JP5906699B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to ink supply to a recording head in an inkjet image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, and a multifunction machine of these, for example, an apparatus including a recording head (hereinafter also referred to as a head) constituted by a liquid discharge head is used, and a recording medium (hereinafter also referred to as paper). However, the material is not limited, and the printing medium, the recording medium, the recording paper, the transfer material, and the recording paper are also used synonymously), while the ink (recording liquid) as a liquid is adhered to the paper 2. Description of the Related Art A so-called inkjet image forming apparatus that performs image formation (recording, printing, printing, and printing are also used synonymously) is known.

  As such an ink jet image forming apparatus, a line engine type image forming apparatus in which a plurality of heads are arranged in the main scanning direction is known. In the line engine type image forming apparatus, each head is a head. A configuration that can be replaced every time is known.

  Ink supply means (ink supply system) in such an ink jet type image forming apparatus communicates with heads 1a to 1e that eject ink 10, for example, as shown in FIG. There is known an ink supply system in which a plurality of head tanks a1 to e1 that store ink 10 to be supplied are connected in series.

  Each of the head tanks a <b> 1 to e <b> 1 has a filter for filtering the ink 10 stored in the upstream portion, and is connected to the adjacent head tank on the upstream side of the filter by the supply flow path 22. The most downstream head tank e1 connected in series is connected to the sub tank 2a by a bypass supply flow path 25. Also known is a waste liquid flow path 30 that branches from the bypass supply flow path 25 and discharges the ink 10 to a waste liquid tank (not shown), and a valve 51 that controls the flow of the ink 10 in the waste liquid flow path 30. It has been.

  Here, when filling the ink when the head is initially filled or when the head is replaced during maintenance work, it is important to reliably fill all the head tanks with ink. 2. Description of the Related Art Conventionally, in an image forming apparatus having an ink supply system as shown in FIG. 2, ink filling at the time of initial ink filling or when a recording head is replaced for maintenance work is supplied over a predetermined time. By supplying ink to the flow path, ink filling control to each of the head tanks a1 to e1 is performed (hereinafter, this filling control is also referred to as a sequence).

  Regarding the ink filling, for example, in Patent Document 1, for the purpose of surely filling all recording heads with ink, the ink level stored in the upper tank is detected by a liquid level sensor, and the pump liquid is supplied. An ink filling method is disclosed in which ink is filled into the ink flow path by controlling the operation and the opening / closing operation of the air release valve.

  Further, for example, in Patent Document 2, even if the liquid level is not lowered and the detection mechanism erroneously detects that there is a recording liquid such as ink, the recording liquid can be fed to an appropriate level, which is unnecessary. An image forming apparatus that prevents unnecessary consumption of a recording liquid by suppressing a negative pressure forming operation is disclosed.

  However, the ink supply time in the above-described sequence is set to be long because it is necessary to consider filling variation due to individual differences between the head tank and the head. For this reason, a head or the like that is quickly filled with ink has a problem that unnecessary ink (hereinafter, also referred to as waste liquid) is discharged, and the filling time is unnecessarily prolonged. That is, there has been a problem that it is not possible to perform appropriate ink filling according to individual differences of the heads.

  In the techniques described in Patent Documents 1 and 2, since the detecting means is provided at a position corresponding to the main cartridge 3a and the sub tank 2a shown in FIG. 2, the optimum ink is selected according to the individual difference between the head tank and the head. The filling control could not be performed.

  Therefore, the present invention provides a detection means for detecting the completion of ink filling in the head tank on the most downstream side of the head tanks connected in series, and in the filling when the head is replaced at the initial filling or maintenance work etc. An object of the present invention is to provide an image forming apparatus capable of suppressing unnecessary ink discharge and shortening the filling time.

In order to achieve this object, an image forming apparatus according to the present invention includes a recording head for discharging a recording liquid, and a head tank that communicates with the recording head and stores the recording liquid supplied to the recording head. In an image forming apparatus that includes a plurality and forms an image by discharging a recording liquid from a recording head onto a recording medium, the plurality of head tanks are connected in series via an inter-head tank supply channel that connects the head tanks. The most upstream head tank of the plurality of head tanks and the ink tank for supplying the recording liquid to the plurality of head tanks are connected via the most upstream head tank supply channel, and the most downstream of the plurality of head tanks. a head tank, a flow path switching means is connected via a downstream head tank supply passage, and the passage switching means, the ink tank, through the bypass supply channel Is continued, the flow path shifting unit, the most upstream head tank supply passage, the head tank between the supply passage, and a downstream head tank supply channel comprising a supply channel, and the bypass supply channel, the switching of has a recording liquid supply means capable, among the plurality of the head tank, it is the ash comprises a detecting means for detecting the completion of the feeds the recording liquid to the downstream-most of the head tank to the most downstream head tank.

  According to the present invention, it is possible to suppress the discharge of unnecessary ink and improve the filling efficiency when filling the recording head and the head tank with ink.

1 is a schematic configuration diagram illustrating an overall configuration of an inkjet recording apparatus that is an embodiment of an image forming apparatus. FIG. 3 is a schematic diagram illustrating a main configuration of an ink supply system in an image forming apparatus according to a reference embodiment. FIG. 3 is a schematic diagram showing how ink is filled into a bypass supply channel in the ink supply system shown in FIG. 2. FIG. 3 is a schematic diagram illustrating a state in which filling of a flow path of the ink supply system illustrated in FIG. 2 is completed. It is the schematic which shows the internal structure of a head tank, (A) Side view, (B) Front view. 6 is a control flowchart at the time of initial ink filling in the image forming apparatus according to the reference embodiment. FIG. 2 is a schematic diagram illustrating a main configuration of an ink supply system in the image forming apparatus according to the first embodiment. FIG. 8 is a schematic diagram in which a liquid level detection sensor detects a liquid level in the ink supply system shown in FIG. 7. FIG. 8 is a schematic diagram illustrating a state in which filling of the flow path of the ink supply system illustrated in FIG. 7 is completed. 3 is a control flowchart at the time of initial ink filling in the image forming apparatus according to the first embodiment. FIG. 6 is a schematic diagram illustrating a main configuration of an ink supply system in an image forming apparatus according to a second embodiment. FIG. 12 is a schematic diagram illustrating a state in which the liquid level detection sensor is moved to the replaced head in the ink supply system illustrated in FIG. 11. It is a schematic diagram which shows a mode that ink is filled into the flow path of the ink supply system shown in FIG. FIG. 12 is a schematic diagram illustrating a state where the ink supply system illustrated in FIG. 11 has been filled into a flow path. 10 is a control flowchart at the time of initial ink filling in the image forming apparatus according to the second embodiment.

  Hereinafter, the configuration according to the present invention will be described in detail based on embodiments shown in the drawings.

(Configuration of image forming apparatus)
FIG. 1 is a schematic configuration diagram showing an overall configuration of an ink jet recording apparatus which is an embodiment of an image forming apparatus. The image forming apparatus shown in FIG. 1 is a so-called line engine type image forming apparatus in which a plurality of recording heads 1 are arranged in the main scanning direction. First, an image forming operation by the image forming apparatus will be described.

  First, the paper 8 sent from the paper supply unit 6 is conveyed below the recording head 1 by the conveyance unit 5. As the transport unit 5, for example, a system in which the back surface of the paper 8 is sucked and transported to the transport belt 11 that has been punched by the air suction fan 13 can be adopted. Further, after passing through the transport unit 5, the paper 8 passes over the transport guide plate 9 and is stacked on the paper discharge tray 7.

  As a method for supplying ink to the recording head 1, the ink set in the ink cartridge unit 3 (each main cartridge 3a) is once sent to the sub tank unit 2 (each sub tank 2a) and then supplied to the recording head 1. It is.

  The sub-tank 2a has a component structure in which a spring is inserted therein, a flexible film is welded to one surface of the sub-tank and the internal spring is pressed down, and a negative pressure is formed on the recording head 1 by the return force of the spring. It has become a natural supply system.

  In the cleaning method of the recording head 1, first, the recording head unit 12 is retracted upward, and the cleaning unit 4 is slid into the space formed between the transport unit 5 and the recording head unit 12.

  Next, the recording head unit 12 is lowered and placed on the cleaning unit 4. From this state, the recording head 1 is suctioned with ink in the recording head 1 by a pump suction unit (not shown), and a cleaning operation is executed.

  After the cleaning is completed, the recording head unit 12 is again withdrawn to the upper part, the cleaning unit 4 is returned to the original position, the recording head unit 12 is lowered to the position positioned on the sheet conveying surface of the conveying unit 5, and printing is possible again. It is a state.

(Reference embodiment)
First, prior to description of ink filling control by the image forming apparatus according to the present embodiment, conventional ink filling control (reference embodiment) as a premise will be described.

  FIG. 2 is a schematic diagram illustrating a main configuration of an ink supply system in the image forming apparatus. The ink supply system includes a main cartridge 3a, a sub tank 2a, a head tank a1, b1, c1, d1, e1, heads 1a, 1b, 1c, 1d, and 1e, supply channels 20, 20a, 20b, and the like for each color ink 10. 22, a bypass supply flow path 25, a coupling 50, a three-way valve 51, and the like. In addition, switching control of the three-way valve 51 is performed by a control unit (control means) (not shown).

  The ink supply flow path will be described with reference to FIG. First, the main cartridge 3a and the sub tank 2a are connected by a flow path 20, and the sub tank 2a and the head tank a1 on the ink upstream side are connected by flow paths 20a and 20b. Further, hereinafter, adjacent head tanks are connected in series through the supply flow path 22 up to the head tank e1.

  The most downstream head tank e1 and the sub tank 2a are connected by a bypass supply passage 25 (25a, 25b) via a passage 31 and a three-way valve 51. Here, since the pressure loss of the ink supply increases as going to the head tank e1 on the downstream side, the bypass supply flow path 25 has a function as an auxiliary for the ink supply.

  A coupling 50 is attached in the middle of the supply flow path connecting the head tanks. Even when the ink 10 is filled, the coupling 50 can be disconnected. When head replacement or the like is necessary, the coupling 50 attached to the flow path between the heads is disconnected to remove only the target head. It is exchangeable. A coupling 50 is also attached to the bypass supply channel 25 in the middle of the channel.

  The ink 10 is sent from the ink cartridge 3a to the sub tank 2a, sent from the sub tank 2a to the upstream head tank a1, and supplied in the order of the downstream head tanks b1, c1, d1, and e1.

  Further, the flow path 31 passes through, and the waste liquid flow path 30 passes through the three-way valve 51 and the ink 10 is discharged to a waste liquid tank (not shown).

  During normal ink supply operation, the amount of ink in the sub tank 2a is amplified by the sensor filler 60 by the swelling of the film surface of the sub tank 2a, and the amplitude of the sensor filler 60 is detected by the ink empty detection sensor 62 and the ink full detection sensor 61. And controlled to an appropriate amount. For example, when the ink empty detection sensor 62 detects, the ink supply valve 21 is opened and the ink 10 is supplied from the ink cartridge 3a. When the ink full detection sensor 61 detects, the ink supply valve 21 is closed and the ink supply is stopped. .

  FIG. 3 is a schematic diagram illustrating how the bypass supply flow path is filled with ink. As described above, after the waste liquid flow path 30 has passed, the three-way valve 51 changes the flow path and opens the bypass flow path 25 and the waste liquid flow path 30.

  Further, the ink 10 is passed through the bypass passage 25, the waste fluid passage 30 is passed through the three-way valve 51, and the ink 10 is discharged to the waste fluid tank.

  FIG. 4 is a schematic diagram showing a state where the ink supply system has been filled into the flow path. After passing through the liquid for a predetermined time, the three-way valve 51 changes the flow path to change the flow path 31 and the bypass supply flow path. 25 is opened. With the above control, the supply flow path is filled with the ink 10.

  5A and 5B are schematic views showing the internal configuration of the head tank a1, FIG. 5A is a side view, and FIG. 5B is a front view. The head tanks b1, c1, d1, e1 are similarly configured. The head tank a1 includes a supply port 100, a discharge port 101, a filter 104, a film 103, liquid chambers 105 and 106, and the like.

  As shown in FIG. 5A, the head tank a1 is mainly divided into left and right liquid chambers 105 and 106, and a filter 104 is disposed between the right liquid chamber 105 and the left liquid chamber 106. Has been. Here, the right liquid chamber 105 is upstream of the ink flow filter, and the left liquid chamber 106 is downstream of the ink flow filter. When the ink moves from the upstream liquid chamber 105 to the downstream liquid chamber 106. Will pass through the filter 104. The ink moved to the liquid chamber 106 on the downstream side of the filter is sent to the head 1a.

  Further, the ink that has entered the liquid chamber 105 on the upstream side of the filter of the head tank a1 from the supply port 100 passes through the filter 104 as described above, and is sent to the discharge port 101, and on the discharge port 101 side. The ink to be sent is sent to adjacent downstream heads (in this case, the head tank b1).

  In this ink supply system, since the ink flow is communicated with the liquid chamber 105 on the upstream side of the filter 104 in the head tank, it is possible to supply ink to the next head while suppressing the flow path resistance as much as possible.

  Further, a flexible film 103 is welded to one surface of the liquid chamber 105 on the upstream side of the head tank a1, and pressure fluctuations generated by ON / OFF of the ink flow can be absorbed (absorbing pressure fluctuations). Damper function).

  Next, with reference to a flowchart shown in FIG. 6, the control at the time of initial ink filling in the image forming apparatus according to the reference embodiment will be described.

  First, when a command to execute ink filling is issued from the control unit of the image forming apparatus (S101), it is detected by a detecting means (not shown) whether or not the ink 10 is present in the main cartridge 3a (S102). Here, when the ink 10 is not in the main cartridge 3a (S102: N), the fact is notified to the operation panel of the image forming apparatus (S103).

  On the other hand, when the ink 10 is present in the main cartridge 3a (S102: Y), the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the flow path 31 (S104). Next, the ink supply valve 21 is opened to open the flow paths 20, 20a, 20b, 22, 31 and the ink cartridge 3a (S105).

  Next, after supplying the ink 10 from the ink cartridge 3a for a predetermined time (sequence), the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the bypass supply flow path 25. (S106). Also in this case, after supplying the ink 10 for a predetermined time set in advance (sequence), the ink supply valve 21 is closed (S107). Thereafter, the flow path of the three-way valve 51 is changed to open the flow path 31 and the bypass supply flow path 25 (S108).

  Finally, the nozzle surface (not shown) is sucked by the head 1 with a head suction cap (not shown), and the common liquid chamber / individual liquid chamber in the head 1 is filled with ink 10 (S109). Further, the head suction cap is retracted (S110), and the nozzle surface is cleaned by wiping (S111). After the above control, the head 1 is capped and put into a standby state (S112).

  In the ink initial filling control according to the reference embodiment described above, the ink 10 is supplied for a predetermined time (S106, 107) (sequence), and therefore the filling efficiency is low, that is, as described above. In addition, since it is necessary to take into account filling variations due to individual differences between head tanks and heads, ink was uniformly filled in a long filling time. There was a problem that ink was discharged and the filling time was unnecessarily prolonged.

(First embodiment)
Therefore, the image forming apparatus according to the present embodiment communicates with the recording head (heads 1a, 1b, 1c, 1d, and 1e) for discharging the recording liquid (ink 10) and the recording head. In an image forming apparatus including a plurality of head tanks (head tanks a1, b1, c1, d1, e1) for storing recording liquid to be supplied and performing image formation by discharging recording liquid from a recording head onto a recording medium. The plurality of head tanks are connected in series via a supply channel (channel 22), and supply the recording liquid to the most upstream head tank (head tank 1a) among the plurality of head tanks and the plurality of head tanks. An ink tank (sub tank 2a) is connected via supply channels (channels 20a and 20b), and the most downstream head tank (head tank 1e) of the plurality of head tanks; The path switching means (three-way valve 51) is connected via a supply flow path (flow path 31), and the flow path switching means and the ink tank are connected via a bypass supply flow path (bypass supply flow path 25). And a recording liquid supply means capable of switching between the supply flow path and the bypass supply flow path by the flow path switching means, and among the plurality of head tanks, the most downstream head tank is connected to the most downstream head tank. It is provided with detection means (liquid level detection means, liquid level detection sensor 71, electrode pin 70) for detecting the completion of supply of the recording liquid.

  7 and 8 are schematic views showing the main configuration of the ink supply system in the present embodiment. Note that a description of the same points as in the reference embodiment is omitted. Further, switching control of the three-way valve 51, detection control by the liquid level detection means, and the like are performed by a control unit (control means) (not shown).

  As shown in FIG. 7, the ink supply system in the present embodiment includes detection means for detecting completion of filling in the most downstream head tank e1, specifically, a liquid level detection sensor 71 and an electrode pin 70 ( Liquid level detection means). Here, as the liquid level detection means, for example, an electrode pin method can be used. The electrode pin method is known as a method of detecting the liquid level by energizing the electrode pins 70 and conducting electricity between the electrode pins 70 via the liquid, and detailed description thereof is omitted. Further, the detection means is not limited to the electrode pin method, and other methods may be used.

  In the image forming apparatus according to the present embodiment, when the most downstream head tank e1 is filled with ink 10 (FIG. 8), this is detected by the liquid level detection sensor 71, and after detection, the flow path 31 is filled. The ink 10 is supplied for a predetermined time which is sufficient.

  That is, unlike the reference embodiment, the ink filling control is performed only for the time until the detection by the liquid level sensor 71 and the time sufficient for filling the flow path 31 thereafter, so that it corresponds to the individual difference of the head. An optimum amount of ink can be supplied, and it is possible to avoid the use of ink unnecessary for the initial filling of ink.

  The subsequent ink filling will be described with reference to FIG. As described above, after supplying the ink 10 for a predetermined time sufficient to fill the flow path 31, the three-way valve 51 changes the flow path to open the bypass supply flow path 25 and the waste liquid flow path 30. Next, the ink 10 is supplied for a predetermined time that is sufficient to fill the bypass supply flow path 25, and finally, the flow is completed by opening the flow path 31 and the bypass supply flow path 25.

  That is, unlike the reference embodiment, the ink flow (sequence) in which ink is filled for a predetermined time that is set in advance can be the flow path 31 and the bypass supply flow path 25 alone. Regardless, the filling efficiency can be improved.

  Next, ink supply control in the image forming apparatus according to the present embodiment will be described with reference to a flowchart shown in FIG. First, when a command to execute ink filling is issued from the control unit of the image forming apparatus (S201), it is detected by the detecting means whether or not the ink 10 is present in the main cartridge 3a (S202). If the ink 10 is not present in the main cartridge 3a (S202: N), this is notified to the operation panel of the image forming apparatus (S203).

  On the other hand, when the ink 10 is present in the main cartridge 3a (S202: Y), it is confirmed whether or not the liquid level detection sensor 71 is OFF. (S204).

  When the liquid level detection sensor 71 is ON (S204: N), an abnormality is notified to the operation panel or the like (S205). On the other hand, when the liquid level detection sensor 71 is OFF (S204: Y), the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the flow path 31 (S206).

  Next, the ink supply valve 21 is opened to fill the ink 10 (S207), and it is detected whether or not the liquid level detection sensor 71 is ON (S208). When the liquid level detection sensor 71 is OFF (S208: N), the ink supply valve 21 is continuously opened to supply the ink 10 (S209).

  On the other hand, when the liquid level detection sensor 71 is turned on (S208: Y), the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the bypass supply flow path 25 (S210). Further, after the ink 10 is passed through the bypass supply channel 25 for a predetermined time, the ink supply valve 21 is stopped (S211).

  Next, after the ink supply valve 21 is stopped, the flow path of the three-way valve 51 is changed to open the flow path 31 and the bypass supply flow path 25 (S212).

  Finally, the heads 1a to 1e are sucked by the head suction cap for a predetermined time, and the head 10 is filled with ink 10 (S213). After sucking for a predetermined time, the head suction cap is retracted (S214), and the head nozzle surface is moved. Cleaning is performed by wiping (S215). After the above control, the heads 1a to 1e are capped to enter a standby state (S216).

  As described above, conventionally, as in the reference embodiment, with respect to the initial filling of ink, long supply channels (channels 20a and 20b, channel 22, ink tanks a1 to e1, and channel 31) are set in advance. In addition, since the control (sequence) for filling the ink for a predetermined time was performed, as a result, a lot of ink was made into waste liquid due to individual differences of the heads. This is because the predetermined time is set long in consideration of filling variation due to individual differences in the heads.

  In contrast, in this embodiment, the liquid level detection sensor 71 is provided in the most downstream head tank e1 connected in series, so that the ink is filled up to the most downstream head tank regardless of individual head differences. The amount of ink necessary for filling can be reliably detected to eliminate waste liquid, shorten the ink filling time, improve the filling efficiency, and reliably fill the head tank. it can. Further, since the supply flow path to be filled in a sequence is only the flow path 31 and the bypass supply flow path 25 as in the prior art, ink can be filled with a minimum amount of waste liquid.

(Second Embodiment)
FIG. 11 is a configuration diagram of an ink supply system of the image forming apparatus according to the second embodiment. In the second embodiment, a case will be described in which one of the heads is replaced with an ink-unfilled head (eg, the head 1c and the head tank c1) by maintenance work or the like.

  FIG. 11 shows a connection state of the supply flow path after the head 1c is replaced by maintenance. The head 1c has an electrode pin 70b in the head tank c1. By disconnecting / connecting the coupling 50, the flow path 26a on the upstream side of the head 1c and the bypass supply flow path 25a in the flow path 22 are connected, and the flow path 26b on the downstream side of the head 1c is connected to the bypass supply flow path. 25b.

  FIG. 12 is an explanatory diagram showing a state in which the liquid level detection sensor 71 provided in the most downstream head tank e1 is moved to the head 1c that has undergone maintenance replacement. The movement of the liquid level detection sensor 71 is to remove the liquid level detection sensor 71 provided in the most downstream head tank e1 and connect this liquid level detection sensor 71 to the electrode pin 70b of the head tank c1 that has undergone maintenance and replacement. Good. Note that it is not always necessary to move the liquid level detection sensor 71 of the head tank e1, and it is also possible to prepare a head tank c1 for replacing another liquid level detection sensor 71 in advance and change only the wiring. Of course.

  FIG. 13 is a schematic diagram illustrating a state in which ink is filled after the head tank replacement described with reference to FIG. The ink 10 passes through the bypass supply channel 25a and is filled into the head tank c1, and when the filling is continued, the liquid level detection sensor 71 detects that the ink 10 is full.

  After the full tank detection of the head tank c1, as in the first embodiment, the ink 10 is supplied for a predetermined time in an amount to fill the bypass supply flow path 25b, and the supply of the ink 10 is stopped after the predetermined time. The

  After that, as shown in FIG. 14, the bypass 50 connected to the bypass supply flow path 25a and the flow path 26a, and the bypass supply flow path 25b and the flow path 26b are disconnected, and the separated bypass supply flow path 25a and the bypass supply are disconnected. The flow path 25b is connected, and the connection portion of the head tank c1 is connected to the flow path 22 of the adjacent head tank.

  As described above, by using the liquid level detection means for the head tank to be replaced at the time of maintenance replacement, it is not necessary to fill the entire supply flow path connected in series in a sequence as in the prior art. Since only the path 25a and the flow path 26b need to be filled in a sequence, the ink filling efficiency can be improved and the discharge of the ink 10 can be reduced. In addition, the common liquid level detection sensor 71 can be shared to reduce the cost.

  Next, ink supply control in the image forming apparatus according to the second embodiment will be described with reference to a flowchart shown in FIG.

  In the present embodiment, first, the liquid level detection sensor 71 is moved and connected to the electrode pin 70b of the head tank c1 for which maintenance has been replaced (S301).

  Next, when a command to execute ink filling is issued from the control unit of the image forming apparatus (S302), the detection unit detects whether or not the ink 10 is present in the main cartridge 3a (S303). If the ink 10 is not present in the main cartridge 3a (S303: N), this is notified to the operation panel of the image forming apparatus (S304).

  On the other hand, when the ink 10 is present in the main cartridge 3a (S303: Y), it is confirmed whether or not the liquid level detection sensor 71 is OFF. (S305).

  When the liquid level detection sensor 71 is ON (S305: N), an abnormality is notified to the operation panel or the like (S306). On the other hand, when the liquid level detection sensor 71 is OFF (S305: Y), the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the bypass supply flow path 25b (S307).

  Next, the ink supply valve 21 is opened to fill the ink 10 (S308), and it is detected whether or not the liquid level detection sensor 71 is ON (S309). When the liquid level detection sensor 71 is OFF (S309: N), the ink supply valve 21 is continuously opened to supply the ink 10 (S310).

  On the other hand, when the liquid level detection sensor 71 is turned on (S309: Y), the ink supply valve 21 is closed and the supply of the ink 10 is stopped (S311).

  Next, the flow path of the three-way valve 51 is changed to open the waste liquid flow path 30 and the bypass supply flow path 25b (S312), and the completion of ink filling is notified (S313).

  After the notification of ink filling completion, the bypass supply channels 25a and 25b and the channel adjacent to the head tank are connected (S314), and a command to execute filling of the head is issued from the control unit (S315).

  Finally, the heads 1a to 1e are sucked by the head suction cap for a predetermined time, and the head 10 is filled with ink 10 (S316). After sucking for a predetermined time, the head suction cap is retracted (S317), and the head nozzle surface is moved. Cleaning is performed by wiping (S318). After the above control, the heads 1a to 1e are capped to enter a standby state (S319).

  According to the second embodiment described above, since the filling in the sequence is only the bypass supply flow path 25b and the flow path 26b, the ink filling efficiency at the time of head replacement can be improved and the waste liquid can be reduced.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

a1, b1, c1, d1, e1 Head tank 1 (1a, 1b, 1c, 1d, 1e) Recording head (head)
2 Sub tank unit 2a Sub tank 3 Ink cartridge unit 3a Main cartridge 4 Cleaning unit 5 Transport unit 6 Paper feed unit 7 Paper discharge unit 8 Paper 9 Transport guide plate 10 Ink 11 Transport belt 12 Recording head unit 13 Air adsorption fans 20, 20a, 20b , 22 Flow path 21 Ink supply valve 25 (25a, 25b) Bypass supply flow path 26a Upstream flow path 26b Downstream flow path 30 Waste liquid flow path 31 Flow path 50 Coupling 51 Three-way valve 60 Sensor filler 62 Ink empty detection Sensor 61 Ink full detection sensor 70, 70b Electrode pin 71 Liquid level detection sensor 100 Supply port 101 Discharge port 103 Film 104 Filter 105 Liquid chamber (upstream side)
106 Liquid chamber (downstream)

JP 2010-105169 A JP 2011-104932 A

Claims (5)

A recording head for discharging the recording liquid;
A plurality of head tanks that communicate with the recording head and store recording liquid supplied to the recording head;
In an image forming apparatus that forms an image by discharging a recording liquid from the recording head onto a recording medium,
The plurality of head tanks are connected in series via a supply path between head tanks connecting the head tanks ,
The most upstream head tank of the plurality of head tanks and an ink tank that supplies recording liquid to the plurality of head tanks are connected via the most upstream head tank supply flow path,
The most downstream head tank of the plurality of head tanks and the flow path switching means are connected via the most downstream head tank supply flow path,
The flow path switching means and the ink tank are connected via a bypass supply flow path,
The flow path switching means includes: a supply flow path including the most upstream head tank supply flow path, the inter-head tank supply flow path, and the most downstream head tank supply flow path; and the bypass supply flow path . It has a recording liquid supply means that can be switched,
An image forming apparatus comprising: a detecting unit configured to detect completion of supply of a recording liquid to the most downstream head tank among the plurality of head tanks. The flow path switching means can supply the recording liquid to the supply flow path including the most upstream head tank supply flow path, the inter-head tank supply flow path, and the most downstream head tank supply flow path. 2. The image forming apparatus according to claim 1, further comprising a control unit configured to supply the recording liquid until the detection unit detects the completion of the supply in the most downstream head tank. The control means, after detecting the supply completion in the most downstream head tank by the detection means, the most downstream head tank supply flow path connecting the most downstream head tank and the flow path switching means, The image forming apparatus according to claim 2, wherein the recording liquid is supplied to the bypass supply channel for a predetermined time. A detection means for detecting the completion of the supply of the recording liquid to the replaced head tank is provided in the head tank that is replaced in a state where the recording liquid is not filled,
4. The image forming apparatus according to claim 1, further comprising a control unit that supplies the recording liquid until the detection unit detects the completion of the supply in the replaced head tank.   The image forming apparatus according to claim 1, wherein the detection unit includes a liquid level detection sensor and an electrode pin.