming that Db, Dc, and Dd, the correction angle θ in the θ rotation direction and the correction angle φ in the φ rotation direction can be estimated by, for example, the following equations (2) and (3). θ = K1 * ((Db−Da) / 2 + (Dd−Dc) / 2) / 2 (2) φ = K2 * ((Dc−Da) / 2 + (Dd−Db) / 2) / 2 (3) Here, K1 and K2 are conversion coefficients from the correction value to the correction angle. However, the above formula is an example for estimating the correction amount, and the calculation formula of the correction amount is not specified. Although the number of measurement points is four in the text, correction is possible if there are at least three measurement points. Instead of finely moving the opposing electrode 2 as described above, the recording head 1, that is, the ejection electrode 3 may be finely moved.

FIG. 4 is an explanatory diagram of a correction operation based on a change in recording voltage according to the present invention. This will be described below with reference to FIG. First, when the recording paper 5 is fed, before the start of the recording operation, the recording head 1 is located at one end of the spacing area 4, where the sensors 3 at both ends detect the points A and B.
The recording gap 6 at the point is measured. Next, the recording head 1 spaces up to the other end of the spacing area 4, where the recording gap 6 at the point C and the point D is measured again.
Based on the four points measured above, the control unit 8 performs control to change the voltage applied to the ejection electrode 3 according to the size of the recording gap 6 so as to be optimal during the recording operation.
This is performed in a subsequent recording operation. That is, A, B,
When the recording gap 6 at each point of C and D is measured, the recording voltage at each point is determined by a conversion table or a conversion formula prepared in advance based on the measured values. In this case, the recording voltages at point A are Va, the recording voltage at point B is Vb, the recording voltage at point C is Vc, D
Assuming that the recording voltage at the point is Vd, the recording gap at the point A is Da, the recording gap at the point B is Db, the recording gap at the point C is Dc, and the recording gap at the point D is Dd, Va = f1 (Da), Vb = f2 (Db), Vc
= F3 (Dc), Vd = f4 (Dd), where the coordinates of point A are (0,0) and the coordinates of point B are (0,0,
Y), the coordinates of point C are (X, 0), and the coordinates of point D are (X, Y), and any point (x,
The recording voltage V (x, y) in y) is given by the following equation (4).
~ Can be estimated by equation (8).

V (x, y) = K3 * Va + (α1 + (α2-α1) / Y * y) * x + K4 * (β1 + (β2-β1) / x) * y (4) α1 = (Vc−Va) ) / X (5) α2 = (Vd−Vb) / X (6) β1 = (Vc−Va) / Y (7) β2 = (Vd−Vb) / Y (8) where K3 , K4 are correction coefficients. The above equation is an example for estimating the recording voltage, and the equation for calculating the recording voltage is not specified. The number of measurement points is four in the text, but if there are at least three measurement points, the recording voltage can be estimated.

In the above, when the recording gap 6 is measured, the control unit 8 uses the conversion table or the conversion formula prepared in advance based on the measured value to optimize the migration during the recording operation. Control for changing the voltage applied to the electrode may be further performed during the recording operation.

The above-mentioned electrostatic ink jet recording apparatus comprises:
Since sensors 7 for measuring the recording gap 6 up to the recording paper 5 are provided at both ends of the row of the ejection electrodes 3 of the recording head 1, the recording gap 6 between each ejection electrode 3 and the recording paper 5 is provided.
Can be always kept constant during the recording operation, or the recording voltage can be changed in accordance with the size of the recording gap 6 during the recording operation to always provide the optimum recording voltage. The ejection performance can be equalized, and the recording quality can be stabilized in the entire spacing area 4. Therefore, a high-quality and high-reliability recording apparatus that does not have recording unevenness and does not cause performance deterioration due to a deviation of the recording gap even when used for a long time.

[0019]

As described above, the electrostatic ink jet recording apparatus of the present invention has recording gap measuring means for measuring the recording gap up to the recording medium at both ends of the discharge electrode array of the head. A high-quality, high-reliability recording apparatus that can equalize the ejection performance at all recording points during operation, and thus has no recording unevenness and does not cause performance degradation due to a deviation of the recording gap even when used for a long time. Become.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a recording unit of an electrostatic ink jet recording apparatus according to the present invention.

FIG. 2 is an enlarged view taken in the direction of arrow F in FIG.

FIG. 3 is a diagram illustrating a correction operation by adjusting a recording gap of the electrostatic inkjet recording apparatus of the present invention.

FIG. 4 is a diagram illustrating a correction operation based on a change in recording voltage of the electrostatic ink jet recording apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Counter electrode 3 Counter electrode 4 Spacing area 5 Recording paper 6 Recording gap 7 Sensor (recording gap measuring means) 8 Control part 10 Roller 11 Heater

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Mizoguchi Niigata Prefecture Kashiwazaki-shi, 7546 Yasuda, Niigata Nippon Electric Co., Ltd. (72) Inventor Junichi Suetsugu 746 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric ( 72) Inventor Hitoshi Takemoto 7546 Yasuda, Kashiwazaki City, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (72) Inventor Kazuo Shima 7546 Yasuda Oji, Kashiwazaki City, Niigata Prefecture Niigata Nippon Electric Co., Ltd. 7546 Yasuda, Kashiwazaki, Niigata, Japan

Claims (5)

[Claims] 1. A head having a discharge section capable of discharging insulating ink containing charged toner to the outside, and a recording medium disposed on the head side while being disposed opposite to the discharge section of the head. A recording medium by discharging the toner in the ink in the direction of the counter electrode from the discharge portion by a potential difference that is provided in a plurality of electrodes and a plurality of electrodes on the counter electrode side of the head in a pulsed manner and is instantaneously applied by applying a pulse voltage; And a discharge gap measuring means for measuring a print gap to a recording medium at both ends of the discharge electrode array of the head. An electrostatic ink jet recording device. 2. The recording gap measuring means measures a recording gap at three or more different positions by performing a spacing operation of moving the head along a counter electrode before starting a recording operation. Claim 1
The electrostatic ink jet recording apparatus as described in the above. 3. The electrostatic ink jet recording apparatus according to claim 2, wherein the two recording gap measuring units respectively measure the recording gaps at both ends in a spacing direction. 4. The static electricity storage device according to claim 1, further comprising a control unit configured to finely move the counter electrode or the ejection electrode based on a measurement result obtained by the recording gap measurement unit. Electric inkjet recording device. 5. The apparatus according to claim 1, further comprising a control unit that changes a voltage applied to the ejection electrode based on a measurement result obtained by the recording gap measurement unit. An electrostatic ink jet recording device.