Ink jet recording device

Abstract: An ink jet recording device has heating device (14a, 14b, 15a, 15b, 19, 20) for heating ink at a suction pipe (10), a suction pump (12) or a cap member (9). With this structure, an unsatisfactory operation of the ink jet recording device due to coagulation of ink can be prevented even when heat melting ink, or ink presenting plastic-flowability at the ordinary temperature, is used for the ink jet recording device.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a structure of an ink jet recording device provided with a maintenance device for sucking ink drops, dust etc. stagnating in a recording head in order to recover from unsatisfactory ink jet using heat melting ink or ink which presents plastic-flowability at the ordinary temperature. Description of the Background Art An ink jet recording device of ink jet method where recording is performed by jetting ink drops from a plurality of ink jet outlets onto recording paper is widely used for a printer, facsimile, word processor etc. A recording head for the ink jet recording device includes those performing black-and-white printing and color printing which is adapted to accommodate ink of different colors. An example of a conventional jet recording device is disclosed, for example, in Japanese Patent Laying-Open No. 4-133750. Fig. 7 is a schematic perspective view illustrating a structure of the ink recording device. A carriage 63 is provided such that carriage 63 can reciprocate along a guide shaft 61 by a driving belt 62. On carriage 63, a recording head 65 which is provided with an ink tank 64 is mounted. Recording head 65 performs printing on recording paper 67 which is carried to the front side of a platen roller 66. A wiping blade 68 suitably abuts against recording head 65 and removes ink drops and dust adhering to recording head 65. A cap 69 seals recording head 65 in a manner that head 65 is covered with cap 69 in order to protect head 65 when printing by head 65 is not performed, and sucks ink drops and dust stagnating in head 65 using a suction pump within a suction unit 71 which is connected to cap 69 via a suction pipe 70 when printing is unsatisfactorily performed. The ink drops and dust which are sucked by suction unit 71 are collected in waste ink unit 73. This recovers printing performance of recording head 65. Now Fig. 8 is a schematic diagram illustrating the internal structure of suction unit 71. A suction pump 72, referred to as a tube pump, is provided in suction unit 71. A plurality of rollers 76a, 76b, 76c are rotatably attached to suction pump 72 around a rotor 75 which is driven by a motor. Each of rollers 76a, 76b, 76c can rotate about its center as a rotation axis. A tube 78 which deforms elastically is provided between a pump case 72A and rotor 75. With rotor 75 rotating in the direction of the arrows shown in the figure, rollers 76a, 76b, 76c rotate while pressing against tube 78. This will generate negative pressure on the side of cap 69, and ink drops and dust are sucked from recording head 65 abutting against cap 69. The ink drops and other wastes sucked by suction pump 72 pass through from a tube 78a to a tube 78b, are sent to a waste ink unit 73 and collected there. In the ink jet recording device described above, if ink within a nozzle of the recording head is mixed with air bubbles, dust, etc., ink jet at the recording head would be unsatisfactory. The unsatisfactory ink jet causes missing and displacement of printing dots. This causes the problem that quality of printing by the recording head will deteriorate. In order to solve this problem, means have been taken for recovering printing performance of the recording head, by covering cap 69 with recording head 75 and sucking the recording head using a suction pump communicated with cap 69, so that air bubbles and dust can be sucked together with ink drops within recording head 75. On the other hand, when heat melting ink is used for the ink jet recording device, high quality printing can be achieved, since the ink drops on recording paper bleed only to a small extent. When heat melting ink is used in the ink jet recording device, the heat melting ink will be cooled and coagulate within the suction pipe while the head is being sucked if the head is sucked using a conventional suction unit. As a result, the suction pipe will be clogged and the ink drops cannot be sucked. Furthermore, even if heat melting ink is sucked successfully, the heat melting ink which remains within the suction pump will be cooled and coagulate. As a result, the problem arises that the rotor and rollers within the suction pump will be stuck and that the suction pump cannot be used. In other words, in the ink jet recording device using heat melting ink which is solid at the ordinary temperature and is heated for use, or ink which presents plastic-flowability at the ordinary temperature and is heated for use in printing, there has been a problem that the performance of the suction unit will deteriorate. Document EP-A-0,574,268 discloses an ink jet device which is provided with heaters 4a-4d on the head side. Furthermore, heater 24 as means for heating the cap is provided on the cap side and thus independent in configuration of the head. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording device provided with a maintenance device which can prevent coagulation of ink in a suction unit even when heat melting ink or ink presenting plastic-flowability at the ordinary temperature is used as recording ink. In order to achieve the above object, the ink jet recording device of the present invention is provided with a cap member for covering a jet portion which jets ink of a recording head; a waste ink tank for collecting waste ink; an ink suction pipe connecting the cap member with the waste ink tank for sucking and draining out waste ink adhering to the recording head; and a suction device connected to the ink suction pipe; wherein the suction pipe is provided with a heating device for heating the waste ink. According to the structure with the suction pipe being provided with the heating device, even when ink presenting solidity or plastic-flowability at the ordinary temperature is used for the ink jet recording device, the heating device will heat the ink up and make the ink flow easily, so that the ink can be sucked, never clogging the suction pipe. Also, an unsatisfactory operation of the suction unit due to the clog of the suction pipe with ink can be prevented. Furthermore, if the ink which was sucked previously presents plastic-flowability at the time of power-on of the suction unit, the ink can be fluidized and sucked by heating the suction pipe with the heating device. As a result, high accuracy of performance of the suction unit can be always maintained. Furthermore, a heater line is preferably provided within the suction pipe as the heating device for the suction pipe. This allows heat to be efficiently transferred to the ink within the suction pipe if the suction pipe is made of a material of a low heat conductivity. Furthermore, melting rate of the ink can be accelerated by providing the heater line spirally within the suction pipe and increasing the contact area of the heater line with the ink. Furthermore, if the thickness of the suction pipe is thin, the spiral heater line could prevent the suction pipe from being broken due to negative pressure generated by the suction pump. Still preferably, the suction pipe is made of metal and provided with the heating device on the circumference of the suction pipe. According to this structure with the suction pipe made of metal, the conductivity of the suction pipe will be improved. Accordingly, the suction pipe can be externally heated efficiently. Also, if a heater is provided at a portion of the suction pipe, the entire suction pipe will be heated rapidly, allowing for miniaturization of the heating device. According to another aspect of the ink jet recording device of the present invention for achieving the object described above, the ink jet recording device is provided with a cap member for covering a jet portion which jets ink of a recording head; a waste ink tank for collecting waste ink; an ink suction pipe connecting the cap with the waste ink tank for sucking and removing waste ink adhering to the recording head; and a suction device connected to the ink suction pipe; wherein the suction device is provided with a heating device for heating the waste ink. According to the structure with the suction device being provided with the heating device, even in the case of ink presenting solidity or plastic-flowability at the ordinary temperature, the heating device will heat the waste ink up and make the ink flow easily. As a result, the waste ink can be sucked without the suction pipe being clogged. Also, an unsatisfactory operation of the suction unit due to the clog of the suction device with ink can be prevented. Furthermore, if the ink which was sucked previously is solid or presents plastic-flowability at the time of power-on of the suction unit, the ink can be fluidized and then sucked by heating the suction device, and high accuracy of performance of the suction unit can be always maintained. Still preferably, the suction device is a tube pump provided with a pipe member part of which is formed of elastic body, and with a pressurizing roller which produces negative pressure in the pipe member by pressurizing the pipe member externally while moving the pressurized portion. Accordingly, since the pipe member and the pressurizing roller are separated completely, infiltration of the ink into the pressurizing roller portion can be avoided, thereby preventing an unsatisfactory operation of the suction pipe due to the infiltration of the ink into the pressurizing roller portion. Still preferably, the tube pump has ring-shaped heating device a heat source of which is an infra-red lamp. This allows the heating device to heat the pipe member and the pressurizing roller without contacting the pressurizing roller portion of the tube pump, and therefore the damage of the heating device due to an action of the suction pump can be prevented. Still preferably, the ink jet recording device is provided with a cap member for covering a jet portion which jets ink of a recording head wherein the cap member is provided with a heating device for heating the waste ink. According to the structure with the cap member being provided with the heating device, even when ink presenting solidity or plastic-flowability at the ordinary temperature is used for the ink jet recording device, the ink will be heated by the heating device and be made to flow easily. Accordingly, the ink can be sucked without stagnating around the cap member, so that an unsatisfactory operation of the suction unit due to the clog of the cap member with ink can be prevented. Furthermore, if waste ink sucked previously presents solidity or plastic-flowability in the cap member at the time of power-on of the suction unit, the waste ink can be fluidized and then sucked by heating the cap member, and high accuracy of performance of the suction unit can be always maintained. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of the structure of the ink jet recording device in accordance with the present invention. Fig. 2 is a diagram showing a first embodiment in which the suction pipe is provided with the heating device. Fig. 3 is a diagram showing a second embodiment in which the suction pipe is provided with the heating device. Fig. 4 is a diagram showing a third embodiment in which the suction pipe is provided with the heating device. Fig. 5 is a cross sectional view taken along the line X-X in Fig. 4. Fig. 6 is a diagram of a fourth embodiment in which the cap member is provided with the heating device. Fig. 7 is a schematic diagram illustrating a structure of a conventional ink jet recording device. Fig. 8 is a schematic view illustrating an internal structure of a conventional suction unit. DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter a first embodiment of the ink jet recording device in accordance with the present invention will be described with reference to Figs. 1 and 2. First, referring to Fig. 1, the outline of the ink jet recording device of the first embodiment will be described. A carriage 3 can reciprocate along a guide shaft 1 by a driving belt 2. On carriage 3, a recording head 5 which is provided with an ink tank 4 is mounted. Recording head 5 performs printing on a sheet of recording paper 7 which is carried to the front side of a platen roller 6. A wiping blade 8 abuts against recording head 5 as required and removes ink drops and dust adhering to recording head 5. A cap 9 seals and protects recording head 5 when printing by head 5 on printing paper 7 is not performed, and sucks the drops and dust within head 5 using a suction pump within a suction unit 11 which is connected to cap 9 via a suction pipe 10 when printing is performed unsatisfactorily. This recovers printing performance of recording head 5. The ink sucked by the suction pump using the cap 9 is collected in a waste ink unit 13 connected to suction unit 11. Now, referring to Fig. 2, the structure of a suction pump 12 provided within suction unit 11 will be described. Suction pump 12 is connected between suction pipes 10a and 10b. One end of suction pipe 10a is connected to cap 9 and one end of suction pipe 10b is connected to waste ink unit 13. The principle of operation of suction pump 12 is not repeated here, since it is the same as that of the suction pump described with reference to Fig. 8. Heater lines 14a, 14b are inserted within suction pipes 10a, 10b and are connected to an external power supply source. Thus, by providing heater lines 14a, 14b directly inside suction pipes 10a, 10b, even ink presenting solidity or plastic-flowability at the ordinary temperature is heated by the heater lines, so that the ink can always flows easily. As a result, ink can be sucked without clogging suction pipe 10a, 10b with ink, so that an unsatisfactory operation of suction unit 11 due to the clogged suction pipes 10a, 10b can be prevented. Furthermore, the amount of ink in contact with the heater lines is increased as the heater lines are provided spirally within the suction pipe so that melting temperature of the ink can be increased. Also the spiral heater lines can prevent the suction pipes from being damaged due to negative pressure caused by the suction pump. Furthermore, even when a suction pipe made of resin with low heat conductivity is used, heat can be transferred to the ink efficiently since the heater lines are provided directly within the suction pipe. (Second Embodiment) A second embodiment in accordance with the present invention will now be described with reference to Fig. 3. While suction pipes 10a, 10b in the first embodiment are provided with the heater lines, a suction pipe made of metal such as stainless steel is used for suction pipes 10c, 10d in the ink jet recording device of the second embodiment. Furthermore, suction pipes 10c, 10d made of stainless steel are provided with external heating devices 15a, 15b for heating suction pipes 10c, 10d. Thus, it is not necessary to heat up the entire suction pipes by utilizing stainless steel which is a metal having good heat conductivity, and therefore the entire pipes can be heated sufficiently by providing the heating devices only at a portion of the suction pipes. This allows miniaturization of the heating devices and therefore of suction unit 11. [Third Embodiment] A third embodiment according to the present invention will be now described with reference to Figs. 4 and 5. As already described with reference to Fig. 8, in this embodiment of Figs. 4 and 5 also, suction pipe 12 has a plurality of rollers 16a, 16b, 16c attached around rotor 15 which is driven by a motor. Each of rollers 16a, 16b, 16c can rotate about its center as a rotation axis. A tube 18 is provided between rotor 15 and a pump case 17. Tube 18 is compressed by rollers 16a, 16b, 16c. When rotor 15 rotates, those portions of tube 18 which are compressed by rollers 16a, 16b, 16c will be moved to the side of a waste ink tank 13, thereby producing negative pressure on the side of cap 9 so that the ink may be sucked. For this embodiment, a ring-shaped heating device 19 is provided at one side of pump case 17. A ring-shaped infra-red lamp is embedded in heating device 19 and radiates infra-red rays to rollers 16a, 16b, 16c and tube 18 to heat them. Further, rollers 16a, 16b, 16c heat indirectly those portions of tube 18 which are pressed against by the rollers. For this reason, rollers 16a, 16b, 16c made of a metal having low specific heat are preferable, since such a metal will make shorter the time required for increasing the temperature of rollers 16a, 16b, 16c. Thus, ring-shaped heating device 19 can heat the tube and rollers without contacting the motor portion. Accordingly, there will not be the possibility that an operation of suction pump 12 will move the heating device and cause disconnection. This enhances the reliability of suction unit 11. [Fourth Embodiment] A fourth embodiment in accordance with the present invention will now be described with reference to Fig. 6. In the fourth embodiment, an embodiment in which cap 9 is heated is disclosed. In ink tank 4 held to carriage 3 of the ink jet recording device, a heater 22 is provided for heating and fluidizing heat melting ink or plastic-flowability ink 21. Furthermore, a heater 23 is provided so that heater 23 can heat recording head 5 to maintain the temperature at which the ink can be jetted. Cap 9 is formed of a metal having high heat conductivity such as stainless steel. Accordingly, when cap 9 is fitted to recording head 5, heat from heaters 22 and 23 will be transferred to cap 9 and heat it. Thus, cap 9 can be heated by using the heaters provided in ink tank 4 and will not necessitate another heat source for it. Therefore, the ink can be prevented from coagulating at the cap portion.

Claims: An ink jet recording device which performs recording by using a recording head (5) jetting ink to a recording medium (7), comprising: a cap member (9) covering a jetting portion jetting the ink of said recording head (5); a waste ink tank (13) collecting said waste ink; an ink suction pipe (10) joining said cap member (9) and said waste ink tank (13) for sucking and draining out waste ink adhering to said recording head (5); and a suction device (12) connected to said ink suction pipe (10); characterized in that said suction pipe (10) is provided with heating means for (14) heating said waste ink. The ink jet recording device according to claim 1, wherein the heating means (14) of said suction pipe (10) is provided with a heater line within said suction pipe (10). The ink jet recording device according to claim 1, wherein said suction pipe (10) is made of metal and is provided with said heating means (14) around outer circumference of said suction pipe (10). An ink jet recording device which performs recording by using a recording head (5) jetting ink to a recording medium (7), comprising: a cap member (9) covering a jet portion jetting the ink of said recording head (5); a waste ink tank (13) collecting said waste ink; an ink suction pipe (10) joining said cap member (9) and said waste ink tank (13) for sucking and draining out said waste ink adhering to said recording head (5); and a suction device (12) connected to said ink suction pipe (10); characterized in that said suction pump (12) has heating means (19) for heating said waste ink. The ink jet recording device according to claim 4, wherein said suction device (12) is a tube pump (12) including: a pipe member (10) at least part of which is formed of elastic body; and a pressurizing roller (16a, 16b, 16c) generating negative pressure in said pipe member (10) by pressurizing said pipe member (10) externally while moving the pressurized portions. The ink jet recording device according to claim 5, wherein said tube pump (12) has a ring-shaped heating means (19), a heat source of which is an infra-red lamp (20). An ink jet recording device according to claim 1 or 4, characterized by heating means (22, 23) provided at said carriage (3) for heating said cap member (9) while said carriage (3) is in contact with said cap member (9). The ink jet recording device according to claim 7, wherein said heating means (22, 23) includes a first heater (22) provided inside said ink tank (4) and a second heater (23) in direct contact with said recording head (5).

Inventors: KANAYAMA YOSHIO, KOYAMA KAZUYA, KUBOTA HIROSHI, OCHI NORIHIRO, TSURUI KOHJI, YOSHIMURA HISASHI, KANAYAMA, YOSHIO, KOYAMA, KAZUYA, KUBOTA, HIROSHI, OCHI, NORIHIRO, TSURUI, KOHJI, YOSHIMURA, HISASHI
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1995
Main classification: B41J2
IPC codes: B41J2