JPH05254121A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To dissolve a problem, in a pneumo-electric control type ink jet recorder, that the distance between adjacent heads is varied depending on the fixing accuracy of head and the dots are superposed while being shifted. CONSTITUTION:A pressure detection part 11 is provided to a fixed platen 1 oppositely to a scan locus of air discharge opening 12-15 of respective heads 6-9, each of which measures an interval between pulses outputted from the pressure detection part 11 by an air flow when the air discharge openings 12-15 are opposed respectively to the pressure detection part 11 by counting a pulse outputted from a linear scale reader part 4 as an accurate distance between the heads. Those values are stored in a CPU or the like and superposition of dots is accurately performed by adjusting discharge timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static electricity control type ink jet recording apparatus for ejecting ink toward a recording medium together with an air flow discharged from an air outlet.
In particular, when a plurality of heads are attached along the scanning direction, it is characterized by means for measuring the distance between the adjacent heads.

[0002]

2. Description of the Related Art In recent years, an ink jet recording apparatus which is low in noise and low in price has been attracting attention as an output apparatus for OA equipment.

A static control type ink jet recording apparatus which is one type of conventional ink jet recording apparatus will be described below.

FIG. 3 is a sectional view of a static control type ink jet head. In FIG. 3, reference numeral 21 is an ink nozzle plate made of a glass material, and an ink discharge port 20 is formed in the ink nozzle plate by an etching method or the like. Reference numeral 19 denotes an air nozzle plate made of a glass plate, on which an air ejection port 17 through which ink is ejected together with an air flow is formed by an etching method or the like. Reference numeral 23 is a space through which air passes, and air 3
0 enters through the air inlet 28, and constantly flows out through the air outlet 24 through the air chamber 24 and the void 23.
Reference numeral 26 denotes a ceramic or resin body, which fixes the ink nozzle plate 21 and the air nozzle plate 19, and forms the ink chamber 25 and the air chamber 24. The ink 31 enters through the ink inlet 27. 22 is the ink discharge port 2
It is a signal electrode for applying a potential to the ink formed around 0, and a pulsed voltage is applied by the signal source 29.

Reference numeral 18 denotes a common electrode, which is an air nozzle plate 19
Is formed on the top surface by a vacuum deposition method or the like. The principle of ink ejection is that the same air pressure is applied to the ink chamber 25 and the air chamber 24, and the ink is supplied to the tip of the ink ejection port 20. The air passes through the narrow space 23 and constantly exits from the air outlet 17. At this time, the air in the void 23 receives a slight pressure loss, so that the pressure on the ink chamber 25 side becomes slightly high, and as a result, the ink is discharged from the ink ejection port 2
A convex meniscus is formed at the tip of 0. When a potential difference is applied between the signal electrode 22 and the common electrode 18 in this state, the force causes the ink to be ejected in the form of threads, and the ink is stably ejected from the air ejection port 17 toward the recording medium by riding on the air flow. One dot is recorded for the pulse voltage.

A printing operation of a static control type ink jet recording apparatus having a plurality of such ink jet heads will be described.

As shown in FIG. 4, four ink jet heads 6 to 9 having the above-described structure are fixed to the carriage 5 along the scanning direction, and the carriage 5 is provided in parallel with the fixed platen 1. The main scanning rail 16 is moved from left to right or right to left to print one line on the recording medium 3. The printing point is the main scanning rail 16
It is determined by counting the pulses output from an encoder that is composed of a linear scale 10 that extends in parallel with and is provided with graduations at equal intervals, and a reading unit 4 that sequentially reads the graduations. After printing one line, the paper feed roller 2 feeds the recording medium 3 for one line, and printing of the next line is continued.

The ink jet heads 6 to 9 are filled with black, cyan, magenta, and yellow inks, respectively, and color printing is performed by four heads.

Now, assuming that printing is performed while the carriage 5 moves from left to right, in the case where dots are recorded by the same nozzle of each head at any ejection position and the dots are overlapped with each other, it is determined between the predetermined heads. It is necessary to delay the ejection timing by a delay amount corresponding to the interval of 4 and to superimpose 4 colors in the order of yellow, magenta, cyan, and black.

[0010]

However, since the distance between the heads is not constant due to an error in mounting the heads and the delay amount is different from the design value, the superposition is not successful. Therefore, the actual printing is performed after the assembly. However, there is a problem in that the amount of delay between heads must be corrected according to the printing result, and it takes a long time for adjustment.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an ink jet recording apparatus having means capable of automatically detecting the delay amount between heads.

[0012]

In order to achieve this object, an ink jet recording apparatus of the present invention has a head group in which a plurality of ink jet heads are integrally arranged along the scanning direction, and the air ejection of each head is performed. A detecting means for detecting the pressure of the air flow flowing out from the outlet is provided so as to face the scanning locus of the head group, and the distance between the adjacent inkjet heads is measured from the interval of the detection output of the detecting means. .

[0013]

According to the above construction, the distance between the adjacent heads can be determined by detecting the pressure of the air flow flowing out from the air discharge port of each head each time each ink jet head passes the front surface of the detecting means in the scanning state. Since the measurement can be easily performed, the delay amount of the print data can be optimized and the misalignment of the dot superposition can be prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In the present embodiment, as shown in FIG. 1, a portion of the surface of the fixed platen 1 which is not covered with the recording medium 3 and which is provided in the ink jet heads 6 to 9 has air ejection ports 12 to. A pressure detection unit 11 is provided at a position opposed to the scanning locus of 15 and the air discharge ports 12 to 15 pass on the pressure detection unit 11 when the carriage 5 moves. .

The operation of the ink jet recording apparatus configured as described above will be described with reference to FIG.
Now, assuming that the carriage 5 is moving from the left to the right, the air ejection port 15 of the head 9 is first detected by the pressure detection unit 1.
1, the signal A is output from the pressure detection unit 11 at this time. Next, the air discharge ports 14, 13, 12 are located on the pressure detection unit 11 in this order, and the signal B from the pressure detection unit 11
The signals C and D are output in this order.

When the carriage 5 moves, the reading means 4 of the linear scale 10 outputs a signal E which is a position signal. The signal A to signal D rises or falls. The distance between adjacent nozzles can be measured by counting the number of E pulses by a CPU or the like.

In this case, the distance between the signal A and the signal B is the head delay amount between the ink jet head 9 and the ink jet head 8, and the distance between the signal B and the signal C is between the ink jet head 8 and the ink jet head 7. The head-to-head delay amount, and the distance between the signals C and D is the head-to-head delay amount between the inkjet head 7 and the inkjet head 6. Therefore, if each of the count values is stored and the ejection delay amount between the heads is controlled by the count value, the four colors can be accurately superimposed.

That is, the above-described operation makes it possible to accurately measure the head-to-head delay amount. By storing this value in the CPU or the like and adjusting the ejection timing, it becomes possible to accurately superimpose dots. This embodiment has one head
Although the case where the nozzle is provided is shown, it is obvious that the present invention can be applied to the case where a plurality of nozzles are provided.

[0020]

As described above, according to the present invention, the distance between the nozzles of the adjacent heads can be automatically measured by detecting the pressure of the air flow flowing out from the air discharge port of each head, so that the delay amount of print data can be measured. Can be easily optimized and deviation of dot superposition can be prevented.

[Brief description of drawings]

FIG. 1 is a front view showing a main part of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the pressure detection unit.

FIG. 3 is a cross-sectional view of a main part of a head portion of a static control inkjet recording apparatus.

FIG. 4 is a perspective view showing a main part of a conventional static control inkjet recording device.

[Explanation of symbols]

 1 Fixed Platen 2 Paper Feed Roller 3 Recording Medium 4 Linear Scale Reading Unit 5 Carriage 6 to 9 Inkjet Head 10 Linear Scale 11 Pressure Detection Unit 12 to 15 Air Discharge Port

Claims (1)

[Claims] 1. An ink ejection port, one of which is in communication with an ink chamber, is arranged so as to face each other with a predetermined gap in the air ejection port, and air is continuously discharged from the air ejection port through the gap. In this state, by intermittently applying a predetermined pulse voltage between the air discharge port and electrodes provided around the ink discharge port, the ink from the ink discharge port is discharged from the air discharge port together with the air flow. In an ink jet recording apparatus having a head group in which a plurality of ink jet heads for intermittently ejecting and printing on the recording medium are integrally arranged along a scanning direction, an air flow flowing out from an air ejection port of each head A detecting means for detecting the pressure is provided so as to face the scanning locus of the head group, and the distance between the adjacent inkjet heads is determined from the interval of the detection output of the detecting means. Distance jet recording apparatus characterized by measuring the.