Inkjet recording device

Abstract

To provide a small-sized inkjet recording device, which can stably supply ink to a recording head and has a high degree of freedom in arranging an ink tank.SOLUTION: The inkjet recording device is configured to comprise: a recording head comprising a nozzle row constituted of a plurality of nozzles and negative pressure generating means that applies negative pressure to the nozzle row; a storage part that stores ink; and an ink tank comprising an atmosphere communication port through which the storage part communicates with an atmosphere and an inlet port through which ink is poured into the storage part. The recording head is connected to the ink tank through a tube so that ink is supplied from the ink tank to the recording head, where the ink tank and the recording head are installed as follows: a highest position of liquid level of ink in the ink tank in a vertical direction is higher than a position of the nozzle row of the recording head, and an absolute value of hydraulic head pressure generated by a difference between the highest position and the position of the nozzle row is equal to an absolute value of negative pressure generated by the negative pressure generating means or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an inkjet printing apparatus that supplies ink contained in an ink tank to a print head and ejects the ink from the print head to print. [Background technology]

[0002] Conventionally, there have been known recording devices that have a recording head mounted on a movable carriage and an ink tank connected to the carriage by a tube, and that allow a user to inject ink into the ink tank. Among such recording devices, there is known a device that provides a stable supply of ink by arranging an air intake passage at a position lower than the nozzles of the recording head and allowing the ink level in the ink tank to be accommodated at a position higher than the nozzles of the recording head, thereby allowing a high degree of freedom in the arrangement of the ink tank.

[0003] In the recording device disclosed in Patent Document 1, the ink inlet is covered with a part of a lid, thereby preventing the cap of the ink tank at the inlet from coming off and impairing the stable supply of ink to the recording head. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 112344 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above conventional configuration, even if the ink inlet is covered with a lid, if the sealing is incomplete, for example, if the tank cap is not attached due to a user's operational error, the following problems may occur: That is, if the ink level in the ink tank is higher than the nozzles of the print head, the nozzles of the print head are pressurized, compromising the stable supply of ink.

[0006] Furthermore, there have been known recording devices equipped with ink tanks in which the ink level is lower than the nozzles of the recording head. However, this reduces the degree of freedom in the placement of the ink tank, which results in a problem of the device becoming taller and larger in size.

[0007] SUMMARY OF THE PRESENT EMBODIMENT The present invention has been made in consideration of the above-mentioned conventional examples, and has an object to provide a small-sized ink jet recording apparatus which stably supplies ink to a recording head and allows a high degree of freedom in the arrangement of ink tanks. [Means for solving the problem]

[0008] In order to achieve the above object, the ink jet recording apparatus of the present invention has the following configuration.

[0009] That is, the recording head includes a nozzle row consisting of a plurality of nozzles that eject ink, and negative pressure generating means for applying negative pressure to the nozzle row, an ink tank including a container for storing ink, an atmosphere communication port that connects the container with the atmosphere, and an injection port for injecting ink into the container, and a tube that connects the recording head and the ink tank and supplies ink from the ink tank to the recording head, wherein during a recording operation in which ink is ejected from the nozzle row to record an image, the recording head and the ink tank are connected via the tube, and the highest position of the ink level in the ink tank in the vertical direction is higher than the position of the nozzle row of the recording head, and the absolute value of the head pressure generated by the difference between the highest position of the ink level in the ink tank and the position of the nozzle row of the recording head is equal to or less than the absolute value of the negative pressure generated by the negative pressure generating means. The negative pressure generating means includes a porous body or a spring bag including a spring. It is characterized by:

[0010] The inkjet recording apparatus may also have the following features.

[0011] That is, a nozzle row consisting of a plurality of nozzles that eject ink 、 a negative pressure generating means for applying a negative pressure to the nozzle row; 、a recording head including the ink tank, the ink tank including a storage section for storing ink, an air communication port for communicating the storage section with the atmosphere, and an injection port for injecting ink into the storage section; and a tube for connecting the recording head and the ink tank and supplying ink from the ink tank to the recording head. picture, The ink tank has a buffer chamber that is provided vertically above the storage section between the storage section and the atmosphere vent, and is capable of storing ink that has flowed out from the storage section, and is characterized in that the highest position of the ink liquid level in the buffer chamber in the vertical direction is higher than the position of the nozzle row of the recording head, and the absolute value of the head pressure generated by the difference between the highest position of the ink liquid level in the buffer chamber and the position of the nozzle row of the recording head is equal to or less than the absolute value of the negative pressure generated by the negative pressure generating means. Effect of the Invention

[0012] According to the present invention, it is possible to prevent pressure from being applied to the nozzles of the print head even if the ink tank is incompletely sealed, thereby making it possible to stably supply ink to the print head.

[0013] In addition, there is less restriction on the height between the ink surface and the nozzles of the print head, and the degree of freedom in arranging the ink tanks is increased, which makes it possible to reduce the height of the ink jet printing apparatus and make it more compact.

[0014] Furthermore, even if the ink level rises to a high level due to ink flowing into the space above the ink tank due to a change in the ink tank's position after the ink has been filled, the nozzle rows of the print head are not pressurized, allowing for a stable supply of ink, thereby maintaining high reliability. [Brief description of the drawings]

[0015] [Figure 1] 1 is a partially cutaway perspective view showing the schematic configuration of an inkjet recording apparatus according to a typical embodiment of the present invention; [Diagram 2]FIG. 2 is a block diagram showing a control configuration of the printing apparatus shown in FIG. [Diagram 3] FIG. 2 is a diagram illustrating an ink supply configuration from an ink tank to a print head according to the first embodiment of the present invention. [Figure 4] 4 is a diagram showing a schematic diagram of a state during ink injection in the ink supply configuration shown in FIG. 3. [Diagram 5] 4 is a diagram illustrating a state in which there is no ink in the tubes in the ink supply configuration illustrated in FIG. 3. [Figure 6] FIG. 10 is a diagram illustrating an ink supply configuration from an ink tank to a print head according to a second embodiment of the present invention. [Figure 7] 7 is a diagram showing a schematic diagram of a state during ink injection in the ink supply configuration shown in FIG. 6. [Figure 8] 7 is a diagram illustrating a state in which there is no ink in the tubes in the ink supply configuration illustrated in FIG. 6. [Figure 9] FIG. 10 is a diagram illustrating an ink supply configuration from an ink tank to a print head according to a third embodiment of the present invention. [Figure 10] 10 is a diagram showing a schematic diagram of a state in which an ink tank and a print head are connected to each other by a supply tube in the ink supply configuration shown in FIG. 9. FIG. [Figure 11] 10 is a diagram showing a schematic diagram of a state in which there is no ink in the tube even when the print head and the ink tank are connected in the ink supply configuration shown in FIG. 9. FIG. [Figure 12] FIG. 10 is a diagram illustrating an ink supply configuration from an ink tank to a print head according to a fourth embodiment of the present invention. [Figure 13] 11 is a diagram showing a schematic diagram of another configuration of the negative pressure generating means inside the recording head. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A preferred embodiment of the present invention will be described more specifically and in detail below with reference to the attached drawings. Note that the following embodiment does not limit the invention according to the claims. Although the embodiment describes a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0017] In this specification, "recording" (sometimes called "printing") refers not only to the formation of meaningful information such as characters and figures, but also to the formation of images, patterns, etc. on a recording medium, regardless of whether they are visible to humans or not, or to the processing of the medium.

[0018] In addition, the term "recording medium" refers not only to paper used in general recording devices, but also broadly to anything capable of receiving ink, such as cloth, plastic film, metal plate, glass, ceramics, wood, and leather.

[0019] Furthermore, "ink" (sometimes called "liquid") should be interpreted broadly in the same way as the definition of "recording (print)" above. Therefore, it refers to a liquid that can be applied onto a recording medium to form an image, design, pattern, etc., or to process the recording medium, or to process the ink (for example, to solidify or insolubilize the coloring material in the ink applied to the recording medium).

[0020] Furthermore, unless otherwise specified, the term "nozzle" collectively refers to the ejection port, the liquid path communicating with the ejection port, and the element that generates the energy used to eject ink.

[0021] The term "printhead substrate (head substrate)" used below does not refer to a simple base body made of silicon semiconductor, but to a configuration on which various elements, wiring, etc. are provided.

[0022] Furthermore, "on the substrate" does not simply refer to the top of the element substrate, but also refers to the surface of the element substrate and the inner side of the element substrate near the surface. Furthermore, "built-in" in the present invention does not simply refer to the arrangement of separate elements on the surface of a substrate as separate elements, but refers to the formation and manufacture of each element integrally on an element substrate by a semiconductor circuit manufacturing process or the like.

[0023] FIG. 1 is a perspective view showing the schematic configuration of an inkjet printing apparatus (hereinafter, printing apparatus) according to a typical embodiment of the present invention.

[0024] During recording in the recording device 50 shown in Fig. 1, the recording medium is fed by a feed roller (not shown), sandwiched between a transport roller 1 and a pinch roller 2 driven by the transport roller 1, and transported in the direction of arrow A in the figure while being guided and supported on a platen 3 by the rotation of the transport roller 1. The transport roller 1 is a metal roller processed to form fine irregularities on its surface so that it can generate a large frictional force. The pinch roller 2 is elastically biased against the transport roller 1 by a spring (not shown) or the like. The platen 3 supports the back surface of the recording medium so as to maintain a constant or predetermined distance between the ink ejection surface of the recording head 4 and the surface of the recording medium facing it.

[0025] The recording medium transported onto the platen 3 is then sandwiched between a discharge roller (not shown) and a spur, which is a rotating body that rotates relative to the discharge roller, and is transported. The discharge roller is a rubber roller with a large friction coefficient. The spur is elastically biased against the discharge roller by a spring (not shown) or the like. After image recording, the recording medium is discharged from the platen 3 to the outside of the device by the rotation of the discharge roller.

[0026] The recording head 4 is removably mounted on a carriage 7 that is reciprocated by a carriage motor or the like along guide rails 5 and 6 arranged above and below, in a position that allows it to eject ink toward the recording medium. The direction of movement of the carriage 7 is a direction that intersects with the recording medium transport direction (direction of arrow A) and is also called the main scanning direction. In contrast, the recording medium transport direction is called the sub-scanning direction.

[0027] The recording head 4 uses a method of inkjet recording in which an electrothermal conversion element (heater) that generates thermal energy as the energy used to eject ink is used to cause a change in the state of the ink (film boiling) using that thermal energy. This achieves high density and high definition recording. Note that the method is not limited to this type of thermal energy method, and a method using vibration energy generated by a piezoelectric element may also be used.

[0028] The ink ejection surface of the recording head 4 is provided with a plurality of nozzle rows for ejecting ink of different colors. A plurality of independent ink tanks 8 are attached and fixed to the device body corresponding to the colors of ink ejected from the recording head 4. The ink tanks 8 and the recording head 4 are connected by joints (not shown) through a plurality of supply tubes 10 corresponding to each color of ink, and the color of ink stored in each ink tank 8 can be independently supplied to each nozzle row of the recording head 4 corresponding to each color of ink.

[0029] Furthermore, in a non-printing area, which is an area within the reciprocating movement range of the recording head 4 but outside the passing range when the recording medium P is transported, a recovery unit 11 is disposed so as to face the ink ejection surface of the recording head 4. The recovery unit 11 has a cap for capping the ink ejection surface of the recording head 4, a suction mechanism for forcibly sucking ink from the recording head 4 while the ink ejection surface is capped, a cleaning blade for wiping off dirt from the ink ejection surface, and the like.

[0030] FIG. 2 is a block diagram showing a control configuration of the printing apparatus shown in FIG.

[0031] 2, the recording device 50 is connected to a host computer 390 in which a printer driver 391 is installed, for example, via a USB interface or the like. In response to a print command from a user, the printer driver 391 generates print data from image data such as a document or photo desired by the user, and transmits this to the recording device 50. The print data and the like transmitted from the host computer 390 to the recording device 50 are temporarily stored in a receiving buffer 310.

[0032] The recording device 50 is equipped with a CPU 300 that controls the entire device, a ROM 330 that contains control software, a RAM 320 that is temporarily used when the recording device 50 runs the control software, and an NVRAM 340 that retains information even without power. Print data and other data stored in the receive buffer 310 is transferred to the RAM 320 under the control of the CPU 300 and temporarily stored therein. The CPU 300 accesses the RAM 320, ROM 330, NVRAM 340, etc. to execute various operations such as calculation, control, judgment, and setting.

[0033] Furthermore, the CPU 300 drives the recording head 4 via a head driver 350, controls the operation panel 54 via an operation panel controller 380, and drives various motors 365 via a motor driver 360. The various motors 360 include a carriage motor, a transport motor, and a motor for moving a cap up and down. Furthermore, the CPU 300 controls various sensors 375 via a sensor controller 370.

[0034] Next, in the printing apparatus having the above-mentioned configuration, several embodiments of the configuration for supplying ink from the ink tank to the print head will be described in detail with reference to the drawings. EXAMPLES

[0035] FIG. 3 is a diagram showing a schematic configuration of ink supply from an ink tank to a print head according to the first embodiment of the present invention.

[0036] 3, as also suggested in FIG. 1, ink tanks 8 are provided for each corresponding ink color, and each ink tank is provided with a supply tube 10. An air communication port 28 is provided in the ink tank 8, and the ink tank 8 communicates with an ink containing section (first space) 33 through buffer chambers 29-30 and a communication section 24. An ink inlet 21 is opened at the top of the ink tank 8, and a tank cap 22 is attached to the ink inlet 21. The user can inject ink into the ink containing section 33 by removing the tank cap 22.

[0037] At least a part of the side of the ink tank 8 is a visible surface 25 made of a transparent material, through which the user can visually check the ink level in the ink tank 8. The visible surface 25 is provided with protrusions 26 and 27, which indicate the highest and lowest ink levels at which normal recording can be performed. During recording, ink is continuously supplied from the ink supply unit 23 provided on the bottom of the ink storage unit 33 through the supply tube 10 in an amount equal to the amount of ink discharged from the recording head 4. When ink is consumed during recording and the ink level drops to the position of the protrusion 27, it is necessary to inject ink from the ink inlet 21. By injecting ink in the range from the protrusion 27 to the protrusion 26, the user can perform recording without running out of ink. The determining parts that determine the highest and lowest ink levels are not limited to the protrusions 26 and 27, but can also be replaced by lines or the like drawn on the visible surface 25.

[0038] The buffer chambers (second spaces) 29-30 can contain ink that flows out when the air in the ink storage section 33 expands due to temperature changes or the like when the device main body is turned upside down during transportation, etc. This makes it possible to prevent ink from leaking out of the ink tank through the air communication port 28. When the device is returned to its normal position after transportation, the ink that flowed into the buffer chambers 29-30 returns to the ink storage section 33, enabling normal recording operations.

[0039] In the example of the ink tank 8 shown in FIG. 3, the ink tank 8 is configured to have two buffer chambers, but the number of buffer chambers may be one, or three or more buffer chambers may be provided.

[0040] Fig. 4 is a diagram showing a schematic diagram of a state when ink is injected into the ink supply configuration shown in Fig. 3. In particular, Fig. 4 shows a state in which the tank cap 22 is removed from the ink tank 8.

[0041] As shown in Figures 3 and 4, a porous body 32 is provided inside the recording head 4, and negative pressure due to capillary force is applied to the nozzle row 31. This negative pressure is determined by the compression ratio of the porous body 32 stored inside the recording head 4 and the amount of ink. When the compression ratio is high, the negative pressure becomes large (strong), and when the compression ratio is low, the negative pressure becomes small (weak). On the other hand, when the amount of ink is large, the negative pressure becomes small (weak), and when the amount of ink is large, the negative pressure becomes large (strong).

[0042] In the following explanation, the unit of pressure will be mmAq (millimeter of water column) to easily relate it to the water head height, and the specific gravity of ink will be assumed to be 1.

[0043] The porous body 32 is stored with a compression ratio and ink filling amount such that the generated negative pressure is -50 to -80 mmAq. The protrusion 26, which is an indicator of the highest position of the ink level in the main tank 8, is located at a position higher than the nozzle row 31 by a height H in the vertical direction, so that a positive head pressure of the height H is applied to the nozzle row 31. In this embodiment, H is set to 20 mm. Here, when the negative pressure applied by the porous body 32 and the positive head pressure of the height H of the ink level in the ink tank 8 are added together, the pressure in the nozzle row 31 becomes -30 to -60 mmAq, which is a pressure below 0 (i.e., negative pressure). In other words, the absolute value of the head pressure generated by the height H is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is pressurized and ink leakage from the nozzle row 31 is suppressed.

[0044] Fig. 5 is a schematic diagram showing a state where there is no ink in the tube in the ink supply configuration shown in Fig. 3. Possible cases where the ink runs out in the tube 10 as shown in Fig. 5 are when air gets in through the tube surface after a long period of storage, or when the user forgets to refill the ink. That is, a phenomenon occurs where the ink in the tube 10 is pushed out into the ink tank 8 by the air that gets in through the tube surface. The material used for the tube 10 is a styrene-based thermoplastic elastomer, which is relatively inexpensive and has good gas barrier properties.

[0045] As shown in FIG. 5, when there is no ink in the tube 10, a positive head pressure corresponding to a depth D from the highest ink level in the ink tank 8 to the bottom surface of the ink tank 8 is applied to the nozzle row 31. In this embodiment, the depth D is set to 40 mm. Here, when the negative pressure applied by the porous body 32 and the positive head pressure corresponding to the height D are added together, the pressure in the nozzle row 31 becomes −10 to −40 mmAq, which is a pressure (negative pressure) below 0. That is, the absolute value of the head pressure generated by the depth D is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, even in this case, the nozzle row 31 is pressurized and ink leakage from the nozzle row 31 is suppressed.

[0046] Therefore, according to the embodiment described above, the nozzle row of the print head can be positioned within the range of fluctuation of the ink level in the ink tank, so the height of the printing device itself can be kept low. Furthermore, even if a user makes an operational error such as forgetting to close the tank cap or if the printing device is left unused for a long period of time, the nozzle row will not be pressurized, and a stable supply of ink is possible. This achieves the miniaturization of the printing device and maintains high reliability. EXAMPLES

[0047] Fig. 6 is a diagram showing a schematic configuration of an ink supply from an ink tank to a print head according to a second embodiment of the present invention. In Fig. 6, the same components as those in the first embodiment described with reference to Figs. 3 to 5 are given the same reference numerals, and the description thereof will be omitted.

[0048] 6, a cylindrical ink injection auxiliary member 34 that forms a flow path is attached to the ink tank 8, and communicates between the outside of the ink tank 8 and the ink containing section 33. The ink injection auxiliary member 34 is sealed by a tank cap 40 except when ink is being injected.

[0049] The ink injection assistant member 34 may be formed integrally with the ink tank 8. Although the ink injection assistant member 34 has two inner flow paths in this embodiment, it may have three or more inner flow paths. That is, it is sufficient that at least two flow paths are provided: a flow path through which ink flows from the ink bottle 41, which serves as an ink supply container, toward the ink tank 8, and a flow path through which air flows from the ink tank 8 toward the ink bottle 41.

[0050] FIG. 7 is a diagram showing a schematic state of the ink supply configuration shown in FIG. 6 during ink injection.

[0051] In FIG. 7, (a) shows a state in which the tank cap 40 is removed and ink can be injected. The ink bottle 41 contains ink, and the slit valve 42, which is a thin elastic rubber with a slit, prevents ink from leaking even when the bottle is turned upside down. In contrast, (b) shows a state in which the ink bottle 41 is connected to the ink injection auxiliary member 34. The tip of the ink injection auxiliary member 34 penetrates the slit of the slit valve 42, so that the ink contained in the ink bottle 41 can be injected into the ink storage section 33 of the main tank 8. As shown in FIG. 7(b), the ink injection stops when the liquid level in the ink storage section 33 reaches the lower end of the ink auxiliary member 34, and the injection is completed. In other words, the length of the ink auxiliary member 34 is designed so that the liquid level at the end of the injection is the highest position 26 of the ink liquid level in the ink tank 8. When the ink injection is completed, the user pulls the ink bottle 41 upward and attaches the tank cap 43.

[0052] As shown in FIG. 6, the highest position 26 of the ink level in the ink tank 8 is located at a position higher than the nozzle row 31 by a height H in the vertical direction, so that a positive head pressure of the height H is applied to the nozzle row 31. In this embodiment, H is set to 20 mm. Here, when the negative pressure applied by the porous body 32 and the positive head pressure of the height H are added together, the pressure (negative pressure) applied to the nozzle row 31 is −30 to −60 mmAq, which is a pressure of 0 or less. That is, the absolute value of the head pressure generated by the height H is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is pressurized and ink leakage from the nozzle row 31 is suppressed.

[0053] FIG. 8 is a schematic diagram showing a state in which there is no ink in the tubes in the ink supply configuration shown in FIG.

[0054] In the configuration shown in FIG. 8, a positive head pressure corresponding to a depth D from the highest ink level (highest position 26) in the ink tank 8 to the bottom surface of the ink tank 8 is applied to the nozzle row 31. In this embodiment, the depth D is set to 40 mm. Here, when the negative pressure applied by the porous body 32 and the positive head pressure corresponding to the height D are added together, the pressure in the nozzle row 31 becomes −10 to −40 mmAq, which is a pressure (negative pressure) below 0. In other words, the absolute value of the head pressure generated by the depth D is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is pressurized and ink leakage from the nozzle row 31 is suppressed.

[0055] Therefore, according to the embodiment described above, in addition to the effects described in embodiment 1, when refilling ink from an ink bottle into an ink tank, ink injection automatically stops when the maximum amount has been refilled, making the ink refill operation by the user easier. EXAMPLES

[0056] Fig. 9 is a diagram showing a schematic diagram of an ink supply configuration from an ink tank to a print head according to a third embodiment of the present invention. In Fig. 9, the same components as those in the first embodiment described with reference to Figs. 3 to 5 are given the same reference numerals, and the description thereof will be omitted. Fig. 9 shows a state in which an ink tank 8 and a print head 4 are separated from each other.

[0057] 10 is a schematic diagram showing a state in which the ink tank 8 and the print head 4 are connected to each other by a supply tube 10 in the ink supply configuration shown in FIG.

[0058] As can be seen from the above, the ink tank 8 in this embodiment is constructed so as to be detachable from the main body of the recording apparatus.

[0059] As shown in Figure 9, the ink storage section 33 of the ink tank 8 is filled with a specified amount of ink. A gas-liquid separation membrane 52 is attached to the top of the ink tank 8 in a position that covers the atmosphere communication passage. The gas-liquid separation membrane 52 is made of a material that has the property of allowing gas to pass through and blocking liquid. If the ink tank 8 is placed in a different direction from the state shown in Figure 9 (for example, rotated 90 degrees to the horizontal direction), the ink in the ink tank 8 will pass through the atmosphere communication port 28 and reach the gas-liquid separation membrane 52, but will not leak out due to the above-mentioned properties.

[0060] 9 and 10, a supply needle 51 is attached to the tip of the supply tube 10 on the main body side of the recording device 50. Meanwhile, a seal member 50 made of an elastic material such as rubber is attached to the ink tank 8. When the ink tank 8 is attached to the main body of the recording device, as shown in FIG. 10, the tip of the supply needle 51 penetrates the seal member 50, and the flow path in the supply tube 10 and the ink containing section 33 are in communication with each other.

[0061] The maximum amount of ink that can be injected into the ink tank 8 is set at a position that is higher than the nozzle row 31 by a height H in the vertical direction. Therefore, a positive head pressure of the height H is applied to the nozzle row 31. In this embodiment, the height H is set to 20 mm. Here, when the negative pressure applied by the porous body 32 and the positive head pressure of the height H are added together, the pressure in the nozzle row 31 portion is −30 to −60 mmAq, which is a pressure (negative pressure) below 0. In other words, the absolute value of the head pressure generated by the height H is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is not pressurized.

[0062] FIG. 11 is a schematic diagram showing a state in which there is no ink in the tubes even when the print head and the ink tank are connected in the ink supply configuration shown in FIG.

[0063] As shown in FIG. 11, a positive head pressure corresponding to a depth D from the highest ink level in the ink tank 8 to the bottom surface of the ink tank 8 is applied to the nozzle row 31. In this embodiment, the depth D is set to 40 mm. When the negative pressure applied by the porous body 32 and the positive head pressure corresponding to the height D are added together, the pressure in the nozzle row 31 becomes −10 to −40 mmAq, which is a pressure (negative pressure) below 0. In other words, the absolute value of the head pressure generated by the depth D is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is pressurized, and ink leakage from the nozzle row 31 is suppressed.

[0064] Therefore, according to the embodiment described above, even if the ink tank and the print head (tube) are configured to be detachable, the nozzle row of the print head can be positioned within the range of fluctuation of the ink level in the ink tank, so the height of the printing device itself can be kept low. Furthermore, even if the printing device is left unused for a long period of time, the nozzle row will not be pressurized, and a stable supply of ink is possible. This allows the printing device to be made smaller and maintains high reliability. EXAMPLES

[0065] Fig. 12 is a diagram showing a schematic configuration of an ink supply from an ink tank to a print head according to a fourth embodiment of the present invention. In Fig. 12, the same components as those in the first embodiment described with reference to Figs. 3 to 5 are given the same reference numerals, and the description thereof will be omitted.

[0066] As shown in Fig. 12, in the normal state, the buffer chambers 29-30 inside the ink tank 8 are positioned vertically above the ink containing section 33. In Fig. 12, (a) shows the state in which ink has been poured into the main tank 8, and (b) shows the state in which the ink tank 8 has been filled with ink, has been placed upside down, and has returned to the normal position (normal state) after ink has flowed into the buffer chambers 29-30.

[0067] In this embodiment, the ink is stored with a compression ratio and ink filling amount such that the negative pressure generated by the porous body 32 is −50 to −80 mmAq. As shown in FIG. 12(b), even if ink flows into the buffer chambers 29 to 30, the maximum ink level is located at a position higher than the nozzle row 31 by the height C in the vertical direction, so that a positive head pressure of the height C is applied to the nozzle row 31. In this embodiment, the height C is set to 40 mm. Therefore, when the negative pressure applied by the porous body 32 and the positive head pressure of the height C are added together, the pressure of the nozzle row 31 is −10 to −40 mmAq, which is a pressure (negative pressure) below 0. That is, the absolute value of the head pressure generated by the height C is set to be equal to or less than the absolute value of the negative pressure generated by the porous body 32. Therefore, the nozzle row 31 is pressurized and ink leakage from the nozzle row 31 is suppressed.

[0068] Therefore, according to the embodiment described above, even if the ink tank is turned upside down after being filled with ink, causing ink to flow into the buffer chamber of the ink tank and causing the ink level to be higher than the nozzle row, the nozzle row will not be pressurized. This allows for a stable supply of ink. This maintains high reliability. Also, as can be seen from the configuration shown in Figure 12, there is no need to raise the position of the nozzle row of the print head relative to the ink tank, so the height of the printing device itself can be kept low, which contributes to the miniaturization of the printing device.

[0069] In the above-described embodiment, the negative pressure generating means provided inside the recording head is the porous body 32, but the present invention is not limited to this.

[0070] FIG. 13 is a diagram showing a schematic configuration of another negative pressure generating means inside the recording head.

[0071] 13, an example is shown in which, as a means for generating negative pressure inside the recording head 4, a spring bag 54 capable of storing ink and a spring 55 biased in a direction that expands the spring bag 54 (in the direction of arrow A) are used to maintain a negative pressure state, instead of the porous body 32. This configuration further includes a valve 56 for appropriately controlling the amount of ink inside the spring bag 54. When the valve 56 is opened, ink flows into the inside of the spring bag 54 from the tube 10 and the ink liquid chamber 4a of the recording head 4 through the inlet 58. The opening and closing of the valve 56 is controlled by the rotation of a lever 57 in the direction of arrow B around a rotation axis 57a.

[0072] 13, (a) shows a state in which lever 57 abuts against end 54a of spring bag 54 and is prevented from contracting by spring 55. At this time, valve 56 is closed to block inlet 58, and ink does not flow into the inside of spring bag 54. On the other hand, (b) shows a state in which lever 57 has rotated in the direction of arrow B and is no longer abutting against end 54a, and spring bag 54 has contracted in the direction of arrow C due to the contraction of spring 55. At this time, valve 56 is opened to open inlet 58, and ink flows into the inside of spring bag 54.

[0073] The opening and closing operation of valve 56 is linked to the rotation of lever 57. When lever 57 is in contact with end 54a, valve 56 is closed, and when lever 57 is no longer in contact with end 54a, valve 56 is open.

[0074] 13(a), when the ink liquid chamber 4a of the recording head 4 and the spring bag 54 are filled with ink, the spring 55 expands in the direction of the arrow A, and as a result, the entire spring bag 54 also expands in the direction of the arrow A. At this time, the negative pressure generated by the expansion and contraction of the spring bag 54 is minimized. At this time, the valve 56 is closed, and no ink flows into the spring bag 54 from the inlet 58.

[0075] On the other hand, when ink is ejected from the nozzles of the recording head 4 and the ink inside the spring bag 54 is consumed, the contraction force of the spring 55 causes the spring bag 54 to contract in the direction of the arrow C by the amount of ink consumed, as shown in Fig. 13(b). As the spring bag 54 contracts, the contact state with the end 54a of the lever 57 loosens, the lever 57 rotates in the direction of the arrow B, and the valve 56 opens, so that ink is introduced into the recording head 4 and further flows into the inside of the spring bag 54 through the inlet 58. This inflow causes the spring bag 54 to expand again, and the spring 55 to extend in the direction of the arrow A.

[0076] When the inside of the spring bag 54 is filled with ink in this manner, the state shown in FIG. 13(a) is reached and the valve 56 is closed.

[0077] 13, even when the negative pressure generating means inside the recording head 4 is a spring bag, by storing the ink with a spring pressure and ink filling amount that results in a negative pressure of -50 to -80 mmAq, it is possible to obtain the same effect as when the negative pressure generating means is a porous body 32. In this way, a structure that utilizes the elastic force of an elastic member such as a spring may be adopted as the negative pressure generating means. [Explanation of symbols]

[0078] 1 conveyor roller, 2 pinch roller, 3 platen, 4 recording head, 5, 6 guide rail, 7 carriage, 8 ink tank, 10 supply tube, 11 recovery unit, 40 ink injection auxiliary member, 41 ink bottle, 50 Inkjet recording device, 50 Sealing member, 51 Supply needle, 52 Gas-liquid separation membrane

Claims

1. a print head including a nozzle row made up of a plurality of nozzles for ejecting ink, and a negative pressure generating means for applying a negative pressure to the nozzle row; an ink tank including a storage section for storing ink, an atmosphere communication port for communicating the storage section with the atmosphere, and an injection port for injecting ink into the storage section; a tube connecting the recording head and the ink tank and supplying ink from the ink tank to the recording head; During a recording operation in which ink is discharged from the nozzle array to record an image, the recording head and the ink tank are connected via the tube, the highest position of the ink level in the ink tank in the vertical direction is higher than the position of the nozzle row of the recording head, and the absolute value of the head pressure generated by the difference between the highest position of the ink level in the ink tank and the position of the nozzle row of the recording head is equal to or less than the absolute value of the negative pressure generated by the negative pressure generating means; The ink jet recording apparatus according to claim 1, wherein the negative pressure generating means includes a porous body or a spring bag including a spring.

2. a print head including a nozzle row made up of a plurality of nozzles for ejecting ink, and a negative pressure generating means for applying a negative pressure to the nozzle row; an ink tank including a storage section for storing ink, an atmosphere communication port for communicating the storage section with the atmosphere, and an injection port for injecting ink into the storage section; a tube connecting the recording head and the ink tank and supplying ink from the ink tank to the recording head; The ink tank includes: a buffer chamber is provided between the container and the air vent, above the container in the vertical direction, and capable of storing ink that has flowed out of the container; an ink jet recording device characterized in that the highest position of the ink level in the buffer chamber in the vertical direction is higher than the position of the nozzle row of the recording head, and the absolute value of the head pressure generated by the difference between the highest position of the ink level in the buffer chamber and the position of the nozzle row of the recording head is equal to or less than the absolute value of the negative pressure generated by the negative pressure generating means.

3. 3. The ink jet recording apparatus according to claim 2, wherein the negative pressure generating means includes a porous body or a spring bag including a spring.

4. The spring bag further comprises: An inlet through which ink flows into the inside; A valve for opening and closing the inlet; a lever for controlling opening and closing of the valve, The spring is provided to bias the spring bag to expand in a predetermined direction, The lever is provided so as to be linked to the opening and closing of the valve and the expansion and contraction of the spring, An inkjet recording device according to claim 1 or 3, characterized in that the lever opens the valve as the spring contracts due to consumption of ink in the spring bag, allowing ink to flow into the spring bag through the inlet, and when the spring bag is filled with ink, the lever closes the valve as the spring expands.

5. 5. The ink jet recording apparatus according to claim 1, further comprising a removable cap for the injection port.

6. 6. The inkjet recording apparatus according to claim 1, wherein the ink tank has a visible surface through which the ink level inside the storage portion can be visually observed, and a determining portion provided on the visible surface to determine the highest position of the ink level.

7. 6. The ink jet recording apparatus according to claim 5, wherein a cylindrical injection auxiliary member that forms an ink flow path is attached to or formed integrally with the ink tank.

8. 8. An ink jet recording apparatus according to claim 7, wherein a lower end of said ink injection auxiliary member defines a highest position of the ink level in said ink tank.

9. 9. The ink jet recording apparatus according to claim 1, wherein the atmosphere communication port is provided with a gas-liquid separation membrane.

10. the tube is connectable to and detachable from the ink tank; A needle is provided at the tip of the tube, A seal member made of an elastic material is attached to the ink tank, 10. The ink jet recording apparatus according to claim 1, wherein, when the tube is connected to the ink tank, the needle penetrates the seal member to establish communication between the tube and the ink tank.

11. 11. An inkjet recording apparatus according to claim 1, wherein the absolute value of a head pressure generated by the difference between the highest position of the ink level in the ink tank and the bottom surface of the ink tank is equal to or less than the absolute value of the negative pressure generated by the negative pressure generating means.

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