U.S. patent application number 13/393211 was filed with the patent office on 2012-11-08 for clamping device and printer.
This patent application is currently assigned to FUJIFILM CORPORATION. Invention is credited to Yasunobu Kayanuma.
Application Number | 20120280447 13/393211 |
Document ID | / |
Family ID | 46878919 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120280447 |
Kind Code |
A1 |
Kayanuma; Yasunobu |
November 8, 2012 |
CLAMPING DEVICE AND PRINTER
Abstract
A sheet 3 is caught between a clamper 15 and a platen drum 10 at
its sheet front end portion. The clamper 15 is provided with a
pressing member 32 with elasticity, and the pressing member 32 has
two projections 32b. During conveyance, a pressing surface 32a
tightly comes into contact with the front end portion of the sheet
3, while each projection 32b is elastically deformed and
compressed. When correcting skew of the sheet 3, the clamper 15 is
turned, while only the projections 32b press the front end portion
of the sheet 3.
Inventors: |
Kayanuma; Yasunobu;
(Saitama, JP) |
Assignee: |
FUJIFILM CORPORATION
Tokyo
JP
|
Family ID: |
46878919 |
Appl. No.: |
13/393211 |
Filed: |
November 4, 2011 |
PCT Filed: |
November 4, 2011 |
PCT NO: |
PCT/JP2011/075419 |
371 Date: |
February 28, 2012 |
Current U.S.
Class: |
271/228 ;
271/272 |
Current CPC
Class: |
B65H 9/08 20130101; B65H
2511/242 20130101; B65H 2701/1311 20130101; B41J 13/223 20130101;
B65H 2511/232 20130101; B65H 2404/144 20130101; B65H 7/08 20130101;
B65H 2511/232 20130101; B65H 9/04 20130101; B65H 2701/1311
20130101; B65H 2511/514 20130101; B65H 2220/11 20130101; B65H
2220/01 20130101; B65H 2220/02 20130101; B65H 2220/03 20130101;
B65H 2511/242 20130101; B65H 5/062 20130101 |
Class at
Publication: |
271/228 ;
271/272 |
International
Class: |
B65H 9/00 20060101
B65H009/00; B65H 7/02 20060101 B65H007/02; B65H 5/06 20060101
B65H005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2011 |
JP |
2011-064069 |
Claims
1. A clamping device comprising: a clamper having a pressing member
with elasticity, for catching a part of a lenticular sheet between
said pressing member and a support member for supporting at least a
part of said lenticular sheet; a clamper shifting mechanism for
shifting said damper among a retracted position, a first catching
position, and a second catching position, said pressing member
being away from said support member in said retracted position,
said pressing member pressing said part of said lenticular sheet so
as to prevent a slip of said lenticular sheet from said pressing
member and said support member in said first catching position,
said pressing member pressing said part of said lenticular sheet so
as to prevent a slip of said lenticular sheet from said pressing
member and allow a slip of said lenticular sheet from said support
member in said second catching position; a clamper turning
mechanism for turning said clamper around a turning axis orthogonal
to said lenticular sheet; and a controller, wherein when turning
said lenticular sheet being caught, said controller controls said
clamper shifting mechanism and said clamper turning mechanism so as
to set said clamper in said second catching position and turn said
clamper; when fixing said lenticular sheet on said support member,
said controller controls said clamper shifting mechanism so as to
set said clamper in said first catching position.
2. The clamping device as recited in claim 1, wherein said pressing
member has a plurality of projections formed in a pressing surface
faced to said support member; said first catching position denotes
a position in which said pressing surface is pressed against said
part of said lenticular sheet while compressing each of said
projections, to catch said part of said lenticular sheet between
said pressing surface and said support member; and said second
catching position denotes a position in which each of said
projections is pressed against said part of said lenticular sheet
with a compression value of each of said projections lower than
that of said first catching position, to catch said part of said
lenticular sheet between each of said projections and said support
member.
3. The clamping device as recited in claim 2, wherein a size of
said projection is in accordance with a distance from said turning
axis, and in said second catching position, an area at which said
projection contacts with said lenticular sheet differs in
accordance with said distance from said turning axis.
4. The clamping device as recited in claim 2, wherein out of a
surface area of said support member, at least an area faced to said
projection plus a movable area of said projection by said clamper
turning mechanism are allocated to a non-formation area, and a
remaining area is allocated to a formation area, and an elastic
layer having elasticity is formed in said formation area to make a
coefficient of friction in said non-formation area smaller than
that in said formation area.
5. The clamping device as recited in claim 4, wherein said
formation area includes a portion of said support member faced to
said pressing surface, such that said part of said lenticular sheet
is caught between said pressing surface and said elastic layer when
said damper is in said first catching position.
6. A printer having a printing section that conveys in a sub scan
direction a lenticular sheet having a plurality of lenses formed in
a front surface of said lenticular sheet, and sequentially prints
on a back surface of said lenticular sheet a plurality of stripe
images parallel to a main scan direction orthogonal to said sub
scan direction, said printer comprising: a platen for supporting
said lenticular sheet and moving said lenticular sheet in said sub
scan direction; a clamper having a pressing member with elasticity,
for pressing a sheet end portion of said lenticular sheet against
said platen to catch said sheet end portion between said clamper
itself and said platen; a clamper shifting mechanism for shifting
said clamper among a retracted position, a first catching position,
and a second catching position, said pressing member being away
from said platen in said retracted position, said pressing member
pressing said sheet end portion so as to prevent a slip of said
lenticular sheet from said pressing member and said platen in said
first catching position, said pressing member pressing said sheet
end portion so as to prevent a slip of said lenticular sheet from
said pressing member and allow a slip of said lenticular sheet from
said platen in said second catching position; a skew detection
section for detecting skew of said lenticular sheet; a damper
turning mechanism for turning said clamper around a turning axis
orthogonal to said lenticular sheet; and a controller, wherein when
correcting said skew of said lenticular sheet with respect to said
main scan direction, said controller controls said damper shifting
mechanism and said clamper turning mechanism to set said clamper in
said second catching position and turn said clamper based on a
detection result of said skew detection section; and when conveying
said lenticular sheet in said sub scan direction, said controller
controls said clamper shifting mechanism to set said clamper in
said first catching position while said platen is moved in said sub
scan direction.
7. The printer as recited in claim 6, wherein said pressing member
has a plurality of projections formed in a pressing surface faced
to said platen; said first catching position denotes a position in
which said pressing surface is pressed against said sheet end
portion while compressing each of said projections, to catch said
sheet end portion between said pressing surface and said platen:
and said second catching position denotes a position in which each
of said projections is pressed against said sheet end portion with
a compression value of each of said projections lower than that of
said first catching position, to catch said sheet end portion
between each of said projections and said platen.
8. The printer as recited in claim 7, wherein a size of said
projection is in accordance with a distance from said turning axis,
and in said second catching position, an area at which said
projection contacts with said sheet end portion differs in
accordance with said distance from said turning axis.
9. The printer as recited in claim 7, wherein out of a surface area
of said platen, at least an area faced to said projection plus a
movable area of said projection by said clamper turning mechanism
are allocated to a non-formation area, and a remaining area is
allocated to a formation area, and an elastic layer having
elasticity is formed in said formation area, and a coefficient of
friction is smaller in said non-formation area than that in said
formation area.
10. The printer as recited in claim 9, wherein said formation area
includes a portion of said platen faced to said pressing surface,
such that said sheet end portion is caught between said pressing
surface and said elastic layer when said clamper is in said first
catching position.
11. The printer as recited in claim 6, wherein said platen
comprises a rotatable platen drum on which said lenticular sheet is
wound.
12. The printer as recited in claim 6, wherein a sheet front end
portion of said lenticular sheet is caught between said clamper and
said platen.
13. The clamping device as recited in claim 3, wherein out of a
surface area of said support member, at least an area faced to said
projection plus a movable area of said projection by said clamper
turning mechanism are allocated to a non-formation area, and a
remaining area is allocated to a formation area, and an elastic
layer having elasticity is formed in said formation area to make a
coefficient of friction in said non-formation area smaller than
that in said formation area.
14. The printer as recited in claim 8, wherein out of a surface
area of said platen, at least an area faced to said projection plus
a movable area of said projection by said damper turning mechanism
are allocated to a non-formation area, and a remaining area is
allocated to a formation area, and an elastic layer having
elasticity is formed in said formation area, and a coefficient of
friction is smaller in said non-formation area than that in said
formation area.
15. The printer as recited in claim 7. wherein said platen
comprises a rotatable platen drum on which said lenticular sheet is
wound.
16. The printer as recited in claim 8, wherein said platen
comprises a rotatable platen drum on which said lenticular sheet is
wound.
17. The printer as recited in claim 9, wherein said platen
comprises a rotatable platen drum on which said lenticular sheet is
wound.
18. The printer as recited in claim 10, wherein said platen
comprises a rotatable platen drum on which said lenticular sheet is
wound.
19. The printer as recited in claim 2, wherein a sheet front end
portion of said lenticular sheet is caught between said clamper and
said platen.
20. The printer as recited in claim 3, wherein a sheet front end
portion of said lenticular sheet is caught between said clamper and
said platen.
Description
TECHNICAL FIELD
[0001] The present invention relates to a clamping device for
correcting skew of a lenticular sheet, and a printer for printing
an image on the lenticular sheet.
BACKGROUND ART
[0002] Lenticular 3D photography in which a 3D image is observed
with naked eyes with use of a lenticular sheet having a lot of
lenses in an approximately semi-cylindrical shape arranged side by
side is widely known. In the lenticular 3D photography, for
example, each of an R viewpoint image and an L viewpoint image
captured from two viewpoints of right and left is split into narrow
stripes (lines), and the stripe images of the R viewpoint image and
the stripe images of the L viewpoint image are alternately disposed
on a back surface of the lenticular sheet, so as to locate the two
adjoining stripe images under the single lens. Since the right and
left eyes see through each lens the R and L viewpoint images with
parallax, respectively, the 3D image is realized. It is also known
that an N (N is three or more) number of viewpoint images are
captured and split into narrow stripes, and an N number of stripe
images are arranged behind the single lens to further improve a
stereoscopic effect.
[0003] There are two types of lenticular 3D photography, including
the type of overlaying the lenticular sheet on a sheet on which the
stripe images are printed, and the type of printing the stripe
images on a back surface of the lenticular sheet. In the case of
printing the stripe images on the back surface of the lenticular
sheet by using a printer, the lenticular sheet is intermittently
conveyed in a sub scan direction. Just after each intermittent
conveyance, a print head is actuated to print the stripe images
extending in a main scan direction on the back surface of the
lenticular lens one by one. Thus, at least the two kinds of
viewpoint images having parallax are printed on the back surface of
the lenticular sheet (refer to patent documents 1 and 2).
[0004] There is known a printer in which the stripe images are
printed on a sheet and then this sheet is glued on the lenticular
sheet (refer to patent document 3). This printer requires a
mechanism for correctly positioning the lenticular sheet relative
to the stripe images and gluing the sheets. For this reason, the
printer of the type of printing the stripe images directly on the
back surface of the lenticular lens has size and cost
advantages.
[0005] By the way, when the plural viewpoint images are printed on
the back surface of the lenticular sheet, the lenticular sheet is
sometimes conveyed with inclination. This inclination is called
skew. In this case, since the stripe images are printed in such a
state that a longitudinal direction of the lens does not coincide
with the main scan direction, print quality significantly
deteriorates. In order to prevent the deterioration of the print
quality caused by the skew of the lenticular sheet, various
techniques are conventionally devised.
[0006] Patent document 1 describes a printer in which an optical
sensor provided in the vicinity of a print head detects the
position of the lenses, and the print position of the stripe images
is adjusted based on a position detection result. Even if the
lenticular sheet is skewed, the print position of the stripe images
can be adjusted in accordance with the skew.
[0007] Patent document 2 describes a printer for correcting the
skew of the lenticular sheet in advance. In this printer, an
inclination angle of the longitudinal direction of the lens with
respect to the main scan direction is detected. A conveyance amount
in the sub scan direction is made different between right and left
sides in accordance with a detection result, so that the lenticular
sheet is turned around an axis orthogonal to its conveyance surface
to correct the skew.
[0008] On the other hand, there are known two conveyance types of
the printer, a linear conveyance type and a platen drum type. When
printing a color image, for example, in the former type, a print
sheet is conveyed on a linear conveyance path, and the color image
is printed by a color sequential method during this reciprocating
conveyance. In the latter type, the platen drum on which the print
sheet is wound is rotated, and the color image is printed while the
print sheet is conveyed in a rotation direction of the platen drum
(refer to paten document 4, for example) . In the former type,
since evacuation space of the print sheet is required before and
behind the print head, the printer tends to be large in size. In
the latter type, on the other hand, no evacuation space is
required, and the print head and a sheet ejecting mechanism can be
laid out around the platen drum, so this type of printer has an
advantage in size reduction.
PRIOR ART DOCUMENTS
Patent Documents
[0009] Patent document 1: Japanese Patent Laid-Open Publication No.
2007-76084 Patent document 2: Japanese Patent Laid-Open Publication
No. 8-137034 Patent document 3: Japanese Patent Laid-Open
Publication No. 7-219084 Patent document 4: Japanese Patent
Laid-Open Publication No. 61-128677
SUMMARY OF INVENTION
Problems to be Solved by the Invention
[0010] By the way, in the case of adjusting the print position of
the stripe image, as described in the patent document 1, there is a
problem that if the skew of the lenticular sheet is large,
distortion of the viewpoint image printed on the reticular sheet
becomes large, and causes deterioration in print quality. The
printer for printing the stripe images on the lenticular sheet can
get the size advantage by adopting the platen drum type. However,
since the conveyance amount cannot be made different between the
right and left sides, in contrast to the patent document 2, the
skew of the lenticular sheet cannot be corrected. Furthermore, if
the platen drum is turned around an axis orthogonal to its rotation
axis with the aim of correcting the skew of the lenticular sheet,
the distance between the print head and the platen drum becomes
uneven. This causes deterioration in image quality.
[0011] A main object of the present invention is to provide a
clamping device and a printer that can suitably correct skew of a
lenticular sheet without causing image distortion. Another object
of the present invention is to provide the printer that has simple
structure and small size.
Means for Solving the Problems
[0012] A clamping device according to the present invention
includes a clamper, a clamper shifting mechanism, a clamper turning
mechanism, and a controller. The clamper has a pressing member with
elasticity, and catches a part of a lenticular sheet between this
pressing member and a support member. The support member supports
at least a part of the lenticular sheet. The clamper shifting
mechanism shifts the clamper among a retracted position, a first
catching position, and a second catching position. In the retracted
position, the pressing member is away from the support member. In
the first catching position, the pressing member presses the part
of the lenticular sheet so as to prevent a slip of the lenticular
sheet from the pressing member and the support member. In the
second catching position, the pressing member presses the part of
the lenticular sheet so as to prevent a slip of the lenticular
sheet from the pressing member and allow a slip of the lenticular
sheet from the support member. The clamper turning mechanism turns
the clamper around a turning axis orthogonal to the lenticular
sheet. To turn the caught lenticular sheet, the controller controls
the clamper shifting mechanism and the clamper turning mechanism so
as to turn the clamper set in the second catching position. To fix
the lenticular sheet on the support member, the controller controls
the clamper shifting mechanism so as to set the clamper in the
first catching position.
[0013] The pressing member preferably has a plurality of
projections formed in a pressing surface faced to the support
member. In the first catching position, the pressing surface is
pressed against the part of the lenticular sheet while compressing
each projection, so the part of the lenticular sheet is caught
between the pressing surface and the support member. In the second
catching position, each projection is pressed against the part of
the lenticular sheet with a compression value of each projection
lower than that of the first catching position, so the part of the
lenticular sheet is caught between each projection and the support
member.
[0014] The size of the projection is preferably in accordance with
a distance from the turning axis. In the second catching position,
an area at which the projection contacts with the lenticular sheet
preferably differs in accordance with the distance from the turning
axis.
[0015] It is preferable that out of a surface area of the support
member, at least an area faced to each projection plus a movable
area of each projection by the clamper turning mechanism are
allocated to a non-formation area, and a remaining area is
allocated to a formation area, and an elastic layer having
elasticity is formed in the formation area to make a coefficient of
friction in the non-formation area smaller than that in the
formation area.
[0016] The formation area preferably includes a portion of the
support member faced to the pressing surface, such that the part of
the lenticular sheet is caught between the pressing surface and the
elastic layer when the clamper is in the first catching
position.
[0017] A printer according to the present invention, which conveys
in a sub scan direction a lenticular sheet having a plurality of
lenses formed in a front surface of the lenticular sheet and
sequentially prints on a back surface of the lenticular sheet a
plurality of stripe images parallel to a main scan direction
orthogonal to the sub scan direction, includes a platen, a clamper,
a clamper shifting mechanism, a skew detection section, a clamper
turning mechanism, and a controller. The platen supports the
lenticular sheet and moves the lenticular sheet in the sub scan
direction. The clamper has a pressing member with elasticity, and
presses a sheet end portion of the lenticular sheet against the
platen to catch the sheet end portion between the clamper itself
and the platen. The clamper shifting mechanism shifts the clamper
among a retracted position, a first catching position, and a second
catching position. In the retracted position, the pressing member
is away from the platen. In the first catching position, the
pressing member presses the sheet end portion of the lenticular
sheet so as to prevent a slip of the lenticular sheet from the
pressing member and the platen. In the second catching position,
the pressing member presses the sheet end portion of the lenticular
sheet so as to prevent a slip of the lenticular sheet from the
pressing member and allow a slip of the lenticular sheet from the
platen. The skew detection section detects skew of the lenticular
sheet. The clamper turning mechanism turns the clamper around a
turning axis orthogonal to the lenticular sheet. To correct the
skew of the lenticular sheet with respect to the main scan
direction, the controller controls the clamper shifting mechanism
and the clamper turning mechanism to turn the clamper set in the
second catching position based on a detection result of the skew
detection section. To convey the lenticular sheet in the sub scan
direction, the controller controls the clamper shifting mechanism
and sets the clamper in the first catching position while the
platen is moved in the sub scan direction.
[0018] The pressing member preferably has a plurality of
projections formed in a pressing surface faced to the platen. In
the first catching position, the pressing surface is pressed
against the sheet end portion while compressing each projection, to
catch the sheet end portion between the pressing surface and the
platen. In the second catching position, each projection is pressed
against the sheet end portion with a compression value lower than
that of the first catching position, to catch the sheet end portion
between each projection and the platen.
[0019] The size of the projection is preferably in accordance with
a distance from the turning axis. In the second catching position,
an area at which the projection contacts with the lenticular sheet
preferably differs in accordance with the distance from the turning
axis.
[0020] Out of a surface area of the platen, at least an area faced
to each projection plus a movable area of each projection by the
clamper turning mechanism are preferably allocated to a
non-formation area, while a remaining area is preferably allocated
to a formation area. It is preferable that an elastic layer having
elasticity is formed in the formation area, and a coefficient of
friction is smaller in the non-formation area than that in the
formation area.
[0021] The formation area preferably includes a portion of the
platen faced to the pressing surface, such that the sheet end
portion is caught between the pressing surface and the elastic
layer, when the clamper is in the first catching position.
[0022] The platen is preferably a rotatable platen drum on which
the lenticular sheet is wound.
[0023] A sheet front end portion of the lenticular sheet is
preferably caught between the clamper and the platen.
Effect of the Invention
[0024] According to the present invention, it is possible to
correct the skew of the lenticular sheet with simple structure.
Also, printing is carried out with contributing to simplified
structure and reduced size without occurrence of deterioration in
image quality, such as distortion of an image.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is an explanatory view showing an outline of a
printer to which the present invention is applied.
[0026] FIG. 2 is a perspective view of a lenticular sheet.
[0027] FIG. 3 is an explanatory view showing a state of peeling the
lenticular sheet by a peeling claw.
[0028] FIG. 4 is a perspective view showing a bottom side of a
clamper;
[0029] FIG. 5A is an explanatory view showing a state of the
clamper in a retracted position.
[0030] FIG. 5B is an explanatory view showing a state of the
clamper in a first catching position.
[0031] FIG. 5C is an explanatory view showing a state of the
clamper in a second catching position.
[0032] FIG. 6 is an explanatory view of a platen drum showing an
area having an elastic layer and an area without having the elastic
layer.
[0033] FIG. 7 is an explanatory view showing the positional
relation between a pressing surface and projections of the clamper
and the area without having the elastic layer.
[0034] FIG. 8 is an explanatory view showing an arrangement of lens
sensors relative to the lenticular sheet.
[0035] FIG. 9 is a perspective view of a clamper unit.
[0036] FIG. 10 is a perspective view showing a rear end clamp and
an open/close mechanism thereof.
[0037] FIG. 11 is a flowchart showing a procedure from skew
correction to printing.
[0038] FIG. 12 is an explanatory view of an embodiment in which
only areas faced to the projections plus movable areas of the
projections are allocated to non-formation areas of the elastic
layer.
[0039] FIG. 13 is an explanatory view of another embodiment in
which the projections are changed in size in accordance with
distance from a turning axis of the clamper.
DESCRIPTION OF INVENTION
[0040] In FIG. 1, a printer 2 prints a parallax image (a collection
of viewpoint images) for observing a 3D image on a back surface of
a lenticular sheet (hereinafter simply called sheet) 3 by a
sublimation method. This printer 2 converts two viewpoint images
into six viewpoint images, and splits the six viewpoint images into
many stripe images, and prints the stripe images on the sheet
3.
[0041] As shown in FIG. 2, many lenses 4 in the shape of an
approximately cylinder (cylindrical) are arranged on the side of a
front surface of the sheet 3, and the back surface of the sheet 3
is flat, as is well known. Each lens 4 extends in a main scan
direction. The back surface of the sheet 3 is virtually partitioned
into image areas 5 in accordance with the individual lenses 4, and
the single image area 5 corresponds to the single lens 4. Each
image area 5 is partitioned in an arrangement direction of the
lenses 4 in accordance with the number of the viewpoint images.
[0042] In this embodiment, the image area 5 is partitioned into
first to sixth small areas 5a to 5f. The stripe images, into which
the six viewpoint images are split into stripes, are printed on the
first to sixth small areas 5a to 5f. The small areas 5a to 5f
correspond to the first to sixth viewpoint images on a one-by-one
basis. In this embodiment, each of the small areas 5a to 5f has a
width (length in a sub scan direction) of approximately 40 .mu.m,
and a single line has a width of approximately 20 .mu.m. Thus, for
example, two adjoining lines of the first viewpoint image are
printed side by side on the first small area 5a as the single
stripe image.
[0043] As shown in FIG. 1, the printer 2 is provided with a paper
feed cassette 9. The paper feed cassette 9 contains a stack of
sheets 3. In printing, a paper feed mechanism (not shown) supplies
the single sheet 3 from the paper feed cassette 9 to a feeding path
6. The sheet 3 is conveyed through the feeding path 6 with the
lenses 4 facing down in the arrangement direction (sub scan
direction) of the lenses 4. Note that, the sheet 3 may be manually
inserted into the feeding path 6 instead.
[0044] In the feeding path 6, there are provided a feeding roller
pair 7 and a sensor section 8 in this order from an upstream side
(on the side of the paper feed cassette 9), and a platen drum 10 is
disposed downstream from the feeding path 6. The feeding path 6
extends in a tangential direction of an outer circumference of the
platen drum 10, so the sheet 3 supplied from the feeding path 6 is
fed to an outer circumferential surface of the platen drum 10.
[0045] The feeding roller pair 7 is constituted of a capstan roller
7a rotated by a motor 12, and a pinch roller 7b that is shiftable
between a nip position for nipping the sheet 3 between itself and
the capstan roller 7a and a release position being distant from the
sheet 3. The feeding roller pair 7 nips the sheet and conveys the
sheet 3 to the platen drum 10 by the rotation of the capstan roller
7a.
[0046] The platen drum 10 is rotatably supported by a shaft 10a
parallel to the main scan direction, and rotated by a motor 14. The
rotation direction of the motor 14 is changeable, and hence the
platen drum 10 is rotated in one of a forward direction indicated
by an arrow A and a reverse direction opposite thereto.
[0047] In printing, the sheet 3 is wound onto the outer
circumferential surface 10b of the platen drum 10. The platen drum
10 conveys the sheet 3 in the sub scan direction by its rotation.
The sheet 3 is wound in such an orientation that the lenses 4 face
to a platen drum side and the arrangement direction of the lenses 4
corresponds with a circumferential direction (sub scan direction)
of the platen drum 10.
[0048] A clamper 15, a clamper shifting mechanism 16, and a clamper
turning mechanism 17 compose a clamp unit. The clamper 15 catches a
front end portion (hereinafter called sheet front end portion) of
the sheet 3 between itself and the outer circumferential surface
10b. The clamper 15 is integrated into the platen drum 10, and
rotated integrally with the platen drum 10 to the sub scan
direction. In this embodiment, the platen drum 10 functions as a
support member. The platen drum 10 and the motor 14 compose a
conveyance mechanism for conveying the sheet 3 in the sub scan
direction.
[0049] The clamper shifting mechanism 16 shifts the clamper 15 in a
radial direction of the platen drum 10. By the clamper shifting
mechanism 16, the clamper 15 is shifted between a catching position
for catching the sheet front end portion between itself and the
outer circumferential surface 10b and a retracted position for
releasing the catch. The catching position includes a first
catching position for tightly catching the sheet front end portion,
and a second catching position for catching the sheet front end
portion more loosely than that in the first catching position.
[0050] The clamper turning mechanism 17 turns the clamper 15 around
a turning axis orthogonal to the surface of the sheet 3. The
clamper 15 is turned while catching the sheet 3, so that the sheet
3 is turned by an arbitrary angle to correct its skew. In this
embodiment, the radial direction of the platen drum 10 coincides
with a direction orthogonal to the sheet 3 wound on the platen drum
10.
[0051] In the outer circumference of the platen drum 10, a thermal
head 18 and a peeling claw 19 are disposed. The thermal head 18 has
at its bottom two heating element arrays 18a, each of which is
composed of a lot of heating elements linearly arranged in the main
scan direction. The provision of the two heating element arrays 18a
adjoining to each other makes it possible to print the single
stripe image (two lines) at a time. Then, conveyance of the sheet 3
for six times in the sub scan direction by the width of the small
area makes it possible to print the single image area 5. The length
of each heating element array 18a in the main scan direction is
slightly longer than the width (length in the main scan direction)
of a print area of the sheet 3.
[0052] The thermal head 18 is shifted between a pressing position
for pressing a print film 21 against the back surface of the sheet
3 in a state of overlaying the print film 21 on the back surface of
the sheet 3 on the platen drum 10 and a retracted position for
retracting upward from the pressing position. The print film 21
includes an image receptor film, a yellow ink film, a magenta ink
film, a cyan ink film, and a back layer film. The size of each film
is approximately the same as that of the sheet 3. These films are
joined side by side to compose a film set for the single sheet. The
print film 21 is fed from one of spools to the other and wound up
thereto, in synchronization with the conveyance of the sheet 3.
[0053] The image receptor film forms on the back surface of the
sheet 3 an image receptor layer (under layer) that is stained with
color ink from the ink films. When the image receptor film is
heated by the thermal head 18 while being overlaid on the back
surface of the sheet 3, the transparent image receptor layer is
transferred to the back surface of the sheet 3.
[0054] The yellow, magenta, and cyan ink films are well known
dye-sublimation ink films. When each ink film is heated by the
thermal head 18 while being overlaid on the image receptor layer
formed on the back surface of the sheet 3, the ink sublimates and
is transferred to the image receptor layer. The amount of adhesion
of the ink increases or decreases in accordance with a heating
value of the thermal head 18, and this facilitates representation
of a halftone. Note that, by using a black ink film, the printing
with four colors may be carried out.
[0055] The back layer film transfers a white back layer to the
image, when being heated by the thermal head 18 in a state of being
overlaid on the image printed on the sheet 3. This back layer
reflects light, and allows observation of the bright and sharp
color 3D image.
[0056] A head driver 22 composes a printing section 23 together
with the thermal head 18. The head driver 22 drives every heating
element of the thermal head 18. In forming the image receptor layer
and the back layer, the head driver 22 drives the thermal head 18
such that every heating element generates the same heating value.
This heating value is set at a value necessary for transferring the
image receptor layer and the back layer. In printing an image with
use of the ink films, the head driver 22 prints a full color image
by a three-color field sequential printing. In this case, each
heating element is heated based on image data of the six viewpoint
images, to obtain ink density corresponding to the image data.
[0057] The image data of the image to be printed is inputted to a
controller 24. The inputted image data is the viewpoint images from
two viewpoints, for example. The controller 24 converts the image
data from the two viewpoints into image data from six viewpoints.
The converted image data from six viewpoints is sent to the head
driver 22.
[0058] The peeling claw 19 peels the printed sheet 3 from the
platen drum 10, and guides the sheet 3 into a cutter unit 25. The
peeling claw 19 is disposed in the middle of the sheet 3 in the
width direction, and swingable between a retracted position in
which a tip of the peeling claw 19 is away from the outer
circumferential surface 10b as shown in FIG. 1 and a peeling
position in which the tip makes contact with the outer
circumferential surface 10b as shown in FIG. 3. When the platen
drum 10 is rotated in the reverse direction in a state of setting
the peeling claw 19 in the peeling position, the peeling claw 19
scoops the sheet from its rear end and guides the sheet 3 into the
cutter unit 25. The cutter unit 25 cuts off margins, that is, the
sheet front end portion and a rear end portion of the sheet 3
(hereinafter called sheet rear end portion) , which are caught by
the clamper 15 and rear end clamps 27, respectively, and no image
is printed thereto. Then, the cutter unit 25 ejects the cut sheet 3
from the printer.
[0059] Note that, the position of the peeling claw 19 is adjusted
such that when the peeling claw 19 scoops the rear end of the sheet
3 by the reverse rotation of the platen drum 10 and the platen drum
10 is further rotated by a small amount in the reverse direction,
the rotation position of the platen drum 10 is set in a standby
position, as described later, for actuating the clamper 15. Thus,
after releasing the catch of the sheet 3, a conveyance mechanism
contained in the cutter unit 25 can convey the sheet 3.
[0060] On the outer circumference of the platen drum 10, a
plurality of guide rollers 26 are disposed. When the sheet 3 is
wound onto the platen drum 10, these guide rollers 26 are pressed
against the platen drum 10 so as to catch the sheet 3 therebetween.
Thus, until the rear end clamps 27 catch the sheet rear end
portion, the guide rollers 26 prevent the sheet 3 from floating
from the outer circumferential surface 10b due to solidity of the
sheet 3 itself. Note that, for example, the guide rollers 26 are
shiftable in the radial direction of the platen drum 10, so the
guide rollers 26 do not interfere with the moving clamper 15.
[0061] The rear end clamps 27 are operated by an open/close
mechanism 28, and are shifted between a catching position for
catching the sheet 3 and a retracted position for releasing the
catch. The rear end clamps 27 catch the sheet rear end portion
between themselves and the platen drum 10, in order to prevent the
sheet 3 from floating from the outer circumferential surface 10b
due to the solidity of the sheet 3 itself during printing. These
rear end clamps 27 are rotated integrally with the platen drum
10.
[0062] The controller 24 controls each part of the printer 2
including the motors 12 and 14, the peeling claw 19, the open/close
mechanism 28, and the like in addition to the clamper shifting
mechanism 16, the clamper turning mechanism 17, the head driver 22,
and the like.
[0063] FIG. 4 shows the clamper 15 in such a posture that its
bottom surface (side to face to the platen drum) faces upward. This
clamper 15 is constituted of a base plate 31 having solidity and a
pressing member 32 integrally provided on a lower surface of the
base plate 31. The base plate 31, being a rectangular plate, has a
length approximately the same as that of the sheet 3 in the main
scan direction, and an appropriate width in the sub scan direction.
The pressing member 32 has the same size as that of the base plate
31. In the pressing member 32, a pair of projections 32b is formed
in a flat pressing surface 32a. The pressing member 32 is made of
an elastic material having a high coefficient of friction. Such
material includes rubber, for example. The projections 32b are
integrally formed of the same material as that of the pressing
member 32, but may be formed of a material different from that of
the pressing member 32 as long as the material has elasticity and a
high coefficient of friction.
[0064] The protruding amount (height) of the projections 32b is on
the order of 0.1 to 0.3 mm. The distance between the pair of
projections 32b is set narrower than the width of the sheet 3, and
the projections 32b concurrently come into contact with the sheet
3. For convenience in explanation, each projection 32b is
exaggerated in FIG. 4 and other drawings.
[0065] As shown in FIG. 5A, in the retracted position, the clamper
15 makes an appropriate gap between the projections 32b and the
outer circumferential surface 10b of the platen drum 10. This
allows the sheet 3 fed from the feeding path 6 to get into space
between the projections 32b and the outer circumferential surface
10b, and the sheet 3 to be pulled out of the space between the
projections 32b and the outer circumferential surface 10b.
[0066] As shown in FIG. 5B, in the first catching position, the
clamper 15 presses the sheet front end portion with the entire
pressing surface 32b. In this first catching position, each
projection 32b is pressed against the sheet front end portion, and
elastically deformed and compressed. By catching the sheet front
end portion with the entire pressing surface 32a, as described
above, the sheet front end portion is tightly caught without
slipping off from the pressing member 32 and the outer
circumferential surface 10b. While the sheet 3 is conveyed, the
clamper 15 is set in the first catching position.
[0067] As shown in FIG. 5C, in the second catching position, the
clamper 15 is slightly shifted to the side of the retracted
position, as compared to the first catching position. Thus, the
pressing surface 32a is away from the sheet 3, and each projection
32b is compressed with a compression amount less than that of the
first catching position. The sheet front end portion is pressed and
caught only by the projections 32b. This catching position allows
the sheet front end portion to slip off from the outer
circumferential surface 10b, while prevents the sheet front end
portion from slipping out of the projections 32b. When correcting
the skew of the sheet 3, the clamper 15 is set in the second
catching position. When the clamper 15 is set in the second
catching position and turned, the sheet 3 is turned by following
the turn of the clamper 15.
[0068] As shown in FIG. 6, an elastic layer 35 having elasticity is
formed on a surface of a drum body 34 made of metal, for example.
This elastic layer 35 is provided with the aim of preventing a
scratch on the sheet 3 caused by slipping by dint of tight contact
with the sheet 3, improving contact of the thermal head 18 with the
sheet 3, and the like. Such elastic layer 35 is formed by spray
coating of the rubber, for example.
[0069] The formation of the elastic layer 35 as described above on
the entire circumference of the platen drum 10 deteriorates a slip
between the sheet front end portion and the elastic layer 35. Thus,
even if the clamper 15 set in the second catching position is
turned, the sheet 3 could not be turned with following the turn of
the clamper 15 with precision.
[0070] Therefore, in the platen drum 10, a part of the outer
circumferential surface 10b is allocated to a non-formation area 36
in which no elastic layer 35 is formed, and the remaining part is
allocated to a formation area 37 in which the elastic layer 35 is
formed. The non-formation area 36 is situated in a portion facing
to the clamper 15. From the non-formation area 36, the surface of
the drum body 34, which has a lower coefficient of friction than
that of the surface of the elastic layer 35, is exposed.
[0071] As shown in FIG. 7, the non-formation area 36 is formed
across the entire width of the platen drum 10 in the main scan
direction, while is narrower than the width of the pressing surface
32a in the sub scan direction. A part of the outer circumferential
surface 10b that faces to the pressing surface 32a composes a part
of the formation area 37.
[0072] Since the elastic layer 35 is formed as described above,
when the clamper 15 is set in the second catching position, the
projections 32b press the sheet front end portion within the
non-formation area 36, even if the clamper 15 is in any turn
position. Thus, the sheet front end portion makes contact with the
metal surface of the platen drum 10, which has the low coefficient
of friction, at portions pressed by the projections 32b, so that
the sliding between the sheet front end portion and the outer
circumference 10b is not inhibited. On the other hand, when the
clamper 15 is in the first catching position, the pressing surface
32a tightly presses the sheet front end portion against the elastic
layer 35 (formation area 37) having the high coefficient of
friction to keep hold of the sheet. This prevents the slip of the
sheet 3 during conveyance in printing and the like.
[0073] The procedure of detecting skew of the sheet, turning the
clamper 15, and the like can be appropriately determined. In this
embodiment, the procedure consists of three steps including
judgment of an inclination direction, rough adjustment, and fine
adjustment. The skew of the sheet 3 is detected, while the sheet 3
is conveyed by the rotation of the platen drum 10. The skew
correction is carried out, when the conveyance of the sheet 3 is
stopped.
[0074] In FIG. 1, the sensor section 8 composes a skew detection
section for detecting the skew of the sheet 3 together with the
controller 24. The controller 24 judges the inclination direction
of the sheet 3 and an inclination angle .theta. of the sheet 3
based on a detection signal from the sensor section 8, and turns
the clamper 15 by controlling the clamper turning mechanism 17 so
as to correct the skew. The inclination direction refers to an
inclination direction of the lenses 4 in their longitudinal
direction with respect to the main scan direction. The inclination
angle .theta. refers to an inclination angle of the lenses 4 in
their longitudinal direction with respect to the main scan
direction.
[0075] The sensor section 8, as shown in FIG. 8, includes first to
third lens sensors 41 to 43 that are aligned in the main scan
direction. The lens sensors 41 to 43 are disposed so as not to have
equal distances therebetween (S1.noteq.S2, S2.noteq.S3,
S1.noteq.S3). Each of the lens sensors 41 to 43 is constituted of
an LED (light emitting diode) disposed under the sheet 3 and a
photosensor disposed oppositely to the LED above the sheet 3. The
photosensor receives detection light that has been emitted from the
LED and passed through the sheet 3, and outputs a detection signal
in accordance with the intensity of the detection light.
[0076] For example, the detection signal from each of the lens
sensors 41 to 43 gradually increases in a period from when the lens
sensor 41 to 43 faces to a boundary between the lenses 4 until when
the lens sensor 41 to 43 faces to a vertex of the lens 4, and
reaches its peak when the lens sensor 41 to 43 faces to the vertex.
After that, the detection signal gradually decreases, and is
changed again into the gradual increase when the lens sensor 41 to
43 faces to the boundary between the lenses 4. Note that, in this
embodiment, the sensor section 8 also detects the front end of the
sheet 3 during feeding, measures the pitch of the lenses 4, and the
like.
[0077] In the judgment of the inclination direction, a conveyance
length LA of the sheet 3 conveyed from the time when the detection
signal of the first lens sensor 41 reaches its peak during the
conveyance of the sheet 3 to the time when the detection signal of
the second lens sensor 42 reaches its peak thereafter is measured.
In other words, the conveyance length of the sheet 3 conveyed from
the time when the first lens sensor 41 detects the vertex of the
arbitrary lens 4 to the time when the second lens sensor 42 detects
the vertex of the lens 4 thereafter is measured. Note that, the
conveyance length can be obtained based on the number of drive
pulses supplied to the motor 14 being a drive source of the platen
drum 10, for example, but may be measured using an encoder rotating
together with the platen drum 10 or the like.
[0078] The distances of the first to third lens sensors 41 to 43
are determined and the large skew of the fed sheet 3 is prevented,
such that all of the following conditions are satisfied in a state
where the clamper 15 catches the fed sheet 3.
[0079] 1: When the inclination direction of the sheet 3 is a
clockwise direction (C.W. direction of FIG. 8), the first to third
lens sensors 41 to 43 detect the vertex of the identical lens 4 in
this order.
[0080] 2: The first to third lens sensors 41 to 43 do not detect
the vertexes of the different lenses 4 at the same time.
[0081] 3: When the inclination angle of the sheet 3 is the
clockwise direction, after the first lens sensor 41 detects the
vertex of the arbitrary lens 4, the second lens sensor 42 detects
the vertex of the identical lens 4.
[0082] On the above conditions, the inclination angle .theta. of
the sheet 3 is calculated by the following expression (1) based on
the conveyance length LA and the known distance S1 between the
first and second lens sensors 41 and 42. The inclination direction
of the sheet 3 is assumed to be the clockwise direction. Using the
calculated inclination angle .theta. and the known distance S3
between the first and third lens sensors 41 and 43, a predicted
value of a conveyance length LB conveyed to the time when the third
lens sensor 43 detects the vertex of the lens 4 identical to the
lens 4 that the first lens sensor 41 has detected is calculated by
the following expression (2).
.theta.=tan-1(LA/S1) (1)
LB=S3.times.tan.theta. (2)
[0083] After the calculation of the predicted value of the
conveyance length LB, the conveyance length and the detection
signal of the third lens sensor 43 from the time when the detection
signal of the first lens sensor 41 reaches its peak are monitored,
and the inclination direction is judged from the relation
therebetween. When the inclination direction of the sheet 3 is the
clockwise direction as being assumed, the detection signal of the
third lens sensor 43 reaches its peak in the vicinity of a position
corresponding to the conveyance length LB. On the other hand, when
the inclination direction of the sheet 3 is a counterclockwise
direction, the detection signal of the third lens sensor 43 does
not reach its peak in the vicinity of the position corresponding to
the conveyance length LB. Therefore, in a case where the detection
signal of the third lens sensor 43 reaches its peak in the vicinity
of the position corresponding to the conveyance length LB, the
inclination direction of the sheet 3 is judged to be the clockwise
direction. In the other case, the inclination direction of he sheet
3 is judged to be the counterclockwise direction.
[0084] The judgment of the counterclockwise direction, as described
above, is based on the premise that the above expressions (1) and
(2) do not hold when the actual inclination direction of the sheet
3 is the counterclockwise direction. More specifically, when the
inclination direction of the sheet 3 is the counterclockwise
direction, the conveyance length LA comes to be a length from the
time when the first lens sensor 41 detects the vertex of the lens 4
to the time when the second lens sensor 42 detects the vertex of
the next lens 4, so the expressions (1) and (2) do not hold.
[0085] After the judgment of the inclination direction, the rough
adjustment is carried out. When the judged inclination direction of
the sheet 3 is the clockwise direction, the inclination angle
.theta. that is calculated in the judgment of the inclination
direction from the expression (1) is set at a rough-adjustment
inclination angle, and the clamper 15 is turned by the
rough-adjustment inclination angle in the counterclockwise
direction. Accordingly, the inclination angle .theta. becomes
almost 0.degree..
[0086] On the other hand, when the judged inclination direction of
the sheet 3 is the counterclockwise direction, the distance to the
peak of the detection signal of the second lens sensor 42 nearest
to a criterion, which is the time when the detection signal of the
first lens sensor 41 reaches its peak, is calculated as a
conveyance length L1. Next, by substituting the conveyance length
L1 for the conveyance length LA into the above expression (1), the
rough-adjustment inclination angle is obtained. Then, the clamper
15 is turned by the rough-adjustment inclination angle in the
clockwise direction.
[0087] At this time, when the nearest peak of the detection signal
of the second lens sensor 42 is later than the peak of the
detection signal of the first lens sensor 41, the nearest peak
corresponds to the vertex identical to the vertex of the lens 4
detected before by the first lens sensor 41. Thus, in this case,
the calculated rough-adjustment inclination angle is almost equal
to the actual inclination angle .theta. of the sheet 3. On the
other hand, when the nearest peak of the detection signal of the
second lens sensor 42 is earlier than the peak of the detection
signal of the first lens sensor 41, the nearest peak corresponds to
the vertex one vertex before the vertex of the lens 4 detected by
the first lens sensor 41. Thus, the rough-adjustment inclination
angle calculated in this case differs from the actual inclination
angle .theta., but this presents no problem because the inclination
angle .theta. does not necessarily become 0.degree. in the rough
adjustment.
[0088] After the rough adjustment, the fine adjustment is carried
out. In the fine adjustment, basically as in the case of the
calculation of the rough-adjustment inclination angle, a conveyance
length L2 to the peak of the detection signal of the third lens
sensor 42 nearest to a criterion, which is the peak of the
detection signal of the first lens sensor 41, is calculated. Next,
by substituting the conveyance length L2 for the conveyance length
LA into the above expression (1), a fine-adjustment inclination
angle is obtained.
[0089] The fine-adjustment inclination angle calculated as
described above is equal to the actual inclination angle .theta.
after the rough adjustment. Since the fine adjustment is carried
out after the rough adjustment, the inclination angle .theta. is
sufficiently small. Thus, in the fine adjustment, when the
inclination direction of the sheet 3 is the counterclockwise
direction, the peak of the detection signal of the third lens
sensor 43 is later than the peak of the detection signal of the
first lens sensor 41. When the inclination direction of the sheet 3
is the clockwise direction, on the contrary, the peak of the
detection signal of the third lens sensor 43 is earlier than the
peak of the detection signal of the first lens sensor 41. Thus, it
is possible to judge the inclination direction from the peaks of
the detection signals of the first lens sensor 41 and the third
lens sensor 43.
[0090] The controller 24 turns the clamper 15 based on the judged
inclination direction of the sheet 3 and the calculated
fine-adjustment inclination angle so as to make the inclination
angle .theta. of the sheet 3 into 0.degree.. Note that, when the
fine-adjustment inclination angle is 0.degree., it is unnecessary
to turn the clamper 15 in the fine adjustment.
[0091] In FIG. 9, the clamper shifting mechanism 16 is constituted
of movable plates 51 and 52, a cam 53, clutch discs 54a and 54b, a
motor 55, and the like. On the side of the movable plate 52,
another set of the cam 53, the clutch discs 54a and 54b, the motor
55, and the like is provided in a like manner, though it is not
shown in the drawing.
[0092] The movable plates 51 and 52 are attached to side surfaces
of the platen drum 10 so as to sandwich the platen drum 10, and are
movable in the radial direction. The movable plate 51, 52 is biased
downward by a biasing means, for example, springs 60, and makes
contact with a cam face of the cam 53 disposed under each movable
plate 51, 52. The cam 53 is rotatably attached to each side surface
of the platen drum 10.
[0093] The clutch disc 54b on a motor side is movable between a
disengaged position away from the clutch disc 54a on a cam side as
shown in the drawing and an engaged position engaged therewith. In
the engaged position, the clutch discs 54a and 54b transmit
rotation without a slip. When the rotation position of the platen
drum 10 is set in the standby position, the clutch disc 54b can be
engaged with the clutch disc 54a. The standby position is a
position of waiting for the insertion of the sheet front end
portion of the sheet 3 fed from the feeding path 6 into between the
platen drum 10 and the clamper 15.
[0094] The motors 55 rotate the clutch discs 54b under control of
the controller 24. Thus, the cams 53 are rotated, and the clamper
15 is shifted in the radial direction integrally with the movable
plates 51 and 52. In the cam 53, there are formed cam faces 53a to
53c, which correspond to the retracted position, the first catching
position, and the second catching position of the clamper 15,
respectively. By regulating a rotation angle of the cam 53, one of
the cam faces 53a to 53c comes into contact with the bottom surface
of the movable plate 51, 52. Thereby, the clamper 15 is shifted to
one of the retracted position, the first catching position, and the
second catching position.
[0095] Each of the cam faces 53b and 53c corresponding to the first
and second catching positions is planar, and makes contact with the
bottom surface of the movable plate 51, 52 in a state parallel to a
direction orthogonal to a moving direction of the movable plate 51,
52. The pair of springs 60 has the same biasing force. Thus, even
if the clutch plate 54b is in the disengaged position, the biasing
force of the springs 60 prevents the rotation of the cam 53 pressed
by the movable plate 51, 52, and stably holds the clamper 15 in
first or second catching position.
[0096] Note that, the cam face 53b corresponding to the first
catching position and the cam face 53c corresponding to the second
catching position are joined by a curved surface the diameter of
which is equal to or smaller than a distance between the cam face
53c and the center of the cam 53. Thus, when the clamper 15 is
shifted between the first catching position and the second catching
position, the clamper 15 is not shifted to the side of the
retracted position beyond the second catching position.
[0097] The clamper 15 is provided with a shaft 56 at an end on the
side of the movable plate 52, and two shafts 57 at the other end on
the side of the movable plate 51. The shaft 56 is attached to the
movable plate 52 at one end, and is turnable in a turning direction
centering on the radial direction of the platen drum 10. The
movable plate 51 has a long opening 51a formed parallel to a
tangential direction of the platen drum 10. The shafts 57 extend
through the long opening 51a. Thereby, the clamper 15 is turnable
around a turning axis (hereinafter called clamper turning axis)
orthogonal to the sheet surface of the sheet 3. In this embodiment,
the clamper turning axis passes through an attachment position of
the shaft 56 to the movable plate 52, but may pass through a center
of the clamper 15 in the width direction, for example.
[0098] The clamper turning mechanism 17 is constituted of a
mechanism for holding the clamper 15 in a turnable manner, as
described above, plates 58a and 58b, an actuator 59, and the like.
The slide plate 58a is fixed on ends of the shafts 56 outside the
movable plate 51. The slid plate 58b is shifted between a
disengaged position shown in FIG. 9 and an engaged position for
tightly contacting with the slide plate 58a with appropriate
pressure. When the platen drum 10 is in the standby position, the
slide plate 58b can tightly come into contact with the slide plate
58a.
[0099] The surface of each slide plate 58a, 58b has appropriate
elasticity and a high coefficient of friction. In the engaged
position, the slide plates 58a and 58b slide integrally. Note that,
the slide plate 58b is longer than the slide plate 58a in a
movement direction of the clamper 15. Even if the clamper 15 is in
any of the retracted position, the first catching position, and the
second catching position, the slide plate 58b can make tightly
contact with the slide plate 58a.
[0100] The actuator 59 slides the slide plate 58b being in the
engaged position under control of the controller 24. Thus, the
clamper 15 is turned around the clamper turning axis, to correct
the skew of the sheet 3 caught by the clamper 15. This turning
operation is carried out in a state of setting the clamper 15 in
the second catching position.
[0101] When the clamper 15 is turned, the distance between the
slide plate 58a and the end of the clamper 15 is varied. Thus, each
of the above shafts 57 is extendable and shortenable. Each shaft is
biased by a contained spring, for example, in a direction of
shortening its length. Accordingly, the length of the shaft 57 is
extended and shortened in accordance with variation of the distance
between the slide plate 58a and the end of the clamper 15. Note
that, the shaft 56 may be extended or shortened. Alternatively, a
surface of the movable plate 51 and a surface of the slide plate
58a that make contact with each other may be formed into curved
surfaces, so that the distance between the slide plate 58a and the
end of the clamper 15 is not varied.
[0102] Note that, when the slide plates 58a and 58b are set in the
disengaged position, the clamper 15 is not turned around the
clamper turning axis due to the friction between the slide plate
58a and the movable plate 51 and the like. A brake mechanism or the
like may be separately provided in order to prevent an
unintentional movement or turn of the clamper 15.
[0103] As shown in FIG. 1, the rear end clamps 27 are disposed at
appropriate distance away from clamper 15 in the circumferential
direction of the platen drum 10. The rear end clamps 27 are
provided on both of the side surfaces of the platen drum 10, and
catch both side edges of the rear end portion of the sheet 3
between themselves and the outer circumferential surface 10b.
[0104] As shown in FIG. 10, the rear end clamp 27 is movable
between a catching position in which one end 27a catches the side
edge of the sheet 3 between itself and the platen drum 10 and a
release position in which the end 27a opens outward from the
catching position as shown in a chain double-dashed line to release
the catch of the sheet 3.
[0105] The open/close mechanism 28 for operating the rear end clamp
27 is constituted of a cam 61, clutch discs 62a and 62b, a motor
63, and the like. The other end 27b of the rear end clamp 27 is
biased so as to make contact with a cam face of the cam 61, and a
sliding position onto the cam face is changed by the rotation of
the cam 61, so the rear end clamp 27 is movable between the
catching position and the release position.
[0106] The clutch disc 62b on a motor side is disposed in a
position slightly advanced from the peeling claw 19 in the rotation
direction of the platen drum 10 in printing, in other words, in the
forward direction. To operate the rear end clamps 27, the platen
drum 10 is rotated to a rotation position (hereinafter called rear
end clamp open/close position) in which the clutch disc 62a is
faced to the clutch disc 62b. The clutch disc 62b is moved between
a disengaged position away from the clutch disc 62b as shown in the
drawing and an engaged position engaged therewith. The motor 63,
which is controlled by the controller 24, rotates the cam 53
through the clutch disc 62b set in the engaged position. Thus, the
rear end clamps 27 are set at one of the catching position and the
release position.
[0107] Next, referring to a flowchart shown in FIG. 11, printing on
the lenticular sheet will be described. First, data of the two
viewpoint images, in which the same scene is viewed from different
viewpoints, is inputted to an input I/F (not shown) of the printer
2. These two viewpoint images are temporarily stored on a memory
(not shown) of the controller 24 as the parallax image. A data
conversion section provided in the controller 24 reads out the two
viewpoint images from the memory, and converts the two viewpoint
images into data of six viewpoint images. The data of the six
viewpoint images is stored on the memory again.
[0108] When the start of printing is directed, the controller 24
confirms that the platen drum 10 is in the standby position and the
slide plate 58b of the clamper turning mechanism 17 is in the
disengaged position. Next, the controller 24 engages the clutch
disc 54b with the clutch disc 54a, and then shifts the clamper 15
to the retracted position by controlling the clamper shifting
mechanism 16. Note that, the position of the clamper 15 may be
detected by a position sensor or the like, and the clamper shifting
mechanism 16 may be controlled based on a detection result. When
the clamper 15 is shifted to the retracted position, the rotation
position of the clamper 15 may be detected by a rotary encoder or
the like, and the clamper turning mechanism 17 maybe controlled
based on a detection result so as to parallel the clamper 15 with
the main scan direction.
[0109] After the clamper 15 is set in the retracted position, the
single sheet 3 is fed from the paper feed cassette 9 into the
feeding path 6. After that, the sheet 3 is conveyed downward while
being nipped by the feeding roller pair 7 rotated by the motor 12.
Through this conveyance, the sheet 3 is sent through the sensor
section 8 to the platen drum 10. The feeding roller pair 7 conveys
the sheet 3 by a certain length from the time when the sensor
section 8 detects the front end of the sheet 3. Then, after the
sheet front end portion is made ready to be caught by the clamper
15, the rotation of the motor 12 is stopped to halt the conveyance
of the sheet 3.
[0110] After the conveyance of the sheet 3 is stopped, the
controller 24 actuates the clamper shifting mechanism 16 to set the
clamper 15 in the first catching position. Thus, the sheet front
end portion is caught between the clamper 15 and the outer
circumferential surface 10b of the platen drum 10. At this time,
the entire pressing surface 32a of the pressing member 32 is
tightly in contact with the sheet front end portion, because the
clamper 15 is in the first catching position.
[0111] After the clamper 15 catches the sheet front end portion,
the feeding roller pair 7 releases the nip of the sheet 3, and the
clutch disc 54b of the clamper shifting mechanism 16 is moved to
the disengaged position. Furthermore, after the thermal head 18 is
confirmed to be set in the retracted position, the controller 24
actuates the motor 14. Thereby, the platen drum 10 rotates in the
forward direction, and the sheet 3 starts being conveyed in the sub
scan direction.
[0112] During this conveyance, the controller 24 carries out the
judgment of the inclination direction and the calculation of the
rough-adjustment inclination angle, based on the detection signals
from the lens sensors 41 to 43. As described above, the inclination
direction of the lens 4 is judged based on the detection signals
from the lens sensors 41 to 43, and the rough-adjustment
inclination angle is calculated based on the detection signals of
the first and second lens sensors 41 and 42 after the judgment of
the inclination direction.
[0113] When the judgment of the inclination direction and the
calculation of the rough-adjustment inclination angle are
completed, the rotation direction of the motor 14 is switched, so
the platen drum 10 is reversely rotated and returned to the standby
position. At this time, the sheet 3 is conveyed upstream of the
feeding path 6.
[0114] When the platen drum 10 is stopped in the standby position,
the clutch disc 54b is engaged with the clutch disc 54a. After
that, the clamper shifting mechanism 16 shifts the clamper 15 from
the first catching position to the second catching position. At
this shift, clamper 15 is directly shifted from the first catching
position to the second catching position with preventing the
clamper 15 from being set in the retracted position by controlling
the rotation direction of the cam 53. Accordingly, the pressing
surface 32a moves away from the sheet 3, and only the projections
32b press the sheet front end portion.
[0115] Subsequently, the slide plate 58b is moved to the engaged
position to be engaged with the slide plate 58a, and then the
clamper turning mechanism 17 turns the clamper 15. At this time,
the operation of the actuator 59 is controlled such that the
clamper 15 is turned in a direction opposite to the judged
inclination direction by the same angle as the rough-adjustment
inclination angle.
[0116] When the clamper 15 is turned as described above, the sheet
3 is turned together with the clamper 15, and the position of the
sheet 3 is changed to roughly adjust the inclination of the lenses
4 in the longitudinal direction relative to the main scan
direction. At this time, since the clamper 15 is set in the second
catching direction, the sheet front end portion does not slip off
from the projections 32b, but easily slips off from the front
surface of the drum body 34. Therefore, the sheet 3 is rotated only
by the rough-adjustment inclination angle with precision.
[0117] After the completion of the rough adjustment, the slide
plate 58a is set in the disengaged position, and the clamper
shifting mechanism 16 shifts the clamper 15 from the second
catching position to the first catching position. At this shift,
the clamper 15 is directly shifted from the second catching
position to the first catching position without being set in the
retracted position.
[0118] After the clutch disc 54b is set in the disengaged position,
the platen drum 10 is rotated in the forward direction, and the
sheet 3 starts to be rotated in the sub scan direction. During the
conveyance of the sheet 3, the fine-adjustment inclination angle is
calculated based on the detection signals from the first and third
lens sensors 41 and 43.
[0119] After the calculation of the fine-adjustment inclination
angle, the rotation direction of the motor 14 is switched, and the
platen drum 10 is reversely rotated and returned to the standby
position. When the platen drum 10 is stopped in the standby
position, as in the case of the rough adjustment, the clamper
shifting mechanism 17 shifts the clamper 15 from the first catching
position to the second catching position. After that, the slide
plate 58b is returned to the engaged position, and then the clamper
turning mechanism 17 turns the clamper 15 based on a judgment
result of the inclination direction and a calculation result of the
fine-adjustment inclination angle, so as to parallel the
longitudinal direction of the lenses 4 with the main scan direction
in the fine adjustment.
[0120] After the completion of the fine adjustment, the slide plate
58b is shifted to the disengaged position, and the clamper shifting
mechanism 16 shifts the clamper 15 to the first catching position.
After that, the clutch disc 54b is set in the disengaged
position.
[0121] After the skew of the sheet 3 is corrected as described
above, the sheet 3 is wound onto the platen drum 10. To wind the
sheet 3 onto the platen drum 10, the platen drum 10 is rotated
forward. By this rotation, the sheet 3 is pulled out of the feeding
path 6, and successively wound onto the outer circumferential
surface 10b. During the conveyance of the sheet 3, a lens pitch of
the sheet 3 is checked based on a detection result of the sensor
section 8. Note that, the lens pitch can be calculated as the
conveyance length from the time when the detection signal of the
sensor section 8 reaches its peak to the time when the detection
signal reaches the next peak, for example.
[0122] When even the rear end of the sheet 3 is wound onto the
platen drum 10, the rotation of the platen drum 10 is continued
until the platen drum 10 arrives at the rear end clamp open/close
position. When the platen drum 10 is stopped in the rear end clamp
open/close position, the clutch disc 62b is engaged with the clutch
disc 62a, and the open/close mechanism 28 sets the rear end clamp
27 in the catching position. Thus, the sheet front end portion is
clamped by the rear end clamps 27.
[0123] The clutch disc 62b is set in the disengaged position, and
the platen drum 10 is rotated forward. When the clamper 15 is moved
to a position beyond the thermal head 18, the platen drum 10 is
stopped. After the image receptor film of the print film 21 is set
directly under the thermal head 18, the thermal head 18 is shifted
to the pressing position. Thus, the thermal head 18 presses the
image receptor film against the back surface of the sheet 3.
[0124] After the press of the thermal head 18, the platen drum 10
is forward rotated again. Thus, the sheet 3 starts to be conveyed
in the sub scan direction. The image receptor film is fed in
synchronization with the conveyance of the sheet 3. After the start
of the conveyance of the sheet 3, the controller 24 monitors the
conveyance length of the sheet 3 based on the number of drive
pulses supplied to the motor 14. When it is detected that the print
area of the sheet 3 arrives at the thermal head 18 by monitoring
the conveyance length, the head driver 22 is directed to form the
image receptor layer.
[0125] The head driver 22 supplies the two heating element arrays
18a of the thermal head 18 with common electric power to generate
heat therein, and heats the image receptor film. Thus, the image
receptor film is evenly heated, and the two lines of the
transparent image receptor layer extending long in the main scan
direction are transferred side by side to the small area 5a, for
example.
[0126] After the two lines of the image receptor layer are formed
in the small area 5a, the sheet 3 is conveyed only by a conveyance
length corresponding to one-sixth of the lens pitch detected
before. This intermittent conveyance amount corresponds to a print
width of the single stripe image, and is equal to the width of the
small area. Concurrently with this, the image receptor film is
shifted by two lines. After the shift, the thermal head 18 is
actuated again to heat the image receptor film. Thereby, the image
receptor layer is formed in the small area 5b adjoining to the
small area 5a in which the image receptor layer is formed
earlier.
[0127] Likewise, with the conveyance of the sheet 3 and the image
receptor film, the image receptor layer is formed on a two-line
basis, and the transparent image receptor layer is formed in the
entire print area in the end.
[0128] After the formation of the image receptor layer is
completed, the thermal head 18 is returned to the retracted
position. The platen drum 10 continues to be rotated forward, and
is stopped when the clamper 15 is moved to the position beyond the
thermal head 18. After that, the yellow ink film of the print film
21 is set directly under the thermal head 18, and the thermal head
18 is shifted to the pressing position. Thereby, the yellow ink
film is overlaid on the back surface of the sheet 3.
[0129] After the press of the thermal head 18, the platen drum 10
is rotated forward to convey the sheet 3 again. At this time, the
controller 24 monitors the conveyance length of the sheet 3, and
when the heating element arrays 18a of the thermal head 18 are
positioned in the first small area 5a of the print area, two
adjoining lines of an yellow image of, for example, the first
viewpoint image out of the six viewpoint images is read out. The
thermal head 18 is driven based on data of the yellow image. By the
heat generation of the two heating element arrays 18a, the yellow
ink film is heated from behind. Thus, yellow ink sublimed from the
yellow ink film adheres to the image receptor layer of the small
area 5a. As a result, the single stripe image consisting of the two
lines of the yellow image is printed on the small area 5a.
[0130] After the print on the small area 5a, the sheet 3 is
conveyed by the rotation of the platen drum 10 only by the
conveyance length corresponding to one-sixth of the lens pitch.
Concurrently with the conveyance of the sheet 3, the yellow ink
film is wound up such that an unused portion thereof is faced to
the thermal head 18 instead of a used portion. After the
conveyance, two adjoining lines of yellow image data of the second
viewpoint image are read out, and the head driver 22 makes the two
heating element arrays 18a generate heat in accordance with the
yellow image data, so the stripe image consisting of the two lines
of the yellow image is printed on the small area 5b.
[0131] Likewise, whenever the sheet 3 and the yellow ink film are
conveyed by the conveyance length corresponding to one-sixth of the
lens pitch, the thermal head 18 is actuated based on the two lines
of the yellow image data, to print the stripe images of the first
to sixth viewpoint images on the small areas 5a to 5f,
respectively.
[0132] When the yellow images are completely printed on the entire
print area of the sheet 3, the thermal head 18 is shifted to the
retracted position. The platen drum 10 continues to be rotated
forward, and is stopped in a position where the clamper 15 passes
by the thermal head 18. Then, the print film 21 is fed so as to set
the magenta ink film directly under the thermal head 18. After
that, the thermal head 18 is shifted to the pressing position.
[0133] As in the case of the yellow images described above, while
the sheet 3 and the magenta ink film are conveyed intermittently,
each magenta image of the first to sixth viewpoint images is split
into stripe images, and the stripe images are printed on the back
surface of the sheet 3 so as to be overlaid on the stripe images of
the yellow images. After a single screen of the magenta images is
completely printed, cyan images are printed on the sheet 3 using
the cyan ink film.
[0134] After the cyan images are printed, the thermal head 18 is
shifted to the retracted position. The platen drum 10 continues to
be rotated to a position where the clamper 15 passes by the thermal
head 18, and is stopped. After that, the back layer film of the
print film 21 is set directly under the thermal head 18, and then
the thermal head 18 is shifted to the pressing position. While the
sheet 3 is intermittently conveyed again by the forward rotation of
the platen drum 10, the thermal head 18 is actuated to form the
back layer on the print area on which the images of three colors
have already been printed.
[0135] After the formation of the back layer, the thermal head 18
is shifted to the retracted position. The platen drum 10 is forward
rotated a little, and stopped in the rear end clamp open/close
position. After the platen drum 10 is stopped, the clutch disc 62b
is shifted to the engaged position, and then the rear end clamps 27
are moved to the release position by the open/close mechanisms 28.
The peeling claw 19 is swung to the peeling position in which the
peeling claw 19 is in contact with the outer circumferential
surface 10b.
[0136] After that, the platen drum 10 is rotated reversely. When
the rear end of the sheet 3 arrives at the position of the peeling
claw 19 by this reverse rotation, the peeling claw 19 scoops up the
rear end of the sheet 3 from the outer circumferential surface 10b.
The platen drum 10 continues to be rotated reversely, so the sheet
3 is guided to the cutter unit 25 from its rear end.
[0137] When the platen drum 10 arrives at the standby position by
the reverse rotation, the reverse rotation of the platen drum 10 is
temporarily stopped. At this time, the sheet 3 fed into the cutter
unit 25 has reached a constant length, and the conveyance mechanism
of the cutter unit 25 can convey the sheet 3.
[0138] When the platen drum 10 is stopped in the standby position,
as described above, the clamper shifting mechanism 16 shifts the
clamper 15 to the retracted position. After that, since the
conveyance mechanism of the cutter unit 25 conveys the sheet 3, the
front end of the sheet 3 is pulled out from between the clamper 15
and the platen drum 10, and the entire sheet 3 is conveyed to the
cutter unit 25. In the cutter unit 25, the sheet front end portion
and the sheet rear end portion being margins in which no image is
printed are cut off, and the remaining sheet 3 is ejected. In the
case of carrying out printing on another sheet 3, the above
procedure is repeated.
[0139] In the above embodiment, the non-formation area in which no
elastic layer is formed has a rectangular shape with appropriate
widths in the main scan direction and the sub scan direction, but
may be in another shape as long as the non-formation area is formed
in the outer circumferential surface of the platen drum at least at
areas facing to the projections and shiftable areas of the
projections by the turning mechanism. In an embodiment shown in
FIG. 12, non-formation areas 36a and 36b are formed only in
portions at which projections 32b tightly make contact with the
sheet 3 plus surroundings of the portions. In correcting the skew
of the sheet 3, since the clamper 15 is turned and the projections
32b are shifted, the non-formation areas 36a and 36b are formed in
the shiftable areas of the projections 32b. Note that, in this
embodiment of FIG. 12, the non-formation area 36b on the side of
the shaft 56 is small, while the non-formation area 36a on the side
of the shaft 57 is large, considering the fact that the clamper
pivots on the shaft 56.
[0140] The projections provided in the pressing member 32 may be
different in size from each other. In an embodiment shown in FIG.
13, a projection 71 on a pivot side of the clamper 15 that is moved
a little relative to the other is made small, while a projection 72
on the opposite of the pivot side that is moved much is made large
to increase the size of a contact area with the sheet 3. Note that,
the number of the projections provided in the pressing member of
the clamper 15 may be three or more.
[0141] In each of the above embodiments, the printer of a platen
drum type having the platen drum as the support member is
described, but a flat platen table that moves integrally with the
clamper or the like may be used, instead of the platen drum. In
another case, the fixed platen table or a platen roller with a
small diameter may be disposed in a position facing to the thermal
head. The thermal head may be pressed against the sheet on the
platen table or the platen roller for printing, while the sheet may
be caught between the clamper and the support member provided
separately from the platen table, and the support member and the
clamper may be integrally moved in the sub scan direction to convey
the sheet.
[0142] In each of the above embodiments, the line printer is
described, but the present invention is applicable to a printer of
another type, such as a serial printer. Furthermore, the present
invention is applicable not only to the printing of the parallax
image for recording the 3D image, but also to the printing of
so-called changing, in which a viewable image is changed with a
change of an observation position. The present invention is usable
in a thermal fusion type of thermal printer, an inkjet printer, and
the like, in addition to a sublimation type.
[0143] Furthermore, the printer is described above, but the
clamping device according to the present invention is also
applicable to various types of equipment that require switching
between a skew correction state and a sheet fixing state, other
than the printer. For example, the present invention is applicable
to a cutting device that cuts the lenticular sheet into appropriate
size in such a manner that its cutting direction is orthogonal or
parallel to the longitudinal direction of the lenses. In this
cutting device, the lenticular sheet on the support member is
pressed and caught by the clamper. To correct the skew of the
lenticular sheet relative to a cutting blade, the clamper is set in
the second catching position and turned. When cutting the
lenticular sheet, the clamper is set in the first catching position
to prevent a slip of the lenticular sheet. The present invention is
usable to the case of not conveying the sheet, as a matter of
course.
[0144] The clamping device catches the lenticular sheet at any
portion as long as it does not interfere with a process to be
carried out while catching the lenticular sheet, such as printing
of an image, cutting, and the like. In the printer, the lenticular
sheet can be caught at any portion on which no image is printed,
and the portion preferably could be a sheet end portion including
the sheet front end portion, the sheet rear end portion, side end
portions, and the like. In the case of cutting out the lenticular
sheet into constant size, the lenticular sheet can be caught at its
middle portion.
DESCRIPTION OF THE REFERENCE NUMERALS
[0145] 2 printer
[0146] 3 lenticular sheet
[0147] 4 lens
[0148] 8 sensor section
[0149] 10 platen drum
[0150] 15 clamper
[0151] 16 clamper shifting mechanism
[0152] 17 clamper turning mechanism
[0153] 18 thermal head
[0154] 24 controller
[0155] 32 pressing member
[0156] 32a pressing surface
[0157] 32b projection
* * * * *