Title:
Feeding apparatus for sheet-shaped recording material and image recording apparatus
Kind Code:
A1


Abstract:
Feeding roller pairs are respectively constituted of a capstan roller and a nip roller. The nip roller is movable between a nip position and a release position. A couple of position sensors are disposed along a passage of a recording-paper sheet. The downstream nip roller is moved to the nip position when a time T2 has passed after detecting an anterior end of the sheet with the downstream position sensor. The upstream nip roller is moved to the release position when a time T3 has passed after detecting a posterior end of the sheet with the upstream position sensor. Test prints are prepared as the times T2 and T3 are changed. Patterns of the test prints are observed, and the times T2 and T3 are altered by selecting a number of the optimum test print.



Inventors:
Ono, Takehisa (Kanagawa, JP)
Application Number:
10/939384
Publication Date:
03/17/2005
Filing Date:
09/14/2004
Assignee:
ONO TAKEHISA
Primary Class:
International Classes:
G03B27/46; B65H5/06; G03B27/58; H04N1/00; (IPC1-7): B65H5/02
View Patent Images:



Primary Examiner:
JOERGER, KAITLIN S
Attorney, Agent or Firm:
BIRCH, STEWART, KOLASCH & BIRCH, LLP (FALLS CHURCH, VA, US)
Claims:
1. A feeding apparatus for a sheet-shaped recording material, in which an upstream roller pair and a downstream roller pair are respectively disposed at an upstream side and a downstream side of a record position in a feeding direction of said recording material, and an upstream movable roller constituting said upstream roller pair and a downstream movable roller constituting said downstream roller pair are respectively movable between a nip position for nipping and feeding said recording material, and a release position for releasing the nip of said recording material, said feeding apparatus comprising: a first moving mechanism for moving said upstream movable roller to said release position before a posterior end of said recording material passes through said upstream roller pair; a second moving mechanism for moving said downstream movable roller to said nip position after an anterior end of said recording material has passed through said downstream roller pair; and a controller for enabling drive start timing of at least one of said first moving mechanism and said second moving mechanism to be changed.

2. A feeding apparatus for a sheet-shaped recording material according to claim 1, further comprising: a first position sensor disposed at an upstream side of said upstream roller pair in the feeding direction of said recording material; and a second position sensor disposed at an upstream side of said downstream roller pair in the feeding direction of said recording material, wherein said controller enables each of a first waiting time and a second waiting time to be changed, said first waiting time being taken for starting a drive of said first moving mechanism after detecting the posterior end of said recording material with said first position sensor, and said second waiting time being taken for starting a drive of said second moving mechanism after detecting the anterior end of said recording material with said second position sensor.

3. A feeding apparatus for a sheet-shaped recording material according to claim 2, wherein said first waiting time and said second waiting time are settable in accordance with a width and a kind of said recording material.

4. A feeding apparatus for a sheet-shaped recording material according to claim 1, further comprising: a single pulse motor for driving said first moving mechanism and said second moving mechanism.

5. A feeding apparatus for a sheet-shaped recording material according to claim 4, wherein said first moving mechanism includes: an eccentric cam rotated by said pulse motor; and a first drive lever, one end of which abuts on said eccentric cam and the other end of which is connected to said upstream movable roller, said first drive lever rotating in association with a rotation of said eccentric cam to move said upstream movable roller between said nip position and said release position.

6. A feeding apparatus for a sheet-shaped recording material according to claim 5, wherein said second moving mechanism includes: a second drive lever, one end of which abuts on said eccentric cam and the other end of which is connected to said downstream movable roller, said second drive lever rotating in association with the rotation of said eccentric cam to move said downstream movable roller between said nip position and said release position.

7. A feeding apparatus for a sheet-shaped recording material according to claim 4, wherein said first moving mechanism includes: a drive cam rotated by said pulse motor; a first eccentric cam fixed to said drive cam and integrally rotating therewith; a first cam follower abutting on said first eccentric cam, said first cam follower moving in association with a rotation of said first eccentric cam in a radius direction of said drive cam; and a first base member for supporting said first cam follower and said upstream movable roller, said first base member rotating in association with a movement of said first cam follower to move said upstream movable roller between said nip position and said release position.

8. A feeding apparatus for a sheet-shaped recording material according to claim 7, wherein said second moving mechanism includes: a second eccentric cam fixed to said drive cam and integrally rotating therewith; a second cam follower abutting on said second eccentric cam, said second cam follower moving in association with a rotation of said second eccentric cam in the radius direction of said drive cam; and a second base member for supporting said second cam follower and said downstream movable roller, said second base member rotating in association with a movement of said second cam follower to move said downstream movable roller between said nip position and said release position.

9. An image recording apparatus for recording an image on a sheet-shaped recording material, in which an upstream roller pair and a downstream roller pair are respectively disposed at an upstream side and a downstream side of a record position, where image recording is performed, in a feeding direction of said recording material, and an upstream movable roller constituting said upstream roller pair and a downstream movable roller constituting said downstream roller pair are respectively movable between a nip position for nipping and feeding said recording material, and a release position for releasing the nip of said recording material, said image recording apparatus comprising: a first moving mechanism for moving said upstream movable roller to said release position before a posterior end of said recording material passes through said upstream roller pair; a second moving mechanism for moving said downstream movable roller to said nip position after an anterior end of said recording material has passed through said downstream roller pair; and a controller for enabling drive start timing of at least one of said first moving mechanism and said second moving mechanism to be changed.

10. An image recording apparatus according to claim 9, further comprising: a first position sensor disposed at an upstream side of said upstream roller pair in the feeding direction of said recording material; and a second position sensor disposed at an upstream side of said downstream roller pair in the feeding direction of said recording material, wherein said controller enables each of a first waiting time and a second waiting time to be changed, said first waiting time being taken for starting a drive of said first moving mechanism after detecting the posterior end of said recording material with said first position sensor, and said second waiting time being taken for starting a drive of said second moving mechanism after detecting the anterior end of said recording material with said second position sensor.

11. An image recording apparatus according to claim 10, wherein said image recording apparatus produces a plurality of test prints on which solid patterns are recorded at a leading side and a trailing side of said recording material in the feeding direction, and said controller changes at least one of the first waiting time and the second waiting time whenever said test print is produced.

12. An image recording apparatus according to claim 11, wherein a print number is recorded on said test print, and said controller sets the first waiting time and the second waiting time so as to correspond to the selected print number.

13. An image recording apparatus according to claim 11, wherein at least one of indications representing the leading side and the trailing side is recorded on said test print.

14. An image recording apparatus according to claim 11, wherein information concerning the first waiting time and the second waiting time is recorded on said test print.

15. An image recording apparatus according to claim 10, further comprising: a removable magazine loaded with said recording material and having a different ID number in accordance with a width and a kind of said recording material, said controller enabling the first waiting time and the second waiting time to be set for the respective ID numbers.

16. An image recording apparatus according to claim 10, further comprising: a single pulse motor for driving said first moving mechanism and said second moving mechanism.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a feeding apparatus for a sheet-shaped recording material, and further relates to an image recording apparatus for recording an image by using this feeding apparatus.

2. Description of the Related Art

A photo printer for recording an image on a sheet-shaped photosensitive material is widely known. In this kind of the photo printer, recording light is applied in a scanning direction while the photosensitive material is fed in a sub-scanning direction perpendicular to the scanning direction. The photo printer includes a plurality of feeding roller pairs comprising a capstan roller and a nip roller. The recording material is nipped and fed by the feeding roller pair.

In order to prevent density unevenness of a recording image to be caused by fluctuation of a feeding speed, it is necessary to accurately feed the photosensitive material at the time of image recording. In view of this, Japanese Patent Laid-Open Publication No. 2001-33883 teaches nip rollers respectively disposed at an upstream side and a downstream side of a record head for irradiating the recording light. The nip roller is movable between a nip position where the photosensitive material is nipped, and a release position where the nip is released. The respective nip rollers start to move when an anterior end or a posterior end of the photosensitive material has reached a predetermined position. In virtue of this, nipping and releasing the photosensitive material are performed at prescribed timing in accordance with a length and a feeding speed of the photosensitive material. Thus, quality of the recording image may be kept in a good condition.

Meanwhile, Japanese Patent Laid-Open Publication No. 2002-3002 teaches nip rollers of an upstream side and a down stream side, which are moved by a single pulse motor. A movement speed of the nip roller is changed in accordance with a length of the photosensitive material. By doing so, shock to be caused to the photosensitive material is reduced when a feeding roller pair performs nipping and releasing.

A feeding mechanism for the photosensitive material and a moving mechanism for the nip roller employ some parts. Sizes of the respective parts are not perfectly same relative to all of the mechanisms. Machining errors are caused in each mechanism by a little. When timing for nipping the photosensitive material with the nip roller strays from a design value and when timing for releasing the nip strays from a design value, the feeding speed of the photosensitive material fluctuates during recording. At this time, density unevenness is likely to occur in the image recorded on the photosensitive material.

Thicknesses and curling characteristics of the photosensitive materials are different in accordance with sorts thereof. Even if the curling characteristics are identical, a curl amount of the photosensitive material in a scanning direction is larger as the photosensitive material has a longer width. Due to this, the timing for nipping the photosensitive material with the nip roller is shifted from the design value. Also in this case, the density 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 a feeding apparatus in which nipping a recording material and releasing the nip are performed at optimum timing in accordance with characteristics of the recording material and accuracy scatter of parts constituting the apparatus.

It is a second object of the present invention to provide an image recording apparatus including the above-mentioned feeding apparatus.

In order to achieve the above and other objects, the feeding apparatus according to the present invention comprises an upstream roller pair and a downstream roller pair disposed at an upstream side and a downstream side of a record position in a feeding direction of a sheet-shaped recording material. An upstream movable roller and a downstream movable roller constituting the upstream and downstream roller pairs are respectively movable between a nip position for nipping and feeding the recording material, and a release position for releasing the nip. The feeding apparatus further comprises a first moving mechanism and a second moving mechanism. The first moving mechanism moves the upstream movable roller to the release position before a posterior end of the recording material passes the upstream roller pair. The second moving mechanism moves the downstream movable roller to the nip position after an anterior end of the recording material has passed the downstream roller pair. The feeding apparatus further comprises a controller for enabling drive start timing of at least one of the first and second moving mechanisms to be changed.

In a preferred embodiment, a first position sensor and a second position sensor are respectively disposed at upstream sides of the upstream and downstream roller pairs in the feeding direction of the recording material. After the first position sensor has detected the posterior end of the recording material, a waiting time (first waiting time) is taken until the first moving mechanism is driven. After the second position sensor has detected the anterior end of the recording material, a waiting time (second waiting time) is taken until the second moving mechanism is driven. By changing the first and second waiting times, the drive start timing of the first and second moving mechanisms can be changed.

A plurality of test prints may be prepared as the first waiting time and the second waiting time are changed. On the test print, solid patterns are recorded at leading and trailing sides thereof in the feeding direction of the recording material. It is preferable that a print number is recorded on the test print. Further, it is preferable that the first waiting time and the second waiting time are set so as to correspond to the selected print number.

It is preferable that at least one of indications for representing the leading and trailing sides is recorded on the test print. Moreover, it is preferable that information concerning the first waiting time and the second waiting time is recorded on the respective test prints.

A magazine, which has a different ID number in accordance with a width and a type of the recording material to be contained, may be removably attached. The first waiting time and the second waiting time may be set for each ID number. Meanwhile, it is preferable that the first moving mechanism and the second moving mechanism are driven by a single pulse motor.

According to the present invention, it is possible to nip the recording material and to release the nip at optimum timing in accordance with the characteristics of the recording material and the accuracy scatter of parts constituting the apparatus. Moreover, changing the drive start timing may be easily performed. Further, it is possible to determine the optimum drive start timing by observing the solid pattern recorded on the test print. Furthermore, the drive start timing may be easily set in accordance with the width and the type of the recording material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the invention when read in conjunction with the accompanying drawings, in which:

FIG. 1 is an explanatory illustration schematically showing a structure of a printer;

FIG. 2 is a plan view schematically showing a structure of a feeding mechanism, wherein nip rollers of an upstream side and a downstream side are kept in a release position;

FIG. 3 is a plan view schematically showing the structure of the feeding mechanism, wherein the upstream nip roller is kept in a nip position and the downstream nip roller is kept in the release position;

FIG. 4 is a plan view schematically showing the structure of the feeding mechanism, wherein both of the nip rollers are kept in the nip position;

FIG. 5 is a plan view schematically showing the structure of the feeding mechanism, wherein the upstream nip roller is kept in the release position and the downstream nip roller is kept in the nip position;

FIG. 6 is a timing diagram showing speed variation of drive pulses to be supplied to a pulse motor;

FIG. 7 is an explanatory illustration showing a picture displayed when movement timing of the nip roller is adjusted;

FIG. 8 is a perspective view showing a test print;

FIG. 9 is a flowchart explaining a sequence for preparing the test print;

FIG. 10 a perspective view schematically showing another embodiment of the feeding mechanism; and

FIG. 11 is a plan view schematically showing a structure of the feeding mechanism shown in FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

An embodiment of the present invention is described below, referring to the drawings. As shown in FIG. 1, a printer 10 constituting a photo printer includes an upper magazine 11, a lower magazine 12, cutters 13 and 14, a back-printing unit 15, an image recorder 16 and a sorter 17.

The upper magazine 11 and the lower magazine 12 are vertically set in a recording-paper chamber provided inside the printer 10. Each of the magazines 11 and 12 contains a recording-paper roll 22 in which a sheet-shaped photosensitive recording paper 21 to be used as a recording material is wound in a roll form. The recording paper 21 is formed such that a surface of at least an emulsion coating side (image recording side) of a substrate is covered with a composition, in which white pigment is mixed and dispersed in a resin including polyester or the like. The substrate is made of a base paper and so forth. Meanwhile, paper-feed roller pairs 23 are disposed near paper mouths of the magazines 11 and 12. When the paper-feed roller pair 23 is rotated by a drive motor, which is not shown, the recording paper 21 is drawn out of the recording-paper roll 22 and is advanced toward the respective cutters 13 and 14.

The magazines 11 and 12 have unique ID numbers (magazine ID) in accordance with a width and a type of the photosensitive recording paper 21. As to the magazine ID, there are sixty-four kinds, for example. When the magazines 11 and 12 are set, the magazine ID is optically or magnetically read by a reader, which is not shown. By adjusting a setting value, which is described later, relative to each magazine ID, it is possible to deal with a gap of feed timing to be caused due to differences of the paper width and the type.

The cutters 13 and 14 are respectively constituted of fixed blades 13a and 14a and movable blades 13b and 14b, which are disposed across a passage of the recording paper 21. When an anterior end of the recording paper 21 is advanced from the respective cutters 13 and 14 by a predetermined length, a cutter driving mechanism not shown is actuated to move the movable blades 13a and 14b toward the fixed blades 13a and 14a. Thereupon, the recording paper 21 is cut to produce a recording-paper sheet 24 having the predetermined length. Incidentally, instead of the double cutters, a single cutter may be disposed near the back-printing unit 15.

The recording-paper sheet 24 is transported toward the back-printing unit 15 by advancing roller pairs 25 and along a guide rail, which is not shown. In the back-printing unit 15, necessary information including film ID, a frame number and so forth is printed on a rear surface (opposite surface to an emulsion layer) of the recording-paper sheet 24.

The recording-paper sheet 24 for which back printing has been performed is transported to the image recorder 16 by advancing roller pairs 26 and 27. The image recorder 16 is constituted of an exposure device 28 for radiating recording light toward the recording-paper sheet 24, and a feeding mechanism for moving the recording-paper sheet 24 in the image recorder 16. The feeding mechanism comprises a first feeding roller pair 30 for feeding the recording-paper sheet 24 to an exposure position, and a second feeding roller pair 31 for feeding the exposed sheet 24 to a belt conveyor 32.

The exposure device 28 comprises a well-known laser printer and an image memory for storing image data read by a film scanner, which is not shown. Alternatively, the image memory stores image data outputted from a recording medium of a memory card or the like, which is not shown. The laser printer irradiates the recording-paper sheet 24 with a laser, whose intensity is modulated on the basis of the image data stored in the image memory, to perform exposure recording of an image. The exposed sheet 24 is advanced to the belt conveyor 32. The recording-paper sheets 24 are sorted into plural rows by the sorter 17 while transported by the belt conveyor 32. And then, the recording-paper sheet 24 is advanced to a processing unit (not shown) wherein various processes of coloring, fixing and washing are performed. After these processes, a drying process is performed in the processing unit. Ultimately, the recording-paper sheet is discharged to the outside of the printer as a photo print.

FIG. 2 schematically shows the feeding mechanism of the image recorder 16. The first feeding roller pair 30 is constituted of a capstan roller 33 and a nip roller 34 being as a driven roller, which are disposed so as to nip an upper side of a guide member 49. Similarly, the second feeding roller pair 31 is constituted of a capstan roller 35 and a nip roller 36 being as a driven roller, which are disposed so as to nip the upper side of the guide member 49. The capstan roller 33 of the first feeding roller pair 30 is connected to a motor 37 via a gear train, which is not shown. As to the motor 37, is used a pulse motor having one hundred rotor teeth and five phases, for example. Drive pulses are supplied to the motor 37 so as to always rotate it at uniform velocity. Incidentally, an inelastic steal belt 38 is laid between the capstan rollers 33 and 35, which are rotated at the uniform velocity by the sole motor 37.

Upon activating the motor 37 to rotate the capstan rollers 33 and 35, the recording-paper sheet 24 nipped by the nip rollers 34 and 36 is transported at a constant speed in a direction shown by an arrow (in a sub-scanning direction). When the recording-paper sheet 24 passes the exposure position 39, the exposure device 28 applies the laser beam in a scanning direction (in a perpendicular direction relative to the drawing), which intersects with the sub-scanning direction at right angles, to perform the exposure one line by one line. Incidentally, the advancing roller pair 27 (see FIG. 1) comprises a one-way clutch. A conveyance speed of the sheet 24 conveyed by the roller pair 27 is determined so as to be smaller than a feed speed of the sheet 24 fed by the first feeding roller pair 30. Consequently, the advancing roller pair 27 becomes free at the moment that the recording-paper sheet is nipped and fed by the first feeding roller pair 30. Thus, it is possible to hold down speed fluctuation to be caused by movement transition of the recording-paper sheet 24.

The nip rollers 34 and 36 are rotatably supported by brackets 40 and 41 respectively disposed at both sides thereof in the scanning direction. The brackets 40 and 41 are guided by guide plates, which are not shown, so as to be vertically movable. The brackets 40 and 41 are urged toward the capstan rollers 33 and 35 with compression springs 42 and 43 by which the nip rollers 34 and 36 are pressed against the capstan rollers 33 and 35 to nip the recording-paper sheet 24.

Elongate holes 40a and 41a formed in the brackets 40 and 41 respectively engage with guide pins 45a and 46a formed at ends of drive levers 45 and 46. The drive levers 45 and 46 are rotatably attached to each other by an attachment shaft 48 so as to intersect. Cam followers 50 and 51 attached to the other ends of the drive levers 45 and 46 abut on a peripheral surface of an eccentric cam 52. Upon rotating the eccentric cam 52, the other ends of the drive levers 45 and 46 are pushed so that the drive levers 45 and 46 are rotated around the attachment shaft 48. Owing to this, the nip rollers 34 and 36 are vertically moved between the nip position for nipping the recording-paper sheet 24, and the release position for releasing the nip of the recording-paper sheet 24.

A rotary shaft 53 of the eccentric cam 52 is connected to a pulse motor 55 via a gear train, which is not shown. The pulse motor 55 is activated by receiving drive pulses from the controller 56 controlling the operation of the printer 10. When the pulse motor 55 is driven to rotate an output shaft thereof, the eccentric cam 52 is rotated around the rotary shaft 53 in a clockwise direction. The output shaft of the pulse motor 55 is rotated by a predetermined angle per one drive pulse. Thus, by counting a number of the drive pulses with a counter 57, it is possible to detect a rotational position of the eccentric cam 52, namely movement positions of the nip rollers 34 and 36. Meanwhile, a reference-position sensor 60 is disposed near the pulse motor 55. The reference-position sensor 60 comprises a light emitting portion and a light receiving portion to detect a passage of a projection 55a formed on the output shaft of the pulse motor 55.

First and second position sensors 63 and 64 for detecting the passage of the recording-paper sheet 24 are respectively disposed at the upstream sides of the nip rollers 34 and 36. Each of the first and second position sensors 63 and 64 is constituted of a light emitting portion and a light receiving portion. The light emitting portion radiates the light downward in the drawing, and the light receiving portion detects the reflected light. When intensity of the reflected light has changed, it is detected that the anterior end or the posterior end of the recording-paper sheet 24 has passed.

When the recording-paper sheet 24 is not fed, the eccentric cam 52 is stopped at a position where the reference-position sensor 60 detects the projection 55a. At this time, the eccentric cam 52 depresses the other ends of the drive levers 45 and 46 so as to keep each of the nip rollers 34 and 36 in the releasing position. Thus, the nip rollers 34 and 36 are prevented, at the time of nonuse, from being pressed against the capstan rollers 33, 35 and from being deformed.

When the recording-paper sheet 24 is transported and the anterior end thereof is detected by the first position sensor 63, the controller 56 supplies the drive pulse to the pulse motor 55 to rotate the eccentric cam 52 from the position shown in FIG. 2 to the position shown in FIG. 3. By rotating the eccentric cam 52, the drive lever 45 is rotated in a counterclockwise direction. The nip roller 34 of the upstream side is gradually moved downward and is stopped at the nip position shown in FIG. 3.

The recording-paper sheet 24 is nipped and fed by the first feeding roller pair 30 and the anterior end thereof passes the second position sensor 64. Then, the eccentric cam 52 is rotated in the clockwise direction from the position shown in FIG. 3 to the position shown in FIG. 4 to merely rotate the drive lever 46. Only the nip roller 36 of the downstream side is gradually moved toward the nip position in the state that the nip roller 34 of the upstream side is kept in the nip position. After the anterior end of the recording-paper sheet 24 has passed the second feeding roller pair 31, the nip roller 36 reaches the nip position shown in FIG. 4. Thus, it is possible to eliminate a shock when the recording-paper sheet 24 enters the second feeding roller pair 31.

The recording-paper sheet 24 is nipped by the first and second roller pairs 30 and 31. In this state, the recording-paper sheet 24 is fed at a constant speed in the sub-scanning direction shown by an arrow in the drawing. And then, the posterior end of the recording-paper sheet 24 passes the first position sensor 63. Thereupon, the pulse motor 55 is driven and the eccentric cam 52 is rotated from the position shown in FIG. 4 to the position shown in FIG. 5 to merely rotate the drive lever 45. Owing to this, the nip roller 34 of the upstream side commences to move to the releasing position shown in FIG. 5 in the state that the nip roller 36 of the downstream side is kept in the nip position. Before the posterior end of the recording-paper sheet 24 passes the first feeding roller pair 30, the upstream nip roller 34 is separated from the recoding-paper sheet 24. Thus, it is possible to eliminate a shock when the recording-paper sheet 24 passes through the first feeding roller pair 30.

After that, the recording-paper sheet 24 is advanced only by the second feeding roller pair 31 of the downstream side. When it is detected that the posterior end of the recording-paper sheet 24 has passed the second position sensor 64, the controller 56 supplies the drive pulse to the pulse motor 55 to rotate the eccentric cam 52 from the position shown in FIG. 5 to the position shown in FIG. 2. The nip roller 36 of the downstream side commences to move to the release position in the state that the nip roller 34 of the upstream side is kept in the release position. Consequently, the nip of the second feeding roller pair 31 is released.

As shown in FIG. 2, the printer 10 is provided with a ROM 70, a RAM 71, a display 72 and an operation inputting portion 73, which are connected to the controller 56 via a data bus 74. The ROM 70 stores a control program for driving the nip rollers 34 and 36. The control program is read by the controller 56 at the time of recording an image. Further, the ROM 70 stores initial value data of various setting values including speeds (S1 and S2 described later) of the drive pulses to be supplied to the pulse motor 55 for moving the nip rollers 34 and 36, numbers (P1 through P4 described later) of the drive pulses to be supplied to the pulse motor 55 in the respective movement stages of the nip rollers 34 and 36, time lags (T1 through T5 described later) to be taken for driving/stopping the pulse motor 55 after the position sensors 63 and 64 have detected the recording-paper sheet 24.

When the setting values have been changed, the changed values are stored in the RAM 71. The display 72 shows various pictures regarding the change of the setting values, print selection and so forth. A user can change the setting value and can select the image to be printed by handling the operation inputting portion 73 comprising a mouse and a keyboard.

An operation of the feeding mechanism having the above structure is described below, referring to a timing diagram shown in FIG. 6. When the recording-paper sheet 24 is not fed or when the first position sensor 63 does not detect the anterior end of the sheet 24 notwithstanding the transport thereof, the reference-position sensor 60 makes the pulse motor 55 stop in a state that the output shaft thereof is set to an origin position. At this time, both the nip rollers 34 and 36 are kept in the release position to prevent the peripheral surface of the rollers from being deformed.

When the recording-paper sheet 24 is fed and the anterior end thereof is detected by the first position sensor 63, driving the pulse motor 55 is commenced after a time T1 to move the upstream nip roller 34 toward the nip position. The speed of the drive pulse to be supplied to the pulse motor 55 increases at a fixed rate and becomes a constant value S1. Incidentally, this drive-pulse speed corresponds to a movement speed of the nip roller 34. After that, the speed of the drive pulse decreases at a fixed rate and becomes zero when the nip roller 34 reaches the nip position. The drive pulses of a predetermined number P1 are supplied to the pulse motor 55 until the nip roller 34 reaches the nip position. It is possible to surely stop the nip roller 34 at the nip position by counting the number of the drive pulses, which are supplied to the pulse motor 55, with the counter 57.

The first feeding roller pair 30 of the nipping state feeds the recording-paper sheet 24 in the sub-scanning direction. When a leading edge of a recording area of the recording-paper sheet 24 has reached the exposure position 39, the exposure device 28 is driven to record an image on the sheet 24 one line by one line. When the second position sensor 64 detects the anterior end of the recording-paper sheet 24, the pulse motor 55 commences to rotate after a time T2 so that the downstream nip roller 36 is moved toward the nip position. The speed of the drive pulse to be supplied to the pulse motor 55 increases at a fixed rate and becomes a constant value S2. Incidentally, this drive-pulse speed corresponds to a movement speed of the nip roller 36. After that, the speed of the drive pulse decreases at a fixed rate and becomes zero when the nip roller 36 has reached the nip position (when the pulses of a number P2 have been supplied).

As will be apparent from FIG. 6, in the drive sequence for moving the downstream nip roller 36 to the nip position, the drive-pulse speed S2 is smaller than the drive-pulse speed S1 for moving the upstream nip roller 34 to the nip position. Thus, it is possible to hold down a shock to be caused when the downstream nip roller 36 abuts on the recording-paper sheet 24 during the image recording. Consequently, exposure unevenness may be reduced.

The image recording is performed in the state that the recoding-paper sheet 24 is nipped and fed by the first and second roller pairs 30 and 31. When the first position sensor 63 detects the posterior end of the recording-paper sheet 24, the pulse motor 55 commences to rotate after a time T3 to move the upstream nip roller 34 to the release position. The speed of the drive pulse to be supplied to the pulse motor 55 increases at a fixed rate and becomes the constant value S2. Incidentally, this drive-pulse speed corresponds to the movement speed of the nip roller 34. After that, the speed of the drive pulse decreases at a fixed rate and becomes zero when the nip roller 34 has reached the release position (namely, when the pulses of a number P3 have been supplied). Consequently, the nip roller 34 is stopped. The drive-pulse speed of this movement stage is also determined so as to be smaller, similarly to the stage for moving the downstream nip roller 36 to the nip position. Owing to this, it is possible to reduce a shock to be caused at the moment that the nip roller 34 is separated from the recording-paper sheet 24. Thus, the exposure unevenness to be caused in association with the fluctuation of the feeding speed may be effectively held down.

After that, the recording-paper sheet 24 is transported in the sub-scanning direction by the second feeding roller pair 31 kept in the nip state. When the second position sensor 64 detects the posterior end of the recording-paper sheet 24, the pulse motor 55 commences to rotate after a time T4 to move the downstream nip roller 36 to the release position. The speed of the drive pulse to be supplied to the pulse motor 55 increases at a fixed rate and becomes the constant value S1. Incidentally, this drive-pulse speed corresponds to the movement speed of the nip roller 36. And then, the speed of the drive pulse decreases at a fixed rate and becomes zero when the nip roller 36 has reached the release position (namely, when the pulses of a number P4 have been supplied). Consequently, the nip roller 36 is stopped. In the stage for moving the downstream nip roller 36 to the release position, the pulse motor 55 is controlled so as to be stopped when the drive pulses of a number P5 has been counted after detecting the projection 55a with the reference-position sensor 60.

By the above-described operation, one sheet 24 passes the exposure device 28. Successively, the similar operation is performed when the next sheet 24 reaches the exposure device 28. In doing so, the recording-paper sheets 24 are fed in the condition that the shock to be caused by the nipping/releasing operation of the nip rollers 34 and 36 is held down.

A driving mechanism of the capstan rollers 33 and 35 for feeding the recording-paper sheet 24 is constituted of some parts. A moving mechanism of the nip rollers 34 and 36 is also constituted of some parts. Due to machining errors of the respective parts and due to differences concerning thicknesses and curling characteristics of the recording-paper sheet 24, timing for nipping the recording-paper sheet 24 with the nip rollers and timing for releasing the nip sometimes stray from design values. At this time, density unevenness is likely to occur in an image to be recorded on the recording-paper sheet 24.

In view of this, the timing for nipping/releasing the recording-paper sheet 24 is adapted to be regulated by changing the setting values T2 and T3. Such as shown in FIG. 7, the display 72 shows a picture for changing the setting values. An operator can change the setting value by handling the operation inputting portion 73.

First of all, the operator selects the magazine ID of which the setting value is desired to be changed. The magazine ID is selected by clicking either of items 80 and 81. The item 80 represents the entire magazine IDs, and the item 81 represents the used magazine ID. When the item 80 is selected, the setting value is changed relative to the entire magazine IDs used in the printer 10. Meanwhile, when the item 81 is selected, the setting value is changed relative to only the magazine currently used.

Successively, the magazine to be used for a test print is designated. In addition, a length of the test print is also designated by clicking a print-length designation box 82 and by selecting a desired print length. In a magazine selection area 83, are indicated items for selecting either of the upper magazine 11 and the lower magazine 12. Moreover, information concerning the paper width and the paper type, which are read from the ROM 70 so as to correspond to the selected magazine ID, are also indicated in the magazine selection area 83. A side of the magazine selection area 83 is provided with a print button 84. By clicking this print button 84, the test print is prepared.

Such as shown in FIG. 8, an anterior solid pattern 101 and a posterior solid pattern 102 are recorded at both ends of the test print in the sub-scanning direction. Moreover, indications 103 and 104 representing “anterior end” and “posterior end” are recorded near the respective solid patterns 101 and 102 to easily distinguish the anterior solid pattern 101. Further, print information 105 are recorded in an unrecorded region of the test print 100 (between the solid patterns 101 and 102). The print information 105 represents a test print number and values of T2 and T3, which are determined so as to correspond to the respective number. The print information 105 may be recorded by using the back-printing unit 15.

Upon clicking the print button 84, nine test prints 100 are prepared as the values of T2 and T3 are changed. Given that the values of T2 and T3 are represented as T2(N) and T3(N) when the Nth (N=1 to 9) test print is produced, the initial values stored in the ROM 70 are defined as T2(5) and T3(5), and the values of T2 and T3 are increased and decreased by 1 msec. in association with the change of N. In other words, T2(N) and T3(N) are expressed by the following equations.
T2(N)=T2(5)+(N−5)
T3(N)=T3(5)+(N−5)
The data representing the values of T2(N) and T3(N) is recorded in the ROM 70. As a matter of course, it is not exclusive to increase and decrease the T2 and T3 by 1 msec., and optional values may be determined. By the way, unit of the value is msec. in the above equations.

As shown in a flowchart of FIG. 9, the variable N is initialized to one when the print button 84 is clicked (step S10). Successively, the values of T2(1) and T3(1) are read from the ROM 70 (step S12), and feeding the recording-paper sheet 24 is commenced (step S14). While the recording-paper sheet 24 is fed, the anterior solid pattern 101, the print information 105 and the posterior solid pattern 102 are recorded in this order (steps S16, S18 and S20). And then, the first test print 100 is discharged (step S22). After that, it is judged whether the variable N is nine or not, namely whether or not all of the test prints 100 are prepared (step S24). When the variable N is not nine, one is added to the variable N (step S26) and the operations of the steps S12 to S24 are repeated. Producing the test prints is over when all of the test prints 100 have been prepared.

By changing the value of T2, the nip timing of the nip roller 36 of the second feeding roller pair 31 is changed. Thus, density-unevenness properties of the anterior solid pattern 101 are changed every print number. Similarly, by changing the value of T3, the release timing of the nip roller 34 of the first feeding roller pair 31 is changed. Thus, density-unevenness properties of the posterior solid pattern 102 are changed. The operator observes the solid patterns 101 and 102 to extract the number of the test print in which the solid pattern having the minimum density unevenness is recorded. Extracting the number is performed relative to each of the anterior side and the posterior side. And then, an anterior-number selection box 85 and a posterior-number selection box 86 are respectively clicked to select the optimum numbers. The changed setting value is recorded in the RAM 71 by clicking a setting button 87. The setting value is changed by selecting the number of the optimum test print 100. Thus, even if the operator is unfamiliar with the structure of the apparatus, the operator can easily change the setting.

The setting value may be changed relative to not only the selected magazine ID but also any magazine ID. In this case, the magazine ID of which the setting is desired to be changed is selected by clicking an ID selection box 88. And then, the desired values are selected by clicking selection boxes 89 to 92 for selecting T2, T3, P1 and P5. Incidentally, optional values maybe inputted by the operator. Moreover, the test print 100 may be prepared on the basis of the selected or inputted setting values. After the selection, by clicking a setting button 93, the setting value corresponding to the selected magazine ID is recorded in the RAM 71 to change the setting value.

A value of a current flowing in the pulse motor 55 is also changeable. A motor-current selection box 94 is clicked to select a desired value from plural values. And then, the changed setting value is recorded in the RAM 71 by clicking a setting button 95.

The mechanism for moving the nip roller is not limited to the above embodiment. For example, it is possible to employ the mechanism shown in FIGS. 10 and 11. In this embodiment, an upstream nip roller 111 and a downstream nip roller 112 are vertically moved by rotating a cam unit 113 to nip the recording-paper sheet with a capstan roller, which is not shown, and to release the nip of the recording-paper sheet.

The cam unit 113 comprises a drive cam 115, a first cam 116 and a second cam 117, which are disposed in an axial direction of the nip rollers 111 and 112. A timing belt 120 is laid between the drive cam 115 and two pulleys 118 and 119. Upon driving a pulse motor 121 connected to the pulley 118, the timing belt 120 is moved to rotate the drive cam 115 around a rotary shaft in a counterclockwise direction. At this time, the first cam 116 and the second cam 117 fixed to the drive cam 115 are rotated in the counterclockwise direction.

Peripheral surfaces of the first cam 116 and the second cam 117 respectively abut on first and second cam followers 123 and 124 urged toward the cam unit 113. The first cam follower 123 and the upstream nip roller 111 are supported by a base member 125 and are capable of revolving around a rotary shaft 125a. Similarly, the second cam follower 124 and the downstream nip roller 112 supported by a base member 126 are capable of revolving around a rotary shaft 126a.

When the pulse motor 121 is driven to rotate the cam unit 113 in the counterclockwise direction, the first cam follower 123 moves in a radial direction of the cam unit 113, abutting on the first cam 116. In association with this movement, the upstream nip roller 111 moves between a nip position for nipping the recording-paper sheet with the capstan roller, which is not shown, and a release position for separating from the capstan roller. Similarly, the second cam follower 124 moves, abutting on the second cam 117, so that the downstream nip roller 112 moves between the nip position and the release position.

Also in the moving mechanism having this kind of the structure, the nipping/releasing timing of the nip rollers 111 and 112 are regulated by changing the values of T2 and T3. In doing so, the density-unevenness properties may be improved.

The above embodiments are described with the feeding mechanism in which two nip rollers are moved by using the sole pulse motor. The present invention, however, may be applied to another feeding mechanism in which pulse motors for driving the respective nip rollers are provided.

Although the present invention has been fully described by way of the preferred embodiments thereof with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein.