JPH02179772A - Image recorder - Google Patents

Abstract

PURPOSE:To obtain a high-quality image free from a blur in line drawing, color deviation, and color irregularities by a construction wherein a movable belt guide member is mounted inside a carry belt for feeding recording paper, and the recording paper is abutted against a recording head containing member through an abutting member provided on the guide member. CONSTITUTION:On the side opposed to recording heads 1C, 1M, 1Y, and 1Bk, a belt guide member (platen) 115 is installed through a carry belt 101. A pin 116 is provided on the platen 115 on the surface abutting on the carry belt. The recording heads 1C, 1M, 1Y, and 1Bk are respectively abutted against a head abutting surface 6H of a head block 6. The outside of the head abutting surface 6H is a pin abutting surface 6P to be abutted with the pin 116. The parallelism of the head abutting surface 6H and the pin abutting surface 6P is held to have an accuracy as high as a difference in recording by each recording head can be substantially prevented from occurring because a gap between recording paper and the recording heads is required to be kept.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an image recording device having functions such as a facsimile machine, a copying machine, and a printer, and a multifunctional device having such functions;
The present invention relates to an image recording device used as an output device for a workstation or the like.

[Conventional technology]

Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among them, there is a possibility of high-speed recording,
Moreover, the inkjet recording method is an extremely powerful recording method that can perform recording on so-called plain paper without requiring any specific fixing process.

A recording head applied to an inkjet recording device generally includes a fine liquid ejection opening (orifice), a liquid path, an energy acting part provided in a part of this liquid path, and a droplet forming device that acts on the liquid in the acting part. It is equipped with an energy generation means for generating energy.

Energy generating means for generating such energy include recording methods using electromechanical transducers such as piezo elements, irradiating electromagnetic waves such as lasers, absorbing them into the liquid and generating heat, and generating heat due to the zero heat generation. Discharges droplets by action,
There are recording methods that use energy generating means to make the liquid fly, or recording methods that use energy generating means that ejects the liquid by heating the liquid with an electrothermal converter such as a heating element having a heating resistor. Among these, the recording head used in the inkjet recording method, which discharges liquid using thermal energy, has a high density array of liquid discharge ports (orifices) for discharging recording droplets to form flying droplets. This makes it possible to record with high resolution. Among these, a recording head that uses an electrothermal converter as a thermal energy generating means is easy to make the overall size of the recording head compact, and is based on IC technology and microelectromechanical technology, which have recently made significant advances in technology and reliability in the semiconductor field. It is possible to fully utilize the advantages of processing technology, and it is easy to make it long and planar (two-dimensional), so it is easy to make multi-nozzles and high-density packaging, and it is also highly productive in large quantities. It is also possible to provide an inkjet recording head that is inexpensive to manufacture and an apparatus having the head.

In this way, using an electrothermal converter as an energy generation means,
An inkjet recording head manufactured through a semiconductor manufacturing process generally has a liquid path corresponding to each orifice, and applies thermal energy to the liquid filling the liquid path for each liquid path to draw the liquid from the corresponding orifice. An electrothermal transducer is provided as a means for ejecting liquid to form flying droplets. In addition, liquid is supplied to these liquid paths from a common liquid chamber communicating with each branch path.

FIG. 5 is a schematic configuration diagram of such an inkjet recording head, in which an electrothermal converter 1103, an electrode 1104, and a liquid are formed on a substrate 1102 through semiconductor manufacturing process steps such as etching, vapor deposition, and sputtering. Road wall 1
105 and a top plate 1106, an inkjet recording head is shown. The recording liquid 1112 is supplied into the common liquid chamber 1108 of the recording head 1101 from a liquid storage chamber (not shown) through a liquid supply pipe 1107. In the figure, 1109 is a liquid supply pipe connector. The liquid 1112 supplied into the common liquid chamber 1108 is supplied into the liquid path 1110 by a so-called capillary phenomenon, and is stably held by forming a meniscus at the discharge port surface (orifice surface) at the tip of the liquid path. By supplying electricity to the electrothermal converter 1103, the liquid on the surface of the electrothermal converter is rapidly heated, bubbles are generated in the liquid path, and the expansion and contraction of the bubbles causes the liquid to be discharged from the discharge port 1111. A droplet is formed. With the above-described configuration, a high-density ejection port arrangement such as an ejection port density of 16 nozzles/mm, 128 ejection ports or 256 ejection ports, or even a multi-nozzle inkjet in which ejection ports are arranged over the entire recording width can be achieved. A recording head can be formed.

FIG. 6 is a schematic perspective view showing a configuration example of an inkjet printing apparatus in which the above-described inkjet printing head is actually arranged in the printing apparatus. In the figure, a print head 1101 similar to the above-described print head is driven by a motor 12.
The carriage 1214 is configured integrally with the carriage 1214 which is reciprocated on the rail 1213a by the drive of the carriage 1213a. Ink tank 1222Y, 1222M.

The ink contained in 1222C and 1222B is supplied into the recording head 1101 by pumps 1223Y, 1223M, 1223C and 1223B. The recording member (recording paper) is conveyed along the platen roller 1212 and temporarily stopped. Then, the recording head 1101 is connected to the rail 121.
While moving forward along lines 3a and 1213b, ink is ejected to record an image. After recording an image for a predetermined paper width, the recording head 1101 moves to the rail 1213a again.

It moves back along 1213b and returns to the home position, but
During this time, the recording paper is moved to the desired length by the platen roller 1212.
It is transported and stopped again. Then, image recording is performed by repeating such operations.

A recording method in which printing is performed while reciprocating the recording head on the stopped recording paper is hereinafter referred to as a serial scan method.

[Problem to be solved by the invention]

In such an inkjet recording device, when small droplets of ink are ejected from the nozzle and deposited on the recording paper,
Ink droplets may be ejected in a distorted manner due to the characteristics of each nozzle or the adhesion of ink near the nozzle. Therefore, it is necessary to maintain the distance between the nozzle surfaces of the plurality of heads and the recording paper at a constant value of about 0.5 mm over the entire surface of the recording paper. If this distance is not kept constant, the ink droplets will deviate from the point they should reach on the recording paper, causing color misalignment or color unevenness, or in the case of line drawings, straight lines may become distorted.

Conventionally, the recording head section 305 and the belt conveyance section 304
It was difficult to keep this distance constant because the distance between the two was determined individually. In particular, it has been difficult to maintain the positioning accuracy of the recording head section 305, which moves between the standby position and the printing position every time a printing operation is performed.

[Objective and means]

The present invention aims to solve the above-mentioned problems, and in order to maintain a constant distance between the nozzle surface of the recording head and the printing surface of the recording paper, a movable belt guide member is installed inside the conveyor belt that conveys the recording paper. is provided, and the recording head is brought into contact with the storage member through an abutment member provided on the guide member.

〔Example〕

FIG. 1 is a schematic sectional view showing essential parts of the present invention.

The details of the printing sequence will be explained with reference to this figure and FIG. 3 which explains the movement of the printing section.

First, the ink supply to the full-line elongated recording head used in this embodiment will be explained with reference to FIG. FIG. 7 is an explanatory diagram schematically showing the configuration of the elongated recording head and ink supply means, in which 1601 is the recording head, 1652 is a common liquid chamber in the recording head 1601, and 1653 is a recording liquid ejection surface. 1654 is a discharge port for discharging liquid. However, the discharge 0165 of this embodiment
Numerals 3 and 3 selectively drive heat-generating elements provided in liquid paths (not shown) leading to the individual ejection ports 1653, whose numbers are arranged all over the recordable width of the target recording material. This makes it possible to eject the recording liquid and perform recording without moving or scanning the head itself.

1655 is a recording liquid supply tank for supplying recording liquid to the recording head 1601; 1656 is a main tank for replenishing the supply tank 1655 with recording liquid;
55 to the recording head 16 through a supply pipe 1657.
When replenishing the recording liquid, the recording liquid can be refilled from the main tank 1656 to the supply tank 1655 by a recovery pump 1659 via a one-way replenishment rectifier valve 1658. Also, 16
60 is a one-way recovery rectifier valve used during a recovery operation to recover the ejection function of the recording head 1601;
1661 is a circulation pipe in which a recovery rectifier valve 1660 is interposed, and 1662 is the above-mentioned first supply pipe 16.
A solenoid valve 57 is installed, and 1663 is an air vent valve for the supply tank.

In the recording head 1601 and its recording supply system and recovery system configured in this way, when recording is performed, the solenoid valve 16
62 is kept in an open state, and recording liquid is supplied from the supply tank 1655 to the common liquid chamber 1652 by its own weight, and from the liquid chamber 1652 to the discharge port 165 via a liquid path (not shown).
I am guided by 3. In addition, during a recovery operation performed to remove air bubbles remaining in the common liquid chamber 1652 and the supply system and to cool the recording head 1601, the recovery pump 1659 is driven to supply the recording liquid to the common liquid chamber 16 through the circulation pipe 1661.
52 and from the common liquid chamber 1652 to the first supply pipe 16
57 allows the recording liquid to be returned to the supply tank 1655 for circulation. Furthermore, at the time of initial filling of the liquid path, etc., with the solenoid valve 1662 closed, the pump 1659 pumps the recording liquid through the circulation pipe 1661 to the common liquid chamber 1652, and as the bubbles are discharged, the recording liquid is discharged from the discharge port 1653. can be done.

Normally, such a recording head is left with ink remaining inside the ink ejection openings when not recording. A capping means having a cap that can be joined to the ejection port surface or the ejection port side of the print head is provided, and the cap and the print head are bonded during non-printing, so that the print head can be covered with a cap and the surroundings can be covered. The evaporation of the ink liquid in the liquid path and its attendant effects are avoided by sealing the air space at the joint part with ink vapor and bringing the space formed by the cap and the recording head to the saturated vapor pressure of the ink. Prevents increase in viscosity and drying of ink in the liquid path. However, in low-humidity environments or when recording is stopped for a long period of time, the viscosity of the ink may increase even if the above-mentioned capping is performed to prevent the ink liquid in the liquid path from evaporating. During printing after the printing pause period, it may not be possible to prevent ink from being ejected from the ejection ports or from being ejected unstablely. In the present invention, the problem of whether or not ink is ejected for the first time after a pause is solved as follows.
called "problem". To solve this problem, as described above, the recovery pump 1659 is driven to circulate and pressurize the ink, and an ink circulation and pressure means is also used to discharge the ink from all the ejection ports of the recording head. There is. Furthermore, if the above-mentioned non-ejection condition is slight, the entire energy generating means of the head is driven to perform an ink ejection operation similar to that used for recording on paper or the like. Since this is not ejection for recording an image, it is hereinafter referred to as "dry ejection" in the present invention.

As mentioned above, if the ink dries up due to being left in a non-recording state for a long time and its viscosity increases and it becomes stuck in the ejection port and/or the liquid path, pressurized circulation of the ink will cause the non-recording state to occur again. If the stuck state is slight in a relatively short period of time, the head is rotated to a state where printing can be performed by an idle ejection operation.

FIG. 7 shows a schematic configuration diagram of an image forming apparatus using the above-mentioned multi-orifice elongated recording head.

In FIG. 7, reference numeral 301 is a scanner part that converts image information into an electrical signal according to the image information of a document, and a signal based on the converted electrical signal is given to a recording head unit 305 of a printer part 302 as a drive signal. Paper feed section 3
Recording paper is stored in 03, and is sent out one by one toward the belt conveyance section 304 when necessary. At this time, the recording head unit 305 is at a standby position 305' indicated by a broken line (
It is located at the recording position indicated by the solid line. When the recording paper passes through the gap D between the belt conveying section 304 and the recording head section 305, the recording head IC, I based on the image information
M, IY.

An image is recorded on the recording paper by receiving ink ejected from the IBk. Thereafter, the sheet is sent out onto the tray 420 via the fixing sheet discharge section 307. Note that 306 is a recovery cap section, which has a function of allowing the recording head section 305 to maintain a stable recording state at all times.

In an apparatus with this configuration, since the recording head section covers the paper width, it is possible to obtain an image recording over the entire surface of the recording paper simply by passing under the recording head section 305. High-speed printing is possible compared to other methods. Further, since the recording head unit 305 does not need to perform scanning movement during recording, even more stable image formation can be achieved.

Figure 1 shows the registration rollers (belt conveyance unit) of the recording member (recording paper) conveyance means (Figure 1 415°41
6), the recording paper reaches the conveyor belt 101 along the guide plates 417 and 418. The conveyor belt 101 has an insulating layer (preferably a volume resistance of 10'2 Ω·Cm or less) on the side where the recording paper is placed, and a conductive layer (volume resistance 108 Ω·Cm or less) on the opposite side.
It is desirable to set it to Cm or less. ) has a two-layer structure. This conveyor belt 101 is wound around a driving roller 102, a driven roller 103, and a tension roller 10-4°105, and is attached with a tension of, for example, 2 to 5 kg. The conveyor belt 101 is moved in the direction of arrow AA in the figure by a motor (not shown) that is connected to a drive roller 102 and applies a driving force to the drive roller 102 .

The recording paper is placed on the conveyor belt 101 immediately in front of the conductive roller 107. At this time, the surface of the conveyor belt 101 is given a potential of several hundred to several thousand volts by the charger 106. When the recording paper placed on the conveyor belt 101 reaches the grounded conductive roller 107, the recording paper and the conveyor belt 10
Since the recording paper is kept in close contact with the conveyor belt 101 by electrostatic adsorption force, the recording paper is closely attached to the conveyor belt 101 and moves together with the conveyor belt 101.

In this state, the recording paper reaches the recording area facing the recording head section 305.

108, head block 6, recording head IC, IM;

IY, IBk, and the recording heads IC, IM, IY
.

A belt guide member (hereinafter referred to as a platen) 115 is provided on the side facing IBk via the conveyor belt 101. Further, the platen 115 is provided with a pin 116,
Spring 117. platen 115 by guide pin 118
is pressed and supported on the recording head section 305 side. Therefore, the platen 115 pushes up the conveyor belt 101 toward the head block 6 by the force of the spring 117. At this time, the conveyor belt 101 and the recording heads IC, IM,
In order to keep the distance to IY and lBk within a predetermined range, the flatness of the surface platen 115 in contact with the conveyor belt is determined by several tens of degrees.
It is desirable that the thickness be about μm or less. A pin 116 is provided on the side of the platen 115 that contacts the conveyor belt.

As shown in FIG. 2, two pins 1.16 are provided at the front and rear of the platen 115. On the other hand, the recording heads IC, IM, IY, and IBk are each abutted against the head abutment surface 6H of the head block 6. The outside of the head contact surface 6H is a pin contact surface 6P against which the pin 116 comes into contact, and the parallelism between the head contact surface 6H and the pin contact surface 6P is to maintain the distance between the recording paper and the recording head. , the precision is maintained to such an extent that recording differences between the respective recording heads are virtually impossible (for example, on the order of several tens of μm).

Here, the operation of the recording head section 305 will be explained using FIG. 3. When a copy start command is issued, the recording head unit 305 moves from the standby position to the print position. first(
a) The cap is in standby or hibernation mode. By selecting the print mode (copy on) in this state, the above-described idle ejection operation is first performed. Subsequently, the state shown in FIG. 3(b) head-up is reached, that is, the state in which the head is retracted upward.

In this state, the recovery system container 2 is retracted toward the upper right. This state is (C) unit oven, and after this state, (d) head down is performed.

As a result, as shown in FIG. 3(d), the head is placed in a printable state, and the recovery system container is placed in the retracted position.

When the recording head section 305 moves to the state shown in FIG. 3(d), it becomes the state shown in FIG. 1. At this time, head block 6
The pin abutment surface 6P touches the upper surface of the pin 116, and acts as if to push down the platen l1.5.

When the platen 115 is pushed down to the printing state shown in FIG. , IBk
A gap l can be formed with high precision between the conveyor belt 101 and the conveyor belt 101.

In this case, for example, even if the head abutment surface 6H or pin abutment surface 6P of the head block 6 is tilted in the front and back, if the repulsive force of the spring 117 is appropriately selected so that the four pins 116 touch each other, the inclination can be adjusted. Since the platen 115 follows the same pattern, the value of 2 is maintained accurately.

Furthermore, if the pin 116 is screwed in or otherwise replaceable, the value of l can be easily changed.

In this state, the recording paper moves through the gap l in the direction of arrow A in the figure, and is printed by each print head. Since the recording paper is brought into close contact with the belt 101 due to electrostatic attraction, and the belt 101 is moved in close contact with the platen 105, the distance between the recording surface of the recording paper and the head can be formed with high accuracy. After printing is completed, the recording paper is sent to the next fixing section and then ejected from the machine. Further, the conveyor belt 101 has an ink absorber 119
Cleaning is performed as necessary by a cleaner 120 equipped with a cleaner.

On the other hand, the print head section after printing is shown in FIG. 3(e).

After passing through the state of (f), it returns to the standby position (FIG. 3(a)).

Furthermore, it is often difficult to form an abutment surface on the head block 6 with high precision. In that case, another positioning means may be provided against which the print head and the pin abut. Other positioning means include print heads IC, LM, and IY.

FIG. 4 shows a case where positioning shafts 130 are provided at both ends of IBk. The positioning shaft 130 is supported by the head block 6 (not shown). The print heads IC, IM are aligned with the upper part of this positioning shaft 130 as a reference.

IY and IBk are fixed by, for example, biasing means (not shown). platen 115 and print heads IC, LM, and IY.

The distance from platen 1 to IBk is the same as in the previous embodiment.
It is set by the pin 116 on the head printing unit 305 side hitting the member on the head printing unit 305 side, but in this example, it is set by hitting the lower part of the positioning shaft 130. In general, the straightness and outer diameter tolerance of the shaft can be manufactured with an accuracy of several tens of micrometers, so in this case, the print head IC, LM,
The distance between IY, IBk and the platen 115 can also be determined accurately, and as a result, the distance between the recording surface of the recording paper and the head can be maintained with high accuracy. Alternatively, the pin 116 may be made into a single member with the platen 115 instead of being made into a separate member.
For example, the platen 115 may be formed of a sheet metal, and the function corresponding to the pin 116 may be provided by bending or drawing.

〔effect〕

As described above, the conveying means guide member that guides the conveying means that conveys the recording paper is movable, and the conveying means guiding member and the member that positions the plurality of recording heads are positioned via the abutting member. By doing so, it is possible to accurately maintain the distance between the nozzle surface of the recording head and the recording surface of the recording paper, and it is possible to obtain high-quality images without line drawing irregularities, color shifts or color unevenness in the case of color images. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the main parts of the image recording apparatus according to the present invention, FIG. 2 is a schematic top view of the main parts of FIG. 1, and FIG. FIG. 4 is a schematic perspective view showing another embodiment of the image recording apparatus of the present invention, and FIG. 5 is an inkjet recording head applicable to the present invention. 6 is a schematic configuration diagram of an ink jet recording apparatus in which the recording head in FIG. 5 is arranged; FIG. 7 is a configuration diagram of a long recording head and ink supply means applicable to the present invention; This figure is a schematic sectional view of an image forming apparatus using four elongated recording heads shown in FIG. 7. 101... Conveyor belt 115... Belt guide member (platen) 116...
Pin 6...Head block IC-lBk...Print head diagram (method) % formula % 2. Name of the invention Image recording device 3. Relationship with the person making the amendment

Claims (5)

[Claims] (1) A conveyance means for conveying recording paper, a plurality of recording heads, a storage container for storing the plurality of recording heads, and a conveyance means guide member arranged so as to place the conveyance means between the recording heads. and an abutting member provided between the storage container and the conveyance means guide member, wherein the conveyance means guide member is movable. (2) The image recording apparatus according to claim 1, wherein there are four abutment members. (3) A conveyance means for conveying recording paper, a plurality of recording heads, a storage container for storing the plurality of recording heads, and a conveyance means guide member arranged so as to place the conveyance means between the recording heads. An image recording device comprising: a means for positioning a plurality of recording heads; and an abutting member provided between the positioning means and a conveyance means guide member, wherein the conveyance means guide member is movable. Device. (4) The image recording apparatus according to claim 3, wherein the positioning means is provided near both ends of the recording head. (5) The image forming apparatus according to any one of claims 1 to 4, wherein the abutment member is integrated with the conveying means guide member or is a single member.