JPH06340078A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To provide a means for greatly reducing a disorder in a recording image due to a change in relative positions between a rotary drum and a recording head caused by various factors in an ink jet recording device which performs recording by ejecting liquid ink from a delivery nozzle. CONSTITUTION:A laser doppler speed sensor (LDV) 15 for sensing the speed of the surface of a recording medium 9 on a rotary drum 8 is provided on a moving base 2 of a recording head 1 to control the delivery of ink droplets based on the output signal of the sensor 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting ink droplets to record on a recording medium.

[0002]

2. Description of the Related Art An example of a conventional general ink jet recording apparatus will be described with reference to the schematic diagram of FIG. 4; 1 is a recording head for ejecting ink to perform recording, and 2 is a recording head supporting / moving the recording head 1. The moving table 3 for supporting the moving table 2
A pair of guide rails for guiding, 4 is a motor for driving the moving base 2, 5 is a pulley directly connected to the motor 4, 6 is a driven pulley arranged to face the pulley 5,
7 is a wire wound around the pulley 5 and the driven pulley 6 to transmit the power of the motor 4 to the moving base 3, 8 is a rotary drum for supporting / rotating a recording medium 9 such as recording paper, 10
Is a drum motor for rotating the rotating drum 8, 11
Is a rotary encoder for detecting the rotation angle of the rotary drum 8 and outputting a predetermined signal, and 12 is the recording head 1.
Is a cap for protecting the discharge nozzle from drying during standby, 13 is an arrow indicating the moving direction of the moving table 2, 14
Is an arrow indicating the rotation direction of the rotary drum 8. Also,
Reference numeral 16 is a processing circuit for processing the electric signal from the encoder 11, and 17 is a control circuit for controlling the ejection of the recording head 1.

When this apparatus performs recording, the recording head 1 whose nozzles are protected by the cap 12 separates from the cap 12 and the power from the motor 4 is wound around the pulley 5 and the driven pulley 6 by the wire 7. And is moved to the recording medium 9 together with the moving table 2.

Further, the rotating drum 8 is rotated in the direction of arrow 14 by the drum motor 10 together with the recording medium 9, the encoder 11 generates a predetermined electric output accordingly, and the processing circuit 16 performs a predetermined processing on the output. Control circuit 1
Reference numeral 7 generates an ejection signal based on the electric signal, and the recording head 1 ejects ink droplets to a predetermined position in accordance with the ejection signal.
When the recording head 1 finishes recording for one line, it moves to the recording position of the next line together with the movable table 2 to record the line,
Further, predetermined recording is performed by repeating these steps.

[0005]

However, the conventional example as described above has the following problems.
That is, although the encoder 11 is provided in consideration of the accuracy of the position of the ink droplet hitting the surface of the recording medium 8 of the recording head 1 in the rotation direction of the rotary drum 8, FIG.
In the conventional example shown in FIG. 3, ink droplets are ejected from the recording head 1 according to a signal from the encoder 11. However, the target detected by the encoder 11 is only the angle or the angular velocity of the rotary drum 8, and the surface of the recording medium 9 is detected. Or the relative speed between the rotary drum 8 and the recording head 1. For this reason, the desired ink ejection position may be different, and as a result, the recorded image may be disturbed.

The causes thereof include deformation and eccentricity of the outer peripheral shape of the rotary drum 8 in the direction of the rotation center axis, a change in diameter due to temperature change, a change in thickness of the recording medium 9, and the like. Further, due to insufficient rigidity of the guide rail 3 or the like, the same result may be brought about when the relative position of the rotary drum 8 and the recording head 1 changes periodically.

The present invention has been made in view of the problems of the conventional example as described above, and an object thereof is to provide a means for significantly reducing the above-mentioned disorder of a recorded image.

[0008]

Therefore, in the present invention, in an ink jet recording apparatus of the type that ejects liquid ink from an ejection nozzle to perform recording, at least one recording head that ejects ink droplets, and this recording head. A moving table for supporting and reciprocating the recording medium, a rotating drum for supporting and rotating the recording medium, and a detecting means for non-contact detecting the moving speed of the surface of the recording medium on the rotating drum. The detection means is mounted on the movable table in the vicinity of the recording head, outputs an electric signal, and discharges ink droplets from the recording head in accordance with the electric signal.

[0009]

With the relatively simple structure as described above, it is possible to perform recording with very little image distortion.

[0010]

EXAMPLES The present invention will be described below with reference to a plurality of examples: (Example 1) FIG. 1 is a schematic view of a first example of an ink jet recording apparatus of this type according to the present invention. Conventional example The same (corresponding) constituent elements as in FIG. 4 are represented by the same reference numerals. Reference numeral 1 is a recording head for ejecting ink droplets to perform recording, 2 is a moving base for supporting / moving the recording head 1, 3 is a pair of guide rails for supporting / guidering the moving base 2, 4 is a motor for driving the moving base 2, 5 is a pulley directly connected to the motor 4, 6 is a driven pulley arranged so as to face the pulley 5, 7 is a pulley 5 and a driven pulley 6
A wire wound around the wire for transmitting the power of the motor 4 to the moving table 2, 8 is a rotary drum for supporting / rotating a recording medium 9 such as recording paper, and 10 is a drum for rotationally driving the rotary drum 8. The motor 12 is a cap for protecting the ejection nozzles from drying etc. while the recording head 1 is on standby,
Reference numeral 13 is an arrow indicating the moving direction of the moving base 2, and 14 is an arrow indicating the rotating direction of the rotary drum 8.

Reference numeral 15 denotes a laser Doppler type speed sensor (hereinafter abbreviated as LDV) according to the present invention for detecting the speed of an object to be measured in a non-contact manner, which is mounted near the recording head 1 of the movable table 2. The recording medium 9 is arranged at a position where the surface speed of the recording medium 9 can be detected. Reference numeral 16 is a processing circuit for applying a predetermined processing such as frequency division to the output from the LDV 15, 17
Is a control circuit for controlling the ejection of the recording head 1 according to the electric signal.

When this apparatus performs recording, the recording head 1 whose nozzles are protected by the cap 12 is separated from the cap 12 and the power from the motor 4 is wound around the pulley 5 and the driven pulley 6 by the wire 7. Transmitted by
It moves onto the recording medium 9 together with the moving table 2 and the LDV 15.

On the other hand, the rotary drum 8 rotates in the direction of arrow 14 by the power of the drum motor 10 together with the recording medium 9,
The LDV 15 detects the surface speed of the recording medium 9 and outputs its electric signal. Since a frequency signal proportional to the speed is obtained from the LDV 15, the frequency signal can be divided by the processing circuit 16 and used as the ejection signal from the control circuit 17. The recording head 1 ejects ink droplets in accordance with this ejection signal, but since the LDV 15 is mounted on the moving table 2 in the vicinity of the recording head 1, the recording at the time when the recording head 1 always tries to perform positive recording. The relative speed between the medium 9 and the recording head 1 can be detected. As a result, the rotary drum 8 is not affected by various factors such as deformation, eccentricity, diameter change due to temperature change, and the like, which exist in the conventional example.
Since ink droplets can be ejected at a desired accurate position on the recording medium 9, it is possible to record with extremely little image distortion.

(Embodiment 2) FIG. 2 shows a schematic diagram of a second embodiment according to the present invention. The same (corresponding) constituent elements as those of the first embodiment shown in FIG. The description is omitted. This example uses 4 to obtain a full color image.
It is a recording apparatus of a case provided with a recording head of a book. 1a,
Recording heads 1b, 1c, and 1d respectively eject yellow, magenta, cyan, and black ink droplets, and are arranged at substantially equal intervals. Reference numeral 15 is an LDV capable of detecting the speed of the object to be measured in a non-contact manner, and is mounted on the moving table 2 near the middle position of the four recording heads 1a to 1d.

The reason why there are only four LDVs 15 instead of four of these recording heads is as follows. That is, the recording heads 1a to
When the so-called bubble jet method is used for 1d, the thickness is as thin as about 10 mm, so the distance between them is about 15 mm, and the total of four recording heads can be as small as about 45 mm. Is the recording head 1a-
This is because the speed variation during the passage over 1d is relatively small.

By dividing the electric signal output from the LDV 15 and shifting the ink ejection timing by a time corresponding to each recording head interval, ink droplets can be ejected to a desired accurate position on the recording medium 9. Becomes Other configurations and operations are the same as those in the first embodiment, and therefore, duplicated description will be omitted.

(Embodiment 3) FIG. 3 shows a schematic diagram of a third embodiment according to the present invention. The description of the same (corresponding) constituent elements as in the first embodiment is based on the case of the second embodiment. In this embodiment, the arrangement position of the LDV 15 for detecting the surface speed of the recording medium 9 is on the upstream side in the moving direction of the recording medium 9 with respect to the recording head 1 and almost in the moving direction of the moving table 2. It is placed on the movable table 2 at the same position.

By configuring as in this embodiment,
Since the LDV 15 does not come out of the recording medium 9 before the recording head 1, it does not hinder the image recording even near the recording end. Other configurations and operations are the same as those in the first embodiment, and therefore redundant description will be omitted.

The present invention further includes means for generating thermal energy as energy used for ejecting ink, particularly in an ink jet recording apparatus,
In the recording head and recording apparatus of the type in which the thermal energy causes a change in the state of the ink, an excellent effect is brought about. According to this method, the recording density is increased,
This is because high precision can be achieved.

With regard to its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous types, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the flow path. By applying at least one drive signal corresponding to the recorded information and causing a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. As a result, bubbles can be formed in the liquid (ink) corresponding to the drive signal, which is effective. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, U.S. Pat. Nos. 4,463,359 and 4,345 are used.
Those as described in the '262 patent are suitable. If the conditions described in US Pat. No. 4,313,244 of the invention relating to the rate of temperature rise of the heat acting surface are adopted, further excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. The configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose the configuration in which the heat acting portion is arranged in the bending region, are also effective in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration corresponding to the ejection portion.

Further, although the serial type ink jet recording apparatus is shown in the embodiment, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum recordable width. As a full-line type recording head, by a combination of a plurality of recording heads as disclosed in the above-mentioned specification, either a configuration that satisfies the length or a configuration as one recording head integrally formed is used. Although good, the present invention can more effectively exhibit the above-mentioned effects.

Further, it is preferable to add recovery means for the recording head and preliminary auxiliary means provided as a constitution of the ink jet recording apparatus of the present invention because the effects of the present invention can be further stabilized. Specific examples thereof include capping means, cleaning means, pressurization or suction means, an electrothermal converter or a heating element other than this, a preheating means for the recording head, and a recording head for the recording head. It is also effective to perform a stable recording by performing a preliminary discharge mode in which another discharge is performed.

Regarding the type and number of recording heads and inks to be mounted, for example, single color ink and 1
In addition to one provided with a plurality of recording heads, a plurality of heads may be provided corresponding to a plurality of inks having different recording colors and densities, and any combination is effective. The present invention is effective not only as a recording mode of black or the like as a recording mode of the recording apparatus but also in a full-color recording mode of different colors or mixed colors.

In the above-described embodiments of the present invention, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and softens or melts at room temperature, or the above-mentioned ink. In the inkjet, it is common to control the temperature of the ink itself in the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is in a stable ejection range. Anything can be used. In addition, in order to prevent temperature rise due to heat energy, ink that is positively used as energy for phase change from solid state to liquid state, or ink that solidifies when left standing for the purpose of preventing ink evaporation is used. In any case, the thermal energy such as the one that the ink is liquefied by the application of the thermal energy according to the recording signal and ejected as an ink liquid, or the one that has already started to solidify when it reaches the recording medium is used. The use of an ink having the property of liquefying for the first time is also applicable to the present invention. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Further, the present invention is an ink jet system such as a piezo jet system in which electricity is converted into a force to eject ink, and a recording system in which a recording head is disposed in non-contact with a recording medium and ink is ejected for recording. Is effective in.

In addition, as a form of the recording apparatus of the present invention, a copying apparatus which is integrally or separately provided as an output terminal of information processing equipment such as the word processor and the computer as described above, or a copying apparatus which is combined with a scanner or the like, Further, it may be in the form of a facsimile machine having a transmission / reception function.

[0028]

As described above, according to the present invention,
On the moving base of the recording head, a speed detecting means for the surface of the recording medium on the rotating drum is provided, and since the ink droplets are ejected based on the output signal thereof, the rotating drum is deformed, eccentric,
Even if problems such as increase or decrease in diameter due to temperature change occur, the ink ejection position on the recording medium is not affected,
As a result, there is an effect that it is possible to always obtain recording with extremely little image distortion.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a first embodiment.

FIG. 2 is a schematic diagram of a second embodiment.

FIG. 3 is a schematic diagram of a third embodiment.

FIG. 4 is a schematic diagram of an example of a conventional inkjet recording device.

[Explanation of Codes] 1 recording head 2 moving table 8 rotating drum 9 recording medium 15 laser Doppler type velocity sensor (LDV) 16 processing circuit 17 control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Asuwa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. In an inkjet recording apparatus of a type that ejects liquid ink from an ejection nozzle to perform recording, at least one recording head that ejects ink droplets, and a moving table that supports and reciprocates the recording head. The recording medium is provided with a rotating drum for supporting and rotating a recording medium, and a detecting means for detecting the moving speed of the surface of the recording medium on the rotating drum in a non-contact manner. An ink jet recording apparatus, which is mounted near a head, outputs an electric signal, and ejects ink droplets from the recording head according to the electric signal. 2. The recording head is provided for each of a plurality of ejecting sections for ejecting ink and corresponding ejecting sections, and causes the ink to undergo a state change due to heat, and ejects the ink from the ejecting section based on the state change. The inkjet recording apparatus according to claim 1, further comprising: a thermal energy generating unit that discharges the droplets to form flying droplets.