Patent Grant
8419150
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-077470, filed on Mar. 30, 2010, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an inkjet printer, and specifically relates to an inkjet printer which employs an ink circulation system and has a function of adjusting the temperature of ink circulating therein.
2. Description of the Related Art
Low-cost inkjet printers which are capable of high-speed color printing are widely used. An inkjet printer is connected to a terminal, such as a personal computer, and then takes in data of image, such as letters, illustrations and symbols, produced by the terminal, and prints the image on a sheet. With a multifunctional inkjet printer integrated with a scanner and a facsimile, image data taken in from the scanner unit or image data transferred through the facsimile can be printed.
In an inkjet printer, a temperature range which guarantees the performance of ink used for printing is specified in order to obtain a good print result. Japanese Unexamined Patent Application Publication No. 2006-88575 discloses an inkjet printer employing an ink circulation system which is configured to circulate ink therein, and is effective in guaranteeing the performance of the ink as described above. This inkjet printer includes a heater which is configured to heat the ink, and a cooler which is configured to cool the ink. When the temperature of the ink is too low to be in the temperature range which guarantees the performance of the ink, the ink is heated by using the heater. When the temperature of the ink is too high to be in the temperature range which guarantees the performance of the ink, the ink is cooled by using the cooler. The heater and the cooler are provided along an ink circulation path with the ink circulation path in between so as to make an ink circulation unit thereof smaller.
In an inkjet printer employing this type of ink circulation system, however, even if the ink flowing in the ink circulation path is heated by using the heater, the cooler which is provided side by side with the heater ends up drawing the heat from the ink. Accordingly, with poor heating efficiency as a result, it is necessary to increase heat energy from the heater in order to guarantee the performance of the ink. This leads to an increase in power consumption of the inkjet printer.
Japanese Unexamined Patent Application Publication No. 2009-255327 discloses a printing device which solves such a technical problem. This printing device includes in an ink circulation path thereof: a heater-side path which goes through a heater; a cooler-side path which goes through a cooler; a solenoid valve which is configured to switch back and forth between the heater-side path and the cooler-side path; and a controller which is configured to control the solenoid valve by software processing. The solenoid valve is driven by control coming from the controller, so that the flow of ink into the heater-side path and the flow of ink into the cooler-side path can be switched back and forth therebetween. In other words, in this printing device, it is possible to efficiently heat the ink flowing in the heater-side path by using the heater, or efficiently cool the ink flowing in the cooler-side path by using the cooler by switching the path by the solenoid valve.
However, in the printing device disclosed in Japanese Patent Application Publication No. 2009-255327, the following points are not taken into consideration. Specifically, it is necessary to install a solenoid valve which is configured to switch back and forth between the heater-side path and the cooler-side path in the ink circulation path and a control system including software which is configured to control the solenoid valve, resulting in an increase in the number of parts therefor. Further, the increase in the number of the parts makes the mechanical structure and control system of the printing device complex. As a result, the production cost and product cost of the printing device are increased.
An object of the present invention is to provide an inkjet printer employing an ink circulation system in which heating efficiency of ink circulating in an ink circulating path while maintaining cooling efficiency thereof can be increased with a simple configuration.
An aspect of the present invention is an inkjet printer comprising: an inkjet print head; a first ink circulation path connected to the print head and configured to supply ink to the print head; a second ink circulation path connected to the print head and configured to circulate ink discharged from the print head; and an ink temperature adjusting unit, wherein the ink temperature adjusting unit includes a first temperature-adjusting path connected to the first ink circulation path and the second ink circulation path for use in cooling ink discharged from the print head, and a second temperature-adjusting path connected to the second ink circulation path separately from the first temperature-adjusting path and connected to the first ink circulation path while joining the first temperature-adjusting path for use in heating ink discharged from the print head, the second temperature-adjusting path having a larger flow path resistance than a flow path resistance of the first temperature-adjusting path at least on a side thereof near the first ink circulation path.
Hereinafter, embodiments of the present invention will be described by referring to drawings. It should be noted that same or equivalent portions and components among the drawings are denoted by same or equivalent reference letters, and description thereof will be omitted or simplified. It should also be noted that the drawings are schematic, and therefore differ from actual ones.
Embodiments described hereinafter are examples of a device and a method which are used for giving a concrete form to a technical idea of the present invention, and the technical idea of the present invention does not specify arrangement and the like of respective constituent portions to those described hereinafter. The technical idea of the present invention can be variously modified within the scope of the claims of the present invention.
The first embodiment of the present invention describes an example of applying the present invention to a color inkjet printer which employs an ink circulation system. It should be noted that, in the first embodiment and examples described thereafter, an ink circulation system for an ink of a single color, for example, a black ink, will be described for easy understanding, and the configuration thereof or a similar configuration, although whose description will be omitted, is adopted for ink circulation systems of other respective colors, specifically, a cyan ink, a magenta ink and a yellow ink. In other words, four ink circulation systems which independently circulate the respective four colors are installed in the color inkjet printer. In addition, the present invention is not necessarily applied only to color inkjet printers, but can be applied to monochrome jet printers including grey scale printers.
Apparatus Configuration of Inkjet Printer
As shown in
The inkjet printer 10 includes multiple print heads 2 which each has many nozzles arranged in an orthogonal direction to a transfer direction of a sheet fed from the paper feeding table 101 or the like. The print heads 2 are configured to respectively discharge a black ink, a cyan ink, a magenta ink and a yellow ink, and thereby perform printing line by line. The inkjet printer 10 according to the first embodiment is a color inkjet printer which employs an inkjet system. It should be noted that the inkjet printer 10 according to the first embodiment is not limited to a system in which printing is performed line by line, and may be applied to a serial system in which printing is performed by scanning in a line direction.
Printing Operation of Inkjet Printer
Printing operation of the inkjet printer 10 shown in
In a region facing the print heads 2 with the paper feeding-system transfer path in between, a circular transfer belt 120 is arranged. The transfer belt 120 is configured to transfer a sheet at a speed specified according to print conditions. To a sheet transferred by using the transfer belt 120, the print heads 2 discharge inks of respective colors, and thereby color print, monochrome print or gray-scale print is performed.
A printed sheet is transferred along the paper discharging-system transfer path by the driving unit, and then directly guided to the paper receiving table 110 in the case of single side printing. Meanwhile, in the case of double side printing, a single-side printed sheet is guided to a switchback path 111 from the paper discharging-system transfer path through a switching unit 122, and the sheet is again returned to the paper feeding-system transfer path with the printed side reversed. In the same manner as in the case of single side printing, the sheet thus returned to the paper feeding-system transfer path is transferred to the print unit from the resister 121, subjected to printing, and then discharged to the paper receiving table 110 through the paper discharging-system transfer path.
Configuration of Ink Circulation System
The inkjet printer 10 according to the first embodiment includes an ink circulation system 1 shown in
The ink circulation system 1 shown in
Further, the ink circulation system 1 includes a first ink tank (upstream tank) 31, which is connected to the other end of the first ink circulation path 32, and configured to store ink supplied to the print heads 2 through the first ink circulation path 32, and a second ink tank (downstream tank) 43, which is connected to the other end of the second ink circulation path 42, and is configured to store ink discharged from the print heads 2 to be circulated through the second ink circulation path 42. Ink having a temperature adjusted through the ink temperature adjusting unit 5 so as to obtain a good print result circulates into the first ink tank 31 to be stored. The first ink tank 31 is provided with a relief valve 34 which is configured to adjust the pressure of ink circulating therein. The first ink tank 31 has a function of maintaining the flow rate and pressure of ink supplied to the print heads 2 constant. In the second ink tank 43, surplus ink which has not been used for printing in the print heads 2 is collected and stored. Between the second ink tank 43 and the ink temperature adjusting unit 5, an ink circulating pump 44 is arranged. The ink circulating pump 44 is configured to push up the ink collected in the second ink tank 43 to the first ink tank 31 through the ink temperature adjusting unit 5. Further, a pressure regulator 45 is connected to the second ink tank 43. The second ink tank 43, like the first ink tank 31, has a function of maintaining the flow rate and pressure of circulating ink.
Incidentally, although not shown in the drawing, an ink bottle which is connected to the second ink circulation path 42 or the second ink tank 43 may be arranged in the ink circulation system 1 according to the first embodiment. The ink bottle has a function of replenishing ink when the amount of circulating ink is reduced.
The print heads 2 is formed of four heads 21, 22, 23 and 24, although not limited to this number, and these heads 21 to 24 are connected to one end of the first ink circulation path 32 in parallel through an ink distributor 33. The ink distributor 33 has a function of supplying ink evenly to the heads 21 to 24 from the first ink circulation path 32. Further, the heads 21 to 24 are each connected to one end of the second ink circulation path 42 through an ink collector feeder 41. The ink collector feeder 41 has a function of collecting surplus ink which is not used in the heads 21 to 24 and supplying the ink to the second ink circulation path 42.
The heads 21 to 24 forming the print heads 2 are respectively provided with temperature detection sensors 201 to 204. The temperature detection sensors 201 to 204 are connected to a control unit 6. The temperature detection sensors 201 to 204 have a function of detecting the temperatures of ink at the heads 21 to 24, respectively, and the detected temperatures are monitored by the control unit 6. Incidentally, the temperature detection sensors 201 to 204 are provided to the heads 21 to 24 in order to most accurately measure the temperature of ink immediately before or after printing. When accuracy tolerance in temperature measurement is allowed to some extent, the temperature detection sensor may be provided to at least any one of the ink distributor 33, the ink collector feeder 41, the first ink circulation path 42, the first ink tank 31, the second ink circulation path 42, the second ink tank 43, and the like.
In the ink circulation system 1, the ink temperature adjusting unit 5 is provided between the first ink tank 31 and the second ink tank 43, more specifically between the first ink tank 31 and the second ink tank 43 through the ink circulating pump 44 in between. The first temperature-adjusting path 51 and the second temperature-adjusting path 52 in the ink temperature adjusting unit 51 are connected to the first ink circulation path 32 through the first ink tank 31, and also connected to the second ink circulation path 42 through the second ink tank 43.
The ink temperature adjusting unit 5 has therein a heating unit 56 and cooling units 54 and 55. The heating unit 56 is arranged, on the opposite side from the first temperature-adjusting path 51 (on the right side in
In the ink temperature adjusting unit 5 according to the first embodiment, a heat sink (a radiation fin in the present embodiment) made with aluminum, copper, or an alloy thereof, which has high thermal conductivity, is used for the cooling unit 54, and a cooling fan which is configured to forcibly discharge heat released from the cooling unit 54 to the outside of the inkjet printer 10 is used for the cooling unit 55. The cooling unit 54 is arranged, on the opposite side from the second temperature-adjusting path 52 (on the left side in
It should be noted that the cooling units 54 and 55 are not necessarily limited to these examples, and a cooling unit based on a water-cooling system, a cooling unit based on an electric system, or the like may be adopted. Further, a cooling system based on a combination of these systems may be also adopted.
Ink Circulation Operation of Ink Circulation System
Overall ink circulation operation of the ink circulation system 1 shown in
Firstly, ink stored in the first ink tank 31 is supplied to each of the heads 21 to 24 forming the print heads 2 through the first ink circulation path 32 and then the ink distributor 33. Ink stored in the first ink tank 31 is ink which circulated through the ink temperature adjusting unit 5, and has a temperature at which a good print result can be obtained.
In the print heads 2, ink supplied for performing printing on a sheet is consumed. Surplus ink which has not been used for the printing is collected through the ink collector feeder 41, and thus collected ink is collected through the ink circulation path 42 and stored in the second ink tank 43.
The ink stored in the second ink tank 43 is sequentially sent to the ink temperature adjusting unit 5 through the ink circulating pump 44. At this point, the ink temperature detecting sensors 201 to 204 provided to the respective print heads 2 are configured to measure the temperature of the circulating ink, and then send the result to the control unit 6. The control unit 6 is configured to determine whether or not this measurement result of the temperature of the ink is a temperature at which a good print result can be obtained, and perform control on the cooling unit 55 or the heating unit 56 on the basis of the result of the determination. When the temperature of ink is too low to be within a range which guarantees a good print result, the control unit 6 is configured to drive the heating unit 56, so that the temperature of the ink passing through the ink temperature adjusting unit 5 is adjusted to be higher. On the contrary, when the temperature of ink is too high, the temperature of the ink passing through the ink temperature adjusting unit 5 is adjusted to be lower by the cooling units 54 and 55. Incidentally, in this case, two kinds of cooling units 54 and 55 are used, and cooling may be performed by the cooling unit 54 without operating the cooling unit 55, depending on the temperature of ink circulating in the ink temperature adjusting unit 5 and the ambient temperature.
The ink whose temperature has been adjusted in the ink temperature adjusting unit 5 is circulated back to the first ink tank 31, and stored in the first ink tank 31.
Configuration of Ink Temperature Adjusting Unit
As shown in
As shown in
The second heat exchanging block 520 has a second heat exchanging path 521 therein which extends from a third surface (upper-side front surface in
In the second heat exchanging block 520, in a section from the point before reaching the third surface of the second heat exchanging path 521 to the third surface, that is, a portion of the second heat exchanging path 521 on the first ink circulation path 32 side, a resistance path 522 is arranged which is configured to increase a flow-path resistance of the second heat exchanging path 521. The ink temperature adjusting unit 5 according to the first embodiment employs a mechanism in which ink is circulated simultaneously in the first temperature-adjusting path 51 and the second temperature-adjusting path 52 during circulation of the ink, and therefore ink is always being circulated (flowing) in the first temperature-adjusting path 51 and the second temperature-adjusting path 52. With the resistance path 522 provided to the second temperature-adjusting path 52, the flow path resistance of the second temperature-adjusting path 52 is higher than the flow path resistance of the first temperature-adjusting path 51, in the case where the temperatures of the inks circulating in the first temperature-adjusting path 51 and the second temperature-adjusting path 52 are equal to each other. Further, with the resistance path 522 provided to the second temperature-adjusting path 52, the flow rate of the ink circulating in the second temperature-adjusting path 52 is larger than the flow rate of the ink circulating in the first temperature-adjusting path 51, in the case where the temperature of the ink circulating in the second temperature-adjusting path 52 is higher by a prescribed number of degrees than the temperature of the ink circulating in the first temperature-adjusting path 51.
The ink temperature adjusting unit 5 according to the first embodiment has a function of allowing self adjustment by ink itself of the flow rates thereof circulating in the first temperature-adjusting path 51 and the second temperature-adjusting path 52 by adjusting the temperatures of inks circulating the first temperature-adjusting path 51 and the second temperature-adjusting path 52, respectively, on the basis of the characteristics of ink of reducing its flow path resistance as the temperature of the ink increases. In other words, the ink temperature adjusting unit 5 has the following function. The ink temperature adjusting unit 5 automatically increases the flow rate of the ink circulating in the first temperature-adjusting path 51 used for cooling the ink, when the temperature of the ink is higher than the temperature range in which a good print result can be obtained, and automatically increases the flow rate of the ink circulating in the second temperature-adjusting path 52 used for heating the ink, when the temperature of the ink is lower than the temperature range in which a good print result can be obtained. Accordingly, it is not necessary to assemble mechanical means, such as a solenoid valve, and a control system to control a solenoid valve, for the adjustment of the flow rate of the ink circulating the first temperature-adjusting path 51 and the second temperature-adjusting path 52.
The resistance path 522 according to the first embodiment is formed into a similar shape having the same square shape as the shape of the opening of the second heat exchanging path 521 and a size smaller than the opening, and has a uniform cross section along the path. A modification example of the resistance path 522 will be described later.
The confluence unit 532 of the ink temperature adjusting unit 5 is provided on the first surface of the first heat exchanging block 510 and the third surface of the second heat exchanging block 520, that is, in an upper portion in
The branching unit 531 is provided on the second surface of the first heat exchanging block 510 and the fourth surface of the second heat exchanging block 520, that is, in a lower side portion in
The first temperature-adjusting path 51, which is configured to be used for cooling ink, in the ink temperature adjusting unit 5 according to the first embodiment is formed by connecting the first branching path 5311 of the branching unit 531, the first heat exchanging path 511 of the first heat exchanging block 510, and the first confluence path 5321 of the confluence unit 532. Similarly, the second temperature-adjusting path 52 which is configured to be used for heating ink is formed by connecting the second branching path 5312 of the branching unit 531, the second heat exchanging path 521 and the resistance path 522 of the second heat exchanging block 520, and the second confluence path 5322 of the confluence unit 532.
Being arranged apart from each other with an appropriate space in between, the first heat exchanging block 510 and the second heat exchanging block 520 in this state are clamped together by a holder 57. Air having low thermal conductivity goes into the space between the first heat exchanging block 510 and the second heat exchanging block 520, and these are thermally isolated from each other by this air. In other words, heat exchange is unlikely to occur between the first heat exchanging block 510 and the second heat exchanging block 520; therefore, both cooling efficiency and heating efficiency of the ink can be improved.
The holder 57 extends along two opposed lateral surfaces of the first heat exchanging block 510, two opposed lateral surfaces of the second heat exchanging block 520, and a lateral surface, which is located on the heating unit 56 side, of the second heat exchanging block 520. The holder 57 has a squared U shape when viewed from the top. The holder 57 is arranged in such a manner as to surround the heating unit 56 located between the holder 57 and the second heat exchanging block 520, and configured to efficiently transfer heat generated from the heating unit 56 to the second heat exchanging block 520. The holder 57 is manufactured by performing a bending process on a metal material, for example. Alternatively, the holder 57 may be manufactured from a resin material, for example, by molding.
Ink Circulation Operation of Ink Temperature Adjusting Unit
Overall ink circulation operation of the ink temperature adjusting unit 5 according to the first embodiment is as follows. The ink temperature adjusting unit 5 shown in
At this point, if there is almost no difference between the temperatures of the inks flowing in the first temperature-adjusting path 51 and the second temperature-adjusting path 52, respectively, the flow rate of the ink flowing in the second temperature-adjusting path 52 is smaller than the flow rate of the ink flowing in the first temperature-adjusting path 51 because the resistance path 522 is provided to the second temperature-adjusting path 52.
The ink temperature adjusting unit 5 shown in
As the temperature of the ink goes up by the operation of the heating unit 56, the viscosity of the ink goes down, thereby reducing the flow path resistance of the ink. Accordingly, as shown in
The ink temperature adjusting unit 5 shown in
For example, in the ink temperature adjusting unit 5 shown in
As described above, the ink temperature adjusting unit 5 has the first temperature-adjusting path 51 and the second temperature-adjusting path 52 which branch off from the second ink circulation path 42 and come together in the first ink circulation path 32. Further, in the ink temperature adjusting unit 5, the resistance path 522 is provided to the second temperature-adjusting path 52. Accordingly, in the ink temperature adjusting unit 5, based on the characteristics of ink of reducing the flow path resistance as the temperature of the ink goes up, the ink temperature adjusting unit 5 allows self adjustment of the circulation flow rate of ink flowing in the first temperature-adjusting path 51 and the second temperature-adjusting path 52 (ink itself can automatically adjust the flow rate). In other words, the ink temperature adjusting unit 5 increases the flow rate of ink flowing in the first temperature-adjusting path 51, which is configured to be used for cooling, by the self adjustment to thereby enhance the cooling efficiency, when the temperature of the ink is high. When the temperature of the ink is low, the ink temperature adjusting unit 5 increases the flow rate of the ink flowing in the second temperature-adjusting path 52, which is configured to be used for heating, by the self adjustment to enhance the heating efficiency. Relationship between the flow rate of ink and the flow path resistance in the ink temperature adjusting unit
Next, in the ink temperature adjusting unit 5 according to the first embodiment, one example of the specific relationship between the flow rate of the ink flowing in the first temperature-adjusting path 51 and the second temperature-adjusting path 52 and the resistance path 522 is as follows.
In the ink temperature adjusting unit (model) 5 used for calculation in this section, as shown in
Meanwhile, the length of the second heat exchanging block 520, which is configured to be used for heating, in an ink circulation direction is L as in the first heat exchanging block 510. The length from the fourth surface of the second heat exchanging path 521 of the second temperature-adjusting path 52 is L1, the shape of an opening of the second heat exchanging path 521 is set to be circular, and the diameter thereof is ΦB1. The length from the third surface of the resistance path 522 provided to the second heat exchanging path 521 is L2, the shape of an opening of the resistance path 522 is set to be circular, and the diameter thereof is ΦB2. In the second heat exchanging block 520, a total of six second heat exchanging paths 521 is arranged in parallel to each other at equal intervals, and a total of six resistance paths 522 is similarly arranged in parallel to each other at equal intervals in such a manner as to be directly connected to the second heat exchanging paths 521. The second heat exchanging block 520 is expressed as “heat exchanger B” in the description below based on
In the ink circulation system 1 according to the first embodiment, as shown in
In each of the first heat exchanging path 511, the second heat exchanging path 521, and the resistance path 522, the ink flow rate (mL/s) and the flow path resistance (Pa·s/m3) are calculated according to the procedure below. First, the pressure loss within a laminar circular pipe of the path is calculated according to the following equation (1).
ΔP=8·μ·u·l/r2 (1)
Here, in the equation (1), ΔP represents pressure difference, μ represents a viscosity coefficient, u represents an average flow rate, l represents a path length (L, L1 or L2), and r represents a radius (ΦA/2, ΦB1/2 or ΦB2/2). The flow rate inside the circular pipe in the path is calculated according to the following equation (2).
Q=u·A=u·(π·r2) (2)
In the equation (2), Q represents the flow rate within the path, and A represents a cross-sectional area in the circular pipe of the path. The equation (2) used for the calculation of the flow rate can be expressed by the following equation (3) including the pressure loss and flow path resistance of the path.
Q=ΔP/R (3)
In the equation (3), R represents the flow path resistance of the path. By substituting the equations (1) and (2) into the equation (3) and expanding the result, the flow path resistance can be calculated according to the following equation (4).
R=8·μ·l/(π·r4) (4)
Using the above equations, temperature dependencies of the flow rate of the ink circulating in the first heat exchanging path 511 and the second heat exchanging path 521 of the ink temperature adjusting unit 5 and the flow path resistance can be calculated as shown in
(1) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Temperature of the Ink is the Same (at a Low Temperature)
When the ink temperature adjusting unit 5 is in the state shown in
Flow path resistance of 6 first heat exchanging paths 511: 1.433×10−4 Pa·s/m3
Flow path resistance of 6 second heat exchanging paths 521: 9.077×10−5 Pa·s/m3
Flow path resistance of 6 resistance paths 522: 5.815×10−5 Pa·s/m3
Sum of flow path resistances: 7.303×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.529 mL/s
Flow rate of the heat exchanger B: 1.471 mL/s
Ratio of flow rate: 0.96
According to these calculation results, when the temperatures of the inks flowing in the first heat exchanging path 511 and the second heat exchanging path 521, respectively, in the ink temperature adjusting unit 5 are equal to each other, the flow rate of ink flowing in the second heat exchanging path 521 is smaller because there is a flow path resistance attributed to the resistance path 522. The flow rate of the ink flowing in the second heat exchanging path 521 is 0.96 times the flow rate of the ink flowing in the first heat exchanging path 511.
(2) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Ink is Heated
When the ink temperature adjusting unit 5 is in the state shown in
Sum of flow path resistances: 6.625×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.387 mL/s
Flow rate of the heat exchanger B: 1.613 mL/s
Ratio of flow rate: 1.16
According to these calculation results, in the ink temperature adjusting unit 5, when the heating unit 56 is put into operation, and thereby the second temperature-adjusting path 52 is heated, the viscosity of the ink flowing in the second temperature-adjusting path 52 including the resistance path 522 decreases, the flow path resistance decreases, and therefore the flow rate of the ink flowing in the second heat exchanging path 521 increases. Accordingly, the flow rate of the ink flowing in the first heat exchanging path 511 relatively decreases. The flow rate of the ink flowing in the second heat exchanging path 521 reaches 1.16 times the flow rate of the ink flowing in the first heat exchanging path 511.
(3) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Temperature of the Ink is the Same (at a High Temperature)
When the ink temperature adjusting unit 5 is in the state shown in
Flow path resistance of 6 first heat exchanging paths 511: 5.140×10−5 Pa·s/m3
Flow path resistance of 6 second heat exchanging paths 521: 3.256×10−5 Pa·s/m3
Flow path resistance of 6 resistance paths 522: 2.086×10−5 Pa·s/m3
Sum of flow path resistances: 2.619×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.529 mL/s
Flow rate of the heat exchanger B: 1.471 mL/s
Ratio of flow rate: 0.96
According to these calculation results, when the temperatures of the inks flowing in the first temperature-adjusting path 51 and the second temperature-adjusting path 52, respectively, in the ink temperature adjusting unit 5 are equal to each other, as in the calculation results in (1) described above, the flow rate of ink flowing in the second heat exchanging path 521 is smaller because there is a flow path resistance attributed to the resistance path 522. The flow rate of the ink flowing in the second heat exchanging path 521 is 0.96 times the flow rate of the ink flowing in the first heat exchanging path 511.
(4) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Ink is Cooled
When the ink temperature adjusting unit 5 is in the state shown in
Sum of flow path resistances: 2.713×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.476 mL/s
Flow rate of the heat exchanger B: 1.524 mL/s
Ratio of flow rate: 1.03
According to these calculation results, in the ink temperature adjusting unit 5, when operating the cooling unit 54 or the cooling unit 54 in combination with the cooling unit 55, thereby cooling the first temperature-adjusting path 51, the viscosity of the ink flowing in the second heat exchanging path 521 including the resistance path 522 increases, the flow path resistance increases, and therefore the flow rate of the ink flowing in the second heat exchanging path 521 decreases. Accordingly, the flow rate of the ink flowing in the first heat exchanging path 511 relatively increases. The flow rate of the ink flowing in the second heat exchanging path 521 drops to be 1.03 times the flow rate of the ink flowing in the first heat exchanging path 511.
(5) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Temperature of the Ink is the Same (at a Low Temperature)
When the ink temperature adjusting unit 5 is in the state shown in
Flow path resistance of 6 first heat exchanging paths 511: 4.530×10−4 Pa·s/m3
Flow path resistance of 6 second heat exchanging paths 521: 9.077×10−5 Pa·s/m3
Flow path resistance of 6 resistance paths 522: 4.055×10−4 Pa·s/m3
Sum of flow path resistances: 2.368×10−4 Pa·s/m3
Flow rate of the heat exchanger A: 1.568 mL/s
Flow rate of the heat exchanger B: 1.432 mL/s
Ratio of flow rate: 0.91
According to these calculation results, when the temperatures of the inks flowing in the first heat exchanging path 511 and the second heat exchanging path 521, respectively, in the ink temperature adjusting unit 5 are equal to each other, the flow rate of ink flowing in the second heat exchanging path 521 is smaller because there is a flow path resistance attributed to the resistance path 522. The flow rate of the ink flowing in the second heat exchanging path 521 is 0.91 times the flow rate of the ink flowing in the first heat exchanging path 511.
(6) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Ink is Heated
When the ink temperature adjusting unit 5 is in the state shown in
Sum of flow path resistances: 1.865×10−4 Pa·s/m3
Flow rate of the heat exchanger A: 1.235 mL/s
Flow rate of the heat exchanger B: 1.765 mL/s
Ratio of flow rate: 1.43
According to these calculation results, in the ink temperature adjusting unit 5, when the heating unit 56 is put into operation, and thereby the second temperature-adjusting path 52 is heated, the viscosity of the ink flowing in the second temperature-adjusting path 52 including the resistance path 522 decreases, the flow path resistance decreases, and therefore the flow rate of the ink flowing in the second heat exchanging path 521 increases. Accordingly, the flow rate of the ink flowing in the first heat exchanging path 511 relatively decreases. The flow rate of the ink flowing in the second heat exchanging path 521 reaches 1.43 times the flow rate of the ink flowing in the first heat exchanging path 511.
In the example shown in
(7) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Temperature of the Ink is the Same (at a High Temperature)
When the ink temperature adjusting unit 5 is in the state shown in
Flow path resistance of 6 first heat exchanging paths 511: 1.625×10−4 Pa·s/m3
Flow path resistance of 6 second heat exchanging paths 521: 3.256×10−5 Pa·s/m3
Flow path resistance of 6 resistance paths 522: 1.454×10−4 Pa·s/m3
Sum of flow path resistances: 8.494×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.568 mL/s
Flow rate of the heat exchanger B: 1.432 mL/s
Ratio of flow rate: 0.91
According to these calculation results, when the temperatures of the inks flowing in the first temperature-adjusting path 51 and the second temperature-adjusting path 52, respectively, in the ink temperature adjusting unit 5 are equal to each other, the flow rate of ink flowing in the second heat exchanging path 521 is reduced because there is a flow path resistance attributed to the resistance path 522. The flow rate of the ink flowing in the second heat exchanging path 521 is 0.91 times the flow rate of the ink flowing in the first heat exchanging path 511.
(8) Relationship Between the Flow Rate of Ink and the Flow Path Resistance when the Ink is Cooled
When the ink temperature adjusting unit 5 is in the state shown in
Sum of flow path resistances: 8.806×10−5 Pa·s/m3
Flow rate of the heat exchanger A: 1.516 mL/s
Flow rate of the heat exchanger B: 1.484 mL/s
Ratio of flow rate: 0.98
According to these calculation results, in the ink temperature adjusting unit 5, when operating the cooling unit 54 or the cooling unit 54 in combination with the cooling unit 55, thereby cooling the first temperature-adjusting path 51, the viscosity of the ink flowing in the second heat exchanging path 521 including the resistance path 522 increases, the flow path resistance increases, and therefore the flow rate of the ink flowing in the second heat exchanging path 521 decreases. Accordingly, the flow rate of the ink flowing in the first heat exchanging path 511 relatively increases. The flow rate of the ink flowing in the second heat exchanging path 521 drops to be 0.98 times the flow rate of the ink flowing in the first heat exchanging path 511.
Modification Examples of the Ink Temperature Adjusting Unit
Regarding the inkjet printer 10 according to the first embodiment described above, the resistance path 522 of the ink temperature adjusting unit 5 can be modified as shown in a first modification example to a twelfth modification example which will be described below.
As shown in
In the ink temperature adjusting unit 5 according to a second modification example as shown in
In the ink temperature adjusting unit 5 according to a third modification example as shown in
In the ink temperature adjusting unit 5 according to a fourth modification example as shown in
The ink temperature adjusting unit 5 according to a fifth modification example, as shown in
In the ink temperature adjusting unit 5 according to a sixth modification example as shown in
In the ink temperature adjusting unit 5 according to a seventh modification example as shown in
In the ink temperature adjusting unit 5 according to an eighth modification example as shown in
In the ink temperature adjusting unit 5 according to a ninth modification example as shown in
In the ink temperature adjusting unit 5 according to a tenth modification example as shown in
In the ink temperature adjusting unit 5 according to an eleventh modification example as shown in
In the ink temperature adjusting unit 5 according to a twelfth modification example as shown in
As described above, the inkjet printer 10 according to the first embodiment includes: the first temperature-adjusting path 51 and the second temperature-adjusting path 52 through which circulation of ink from the second ink circulation path 42 branch off and come together at the first ink circulation path 32; the resistance path 522 in the second temperature-adjusting path 52; and the ink temperature adjusting unit 5 which allows self adjustment of the circulation flow rate of ink. In the ink temperature adjusting unit 5, the flow rate of the ink flowing in the second temperature-adjusting path 52 can be automatically increased when the circulating ink is to be heated, and the flow rate of the ink flowing in the first temperature-adjusting path 51 can be automatically increased when the ink is to be cooled. Accordingly, it is possible to improve the heating efficiency and cooling efficiency of the ink circulating in the ink circulation system 1 in a simple structure without using a solenoid valve together with a control system thereof.
Further, as having such a simple structure, the ink temperature adjusting unit 5 according to the first embodiment can be easily manufactured; therefore, the production cost thereof can be reduced. As a result, the inkjet printer 10 has a simpler structure, and therefore can be easily manufactured; thus, the production cost can be reduced.
Further, in the ink temperature adjusting unit 5 according to the first embodiment, the branching unit 531, which is configured to divide ink, and the confluence unit 532, which is configured to assemble (get together) ink, both having a slightly complicated inner path are provided as independent parts from the first heat exchanging block 510 and the second heat exchanging block 520 which are used for heat exchange. Accordingly, the production can be easily performed.
A second embodiment of the present invention describes an example in which the arrangement position of the heating unit 56 in the ink temperature adjusting unit 5 of the inkjet printer 10 according to the first embodiment described above is changed.
In the ink temperature adjusting unit 5 according to the second embodiment as shown in
The ink temperature adjusting unit 5, having such a configuration, of the inkjet printer 10 according to the second embodiment has the heating unit 56 arranged between the first heat exchanging block 510 and the second heat exchanging block 520. With the heating unit 56 thus arranged, the heat transfer path between the first heat exchanging block 510 and the second heat exchanging block 520 is blocked, so that heat of the ink flowing in the second heat exchanging path 521 of the second heat exchanging block is prevented from flowing toward the first heat exchanging block 510. Moreover, the second heat exchanging path 521 is heated from the first heat exchanging block 510 side, so that the heating efficiency of the ink flowing in the second heat exchanging path 521 can be improved.
A third embodiment of the present invention describes an example in which the ink temperature adjusting unit 5 of the inkjet printer 10 according to the first embodiment and the ink temperature adjusting unit 5 of the inkjet printer 10 according to the second embodiment described above are combined.
The ink temperature adjusting unit 5 according to the third embodiment as shown in
In the ink temperature adjusting unit 5, having such a configuration, of the inkjet printer 10 according to the third embodiment, an effect obtained by combining the effect obtained with the ink temperature adjusting unit 5 according to the first embodiment and the effect obtained with the ink temperature adjusting unit 5 according to the second embodiment can be obtained.
As described above, the present invention has been described by using the first to third embodiments. However, the description and drawings which constitute part of this disclosure do not limit the present invention. The present invention can be applied to various alternative embodiments, examples and operation techniques. For example, the ink temperature adjusting unit 5 according to the examples above has the first temperature-adjusting path 51 which is configured to cool circulating ink and the second temperature-adjusting path 52 which is configured to heat the ink. However, the present invention may further include a third temperature-adjusting path which is configured to achieve a temperature between those achieved by the cooling and heating described in the above examples, or more temperature-adjusting paths.
In addition, the ink temperature adjusting unit 5 according to the examples described above has two cooling units 54 and 55; however, the present invention only needs to include one of the cooling units 54 and 55.
Moreover, as described in the beginning, the present invention is not limited to a color inkjet printer, and also applicable to a monochrome inkjet printer. In addition, the present invention can be applied to a multifunctional inkjet printer which has a scanner function and/or a facsimile function.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2010-077470 | Mar 2010 | JP | national |
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|---|---|---|---|
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| Number | Date | Country |
|---|---|---|
| 2006-088575 | Apr 2004 | JP |
| 2009-255327 | Nov 2009 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20110242155 A1 | Oct 2011 | US |
