JP6852378B2 - Device that ejects droplets - Google Patents

Description

The present invention relates to a device for ejecting droplets, and more particularly to collecting floating droplets generated by ejecting droplets.

An inkjet type image forming apparatus is known in which a droplet of a recording liquid (ink) is ejected from a recording head to form an image. Since this image forming apparatus has a structure in which droplets are ejected from a recording head, a part of the droplets may be separated during flight, or the liquid may bounce off when ink is landed on a recording medium (paper, etc.). Some of the droplets become fine droplets (hereinafter referred to as ink mist) that do not land on the recording medium (paper, etc.) and scatter inside the machine, resulting in adhesion to the inside of the image forming apparatus or gaps in the exterior. It will be released to the outside of the aircraft through.

The ink mist adhering to the inside / outside of the image forming apparatus becomes dirty, and when the user touches the hand, the hand becomes dirty, and the surrounding area where the image forming apparatus is installed becomes dirty. Further, it may adhere to optical sensors (reflection type, transmission type, encoder) inside the image forming apparatus, which may reduce the detection accuracy of each sensor and cause a malfunction.

Therefore, the ink mist generated in the image forming apparatus is collected by adhering the ink mist to a member charged at a position opposite to the injection direction of the recording head inside the apparatus by using the action of an electric field to prevent the ink mist from adhering. A technique for suppressing is already known (for example, Patent Document 1).

However, in the conventional method of creating an electric field by charging a member arranged at an opposite position on the injection side of the recording head, the mist blown up by the air flow from the inside or outside of the machine is the charged member and the ink mist. There was a problem that the ink mist could not be collected because the distance was too long.

Although the issues described above are derived from the development process of inkjet printers, even if they are regarded as a higher-level concept "device that ejects liquid", droplets like fine mist similar to ink mist , The problem of droplets that do not land on the medium remains.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable a device for ejecting droplets to collect droplets generated by the ejection of the droplets and suspended in the apparatus.

One aspect of the present invention that achieves the above object is a device for ejecting a droplet, which comprises a droplet ejection head that reciprocates in response to scanning of the droplet ejection surface in a region surrounded by an exterior. Mist recovery having electrodes arranged on the exterior above the reciprocating droplet ejection head and outside the reciprocating droplet ejection head, which is a position where airflow is generated by scanning the ejection surface. The exterior is located above the reciprocating droplet ejection head, which has a member and the airflow flows from below to above in the exterior located outside the reciprocating droplet ejection head. Then, the droplet ejection head flows in the direction of reciprocating movement, the mist collecting member includes electrodes composed of a plurality of projecting portions, and outside the reciprocating droplet ejection head, the electrodes composed of the plurality of projecting portions are provided. A plurality of electrodes extend from the lower side to the upper side, and above the droplet discharge head that reciprocates, a plurality of electrodes composed of the plurality of projecting portions extend in a direction in which the droplet discharge head reciprocates. is arranged, characterized in Rukoto.

According to the present invention, in a device that ejects droplets, it is possible to collect droplets that are generated as the droplets are ejected and float in the apparatus.

It is a block diagram which shows the schematic structure of the inkjet printer which concerns on one Embodiment of this invention. It is a block diagram which shows the schematic structure of the electrical connection of the inkjet printer of FIG. It is a figure (the 1) for demonstrating the problem (the generation of ink mist). It is a figure for demonstrating the alternating charge by the transport belt 102 of the electrostatic adsorption type. It is a figure for demonstrating the generation of ink mist by the charge of the electrostatic adsorption type transport belt 102. It is a figure for demonstrating the scanning direction of a carriage 100. It is a figure (2) for explaining a problem (generation of ink mist). It is a figure which shows the detailed structure of the carriage 100 which has a mist recovery member. It is a figure which shows the structure which arranged the mist recovery member on both side surfaces of a carriage. It is a figure which shows the structure when the mist recovery member is arranged in the upward direction. It is a figure which shows the structure which arranged the mist recovery member on the left side plate of the exterior. It is a figure which shows the structure which arranged the mist recovery member on both sides of the side plate of an exterior. It is a figure which shows the structure which the mist recovery member which the electrode of a different polarity is arranged alternately is arranged on the left side plate of the exterior, and the upper left side. It is a figure which shows the structure which arranged the mist collection member of a flat cable shape on the left side plate of the exterior, and the upper left side. It is a figure which shows the structure which the rib-shaped mist collecting member is arranged on the left side plate of the exterior, and the upper left side. It is a figure which shows the structure which arranged the cylindrical mist collection member on the left side plate of the exterior, and the upper left side of the exterior.

In the following disclosure, when collecting ink mist in a device that discharges liquid, in short, the direction of the liquid discharge head toward the nozzle surface is matched with the air flow generated in the machine by the reciprocating motion of the droplet discharge head or the carriage that supports the droplet discharge head. It is at least one of the features that a member for collecting ink mist is arranged in the carriage.

According to the above configuration, the mist collecting member arranged at a position corresponding to the generated airflow can collect the mist that has been blown up on the opposite side of the injection direction of the recording head.

Hereinafter, an "inkjet printer" will be disclosed as an embodiment of a device for ejecting a liquid, and a "recording head" will be disclosed as an embodiment of a "droplet ejection head". Further, in relation to such an embodiment, the description will proceed on the premise that ink droplets are ejected onto a flat medium such as plain paper, but the technical idea disclosed in the present application is that of a 3D printer or the like. It can also be applied to a device that ejects droplets. Prior to the disclosure of the embodiment, it should be added that the technical idea disclosed in the present application should not be construed as being applicable only to "ink droplet ejection" in an "inkjet printer". deep.

<Inkjet printer>
FIG. 1 is a schematic view showing a paper transport path of the inkjet printer 1.
The inkjet printer 1 is for stocking an apparatus main body, a paper tray 109 attached to the apparatus main body for loading paper as a recording medium, and a paper attached to the apparatus main body on which an image is recorded (formed). It is provided with a paper ejection tray 114.

As a paper feed unit for feeding paper loaded on the paper load unit (press plate) of the paper tray 109, a half-moon roller (paper feed roller 108) and a paper feed unit that separately feed paper one by one from the paper load unit. A separation pad 110 facing the roller 108 and made of a material having a large friction coefficient is provided, and the separation pad 110 is urged toward the paper feed roller 108.

Then, as a transport unit for transporting the paper fed from the paper feed unit on the lower side of the recording head 101, the paper is electrostatically attracted and conveyed to the transport belt 102 and substantially vertically upward. It includes a transport guide 112 for turning the paper by approximately 90 ° and imitating it on the transport belt 102, and a tip pressurizing roller 106 urged on the transport belt side by a pressing member. Further, it is provided with a charging roller 105 which is a charging means for charging the surface of the transport belt 102.

Here, the transport belt 102 is an endless belt, and is configured to be hung between the transport roller 103 and the tension roller 104 and circulate in the belt transport direction. The charging roller 105 is arranged so as to come into contact with the surface layer of the transport belt 102 and rotate in accordance with the rotation of the transport belt 102.

Further, as a paper ejection unit for ejecting the paper recorded by the recording head 101, a separation claw 113 for separating the paper from the transport belt 102, a paper ejection roller 107, and a paper ejection roller are provided to eject the paper. A paper ejection tray 114 is provided below the roller 107. Here, the height from between the paper ejection roller 107 and the paper ejection roller to the paper ejection tray 114 is increased to some extent in order to increase the amount that can be stocked in the paper ejection tray 114.

FIG. 2 is a diagram showing an outline of electrical connection of an inkjet printer. The inside of the dotted line shown in FIG. 2 is the function of the control board, and the outside of the dotted line shows the unit connected to the control board.

The control board is supplied with power from a power source. An operation panel for inputting and displaying information necessary for this device is connected to the control board.

The control board receives print data from the host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera by a host I / F via a cable or a net.

Then, the CPU reads out the print data in the receive buffer included in the Host I / F, analyzes it, performs image processing and data sorting processing required by the CPU, and transfers the image data to the Head control unit. .. Note that the dot pattern data for image output may be generated by storing the font data in ROM, for example, or the image data is expanded into bitmap data by the printer driver on the host side and transferred to this device. You may do so.

When the head control unit receives the image data (dot pattern data) corresponding to one line of the recording head, the head control unit transmits the dot pattern data for one line to the carriage 100 as serial data in synchronization with the clock signal. Also, a latch signal is sent to the carriage 100 at a predetermined timing.

The head drive unit is composed of a waveform generation circuit including a DAC (D / A converter) that reads pattern data of the drive waveform (head drive signal) stored in the ROM and D / A converts the drive waveform data, an amplifier, and the like. Includes a drive waveform generator.

The head mounting unit called the carriage 100 includes a shift register for inputting clock signals from the head control unit and serial data which is image data, and a latch circuit for latching the registration value of the shift register with a latch signal from the head control unit. , Including a level conversion circuit (level shifter) that changes the output value of the latch circuit and an analog switch array (switch means) whose on / off is controlled by this level shifter, etc., to control the on / off of the analog switch array. The required drive waveform included in the drive waveform is selectively applied to the actuator means of the recording head mounted in the carriage to drive the head.

Further, the CPU includes a sensor detection signal via an ADC (A / D converter) that performs A / D conversion. The main scanning, sub-scanning motor, and supply motor drive unit drives the motor by sending a drive signal to the main scanning motor and sub-scanning motor by command signals from the CPU and exciting the motor, and the movement of the motor is read by the encoder sensor. The number of rotations of the motor is controlled by feeding back the read result to the CPU. The carriage reciprocates by driving the main scanning motor.

The number of pulses of the sub-scanning encoder that is output in response to the drive of the sub-scanning motor controls the transport amount of the transport belt and outputs a control signal to the high-voltage circuit for each fixed transport amount, which is generated by the high-voltage circuit. Invert the high pressure polarity.

<Generation of ink mist>
FIG. 3 is a diagram illustrating the generation of ink mist.
The main causes of the generation of ink mist, which is a droplet floating in the device, are due to the rear end of the droplet and the rebound after landing. If a uniform electric field is present when the ink mist is generated, the charge distribution of the ink mist will be biased in one direction due to the action of electrostatic induction even if the original droplet is electrically neutral. If the transport belt side is positively charged, a negative charge is induced on the transport belt side of the droplet.

Since the ink mist separated from the droplet is a part of the droplet charged on the positive side, the ink mist is positively charged. That is, it is not electrically neutral. Therefore, the ink mist exerts a repulsive force on the positively charged transport belt and soars upward in the figure. The upper direction in the figure is the direction opposite to the discharge direction of the recording head.

FIG. 4 is a diagram for explaining alternating charging by the electrostatic adsorption type transport belt 102. As shown in FIG. 4A, the transport belt 102 rotates clockwise as the transport roller 103 rotates. By alternately applying a high-voltage square wave to the charging roller 105 at the same time as the rotation, positive and negative charges are alternately applied on the transport belt 102 (insulating layer), and an alternating electric field is formed on the transport belt 102. Then, as shown in FIG. 4B, when the paper reaches the transport belt 102 to which the alternating charge is applied, the charge in the paper is attracted to the electric field on the transport belt 102, so that an attractive force is generated.

FIG. 5 is a diagram for explaining the generation of ink mist due to the charging of the electrostatic adsorption type transport belt 102. As shown in FIG. 5, the charge of the electrostatic adsorption transport is positively charged. When an electric field is generated between the transport belt and the head, the belt side of the main droplet of ink is induced by the charging of the belt and is charged to the negative side. As a result, the side opposite to the belt of the main droplet of ink is positively charged. Therefore, the ink mist generated by the trailing edge of the droplet is positively charged.
In addition, the ink mist generated by the bounce after landing may include both a negatively charged ink mist and a positively charged ink mist. Further, the belt may be negatively charged, or the polarity may be changed periodically to charge the belt.

<Carriage operation>
Hereinafter, the configuration of the carriage 100 of the present embodiment will be described.
FIG. 6 shows a diagram for explaining the scanning direction of the carriage 100. In FIG. 6, the relative positions of the paper and the carriage 100 on the transport belt 102 as viewed from the downstream side to the upstream side in the transport direction of the transport belt 102 are shown. As shown in the figure, the carriage 100 moves in a direction orthogonal to the paper transport direction and scans back and forth. This reciprocating scanning direction may be referred to as a "main scanning direction".

FIG. 7 is a diagram for explaining an air flow generated by scanning the carriage 100. Since the carriage 100 operates as shown in FIG. 6, there is a possibility that the ink mist moves as shown in FIG. 7 in the conventional device.

When the carriage moves in the outward direction, the air that was in the position where the carriage moved due to the slipstream principle moves to the original position of the carriage. Therefore, the airflow generated by the movement of the carriage is the airflow that flows from the front of the carriage (movement direction) to the back of the carriage (opposite the movement direction).

When the carriage moves in the return direction, the air that was in the position where the carriage moved due to the slipstream principle moves to the original position of the carriage. Therefore, the airflow generated by the movement of the carriage is the airflow that flows from the front of the carriage (movement direction) to the back of the carriage (opposite the movement direction).

The present embodiment includes the configuration described below in order to collect the ink mist as shown in FIG. 7. FIG. 8 is a diagram showing a detailed configuration of a carriage 100 having an ink mist collecting member.

In FIG. 8, the mist collecting member 115 is arranged on the opposite side of the carriage 100 in the moving direction. Further, a voltage is applied to the mist recovery member 115. By applying this voltage, the mist recovery member 115 is charged, and when the ink mist charged in the opposite polarity of the mist recovery member 115 passes in the immediate vicinity of the mist recovery member 115 by the air flow, the ink mist is recovered by the electric field.

As described in FIG. 7, since the airflow generated by the carriage scanning flows from the front to the rear side of the carriage 100, the mist collecting member 115 is attached to the rear side of the carriage 100 and the ink mist is collected by charging the high pressure. Can be done.

The mist collecting members 115 shown in FIG. 8 are preferably provided on both sides of the carriage 100 in the scanning direction. FIG. 9 is a diagram for explaining a case where the mist collecting member 115 is arranged on both side surfaces of the carriage.

In FIG. 8, the ink mist collecting member is arranged only on the opposite side in the outward direction. However, in that case, the ink mist cannot be collected because the ink mist does not approach the ink mist collecting member 115 when moving in the return direction during bidirectional printing. Therefore, by arranging the mist collecting member 115 on both side surfaces of the carriage 100 and charging the carriage 100, the ink mist can be collected even when moving in the outward direction and the return direction. Further, according to this example, the recovery rate of ink mist can be improved.

Next, a configuration will be described in which the mist collecting member is provided further above the space through which the airflow flows as the carriage 100 moves (the “upper” here is the opposite side of the ink ejection surface direction). FIG. 10 is a diagram showing a configuration when the mist collecting member 116 is arranged in the upward direction.

As described in FIG. 7, by scanning the carriage 100, the air around the carriage 100 passes under and above the carriage 100 and escapes from the front to the rear. Therefore, the mist collecting member 116 is arranged on the upper side of the carriage 100, which is the passage of the air flow, and the ink mist is collected by the mist collecting member 116 by charging the mist collecting member 116. According to this example, the recovery rate of ink mist can be improved.

Next, in addition to the configurations of FIGS. 8 to 10, the mist collected in the exterior portion is collected before the airflow including the ink mist generated by scanning the carriage 100 flows into the space before the movement of the carriage 100. The configuration of collecting by the member 117 will be described with reference to FIGS. 11 and 12.

FIG. 11 is a diagram showing a configuration in which the mist collecting member 117 is arranged on the left side plate of the exterior. In the example of FIG. 11, the mist collecting member 117 is arranged on the left side plate of the exterior exterior of the scanning region. When the carriage 100 has completely moved in the outward direction, air passes between the carriage 100 and the side plate of the exterior to generate an air flow. Therefore, by arranging the mist collecting member 117 on the side plate of the exterior and charging the ink mist, the ink mist can be collected by the mist collecting member 117. Although it is installed on the exterior in this configuration, it does not have to be the exterior as long as it is a side plate on the outside of the scanning area.

FIG. 12 is a diagram showing a configuration in which the mist collecting member 117 is arranged on both sides of the side plate of the exterior. In the example of FIG. 12, the mist collecting member 117 is arranged on both sides of the side plate of the outer exterior of the scanning region. When the carriage 100 has completely moved in the outward direction, air passes between the carriage 100 and the side plate of the exterior to generate an air flow. Therefore, by arranging the mist collecting member 117 on the side plate of the exterior and charging the ink mist, the ink mist is collected by the mist collecting member 117. At the same time, when the carriage 100 has completely moved in the return direction, air passes between the carriage 100 and the side plate of the exterior to generate an air flow. Therefore, by arranging the mist collecting member 117 on the side plate of the exterior and charging the ink mist, the ink mist is collected by the mist collecting member 117. According to this configuration, the recovery rate of ink mist can be further improved. Although it is installed on the exterior in this configuration, it does not have to be the exterior as long as it is a side plate on the outside of the scanning area.

<Other Embodiments>
Next, as another embodiment, a case where the mist recovery member 118 is composed of electrodes that alternately repeat different polarities will be described.

FIG. 13 is a diagram showing a configuration in which the mist collecting member 118 is arranged on the left side plate and the upper left side of the exterior, and the arrangement configuration of the mist collecting member 118 is similar to the combination of FIGS. 10 and 11. It has become. The mist recovery member 117 of FIG. 13 has a configuration in which electrodes of different polarities are alternately repeated at narrow intervals, and the recovery efficiency is improved by increasing the electric field generated when a voltage is applied. Further, by providing an electrode that alternately repeats different polarities, it is possible to improve the recovery efficiency of ink mist charged in each of the positive and negative directions by the transport belt 102.

Next, FIG. 14 is a diagram showing a configuration in which the flat cable-shaped mist collecting member 118 is arranged on the left side surface and the upper left side of the exterior. In FIG. 14, a plurality of cables arranged side by side are configured to alternately repeat different polarities. An aggregate of cables is called a flat cable shape. The "flat cable shape" here does not limit a specific material, of course, to the flat cable itself, and has the same function as the mist collecting member 118 of FIG. 13, and the member itself is thin. It would be good if the conversion could be realized. Further, it is preferable that the structure is such that it can be adhered to the exterior. As described above, by forming the mist collecting member 118 into a flat cable shape, there is an advantage that space saving of the member can be realized and the degree of freedom of arrangement is increased. The different polarities may be alternately repeated for each cable, or may be alternately repeated for each of a plurality of cables.

Next, FIG. 15 is a diagram showing a configuration in which the rib-shaped mist collecting member 118 is arranged on the left side surface and the upper left side of the exterior. The "rib shape" here is not limited to a specific material. For example, the surfaces of the carriage 100 facing in the moving direction have a plurality of irregularities, and the protruding portions are configured to alternately repeat different polarities. The mist collecting member 118 composed of the plurality of irregularities has the same function as the mist collecting member 118 of FIG. By forming the mist recovery member 118 in a rib shape in this way, the recovery area is increased as compared with the case where the surfaces facing the moving direction of the carriage 100 are horizontal (for example, the side area of the uneven portion is also the recovery area). Therefore, improvement in ink mist collection efficiency can be expected. The different polarities may be alternately repeated for each protrusion, or may be alternately repeated for each of a plurality of protrusions.

Next, FIG. 16 is a diagram showing a configuration in which the cylindrical mist collecting member 118 is arranged on the left side surface and the upper left side of the exterior. The "cylindrical shape" here does not limit a specific material, and for example, a positively charged cylindrical mist collecting member 118 and a negatively charged cylindrical mist collecting member 118 are defined. The mist collecting member 118 having a plurality of cylindrical shapes, which is configured to be repeated alternately at intervals, has the same function as the mist collecting member 118 of FIG. By forming the mist collecting member 118 into a cylindrical shape, the mist collecting member 118 itself has an effect of making it difficult to obstruct the air flow generated by the carriage scanning. Further, in contrast to the mist collecting member 118 of FIG. 14, it is preferable to arrange the members at a certain distance from the exterior. By arranging in this way, the range of the surface area for collecting the ink mist can be expanded, and the efficiency of collecting the ink mist can be expected to be improved. In this description, it has been described as "cylindrical shape", but the same applies to the case where it has a cylindrical shape instead of a cylindrical shape. Further, although the different polarities are alternately repeated for each mist collecting member in FIG. 14, they may be alternately repeated for each of a plurality of mist collecting members.

As described above, since the mist recovery member 118 is composed of electrodes that alternately repeat different polarities, it can be expected that the ink mist recovery efficiency, the space saving of the member, and the cost reduction of the member can be expected. The arrangement of the mist collecting member 118 is not limited to the above and FIGS. 13 to 16. For example, it may be arranged not only on the left side plate of the exterior which is the outward direction of the carriage scanning, but also on the right side plate of the exterior which is the return direction, and further on the upper right side of the exterior.

100 Carriage 101 Head 115 Mist recovery member 116 Mist recovery member 117 Mist recovery member 118 Mist recovery member

Japanese Unexamined Patent Publication No. 2013-060023

Claims (1)

A device that ejects droplets with a droplet ejection head that moves back and forth in response to scanning of the droplet ejection surface in the area surrounded by the exterior.
A mist having electrodes arranged on the exterior above the reciprocating droplet ejection head and the outer exterior of the reciprocating droplet ejection head, which is a position where an air flow is generated by scanning the ejection surface. Has a recovery member
The airflow flows from below to above in the exterior located outside the reciprocating droplet ejection head, and the droplet ejection in the exterior located above the reciprocating droplet ejection head. The head flows in the direction of reciprocating movement,
The mist collecting member includes electrodes composed of a plurality of protrusions, and on the outside of the reciprocating droplet ejection head, a plurality of electrodes composed of the plurality of protrusions extend from the lower side to the upper side and are arranged. above the liquid droplet discharge head for the reciprocating movement, the electrode consisting of the plurality of projections and wherein the Rukoto a plurality arranged to extend in a direction in which the liquid droplet ejection head reciprocates, discharge droplets Equipment to do.

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