JP2007015153A - Image forming device and negative pressure maintenance control method in image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that image quality deteriorates and a recording liquid leaks sometimes from a head at the time when the inflow of the recording liquid causing air and negative pressure drop in a sub tank causes a negative pressure abnormality. <P>SOLUTION: The image forming device displaceably has a negative pressure sensing lever 106 which displaces in accordance with negative pressure in a sub tank 35, and performs the action of recovering negative pressure to return the negative pressure of the sub tank 35 to the normal condition by detecting the causing of a negative pressure abnormality in the sub tank 35 by sensing the opening of the negative pressure sensing lever 106 in performing the action of filling the sub tank 35 with an ink by absorbing the ink from the corresponding nozzles of the recording head 34 in accordance with the amount of opening of the negative pressure sensing lever 106 when the negative pressure abnormality has occurred in the sub tank 35 by the opening of the negative pressure sensing lever 106. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a negative pressure maintenance control method in the image forming apparatus.

  In general, as an image forming apparatus that combines a printer / fax / copier or a combination of these functions, an image forming unit that employs an electrophotographic method is known. For example, liquid discharge that discharges liquid droplets of recording liquid is known. Recording is performed while a recording medium (hereinafter also referred to as “paper” is not limited to a material, and the recording medium, a transfer material, and the like are also used synonymously) using a recording head constituted by a head. Some are equipped with an image forming unit of an ink jet system that performs image formation (recording, printing, printing, and printing are also used synonymously) by attaching liquid droplets (hereinafter also referred to as ink droplets) to paper. is there.

  In such an ink jet recording type image forming apparatus, a sub-tank, which is a small-capacity recording liquid container for supplying a recording liquid to a recording head, is mounted on a carriage, and a large-capacity main cartridge (main tank) is mounted on the apparatus main body side. There is known an apparatus that is installed and replenished with a recording liquid (ink) supplied from a main cartridge on the apparatus main body side to a sub tank.

As such a sub-tank, as described in Patent Document 1, a case with an open side wall, a film that covers the opening of the case, and an elastic member that presses the film from the inside through a plate, And a negative pressure lever that is a plate-like elastic member that urges the film back to be pushed back from the outside, and the balance of the pressing force between the negative pressure lever and the inner elastic member corresponds to the fluctuation of the internal pressure of the sub tank. It is known that when the amount of ink in the sub-tank decreases, the film is pushed back inward as the internal pressure changes.
JP 2003-231275 A

  By the way, in order to prevent the recording liquid from seeping out and sagging from the nozzles of the recording head, the sub-tank must always maintain a certain negative pressure above a certain level. Compared with the mechanism mounted on the apparatus, there is a possibility that air will flow in because a connecting portion of the tube for supplying the recording liquid from the apparatus main body side exists. If air flows into the sub-tank, the pressure inside the recording head becomes positive, and the image quality deteriorates due to a drop in droplet discharge performance, or the recording liquid flows out of the recording head due to its own weight. Become.

Therefore, conventionally, for example, in Patent Document 2, a pressure sensor is mounted between the ink cartridge and the recording head at a location away from the intermediate tank, and the negative pressure inside the recording head is sensed. A configuration is described in which a desired negative pressure is maintained by moving the intermediate tank up and down.
Japanese Patent Laid-Open No. 2003-341028

Further, in Patent Document 3, when the pressure of the main tank chamber is reduced by consuming ink from the sub tank chamber having the meniscus constituent member attached to the main tank chamber for storing ink, the reduced pressure A configuration is described in which ink is automatically supplied from the sub-tank chamber to maintain a desired negative pressure.
Japanese Patent No. 3269268

Further, in Patent Document 4, a sealed ink tank is filled with ink, and a small hole whose one end is opened to the atmosphere is provided in the ink tank. When the ink in the ink tank is consumed, the air passes through the small hole. A configuration is described in which a desired negative pressure is maintained in the ink tank supplied to the tank.
Japanese Patent No. 2898746

  However, in the configuration described in Patent Document 1, since the recording head, the intermediate tank, and the pressure sensor are disposed at separate locations, a mechanism for moving the intermediate tank up and down is required. There is a problem that the configuration is complicated and large.

  In the configuration described in Patent Document 2, it is difficult to maintain a desired negative pressure due to deterioration of the meniscus constituent member. Moreover, when the tank itself leaks for some reason, there is a problem that it is impossible to cope with the malfunction.

  In the configuration described in Patent Document 3, since it is always open to the atmosphere, there is a problem that degeneration of ink occurs, and it is impossible to cope with the case where the subtank leaks for some reason.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of recovering a negative pressure in a sub-tank with a simple configuration and a negative pressure maintaining control method for the image forming apparatus. And

  In order to solve the above-described problem, an image forming apparatus according to the present invention supplies a recording liquid to a recording head that discharges droplets of the recording liquid from a nozzle and replenishes and supplies the recording liquid from a main tank on the apparatus body side. A means for detecting a negative pressure state in the sub tank is provided, and a means for performing a negative pressure recovery operation for returning the negative pressure to a normal state when an abnormality in the negative pressure in the sub tank is detected.

  Here, the negative pressure recovery operation preferably includes an operation of capping the recording head and sucking the recording liquid from the nozzle. In this case, it is preferable to perform an operation of recovering the negative pressure by capping the recording head and sucking the recording liquid from the nozzle only when a recording liquid that causes a negative pressure drop flows into the sub tank. In the operation of capping the recording head and sucking the recording liquid from the nozzle, it is preferable to suck the recording liquid in accordance with the amount of the recording liquid that causes the negative pressure drop flowing into the sub tank. Furthermore, it is preferable that the negative pressure recovery operation includes an operation of reopening the inside of the sub tank to the atmosphere and regenerating the negative pressure.

  Further, the negative pressure recovery operation preferably includes an operation of sucking air in the sub tank. In this case, it is preferable to perform the operation of sucking the air in the sub tank and recovering the negative pressure only when the air flows into the sub tank. Further, in the operation of sucking air in the sub tank, it is preferable to suck air corresponding to the amount of air flowing into the sub tank.

  Furthermore, it is preferable to provide means for detecting the inflow of recording liquid that causes a decrease in air or negative pressure into the sub tank. In this case, it is preferable that the means for detecting the inflow of air or recording liquid is a lever that is displaced according to the pressure in the sub tank. In addition, it is preferable to perform an operation of detecting an inflow of recording liquid that causes a decrease in air or negative pressure to the sub tank when performing an operation of replenishing and supplying the recording liquid to the sub tank. Furthermore, it is preferable to perform the operation of recovering the negative pressure only for the recording head in which the abnormality of the negative pressure is detected when performing the maintenance recovery operation for the plurality of recording heads.

  The negative pressure maintaining control method in the image forming apparatus according to the present invention is configured to perform a negative pressure maintaining operation for returning the negative pressure to a normal state when an abnormality in the negative pressure in the sub tank is detected.

  According to the image forming apparatus and the negative pressure maintaining control method in the image forming apparatus according to the present invention, when the abnormality of the negative pressure in the sub tank is detected, the negative pressure maintaining operation for returning the negative pressure to a normal state is performed. With this configuration, the negative pressure in the sub tank can be restored to a normal state, and the deterioration of image quality and the outflow of the recording liquid from the recording head can be prevented.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory perspective view of an ink jet recording apparatus as an image forming apparatus according to the present invention as viewed from the front side.
The ink jet recording apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper loaded in the apparatus main body 1, and a paper on which an image is recorded (formed) detachably mounted on the apparatus main body 1. A paper discharge tray 3 for stocking is provided. Furthermore, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). The cartridge loading unit 4 has an operation / display unit 5 provided with operation buttons and a display.

  The cartridge loading unit 4 contains a plurality of recording liquids (inks) that are different color materials, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink. Ink cartridges 10k, 10c, 10m, 10y (referred to as “ink cartridge 10” when colors are not distinguished) from the front side to the rear side of the apparatus main body 1 A front cover (cartridge cover) 6 that is opened when the ink cartridge 10 is attached or detached is provided on the front side of the cartridge loading portion 4 so as to be openable and closable. Further, the ink cartridges 10k, 10c, 10m, and 10y are configured to be loaded side by side in a vertical state.

  Further, the operation / display unit 5 has the remaining amounts of the ink cartridges 10k, 10c, 10m, and 10y of each color at the arrangement positions corresponding to the mounting positions (arrangement positions) of the ink cartridges 10k, 10c, 10m, and 10y of the respective colors. The remaining amount display portions 11k, 11c, 11m, and 11y for each color for displaying the near end and the end are arranged. Further, the operation / display unit 5 is also provided with a power button 12, a paper feed / print resume button 13, and a cancel button 14.

Next, the mechanism part of the ink jet recording apparatus will be described with reference to FIGS. FIG. 3 is a schematic side view illustrating the outline of the mechanism, and FIG.
A carriage 33 is slidably held in the main scanning direction by a guide rod 31 which is a guide member horizontally mounted on the left and right side plates 21A and 21B constituting the frame 21, and a stay 32, and a timing belt is held by a main scanning motor (not shown). 3 is moved and scanned in the direction indicated by the arrow (carriage main scanning direction) in FIG.

  As described above, the carriage 33 includes a recording head 34 including four droplet discharge heads that discharge ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk). A plurality of ink ejection openings are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  As an inkjet head constituting the recording head 34, 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 34 and is connected to a control unit (not shown) via a harness (flexible print cable) 22.

  In addition, the carriage 33 is equipped with a sub tank 35 for each color for supplying ink of each color to the recording head 34. As described above, each color sub-tank 35 is supplementarily supplied with ink of each color from the ink cartridge 10 of each color mounted in the cartridge loading unit 4 via the ink supply tube 36 of each color. The cartridge loading 4 is provided with a supply pump unit 24 for feeding ink in the ink cartridge 10, and the ink supply tube 36 is engaged with the rear plate 21 </ b> C constituting the frame 21 in the middle of turning. It is held by a stop member 25.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a holding belt 48 which is a conveying means for electrostatically attracting the fed paper 42 and conveying it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. Further, a guide member 57 is disposed on the back side of the conveyor belt 51 in correspondence with a printing area by the recording head 34.

  The transport belt 51 rotates in the belt transport direction of FIG. 3 when the transport roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a paper discharge roller 63 are provided. The paper discharge tray 3 is provided below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 3, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the state of the nozzles of the recording head 34 is arranged in the non-printing area on one side of the carriage 33 in the scanning direction. Yes.

  The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a to 82d (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper blade 83 that is a blade member for wiping the ink, and an empty discharge receiver 84 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing. Here, the cap 82a is a suction and moisture retention cap, and the other caps 82b to 82d are moisture retention caps.

  Then, the waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 81, the ink discharged to the cap 82, the ink attached to the wiper blade 83 and removed by the wiper cleaner 85, and the idle ejection to the idle ejection receiver 94. The discharged ink is discharged and stored in a waste liquid tank (not shown).

  Further, as shown in FIG. 3, in the non-printing area on the other side in the scanning direction of the carriage 33, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An empty discharge receiver 88 for receiving the droplets at the time is disposed, and the empty discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the recording head 34.

  In the ink jet recording apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and the transport belt 51 and the counter roller 46, and the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the tip pressing roller 49, and the conveying direction is changed by approximately 90 °.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control unit, which will be described later, to the charging roller 56, that is, an alternating voltage is applied, and the conveying belt 51 alternates. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 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 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, during printing (recording) standby, the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the recording head 34 is capped by the cap 82 to keep the nozzles in a wet state, thereby preventing ejection failure due to ink drying. . Further, the recording liquid is sucked from the nozzle by a suction pump (not shown) with the recording head 34 capped by the cap 82 (referred to as “nozzle suction” or “head suction”), and the thickened recording liquid and bubbles are discharged. Perform recovery action. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

  Next, an example of the sub tank 35 in the image forming apparatus will be described with reference to FIGS. 4 is an external perspective view of the sub-tank, FIG. 5 is an exploded perspective view of the sub-tank, FIG. 6 is a schematic side view of the sub-tank, and FIG. 7 is a schematic cross-section along the line AA in FIG. It is explanatory drawing.

  The sub tank 35 is a flexible film that seals an opening (one surface of the sub tank 15) of the ink storage unit 100 to a container main body (case main body) 101 that forms the ink storage unit 100 that stores ink as a recording liquid. A film-like member (flexible film-like member) 102 is attached by adhesion or welding, and the film-like member 102 is urged outwardly between the case main body 101 and the film-like member 102 inside the ink containing portion 100. A spring (spring) 103 is provided as an elastic member.

  Here, the film-like member 102 may have a single-layer configuration, but may have a two-layer configuration in which different types of first and second layers are laminated, for example, a configuration in which polyethylene and nylon film-like members are laminated, It can be set as the structure which formed the silica vapor deposition layer in the layer. By configuring the film-like member 102 to have two or more different types of layers, it is possible to improve the liquid resistance against the ink to be stored. In this case, by adopting a laminated structure of polyethylene and nylon, it is possible to reliably ensure liquid resistance against ink. Moreover, the liquid resistance with respect to the ink accommodated can also be improved by including a silica vapor deposition layer in the film-like member 102.

  Furthermore, a bulging portion 102a having a convex shape corresponding to the spring 103 is formed on the film-like member 102, and a reinforcing member 104 is attached to the outer surface thereof. In this manner, by providing the flexible film-like member 102 with the convex portion, the elastic member (here, the spring) 103 can be stably held. In this case, the flexible film-like member 102 can be easily formed with a convex portion by forming a sheet-like film member into a convex shape.

  A negative pressure detection lever 106 that is displaced according to the displacement of the film-like member 102 is swingably attached to support portions 107 and 107 provided on the side of the case 101.

  In addition, the case 101 is provided with an ink introduction path 111 for replenishing ink in the ink containing part 100, and a connecting means for connecting the ink introduction path 111 and the supply tube 36 connected to the ink cartridge 10. 112 can be detachably mounted.

  Further, a connecting member 113 for supplying ink from the ink storage unit 100 to the recording head 34 is attached to the lower part of the case 101, and an ink supply path 114 of the recording head 34 is formed in the connecting member 113, so A filter 115 is interposed between the two.

  An air flow path 121 is formed in the upper part of the case 101 for taking out air from the ink containing portion 100. The air flow path 121 includes an inlet flow path portion 122 whose opening faces the ink containing portion 100 and a flow path portion 123 following the inlet flow path portion 122, and an air opening hole 131 provided in the case 101 on the downstream side. In addition, an accumulation portion 126 is continuously formed in a portion that is lower than the atmosphere opening hole 131 in the use state.

  The atmosphere release hole 131 is provided with an atmosphere release valve mechanism 132 which is an atmosphere release means for switching between the sealed state and the atmosphere release state in the sub tank 35. The atmosphere release valve mechanism 132 is configured by accommodating a valve seat 134, a ball 135 as a valve body, and a spring 136 for urging the ball 135 toward the valve seat 134 in a holder 133.

  In addition, two detection electrodes for detecting that the amount of gas (air) in the sub-tank 35 has become a predetermined amount or more (or that the remaining amount of ink has become a predetermined amount or less) is provided above the case 101. 141 and 142 are attached. The amount of gas (or the amount of ink) is changed by changing the conduction state between the detection electrodes 141 and 142 in a state where both the detection electrodes 141 and 142 are immersed in ink and in a state where at least one of the detection electrodes 141 and 142 is not immersed in ink. ) Can be detected.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. This figure is an overall block diagram of the control unit.
The control unit 300 includes a main control unit 301 configured by a microcomputer that also serves as a negative pressure maintenance control unit that controls the entire image forming apparatus, and a print control unit 302 configured by a microcomputer that controls print control. ing.

  The main control unit 301 then forms a main scanning motor in order to form an image on the paper 42 based on information such as print data input from the communication circuit 101 from a host 400 such as a personal computer equipped with the printer driver 401. Drive 201 and sub-scanning motor 205 are controlled via main scanning motor drive circuit 303 and sub-scanning motor 304, and control such as sending print data to print control unit 302 is performed.

  The main control unit 301 receives a detection signal from a carriage position detection circuit 305 that detects the position of the carriage 33, and the main control unit 301 controls the movement position and movement speed of the carriage 33 based on the detection signal. To do. The carriage position detection circuit 305 detects the position of the carriage 33 by, for example, reading and counting the number of slits of an encoder sheet arranged in the scanning direction of the carriage 33 with a photosensor mounted on the carriage 33. The main scanning motor drive circuit 303 rotates the main scanning motor 201 according to the carriage movement amount input from the main control unit 301 to move the carriage 33 to a predetermined position at a predetermined speed.

  Further, the main control unit 301 receives a detection signal from a conveyance amount detection circuit 306 that detects the movement amount of the conveyance belt 51, and the main control unit 301 moves the movement amount and movement speed of the conveyance belt 51 based on the detection signal. To control. The conveyance amount detection circuit 306 detects the conveyance amount by, for example, reading and counting the number of slits of the rotary encoder sheet attached to the rotation shaft of the conveyance roller 52 with a photo sensor. The sub-scanning motor driving circuit 304 rotates the sub-scanning motor 205 in accordance with the conveyance amount input from the main control unit 301 and rotationally drives the conveyance roller 52 to move the conveyance belt 51 to a predetermined position at a predetermined speed. Move with.

  The main control unit 301 rotates the sheet feeding roller 43 once by giving a sheet feeding roller driving command to the sheet feeding roller driving circuit 307. The main control unit 301 drives the motor 191 through the maintenance / recovery mechanism driving motor drive circuit 308 to move the cap 82 up and down and the wiper blade 83 up and down.

  The main control unit 301 drives and controls the ink supply motor for driving the pump of the supply unit 24 via the ink supply motor drive circuit 311, and the ink cartridge 10 loaded in the cartridge loading unit 4 controls the sub tank 35. Supply ink.

  When the main controller 301 supplies the ink to the sub tank 35 with the carriage 33 at the position of the maintenance / recovery mechanism 81, the negative pressure detection lever 106 of the sub tank 35 is in a full tank state. A detection signal from the sub tank full sensor 312 that detects that the sub tank 35 is full by detecting the displacement to the position, and a detection signal from the cartridge cover sensor 312 that detects opening and closing of the front cover 6 of the cartridge loading unit 4. A detection signal is input.

  In addition, the main control unit 301 stores, through the cartridge communication circuit 314, non-volatile memories 115k, 115c, 115m, and 115y that are storage units provided in the respective ink cartridges 10 attached to the cartridge loading unit 4 (“nonvolatile” if not distinguished) The information stored in the volatile memory 115 ") is taken in, required processing is performed, and the information is stored and held in a non-volatile memory (for example, EEPROM) 315 as a main body storage means.

  Here, the remaining amount of the ink cartridge 10 is detected by reading out the remaining amount information stored in the non-volatile memory 115 of the ink cartridge 10 and temporarily storing it in the non-volatile memory 315 on the main body side. The number of ejected droplets from the ink is counted, the ink amount used is calculated based on the count value, and the new ink remaining amount obtained based on the ink remaining amount and the ink amount used is subtracted from the ink cartridge 10 for each printing. Each time ink is supplied to the ink cartridge 35, the data is written in the nonvolatile memory 115 of the ink cartridge 10. Then, the remaining amount of ink stored in the nonvolatile memory 115 of the ink cartridge 10 is read to detect the absence of ink (ink end or ink near end).

  The print control unit 302 ejects droplets of the recording head 34 (recording head 134) based on the signal from the main control unit 301 and the carriage position and conveyance amount from the carriage position detection circuit 305 and the conveyance amount detection circuit 306. Data for driving the pressure generating means is generated and applied to the head drive circuit 310.

  The head drive circuit 310 drives the pressure generating means (piezoelectric element in the case of a piezo head) of the recording head 34 based on the print data from the print control unit 302, and discharges droplets from a required nozzle.

  Further, the main control unit 301 stores and holds the usage amount of the color material (ink) and the number of printed sheets in the non-volatile memory (for example, EEPROM) 315 as statistical information (statistical data), and based on the remaining amount of ink and the number of printed sheets. When a request for the number of printable sheets is made through the printer driver 401 of the host 400, a process for responding to the host 400 side with information on the number of printable sheets relating to the number of sheets that can be printed with the current ink remaining amount and information on the remaining amount of ink is performed. In response to the response from the image forming apparatus, the printer driver 401 displays the number of printable sheets and the like through the print properties of the host 400.

Therefore, a first embodiment in which the present invention is applied to such an image forming apparatus will be described with reference to FIG.
In this embodiment, as described above, ink is replenished and supplied from the ink cartridge 10 to the sub tank 35 via the supply tube 26 by the supply pump 241 of the supply unit 24.

  Further, the surface (nozzle surface) on which the nozzles of the recording head 34 are formed is capped by the suction cap 82a of the maintenance / recovery mechanism 81, and the suction pump 811 of the maintenance / recovery mechanism 81 is driven so that the nozzle can be removed from the nozzles via the suction tube 812. The ink in the sub tank 35 can be sucked by sucking the ink. The sucked waste ink is discharged to a waste liquid tank 813.

  Further, the negative pressure detection lever 106 of the sub tank 35 changes in accordance with the negative pressure state of the sub tank 35, and the opening amount of the negative pressure detection lever 106 is detected by the full tank detection sensor 312 and detected by the full tank detection sensor 312. When the negative pressure detection lever 106 is opened, the supply pump 241 or the suction pump 811 is driven by the control unit 301 to perform negative pressure maintenance control (negative pressure recovery operation is performed to restore the negative pressure of the sub tank 35 to a normal state. Control).

The negative pressure maintenance control in this embodiment will be described with reference to FIGS.
First, the controller 300 also starts the negative pressure maintenance control operation when starting the ink filling operation to the sub tank 35, detects the opening amount of the negative pressure detection lever 106, and opens the negative pressure detection lever 106 ( Whether negative pressure is abnormal) is determined.

  For example, as shown in FIG. 11A, when the sub tank 35 is moved by moving the carriage 33 in a direction indicated by an arrow in order to perform the ink filling operation for the sub tank 35, the negative pressure of the sub tank 35 is decreased. If the pressure is normal, the negative pressure detection lever 106 has moved to the sub tank 35 side, and therefore the full pressure detection sensor 312 can detect the negative pressure detection lever 106 when it has moved by the distance X1.

  On the other hand, as shown in FIG. 11B, if the negative pressure of the sub tank 35 is abnormal, the negative pressure detection lever 106 that should have moved to the sub tank 35 side is separated from the sub tank 35 (elasticity). Since the member 103 is pushed outward by the restoring force of the member 103, the full pressure detection sensor 312 detects the negative pressure detection lever 106 when the distance X2 is shorter than the distance X1. .

  Therefore, the opening amount of the negative pressure detection lever 106 can be detected based on the moving distance of the sub tank 35. By converting the opening amount of the negative pressure detection lever 106 into a negative pressure value inside the sub tank 35 in advance, Abnormal negative pressure can be detected during ink filling operation.

  Here, when no negative pressure abnormality is recognized, ink filling is started as it is, a required amount of ink is filled, and ink filling is terminated.

  On the other hand, if an abnormality is detected in the opening amount of the negative pressure detection lever 106 during the ink filling operation, that is, if there is an abnormality in the negative pressure in the sub tank 35, the opening amount is a predetermined opening amount a. It is determined whether it is within the range of ˜b or within the range of the opening amount b to c (a ≦ b ≦ c), that is, the degree of the opening amount.

  When the opening amount is within the predetermined opening amounts a to b, the suction pump 812 is operated with the recording head 34 capped by the cap 82a to suck a predetermined amount of ink from the nozzles of the recording head 34. The operation is performed once. Thereby, as described above, the negative pressure in the sub tank 35 can be restored to a normal state by the restoring force of the elastic member 103.

  When the opening amount is within the range of the predetermined opening amounts b to c, the suction pump 812 is operated with the recording head 34 capped by the cap 82a to suck a predetermined amount of ink from the nozzles of the recording head 34. The operation is performed twice. As a result, the amount of ink sucked is larger than that described above, and the negative pressure in the sub tank 35 can be restored to the normal state by the restoring force of the elastic member 103 as described above.

  That is, the opening amount of the negative pressure detection lever 106 depends on the degree of abnormality of the negative pressure of the sub tank 35, in other words, the amount of air flowing into the sub tank 35 or the amount of ink (unnecessary ink) that causes a negative pressure drop. Then, the ink in the sub tank 35 is sucked.

  In this way, a means for detecting the negative pressure state in the sub tank is provided, and when an abnormality in the negative pressure in the sub tank is detected, a negative pressure recovery operation is performed to return the negative pressure to a normal state. With the configuration, the negative pressure of the sub tank can be maintained in a normal state, and it is possible to prevent the image quality from being deteriorated and to prevent the ink from flowing out from the recording head.

  Here, since the negative pressure recovery operation includes the operation of capping the recording head and sucking the recording liquid from the nozzle, the negative pressure recovery can be performed using the maintenance recovery mechanism of the previous head. It will be easy. In this case, the negative pressure is recovered at an appropriate timing by performing the operation of capping the recording head and sucking the recording liquid from the nozzle to recover the negative pressure only when the recording liquid that causes the negative pressure drop flows into the sub tank. Since the pressure maintaining operation is performed, the negative pressure value inside the sub tank can always be kept normal. Further, in the operation of capping the recording head and sucking the recording liquid from the nozzle, the negative pressure of the sub tank is more accurately obtained by sucking the recording liquid according to the amount of the recording liquid that causes the negative pressure drop flowing into the sub tank. Can be recovered.

  Further, by using a lever (negative pressure detection lever) that is displaced according to the pressure in the sub-tank as means for detecting the inflow of air or the inflow of the recording liquid that causes the negative pressure abnormality in the sub-tank, the pressure is reduced as described later. The configuration is simpler and the cost can be reduced than when using a sensor or the like. Further, by detecting (detecting) an abnormality in the negative pressure in the subtank when performing an operation of replenishing and supplying recording liquid to the subtank, it is possible to prevent a decrease in printing speed due to the detection (detection) operation.

  Here, unlike the case where the maintenance recovery mechanism 81 maintains and recovers the state of each recording head 34, the negative pressure recovery operation for the sub tank 35 is performed only for the sub tank 35 in which the negative pressure abnormality occurs. As a result, it is possible to prevent the unnecessary negative pressure recovery operation from being performed, thereby preventing the printing speed from being lowered and the startup time from becoming unnecessarily long.

Next, a second embodiment to which the present invention is applied will be described with reference to FIG.
The configuration of this embodiment is the same as that of the first embodiment, but differs in that control is applied to the drive unit 321 that operates the atmosphere release mechanism 132 of the sub tank 35 to release the atmosphere. The drive unit 321 that operates the atmosphere release mechanism 132 of the sub tank 35 to release the atmosphere is provided to perform the atmosphere release filling that is used as one of the filling modes when the ink supply to the sub tank 35 is performed. is there.

  The operation of this embodiment will be described with reference to FIG. 13. Here, when an abnormality is detected in the opening amount of the negative pressure detection lever 106 during the ink filling operation, that is, when the negative pressure in the sub tank 35 is abnormal. In order to restore the negative pressure to the normal state, the sub-tank 35 is filled to the atmosphere.

  That is, the inside of the sub tank 35 is opened to the atmosphere by operating the drive unit 321 to open the atmosphere release mechanism 132 of the sub tank 35. In this state, the supply pump 241 is operated to replenish and supply (fill) ink from the ink cartridge 10 into the sub tank 35. In this case, when the sub tank 35 is full, ink filling is started in a state where the sub tank 35 is positioned at a position where the negative pressure detection lever 106 is detected by the full tank detection sensor 312. When 312 detects the negative pressure detection lever 106, ink filling is terminated. Thereafter, the suction pump 812 is operated while the recording head 34 is capped with the cap 82a, and a required amount of ink is sucked from the nozzle, whereby the sub tank 35 is brought into a required negative pressure state by the restoring force of the elastic member 103. (In this case, a negative pressure state is newly generated.) Thereby, the negative pressure of the sub tank 35 in which the negative pressure abnormality has occurred can be recovered to a normal state.

  In this way, when the negative pressure value in the sub tank is abnormal, it is possible to regenerate the desired negative pressure value from the beginning by performing open air filling, so that the normal negative pressure value is maintained (recovered). Can do.

Next, a third embodiment to which the present invention is applied will be described with reference to FIGS.
Here, instead of the negative pressure detection lever 106 described above, a pressure sensor 501 for detecting the pressure in the sub tank 35 is provided.

  Then, as shown in FIG. 15, the negative pressure maintenance control is started and the detection value of the pressure sensor 501 is read to determine whether the detection value by the pressure sensor 501, ie, the negative pressure in the sub tank 35 is normal (abnormal). If the negative pressure in the sub tank 35 is abnormal, the suction pump 812 is operated in a state where the recording head 34 is capped with the cap 82a, and an operation of sucking a predetermined amount of ink from the nozzles of the recording head 34 is performed. Thereby, as described above, the negative pressure in the sub tank 35 can be restored to a normal state by the restoring force of the elastic member 103.

  In other words, by checking the correlation between the pressure in the sub tank 35 and the ink amount in advance and performing the above-described control, when the pressure sensor 501 detects an abnormality when unnecessary ink or air flows into the sub tank 35. A predetermined amount of ink is sucked until the pressure value in the sub tank 35 becomes normal, and the negative pressure in the sub tank 35 can always be recovered and maintained at a desired negative pressure value.

  In this way, it is possible to directly detect whether or not the negative pressure is abnormal by using the pressure sensor that detects or detects the pressure in the sub-tank. When an abnormality is detected, the negative pressure is restored to a normal state. By performing the operation, the negative pressure of the sub-tank can be maintained in a normal state with a simple configuration, so that the image quality can be prevented from being deteriorated and ink can be prevented from flowing out from the recording head.

Next, a fourth embodiment to which the present invention is applied will be described with reference to FIG.
Here, as in the third embodiment, a pressure sensor 501 for detecting the pressure in the sub tank 35 is provided instead of the negative pressure detection lever 106. Further, a suction pump 502 for sucking air in the sub tank 35 is provided.

  Then, as shown in FIG. 17, the negative pressure maintenance control is started and the detection value of the pressure sensor 501 is read to determine whether the detection value by the pressure sensor 501, that is, the negative pressure in the sub tank 35 is normal (abnormal). If the negative pressure in the sub tank 35 is abnormal, the controller 300 drives the suction pump 502 to perform a suction operation of a predetermined amount of air from the sub tank 35. As a result, the negative pressure in the sub tank 35 can be restored to a normal state.

  In this way, when the negative pressure in the sub tank becomes abnormal, the negative pressure can be recovered to a normal value by sucking air instead of sucking ink.

  The configuration of the sub tank is not limited to that of the above embodiment, and any sub tank that can perform a negative pressure recovery operation may be used. The image forming apparatus according to the present invention is not limited to a printer having a single function configuration, and may be an image forming apparatus having a composite function such as a printer / facsimile / copying.

FIG. 3 is a perspective explanatory view seen from the front side of the ink jet recording apparatus as the image forming apparatus according to the present invention. It is a side schematic block diagram explaining the whole structure of the mechanism part of the apparatus. It is principal part plane explanatory drawing of the mechanism part. It is a perspective explanatory view showing an example of a sub tank of the same device. It is a disassembled perspective explanatory view of the sub tank. It is typical side surface explanatory drawing of the same sub tank. It is typical cross-sectional explanatory drawing which follows the AA line of FIG. It is block explanatory drawing which shows the outline | summary of the control part of the apparatus. It is typical explanatory drawing with which it uses for description of 1st Embodiment of this invention. It is a flowchart with which it uses for description of an effect | action of the embodiment. It is a typical explanatory view similarly used for description of the opening detection operation of the negative pressure detection lever. It is typical explanatory drawing with which it uses for description of 2nd Embodiment of this invention. It is a flowchart with which it uses for description of an effect | action of the embodiment. It is typical explanatory drawing with which it uses for description of 3rd Embodiment of this invention. It is a flowchart with which it uses for action description of the embodiment. It is typical explanatory drawing with which it uses for description of 4th Embodiment of this invention. It is a flowchart with which it uses for description of an effect | action of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Paper feed tray 3 ... Paper discharge tray 4 ... Cartridge loading part 10k, 10c, 10m, 10y ... Ink cartridge 33 ... Carriage 34 ... Recording head 35 ... Sub tank 36 ... Ink supply tube 51 ... Conveyor belt 30 ... Control unit 100 ... Ink storage unit 102 ... Film-like member 103 ... Elastic member 106 ... Negative pressure detection lever 312 ... Full tank detection sensor

Claims (13)

  A sub-tank for supplying the recording liquid to a recording head that discharges recording liquid droplets from a nozzle, replenishing and supplying the recording liquid from a main tank on the apparatus main body side, and a negative pressure state in the sub-tank An image forming apparatus comprising: means for performing a negative pressure recovery operation for returning the negative pressure to a normal state when an abnormality in the negative pressure in the sub tank is detected.   2. The image forming apparatus according to claim 1, wherein the negative pressure recovery operation includes an operation of capping the recording head and sucking a recording liquid from a nozzle.   3. The image forming apparatus according to claim 2, wherein an operation of capping the recording head and sucking the recording liquid from the nozzle to recover the negative pressure only when a recording liquid causing a negative pressure drop flows into the sub tank. An image forming apparatus.   4. The image forming apparatus according to claim 2, wherein the recording liquid according to an amount of the recording liquid that causes a negative pressure drop flowing into the sub tank in the operation of capping the recording head and sucking the recording liquid from the nozzle. An image forming apparatus.   5. The image forming apparatus according to claim 2, wherein the negative pressure recovery operation includes an operation of releasing the inside of the sub tank to the atmosphere to regenerate negative pressure.   2. The image forming apparatus according to claim 1, wherein the negative pressure recovery operation includes an operation of sucking air in the sub tank.   7. The image forming apparatus according to claim 6, wherein an operation of sucking air in the sub tank and recovering the negative pressure is performed only when air flows into the sub tank.   8. The image forming apparatus according to claim 6, wherein in the operation of sucking air in the sub tank, air corresponding to the amount of air flowing into the sub tank is sucked.   9. The image forming apparatus according to claim 1, further comprising means for detecting an inflow of recording liquid that causes a drop in air or negative pressure into the sub tank.   10. The image forming apparatus according to claim 9, wherein the means for detecting the inflow of air or recording liquid is a lever that is displaced according to the pressure in the sub tank.   11. The image forming apparatus according to claim 9 or 10, wherein an operation of detecting an inflow of recording liquid that causes a decrease in air or negative pressure to the sub tank is performed when an operation of replenishing and supplying the recording liquid to the sub tank is performed. An image forming apparatus.   12. The image forming apparatus according to claim 1, wherein the operation of recovering the negative pressure is performed only for the recording head in which the abnormality of the negative pressure is detected when performing the maintenance recovery operation for the plurality of recording heads. An image forming apparatus. A sub-tank for supplying the recording liquid to a recording head that discharges recording liquid droplets from a nozzle, replenishing and supplying the recording liquid from a main tank on the apparatus main body side, and a negative pressure state in the sub-tank And a negative pressure maintaining control method for returning the negative pressure to a normal state when an abnormality in the negative pressure in the sub tank is detected. .

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