JP4602786B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a liquid discharge head.

  As various image forming apparatuses such as printers, facsimiles, copying machines, plotters, printer / fax / copier multifunction machines, etc., a recording head composed of a liquid discharging head that discharges recording liquid (for example, ink) droplets is mounted on the carriage. Thus, this carriage is referred to as a recording medium (hereinafter also referred to as “paper”, but the material is not limited to paper, and is also referred to as recording medium, recording paper, transfer material, etc.). Are scanned in the orthogonal direction, and the recording medium is transported intermittently according to the recording width, and an image is formed on the recording medium by repeating conveyance and recording alternately (recording, printing, printing, printing) Is also used synonymously.) There are serial type and line type.

In an image forming apparatus equipped with such a liquid discharge head, the liquid discharge head normally discharges several pl to several tens of pl of ink droplets from a small-diameter nozzle having a diameter of about several tens of μm to form an image on a sheet. Form. In this case, the ink that is the recording liquid is supplied from the ink cartridge to the head. However, if the nozzles become clogged due to dust or foreign matter entering the head, droplet ejection failure occurs, so an ink supply path for supplying ink to the head A filter is provided in a part of the ink to filter the ink.
JP 2003-237108 A JP 2002-210960 A JP 2002-361893 A

  By the way, in the liquid discharge head in which the filter is integrated like the heads described in the above-mentioned Patent Documents 1 and 2, there is no possibility of foreign matter mixing from the outside because there is no attachment or detachment of components on the downstream side of the filter. Depending on the material, the filter cannot be directly fixed to the head, and the filter is often provided separately from the liquid discharge head as described in Patent Document 3.

  As described above, when the liquid discharge head and the unitized filter are separately provided, it is necessary to connect a plurality of components via the seal member (sealing member) downstream from the filter.

Therefore, for example, in Patent Document 3, the connecting portion is formed into a tube shape and sealed with an O-ring, and in Patent Document 4, similarly, sealing is performed in the radial direction using a packing member. It is described that a packing member in a form that covers up to the end of a partial flow path forming tube is used.
JP-A-5-201016 Japanese Patent Laid-Open No. 2002-19123 JP 2002-178541 A

  However, although the seal structure using the O-ring of Patent Document 1 is simple, when dust is generated by rubbing with the O-ring or a fitting member when the O-ring is frictionally inserted, dust is generated in the ink flow path. There is a problem of being mixed.

  Similarly, even in the seal structure that seals in the radial direction using the packing member of Patent Document 2, when dust is generated due to rubbing when the packing member is attached to the flow path forming member, There is a problem that garbage will be mixed.

  Furthermore, in the sealing structure using the packing member of Patent Document 3, since the packing member covers the end of the flow path forming tube, dust when the packing member is inserted into the flow path forming tube is ink. Although not mixed in the flow path, in order to seal in the surface direction, it is necessary to uniformly deform the packing member by an external force in order to securely seal the ink, and in the radial direction due to elastic deformation of the packing member itself. There is a problem that it is difficult to obtain a highly reliable sealing performance as compared with a sealing structure.

  The present invention has been made in view of the above problems, and can form an image that can easily seal the connecting portion between the liquid ejection head and another member while suppressing the entry of dust into the recording liquid supply path. An object is to provide an apparatus.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
In an image forming apparatus in which a liquid discharge head having a nozzle for discharging a recording liquid droplet is connected to a filter unit including a filter for filtering the recording liquid supplied to the liquid discharge head.
A tubular connection part is provided on at least one of the liquid discharge head and the filter unit, and a connection part fitted on the outer peripheral side of the tubular connection part on the other side;
Between the one tubular connecting portion and the other connecting portion is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and a direction different from the radial direction, and these two connecting portions A sealed space is formed between the sealing parts ,
A rib is formed on a sealing member constituting a sealing portion in a direction different from the radial direction or on a connecting portion facing the sealing member .

An image forming apparatus according to the present invention includes:
A liquid discharge head having a nozzle for discharging recording liquid droplets is connected to a member separate from the liquid discharge head and downstream of the filter means for filtering the recording liquid supplied to the liquid discharge head. In the image forming apparatus,
A tubular connecting part is fitted to at least one of the members downstream from the liquid discharge head and the filter means, and the other has a connecting part fitted to the outer peripheral side of the tubular connecting part;
Between the one tubular connecting portion and the other connecting portion is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and a direction different from the radial direction, and these two connecting portions A sealed space is formed between the sealing parts,
The rib is formed in the sealing member which comprises the sealing part of the direction different from the said radial direction, or the connection part side which opposes this sealing member
The configuration.

An image forming apparatus according to the present invention includes:
In an image forming apparatus in which a liquid discharge head having a nozzle for discharging a recording liquid droplet is connected to a filter unit including a filter for filtering a recording liquid supplied to the liquid discharge head.
A tubular first connecting portion on one of the liquid discharge head and the filter unit, and a second connecting portion fitted on the outer peripheral side of the first connecting portion on the other;
A sealing member for sealing between the first connecting portion and the second connecting portion;
The sealing member includes a first sealing portion that seals a gap between the first connecting portion and the second connecting portion in a radial direction, a tip surface of the first connecting portion, and the second connecting portion. A second sealing portion that seals the gap in the plane direction,
The sealing member includes a first packing member having an O-ring-shaped first sealing portion formed at a front end portion, and a plate-like second sealing portion that is continuous with a rear end of the first packing member. And a second packing member forming
A sealed space is formed between the first sealing portion and the second sealing portion of the sealing member.
The configuration.
An image forming apparatus according to the present invention includes:
A liquid discharge head having a nozzle for discharging recording liquid droplets is connected to a member separate from the liquid discharge head and downstream of the filter means for filtering the recording liquid supplied to the liquid discharge head. In the image forming apparatus,
A tubular first connecting portion on one of the members downstream of the liquid discharge head and the filter means, and a second connecting portion fitted on the outer peripheral side of the first connecting portion on the other;
A sealing member for sealing between the first connecting portion and the second connecting portion;
The sealing member includes a first sealing portion that seals a gap between the first connecting portion and the second connecting portion in a radial direction, a tip surface of the first connecting portion, and the second connecting portion. A second sealing portion that seals the gap in the plane direction,
The sealing member includes a first packing member having an O-ring-shaped first sealing portion formed at a front end portion, and a plate-like second sealing portion that is continuous with a rear end of the first packing member. And a second packing member forming
A sealed space is formed between the first sealing portion and the second sealing portion of the sealing member.
The configuration.

According to the image forming apparatus of the present invention, the tubular connecting portion is fitted into at least one of the liquid discharge head and the filter unit or the member downstream of the filter means, and the other is fitted into the outer peripheral side of the tubular connecting portion. And the space between one tubular connecting portion and the other connecting portion is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and in a direction different from the radial direction. Since a sealed space is formed between the two sealing parts, and the rib is formed on the sealing member constituting the sealing part in the direction different from the radial direction or the connecting part side facing this sealing member , Both the recording liquid seal and the dust seal can be performed, and the connecting portion can be easily sealed while suppressing the entry of dust into the recording liquid supply path.
According to the image forming apparatus of the present invention, the tubular first connecting portion is fitted to one of the liquid discharge head, the filter unit, or the member downstream of the filter means, and the other is fitted to the outer peripheral side of the first connecting portion. And a sealing member that seals between the first connecting part and the second connecting part, and the sealing member is provided between the first connecting part and the second connecting part in the radial direction. A first sealing portion to be sealed, and a second sealing portion for sealing the space between the front end surface of the first connecting portion and the second connecting portion in a surface direction, and the sealing member is provided at the front end portion The first packing member in which the O-ring-shaped first sealing portion is formed and the second packing member that forms the plate-like second sealing portion continuously with the rear end of the first packing member are integrally formed. In addition, since the sealed space is formed between the first sealing portion and the second sealing portion of the sealing member, both the recording liquid seal and the dust seal can be performed. Come, it is possible to perform sealing of the coupling portion easily while suppressing the contamination of dust into the recording liquid supply path.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 2 is an explanatory plan view of the mechanism portion.

  In this image forming apparatus, a carriage 4 is slidably held in a main scanning direction by a guide rod 2 and a stay 3 which are guide members horizontally mounted on left and right side plates 1A and 1B constituting a frame 1, and a main scanning motor. 5 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG. 2 via the timing belt 7 spanned between the driving pulley 6A and the driven pulley 6B.

  The carriage 4 includes, for example, a recording head 11 composed of four droplet ejection heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The nozzle rows on the nozzle surface 11a on which the ejection ports (nozzles) are formed are arranged in a direction (sub-scanning direction) orthogonal to the main scanning direction, and the ink ejection direction is directed downward. Although an independent droplet discharge head is used here, a configuration in which one or a plurality of heads having a plurality of nozzle rows that discharge droplets of recording liquid of each color can be used. Further, the number of colors and the arrangement order are not limited to this.

  As an inkjet head constituting the recording head 11, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. It is possible to use a shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet.

  A driver IC is mounted on the recording head 11 and connected to a control unit (not shown) via a harness (flexible print cable) 12.

  In addition, the carriage 4 is equipped with a sub tank 15 for each color for supplying ink of each color to the recording head 11. Each color sub-tank 15 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 9 via the ink supply tube 16 of each color. The cartridge loading section 9 is provided with a supply pump unit 17 for feeding the ink in the ink cartridge 10, and the ink supply tube 16 is attached to the rear plate 1C constituting the frame 1 in the middle of turning. It is held by the locking member 18.

  On the other hand, as a paper feed unit for feeding the paper 22 stacked on the paper stacking unit (pressure plate) 21 of the paper feed tray 20, a half-moon roller (feed) that separates and feeds the paper 22 one by one from the paper stacking unit 21. A separation pad 24 made of a material having a large friction coefficient is provided opposite to the sheet roller 23 and the sheet feeding roller 23, and the separation pad 24 is biased toward the sheet feeding roller 23 side.

  In order to feed the paper 22 fed from the paper feeding unit to the lower side of the recording head 11, a guide member 25 for guiding the paper 22, a counter roller 26, a conveyance guide member 27, and a tip pressure roller. And a holding belt 28 as a conveying means for electrostatically attracting the fed paper 22 and conveying it at a position facing the recording head 11.

  The conveyance belt 31 is an endless belt, is configured to wrap around the conveyance roller 32 and the tension roller 33 and circulate in the belt conveyance direction (sub-scanning direction). 34 is charged (charged).

  The transport belt 31 may be a single-layer belt or a multi-layer (two or more layers) belt. In the case of the conveyance belt 31 having a one-layer structure, the entire layer is formed of an insulating material because it contacts the paper 32 and the charging row 34. In the case of the transport belt 31 having a multi-layer structure, the side that contacts the paper 22 and the charging roller 34 is preferably formed of an insulating layer, and the side that does not contact the paper 22 and the charging roller 34 is preferably formed of a conductive layer. .

As an insulating material for forming the transport belt 31 having a single-layer structure or an insulating material for forming the insulating layer of the transport belt 31 having a multi-layer structure, for example, a conductive material such as PET, PEI, PVDF, PC, ETFE, or PTFE is used. is preferably a material that does not contain a control material, a volume resistivity ^{10 12} [Omega] cm or higher, preferably formed so that 101 ⁵ [Omega] cm. Further, as a material for forming the conductive layer of the transport belt 31 having a multi-layer structure, it is preferable that carbon is contained in the resin or elastomer so that the volume resistivity is 10 ⁵ to 10 ⁷ Ωcm.

The charging roller 34 is disposed so as to come into contact with an insulating layer (in the case of a multilayer belt) that forms the surface layer of the transport belt 31 and to rotate following the rotation of the transport belt 31. It is over. The charging roller 34 is formed of a conductive member having a volume resistivity of 10 ⁶ to 10 ⁹ Ω / □. As will be described later, for example, a 2 kV positive / negative AC bias (high voltage) is applied to the charging roller 34 from an AC bias supply unit (high voltage power supply). The AC bias may be a sine wave or a triangular wave, but a square wave is more preferable.

  In addition, a guide member 35 is disposed on the back side of the conveyance belt 31 so as to correspond to a printing area by the recording head 11. The guide member 35 has an upper surface that protrudes toward the recording head 11 from the tangent line of the two rollers (the conveyance roller 32 and the tension roller 33) that support the conveyance belt 31, thereby maintaining high-precision flatness of the conveyance belt 31. Like to do.

  The transport belt 31 rotates in the belt transport direction of FIG. 2 when the transport roller 32 is rotationally driven by the sub-scanning motor 36 via the drive belt 37 and the timing roller 38. Although not shown, an encoder wheel having a slit is attached to the shaft of the conveying roller 32, and a transmission type photosensor for detecting the slit of the encoder wheel is provided, and the wheel encoder is configured by the encoder wheel and the photosensor. It is composed.

  Further, as a paper discharge unit for discharging the paper 22 recorded by the recording head 11 to the paper discharge tray 40, a separation claw 41 for separating the paper 22 from the transport belt 31, a paper discharge roller 42, and paper discharge The roller 43 is provided.

  A duplex unit 51 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 51 takes in the paper 22 returned by the reverse rotation of the transport belt 31, reverses it, and feeds it again between the counter roller 26 and the transport belt 31. The upper surface of the duplex unit 51 is a manual feed tray 52.

  Further, a maintenance / recovery mechanism 61 for maintaining and recovering the state of the nozzles of the recording head 11 is disposed in a non-printing area on one side in the scanning direction of the carriage 4. The maintenance / recovery mechanism 61 includes cap members (hereinafter referred to as “caps”) 62 a to 62 d (hereinafter referred to as “caps 62” when not distinguished) and nozzles for capping the nozzle surfaces 11 a of the recording head 11. A wiper blade 63 that is a blade member for wiping the surface 11a, an empty discharge receiver 64 that receives liquid droplets when performing an empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and the like It has. Here, the cap 62a is a suction and moisture retention cap, and the other caps 62b to 62d are moisture retention caps.

  Further, in the non-printing area on the other side of the scanning direction of the carriage 4, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 68 is disposed, and the idle discharge receiver 68 is provided with an opening 69 along the nozzle row direction of the recording head 11.

  Further, an encoder scale 72 having slits is provided on the front side of the carriage 4 along the main scanning direction, and an encoder sensor 73 including a transmission type photosensor for detecting the slits of the encoder scale 72 is provided on the front side of the carriage 4. These components constitute a linear encoder 74 for detecting the position of the carriage 4 in the main scanning direction.

  In the image forming apparatus configured as described above, the paper 22 is separated and fed one by one from the paper feeding unit, and the paper 22 fed substantially vertically upward is guided by the guide 25, and the conveyance belt 31 and the counter roller 26. The leading end is guided by the conveying guide 27 and pressed against the conveying belt 31 by the leading end pressure roller 29, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately and repeatedly applied to the charging roller 34 from an AC bias supply unit, which will be described later, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 31 alternates, that is, a loop In the sub-scanning direction, which is the direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 32 is fed onto the conveying belt 31 that is alternately charged with plus and minus, the paper 22 is attracted to the conveying belt 31 by electrostatic force, and the paper 22 is conveyed in the sub-scanning direction by the circular movement of the conveying belt 31. Is done.

  Therefore, by driving the recording head 11 according to the image signal while moving the carriage 4, ink droplets are ejected onto the stopped paper 22 to record one line, and after the paper 22 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 22 has reached the recording area, the recording operation is finished and the paper 22 is discharged onto the paper discharge tray 40.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 32 is fed into the double-sided paper feeding unit 51 by rotating the conveyor belt 31 in reverse. The paper 22 is reversed (with the back surface being the printing surface), fed again between the counter roller 26 and the conveyor belt 31, controlled in timing, and conveyed by the conveyor bell 31 as described above. After recording on the back surface, the paper is discharged onto the paper discharge tray 40.

Next, a first embodiment of a connection structure of a filter unit and a liquid discharge head provided between a liquid discharge head and a sub tank constituting a recording head in the image forming apparatus will be described with reference to FIG.
Here, a liquid discharge head 101 that discharges droplets and a filter unit 102 that includes a filter that filters the recording liquid supplied to the liquid discharge head 101 are separately configured, and the liquid discharge head 101 and the filter unit are separated. The head unit 100 is configured by connecting to the head 102.

  First, the liquid discharge head 101 includes a flow path plate 201 formed of, for example, a single crystal silicon substrate, a vibration plate 202 bonded to the lower surface of the flow path plate 201, and a nozzle plate 203 bonded to the upper surface of the flow path plate 201. And a pressure liquid chamber 206 through which a nozzle 204 that ejects ink droplets communicates via a communication path 205, a fluid resistance portion 207, and a communication portion 209 that communicates with the liquid chamber 6 via a fluid resistance portion 207. The recording liquid (for example, ink) is supplied from the common liquid chamber 208 formed in the frame member 217 described later to the communication portion 209 through the supply port 210 formed in the vibration plate 202.

  An upper end portion of the multilayer piezoelectric element 212 as a pressure generating unit corresponding to each pressurized liquid chamber 206 is provided on the outer side of the diaphragm 202 that forms the wall surface of the liquid chamber 206 (on the side opposite to the liquid chamber 206). The lower end portion of the multilayer piezoelectric element 212 is bonded and fixed to the support substrate 213.

  The piezoelectric element 212 is formed by alternately stacking piezoelectric material layers and internal electrodes. In this case, the ink in the liquid chamber 206 may be pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 212, or the pressurized liquid chamber 206 using the displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 212. It can also be configured to pressurize the inner ink.

  Further, the periphery of the vibration plate 202 is adhesively bonded to a frame member 217 made of, for example, an epoxy resin or polyphenylene sulfite, or formed of metal or the like. Etc. are fixed to each other. The frame member 217 is formed with the common liquid chamber 208 described above and a supply path (communication pipe) 218 for supplying the recording liquid from the outside to the common liquid chamber 208.

  The portion of the frame member 217 in which the supply path 218 is formed is a tubular connecting portion 219 whose outer peripheral shape is tubular in order to connect with the filter unit 102.

  Further, an FPC cable 220 is connected to the piezoelectric element 12 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. The FPC cable 220 is selectively connected to each piezoelectric element 212. A drive circuit (driver IC) (not shown) for applying a drive waveform is mounted.

  Here, the flow path plate 201 is formed by anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110), for example, using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so A through hole serving as the pressure fluid chamber 206, a groove serving as the fluid resistance portion 207, and a through hole serving as the communication portion 209 are formed.

  The diaphragm 201 is formed from a nickel metal plate, and is manufactured by an electroforming method. In the diaphragm 202, a portion corresponding to the pressurized liquid chamber 206 is a thin portion for facilitating deformation.

  In the liquid ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the plurality of piezoelectric elements 212 according to an image recorded from a control unit (not shown). By applying the voltage, the piezoelectric element 212 to which the pulse voltage is applied is displaced to deform the vibration plate 202 in the direction of the nozzle plate 203 and pressurize the liquid in the liquid chamber 206 by changing the volume (volume) of the liquid chamber 206. Thus, droplets are ejected from the nozzles 204 of the nozzle plate 203.

  As the liquid droplets are discharged, the pressure in the liquid chamber 206 decreases, and a slight negative pressure is generated in the liquid chamber 206 due to the inertia of the liquid flow at this time. Under this state, by turning off the voltage application to the piezoelectric element 212, the diaphragm 202 returns to the original position, and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. At this time, the recording liquid that has entered the common liquid chamber 208 from the sub tank or the like via the filter unit 102 is filled into the liquid chamber 206, and droplets are ejected from the nozzle 204 in response to the next drive pulse application.

  Next, the filter unit 102 incorporates a filter 222 for filtering the recording liquid in the case 221, and the case 221 is provided with a connecting portion 223 that is connected to the connecting portion 219 of the frame member 217 of the liquid discharge head 101 and a sub tank. The connection part 224 for connecting with is provided. The connecting portion 223 is also a tubular connecting portion, and an opening 225 corresponding to the supply path 218 of the frame member 217 is formed in the bottom 221a provided on the base side of the connecting portion 223.

  Note that the frame member 217 of the liquid ejection head 100 is formed of resin, and if a thermoplastic resin is used, the filter can be directly fixed to the frame member 217. Here, however, the frame member is a thermosetting resin or metal. When it is difficult to directly fix the filter with ceramics, glass or the like, or in order to increase the filter area, the filter unit and the liquid discharge head are separated.

Next, a connection structure between the liquid discharge head 101 and the filter unit 102 will be described.
A first packing member 231 that is a sealing member (seal member) that seals the connecting portion 223 of the filter unit 102 and the connecting portion 219 of the frame 217 of the liquid discharge head 101 in a radial direction, and a direction different from the radial direction. The first packing member 231 and the second packing are connected by connecting through a second packing member 232 that is a sealing member (seal member) to be sealed (here, referred to as a surface direction). A sealed space 233 is formed between the member 232 and the member 232.

  Here, the first packing member 231 is, for example, an O-ring, and the connecting portion 219 of the frame 217 whose outer peripheral surface is cylindrical (tubular) and the connecting portion of the filter unit 102 whose inner peripheral surface is cylindrical (tubular). By interposing between 223, between the connecting part 219 and the connecting part 223 in the radial direction is sealed (sealed).

  The second packing member 232 seals between the front end surface of the connecting portion 219 of the frame member 217 and the bottom portion 221 a of the case 221 of the filter unit 102. The second packing member 232 has a function of preventing dust generated when the first packing member 231 is fitted into the outer peripheral surface of the connecting portion 219 of the frame member 217 from entering the supply path 218. is doing.

  That is, when the first packing member 231 is fitted into the outer peripheral surface of the connecting portion 219 of the frame member 217, the first packing member 231 is inserted into the outer peripheral surface of the connecting portion 219 of the frame member 217 in a frictional state. Part of the surface may fall off from the first packing member 231 or the like at the left part, and dust may be generated.

  In this case, for example, as shown in FIG. 8, when the connection structure (seal structure) does not include the second packing member 232, the connection portion 223 of the filter unit 14 is fitted to the outer peripheral side of the first packing member 231. In this state, dust that remains between the first packing member 231 and the base end side wall surface 221 a of the coupling portion 223 of the filter unit 14 enters the supply path 218. As described above, when dust enters the supply path 218, the nozzle 204 arrives together with the recording liquid and clogging occurs.

  Similarly, after the first packing member 231 is first attached to the connecting portion 223 of the filter unit 102, the connecting portion 219 of the frame member 217 may be inserted into the inner peripheral side of the first packing member 231. There is a possibility that dust generated by rubbing during insertion may enter the supply path 218.

  On the other hand, by providing the second packing member 232 and forming the sealed space 233 between the first packing member 231 and the second packing member 232, the connecting portion 223 and the frame member of the filter unit 102 are formed. When connecting the connecting portion 219 of 217, dust generated by the first packing member 231 being frictionally inserted is trapped in the sealed space 233, so that foreign matter such as dust is trapped in the supply path 218. Intrusion can be prevented, and nozzle clogging can be avoided.

  Here, since the second packing member 232 has a function of preventing dust from being mixed in, the sealing performance is not required to seal the recording liquid. Therefore, the second packing member 232 is sandwiched between the distal end portion of the connecting portion 219 of the frame member 217 and the proximal end side wall surface 221a of the connecting portion 223 of the filter unit 14, and simply does not cause friction and has a weak force. Any material that can be crushed to form the sealed space 233 with an elastic restoring force may be used. On the other hand, since the first packing member 231 is interposed between the outer peripheral surface of the connecting portion 219 of the frame member 217 and the inner peripheral surface of the connecting portion 223 of the filter unit 14, a function of sealing the recording liquid is required. The amount of crushed rubber and the nip width must be increased. However, by using a structure that seals in the radial direction as in the present invention, sufficient sealing performance can be obtained only by the elastic repulsive force of the first packing member 231. Easy to maintain.

  Thus, at least one of the liquid discharge head and the filter unit has a tubular connecting portion, and the other has a connecting portion that fits on the outer peripheral side of the tubular connecting portion, and one tubular connecting portion and the other connecting portion. Is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and a direction different from the radial direction, and a sealed space is formed between these two sealing portions. Therefore, both the recording liquid seal and the dust seal can be performed, and the liquid discharge head and the filter unit can be easily sealed while suppressing the entry of dust into the recording liquid supply path.

Next, another different example of the connection structure of the liquid discharge head and the filter unit will be described with reference to FIGS.
In the second embodiment shown in FIG. 4, a single packing member (sealing member) 241 forms the sealing portion by the first packing member 231 and the sealing portion by the second packing member 232 described above. This is an example.

That is, the packing member 241 is a first seal that seals the connecting portion 223 that is the first connecting portion of the filter unit 102 and the connecting portion 219 that is the second connecting portion of the frame 217 of the liquid ejection head 101 in the radial direction. It has a stop part 241a and a second sealing part 241b that seals in a direction (surface direction) different from the radial direction, and is sealed between the first sealing part 241a and the second sealing part 241b in the mounted state. A space 243 is formed. In this case, the first sealing portion 241a performs a recording liquid seal by a radial seal, and the second sealing portion 241b performs a dust seal.

  Thus, by providing at least two sealing portions in the radial direction and a direction different from the radial direction in a single sealing member, the number of parts can be reduced and the cost can be reduced.

  In the third embodiment shown in FIG. 5, the outer peripheral side of the distal end portion 219 a of the connecting portion 219 of the frame 217 of the liquid ejection head 101 and the inner peripheral surface side of the distal end portion 223 a of the connecting portion 223 of the filter unit 102 are respectively tapered. This is an example of a truncated cone shape as a whole.

  With this configuration, when the packing member 241 is mounted, or when the connecting portion 219 of the frame 217 and the connecting portion 223 of the filter unit 102 are connected, the packing member 241 is connected to the connecting portion 219 of the frame 217 or the filter. Since the region that rubs with the connecting portion 223 of the unit 102 can be narrowed, the amount of dust generated can be reduced.

  The fourth embodiment shown in FIG. 6 is an example in which a thin rib 241 c that contacts and deforms the distal end surface of the connecting portion 219 of the frame 217 is formed on the entire circumference of the second sealing portion 241 of the packing member 241. By forming such a rib 241c, an external force necessary for sealing can be reduced. It should be noted that the same effect can be obtained by forming a rib on the front end surface of the connecting portion 219 of the frame 217 instead of forming the rib on the packing member 241.

  In the fifth embodiment shown in FIG. 7, as in the third embodiment, the outer peripheral surface side of the distal end portion 219 a of the coupling portion 219 of the frame 217 of the liquid ejection head 101 and the distal end portion 223 a of the coupling portion 223 of the filter unit 102. The inner peripheral surface side is tapered and formed into a truncated cone shape as a whole, and the packing member 241 formed with the ribs 241c described in the fourth embodiment is used as a sealing member. And the external force required for sealing can be reduced.

In the above description, the configuration in which the filter unit is directly connected (connected) to the frame member of the liquid discharge head has been described. However , the present invention may be a connecting portion that connects different members to communicate the liquid supply path. The present invention can be applied in the same manner, and is particularly effective when connecting a member on the downstream side of the filter and the liquid discharge head. For example, the present invention can be similarly applied to a connection (connection) structure in which a filter unit is provided on the ink cartridge or sub tank side and the supply port of the ink cartridge or sub tank is connected to the supply path of the liquid discharge head.

Next, specific examples and comparative examples will be described.
[Liquid discharge head]
A plurality of piezoelectric elements 212 are obtained by bonding and fixing a piezoelectric element block to be a laminated piezoelectric element 212 with an anaerobic adhesive on a support substrate 13 made of stainless steel, and dividing the piezoelectric element block at a pitch of about 85 μm by a groove processing by a dicing saw. The FPC 220 was bonded to the side surface of the piezoelectric element 212. Further, the nozzle plate 3 and the diaphragm 2 are both manufactured by Ni electroforming, and the flow path plate 211 forming the pressurized liquid chamber 216 and the like is positioned with high accuracy by etching the silicon substrate, and each is made of epoxy adhesive. Was laminated and joined. Next, the diaphragm 212, the piezoelectric element 212, and the frame member 217 made of epoxy resin were bonded and fixed with an epoxy adhesive, and the liquid discharge head 101 was assembled.

[Filter unit]
A filter unit 102 was manufactured by fixing a filter 222 made of a sintered body of SUS wire having a filtration accuracy of 10 μm to a POM case (frame member) 221 by heat fusion.

[Comparative Example]
As shown in FIG. 8, an O-ring 231 having a wire diameter of φ1 made of fluororubber having a rubber hardness of 70 degrees was attached to the connecting portion 219 of the frame member 217, and the connecting portion 223 of the filter unit 102 was connected (connected). The O-ring 231 was configured to collapse 0.35 μm in the radial direction in the mounted state.

  As a result of assembling a large number of head units 100 ′ in this process, connecting the ink to an ink cartridge (not shown) to the filter unit 102, and supplying ink, and performing ejection evaluation, a defect of defective ejection occurred at a frequency of about 2%. .

  Here, when the failure analysis of the head that caused the discharge failure was performed, it was found that the nozzle 204 was mostly clogged with foreign matter, and as a result of material analysis, it was found that most of it was fluororubber.

  Therefore, when the surface of the connecting portion 219 of the frame member 217 immediately before connecting the filter unit 102 is observed, a small number of fluoro rubber pieces are attached to the portion indicated by symbol B in FIG. It was confirmed.

  Therefore, after attaching the O-ring 231 to the connecting portion 219 of the frame member 217, the portion where the O-ring 231 was frictionally inserted was washed, and the filter unit 102 was connected and the injection evaluation similar to the above was performed. It was confirmed that the incidence of

[Example 1]
As shown in FIG. 3, after an O-ring (first packing member) 231 is connected to the connecting portion 219 of the frame member 217, a silicone rubber packing having a rubber hardness of 40 degrees and a thickness of 1.5 mm (second The connecting portion 223 of the filter unit 102 was connected via a packing member 232.

  Then, the same injection evaluation as in the comparative example was performed. As a result, the portion where the O-ring 231 was frictionally inserted after the O-ring 231 was attached to the connecting portion 219 of the frame member 217 was cleaned without cleaning. It was confirmed that the defective rate was reduced.

[Example 2]
The connecting portion 219 of the frame member 217 and the connecting portion 223 of the filter unit 102 are connected using the packing member 241 of the second embodiment shown in FIG. Here, the material of the packing member 241 is fluororubber having a rubber hardness of 60 degrees, the dimension of the substantially circular cross-sectional shape of the first sealing portion 241a (dimension D in FIG. 4) is 1 mm, and the thickness of the second sealing portion 241c ( The dimension C) in FIG. 4 was 1.5 mm.

  When the same injection evaluation as that of Example 1 was performed, the occurrence rate of ejection failure was equivalent to that of Example 1.

Example 3
The connecting portion 219 of the frame member 217 and the connecting portion 223 of the filter unit 102 are connected using the packing member 241 of the fifth embodiment shown in FIG. Here, the material of the packing member 241 is fluororubber having a rubber hardness of 60 degrees, the dimension of the substantially circular cross-sectional shape of the first sealing portion 241a (dimension D in FIG. 4) is 1.2 mm, and the second sealing portion 241c The thickness (dimension C in FIG. 4) was 1 mm, and the ribs 241c formed on the entire circumference corresponding to the tip surface of the connecting portion 219 had a width of 0.5 mm and a height of 0.3 mm. Further, a taper surface of 5 degrees was formed on each of the connecting portion 219 of the frame member 217 and the front end portions 219a and 223a of the connecting portion 223 of the filter unit 102.

  The connecting portion 219 of the frame member 217 and the tip end portions 219a and 223a of the connecting portion 223 of the filter unit 102 are formed with tapered surfaces of 5 degrees, respectively, so that the region where the packing member 241 is rubbed during connection is reduced. It was confirmed that the property was improved and the dust due to friction was reduced.

  Moreover, when the injection evaluation similar to Example 1 was implemented, the discharge defect incidence rate was the same as the evaluation in Example 1. Furthermore, it was confirmed that the force which crushes the packing member 241 can be reduced because the packing member 241 has the rib 241c.

1 is an explanatory side view illustrating an overall configuration of an image forming apparatus according to the present invention. It is a plane explanatory view of the mechanism part. FIG. 3 is a cross-sectional explanatory view illustrating a first embodiment of a connection structure of a liquid discharge head and a filter unit. It is principal part sectional explanatory drawing which similarly shows 2nd Embodiment. It is principal part sectional explanatory drawing which similarly shows 3rd Embodiment. It is principal part sectional explanatory drawing which similarly shows 4th Embodiment. It is principal part sectional explanatory drawing which similarly shows 5th Embodiment. It is sectional explanatory drawing which shows the connection structure of the liquid discharge head and filter unit of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 ... Carriage 11 ... Recording head 15 ... Sub tank 100 ... Head unit 101 ... Liquid discharge head 102 ... Filter unit 201 ... Channel plate 217 ... Frame member 218 ... Supply path 219 ... Connection part 221 ... Case 222 ... Filter 223 ... Connection part 231 ... 1st packing member 232 ... 2nd packing member 233 ... Sealed space 241 ... Packing member 241a ... 1st sealing part 241b ... 2nd sealing part 241c ... Rib 243 ... Sealed space

Claims (4)

In an image forming apparatus in which a liquid discharge head having a nozzle for discharging a recording liquid droplet is connected to a filter unit including a filter for filtering a recording liquid supplied to the liquid discharge head.
A tubular connection part is provided on at least one of the liquid discharge head and the filter unit, and a connection part fitted on the outer peripheral side of the tubular connection part on the other side;
Between the one tubular connecting portion and the other connecting portion is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and a direction different from the radial direction, and these two connecting portions A sealed space is formed between the sealing parts ,
An image forming apparatus , wherein a rib is formed on a sealing member constituting a sealing portion in a direction different from the radial direction or on a connecting portion side facing the sealing member . A liquid discharge head having a nozzle for discharging recording liquid droplets is connected to a member separate from the liquid discharge head and downstream of the filter means for filtering the recording liquid supplied to the liquid discharge head. In the image forming apparatus,
A tubular connecting part is fitted to at least one of the members downstream from the liquid discharge head and the filter means, and the other has a connecting part fitted to the outer peripheral side of the tubular connecting part;
Between the one tubular connecting portion and the other connecting portion is sealed with at least two sealing portions in the radial direction of the tubular connecting portion and a direction different from the radial direction, and these two connecting portions A sealed space is formed between the sealing parts,
An image forming apparatus , wherein a rib is formed on a sealing member constituting a sealing portion in a direction different from the radial direction or on a connecting portion side facing the sealing member . In an image forming apparatus in which a liquid discharge head having a nozzle for discharging a recording liquid droplet is connected to a filter unit including a filter for filtering a recording liquid supplied to the liquid discharge head.
A first connecting portion of the tubular hand of the liquid ejection head and the filter unit, a second connection part fitted on the outer peripheral side of the first connecting portion to the other,
A sealing member for sealing between the first connecting portion and the second connecting portion ;
The sealing member includes a first sealing portion that seals a gap between the first connecting portion and the second connecting portion in a radial direction, a tip surface of the first connecting portion, and the second connecting portion. A second sealing portion that seals the gap in the plane direction,
The sealing member includes a first packing member having an O-ring-shaped first sealing portion formed at a front end portion, and a plate-like second sealing portion that is continuous with a rear end of the first packing member. And a second packing member forming
An image forming apparatus , wherein a sealed space is formed between the first sealing portion and the second sealing portion of the sealing member . A liquid discharge head having a nozzle for discharging recording liquid droplets is connected to a member separate from the liquid discharge head and downstream of the filter means for filtering the recording liquid supplied to the liquid discharge head. In the image forming apparatus,
A tubular first connecting portion on one of the members downstream of the liquid discharge head and the filter means, and a second connecting portion fitted on the outer peripheral side of the first connecting portion on the other;
A sealing member for sealing between the first connecting portion and the second connecting portion;
The sealing member includes a first sealing portion that seals a gap between the first connecting portion and the second connecting portion in a radial direction, a tip surface of the first connecting portion, and the second connecting portion. A second sealing portion that seals the gap in the plane direction,
The sealing member includes a first packing member having an O-ring-shaped first sealing portion formed at a front end portion, and a plate-like second sealing portion that is continuous with a rear end of the first packing member. And a second packing member forming
A sealed space is formed between the first sealing portion and the second sealing portion of the sealing member.
An image forming apparatus.

Images