Sheet conveying means for a recording apparatus

Abstract: A recording apparatus comprises recording means (8) for recording an image on a sheet (3) positioned at a predetermined recording position, conveying means for conveying the sheet so that the latter passes through the recording position, and supporting means for supporting the conveying means in such a manner as to shift the conveying means in a first direction transverse to a sheet feeding direction and separating from the recording means (8) and then to shift the conveying means in a second direction same as the sheet feeding direction.

Description: The present invention relates to a recording apparatus such as a word processor, printer and the like, and more particularly, it relates to a recording apparatus according to the precharacterizing part of claim 1. Recently, in recording systems such as word processors, printers and the like, a recording apparatus wherein a recording medium is intermittently conveyed in a predetermined direction by a convey roller mechanism (conveying means) and an image is recorded on the recording medium by scanning a carriage mounting thereon an ink jet recording head (recording means) in a direction perpendicular to a recording medium feeding direction has been developed and practically used. For example, referring to an ink jet printer shown in Fig. 12, a recording sheet 80 is supplied in a direction shown by the arrow A by means of a sheet supply mechanism (not shown) and is fed between feed guides 82a, 82b supported by a bottom plate 81 of the printer. Then, the recording sheet 80 is fed until it reaches a nip between an auxiliary scanning roller 84a and an auxiliary scanning driven roller 84b supported by bearing portions 83a, 83b. Thereafter, by rotating the auxiliary scanning roller 84a and the auxiliary scanning driven roller 84b, the recording sheet 80 is directed to a nip between an ejector roller 87a and an ejector driven roller 87b supported between bearing portions 86a, 86b while being supported by a platen 85 secured to the bottom plate 81. The auxiliary scanning roller 84a and the ejector roller 87a are rotated by a driven force from a convey motor 88. The bearing portions 83a, 83b and the bearing portions 86a, 86b are formed on left and right side plates 95, 96 uprightly formed on the bottom plate 81, and the auxiliary scanning roller 84a and the auxiliary scanning driven roller 84b, and the ejector roller 87a and the ejector driven roller 87b are positioned by the side plates 95, 96. A recording head 90 mounted on a carriage 89 is disposed above the platen 85, and a timer belt 92 extending between motor pulleys 91a, 91b is connected to the carriage 89. The motor pulley 91a is driven by a main scanning motor 93 to reciprocally shift the carriage 89 along a main scanning rail (guide rail) 94. The recording head 90 has removable ink cartridges (black cartridge 90BK, cyan cartridge 90C, magenta cartridge 90M, yellow cartridge 90Y) including therein ink having four colors, and has a plurality of nozzles extending in directions perpendicular to a shifting direction of the carriage 89, so that the ink is discharged toward the platen 85 in response to image information. When the carriage 89 scans the recording sheet 80 supported by the platen 85 through the main scanning motor 93, the recording is effected by discharging the ink from the recording head. Whenever one-line recording is finished, the recording sheet 80 is fed by a predetermined amount in the direction A by driving the auxiliary scanning roller 84a and the ejector roller 87a. In the above-mentioned recording apparatus, when the recording sheet 80 is jammed by being caught by any constructural element of the apparatus during the feeding of the recording sheet, it is necessary to remove the jammed recording sheet 80. In the past, the jammed sheet was removed by retracting a sheet supply cassette (not shown) and then by pulling the jammed sheet by hand, or by lifting the auxiliary scanning driven roller 84b and the ejector driven roller 87b upwardly and then by inserting the hand from a downstream side of the sheet feeding direction between the auxiliary scanning roller 84a and the auxiliary scanning driven roller 84b or between the ejector roller 87a and the ejector driven roller 87b, thus removing the jammed recording sheet 80. However, in the above-mentioned jam treatments, there arose the following problems. That is to say, when the recording sheet 80 is jammed after it is supplied from the sheet supply cassette for a small distance, since the operator's hand inserted from the sheet ejecting direction does not reach the jammed recording sheet, the jammed sheet must be removed by retracting the sheet supply cassette from the recording apparatus; however, if did so, it was feared that a leading end of the jammed sheet was teared and remained in the apparatus, thus obstructing the further or next sheet supplying operation. Further, when the jam treatment is effected by inserting the operator's hand between the auxiliary scanning roller 84a and the auxiliary scanning driven roller 84b or between the ejector roller 87a and the ejector driven roller 87b, it was feared that the operator's finger(s) touched roller surface(s), thus smearing the latter, with the result that, during the next recording operation, the smudge was adhered to the recording sheet 80 to worsen the image quality. Further, since the auxiliary scanning roller 84a and the auxiliary scanning driven roller 84b, and the ejector roller 87a and the ejector driven roller 87b are positioned by the bearing portions 83a, 83b and the bearing portions 86a, 86b formed in the left and right side walls 95, 96 uprightly formed on the bottom plate 81, respectively, if the jam treatment was effected by lifting the auxiliary scanning driven roller 84b and the ejector driven roller 87b, it was feared that the positional accuracy of the conveying means with respect to the recording head 90 was changed after the jam treatment. In order to solve the above problems, it is necessary to provide various spaces in the apparatus for facilitating the insertion of the operator's hand; however, this results in the large-sized apparatus. Particularly, in a recording apparatus wherein the recording sheet 80 can be supplied from a plurality of overlapped sheet supply cassettes, since it is necessary to insert the operator's hand between the cassettes, it is feared that the efficiency of the spaces is reduced. Document US-A-4 431 180 discloses a generic recording apparatus according to the precharacterizing part of claim 1. This apparatus has a roller supporting arrangement comprising a plurality of pairs of copy paper transport rollers, wherein a support frame supporting a plurality of rollers is rotatable about a horizontal support shaft supported on the housing of said apparatus. In each pair of rollers, only one roller of the corresponding pair is shiftable. There is further provided a control lever pivotally supported on the housing, by means of which an associating shaft supporting the underface of an inclined surface of the support frame can be lowered to open the support frame when copy paper jamming has taken place. According to this arrangement, the supporting means for supporting the conveying means are operable to shift the above-mentioned shiftable rollers of the roller pairs in a direction transverse to the sheet feeding direction. The object of the present invention is to provide a recording apparatus, the construction of which makes the jam treatment easier and ensures the safety of the apparatus during the jam treatment. An aim of the present invention is to provide a recording apparatus which ensures the positional accuracy between a conveying means and a recording means after the jam treatment. The other aim of the present invention is to provide a recording apparatus which can improve the efficiency of spaces in the apparatus, thus making the apparatus small-sized. In the following the invention is further illustrated by embodiments with reference to the accompanying drawings. In the drawings: Fig. 1 is a perspective view showing a schematic construction of an ink jet printer; Fig. 2 is a perspective view of the ink jet printer for explaining the jam treatment operation; Fig. 3 is a sectional view of the ink jet printer looked at from a direction shown by the arrow G in Fig. 1; Figs. 4A to 4C are explanatory views for explaining a lifting movement of a chassis; Figs. 5A to 5C are explanatory views for explaining a lowering movement of the chassis; Fig. 6 is a plan view looked at from a direction shown by the arrow N in Fig. 4C; Fig. 7 is a plan view looked at from a direction shown by the arrow N in Fig. 5C, showing the chassis slightly retracted in a direction shown by the arrow K; Fig. 8 is a perspective view of an image recording apparatus according to a second embodiment of the present invention; Fig. 9 is a schematic view showing a recording portion; Fig. 10 is a perspective view of an image recording apparatus according to a third embodiment of the present invention; Fig. 11 is a schematic constructural view showing an image recording apparatus according to a fourth embodiment of the present invention; and Fig. 12 is a perspective view of a conventional recording apparatus. Now, the present invention will be explained with reference to the accompanying drawings, which is applied to a recording apparatus utilizing an ink jet recording system. In this embodiment, an ink jet printer is used as the recording apparatus. First of all, a schematic construction of the ink jet printer to which the present invention is applied will be explained with reference to Fig. 1. Incidentally, in the ink jet printer according to this embodiment, as shown in Fig. 3, the recording is effected on a recording sheet (recording medium) 3 which can be supplied from ovelapped cassettes 1, 2 serving as first and second containing means. In Fig. 1, a main scanning motor 4 secured to a chassis (not shown) serves to drive a carriage 5 in directions shown by the arrows B, C. A belt 6 extends between a pulley 5a secured to a motor shaft of the main scanning motor 4 and a pulley 5b rotatably supported on the chassis (not shown). A main scanning rail 7 acting as a guide rail is supported at its both ends by side walls (not shown) and bearing portions 5c of the carriage 5 are fitted on the rail with substantially no play. Further, a portion of the belt 6 is connected to a portion of the carriage 5, so that the carriage 5 can be reciprocally shifted in the directions B, C along the main scanning rail 7 via the belt 6 by rotating the main scanning motor 4. A recording head 8 constituting recording means is mounted on the carriage 5 and serves to form an image in response to image information. When energy is applied to the recording head 8 in response to a record signal, the recording head discharges ink from its discharge openings. In the illustrated embodiment, among ink jet recording systems, a system having a thermal energy generating means (for example, electrical/thermal converters, laser beams and the like) is particularly used for generating thermal energy as energy utilizing to discharge the ink, so that the change in ink condition is caused by such thermal energy. According to this system, high recording density and high recording fineness can be attained. Further, in this embodiment, the recording head 8 is provided with four ink cartridges having different color ink (cartridge 8BK for black ink, cartridge 8C for cyan ink, cartridge 8M for magenta ink, cartridge 8Y for yellow ink), and each ink cartridge is provided at its lower portion with an array of plural nozzles (not shown) each extending in a direction perpendicular to a shifting direction of the carriage 5, so that the ink can be discharged onto the recording sheet 3 moved on a platen 9 in a direction shown by the arrow A. The nozzles of the recording head 8 are disposed near the recording sheet 3 as long as possible, in order to improve the target accuracy of the discharged ink droplets onto the recording sheet 3, and are faced to the platen 9 between an auxiliary scanning driven roller 14b and an ejector driven roller 15b which constitutes a conveying means (described later). A recovery unit 10 serves to maintain the nozzles of the recording head 8 in the good condition when the carriage 5 is kept at a home position and to perform the recovery operation, and is supported by a bottom plate 11 while being regulated by the side wall (not shown) to which the main scanning rail 7 is attached. The reason why the recovery unit 10 is positioned by the side wall is that it is necessary to accurately align the nozzles of the recording head 8 with recovery openings of the recovery unit and that the accuracy of the relative position between the main scanning rail 7 for guiding the carriage 5 and the recovery unit 10 is improved. The recovery openings are formed in an upper surface of the recovery unit 10 so that they face the corresponding color nozzles (recovery opening 10BK for black color ink nozzles, recovery opening 10C for cyan color ink nozzles, recovery opening 10M for magenta color ink nozzles, recovery opening 10Y for yellow color ink nozzles). The reference numerals 11a and 11b denote sheet guides for guiding the recording sheet 3. The recording sheet 3 supplied between the sheet guides 11a, 11b from the cassette 1 is fed until a leading end of the recording sheet is abutted against a nip between an auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b which constitute the conveying means. The sheet guides 11a, 11b have both ends supported by levers 12, 13 which are rotatably received into bearing holes 12a, 13a, respectively, for pivotal movement in a direction shown by the arrow D in Fig. 3. The reference numerals 14a, 14b and 15a, 15b denotes the above-mentioned auxiliary scanning roller 14a and auxiliary scanning driven roller 14b which constitute the conveying means, and the ejector roller and ejector driven roller disposed in parallel with the scanning rollers. The auxiliary scanning roller 14a is rotatably supported in bearing portions 14c secured to both ends of a chassis 16 constituting supporting means, and the auxiliary scanning driven roller 14b is rotatably supported by one ends of levers 12, 13 and are pivoted around bearing holes 12a, 13a formed in support plates (not shown) attached to the chassis in the direction D in Fig. 3. Further, as shown in Fig. 3, the levers 12, 13 are provided with spring holder portions 12b, 13b and cam portions 12c, 13c, and tension springs 17 are connected between the spring holder portions 12b, 13b and the chassis. Thus, the auxiliary scanning driven roller 14b is urged against the auxiliary scanning roller 14a by elastic forces of the tension springs 17. Further, when the chassis 16 is lowered in a direction shown by the arrow I in Fig. 3 by means of an elevator mechanism (described later), the cam portions 12c, 13c are abutted against a cam portion 19a of a sheet guide 19 secured to a chassis 18 constituting further supporting means. When the chassis 16 is further lowered in the direction I in Fig. 3, the cam portions rotate the levers 12, 13 around the bearing holes 12a, 13a in the direction D in Fig. 3 in opposition to the elastic forces of the tension springs 17, thus slightly separating the auxiliary scanning driven roller 14b from the auxiliary scanning roller 14a. The reference numeral 20 denotes an auxiliary scanning pulley press-fitted on the auxiliary scanning roller 14a; and 21 denotes an ejector pulley press-fitted on the ejector roller 15a. These pulleys are connected to a motor pulley 24a of a convey motor (driving source) 24 via belts 22, 23, respectively. Further, both ends of the ejector driven roller 15b are rotatably supported by bent portions 26a of a lever 25. The lever 25 is rotatably mounted on the support plates (not shown) attached to the chassis 16 for pivotal movement around bearing holes 26b formed in the bent portions 26a in a direction shown by the arrow E in Fig. 3. Levers 27, 28 are attached to the bent portions 26a, respectively, which levers 27, 28 are provided with spring holder portions 27a, 28a and cam portions 27b, 27c, respectively. As shown in Fig. 3, tension springs 29 are connected between the spring holder portions 27a, 28a and the chassis 16, so that the ejector driven roller 15b is urged against the ejector roller 15a by tension forces of the tension springs 29. Further, when the chassis 16 is lowered in the direction I in Fig. 3 by means of the elevator mechanism (described later), the cam portion 27b of the levers 27 is abutted against a cam portion 30c of a bearing 30a secured to the chassis 18, and the cam portion 28b of the lever 28 is abutted against a cam portion 31a of an angle 31 secured to the chassis 18. When the chassis 16 is further lowered, the lever 25 is rotated around the bearing holes 26b in the direction E in Fig. 3 in opposition to the tension forces of the tension springs 29, thus slightly separating the ejector driven roller 15b from the ejector roller 15a. Further, although Fig. 3 shows a condition that the recording sheet 3 can be supplied from the upper and lower cassettes 1, 2, the recording sheets 3 are not supplied from both cassettes simultaneously. The reference numeral 32 denotes a partition plate for isolating the sheet supply cassettes 1, 2 from the conveying means for the recording sheet 3, which partition plate is secured to the bottom plate 11. The partition plate 32 is provided with windows 32a, 32b for permitting the passage of the recording sheets 3 supplied from the cassettes 1, 2, respectively. Further, the recording sheet 3 supplied from the cassette 2 is guided by a guide portion 19b of the sheet guide 19 shiftable together with the chassis 18 in a direction shown by the arrow K, and then is guided by a sheet guide 33 both ends of which are supported by the levers 12, 13, so that the recording sheet is directed between the auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b. Further, the reference numeral 61 denotes an ejection door constituting a part of an outer frame of the printer. The recording sheet 3 after recorded is ejected onto an ejection tray (not shown) attached to the ejection door 61 through the window 61a. The ejection door 61 is pivotally connected to the bottom plate 11 by means of hinges (not shown) for pivotal movement around holes 61b. In the recording condition, as shown in Fig. 3, an ejecting portion of the printer is closed, whereas, when the jam treatment is effected, the ejecting portion of the printer is opened so that the chassis 18 can be retracted. The recording sheet 3 supplied from either the cassette 1 or the cassette 2 by means of a sheet supply roller 1a or 1b is pinched between the auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b and is conveyed by them. When the leading end of the recording sheet 3 reaches a recording area of the platen 9, the auxiliary scanning roller 14a is stopped, and the carriage 5 is reciprocally shifted along the main scanning rail 7 in the direction perpendicular to the sheet feeding direction. While the carriage is being shifted, the four color inks are discharged from the recording head 8, thus recording an image on the recording sheet 3. The recording is effected by a predetermined length along the sheet feeding direction whenever the recording head 8 is scanned once, and, whenever the recording regarding each scanning operation is finished, the recording sheet is conveyed by a predetermined amount by means of the auxiliary scanning roller 14a. By alternatively repeating the recording of the predetermined length and the conveyance of the recording sheet of the predetermined length, it is possible to record the images through substantially the whole area of the recording sheet. The recording sheets having different sizes are loaded in the cassettes 1, 2. When the recording sheets are used up, the cassettes 1 or 2 are retracted in a direction opposite to a direction shown by the arrow G in Fig. 1, and new recording sheets are replenished therein. Thereafter, the cassette is inserted in the direction G. In Fig. 2, the reference numerals 34 and 35 denote slide rails supported by the bottom plate 11 via a supporting mechanism (not shown) and capable of permitting the shifting movement of the chassis 18 in directions shown by the arrows J and K. The slide rails 34, 35 are extended toward the cassettes 1, 2 through holes 32c, 32d formed in a partition plate 32, as shown in Fig. 3. If the lengths of the slide rails 34, 35 are selected so that they do not protrude toward the cassettes 1, 2, as shown in Fig. 3, a stroke for retracting the chassis 18 in the direction K for the jam treatment will be shorter or insufficient, thus making the jam treatment difficult. Further, if the slide rails 34, 35 are arranged outside the partition plate 32, front ends 34a, 35a of the rails will be protruded rightwardly (Fig. 3), thus making the apparatus large-sized. Thus, as mentioned above, rear ends 34b, 35b of the slide rails 34, 35 are extended toward the cassettes 1, 2. Further, regarding the heights of the slide rails 34, 35, as shown in Fig. 3, they are disposed between the upper cassette 1 and the lower cassette 2 for the following reasons. (1) Since it is necessary to provide sheet supply mechanisms (not shown) for supplying the recording sheets 3 from the cassettes 1, 2, and, particularly, since the sheet supply mechanism for the cassette 2 must be arranged between the cassettes 1 and 2, there is a space between the cassettes regardless the presence of the slide rails 34, 35. Accordingly, by arranging the slide rails in this space, the space can be utilized more effectively. (2) If the slide rails 34, 35 are arranged above the cassette 1, it is feared that they interfere with the scanning movement of the carriage 5. (3) If the slide rails 34, 35 are arranged at the same height as the cassette 1 or cassette 2, in order to avoid the interference with the cassettes, the slide rail 34 must be arranged at this side (Fig. 3) regarding the cassettes and the slide rail 35 must be arranged at the other side of the cassettes, with the result that the dimensions of the apparatus in the directions B and C in Fig. 1 will be increased. Further, when the mounting direction for the cassettes 1, 2 coincides with the direction G in Fig. 1, if the slide rails 34, 35 are arranged at the same height as the cassette 1 or cassette 2, cassettes 1, 2 cannot be inserted or retracted along such direction. Accordingly, by arranging the slide rails 34, 35 between the upper cassette 1 and the lower cassette 2, since the space obtained after the chassis 18 is retracted can be used as the space for the jam treatment, the space can be utilized more efficiently, thus permitting the compactness of the apparatus. Incidentally, in Figs. 1 and 2, the reference numerals 36, 37, 38 and 39 denote positioning plates constituting a positioning means when the chassis 16 is lifted (i.e., shifted in a direction shown by the arrow H in Fig. 3). The positioning plates 36, 38, 39 have downwardly (direction I in Fig. 3) directed positioning pins 36a, 38a, 39a, respectively. These positioning pins 36a, 38a, 39a are adapted to be received in holes formed in positioning guides 40, 41, 42 attached to the chassis 16, respectively. That is to say, the positioning pin 36a can be received in the hole 40a of the positioning guide 40, the positioning pin 38a can be received in the hole 41a (not shown) of the positioning guide 41, and the positioning pin 39a can be received in the hole 42a of the positioning guide 42. The fitting relation between the positioning pin 36a and the positioning hole 40a is selected to be relatively close; the fitting relation between the positioning pin 38a and the positioning hole 41a is selected to be close in the directions J, K and be loose in the directions B, C in Fig. 1; and the fitting relation between the positioning pin 39a and the positioning hole 42a is selected to be loose. By fitting the positioning pins into the corresponding positioning holes, the chassis 16 is positioned in the directions B, C in Fig. 1 and in the directions J, K in Fig. 3. Further, the positioning of the chassis 16 in the height direction (direction H in Fig. 3) is effected by abutting the guides 40, 41, 42 against the positioning plates 36, 38, 39, respectively, and by abutting the chassis 16 against the positioning plate 37. The positioning plates 36, 37 are secured to the side plate (not shown) to which the main scanning rail 7 is attached. With this arrangement, the relative positional accuracy between the positioning plates 36, 37 and the main scanning rail 7 can be maintained, thus improving the relative positional accuracy between the carriage 5, and the platen 9, auxiliary scanning roller 14a, auxiliary scanning driven roller 14b, ejector roller 15a and ejector driven roller 15b which are attached to the chassis 16, and improving the recording accuracy of the recording head 8 mounted on the carriage 5. Further, the positioning plates 38, 39 are integrally attached to the recovery unit 10 for the following reasons. (1) As mentioned above, it is necessary to maintain the relative positional accuracies between the recording head 8, recovery unit 10, platen 9, auxiliary scanning roller 14a and auxiliary scanning driven roller 14b, and ejector roller 15a and ejector driven roller 15b. To this end, the positioning plates 36, 37 are attached to the side plate (not shown) to which the main scanning rail 7 is secured, thus positioning the chassis 16 at its one side. Even when the positioning plates 38, 39 for positioning the chassis 16 at its other side are attached to the other side plate (near the recovery unit 10 in the direction B in Fig. 1), there is no problem regarding the accuracy. However, if the positioning plates 38, 39 are attached to the other side plate (not shown), the other side plate to which the main scanning rail 7 is attached is arranged between the chassis 16 and the recovery unit 10, which will interfere with the scanning movement of the carriage 5. Further, when the other side plate to which the main scanning rail 7 is secured is arranged at a position further spaced apart from the recovery unit 10 in the direction B in Fig. 1, the positioning plates 38, 39 are also further spaced apart from the recovery unit 10 in the direction B, thus interfering the chassis 16 with the recovery unit 10. (2) Since the recovery unit 10 is positioned by the other side plate (not shown) to which the main scanning rail 7 is secured, when the positioning plates 38, 39 are attached to the recovery unit 10, the relative positional accuracy between the recording head 8, recovery unit 10 and chassis 16 is not worsened. Incidentally, in this embodiment, while the positioning plates 38, 39 were attached to the recovery unit 10 as discrete parts, these positioning plates 38, 39 may be integrally formed with the recovery unit 10. Further, when the recovery unit 10 is supported by a member secured to the other side wall, the positioning plates 38, 39 may be secured to this member or may be integrally formed with this member. Next, a lifting/lowering movement of the chassis 16 looked at from a direction shown by the arrow G in Fig. 1 will be explained with reference to Figs. 4A to 4C and 5A to 5C. Fig. 4C shows the chassis 16 in a lifted position, and Fig. 5C shows the chassis 16 in a lowered position. Further, Figs. 4A and 4B show conditions that the chassis 16 is being lifted, and Figs. 5A and 5B show conditions that the chassis 16 is being lowered. Now, explaining an elevator mechanism for the chassis 16, as shown in Fig. 1, both end of a rotary shaft 30d are rotatably supported by bearings 30a, 30b, and levers 43a, 43b are pivotally mounted on the rotary shaft 30d. A grip 30e has both end secured to the levers 43a, 43b. Further, as shown in Fig. 4B, the levers 43a, 43b are provided with U-shaped recesses 43c, 43d. A slider 14 has elongated slots 44a, 44b, 44c formed therein and has a shaft 44d extending perpendicular to a plane of Fig. 4B. Rollers 45a, 45b are rotatably supported on the shaft 44d and are adapted to be received in the U-shaped recesses 43c, 43d of the levers 43a, 43b. The slider 44 is slidably supported by support plates 46a, 46b so that it can be shifted in the direction K in Fig. 4B or in the direction J in Fig. 5B along the elongated slots 44a, 44c. Incidentally, hereinbelow, the elevator mechanism for the chassis will be explained regarding the operation thereof effected by the support plate 46a, lever 43a and the like which are arranged this side as to Figures, and explanation of the support plate 46b, lever 43b and the like arranged at the other side will be omitted. As shown in Fig. 4B, pins 47, 48 are formed on a front (this side) surface of the support plate 46a, and, as shown in Fig. 4A, levers 49, 50 are rotatably mounted on the pins 47, 48. Rollers 49a, 50a are rotatably mounted on free ends of the levers 49, 50 and are received in elongated slots 51a, 51b formed in a support plate 51, thus supporting the support plate 51. Compression springs 52 rested on the support plate 51 are guided by pins 53 of the support plate 51 and serve to bias the chassis 16 upwardly. Fig. 4A shows a condition that the chassis 16 is lifted. In this condition, as shown in Fig. 1, the chassis 16 is positioned by the positioning plates 36, 37, 38, 39 in the height direction, and is urged against the positioning plates 36, 37, 38, 39 by compressing the compression springs 52, and thus, fixed with respect to these positioning plates. The reference numeral 54 denotes a shaft extending from the elevator mechanism regarding the front support plate 46a to the elevator mechanism regarding the rear support plate 46b. This shaft passes through the slot 44b (Fig. 4B) of the slider 44 and elongated slots 49b, 50b (Fig. 4A) of the levers 49, 50. Further, as shown in Fig. 4B, the support plate 46a is provided with a U-shaped notch 55 through which the shaft 54 passes for movement in an up-and-down direction along the notch. After the jam treatment is effected by retracting the chassis 16 from the apparatus, the chassis is re-inserted into the apparatus. Regarding this, a mechanism for preventing the chassis 16 from being lifted during the re-insertion of the chassis 16 into the apparatus is provided on the chassis 18. Now, this lift preventing mechanism will be explained with reference to Figs. 6 and 7. Similar to the above, the lift preventing mechanism adjacent to the elevator mechanism relating to the front support plate 46a, front lever 43a and the like will be explained, and the explanation of the other lift preventing mechanism arranged at the other side will be omitted. Fig. 6 is a view looked at from the direction N of Fig. 4C with omitting the chassis 16, pins 53, compression springs 52, support plate 51 and rollers 49a, 50a. Further, Fig. 7 is a view looked at from the direction N of Fig. 5C with being shifted in the direction K in Fig. 3 and omitting the chassis 16, pins 53, compression springs 52, support plate 51 and rollers 49a, 50a. In Fig. 6, a pawl portion 44e is formed on the slider 44 at a predetermined position by bending a portion of the slider, which pawl portion can be engaged by an engagement pawl portion 56a formed on a rock lever 56 by bending a portion of this lever forwardly. The rock lever 56 is provided with two slots 56b, a rearwardly bent spring holder portion 56c and an inclined surface 56d. By inserting two pins 57 formed on the rear surface of the chassis 18 into the slots 56b, the rock lever is supported for pivotal movement in directions shown by the arrows Q, R. A tension spring 58 is connected between the spring holder portion 56c of the rock lever 56 and a spring holder portion 18a formed on the chassis 18 by bending a portion of this chassis rearwardly, thus biasing the rock lever 56 toward the direction R. Further, the chassis 18 is provided with an aperture 18b through which the engagement pawl portion 56a of the rock lever 56 protrudes forwardly from the rear surface side of the chassis 18. An angle 59 is disposed in the vicinity of the rock lever 56, and a roller 60 is rotatably mounted on a shaft 59a secured to the angle 59. As shown in Fig. 6, in the condition that the rock lever 56 is biased toward the direction R, the roller 60 is engaged by the inclined surface 56d of the rock lever 56, thus shifting the rock lever 56 in the direction Q in opposition to a tension force of the tension spring 58. Next, a retracting and re-inserting operation of the conveying means of the printer as constructed above during the jam treatment will be explained. (Lowering movement) In Fig. 1, when the recording sheet 3 is jammed, an operator opens the ejection door 61 and shifts the carriage 5 onto the recovery unit 10 as shown by the two dot and chain line in Fig. 1. Then, the operator pulls the grip 30e in the direction L in Fig. 4B. Consequently, the levers 43a, 43b are rotated around the rotary shaft 30d, together with the U-shaped recesses 43c, 43d formed therein. Meanwhile, a rotational force is transmitted to the shaft 44d via the rollers 45a, 45d engaged by the recesses 43c, 43d, thus shifting the slider 44 in the direction K along the slots 44a, 44c. When the slider 44 is shifted in the direction K, the shaft 54 is lowered along the slot 44b. As shown in Fig. 4A, since the shaft 54 passes through the slots 49b, 50b of the levers 49, 50 the lever 49 is rotated around the pin 47 in a direction shown by the arrow P and the lever 50 is rotated around the pin 48 in a direction shown by the arrow S. Since the rollers 49a, 50a supported on the free ends of the levers 49, 50 are received in the slots 51a, 51b of the support plate 51, respectively, the rotation of the levers 49, 50 causes the support plate 51 to lower in the direction I in Fig. 4C, thus lowering the chassis 16 via the compression springs 52 (refer to Fig. 5C). (Releasing of recording sheet holding force) When the chassis 16 is lowered as mentioned above, the cam portions 12c, 13c (Fig. 3) of the levers 12, 13 are abutted against the cam portion 19a of the sheet guide 19, thus rotating the levers 12, 13 around the bearing holes 12a, 13a in the direction D in opposition to the tension forces of the tension springs 17. As a result, the auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b are shifted from the recording position holding the recording sheet 3 to a holding force releasing position where the auxiliary scanning roller 14a is slightly spaced apart from the auxiliary scanning driven roller 14b, thus releasing the holding force pinching the recording sheet 3. Further, when the chassis 16 is lowered, the cam portions 27b, 28b of the levers 27, 28 secured to the levers 25, 26 are abutted against the cam portion 30c of the bearings 30a, 30b and the cam portion 31a of the angle 31, respectively, thus rotating the levers 25, 26 around the bearing holes 26b in the direction E in opposition to the tension forces of the tension sprins 29, with the result that the ejector driven roller 15b held by the bent portions 25a, 26a of the levers 25, 26 is slightly separated from the ejector roller 15a. In this way, by shifting the ejector roller 15a and the ejector driven roller 15b from the recording position holding the recording sheet 3 to the holding force releasing position where the ejector roller 15a is slightly spaced apart from the ejector driven roller 15b, thus releasing the holding force pinching the recording sheet 3. (Retracting movement) When the holding forces between the rollers constituting the conveying means for the recording sheet 3 are released as mentioned above, as shown in Fig. 5B, by pulling the grip 30e in the direction L, a lock mechanism (not shown) for the chassis 18 is released, and the chassis 18 can be shifted in the direction K. Such lock mechanism may be constituted by a conventional mechanism utilizing an inversion spring. Thus, the whole conveying means for the recording sheet 3 can be retracted from the printer to a jam treatment position. (Jam treatment) When the conveying means is retracted from the printer, since a large space is created in the printer, the operator can insert his hand into this space and can take the jammed recording sheet 3 out. Although the recording sheet 3 may be jammed at various locations in the printer, for example, even if the recording sheet 3 is jammed as shown by the two dot and chain line in Fig. 2 after it is supplied from the cassette 1 or 2 for a small distance, it is possible to remove the jammed recording sheet 3 without trouble. Further, even when the recording sheet 3 is jammed with being pinched between the auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b or between the ejector roller 15a and the ejector driven roller 15b, since the holding forces for the recording sheet 3 are released in the conveying means, it is possible to easily remove the jammed recording sheet 3. For example, when the recording sheet 3 is jammed in a condition that a trailing end portion of such recording sheet is largely remained in the cassette, since a leading end portion of such recording sheet is depended in the space (created by retracting the conveying means) in the printer, the operator can easily remove such jammed recording sheet by hand. Further, when the trailing end portion of the recording sheet 3 supplied from the cassette is jammed between the auxiliary scanning roller 14a and the auxiliary scanning driven roller 14b or between the ejector roller 15a and the ejector driven roller 15b, since the jammed recording sheet 3 is retracted together with the conveying means out of the printer, the recording sheet can easily be removed by pulling it in the direction T or U in Fig. 2. (Re-inserting movement) When the jam treatment is finished, the operator re-inserts the conveying means via the grip 30e from the position of Fig. 2 in the direction J until the lock mechanism for the chassis 18 in the printer starts to operate. In this point, the grip 30e and the levers 43a, 43b are positioned at locations 30e', 43a', 43b', respectively, shown by the two dot and chain line in Fig. 3. Thereafter, the grip 30e' is further inserted into the position 30e to lift the conveying means. However, when the grip 30e is positioned at the location 30e', the operator sometimes closes the ejection door 61 erroneously. To avoid such inconvenience, in the illustrated embodiment, it is so designed that, when the grip 30e and the levers 43a, 43b are positioned at the locations 30e', 43a', 43b', even if the operator tries to close the ejection door 61, the latter cannot be closed by interfering it with the grip 30e' and the levers 43a', 43b'. Further, in the illustrated embodiment, the opening/closing movement of the ejection door 61 is detected by a switch (not shown) so that the carriage 5 cannot be shifted so long as the ejection door 61 is opened. That is to say, only when the conveying means is returned to the recording position, the ejection door 61 can be closed and the carriage 5 becomes the operative condition. Thus, so long as the conveying means is lowered, the carriage 5 cannot operate. In this way, it is possible to prevent the carriage 5 from dropping on the lowered platen 9, thus preventing the damage of the nozzles of the recording head 8 and ensuring the safety of the apparatus. (Lift preventing operation) When the conveying means is positioned at the recording position in the printer, as shown in Fig. 6, the rock lever 56 is biased toward the direction R by the tension force of the tension spring 58 so that the inclined surface 56d is abutted against the roller 60. From this condition, when the operator pulls the grip 30e (Fig. 1) in the direction L in Fig. 4B, the slider-44 is shifted in the direction K as mentioned above. When the grip 30e is further pulled, the lock mechanism (not shown) which has holded the chassis 18 at the position of Fig. 6 is released, with the result that the chassis 18 is shifted in the direction K in Fig. 6 to reach a condition shown in Fig. 7. In Fig. 7, since the inclined surface 56d of the rock lever 56 is separated from the roller 60, the rock lever 56 is shifted in the direction R, and the engagement pawl portion 56a reaches behind an engagement end portion 44f of the slider 44 which has already been shifted in the direction K. As a result, the movement of the slider 44 in the direction J is prevented. In this condition, the jam treatment is effected by further retracting the chassis 18 in the direction K. After the jam treatment, the chassis 18 is shifted in the direction J by pushing the grip 30e in the direction M. However, in this case, as mentioned above, since the slider 44 cannot be shifted in the direction J, the chassis 16 cannot be lifted to the original position. When the chassis 18 is shifted in the direction J, the lock mechanism (not shown) operates to lock the position of the chassis 18, and the inclined surface 56d of the rock lever 56 is abutted against the roller 60, thus shifting the rock lever 56 in the direction Q in opposition to the tension force of the tension spring 58. Consequently, the engagement pawl portion 56a is separated from the end 44f of the slider 44, with the result that the slider 44 can be shifted in the diretion J. In this condition, when the grip 30e is further pushed in the direction M, the slider 44 is shifted in the direction J to shift the chassis 18. When the chassis 18 is shifted up to the holding force releasing position, the chassis 16 is lifted. Incidentally, in the illustrated embodiment, even if the chassis 16 is lifted in the condition that the conveying means has been retracted from the printer, as shown in Fig. 2, since the chassis 16 is interfered with the positioning plate 37, the chassis cannot be inserted into the printer. (Lifting movement) As mentioned above, when the grip 30e is rotated in the direction M, the driving force is transmitted reversely in the case of the lowering movement of the chassis 16, thus shifting the slider 44 in the direction J. Consequently, as shown in Fig. 4B, the shaft 54 is lifted while being guided by the slot 44b to lift the support plate 51 via the levers 49, 50, thus lifting the chassis 16. In this case, the chassis 16 is firmly positioned by the fitted engagements between the positioning pins 36a, 38a, 39a of the positioning plates 36, 38, 39 and the guides 40, 41, 42 and by the abutment between the positioning plate 37 and the chassis 16 by the urging forces of the compression springs 52. Thus, it is possible to position the conveying means at the recording position safely and correctly. In the illustrated embodiment, while the ink jet recording system was used as the recording means, a recording means may preferably be designed so that electrical/thermal converters are energized in response to the recording signal, and the ink is discharged from the discharge opening by growing a bubble in the ink by the heat exceeding the film boiling generated by the energization of the electrical/thermal converter. Preferably, the typical construction and principle thereof can be realized by using the fundamental principles, for example, disclosed in U.S. Patent Nos. 4,723,129 and 4,740,796. Although this system can be applied to both a so-called "on-demand type" and "continuous type", it is more effective when the present invention is particularly applied to the on-demand type, because, by applying at least one drive signal corresponding to the record information and capable of providing the abrupt temperature increase exceeding the nucleate boiling to the electrical/thermal converters arranged in correspondence to the sheet or liquid passages including the liquid (ink) therein, it is possible to form a bubble in the liquid (ink) in corresponding to the drive signal by generating the film boiling on the heat acting surface of the recording head due to the generation of the thermal energy in the electrical/thermal converting elements. Due to the growth and contraction of the bubble, the liquid (ink) is discharged from the discharge opening to form atleast one ink droplet. When the drive signal has a pulse shape, since the growth and contraction of the bubble can be quickly effected, more excellent ink discharge is achieved. Such pulse-shaped drive signal may be ones disclosed in U.S. Patent Nos. 4,463,359 and 4,345,262. Incidentally, by adopting the condition disclosed in U.S. Patent No. 4,313,124 providing the invention regarding the temperature increasing rate on the heat acting surface, a further excellent recording can be performed. As the construction of the recording head, the present invention includes the construction wherein the heat acting portion is disposed in an arcuate area as disclosed in U.S. Patent Nos. 4,558,333 and 4,459,600, as well as the constructions wherein the discharge openings, liquid paths and electrical/thermal converters are combined (straight liquid paths or orthogonal liquid paths) as disclosed in the above U.S. Patents. In addition, the present invention can applicable to the construction wherein each discharge opening is constituted by a slit with which a plurality of electrical/thermal converters associated in common as disclosed in the Japanese Patent Laid-Open No. 59-123670 and the construction wherein openings for absorbing the pressure wave of the thermal energy are arranged in correspondence to the discharge openings as disclosed in the Japanese Patent Laid-Open No. 59-138461, because the recording can be correctly and effectively performed regardless of the configuration of the recording head. Further, among the above-mentioned recording heads of serial type, a recording head secured to the carriage or a removable recording head of chip type wherein, when mounted on the carriage, electrical connection between it and the recording apparatus and the supply of ink from the recording apparatus can be permitted, as well as a recording head of cartridge type wherein a cartridge is integrally formed with the head may be used. Further, it is preferable that a head recovering means and an auxiliary aiding means are added to the recording head according to the present invention, since the effect of the present invention is further improved. More concretely, these means include a capping means for capping the recording head, cleaning means, pressurizing or suction means, and an auxiliary heating means comprising electrical/thermal converters or other heating elements or the combination thereof. Further, it is effective for the stable recording to perform an auxiliary discharge mode wherein the ink discharge regardless of the recording ink discharge is effected. Further, as to the kind and number of the recording head to be mounted on the carriage, each recording head may correspond to each different color ink, or a plurality of recording heads can be used for a plurality of ink having different colors and/or different density. That is to say, for example, as the recording mode of the recording apparatus, the present invention can effectively be applied not only to a recording mode with a single main color such as black, but also to system providing a plurality of different colors and/or a full-color by mixing colors by using an integrated recording head or the combination of plural recording heads. Further, in the illustrated embodiments, while the ink was liquid, the ink may be solidified in a room temperature or less and be softened or liquidized at a room temperature. In the ink jet recording system, since the temperature control is generally effected in a temperatuare range from 30 °C to 70 °C so that the viscosity of the ink is maintained within a stable discharging range, the ink may be liquidized when the record signal is emitted. In addition, ink having a feature that is firstly liquidized by the thermal energy, such as solid ink which serves to prevent the increase in temperature by absorbing energy in changing the ink from the solid state to the liquid state or which is in the solid state in the preserved condition to prevent the vaporization of ink and which is liquidized into ink liquid to be discharged in response to the record signal comprising the thermal energy, or ink which has already been solidified upon reaching the recording medium, can also be applied to the present invention. In such a case, the ink can be held in the liquid state or solid state in recesses or holes in porous sheet as disclosed in the Japanese Patent Laid-Open Nos. 54-56847 and 60-71260, in confronting relation to the electrical/thermal converters. Further, the above-mentioned ink jet recording apparatus may be in the form of a recording apparatus used as an image outputting terminal equipment of an information processing system such as a computer, or a copying machine combined with a reader, or a facsimile system having the communication ability. Next, a second embodiment of the present invention will be explained with reference to Figs. 8 and 9. Incidentally, Fig. 8 is a perspective view of a main portion of an image recording apparatus and Fig. 9 is a schematic elevational sectional view of a main portion of the image recording apparatus. In this embodiment, at a recording station, a recording sheet is intermittently fed in a predetermined direction by means of a convey roller mechanism, and an ink jet mechanism acting as a recording means is scanned in a direction perpendicular to a sheet feeding direction. An auxiliary scanning roller 113 and an auxiliary scanning driven roller 114 are rotatably supported at their both ends by bearing portions 131, 132 secured to a base 125, so that a recording sheet 101 advancing from a direction shown by the arrow A can be fed to the right by the rotation of these rollers. A platen 119 for supporting the fed recording sheet 101 is secured to the base 125 at a downstream of the auxiliary scanning roller 113 in the sheet feeding direction. Further, an ejector roller 120 and an ejector driven roller 121 urged against the ejector roller 120 are disposed at a downstream side of the platen 119 in the sheet feeding direction. The ejector roller 120 and the ejector driven roller 121 are rotatably supported at their both ends by bearing portions 133, 134 secured to the base 125. Since the bearing portions for the rollers are supported by the same base 125, the heights of a contacting portion between the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114 and a contacting portion between the ejector roller 120 and the ejector driven roller 121 can be regulated with high accuracy, and the parallelism between these contacting portions can also be regulated with high accuracy. An upper guide 111 and a lower guide 112 supported by the base 125 serve to direct the recording sheet 101 to the contacing portion (nip) between the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114. Since these guides are supported by the same base 125 as that for the bearing portion 131 of the auxiliary scanning roller 113, the positional relation between the guides and the the auxiliary scanning roller can be regulated with high accuracy. An ejection guide 124 serves to guide the recording sheet 101 fed by the ejector roller 120 and the ejector driven roller 121 out of the apparatus 201. An auxiliary scanning pulley 115 is secured to a left (Fig. 8) end of the auxiliary scanning roller 120, and, similarly, an ejector pulley 122 is secured to a left end of the ejector roller 120. On the other hand, at a left lower portion of the base 125, a convey motor 117 is secured to the base 125 via a motor holding bracket 126. A convey motor pulley 118 is secured to a rotary shaft of the convey motor 117, which convey motor pulley can transmit a rotational driving force to the auxiliary scanning pulley 115 and the ejector pulley 122 via an auxiliary scanning belt 116 and an ejector belt 123. In this case, a diameter of the ejector pulley 122 is so selected that a convey speed of the ejector roller 120 becomes slightly faster than that of the auxiliary scanning roller 113. Further, since a pinching force of the nip between the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114 is selected to be greater than that of a pinching force of the nip between the ejector roller 120 and the ejector driven roller 121, a feeding amount of the recording sheet 101 is defined by the auxiliary scanning roller 113, thus preventing the recording sheet 101 from being slacked on the platen 119. A main scanning rail 106 extending in parallel with an axial direction of the auxiliary scanning roller 113 is secured to the apparatus 201 above the platen 119 at the left side thereof. A carriage 107 has a bearing portion 107A slidably fitted on the main scanning rail 106 so that the carriage can be shifted in an axial direction (shown by the arrows B and C in Fig. 8) of the main scanning rail 106. A main scanning motor 102 is disposed above the main scanning rail 106 at the left side thereof and is secured to a side wall of the apparatus 201. A main scanning motor pulley 103 is secured to a rotary shaft of the main scanning motor 102 to rotate together with the rotary shaft. An idler pulley 105 is rotatably supported by the side wall of the apparatus 201 at a position corresponding to the main scanning pulley 103 and spaced apart from the latter in the direction B in Fig. 8. A main scanning belt 104 extends between the main scanning motor pulley 103 and the idler pulley 105 and turns in synchronous with the rotation of the main scanning motor 102. Between the pulleys 103, 105, the main scanning belt 104 is connected to the carriage 107, so that the carriage 107 can be shifted in the direction B or C by the rotation of the main scanning motor 102. A roller 107B (Fig. 9) is rotatably mounted on a lower portion of the carriage 107, which roller can keep a distance between the carriage 107 and the recording sheet 101 constant by rolling on the recording sheet 101 supported on the platen. Four ink cartridges including different color inks are secured to the carriage 107 at predetermined positions. The ink cartridge for black color ink is designated by 108BK, the ink cartridge for cyan color ink is designated by 108C, the ink cartridge for magenta color ink is designated by 108M, and the ink cartridge for yellow color ink is designated by 108Y. As shown in Fig. 9, an ink jet head 108A comprising a plurality of nozzles arranged in a direction perpendicular to a shifting direction of the carriage 107 and a mechanism for applying ink discharging forces to the nozzles is disposed on the bottom of each ink cartridge in confronting relation to the platen 119. Each ink jet head 108A can discharge ink in the corresponding ink cartridge as ink dots toward the recording sheet 101 supported on the platen 119. The ink jet head 108A can utilize various ink discharging energy generating means. In the illustrated embodiment, each ink jet head 108A has a thermal energy generating means (for example, electrical/thermal converters or laser beams and the like) which generates the thermal energy to cause the change in the ink state or condition. According to this system, it is possible to attain the high density and high fineness of the recording. When the carriage 107 and the ink cartridges 108Y, 108M, 108C, 108BK are in a non-operative condition (non-recording condition), the carriage 107 can be shifted to a position (shown by the solid line in Fig. 8) out of a recording area together with the ink cartridges 108Y, 108M, 108C, 108BK under the control of the main scanning motor 102. When the carriage 107 is situated in this position, in order to prevent the jamming of the nozzles due to the drying of ink therein, cap portions 110Y, 110M, 110C, 110BK for sealing the nozzles in the corresponding ink jet head 108A to keep the interior of the nozzles in a wetted condition are arranged on the base 125. Further, a recovery unit 109 for recovering the abnormity in the ink discharge due to the unnecessary bubbles and (or) foreign matters generated in the nozzles is arranged on the base 125 behind the ink cartridges 108Y, 108M, 108C, 108BK. The recovery unit 109 includes therein a suction pump for reducing the pressures in the cap portions 110Y, 110M, 110C, 110BK, sucking the unnecessary bubbles and (or) foregin matters in the nozzles together with the ink and removing them from the nozzles. The suction pump has a mechanism for converting the rotational driving force into a negative pressure, and thus, the pump can be driven by the rotational driving force from the auxiliary scanning roller 113 via gears 141, 142. Telescopic slide rails 135, 136 are attached at their one ends to the ejection end of the apparatus 201 at both left and right sides (looked at from the ejection side) between upper and lower cassettes 141' and 142' each containing the recording sheets. On the other hand, engagement holes 143, 144 are formed in the other end of the slide rail 135, and engagement holes (not shown) are formed in the other end of the slide rail 136 in correspondence to the engagement holes 143, 144. Further, engagement pins 147, 148 engaged by the engagement holes 143, 144 and engagement pins engaged by the engagement holes of the slide rail 136 are formed on a lower portion of the base 125 at its both sides. Thus, the base 125 can be shifted in response to the sliding movements of the slide rails 135, 136. The base 125 to which the upper guide 111, lower guide 112, ejection guide 124, bearing portions (131, 132, 133, 134), platen 119, convey motor 117 and recovery unit 109 are secured is supported by these two slide rails 135, 136 so that it can be retracted in the ejection direction via a grip 137. After retraction, by disengaging the engagement pins 147, 148 and the like from the corresponding engagement holes 143, 144 and the like, the base 125 can be detached from the slide rails. A recording operation is as follows. The recording sheet 101 is supplied from the cassette 141' or 142' by means of a sheet supply roller 141a or 142a and is fed in the direction A, and is inserted between the upper and lower guides 111, 112 secured to the base 125. Then, the recording sheet 101 is guided by the guides 111, 112 to reach the nip between the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114. Since the positional relation between the guides 111, 112 and the rollers 113, 114 is regulated with high accuracy, the recording sheet 101 can reach the nip correctly. By drive-controlling the convey motor 117, the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114 are rotated, thus feeding the recording sheet onto the platen 119 and then feeding it to the nip between the ejector roller 120 and the ejector driven roller 121. In this point, the convey motor is stopped temporarily. Since the heights of the nip between the auxiliary scanning roller 113 and the auxiliary scanning driven roller 114, an upper surface, and the nip between the ejector roller 120 and the ejector driven roller 121 are regulated with high accuracy, and the parallelism between the nip regarding the auxiliary scanning roller 113 and the nip regarding the ejector roller 120 is also regulated with high accuracy, the recording sheet 101 is subjected to uniform feeding direction and convey speed in its widthwise direction, thus being fed properly. Accordingly, the recording sheet 101 is not slacked on the platen 119, thus avoiding the poor sheet feeding. Then, the main scanning motor 103 is activated to shift the carriage 107 in the direction C in Fig. 8. During this shifting movement of the carriage, ink discharge signals corresponding to the image information are sent from a control portion of the apparatus to the ink jet heads 108A of the ink cartridges 108Y, 108M, 108C, 108BK, thus discharging the ink dots on the recording sheet 101 supported on the platen 119 to form an image of a predetermined width on the recording sheet. Thereafter, the main scanning motor 102 is rotated reversely to shift the carriage 107 in the direction B out of the recording area. After this, by repeating the intermittent feeding operations of the recording sheet 101, the scanning movements of the carriage 107 and the ink discharging operations of the ink jet heads 108A, the two-dimensional image is obtained. In assembling main elements relating the conveying or feeding of the recording sheet at the recording station, after these elements have previously been assembled on the base 125, the base 125 is pushed and slid via the grip 137 until a rear surface of the base 125 is abutted against stopper plates 127, 128, thus positioning the base. In this case, the relative positional relation between the main elements of the conveying means remains as it is (on the base 125). If the recording sheet 101 is jammed in the vicinity of the recording station, by pulling or retracting the base 125 via the grip 137, since the jammed recording sheet is also retracted together with the base, the jammed sheet can easily be removed. In this embodiment, since the convey motor 117 and the drive force transmitting system are constituted integrally with the auxiliary scanning roller 113 and the ejector roller 120, there is no change in the tension forces even when the auxiliary scanning belt 116 and the ejector belt 123 are exchanged or dismounted and re-mounted, thus ensuring the stability of the driving response. Accordingly, the constant feeding amount of the sheet can be obtained, thus improving the image quality. Fig. 10 shows a third embodiment of the present invention. In this embodiment, a recording means for forming an image on the recording sheet at a recording station and a conveying means for affording a predetermined feeding amount to the recording sheet can bodily be mounted and dismounted with respect to the recording apparatus. Since the conveying means may be the same as that of the above-mentioned first embodiment, the explanation thereof will be omitted. A right side plate 151 and a left side plate 152 each having a vertical surface perpendicular to a main plane of a base 125 are secured to right and left sides of the base 125, while keeping the positional relation between these plates with high accuracy. A main scanning rail 106 extending in parallel with an axial direction of an auxiliary scanning roller 113 is disposed above a platen 119 at the left side thereof, and both ends of the rail are supported by the right and left side plates 151, 152. A carriage 107 has a bearing portion 107A slidably fitted on the main scanning rail 106 so that the carriage can be shifted in an axial direction (shown by the arrows B and C) of the main scanning rail 106. A main scanning motor 102 is disposed above the main scanning rail 106 at the left end thereof, and a main scanning motor pulley 103 is secured to a rotary shaft of the motor to rotate together with the rotary shaft. An idler pulley 105 is rotatably supported by the right side wall 151 at a position corresponding to the main scanning motor pulley and spaced apart from the latter in the direction B. A main scanning belt 104 extends between the main scanning motor pulley 103 and the idler pulley 105 and turns in synchronous with the rotation of the main scanning motor 102. Between these pulleys, a portion of the main scanning belt 104 is connected to a rear surface of the carriage 107, so that the carriage 107 can be shifted in the direction B or C by the rotation of the main scanning motor 102. The internal construction of the carriage 107 and the construction of ink cartridges 108 mounted thereon are the same as those of the above-mentioned first embodiment. A flat cable 153 for transmitting the ink discharge signals from the control portion of the apparatus to ink jet heads is disposed behind the carriage 107, and a cable supporting portion 154 for supporting the flat cable is integrally supported by the carriage 107. The flat cable 153 includes a curved portion 153A having an appropriate slack to compensate for the change in distance between the carriage 107 and the control portion of the apparatus during the scanning movement of the carriage 107 or when the carriage is dismounted from the apparatus. The positional relation of cap portions 110Y, 110M, 110C, 110BK and recovery unit 109 is the same as that of the first embodiment. Axially telescopic slide rails 135, 136 are secured to left and right lower portions of the base 125. The other ends of the slide rails 135, 136 are supported by the apparatus. The right and left side plates 151, 152 have bent walls 151A, 152A directing toward the interior of the apparatus, respectively, and positioning pins 155, 156 protruding toward the interior of the apparatus are secured to the bent walls. On the other hand, a fitting plate 164 having a positioning hole 163 adapted to receive the positioning pin 156 is secured to a left side wall 161 of the apparatus. Similarly, a fitting plate 166 having a positioning hole 165 adapted to receive the positioning pin 155 is secured to a right side wall 162 of the apparatus. A grip 137 is secured to a front surface of the base 125 to be moved together with the base 125. In assembling, after the various elements have previously been assembled on the base 125, the operator pushes or inserts the base 125 into the apparatus via the grip 137, thus sliding the base 125 along the slide rails 135, 136. As a result, the base is positioned in the direction B, C by fitting the positioning pins 155, 156 into the positioning holes 163, 165 and is also positioned in the direction A, D by abutting the bent walls 151A, 152A against the fitting plates 164, 166. If the maintenance and (or) inspection is desired, by performing the above-mentioned operations reversely, the recording system can be dismounted from the apparatus. With the arrangement as mentioned above, since the main scanning system and the auxiliary scanning system are integrally constructed, it is possible to stabilize the conveying means and to obtain the positional relation between the recording means and the conveying means with high accuracy. Accordingly, since the parallelism between the scanning trace plane for the ink jet heads 108A and the upper surface of the platen 119 and the proper distance between them can be ensured, it is possible to minimize the change in the direction of the discharging ink, thus improving the accuracy of the target points of the ink dots on the recording sheet 101. Further, since the perpendicularity between the main scanning direction and the auxiliary scanning direction can easily be maintained, the perpendicularity between the recording sheet 101 and the image is also improved. Fig. 11 is a sectional view showing a fourth embodiment of the present invention wherein a conveying means can be mounted and dismounted with respect to the apparatus by rotating the former, and only shows main elements. A carriage 173 is slidably supported by a main scanning rail 171 passing through the carriage. The carriage is also supported on an auxiliary rail 172 via a roller 175 rotatably mounted on the carriage, so that the carriage can be shifted along an axial direction of the main scanning rail 172. The carriage 173 incorporates therein ink tanks which can discharge ink dots toward a platen 179 through corresponding left ink jet heads 174 in response to the discharge signals supplied from the control portion of the apparatus. Inner and outer sheet supply guides 175, 176 serve to guide the recording sheet 101 supplied from below toward a direction shown by the arrow E to a recording station. At the recording station, there is arranged a supersonic vibration conveying means 177 having a supersonic vibrator and adapted to receive a drive signal from the control portion of the apparatus to apply the vibration from the supersonic vibrator to the recording sheet 101 as a uni-directional advancing wave, which supersonic vibration conveying means can be contacted with the recording sheet 101. In this way, the recording sheet 101 can be moved upwardly. An urging member 178 serves to effectively contact the recording sheet 101 with the supersonic vibration conveying means 177. When the ink is discharged from the ink jet head 174, the platen 179 supports the back surface of the recording sheet 101 to ensure the flatness of the sheet. A plurality of fine suction openings 184 are formed in the platen 179, which openings are connected to a vaccum pump 182 via a tube 183. The vacuum pump 182 operates to generate the negative pressure (with respect to the atmosphere) and serves to such the recording sheet 101 toward the platen 179 (when the recording sheet 101 is positioned on the platen 179), thus ensuring the flatness of the recording sheet. Inner and outer ejection guides 180, 181 serve to guide the recorded sheet from the recording station to ejector rollers 184, 185 in a direction shown by the arrow F. The outer sheet supply guide 176, supersonic vibration conveying means 177, platen 179 and outer ejection guide 181 are integrally assembled on a rotatable base 186 which can be rotated around a pivot pin 187 in directions G and H to be dismounted and mounted with respect to the apparatus 210. With this arrangement, since a sheet feeding path for the recording sheet 101 is divided (into two) in a direction perpendicular to the trace plane of the feeding movement of the recording sheet 101 in response to the dismounting operation of the conveying means, only by dismounting the conveying means, the position of the recording sheet 101 can easily be ascertained and the operator's finger can easily be inserted, thus removing the jammed recording sheet 101 easily.

Claims: A recording apparatus comprising: recording means (8) for recording an image on a sheet (3) positioned at a predetermined recording position; and conveying means (14a, 14b; 15a, 15b) for conveying the sheet in a sheet feeding direction so that the sheet passes through said recording position; characterized by supporting means (25, 26, 16, 49, 50, 54, 44, 44d, 43a-43d, 30e) for supporting said conveying means (14a, 14b; 15a, 15b) in such a manner as to shift said conveying means in a first direction (N) transverse to said sheet feeding direction, thereby separating said conveying means away from said recording means (8), wherein said conveying means has a pair of rollers ( 14a, 14b; 15a, 15b) for nipping the sheet therebetween, said paired rollers being additionaly separated from each other associated with the shift of said conveying means, and then to shift said conveying means in a second direction (K) being the same as the sheet feeding direction. A recording apparatus according to claim 1, further comprising: first and second containing means (1, 2) for containing sheets, respectively; first and second sheet supplying means (1a, 1b) for feeding out the sheets from said first and second containing means, respectively; and, further supporting means (18, 34, 35) for supporting said conveying means (14a, 14b; 15a, 15b) in such a manner as to shift said conveying means in a second direction being the same as a sheet feeding direction, said supporting means having at least a portion (34, 35) disposed between said first and second containing means (1, 2). A recording apparatus according to claim 2, wherein said containing means (1,2) can be shifted in a direction transverse to the sheet feeding direction. A recording apparatus according to claim 1 or 2, wherein said recording means (8) has an ink jet head for discharging ink. A recording apparatus according to claim 4, wherein said ink jet head discharges the ink by utilizing thermal energy. A recording apparatus according to claim 2, wherein said supporting means (34,35) has guide rail means for slidably supporting said conveying means (14a,14b,15a,15b). A recording apparatus according to claim 6, wherein said guide rail means (34,35) are disposed between said first and second containing means (1,2). A recording apparatus according to claim 1, further including separating means (27b,28b,30c) for separating said pair of rollers (15a,15b) from each other when said conveying means is shifted in said first direction (N). A recording apparatus according to claim 1, wherein said conveying means (14a, 14b; 15a, 15b) are arranged below said recording means, and said supporting means support said conveying means so that said conveying means can be shifted horizontally after said conveying means is shifted downwardly. A recording apparatus according to claim 1, further including preventing means (56a,44f) for preventing said conveying means (14a,14b;15a,15b) from shifting in a direction opposite to said first direction (N) when said conveying means is not positioned at a predetermined position where said conveying means faces said recording means (8).

Inventors: ADACHI SEIICHIRO, ARIGA KAZUTO, MATSUZAWA KUNIHIKO, UEHARA TSUKASA, YOSHINAGA KENJI, ADACHI, SEIICHIRO, ARIGA, KAZUTO, MATSUZAWA, KUNIHIKO, UEHARA, TSUKASA, YOSHINAGA, KENJI, Adachi, Seiichiro, c/o Canon Kabushiki Kaisha, Ariga, Kazuto, c/o Canon Kabushiki Kaisha, Matsuzawa, Kunihiko, c/o Canon Kabushiki Kaisha, UEHARA, TSUKASA, C/O CANON KABUSHIKI KAISHA, Yoshinaga, Kenji, c/o Canon Kabushiki Kaisha
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1992
Main classification: B41J13
IPC codes: B41J13