Image recording apparatus and recording-material feeding method

A feeder is provided inside an exposure section of a photographic printer. First and second feed-roller pairs are respectively disposed at an upstream side and a downstream side of an exposing position of the feeder. A first nip roller of the first feed-roller pair and a second nip roller of the second feed-roller pair are movable between a nip position for nipping paper sheets, and a release position for releasing the nip thereof. The second nip roller is moved to the nip position after an anterior end of the paper sheet situated at the most upstream side has passed the second nip roller. The first nip roller is moved to the release position before a posterior end of the paper sheet situated at the most downstream side leaves the first nip roller.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for feeding cut-sheet-shaped recording materials carried in parallel, and further relates to an image recording apparatus applying this feeding method.

2. Description of the Related Art

For example, in a photographic printer, an image is recorded by so-called scanning exposure. In this photographic printer, while a photosensitive material of a cut-sheet shape is nipped and fed in a sub-scanning direction by using a plurality of feed-rollers, recording light is scanned in a scanning direction perpendicular to the sub-scanning direction. In order to improve processing ability (number) of unit time, it is performed by preference that the photosensitive materials having an identical size or different sizes are arranged in the scanning direction and are simultaneously exposed (see Japanese Patent Laid-Open Publication No. 08-314022).

It is necessary for obtaining a high-quality photo print that the photosensitive material is accurately fed at the time of scanning exposure. When an anterior end of the photosensitive material butts against a feed-roller pair and a posterior end thereof leaves from the feed-roller pair, load fluctuation is caused by a shock at that time. Due to this, scanning unevenness occurs so that the quality of the photo print remarkably deteriorates. In view of this, such as described in Japanese Patent Laid-Open Publication No. 11-046262, when the anterior end of the photosensitive material reaches the feed-roller pair disposed at a downstream side of an exposure position, a nip state of this feed-roller pair is released. The photosensitive material is nipped after the anterior end thereof has passed the rollers of the feed-roller pair. And then, before the posterior end of the photosensitive material leaves from another feed-roller pair, which is disposed at an upstream side of the exposure position, the nip of this feed-roller pair is released. Mean while, in a case the photosensitive materials fed in parallel are simultaneously exposed, the feed-roller pairs are disposed in parallel, such as described in Japanese Patent Laid-Open Publication No. 2003-241321. These feed-roller pairs are individually changed between the nip state and the release state in accordance with sizes and so forth of the photosensitive materials of the respective rows. Thus, it is possible to prevent the scanning unevenness from occurring even when the photosensitive materials fed in parallel are simultaneously exposed.

By disposing the feed-roller pairs in parallel so as to correspond to the respective rows of the photosensitive materials such as described in the above Publication No. 2003-241321, the scanning unevenness of the entire rows seems to be prevented from occurring. However, since the feed-roller pairs are independently changed between the nip state and the release state, a mechanism thereof becomes complicated. Moreover, when sizes (length in the feed direction) of the photosensitive materials arranged in the scanning direction are different and when positions of the anterior ends are staggered, it is necessary to change nip timing and release timing relative to the photosensitive materials of the adjacent rows. Thus, control becomes complicated. Further, when the nip timing and the release timing of the adjacent feed-roller pairs are different, load fluctuation is caused. As a result, scanning unevenness occurs relative to the adjacent rows. In addition, when the photosensitive material has a wide width so as to overlap with the plural feed-roller pairs, load fluctuation is caused in case the nip timing and the release timing are not properly set relative to the adjacent feed-roller pairs. In this case, the scanning unevenness is likely to occur.

SUMMARY OF THE INVENTION

In view of the foregoing, it is a primary object of the present invention to provide an image recording apparatus and a recording-material feeding method, in which it is prevented without complicating a mechanism and control that scanning unevenness occurs at the time of simultaneous exposure.

In order to achieve the above and other objects, the image recording apparatus according to the present invention comprises a first feed-roller pair and a second feed-roller pair, which are respectively disposed at an upstream side and a downstream side of a record position of a sheet-shaped recording material in a feed direction thereof. While the feed-roller pairs move the recording materials in parallel, an image is recorded at the record position. The image recoding apparatus further comprises a changing mechanism, a detector and a controller. The changing mechanism changes the first and second feed-roller pairs between a nip state for nipping and feeding the recording material and one of a release state and a weak nip state. In the release state, the recording material is released. In the weak nip state, the recording material is nipped by a nipping force being weaker in comparison with the nip state. The detector detects passing of the recording material in each row. The controller controls the changing mechanism on the basis of a detection result of the detector so as to change the second feed-roller pair to the nip state after a lastly detected anterior end of the recording materials fed by the first-roller pair in parallel has passed through the second feed-roller pair kept in one of the release state and the weak nip state.

Moreover, the controller controls the changing mechanism on the basis of the detection result of the detector so as to change the first feed-roller pair to one of the release state and the weak nip state before a firstly detected posterior end of the recording materials fed by the first feed-roller pair in parallel leaves the first feed-roller pair kept in the nip state.

In a preferred embodiment, each of the feed-roller pairs are constituted of a drive roller, which is rotated by a motor, and a movable roller moving between a nip position for nipping the recording material with the drive roller and a release position for releasing the nip of the recording material. A position adjuster adjusts positions of the recording materials in a width direction thereof such that most outside lateral sides of the recording materials fed in parallel are situated so as to be substantially symmetrical about a center line of a balance of nipping by the movable rollers.

Further, it is preferable that the image recording apparatus further comprises a carrying guide, first press rollers and second press rollers. The carrying guide supports the recording materials fed in parallel. The first press roller presses the recording material against the carrying guide between the first feed-roller pair and the record position. The second press roller presses the recording material against the carrying guide between the record position and the second feed-roller pair. The changing mechanism changes the first and second press rollers between a press state for pressing the recording material and a press-releasing state for releasing the press of the recording material. The controller controls the changing mechanism on the basis of the detection result of the detector so as to change the second press roller to the press state after the lastly detected anterior end of the recording materials fed by the first-roller pair in parallel has passed through the second press roller kept in the press-releasing state. In addition, the controller controls the changing mechanism on the basis of the detection result of the detector so as to change the first press roller to the press-releasing state before the firstly detected posterior end of the recording materials leaves the first press roller kept in the press state.

Further, it is preferable that the controller controls the changing mechanism so as to stagger two image recording positions of the recording material to be recorded at the record position. At one of the image recording positions, the image is recorded when the first feed-roller pair kept in the nip state is changed to one of the release state and the weak nip state. At the other of the image recording positions, the image is recorded when the first press roller kept in the press state is changed to the press-releasing state.

Further, it is preferable that the controller controls the changing mechanism so as to stagger two image recording positions of the recording material to be recorded at the record position. At one of the image recording positions, the image is recorded when the second feed-roller pair kept in one of the release state and the weak nip state is changed to the nip state. At the other of the image recording positions, the image is recorded when the second press roller kept in the press-releasing state is changed to the press state.

The detector may include sensors for single-row use, which are disposed for the respective rows of the recording materials fed in parallel. Alternatively, the detector may be a line-shaped sensor capable of detecting passing of the recording materials, which are fed in parallel, at the respective rows thereof.

The recording-material feeding method for the image recording apparatus comprises the step of recording the images at the record position while the recording materials are fed by the first and second feed-roller pairs in parallel. The recording-material feeding method further comprises the steps of detecting the passing of the recording materials fed in parallel, and changing the second feed-roller pair to the nip state on the basis of the detection result of the passing. The second feed-roller pair is changed to the nip state after the lastly detected anterior end of the recording materials fed by the first roller pair in parallel has passed through the second feed-roller pair kept in one of the release state and the weak nip state.

Moreover, the recording-material feeding method further comprises the step of changing the first feed-roller pair to one of the release state and the weak nip state on the basis of the detection result before the firstly detected posterior end of the recording materials fed by the first feed-roller pair in parallel leaves the first feed-roller pair kept in the nip state.

In the image recording apparatus according to the present invention, it is unnecessary to independently nip and release the recording materials at the respective rows. As a result, it is possible without complicating a structure to prevent scanning unevenness from occurring at the time of simultaneous exposure of the recording materials. Moreover, it is possible to prevent the scanning unevenness from occurring due to slight vibration to be caused on the adjacent row at the time of nipping and releasing. Thus, control may be easily conducted. As a result, manufacturing cost of the apparatus may be held down.

Since the position adjuster is provide, it is possible to take the balance of nipping by adjusting the positions of the recording materials in a scanning direction even when the recording materials fed in parallel have different widths.

The image recording positions of the recording material are adapted to be staggered so that the roller causing the scanning unevenness is easily identified.

By the recording-material feeding method according to the present invention, it is similarly possible without complicating the structure to prevent the scanning unevenness from occurring at the time of the simultaneous exposure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 1is a schematic illustration showing a photographic printer10according to the present invention. In this printer10, cut-sheet-shaped photosensitive materials of two rows are fed and simultaneously exposed. The exposed photosensitive material is outputted as a photo print. As shown inFIG. 1, the photographic printer10is constituted of magazines12and13, cutters15and16, a back-printing unit18, an exposure section20, a processing unit22, and so forth.

The magazines12and13are set to magazine stands25and26vertically disposed in parallel. Each of the magazines25and26contains a recording-paper roll29formed by rolling a strip of a photosensitive recording paper28being as a photosensitive material. A paper roller pair30is disposed near a paper mouth of the respective magazines12and13. Upon rotating the paper roller pair30by means of a motor, which is not shown, the recording paper28is drawn out of the recording-paper roll29and is advanced to the respective cutters15and16.

The cutters15and16are respectively disposed so as to nip a passage of the recording paper28. When an anterior end of the recording paper28is advanced from the cutter by a predetermined length, a cutter driving mechanism not shown is actuated to cut the recoding paper28into a paper sheet31(seeFIG. 2) having the predetermined length. By the way, instead of providing two cutters, a single cutter may be disposed near the back-printing unit18.

The magazine stands25and26are respectively fixed to magazine-stand moving mechanisms32and33. As shown inFIG. 2, the magazine-stand moving mechanisms32and33respectively slide the magazine stands25and26in a scanning direction perpendicular to a feeding direction (sub-scanning direction). Incidentally, moving the magazine stands25and26with the mechanisms32and33is performed by utilizing belt drive, screw drive, rack-and-pinion drive and so forth. In virtue of this, positions of the paper sheets31aand31bto be advanced from the respective magazines12and13can be adjusted in a width direction of the paper sheet (in the scanning direction). Thus, it is possible to forward the paper sheets31aand31bhaving any widths, into the passage.

As shown inFIG. 1, the paper sheets31aand31badvanced from the magazines12and13are carried by a plurality of carrying roller pairs35and36disposed at the passages. The paper sheets31aand31bare carried along the passages shown by dashed lines in the drawing to pass through the back-printing unit18, the exposure section20and the processing unit22in this order. On this occasion, timing for advancing the paper sheets31aand31bfrom the respective magazines12and13toward the passages is adjusted beforehand so as to carry the paper sheets31aand31bfrom the respective magazines12and13in parallel. The back-printing unit18prints necessary information of film ID, a frame number and so forth on rear surfaces of the paper sheets31aand31b(surfaces opposite to recording surface).

The paper sheets31aand31bfor which back printing has been performed are carried in parallel toward the exposure section20after a skew of the paper sheet has been corrected as need arises. The exposure section20is constituted of an exposing unit38and a feeder39. The exposing unit38comprises a laser printer and an image memory, which are well known. The image memory stores image data read by a film scanner not shown. Alternatively, the image memory stores image data outputted from a recording medium of a memory card or the like. The laser printer scans recording light (laser beam), intensity of which is modulated in accordance with an image to be recorded, in the scanning direction perpendicular to the feeding direction (sub-scanning direction) to simultaneously print the images on the paper sheets31aand31bof two rows. Although the feeder39is described later in detail, nip states of the paper sheets31aand31bare changed in accordance with feed positions of the paper sheets31aand31bto reduce load fluctuation during scanning exposure. The exposed paper sheets31aand31bare forwarded to the processing unit22wherein various processes of coloring/developing, fixing and washing are executed. In the processing unit22, a drying process is further executed. And then, the paper sheet is discharged to the outside of the photographic printer10as a photo print.

Next, the feeder39is described below withFIGS. 3 and 4.FIG. 3is a top view of the feeder39andFIG. 4is a side view thereof. As shown inFIGS. 3 and 4, the feeder39comprises a first feed-roller pair43and a second feed-roller pair44, which are respectively disposed at an upstream side and a downstream side of an exposing position41where scanning exposure is performed by the exposing unit38.

The first feed-roller pair43is constituted of a first capstan roller45, which is rotated by a motor not shown, and a first nip roller46being as a driven roller. The respective rollers45and46are disposed so as to nip a guide plate48supporting the paper sheets31aand31b. Incidentally, the first capstan roller45corresponds to a first drive roller of the present invention, and the first nip roller46corresponds to a first movable roller of the present invention. As to the first capstan roller45and the first nip roller46currently used, rubber rolls45band46bare respectively fixed to rotary shafts45aand46aby a number (two) of the rows of the paper sheets31aand31b. In this embodiment, the rubber rolls46b(also the rubber rolls45b) of which the number is two are disposed at positions to press central areas of the paper sheets31aand31b. However, this is not exclusive. The number of the rubber rolls may be three or more on condition that the paper sheets31aand31bare pressed in balance. In another way, the paper sheets31aand31bmay be pressed by a single rubber roll having a sufficient length.

The second feed-roller pair44has a structure identical with that of the first feed-roller pair43, and is constituted of a second capstan roller49and a second nip roller50. Incidentally, the second capstan roller49corresponds to a second drive roller of the present invention, and the second nip roller50corresponds to a second movable roller of the present invention. As to the second capstan roller49and the second nip roller50currently used, rubber rolls49band50bare respectively fixed to rotary shafts49aand50aby a number (two) of the rows of the paper sheets31aand31b. Meanwhile, a belt not shown is laid between the first capstan roller45and the second capstan roller49so that these rollers are rotated at identical peripheral velocity by the same motor (not shown).

In case the paper sheets31aand31bfed in parallel are biased toward one end of the first nip roller46(the second nip roller50), a balance of nipping deteriorates so that an advancement amount of the paper sheet is likely to fluctuate. Moreover, in this case, since an edge of the paper sheet in a width direction is nipped, a skew is likely to be caused. In view of this, the magazine-stand moving mechanisms32and33are actuated to move the magazines12and13in the scanning direction such that outermost side edges of the paper sheets31aand31bexisting in the passage become substantially symmetrical about a center line C1of the balance of nipping in the scanning direction of the first nip roller46(second nip roller50), such as shown inFIG. 5Awhich is a schematic illustration viewed in an X-direction inFIG. 4(structure is partially abbreviated in the drawing). In other words, the magazine-stand moving mechanisms32and33are actuated to move the magazines12and13in the scanning direction such that a length L1extending from one side of the paper sheets31aand31bto the center line C1of the balance of nipping is substantially equal to a length L2extending from the other side of the paper sheets31aand31bto the center line C1. Meanwhile, such as shown inFIG. 5B, when the paper sheets31aand31bhave different widths, the magazine-stand moving mechanisms32and33are actuated such that a length L3extending from one side of the paper sheets31aand31bto the center line C1of the balance of nipping is substantially equal to a length L4extending from the other side of the paper sheets31aand31bto the center line C1. It is possible to adjust the positions of the respective paper sheets31aand31bin the scanning direction to strike the balance of nipping.

As shown inFIGS. 3 and 4, the first and second feed-roller pairs43and44respectively nip and release the paper sheets31aand31bby vertically moving the first and second nip rollers46and50in the drawing. In this embodiment, a cam unit,52is used as a mechanism for moving the first and second nip rollers46and50. By rotating the cam unit52, the first and second nip rollers46and50are moved between a nip position where the paper sheets31aand31bare nipped, and a release position where the nip state is released.

The cam unit52is constituted of a drive cam53, a first cam54and a second cam55. Incidentally, the respective cams53,54and55are arranged in an axis direction of the first and second nip rollers46and50. Two pulleys56and57are provided to rotate the drive cam53, and a timing belt58is laid between these pulleys and the drive cam53. Further, a motor59is connected to the pulley56. Upon rotating the pulley56by the motor59, the drive cam53is rotated via the timing belt58to rotate the first cam54and the second cam55.

In order to move the first and second nip rollers46and50between the nip position and the release position by utilizing the rotations of the first cam54and the second cam55, brackets61and62are provided so as to rotatably support the first and second nip rollers46and50. The brackets61and62are rotatably attached to rotary shafts64and65fixed to side plates66a(seeFIG. 3, not shown inFIG. 4) forming a frame66(seeFIG. 4) of the feeder39. The rotary shafts64and65are parallel with the axial direction of the first and second nip rollers46and50. Lateral sides of the brackets61and62are respectively provided with cam followers67and68to abut on the peripheries of the first and second cams54and55. The cam followers67and68are respectively urged toward the peripheries of the first and second cams54and55by means of springs69disposed between the frame66and the brackets61and62. Thus, by rotating the first and second cams54and55, the cam followers67and68are swung so that the brackets61and62are also swung around the rotary shafts64and65. Consequently, the first and second nip rollers46and50are moved between the nip position and the release position.

In this embodiment, the brackets61and62are formed from a metal rigid material of aluminum, for example, so as to rotatably support the first and second nip rollers46and50via bearings61aand62a(seeFIG. 3). First pressing mechanisms70and second pressing mechanisms71are respectively attached to the insides of the brackets61and62two by two. The pressing mechanisms70and71press the paper sheets31aand31bagainst the guide plate48to prevent anterior portions and posterior portions of the paper sheets31aand31bfrom levitating at the exposing position41. The first pressing mechanisms70press the paper sheets31aand31bbetween the exposing position41and the first feed-roller pair43. The second pressing mechanisms71press the paper sheets31aand31bbetween the exposing position41and the second feed-roller pair44.

The first and second pressing mechanisms70and71are constituted of arm members72, a first press roller73and a second press roller74. The arm member72has a plate shape, and the rollers73and74are rotatably attached to top ends of the arm members72. The other ends of the arm members72are rotatably attached to the brackets61and62(seeFIG. 4). A spring mechanism75(not shown inFIG. 3) comprising a spring and a shaft is attached to a central portion of the arm member72. The other ends of the spring mechanisms75are attached to the insides of the brackets61and62. The spring mechanism75is shrunk at the time of pressing. As a shrinkage amount of the spring mechanism75changes, a pressing force of the press roller pressing the paper sheet also changes. For example, the shrinkage amount of the spring is reduced as the bracket61rotates in a counterclockwise direction in the drawing to move the first nip roller46from the nip position to the release position. In association with this, the pressing force of the first press roller73is reduced. Incidentally, although illustration is abbreviated, a stopper is formed on the bracket to maintain an attachment angle of the arm member72within a predetermined range relative to the bracket. The stopper abuts on the bottom of the arm member72to prevent further rotation of the arm member72, for example. Meanwhile, attachment positions of the first and second press rollers73and74are not limited to the positions existing between the rubber rolls46band50bof the first and second nip rollers46and50such as shown inFIG. 4. Many rollers may be arranged at a downstream side of the rubber roll46band at an upstream side of the rubber roll50b. The number of the rollers may be increased and decreased as need arises in accordance with stiffness of the paper sheet31, on condition that the anterior end and the posterior end of the paper sheet are prevented from levitating. Further, the attachment positions of the rollers may be optionally determined.

The first and second press rollers73and74are moved among a press position, a provisional press position and a release position by utilizing the rotation of the cam unit52similarly to the first and second nip rollers46and50. In the press position, the paper sheets31aand31bare pressed. In the provisional press position, the paper sheets31aand31bare pressed by a weak pressing force. In the release position, pressing the paper sheet is released. The provisional press position is located between the press position and the release position. In the provisional press position, the paper sheets31aand31bare weakly pressed against the guide plate48only by the first and second press rollers73and74.

Pulleys78and79having the same diameter are respectively attached to lateral sides of the first and second nip rollers46and50. An extensible flat belt80is laid between the pulleys78and79. Thus, when one of the first nip roller46and the second nip roller50is rotated, the other nip roller is rotated in the same direction and at the same velocity. In virtue of this, when either of the nip rollers is rotated in the direction for advancing the paper sheets31aand31b, it is possible to nip and release the paper sheets31aand31bin a state that the other nip roller is rotated in the same direction and at the same velocity. As a result, shock is reduced at the time of nipping and releasing so that it is possible to prevent scanning unevenness from occurring.

The first and second nip rollers46and50are different from rollers described in the above-mentioned Publication No. 2003-241321. In the present invention, in order to simultaneously nip and release the paper sheets31aand31bfed in parallel, the second nip roller50and the second press roller74are moved to the nip position and the press position respectively after the anterior end of either of the paper sheets31aand31b, which is situated at the upstream side in the feed direction of the paper sheet, has passed through the second nip roller50and the second press roller74. Further, in the present invention, the first nip roller43and the first press roller73are moved to the release position and the press releasing position respectively before the posterior end of either of the paper sheets31aand31b, which is situated at the downstream side in the feeding direction, leaves the first nip roller43and the first press roller73.

For the purpose of detecting the anterior ends and the posterior ends of the paper sheets31aand31bfed in parallel, photo sensors82aand82bare disposed at an upstream side of the bracket61so as to correspond to the respective rows. Moreover, photo sensors83aand83bfor commencing image recording are disposed between the bracket61and the exposing position41so as to correspond to the respective rows. Each of the photo sensors82a,82b,83aand83bcomprises a light emitting element and a light receiving element, which are arranged so as to nip the passage of the paper sheets31aand31b. A detection signal of each photo sensor is sent to a controller85of the photographic printer10. The controller85controls each section of the photographic printer10to track the positions of the paper sheets31aand31bon the basis of the detection signals outputted from the photo sensors82aand82b, and information concerning a feed speed of the paper sheets31aand31b. Further, on the basis of the detection signals outputted from the photo sensors83aand83b, the exposing unit38commences scanning exposure. By the way, in this embodiment, the photo sensors83aand83bare provided in consideration of the misalignment of the paper sheets31aand31bto occur at the time of passing the first feed roller pair43. However, when the misalignment hardly occurs, only the photo sensors82aand82bmay be provided, and the photo sensors83aand83bmay be omitted. Moreover, in this embodiment, the photo sensors82a,82b,83aand83bare provided for the respective rows. Instead of this, a photo sensor having a line shape (line sensor) may be provided.

The controller85is connected to the photo sensors82a,82b,83aand83b, the motor59and so forth. When the anterior ends and the posterior ends of the paper sheets31aand31bare carried to the respective rollers, the controller85drives the motor59on the basis of the tracking result of the paper sheets31aand31bto rotate the cam unit52. Upon rotation of the cam unit52, the first and second nip rollers46and50are respectively moved to the release position, the nip position and the release position in this cyclic order. At the same time, the respective first and second press rollers73and74are also moved to the press releasing position, the provisional press position, the press position, the provisional press position and the release position in this cyclic order. While the respective paper sheets31aand31bpass through the feeder39, positional combinations of the rollers are set in six ways, which are described later in detail. Shapes and sizes of the first and second cams54and55are adjusted such that the respective rollers are moved in six ways during one rotation of the cam unit52.

A rotational velocity for rotating the cam unit52, namely a moving velocity of each of the rollers46,50,73and74is set to a low velocity so as to prevent the scanning unevenness from occurring on the paper sheets31aand31bdue to vibration, which is caused especially when the second nip roller50is moved from the release position to the nip position and the first nip roller46is moved from the nip position to the release position. The rotation of the cam unit52may be commenced before the anterior ends and the posterior ends of the paper sheets31aand31bpass the corresponding rollers46,50,73and74. In particular, when the first nip roller46is moved from the nip position to the release position, the rotation of the cam unit52may be commenced at the moment that a predetermined period has passed after detecting the transit of the corresponding posterior end by the photo sensors82aand82b.

In this embodiment, a press-starting position of the second press roller74and a nip-starting position of the second nip roller50are determined such that two image-exposure positions of the paper sheets31aand31bto be exposed at the exposing position41are staggered. When the paper sheets31aand31bare nipped by the second nip roller50(second feed-roller pair44), the paper sheets31aand31bare exposed at one of the image-exposure positions. When the paper sheets31aand31bare pressed by the second press roller74, the paper sheets31aand31bare exposed at the other of the image-exposure positions. On the basis of the determined starting positions for pressing and nipping, are adjusted the rotation of the cam unit52and the rotational velocity thereof. In virtue of this, when scanning unevenness has occurred, it is possible to specify the roller having a cause of the scanning unevenness (seeFIG. 14), such as described later in detail.

For the same purpose, a nip-terminating position of the first nip roller46and a press-terminating position of the first press roller73are determined such that two image-exposure positions of the paper sheets31aand31bto be exposed at the exposing position41are staggered (seeFIG. 14). When the paper sheets31aand31bare released from being nipped by the first nip roller46(first feed-roller pair43), the paper sheets31aand31bare exposed at one of the image-exposure positions. When the paper sheets31aand31bare released from being pressed by the first press roller73, the paper sheets31aand31bare exposed at the other of the image-exposure positions.

Next, an operation of the photographic printer10having the above structure is described below withFIGS. 1,3to13. Incidentally,FIGS. 6,8,10and12are schematic views illustrated by simplifyingFIG. 4, andFIGS. 7,9,11and13are schematic views illustrated by simplifyingFIG. 3. In association with a print instruction performed by a user, the photosensitive recording papers28are advanced from the recording-paper rolls29of the respective magazines15and16, and the cutters15and16cut the recording papers28into the paper sheets31aand31bhaving the predetermined length, such as shown inFIG. 1. Moreover, the magazine-stand moving mechanisms32and33are actuated to adjust the positions of the magazines12and13in the scanning direction in accordance with the width of the recording-paper roll29. The paper sheets31aand31badvanced from the respective magazines12and13are forwarded in parallel to the back-printing unit18by the carrying roller pairs35and36. In the back-printing unit18, the necessary information of the film ID, the frame number and so forth are printed.

The paper sheets31aand31bfor which back printing has been performed are forwarded in parallel to the feeder39of the exposure section20after the skew has been corrected as need arises. Before the paper sheets31aand31bare forwarded, an initial state is set such as shown inFIGS. 6 and 7. In the initial state, the first and second nip rollers46and50are kept in the release position, and the first and second press rollers73and74are kept in the press releasing position (the first combination).

As shown inFIGS. 8 and 9, when the paper sheets31aand31bare forwarded in parallel to the feeder39, either of the anterior ends thereof is detected by the photo sensors82aand82b. At this time, the controller85drives the motor59to rotate the cam unit52so that the first nip roller46and the first press roller73are respectively moved toward the nip position and the press position (the second combination). By the way, in this embodiment, the paper sheets31aand31bhave the same size, and the paper sheet31bis ahead rather than the paper sheet31a. The first nip roller46commences to rotate after moving to the nip position. Upon this, the second nip roller50also commences to rotate at the same velocity by means of the pulleys78,79and the flat belt80.

The paper sheets31aand31bpass the first nip roller46and the anterior ends thereof pass the photo sensors83aand83b. The controller85activates the exposing unit38on the basis of the detection signal, which is outputted from the photo sensors83aand83b, and the feed-speed information of the paper sheets31aand31bto commence the scanning exposure for the paper sheets31aand31b. Further, the controller85tracks the position of the paper sheet31aon the basis of the detection signals of the photo sensors82a,82band the carrying-speed information of the paper sheets31aand31b. At this time, passing of the anterior end of the paper sheet31ais lastly detected. After the anterior end of the paper sheet31ahas passed the second press roller74, the cam unit52is rotated to move the second press roller74to the provisional press position (the third combination).

Successively, the paper sheet31apasses through the second feed-roller pair44. After that, the cam unit52is rotated to move the second press roller74to the press position, and at the same time, the second nip roller50is moved to the nip position such as shown inFIGS. 10 and 11(the fourth combination). Incidentally, the second nip roller50moves to the nip position, rotating in the feed direction of the paper sheets31aand31b, so that a shock is reduced at the time of nipping.

The posterior ends of the respective paper sheets31aand31bpass the photo sensors82aand82b. After that, the controller85tracks the position of the paper sheet31bon the basis of the detection signal, which is outputted from the photo sensors82aand82b, and the feed-speed information of the paper sheets31aand31b. In this embodiment, the posterior end of the paper sheet31bis detected first. Before the posterior end of the paper sheet31bleaves the first feed-roller pair43, the cam unit52is rotated to move the first nip roller46to the release position, and at the same time, the first press roller73is moved to the provisional press position such as shown inFIGS. 12 and 13(the fifth combination). Incidentally, since the second nip roller50rotates, the first nip roller46rotates at the same velocity therewith, and in this state, the first nip roller46is moved to the release position. Thus, a shock is reduced at the time of releasing the nip. And then, before the posterior end of the paper sheet31bleaves the first press roller73, the cam unit52is rotated to move the first press roller73to the press releasing position (the sixth combination).

After the scanning exposure for the paper sheets31aand31bhas been completed and all the paper sheets31aand31bhave passed through the second feed-roller pair44, the cam unit52is rotated to the position of the initial state to move the second nip roller50and the second press roller74to the release position and the press releasing position respectively. The above-described processing is repeated when the next paper sheets31aand31bare forwarded to the feeder39. The shapes, the sizes and so forth of the first and second cams54and55are adjusted so as to move the respective rollers46,50,73and74in the turn of the above-mentioned six combinations. By merely adjusting the first and second cams54and56, it is possible to prevent the scanning unevenness from occurring even if the paper sheets31aand31bfed in parallel have different sizes, especially have different lengths in the feed direction, and even if the anterior ends of the paper sheets are staggered.

For example, when the anterior ends of the paper sheets31aand31bhaving the same size are staggered (the paper sheet31bis ahead) such as shown inFIG. 14, the press-starting position of the second press roller74(A1line in the drawing) and the nip-starting position of the second nip roller50(B1line in the drawing) are determined on the basis of the position of the anterior end of the paper sheet31abeing behind. In addition, the nip-terminating position of the first nip roller46(B2line in the drawing) and the press-terminating position of the first press roller73(A2line in the drawing) are determined on the basis of the position of the posterior end of the paper sheet31bbeing ahead.

At this time, the press-starting position (A1line) and the nip-starting position (B1line) are determined such that the image-exposure positions (EA1line and EB1line) are staggered. The image-exposure position of the EA1line is exposed when the second press roller74has just pressed the paper sheets31aand31b. The image-exposure position of the EB1line is exposed when the second feed-roller pair44has just nipped the paper sheets31aand31b. Moreover, the nip-terminating position (B2line) and the press-terminating position (A2line) are determined such that the image-exposure positions (EB2line and EA2line) are staggered. The image-exposure position of the EB2line is exposed when the first feed-roller pair43has just released the nip. The image-exposure position of the EA2line is exposed when the first press roller73has just released the press. Hereinafter, reasons for staggering the image-exposure positions are concretely described below.

A shift length Δd of the paper sheets31aand31bare substantially constant unless a kind, a size and so forth of the paper sheets are changed. The Δd may be obtained in advance by experiment and may be obtained on the basis of time-difference information of the paper sheets31aand31bhaving passed the photo sensors82aand82b. When the Δd is constant, the press-starting position A1of the second press roller74is located at a constant position separating from the anterior end of the paper sheet31aby a length L5. Moreover, the nip-starting position B1of the second nip roller50(second feed-roller pair44) is located at a constant position separating from the anterior end of the paper sheets31aby a length L6. Further, the nip-terminating position B2of the first nip roller46(first feed-roller pair43) and the press-terminating position A2of the first press roller73are respectively located at constant positions separating from the posterior end of the paper sheet31bby the lengths L6and L5.

In this case, when lengths from the exposing position41to the first and second press rollers73and74are represented as L7, the image-exposure position EA1is situated at an upstream side of the press-starting position A1by the length L7. Incidentally, the image-exposure position EA1is exposed when the second press rollers74have started to press the paper sheets31aand31b. Meanwhile, the image-exposure position EA2is situated at a downstream side of the press-terminating position A2by the length L7. Incidentally, the image-exposure position EA2is exposed when the first press rollers73have just released the paper sheets31aand31b. Meanwhile, when lengths from the exposing position41to the first and second nip rollers46and50are represented as L8, the image-exposure position EB1is situated at an upstream side of the nip-starting position B1by the length L8. The image-exposure position EB1is exposed when the second nip roller50has started the nip. Moreover, the image-exposure position EB2is situated at a downstream side of the nip-terminating position B2by the length L8. The image-exposure position EB2is exposed when the first nip roller46has terminated the nip.

The respective image-exposure positions EA1, EA2, EB1and EB2of the paper sheets31aand31bare substantially constant unless the kind, the size and so forth of the paper sheet are changed. Thus, when the image-exposure positions EA1and EB1are staggered and the image-exposure positions EA2and EB2are staggered, it is possible to judge the image-exposure position overlapping with an occurrence position of scanning unevenness in case of occurrence thereof. Consequently, it is possible to specify the roller having a cause of the scanning unevenness.

In the meantime, when the anterior ends of the paper sheets31aand31bhaving different sizes are staggered by Δd (the paper sheet31ahas a shorter size and the paper sheet31bis ahead) such as shown inFIG. 15, the press-starting position A1of the second press roller74and the nip-starting position B1of the second nip roller50are determined on the basis of the position of the anterior end of the paper sheet31abeing behind. In addition, the nip-terminating position B2of the first nip roller46and the press-terminating position of the first press roller73are determined on the basis of the posterior end of the paper sheet31ahaving the shorter size. Also in this case, the image-exposure positions EA1and EB1are staggered, and the image-exposure positions EA2and EB2are staggered.

Incidentally, when the exposure is performed for the paper sheets31aand31bstaggered such as shown inFIGS. 14 and 15, and when the shift amount Δd of the anterior ends is known, the image data to be recorded on the paper sheets31aand31bis stored in the image memory (not shown) of the exposing unit38in a state that the anterior ends are shifted by the shift amount Δd. By doing so, it is possible to record the images on the paper sheets31aand31bwith great accuracy. When the shift amount Δd of the anterior ends falls in a predetermined range, exposing both the paper sheets31aand31bmay be simultaneously commenced without shifting the image data to be recorded on the paper sheets31aand31b.

Such as described above, in the feeder39of this embodiment, it is unnecessary to dispose the first and second feed-roller pairs43and44in parallel such as described in the forgoing Publication No. 2003-241321 so that the mechanism there of maybe simplified. Further, it is possible to prevent the scanning unevenness from occurring due to slight vibration, which is caused relative to the adjacent rows at the time of nipping and at the time of releasing the nip. Thus, control may be easily performed. Such as shown inFIGS. 14 and 15, the image-exposure positions EA1and EB1are staggered, and the image-exposure positions EA2and EB2are staggered. In virtue of this, even if the scanning unevenness occurs, it is easily identified, by confirming the occurrence position of the scanning unevenness of the paper sheets31aand31b, that which of the nip rollers and the press rollers causes the scanning unevenness.

The exposed paper sheets31aand31bare carried from the exposure section20to the processing unit22wherein various processes of coloring/developing, fixing, washing and drying are executed. After that, the paper sheet is discharged to the outside of the photo printer10as the photo print.

In the photo printer10of the above embodiment, the paper sheets31aand31bare fed in two rows. However, the number of the paper-sheet rows is not limited to two, but may be three or more. In this case, the first and second feed-roller pairs43and44are exchanged so as to correspond to the row number of the paper sheets31. In addition, the photo sensors are disposed in parallel so as to correspond to the increased number. Meanwhile, in the forgoing embodiment, the cam unit52is used to move the first and second nip rollers46,50and the first and second press rollers73,74. The present invention, however, is not limited to this. The respective rollers46,50,73and74may be independently moved by shifting mechanisms provided for the respective rollers.

In the forgoing embodiment, the magazines12and13are vertically arranged in parallel. Instead of this arrangement, the paper sheets31aand31bmay be arranged in parallel in the width direction thereof. Further, instead of disposing the plural magazines, a plurality of the recording-paper rolls29may be set in the sole magazine. Furthermore, a sorter (not shown) for moving the paper sheets31aand31bin the width direction thereof may be used to arrange the paper sheets31aand31bin parallel. When the sorter is employed, the positions of the paper sheets31aand31bin the scanning direction may be adjusted by using this sorter.

In the meantime, an application example of the feeder39is described below. When an image is recorded on a paper sheet87fed in a single row and in an inclined state such as shown inFIG. 16, a direction of the inclined paper sheet87is detected on the basis of time-difference information, which is obtained when the anterior end and the posterior end of the paper sheet87pass the photo sensors82aand82b. For example, in case the paper sheet87inclines in a counterclockwise direction, the press-starting position A1of the second press roller74and the nip-starting position B1of the second nip roller50may be determined on the basis of a delay side (shown by an indicia ◯ in the drawing) of the anterior end of the paper sheet87detected by the photo sensor82a. In addition, the nip-terminating position B2of the first nip roller46and the press-terminating position A2may be determined on the basis of an early side (shown by an indicia ● in the drawing) of the posterior end of the paper sheet87detected by the photo sensor82b. Also in this case, in order to specify the roller having a cause of the scanning unevenness, it is preferable that the image-exposure positions EA1and EB2are staggered, and the image-exposure positions EA2and EB2are staggered.

In the forgoing embodiment, the second feed-roller pair44is switched to the nip position after the lastly detected anterior end of the paper sheets31aand31bhas passed through the second feed-roller pair44kept in the nip-releasing state. Moreover, the first feed-roller pair43is switched to the nip-releasing state before the firstly detected posterior end leaves the first feed-roller pair43kept in the nip state. The present invention, however, is not exclusive to this. For example, when a degree of occurrence of the scanning unevenness is small, the first and second feed-roller pairs43and44kept in the nip state may be switched to a weak nip state, in which force for nipping the paper sheets31aand31bare weakened in comparison with the nip state, instead of being switched to the nip-releasing state.

In this case, it is unnecessary to move the first and second nip rollers46and50respectively from the nip position to the release position. Such as shown inFIG. 17A, for instance, it is sufficient to move the second nip roller50to the weak nip position separated by a distance t2, which is equal to a thickness t1of the paper sheets31aand31b, when the anterior ends of the paper sheets31aand31bpass through the second feed-roller pair44. Further, when the posterior ends of the paper sheets31aand31bpass through the first feed-roller pair43, it is similarly sufficient to move the first nip roller46to the weak nip position separated by the distance t2, such as shown inFIG. 17B.

Instead of moving the first and second nip rollers46and50to the weak nip position, pressure force for pressing the first and second nip rollers46and50against the first and second capstan rollers45and49may be weakened in comparison with the nip state, such as shown inFIGS. 18A and 18b. In this case, it is sufficient to move the first and second nip rollers46and50from the nip position so as not to release the nip of the paper sheets31aand31b.