JPH03184864A - Method for measuring delivery liquid drop flying speed in ink jet recording head and distance indication member used for said method - Google Patents

Abstract

PURPOSE:To simplify a measuring operation by a construction wherein an indication point which indicates a correctly preset distance is disposed in front of a delivery port arranging surface of a recording head. CONSTITUTION:A distance indication member is provided with a partially fixing part 4 for loading the member on a recording head 1 and an arm part 5 having a distance indication point 6, which indicates a position which is a predetermined distance l apart from a delivery port arranging surface 7, in front of the arranging surface 7 of delivery ports 8 of the recording head 1 when the member is loaded on the recording head 1. The recording head 1 loaded with the indication member is set to an XY stage of a delivery liquid drop flying speed measuring system, liquid drops 3 are delivered from the recording head 1, and a periodic irradiation is conducted using a stroboscope or LED and a display of a flying locus is performed using a microscope, CCD camera, VTR, or the like. The time required of a delivery liquid drop 3 to fly the predetermined distance l indicated by the indicating point 6 of the indication member 6 from the delivery port 8 is read, and a delivery liquid drop flying speed is calculated from the obtained flying time and the distance l. In this manner, a correct delivery liquid drop flying distance can be always obtained, and a delivery liquid drop flying speed can be measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the speed of flying droplets ejected from an ejection port of an inkjet recording head, and an instrument used in the method.

[Prior Art] The inkjet recording method uses various types of energy such as thermal energy and mechanical energy as energy for ejecting droplets, and ejects recording liquid, such as ink, from the ejection openings of a printhead into flying droplets. Recording is performed by ejecting the liquid and adhering it to a recording material such as paper.

Characteristics of the formation of droplets ejected from an inkjet recording head include the volume of the droplets, their flight direction, and their flight speed.

It is necessary to understand these characteristics for each print head installed in a printing apparatus in order to perform more precise drive control of the print head during printing using an inkjet print head.

Among these, the flying speed of the ejected droplets is determined by the flying speed of the ejected droplets when the recording head continuously scans the recording material such as paper and performs recording. This is an important factor for setting the recording head scanning speed necessary for depositing droplets and the timing of ejecting droplets from the ejection ports of the recording head.

As shown in FIG. 6, if the flight speed of the droplet 3 ejected from the ejection port 8 of the recording head is V, and the distance from the ejection port arrangement surface 7 of the print head 1 to the recording material 2 is A, then The time T for the flying droplets discharged from the outlet to reach the recording material can be determined by T = A/v.

For example, an ejection port OR with a recording head having a plurality of ejection ports whose ejection port arrangement surface faces the recording material at 1 mm intervals.
, the flight velocity V of the droplet ejected from .

is 5 m/sec, and the flight speed V2 of the droplets ejected from the other ejection ports OR2 is 10 m/s, then the arrival time of the droplets ejected from these ejection ports to the recording material is , in the droplet from the ejection port OR+, T, = 200μ
sec, T2 = 100μ for droplets from ejection port OR2
seconds, and the time it takes for these droplets to reach the recording material is T.
A time difference of I T2 = 100 μsec will occur.

Therefore, when recording is performed by continuously moving the recording head relative to the recording material, the difference between T1 and T2 causes droplets ejected from the same recording head to land at different ejection ports. This will cause a misalignment.

For example, while scanning the recording head at a speed of 5 m/sec in a direction perpendicular to the ejection port array direction, droplets are ejected from the ejection ports at the above-mentioned flight speed, and the flying droplets are ejected from the ejection port array surface of the print head. When a dot is formed by adhering it to a recording material 1 mm away from the dot, there is a 5 μm shift in the tod formation position (impact point) in the scanning direction of the recording head between droplets with different flight speeds, as shown in Figure 7. occurs.

Therefore, variations in flight speed lead to variations in the landing points of droplets.

In order to eliminate variations in the point of impact of droplets from each ejection port on the recording material in the printhead scanning direction in such a printhead, the conditions for droplet formation at each ejection port, for example, each It is necessary to appropriately correct the driving conditions of the ejection energy generator provided corresponding to the ejection port.

In addition, when replacing the print head of a printing device with a print head that has a different droplet flying speed, the control program for driving the printing head of the printing device is adjusted to match the actual droplet flying speed of the newly installed printhead. need to be changed.

The flying speed of droplets ejected from the ejection ports of a recording head has conventionally been measured by the method described below using, for example, the measurement system shown in FIG.

First, the recording head is placed on the XY stage at a distance A from the recording material as shown in FIG.
Droplets are ejected from the ejection ports of the print head.

At a predetermined distance (Xm) from the discharge port, a strobe or LED is emitted at a delay of 100 μs,
For example, the trajectory of the ejected droplet from the ejection port is displayed as a monitor output through a microscope, COD camera, VTR, etc., and the time taken for the ejected droplet to fly a predetermined distance A and reach the recording material is displayed. The flight speed is calculated from the flight time and flight distance A obtained by reading the flight trajectory.

Note that about 20 ejections are repeatedly measured, and the average value is taken as the flight speed.

[Problems to be Solved by the Invention] In measuring the flight speed of the ejected droplet described above, in order to perform accurate measurement, it is necessary to accurately measure the flight distance A.

However, the method of determining flight distance A in the conventional method is
Measure the distance from the displayed recording head placement surface using a ruler, write the obtained distance on the display, and calculate the distance from the written placement surface to the flight distance A.
It was. In this method, ITV resolution or T
There was a problem in that accurate flight distance could not be obtained due to distortion on the V screen.

An object of the present invention is to provide a method that can always obtain an accurate flying distance of droplets when measuring the flying speed of droplets ejected from an inkjet recording head, and can measure the flying speed of droplets with high precision. There is a particular thing.

Another object of the present invention is to enable an inkjet recording head to be installed with a simple operation, and to facilitate setting of accurate flight distance of ejected droplets when measuring the flight speed of the ejected droplets of the inkjet recording head. An object of the present invention is to provide a distance indicating member having a structure.

[Means for Solving the Problems] A method for measuring the flight speed of droplets ejected from an inkjet recording head according to the present invention provides an inkjet recording head having an ejection port for ejecting flying droplets, and a method for measuring the flying speed of droplets ejected from the ejection port. A distance indicating member having an arm extending in the flight direction and having a distance indicating point indicating a position at a predetermined distance (4) from the ejection port is detachably fixed, and a droplet is ejected from the ejection port. The method is characterized in that the time t for the ejected flying droplet to reach a position at a distance 4 designated by the distance indication point is measured, and the flying speed of the ejected droplet is determined from the time t and the distance °C.

Further, the distance indicating member of the present invention that can be used in the above measurement method includes a fixing part for detachably fixing to the inkjet recording head, and a fixing part for detachably fixing to the inkjet recording head, and a distance indicating member from the ejection port of the inkjet recording head when fixed to the inkjet recording head. Extends in the flight direction of the ejected droplet and extends a predetermined distance (
l) an arm on which a distance indicating point indicating a position is arranged;
It is characterized by having the following.

By attaching the distance indicating member configured as described above to the inkjet recording head, an indicating point indicating the distance 4 that is accurately set in advance is placed in front of the ejection port arrangement surface of the print head, so that the ejection port of the print head can be easily adjusted. When measuring the flight speed of the ejected droplet from the point, the flight time of the ejected droplet is measured to the indicated point, and the flight speed of the ejected droplet is easily calculated from the obtained measurement value and distance 4. be able to. That is, there is no need to measure the exact flying distance of the ejected droplet each time as in the conventional method.

The flight time of the ejected droplets in the method of the present invention is determined by, for example, periodic irradiation using a strobe or LED using the system shown in FIG. 2 used in the conventional method described above, a microscope, and a CCD camera. Various known methods can be used, such as a method of reading from a flight trajectory displayed using a VTR or the like.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1(a) to (C) are diagrams showing the structure and usage state of the distance indicating member of the present invention, and FIG. 1(a) is a state of an example of the distance indicating member before being attached to the recording head. FIG. 1(b) is a perspective view of the distance indicating member attached to the recording head, and FIG. 1(C) is a perspective view of FIG. 1(b).
) is a side view of the state shown in FIG.

The distance indicating member shown in FIG. 1 includes a partial fixing part 4 for attachment to the recording head l, and a position in front of the arrangement surface 7 of the ejection ports 8 of the recording head 1 when attached to the recording head 1. The arm 5 has a distance indicating point 6 that indicates a position at a predetermined distance 4 from the discharge port array surface.

To attach this distance indicating member to the recording head, there is a protrusion on the left side of the recording head that serves as a reference, and by inserting the hole of the distance indicating member into the protrusion, positional accuracy is automatically achieved and the distance indicating member is attached to the recording head. This is done by being removably fixed.

The recording head equipped with the instruction member configured as described above is set, for example, on the XY stage of the ejected droplet flight speed measuring system described using FIG. 2, and droplets are ejected from the recording head. As shown schematically in Fig. 3, by periodic irradiation with a strobe or LED, and display of the flight trajectory using a microscope, CCD camera, VTR, etc. The flight time of the ejected droplet 3 up to the designated predetermined distance 4 is read, and the flight speed of the ejected droplet can be easily calculated from the obtained flight time and distance 4.

In addition, the timing of the light emission of the strobe or LED in this operation is set, for example, by sequence control of a microprocessor, to the timing at which the flight wave curve can be observed at the position where the distance indicating point of the indicating member is placed, as shown in Fig. 4. The flight time (ta,) of the ejected droplet up to a predetermined distance β can be obtained by the timing of the light emission with respect to the ejection timing of the droplet from the ejection port.

Incidentally, the process of droplets from the ejection port is schematically shown in FIG. 5. In measuring the flight speed of the ejected droplets mentioned above, the reference state is that the droplets are not ejected from the placement surface.
That is, the flight time is set to 0.

The structure of the distance indicating member in the present invention is not limited to the structure illustrated above, and can be appropriately selected as long as it can accurately arrange a point indicating a predetermined distance measurement degree in front of the ejection port array surface of the recording head. .

[Effects of the Invention] According to the method for measuring the flying speed of droplets ejected from an inkjet recording head of the present invention, there is an indication point in front of the ejection port array surface of the recording head that indicates a distance β that is accurately set in advance. This eliminates the need to measure the exact flight distance of the ejected droplet as in conventional methods, and measures the flight time of the ejected droplet to the indicated point, and then compares the obtained measured value with a preset value. The flight speed of the ejected droplet can be easily calculated from the distance β.

Moreover, the above-mentioned arrangement of the pointing points can be easily and accurately carried out by a simple operation of mounting the pointing member of the present invention, which has a simple structure, on the recording head.

[Brief explanation of drawings]

FIGS. 1(a) to (C) are diagrams showing the structure and usage state of an example of the distance indicating member of the present invention, and FIG. 2 is a block diagram schematically showing a system for measuring the flying speed of droplets discharged from the recording head. , FIG. 3 is a diagram for explaining the operation in the ejected droplet flight speed measurement method of the present invention, FIG. 4 is a diagram showing an example of droplet discharge timing and LED light emission timing in the method of the present invention, and FIG. 5 6 is a diagram for explaining the ejection process of ejected droplets from the ejection port, FIG. 6 is a diagram for explaining the conventional operation for measuring the flying speed of ejected droplets, and FIG. 7 is a diagram showing the deviation of the landing point of ink dots. FIG. 1: Recording head 2: Recording material 3; Discharged droplet 4: Fixed part 5/arm 6: Distance indication point 7: Discharge port array surface 8: Discharge port

Claims (1)

[Scope of Claims] 1) An inkjet recording head having an ejection port for ejecting flying droplets, which extends in the flight direction of droplets ejected from the ejection port and is at a predetermined distance (l) from the ejection port. A distance indicating member having an arm on which a distance indicating point for indicating a position is arranged is detachably fixed, a droplet is ejected from the ejection port, and the ejected flying droplet is set at a distance indicated by the distance indicating point. l
Measure the time (t) to reach the position, and calculate the time t and distance l
1. A method for measuring the flight speed of ejected droplets of an inkjet recording head, the method comprising determining the flight speed of ejected droplets from . 2) A fixing part for removably fixing to the inkjet recording head, and a fixing part that extends in the flight direction of droplets ejected from the ejection opening of the inkjet recording head when fixed to the inkjet recording head, and 2. The distance indicating member that can be used in the method for measuring the flying speed of droplets ejected from an inkjet recording head according to claim 1, further comprising an arm on which a distance indicating point indicating a position at a predetermined distance from the outlet is arranged.