JPH0280947A - Method for measuring coefficient of induction of previous droplet in ink jet printer - Google Patents

Abstract

PURPOSE:To accurately measure the coefficient of induction of a previous droplet by a method wherein charge is applied to an ink droplet using a predetermined coefficient of induction of a previous droplet while the ink droplet is allow to fly in a predetermined pattern and a noticeable droplet is caught to measure charge quantity and the coefficient of induction of a previous droplet is adequately altered to be compared with a measured value. CONSTITUTION:In an ink droplet forming device 1, ink is introduced into an internal ink flow passage 4 by driving a pump and emitted in a columnar shape from a nozzle 5. When an ink droplet D is separated from the ink column 8, the charge proportional to the voltage applied to a charge electrode 6 and having polarity reverse to that of said voltage is applied to the ink droplet D and the ink droplet D is deflected by the electric field formed by a deflection electrode 7 to fly. This ink droplet D collides with a charge detecting gutter 11 and the weak current flowing to the gutter 11 is detected by a charge current detector 12 and a CPU 13 receives the detection value from the detector to generate charge voltage in a charge voltage generating circuit 14 and controls the charge quantity of the electrode 6 to perform control following the detection of the coefficient of induction of a previous droplet. The CPU 13 alters the coefficient of induction of a previous droplet appropriately to compare the same with a measured value and accurately calculates the coefficient of induction of an ink droplet.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention continuously jets ink droplets, charges these ink droplets according to an image signal, and deflects them according to the band lit to create an image. A method and apparatus for measuring the influence of an already charged ink droplet on the charge of a subsequent ink droplet in an inkjet printer that performs recording, and for measuring a preceding droplet induction coefficient that quantifies the influence. It is something that comes together.

[Prior Art 1] The above inkjet printer includes the following 1. As shown in FIG. 6, a large number of nozzles 51 are formed along the longitudinal direction of the ink droplet generator
．． From 51..., ink is ejected in a columnar manner. that time,
Vibration is applied to the ink column 52 by a vibrator (not shown) provided in the ink droplet generator 50, and the ink column 52 is
is separated into droplets and sent flying as ink droplets.

A charging electrode 53 is provided in front of the ink droplet generator 50 for charging ink droplets according to an image signal, and separation of the ink column 52 into ink droplets is performed by the charging electrode 5.
3, and is carried out on the entrance side. A voltage corresponding to an image signal is applied to the charging electrode 53 when the ink column 52 is separated into ink droplets. Since the ink has conductivity and the ink column 52 is in contact with the ink droplet generator 50 connected to ground, charge is transferred to the ink column 52 via the ink droplet generator 50. When the ink drips are separated from the ink column 52, the charged electrode 5
3 is charged with a charge that is proportional to the magnitude of the voltage applied to it and has an opposite polarity.

Thereafter, this ink droplet is deflected according to the amount of charge by an electric field created by a deflection electrode 54 provided in front of the charging electrode 53, and flies onto recording paper (not shown) to print an image. It became like that.

There is.

However, the above inkjet printer has the following problems when charging the ink ID in accordance with an image signal. That is, as shown in FIG. 7, the ink droplet is separated from the ink column 52 inside the charging electrode 53, and at the moment of separation, it is charged according to the electric field created by the charged N electrode 53. At this time, there is already charged ink IDDD (hereinafter referred to as drip-proof) in front of the ink ID□ newly charged by the charging electrode 53 (the subscripts -1, -2, -3 are The ink drips 1 drop, 2 drops, and 3 drops before the ink drop of interest are shown.) Therefore, when a new ink droplet is charged by the electric field created by the charging electrode 53, the charges of the previously charged previous W4D-1, D-2, and 0-3 are applied to the subsequent ink droplet. Even if a predetermined voltage is applied to the charging electrode 53, the ink drips. However, there is a problem in that charging distortion occurs in which a predetermined charge is not charged.

For example, as shown in FIG. 8, a voltage of 100 V is applied to the charging electrode 53 to collect the first ink droplet Do, and then the ink droplet Do is charged. i
ID. 11 corresponding to +100V, and the subsequent ink droplets D, D2, D3 are not charged by applying voltage to the charging electrode 53. -15V, -6V, -
A corresponding charge such as 2V will be charged due to the pre-drop induction effect. This pre-drop guiding effect also affects the ink dripping after the fourth drop, but the effect is so small that it can be ignored.

As described above, even if a predetermined voltage is applied to the charging electrode 53, it is not possible to charge the ink droplets with a predetermined charge due to charging distortion caused by the pre-drop induction effect. Therefore,
When the ink droplets are deflected by the deflection electrode 54, since the ink droplets are not charged to a predetermined charge, they are deflected in a direction different from the direction in which they should originally be deflected, making it impossible to accurately print a predetermined image. There was a problem.

By the way, as a theoretical analysis of the above-mentioned predrop induction effect,
j I BM journal or research
ch and development Vol. 2
1. No. There is something described on page 38 of IJ. According to equation (6) in P38, Q = CVo-αQ-1-βQ-2-γQ-3(I) holds true (however, since the polarity of vo is different from this case, the Cvo term is ).

Here, Q is attention dripping. The amount of charge actually charged on
C shows the charging electrode 53 and ink dripping. The capacitance between ■ is the noteworthy drip. The voltage Q applied to the charge quantity electrode 53 to charge the voltage is the voltage drop. , Q-2 is the charge amount of the ink droplet D-1 two drops before the noted droplet D0, Q-3 is the ink droplet three drops before the noted droplet Do, The charge amounts, α, β, and γ are the charges of the ink drop DDD 1 drop, 2 drops, and 3 drops before the target drop, respectively. The front droplet induction coefficient indicates the magnitude of the front droplet induction effect given to the charging of -1'-2'-3.

If there is no foredrop induction effect, the foredrop induction coefficient α,
The values of β and γ are O, and Qo=CV.

A relationship is established.

Therefore, it drips with attention. The charge charged on the charging electrode 5
Voltage V applied to 3. Determined by .

However, in reality, it has a pre-droplet inducing effect, so it draws attention to the drip. will be charged with the charge given by formula (I).

Divide both sides of the above (I> formula by C to obtain Q /C = Vo - αQ, / C - βQ, / C〇1 γQ - 3 / C (II>. Here, the relationship Q = CV Since (I
F) Formula can be expressed as follows.

v −=v −(2V = −βV, −γv.

(I[I) Here, ■ is an attention drop as mentioned above. is the voltage applied to the charging electrode 53 to charge v −+V−
IZV-2ZV-3-IL attention dripping. .

Convert the actual charge amount of DDD to voltage = 1・-2+
-3 It's Tachino. That is, if there is no predrop inducing effect, V' would be V, as stated earlier. matches.

Therefore, in order to charge the target droplet Do with a predetermined charge, taking into account the pre-drop induction effect, v = v ''-+
−av′+βV −+rV, −3(rV) The voltage V given by. It is sufficient to apply this to the charging electrode 53.

Therefore, by measuring the pre-droplet induction coefficients α, β, and γ in advance and correcting the voltage applied to the charging electrode 53 according to equation (IV), all ink droplets are charged with a predetermined charge. It is possible to print images accurately.

Conventionally, the following methods have been proposed for measuring the leading droplet induction coefficients α, β, and γ (Sharp Technical Report, July 1983, No. 23, "Print Distortion in Inkjet Printers"). Analysis J p p 50-51 appendix (2)) This method is called the free beam method, and as shown in Figure 9, one ink droplet is charged and deflected with, for example, +50V, and the subsequent The ink drips are
Even when the ink droplet is not charged, an extra charge of the opposite polarity is induced in the subsequently charged ink droplet due to the pre-droplet induction effect, and the ink droplet is deflected in the opposite direction despite being charged at OV.

Therefore, as shown in Figure 10, α and β of equation (IV)
, γ are adjusted to charge the voltage with α, β, and γ correction, and when the deflection amount of the subsequent ink droplet becomes O, that is, when the preceding droplet guidance effect is corrected. α, β
, γ are determined as accurate foredrop induction coefficients.

[Problems to be Solved by the Invention] However, the above prior art has the following problems. That is, this method uses the predrop induction coefficient α,
By changing β and γ variously to charge an ink droplet, making the ink droplet fly in that state, and actually detecting the change in the flying direction of the ink droplet, we can calculate the pre-droplet induction coefficient α
, β, and γ. However, in addition to the charging distortion due to the pre-drop induction effect, the aerodynamic influence and Coulomb force exerted by nearby ink droplets during the flight of the ink droplet are simultaneously acting on the ink droplet.

Therefore, even if the ink droplet flies in a predetermined direction by changing the leading droplet guidance coefficients α, β, and γ,
Since the aerodynamic influence of nearby ink droplets and the influence of Coulomb force are also acting at the same time, it cannot be concluded that the leading droplet guiding effect has been corrected accurately.

During the flight of the ink droplets, the aerodynamic effects and Coulomb force effects exerted by neighboring ink droplets vary depending on the flight pattern of the continuously flying ink droplets.

Therefore, since the drip-proof corrosion conductivity coefficients α, β, and γ determined by the above-mentioned free beam method include the amount of distortion that depends on the charge amount and flight pattern of the ink drip, the pre-droplet induction coefficient α
, β, and γ cannot be measured accurately.

[Means for Solving the Problems] Therefore, the present invention was made to solve the problems of the prior art described above, and its purpose is to actually fly ink droplets and Even when measuring the droplet induction coefficient, by directly measuring the amount of charge on the ink droplet, it is possible to accurately determine the droplet induction coefficient without being influenced by aerodynamic effects or Coulombic forces exerted by surrounding ink droplets. An object of the present invention is to provide a method and apparatus for measuring the predroplet induction coefficient, which can measure the predroplet induction coefficient.

That is, in the method for measuring a front droplet induction coefficient in an inkjet printer according to the present invention, ink droplets are continuously ejected from a nozzle, and while these ink droplets are charged according to an image signal, they are deflected according to the amount of charge. This is a method for measuring the coefficient of the pre-drop induction effect that an already charged ink droplet has on the charge of a subsequent ink droplet in an inkjet printer that records an image using a predetermined pattern. At the same time, the ink droplet of interest is charged with an electric charge using a predetermined pre-droplet induction coefficient, and the amount of charge of the ink droplet of interest is measured as a first measurement value by capturing the droplet of interest. , while making ink droplets fly in different patterns, the ink droplet of interest is charged using a predetermined pre-droplet induction coefficient so that it has the same amount of charge as above, and the amount of charge of this ink droplet of interest is determined by the amount of charge of the ink droplet of interest. The pre-drop induction coefficient is measured by capturing a second measurement value and comparing the first measurement value and the second measurement value.

In addition, the measuring device according to the present invention uses an inkjet that records an image by continuously ejecting ink droplets from a nozzle, charging these ink droplets according to an image signal, and deflecting them according to the amount of charge. In a printer, a device for measuring the coefficient of the pre-drop induction effect that an already charged ink droplet has on the charge of a subsequent ink droplet, the charging device charging a predetermined charge to successively ejected ink droplets. means for detecting the amount of charge by capturing a flying ink droplet charged with a predetermined charge; Each droplet of interest is charged with a voltage calculated using a predetermined pre-droplet induction coefficient, and at that time, the charge m of each droplet of interest is detected by the charge amount detection means.
and a control means for performing an operation of comparing the pre-drop induction coefficient and measuring the pre-droplet induction coefficient.

[Operation] In the measuring method according to the present invention, ink droplets are continuously ejected from a nozzle, and these ink droplets are charged and caused to fly in a predetermined pattern. At this time, the ink droplet of interest is charged with a predetermined charge using a predetermined pre-drop induction coefficient. Then, the band Nfli of this ink droplet of interest is measured by capturing the ink droplet of interest, and the first
be the measured value. Next, the ink droplets are made to fly in different patterns, and the ink droplet of interest is charged using a predetermined front induction coefficient to form the same charged image as above, and the amount of charge of the ink droplet of interest is determined as follows: A second measurement value is obtained by capturing the droplet of interest. Then, these first measurement values and second measurement values are compared. if,
If the front induction coefficient is an accurate value, the first measured value and the second measured value will be equal. Therefore, the above operation
Measure the exact iyJ droplet induction coefficient while correcting the front induction coefficient until the first and second measurements are equal.

In the measuring device according to the present invention, the ink droplets continuously ejected from the nozzle are charged by the charging means and are caused to fly in a predetermined pattern. At this time, the ink droplet of interest is charged with a predetermined charge using a predetermined front induction coefficient.

Then, the amount of charge of the ink droplet of interest is detected by capturing the droplet of interest using a charge amount detection means, and the first ink droplet is detected.
be the measured value. Next, while ink droplets are made to fly in different patterns, the ink droplet of interest is charged using a predetermined front induction coefficient so that it has the same amount of charge as described above, and the amount of charge of this ink droplet of interest is determined by A second measurement value is obtained by capturing the droplet of interest using the charge amount measuring means. The first measurement value and the second measurement value are then compared by the control means. The control means determines whether the two values are equal or not, and if they are not equal, changes the previously used front induction coefficient and repeats the above operation as the first one.
Repeat until the measured value of and the second measured value are equal. By doing this, an accurate anterior induction coefficient is determined.

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows an embodiment of a front induction coefficient measuring device for an inkjet printer according to the present invention. In the figure, reference numeral 1 denotes an ink droplet generator that generates ink droplets, this ink droplet generator 1 is made of metal, and the ink droplet generator 1 is connected to ground. An ink flow path 4 with a tapered cross section through which ink flows is formed inside the ink droplet generator 1 . Furthermore, a nozzle 5 communicating with the ink flow path 4 is provided in the front surface of the ink droplet generator 1 . Further, in front of the ink droplet generator 1, there is a charging electrode 6 as a charging means for charging ink droplets ejected from the ink ejection nozzle 5, and an ink droplet charged with a predetermined charge by the charging electrode 6. A deflection electrode 7 is provided for deflecting. A high voltage is applied to the deflection electrodes 7 by a power source 9.10, forming an electric field that deflects ink droplets passing between the deflection electrodes 7.

The ink droplet generator 1 introduces ink into an internal ink flow path 4 by driving a pump (not shown), and ejects the ink in a columnar shape from a nozzle 5, as shown in FIG.

At this time, vibration is applied to the ink column 8 ejected from the nozzle 5 by a vibrator (not shown) provided in the ink droplet generator 1, and the ink column 8 is separated into droplets, causing ink droplets to form. It flies as.

As shown in FIG. 2, this separation of the ink column 8 into ink droplets is set to occur inside the charging electrode 6 and near sunset. When the ink column 8 is separated into ink drops, a predetermined voltage is applied to the band N electrode 6.

The ink has conductivity, and since the ink column 8 is in contact with the ink droplet generator 1 which is connected to ground, electric charge is transferred to the ink column 8 via the ink droplet generator 1, Due to electrostatic induction, when the ink drop is separated from the ink column 8, it is charged with a charge that is proportional to the magnitude of the voltage applied to the charging electrode 6 and has a polarity opposite to that of the voltage. Thereafter, this ink droplet is deflected according to the amount of charge by the electric field created by the deflection electrode 7, and is caused to fly.

In front of the deflection electrode 7, as shown in FIG. 1, a gutter 11 is provided as a charge amount detection means at a position where the ink droplets are not deflected but go straight. The gutter 11 for detecting the amount of band N is formed by bending a thin metal plate into a cross-section of a square shape, and has an opening 11a facing the ink droplet generator 1. The charge amount detection gutter 11 has a charge current detection device 12 capable of detecting minute currents.
The ink dripping is connected to the gutter 1 for detecting the amount of charge.
A charging current detection device 12 detects a minute current flowing through the gutter 11 due to the collision with the gutter 1 .

The charging current detection device 12 uses a CPU as a control means.
13, and this CPU 13 is connected to a charging voltage generation circuit 14 that applies a predetermined voltage to the charging electrode 6. The CPU 13 includes a charging voltage generation circuit 14
It has a function of sending a signal to and controlling the amount of charge of the ink MD by the charging electrode 6. Further, the CPU 13 performs various controls associated with the detection of the front induction coefficients α, β, and γ.

At this time, the CPU 13 calculates predetermined front induction coefficients α, β, and γ based on equation (IV) for the ink droplet of interest whose charging current is detected by the charging amount detection gutter 11.
A charging voltage corrected using the above is applied to the charging electrode 6, and charging is controlled so that the ink droplet of interest is charged with a predetermined charge.

Although predetermined values are stored in the memory in advance as the front section induction coefficients α, β, and γ, the CPU 13 changes these surface section induction coefficients α, β, and γ as necessary, so that (
rV).

In Figure 1, 15 indicates a gutter for collecting unnecessary ink droplets;
Reference numeral 6 indicates a large gutter that collects ink droplets that are not collected by the charge amount detection gutter 11 or the gutter 15, respectively.

In the above configuration, based on the operation of the measuring device,
Front W4 in the inkjet printer according to this invention
The method for measuring the induction coefficient will be explained. First, a method for measuring the front induction coefficient α will be explained. That is, the CPU
13 sets the value of the front induction coefficient α to a predetermined initial value based on the numerical value stored in a memory (not shown) (step 1). Next, CPU 1
3 applies a voltage to the charging electrode 6 in a predetermined charging pattern via the charging voltage generating circuit 14, and as shown in FIG. The drippings are charged and deflected by the electric field created by the deflection type 1fi7, causing them to fly (step 2).

At this time, the CPU 13 applies correction to the charging electrode 6 via the charging voltage generation circuit 14 based on the formula (rV) using predetermined front induction coefficients α, β, and γ, and prevents ink dripping. The ink dripping is charged at -50V and attracts attention. is charged so that the amount of charge becomes O.

Then, the ink dripping charged with -50V is applied to the gutter 1.
Ink drips collected and noted in step 5. is charged so that the amount of charge is O, so it moves straight, collides with the charge amount detection gutter 11 and is captured, and its charge ω is detected by the charging current detection device 12 (step 3). cpu
i3 stores the current value 11 detected by this band'Fi current detection device 12 as a first detected value.

Next, as shown in FIG. 5, the CPU 13 follows the same flight pattern as above, but with a drop of attention. The ink droplet is charged so that the ink droplet [)-1 one drop before is charged with +50V (step 4). And attention dripping. is captured by the charge amount detection gutter 11, and the charge amount is detected by the charging current detection device 12 (step 5). C
The PU 13 stores the current value I2 detected by the band Ti current detection device 12 as a second detected value.

The CPU 13 determines whether the absolute value of the difference between the current value I and the current value 12 is smaller than a predetermined value M (step 6). In this case, since M is set to a value sufficiently close to 0, it is ultimately determined whether the current value 11 and the current value I2 are approximately equal.

If it drips with attention. When charging, if the correct value of the front induction coefficient α is set and corrected, the attention drips. 1
Ink drips before the drop, regardless of the amount of charge. Since the amount of charge should not change, [ = 12.

The CPU 13 determines whether or not the difference between the current value ■1 and the current value I2 is smaller than a predetermined value M. If it is not smaller, the CPU 13 slightly changes the front induction coefficient α (step 7).
), repeat the same operations as above (steps 2 to 6).

That is, for the -th measurement, the following relationship holds true based on the equation (rV).

v = v ′+αV −1βv−2+γv−3(
v) Here, Vol is attention dripping. The voltage applied to the charging electrode 6 when charging is V. 1' represents the amount of charge actually charged on the target droplet D0 in terms of voltage, and both are given the subscript 1 indicating that they are the first value.

Next, for the second measurement, the above (I
V) According to the equation, the following relationship holds true.

V =V −−+−αso −+βV−2+
TV.

(Vr) Here, Vo2 is the same as above, dripping with attention. vo2 is the voltage applied to the charging electrode 6 when charging.

It is expressed in voltage as the actual electrically charged electric bond.
A subscript 2 is attached to both values to indicate that they are the second values. Now, the voltage display V1 of the charging 8 of the ink droplet [)-1, which is one drop before the noted droplet DO, is different from the first time, so it is displayed with the subscript 2.

Taking the difference between both sides of (V) and (Vl) above, we get v
-v =v "-vo2'"+α(v-11-V
−) is (q).

A drip of ink to watch out for. When the amount of charge becomes equal, that is, when the current value 11 and the current value r2 become equal, V'-vo2-, so V -V -α
(V − −V −), α−(V −V )/(V ′−V −)
The following relationship holds true: (VN).

Furthermore, V- and V-- are similarly represented by formula (III) as follows.

v −=v −αV −−βv−31V−4
1 ■-12""-12-(xv-22-1βv-32-T
V-42 (■) Here, when comparing Figures 4 and 5, D-2゜DD
The amount of charge is common throughout both figures.
4, the following formula holds.

V=v-22 V, 1 = V, 2'' (rX)v-
■-42 Therefore, from equations (■) and (rX), V − − V = 1
2' is expressed as follows.

V −V−−=■−1. −V, (X) Below, the following formula is obtained from formula (■) and formula (X).

α-(V-V)/(V-V)(X
I) That is, the value of the front induction coefficient α when the detected value ■ and 12 become equal is uniquely determined by the equation (XI), and this becomes the accurate front induction coefficient α.

Next, the CPU 13 sets the accurate value of the droplet guidance coefficient α measured as described above, and also sets the value of the droplet guidance coefficient α in the memory (
The value of #i droplet induction coefficient β is set to a predetermined initial value based on the numerical value stored in (not shown) (step 8). Next, the CPU 13 applies a voltage in a predetermined charging pattern to the charging electrode 6 via the charging voltage generating circuit 14 as described above, and as shown in FIG.
The ink droplets that are continuously ejected are charged and deflected by the electric field created by the deflection electrode 7, causing them to fly (step 9).

At this time, the CPU 13 applies the charge voltage generation circuit 14 to the charge N electrode 6 while correcting the ink droplets using predetermined front induction coefficients α, β, and γ based on the equation (IV). Charge it with -50V and notice the ink dripping. is charged so that the amount of charge becomes O.

Then, the ink dripping charged with -50V is applied to the gutter 1.
Ink drips collected and noted in step 5. is charged so that the amount of charge is 0, so it moves straight, collides with the strip 1ffill detection gutter 11 and is captured, and the amount of charge is detected by the charging current detection device 12 (step 10).
, the CPU 13 stores the current value ■1 detected by the charging current detection device 12 as a first detected value.

Next, the CPU 13 has the same flight pattern as above, but with a drop of attention. The ink drops are charged so that the ink ID-1 two drops before is charged with +50V (Step 1
1). And attention dripping. is captured by the charge amount detection gutter 11, and its charging port is detected by the charging current detection device 12 (step 12). The CPU 13 converts the current value I2 detected by the charging current detection device 12 into
It is stored as the second detected value.

The CPU 13 determines whether the absolute value of the difference between the current value 11 and the current value I2 is smaller than a predetermined value M (step 13).

The CPU 13 determines whether the absolute value of the difference between the current value I and the current value I2 is smaller than a predetermined value M, and if it is not smaller, slightly changes the front layer induction coefficient β (step 14). ), repeat the same operation as above (step 9~
13).

Then, in the same manner as above, calculate the front layer induction coefficient β, set the values of the calculated front layer induction coefficients α and β, and
The front layer induction coefficient γ is set (step 15), and the same operation as above is repeated to measure the accurate value of the front layer induction coefficient γ. At that time, the flying pattern of ink drops is as follows:
Dripping attention. Measurement is performed by changing only the charging voltage of the ink drop three drops before .

In this way, the ink drops are made to fly in a predetermined flying pattern, and the ink drops are noticed. Only the charging voltage of the ink drop affected by the front induction coefficient is changed sequentially, such as only one drop before, only two drops before, and so on. is actually captured and its charge amount is detected, and the values of the front wA induction coefficients α, β, and γ where the charge ω of the target W4Do does not change even if the charging voltage of the front part DDD of the target droplet D is changed are as follows: It is measured as the true anterior layer induction coefficient. Therefore, it drips with attention. Since we are actually detecting the charging port and determining the values of the front layer induction coefficients α, β, and γ, it is important to pay attention to this. Even if the influence of air force or Coulomb force of surrounding ink drips acts on it, it will not cause noticeable drips. Since only the front induction effect affects the amount of charge, the coefficients α, β, and γ of the front induction effect can be accurately measured.

[Effects of the Invention] The method for measuring the front layer induction coefficient according to the present invention captures an ink droplet of interest and directly measures its band N. Since the front layer induction coefficient is measured as the true value when it is not affected by changes in the droplet band N amount, it is not affected by the aerodynamic influence of surrounding ink droplets or Coulomb force, and is accurately measured. The front layer induction coefficient of an ink drop can be measured.

Further, according to the apparatus for measuring the leading layer induction coefficient according to the present invention, it is possible to provide an apparatus that can automatically measure the leading droplet guiding coefficient accurately as described above.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a measuring device for a front layer induction coefficient in an inkjet printer according to the present invention, and FIG. 2 is an explanatory diagram showing the charging state of an ink droplet at a charging electrode.
FIG. 3 is a flowchart showing the operation of the apparatus shown in FIG. 1, FIGS. 4 and 5 are explanatory diagrams showing different flight states of ink droplets, FIG. 6 is a configuration diagram showing an inkjet printer, and FIG. 7 is an explanatory diagram showing the charging state of an ink droplet at a charging electrode, FIG. 8 is an explanatory diagram showing the front induction effect, and FIGS. 9 and 10 are diagrams of an ink droplet showing a conventional method for measuring the front layer induction coefficient. FIG. 6 is an explanatory diagram showing different flight states. [Explanation of symbols] 5... Nozzle 6... Charging electrode 7... Deflection electrode 11... Gutter for detecting the amount of charge 13... CPU D... Ink droplet Patent applicant Fuji Xerox Co., Ltd. Company representative Patent attorney Tomohiro Nakamura (3 others) Figure 4 Funeral map Figure 4

Claims (3)

[Claims] (1) In an inkjet printer that records an image by continuously ejecting ink droplets from a nozzle, charging these ink droplets according to an image signal, and deflecting them according to the amount of charge, A method for measuring the coefficient of the pre-droplet induction effect that an ink droplet has on the charging of a subsequent ink droplet, the method involves applying a predetermined pre-droplet induction coefficient to an ink droplet of interest while flying ink droplets in a predetermined pattern. The amount of charge on the ink droplet of interest is determined by
The first measurement value is measured by capturing the droplet of interest, and then the ink droplets are ejected in different patterns while
The ink droplet of interest is charged using a predetermined pre-drop induction coefficient to have the same amount of charge as described above, and the amount of charge of the ink droplet of interest is measured by capturing the droplet of interest to perform a second measurement. A method for measuring a leading droplet guiding coefficient in an inkjet printer, characterized in that the leading droplet guiding coefficient is measured by comparing the first measured value and the second measured value. (2) When measuring the preceding droplet guidance coefficient, only the flight pattern of the ink droplet one drop before the ink droplet of interest is changed, the guidance coefficient of the ink droplet one drop before the target ink droplet is determined, and then the ink droplet of interest is measured. By changing only the flight pattern of the ink droplet two drops before the ink drop and finding the induction coefficient of the ink drop two drops before, the previous ink drop can be changed in the order of one drop before, two drops before, three drops before, and so on. 2. A method for measuring a pre-droplet guidance coefficient in an inkjet printer according to claim 1, further comprising measuring a droplet guidance coefficient. (3) Inkjet printers record images by continuously ejecting ink droplets from a nozzle, charging these ink droplets according to an image signal, and deflecting them according to the amount of charge. A device for measuring a coefficient of a pre-droplet induction effect that an ink droplet has on the charging of a subsequent ink droplet, the device comprising: a charging means for charging successively ejected ink droplets with a predetermined charge; a charge amount detection means for detecting the amount of charge by capturing a charged and flying ink droplet; control means for performing an operation of measuring the induction coefficient of the previous droplet by charging it with a voltage calculated using the induction coefficient and comparing the amount of charge of each of the droplets of interest detected by the charge amount detection means at that time; A device for measuring a front droplet induction coefficient in an inkjet printer, characterized by comprising: