JPS63102951A - Stitching device of ink jet printer - Google Patents

Abstract

PURPOSE:To make an ink jet printer small in size at least in the width's direction of a recording paper, by a method wherein a plurality of drop sensors are spaced a predetermined distance away from respective actual stitch points on the side of a nozzle or on the opposite side of the nozzle. CONSTITUTION:Drop sensors 1 are disposed alternatively on positions 15 spaces a predetermined distance L1 away from stitch points 6 on a recording paper 7 on the side of a nozzle 100 or on positions 16 spaced a predetermined distance L2 away on the opposite side of the nozzle 100. From the charge voltage of an ink drop 9 when the ink drop 9 passes through the drop sensor 1, the charge voltage of the ink drop 9 when the ink drop 9 passes through the actual stitch point 6 is arithmetically obtained. In this manner, stitching can be conducted without disposing projectedly the drop sensor 1 at one end portion of the recording paper 7, which enables the stitching device as well as the ink jet printer to be made small in size at least in the width's direction of the recording paper 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a stitching device for an inkjet printer, and in particular, to a stitching device for an inkjet printer, and in particular, a stitching device for inkjet printers that directs ink drops ejected from a droplet generator to reach stitching points on recording paper. The present invention relates to a stitching device for an inkjet printer suitable for detecting the charging voltage of an ink drop necessary to control the ink drop, or the electric field control voltage for controlling the electric field of the flight path of the ink drop.

(Prior Art) FIG. 6 is a schematic plan view of a conventional charge control type (charge control type) inkjet printer.

In the figure, an ink droplet ejected from a nozzle of a droplet generating device 5 passes between a pair of charging electrodes 4 and a pair of deflection electrodes 3 arranged in front of the nozzle, as shown by reference numeral 2. and adheres to the recording paper 7. The charging electrode 4 charges the ink drop according to image information. Then, when the ink drop passes between the deflection electrodes 3, it is deflected according to the amount of charge.

By the way, in an inkjet printer equipped with multiple nozzles like this, if the printing area for each nozzle is not set correctly, printing may be omitted or overlapped.
This will significantly deteriorate print quality.

Therefore, conventionally, when an ink drop passes the boundary point (hereinafter referred to as a stitch point) between the printing areas of adjacent nozzles, the charging voltage of the ink drop is calculated, and from this, the printing area of each nozzle can be determined. Techniques for good settings have been proposed.

This setting of the printing area of each nozzle is called stitching.

However, as shown in FIG. 6, since the stitch point 6 is a point on the recording paper 7, an ink drop detection sensor (hereinafter referred to as a drop sensor) is attached to the stitch point 6.
It is extremely difficult to place directly.

Therefore, in the conventional stitching device, the drop sensors 1 are arranged at the same intervals as the intervals between the stitch points 6 on the recording paper 7 so as to protrude toward one end of the recording paper 7, and the drop sensors 1 are The carriage consisting of the droplet generator 5, the charging electrode 4, and the deflection electrode 3 is moved in the direction of arrow D1 so as to move away from the actual printing position (symbols 3A, 4A, 5A).
), the charging voltage of the ink drop when it passes the stitch point is determined. That is, since the mounting position of the drop sensor 1 is a position corresponding to the stitch point 6 on the recording paper 7, ink drops passing through the mounting position (17) of the drop sensor 1 move the carriage to the actual printing position. When it is returned, it will pass through the stitch point 6 on the recording paper 7.

In this way, the charging voltage on the ink droplet flying from each nozzle when the ink droplet passes the stitch point 6 is determined, and the voltage value of the charging voltage is fed back to the control device of the inkjet printer. , it is possible to perform good printing without missing or overlapping characters.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

As mentioned above, in conventional stitching devices,
Because it is necessary to arrange the drop sensor outside the actual printing area and to move the carriage to correspond to the drop sensor, the inkjet printer has problems at least in the direction perpendicular to the recording paper conveyance direction (main scanning direction). ).

In particular, when the ink ejection nozzles are formed over the entire length of the recording paper in the main scanning direction, the width of the inkjet printer is approximately Double the size.

The present invention has been made to solve the above-mentioned problems.

(Means and operations for solving gap points) In order to solve the above-mentioned problems, the present invention provides that each actual stitch point is separated by a predetermined distance on the nozzle side or on the opposite side to the nozzle side. A plurality of drop sensors are arranged as shown in FIG. At this time, a method was taken to calculate the charging voltage or electric field control voltage of the ink drop. A feature of the present invention is that this allows stitching to be performed without disposing the drop sensor so as to protrude from one end of the recording paper.

(Example) The present invention will be described in detail below with reference to the drawings.

Figure 1 is for explaining the basic technical idea of the present invention.
FIG. 1 is a schematic plan view of a charge-controlled inkjet printer. In FIG. 1, only one nozzle for ejecting ink is shown for the sake of clarity.

In FIG. 1, ink drops ejected from a nozzle 100 of a droplet generating device 5 are charged by a charging electrode 4, deflected by a deflection electrode 3, and attached to a recording paper 7.

The present invention provides a drop sensor at a position 15 that is a predetermined distance L1 away from the stitch point 6 on the recording paper 7 toward the nozzle 100, or at a position 16 that is a predetermined distance L2 away from the nozzle 100. When the ink drop passes through the drop sensor, the charged voltage of the ink drop indicates that the ink drop is at the actual stitch point 6.
This method estimates the charging voltage of the ink drop when it passes through the ink drop.

First, the drop sensor will be explained. FIG. 2 is a schematic perspective view of the drop sensor.

In FIG. 2, the drop sensor is, for example, a-3i
It is composed of a pair of photodetectors 11 and 12 made of a (amorphous silicon) thin film or the like, and illumination means 8 such as an LED for illuminating the photodetectors 11 and 12.

When the photodetecting elements 11 and 12 are irradiated with light, they output a photocurrent depending on the amount of light.

As shown in FIG. 2, when an ink drop 9 flies between the center of the photodetector 11, 12 and the illumination means 8, that is, the center of the drop sensor 1,
Shadows 10 of the same size are formed by the ink drops 9 on the photodetecting elements 11.12, and the difference in the amount of light incident on the photodetecting elements 11°12 or the photodetecting elements 11.12 The difference between the photocurrents outputted is zero.

If the ink drop 9 is shifted from the position shown in FIG. 2 in the arrangement direction of the photodetecting elements 11 and 12 (arrow U direction), the difference in the amount of light incident on the photodetecting elements xi and t2, or The charging current difference has a positive or negative value.

Therefore, if the drop sensor 1 is arranged so that each photodetection element 11.12 is arranged in the nozzle arrangement direction of the inkjet printer or in a direction perpendicular to the flight path of the ink drop, the photodetection elements 11.12. 12
From the difference in the photocurrents, it can be determined whether the ink drop 9 has passed through a predetermined position.

FIG. 3 is a graph showing the relationship between the difference in photocurrent output from a pair of photodetecting elements of a drop sensor and the position of an ink drop in the nozzle arrangement direction. In FIG. 3, a point 2 where the characteristic curve 21 intersects the coordinates of zero photocurrent difference
2 indicates the center position of the drop sensor. Next, as described with reference to FIG. 1, the drop sensor is placed on the nozzle side with a distance of Ll from the stitch point 6 on the recording paper 7, or on the opposite side from the nozzle side with a distance of L2. A method for determining the charging voltage of the ink drop necessary for the ink drop to pass over the actual stitch point 6 will be explained.

FIG. 4 is a schematic plan view of the inkjet printer in which the drop sensor 1 is arranged at a distance from a pair of stitch points 6 on the recording paper 7 on the side opposite to the nozzle side. In FIG. 4, the same reference numerals as in FIG. 1 represent the same or equivalent parts.

In FIG. 4, the point where the locus (broken line 18) of the ink drop passing through one of the drop sensors 1a placed at the position indicated by Z intersects with the recording paper 7 is Ql. At this time, the amount of charge of the ink drop is q. ', the charging voltage is Vl'
shall be.

Further, the charging voltage when the ink drop passes through the other drop sensor 1b is assumed to be V2'.

In addition, the length of the deflection electrode 3 is A, the distance from the end of the deflection electrode 3 to the recording paper 7 is 81, the distance from the recording paper 7 to the drop sensor 1a is defined as m1, and the mass of the ink drop is m1. The speed (constant to simplify the calculation) is ■, and the voltage applied to the deflection electrode 3 is E.
Then, the displacement G1 by which the ink drop is deflected between the deflection electrodes 3 is G 1- (q' E/ 2 m) X (A/v)
2-(1) Furthermore, the displacement G2 by which the ink drop is deflected after passing through the deflection electrode 3 until it reaches the drop sensor 1a or 1b is: G2- (Q' E/mv2)XAX (B+L)・・・
・(2) Next, the distance between one stitch point 6 (P) and the point Q where the ink drop passing through the one drop sensor 1a intersects the recording paper 7 is Y, and the pair of stitch points 6
Let W be the interval between , that is, the deflection width of the ink drop. Also, as shown by the flight path 27, the charging voltage when the ink drop passes through one stitch point 6 (P),
and the charging voltage when passing through the other stitch point 6 are vl, v2 . Also, Vl-V2 is v1Vl'
-V2' is V', (V-V'')/V-
2Y/W- (3) Therefore, V-+W/ (W-2Y)) If the angle between this and the flying path of the uncharged ink drop is θ, then Y = L tanθ - (G2xL)/ (B+L)... (5) Now, from the above equations 1 and 2, Gl/G2- A/ (2x (B+L)l...(6
) Also, since the deflection width of the ink drop is W, G 1
+G 2-W/2...(7) From formulas 6 and 7, Gl-AW/ f2x (A+2B+2L)1...(
8) G2- ((B+L)xWl / (A+2B+2L)...(9) From equations 5 and 9, Y-LW/ (A+2 B+2 L)...(10) Substitute equation 10 into equation 4 Then, V-((A+2B+2L)/(A+28)IX V
/...(11) ,',V1-V2- +(A+2B+2L)/(A+2
B) I
〇...(13) Solving the 12th and 13th equations for Vl and V2, Vl-((A+28+L)/(A+2B))xVl'
-fL/ (A+28)l xV2'=V1'
+ (L/ (A+2B)) x(Vl' -V2
) ...(14)V2-- (L/ (A+
2B)] xV1' + ((A+28+L)/ (
A+2B))×v2'-V2' -(L/ (A+2B)l X(Vl'
-V2') (15) The values of A, B, and L shown in equation 14.15 are determined from the design values of the stitching device, as is clear from FIG.

In this way, with respect to a pair of stitch points, the charging voltages Vl', V2 of an ink drop passing through a pair of drop sensors arranged at a distance L on the opposite side from the nozzle are determined.
If ' is detected, the charged voltages Vl and V2 of the ink drop passing through the pair of stitch points can be calculated from equations 14 and 15.

Alternatively, a pair of drop sensors may be provided at a predetermined distance on the nozzle side for a pair of stitch points, and the charged voltage of the ink drop passing through the drop sensor may be determined. The charging voltages Vl and V2 can be calculated. This method is
It can be easily implemented by those skilled in the art by referring to the above description, so the description thereof will be omitted.

FIG. 5 is a schematic block diagram of one embodiment of the present invention.

In FIG. 5, 1. 2. The same symbols as in Figure 4 are
The same or equivalent parts are hailed.

In addition, in order to make the diagram easier to read, the ink ejecting nozzle,
Also, six drop sensors each consisting of an illumination means 8 and a pair of photodetecting elements are shown. Further, the drop sensor is shown in a front view as seen from the ink drop ejecting direction, and the droplet generator 5, charging power 4, and deflection electrode 3 are shown in a plan view as seen from a direction perpendicular to the ink drop ejecting direction. has been done.

In FIG. 5, lighting means 8 such as an LED, which is arranged at a predetermined distance on the nozzle side or the opposite side to the stitch point of each nozzle, is connected to a switching device 102.
It is connected to the power supply device 103 via. The switching device 102 sequentially turns on each of the lighting means 8 in response to a control signal supplied from the control device 101.

Photodetecting elements 11.12 arranged to face each illumination means 8 are connected to output lines 111A and 112A, respectively. The output lines 111A and 1.12A are
It is connected to the charge current difference detection device 105.

The charge current difference detection device 105 calculates the difference between two input signals, that is, photocurrents output from a pair of photodetector elements 11 and 12 constituting a photodetector, and transmits the result to a control device. Output to 101.

Charging electrodes 4 for charging ink drops flying from nozzles 100 formed in droplet generator 5 are connected to high voltage generators 107, respectively.

The high voltage generator 107 generates a predetermined voltage according to a control signal supplied from the control device 101, and supplies the voltage to a predetermined selected charging electrode 4. This results in
The amount of charge on the ink drop, that is, the amount of deflection changes.

In the switching device having the above configuration, 1. For example, the charging voltage when a flying ink drop ejected from the nozzle 100A passes both stitch points is determined as described below.

First, before printing starts and in a state where the recording paper 7 is not placed in the ink drop flight path, the switching device 102 selects the illumination means 8A, turns on the illumination means 8A, and places the illumination means 8A opposite to the illumination means 8A. Light is irradiated onto the photodetecting elements 11A and 12A arranged in such a manner.

Next, a charging electrode 4A is selected for charging the ink drop ejected from the nozzle 100A, and the ink drop connects the illumination means 8A with the middle of the photodetecting elements 11A and 12A facing the illumination means 8A. The high voltage generator 107 generates a voltage so as to pass on an imaginary line, that is, to pass through the center of the drop sensor.
The charging voltage of the ink drop applied to the charging electrode 4A is adjusted. And the band when the ink drop passes through the center of said drop sensor? [Pressure (V1' when the drop sensor is placed in the direction opposite to the nozzle side from the stitch point) is detected.

Next, the illumination means 8B is selected by the switching device 102, and the illumination means 8B is turned on to irradiate light onto the photodetecting elements 11B and 12B arranged to face the illumination means 8B. Then, the charging voltage of the ink drop applied to the charging electrode 4A is adjusted by the high voltage generator 107 so that the ink drop passes through the center of the drop sensor. Then, the charged voltage (v2' when the drop sensor is disposed in the direction opposite to the nozzle side of the stitch point) when the ink drop passes through the center of the drop sensor is detected.

After that, in the control device 101, if Equation 14.15 is calculated using each of the charging voltages, the nozzle 100A
The charging voltages Vl and V2 when the ink droplets ejected from the stitching points pass through the stitch points are determined.

In one embodiment of the present invention, the charging voltages Vl, V2
is calculated for each nozzle. In the control device of the inkjet printer, each of the charging voltages Vl
, V2 is applied to the charged electrode 4 according to the image information.
The voltage applied to the ink droplet (electrostatic voltage of the ink drop) is adjusted by a known method, and the printing area of each nozzle is set.

As a result, good printing is performed without missing or overlapping characters.

In the above description, it is assumed that the stitching device is applied to a charge control type inkjet printer, but the present invention is not limited to this, and can be applied to an electric field control type inkjet printer. Of course, it may be applied. In this case, instead of determining the charging voltage of the ink drop, the electric field control voltage applied to the deflection electrode for controlling the electric field may be determined.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

That is, by arranging a drop sensor on the nozzle side or on the opposite side to the nozzle side with respect to the actual stitch point on the recording paper, the charge of the ink drop when the ink drop passes the actual stitch point can be adjusted. Since the voltage or electric field control voltage can be determined, there is no need to arrange the drop sensor so as to protrude from one end of the recording paper, as in conventional stitching devices.

Therefore, the stitching device, and eventually the inkjet printer, can be operated at least in the width direction of the recording paper (
(main scanning direction).

[Brief explanation of the drawing]

Figure 1 is for explaining the basic technical idea of the present invention.
Schematic plan view of charge control type inkjet printer, second
The figure is a schematic perspective view of the drop sensor, and Figure 3 shows the difference in photocurrent output from a pair of photodetecting elements of the drop sensor.
A graph showing the relationship between the ink drop and the position in the nozzle arrangement direction; FIG. 4 is a schematic plan view of an inkjet printer in which a drop sensor is arranged on the side opposite to the nozzle side with respect to a pair of stitch points on recording paper; The figure is a schematic block diagram of an embodiment of the present invention, and FIG. 6 is a schematic plan view of a conventional charge control type inkjet printer. 1... Drop sensor, 3... Deflection electrode, 4,4A
... Charged electrode, 5... Droplet generator, 6... Stitch point, 7... Recording paper, 8.8A, 8B... Illumination means, 9... Ink drop, 11, IIA , IIB, 12.12A, 12B...photodetection element, 100,100A...nozzle, 101
...Control device, 102...Switching device, 103...
Power supply device, 105... Charging current difference detection device, 107...
・High voltage generator agent Patent attorney Michito Hiraki and 1 other person Figure 4

Claims (2)

[Claims] (1) A stitching device for an inkjet printer that calculates the charging voltage or electric field control voltage of an ink drop ejected from a nozzle when the ink drop passes through a stitch point, and for each actual stitch point. , a plurality of drop sensors arranged a predetermined distance apart on the nozzle side or the opposite side to the nozzle side, and ink drops ejected from an arbitrary nozzle are provided corresponding to the pair of stitch points. means for detecting a charging voltage or electric field control voltage of the ink drop when passing the drop sensor; and a means for detecting a charging voltage or electric field of the ink drop when the ink drop passes an actual stitch point from the voltage; 1. A stitching device for an inkjet printer, comprising means for calculating a control voltage. (2) The stitching device for an inkjet printer according to claim 1, wherein the drop sensor comprises a pair of photodetecting elements and illumination means for illuminating the photodetecting elements.