U.S. patent application number 09/833608 was filed with the patent office on 2001-08-09 for pressure-sensitive and heat-sensitive image transfer apparatus for recording.
This patent application is currently assigned to ASAHI KOGAKU KOGYO KABUSHIKI KAISHA. Invention is credited to Furusawa, Koichi, Orita, Hiroshi, Saito, Hiroyuki, Suzuki, Katsuyoshi, Suzuki, Minoru.
Application Number | 20010012103 09/833608 |
Document ID | / |
Family ID | 12023963 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010012103 |
Kind Code |
A1 |
Suzuki, Minoru ; et
al. |
August 9, 2001 |
Pressure-sensitive and heat-sensitive image transfer apparatus for
recording
Abstract
An image transfer apparatus that records an image through
selective heat and pressure application has an ink ribbon and a
film disposed between a driving head and a flat platen. Color dyes
of the ink ribbon are transferred to the film as the image. The
image on the film is thus conveyed to a position for transferring
the image to a recording sheet. The film and the recording sheet
are pressed between a transfer roller and a conveyor roller with a
pressure that sufficiently smooths unevenness in the surface of the
recording sheet. A high quality image is thus recorded on the
recording sheet regardless of the surface condition of the
recording sheet.
Inventors: |
Suzuki, Minoru; (Tochigi,
JP) ; Orita, Hiroshi; (Saitama, JP) ; Saito,
Hiroyuki; (Saitama, JP) ; Suzuki, Katsuyoshi;
(Tokyo, JP) ; Furusawa, Koichi; (Tokyo,
JP) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN
1941 ROLAND CLARKE PLACE
RESTON
VA
20191
|
Assignee: |
ASAHI KOGAKU KOGYO KABUSHIKI
KAISHA
Tokyo
JP
|
Family ID: |
12023963 |
Appl. No.: |
09/833608 |
Filed: |
April 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09833608 |
Apr 13, 2001 |
|
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09231801 |
Jan 15, 1999 |
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6246465 |
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Current U.S.
Class: |
355/400 ; 355/35;
355/40; 355/405; 430/138 |
Current CPC
Class: |
B41M 5/287 20130101;
B41J 2/32 20130101 |
Class at
Publication: |
355/400 ;
355/405; 355/35; 355/40; 430/138 |
International
Class: |
G03B 027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 1998 |
JP |
P10-020324 |
Claims
What is claimed is:
1. An image transfer apparatus that records an image through
selective heat and pressure application, comprising: a conveyor
unit that moves a recording sheet in a transport direction; an
ink-transfer ribbon that comprises a base member and a layer of
micro-capsules, coated over said base member, that contains a
plurality of micro-capsules filled with dye, said plurality of
micro-capsules exhibiting a temperature/pressure characteristic
such that, when said each micro-capsule is squashed under a
corresponding predetermined pressure at a corresponding
predetermined temperature; a thermal head unit, performing a
printing operation on said base member, that includes a temperature
application unit selectively and locally heating said layer of
micro-capsules to predetermined temperatures and a pressure
application system locally applying predetermined pressures to said
layer of micro-capsules, said predetermined temperatures including
said corresponding predetermined temperature and said predetermined
pressures including said corresponding predetermined pressure; and
a rotating member having a smooth outer surface that resiliently
contacts said layer of micro-capsules and said recording surface of
said recording sheet, said rotating member moving in
synchronization with said movement of said recording sheet such
that said transfer of said image to said recording surface of said
recording sheet occurs, said rotating member configured to apply a
pressure greater than said corresponding predetermined pressure to
said recording sheet.
2. The image transfer apparatus of claim 1, wherein said conveyor
unit intermittently moves said recording sheet, and said thermal
head performs a line by line printing operation on said base member
in a recording direction substantially perpendicular to said
transport direction.
3. The image transfer apparatus of claim 1, wherein said thermal
head and said ink-transfer ribbon extend in parallel across
substantially a width of said recording sheet.
4. The image transfer apparatus of claim 1, wherein said plurality
of micro-capsules filled with dye comprises at least three types of
micro-capsules having a different shell wall breaking under said
corresponding predetermined pressure at said corresponding
predetermined temperature and a corresponding different color
dye.
5. The image transfer apparatus of claim 1, wherein said thermal
head is tangentially aligned with said rotating member such that
said predetermined pressures are applied by said pressure
application system due to said alignment.
6. An image transfer apparatus for recording an image through
selective heat and pressure application, comprising: a conveyor
unit that moves a recording sheet in a transport direction; an
ink-transfer ribbon that comprises a base member and a layer of
micro-capsules, coated over said base member, that contains a
plurality of micro-capsules filled with dye, said plurality of
micro-capsules exhibiting a temperature/pressure characteristic
such that, when each of said plurality of micro-capsules is
squashed under a corresponding predetermined pressure at a
corresponding predetermined temperature, said dye discharges from
said squashed micro-capsule and transfers as said image to a
recording surface of said recording sheet; a thermal head unit,
performing a printing operation on said base member, that includes
a temperature application unit selectively and locally heating said
layer of micro-capsules to predetermined temperatures and a
pressure application system locally applying predetermined
pressures to said layer of micro-capsules, said predetermined
temperatures including said corresponding predetermined temperature
and said predetermined pressures including said corresponding
predetermined pressure; a first rotating member having a releasant
coated outer surface that resiliently contacts said ink-transfer
ribbon as a part of said pressure application system; and a second
rotating member that resiliently contacts said layer of
micro-capsules to said recording surface of said recording sheet,
said second rotating member moving in synchronization with said
movement of said recording sheet such that said transfer of said
image to said recording surface of said recording sheet occurs,
said second rotating member configured to apply a pressure, which
is within a predetermined range, to said recording sheet.
7. The image transfer apparatus of claim 6, wherein said conveyor
unit intermittently moves said recording sheet, and said thermal
head performs a line by line printing operation on said base member
in a recording direction substantially perpendicular to said
transport direction.
8. The image transfer apparatus of claim 6, wherein said thermal
head and said ink-transfer ribbon extend in parallel across
substantially a width of said recording sheet.
9. The image transfer apparatus of claim 6, wherein said plurality
of micro-capsules filled with dye comprises at least three types of
micro-capsules having a different shell wall breaking under said
corresponding predetermined pressure at said corresponding
predetermined temperature and a corresponding different color
dye.
10. The image transfer apparatus of claim 6, wherein said thermal
head is tangentially aligned with said first rotating member such
that said predetermined pressures are applied by said pressure
application system due to said alignment.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image transfer apparatus
used in a high-resolution printer for pressure-sensitive and
heat-sensitive recording of an image on a recording sheet, and more
particularly for recording an image by locally pressing and
selectively heating a recording material that includes capsule.
[0003] 2. Description of the Related Art
[0004] An ink is known that includes fine capsules, such as
micro-capsules, filled with heat-sensitive color developing dye or
ink for high-resolution printing in a high resolution color
printer. A recording sheet consists of a base sheet with a layer of
the micro-capsules covering the base sheet. The layer of
micro-capsules includes a plurality of types of micro-capsule, each
type corresponding to a specific color ink or dye, which seeps from
the micro-capsule onto the recording sheet when the corresponding
micro-capsule is heated to a predetermined temperature. The
predetermined temperature varies dependent on the type of
micro-capsule. Each seeped color ink or dye is developed and fixed
by light of a predetermined wavelength, which also varies dependent
on the type of micro-capsule. Therefore, each type of micro-capsule
seeps a predetermined color ink or dye when heated to the
predetermined temperature, and the seeped color is developed and
fixed on the base sheet by irradiation with the light of the
specific wavelength. Thus, ink or dye discharge to generate a
full-color image, to be recorded on a recording sheet, can be
controlled through selection of the micro-capsules to seep the dye
or ink, which occurs through control of a localized heating and
irradiation with a specific wavelength of light.
[0005] The recording process utilizing the recording sheet with the
layer of the micro-capsules is complicated and time-consuming,
because the localized heating and light irradiation must be
repeatedly executed in order to develop and fix a plurality of
colors. When the base sheet is a normal sheet of plain paper, it
becomes difficult to record a high-resolution image on the base
sheet, because the normal paper usually has an uneven printing
surface.
SUMMARY OF THE INVENTION
[0006] Therefore, an object of the present invention is to provide
a pressure-sensitive and heat-sensitive image transfer apparatus
for easily recording a full-color high-resolution image on a
recording sheet through control of localized pressure and
temperature, regardless of a surface condition of the recording
sheet.
[0007] An image transfer apparatus according to the present
invention comprises an image generating unit that includes an image
carrying member and a layer of micro-capsules containing dye, each
micro-capsule disposed in the layer of micro-capsules exhibits a
temperature/pressure characteristic such that, when the each
micro-capsule is squashed under a corresponding predetermined
pressure at a corresponding predetermined temperature, the dye
seeps from the squashed micro-capsule and transfers to a surface of
the image carrying member. An image transfer unit is also included
that transfers the transferred dye as the image to a recording
surface of a recording sheet.
[0008] Preferably a shell wall of the each micro-capsule is
composed of a shape memory resin which exhibits a glass-transition
temperature corresponding to the corresponding predetermined
temperature, and a thickness of the shell wall corresponding to the
corresponding predetermined pressure. Further the image transfer
apparatus may include a pressing unit that presses the recording
surface of the recording sheet such that the recording surface is
smoothed to improve a quality of said transferred image. Also the
image transfer apparatus may include a pressure application system
that locally applies a predetermined pressure to the micro-capsule
layer. At least one of the predetermined pressures is the
corresponding predetermined pressure. A heat application system may
be also included that selectively and locally heats the
micro-capsule layer to predetermined temperatures. At least one of
the predetermined temperatures is the corresponding predetermined
temperature. The image transfer apparatus may include a capsule
holding member holding the layer of micro-capsules and a recording
sheet transport unit moving the recording sheet in a transport
direction.
[0009] Preferably the image generating unit selectively and locally
squashes and breaks the micro-capsules between the image carrying
member and the capsule holding member in accordance with a control
of the heat application system and the pressure application system.
Further, the image carrying member may include a continuous belt,
and the image generating unit may include a rotational drive system
rotationally driving the continuous belt. Furthermore, the image
generating unit includes a support member that supports the capsule
holding member, and the image carrying member during the
application of the predetermined pressures and temperatures. The
image transfer unit may include a roller rotating in
synchronization with a movement of the continuous belt. The roller
may press the recording sheet to resiliently contact the image
carrying member such that the transferred dye is accurately
transferred to the recording sheet as the image.
[0010] Preferably, the image carrying member includes a platen
roller, and the image transfer unit includes a rotational drive
system rotationally driving the platen roller in synchronization
with the movement of the recording sheet and a second roller. The
second roller may presses the recording sheet to resiliently
contact the image carrying member, such that the transferred dye is
accurately transferred as the image to the recording sheet.
Preferably, the capsule holding member disposed on the image
carrying member and the image generating unit further includes an
adhesion preventing member coated with a releasant that prevents
adhesion of the transferred dye. Also preferably, the image
generating unit selectively and locally squashes and breaks the
micro-capsules between the image carrying member and the adhesive
preventing member in accordance with a control of the heat
application system and the pressure application system. Further,
the image carrying member may include a transport drive system that
drives the image carrying member so that the transferred dye is
transferred as the image to the recording surface of the recording
sheet. The image carrying member may be in resilient contact with
the adhesion preventing member such that the adhesion preventing
member rotates in synchronization with the image carrying member.
Furthermore, the image transfer unit includes a rotating member
that rotates in synchronization with the image carrying member. The
rotating member may press the recording sheet to resiliently
contact the recording surface with the capsule holding member such
that the transferred dye is accurately transferred as the image to
the recording surface.
[0011] An image transfer apparatus according to the present
invention comprises a conveyor unit that intermittently moves a
recording sheet in a transport direction, an ink-transfer ribbon
that comprises a base member and a layer of micro-capsules, coated
over the base member. The layer of micro-capsules contains a
plurality of micro-capsules filled with dye, a shell wall of each
micro-capsule of the plurality of micro-capsules being composed of
resin that exhibits a temperature/pressure characteristic such
that, when the each micro-capsule is squashed under a corresponding
predetermined pressure at a corresponding predetermined
temperature, the dye discharges from the squashed micro-capsule and
transfers as the image to a recording surface of the recording
sheet. A thermal head unit, performing a line by line printing
operation on the base member in a recording direction substantially
perpendicular to the transport direction, is included that includes
a temperature application the selectively and locally heating the
layer of micro-capsules to predetermined temperatures and a
pressure application unit locally applying predetermined pressures
to the layer of micro-capsules. The predetermined temperatures
include the corresponding predetermined temperature and the
predetermined pressures include the corresponding predetermined
pressure. A continuous belt having a smooth outer surface is also
included that resiliently contacts the layer of micro-capsules and
the recording surface of the recording sheet. The continuous belt
moves in synchronization with the movement of the recording sheet
such that the transfer of the image to the recording surface of the
recording sheet occurs.
[0012] Preferably, the plurality of micro-capsules filled with dye
includes at least three types of micro-capsules that have a
different shell wall breaking under the corresponding predetermined
pressure at the corresponding predetermined temperature and a
corresponding different color dye.
[0013] An image transfer apparatus according to the present
invention comprises a conveyor unit that moves a recording sheet in
a transport direction, an ink-transfer ribbon that comprises a base
member and a layer of micro-capsules, coated over the base member.
The layer of micro-capsules contains a plurality of micro-capsules
filled with dye, a shell wall of each of the plurality of
micro-capsules being composed of a resin that exhibits a
temperature/pressure characteristic such that, when the each
micro-capsule is squashed under a corresponding predetermined
pressure at corresponding predetermined temperature, the dye
discharges from the squashed micro-capsule and transfers as the
image to a recording surface of the recording sheet. A thermal head
unit, performing a printing operation on the base member, is
included that includes a temperature application unit selectively
and locally heating the layer of micro-capsules to predetermined
temperatures and a pressure application system locally applying
predetermined pressures to the layer of micro-capsules. The
predetermined temperatures include the corresponding predetermined
temperature and the predetermined pressures include the
corresponding predetermined pressure. A rotating member having a
smooth outer surface is also included that resiliently contacts the
layer of micro-capsules and the recording surface of the recording
sheet. The rotating member moves in synchronization with the
movement of the recording sheet such that the transfer of the image
to the recording surface of the recording sheet occurs.
[0014] Preferably, the conveyor unit intermittently moves the
recording sheet, and the thermal head performs a line by line
printing operation on the base member in a recording direction
substantially perpendicular to the transport direction. The thermal
head and the ink-transfer ribbon may extend in parallel across
substantially a width of the recording sheet. The plurality of
micro-capsules filled with dye may include at least three types of
micro-capsules that have a different shell wall breaking under the
corresponding predetermined pressure at the corresponding
predetermined temperature and a corresponding different color dye.
The thermal head may be tangentially aligned with the rotating
member such that the predetermined pressures are applied by the
pressure application system due to the alignment.
[0015] An image transfer apparatus according to the present
invention comprises a conveyor unit that moves a recording sheet in
a transport direction, an ink-transfer ribbon that comprises a base
member and a layer of micro-capsules, coated over the base member.
The layer of the micro-capsules contains a plurality of
micro-capsules filled with dye, a shell wall of each micro-capsule
of said plurality of micro-capsules being composed of a resin that
exhibits a temperature/pressure characteristic such that, when each
of the plurality of micro-capsules is squashed under a
corresponding predetermined pressure at a corresponding
predetermined temperature, the dye discharges from the squashed
micro-capsule and transfers as the image to a recording surface of
the recording sheet. A thermal head unit, performing a printing
operation on the base member, is included that includes a
temperature application unit selectively and locally heating the
layer of micro-capsules to predetermined temperatures and a
pressure application system locally applying predetermined
pressures to the layer of micro-capsules. The predetermined
temperatures include the corresponding predetermined temperature
and the predetermined pressures include the corresponding
predetermined pressure. A first rotating member, having a releasant
coated outer surface, is also included that resiliently contacts
the ink-transfer ribbon as a part of the pressure application
system. A second rotating member is also included that resiliently
contacts the layer of micro-capsules to the recording surface of
the recording sheet. The second rotating member moves in
synchronization with the movement of the recording sheet such that
the transfer of the image to the recording surface of the recording
sheet occurs.
[0016] Preferably, the conveyor unit intermittently moves the
recording sheet, and the thermal head performs a line by line
printing operation on the base member in a recording direction
substantially perpendicular to the transport direction. The thermal
head and the ink-transfer ribbon may extend in parallel across
substantially a width of the recording sheet. And the plurality of
micro-capsules filled with dye may include at least three types of
micro-capsules that have a different shell wall breaking under the
corresponding predetermined pressure at the corresponding
predetermined temperature and a corresponding different color dye.
The thermal head may be tangentially aligned with the first
rotating member such that the predetermined pressures are applied
by the pressure application system due to the alignment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will be better understood from the
description of the preferred embodiments of the invention set forth
below together with the accompanied drawings, in which:
[0018] FIG. 1 is a cross-sectioned elevational view showing a
high-resolution color printer of a first embodiment for
pressure-sensitive and heat-sensitive recording;
[0019] FIG. 2 is a perspective view showing a transfer apparatus
used in the color printer;
[0020] FIG. 3 is a cross-sectioned elevational view showing a
structure of an ink ribbon of the color printer;
[0021] FIG. 4 is a cross-sectional view showing different types of
micro-capsule utilized in the first embodiment;
[0022] FIG. 5 is a diagram showing a characteristic relationship
between temperature and elasticity coefficient of a shape memory
resin of the micro-capsules;
[0023] FIG. 6 is a diagram showing a characteristic relationship
between temperature and breaking pressure of a capsule wall of the
micro-capsules;
[0024] FIG. 7 is a perspective view showing a transfer apparatus of
a second embodiment used in the color printer;
[0025] FIG. 8 is an elevational view showing a roller platen and a
thermal head of the second embodiment;
[0026] FIG. 9 is a perspective view showing a modified driving head
and the roller platen of a the second embodiment used in a serial
printer;
[0027] FIG. 10 is a perspective view showing a transfer apparatus
of a third embodiment used in the color printer;
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] Hereinafter, the preferred embodiments of the present
invention are described with reference to the attached
drawings.
[0029] FIG. 1 is a cross-sectioned elevational view of a
high-resolution color printer 10 for pressure-sensitive and
heat-sensitive recording of a full-color image on a recording sheet
19.
[0030] The color printer 10 is a serial printer comprising a
housing 11, which is rectangular parallelepiped in a longitudinal
direction ("line direction", hereinafter) being perpendicular to a
longitudinal direction of the recording sheet 19.
[0031] A pair of continuous-belt rollers 73 are disposed over a
recording path P, along which the recording sheet 19 is transported
after being inserted in the inlet slit 12 until ejection from the
outlet slit 13, within the housing 11. The rollers 73 are rubber
rollers that tension and drive a continuous belt 70 engaged
therearound. The belt 70 is a film made of, for example, resin, or
a suitable metal, with a width substantially equal to that of the
recording sheet 19. A driving head 64 that generates an image via
selective and localized heat and pressure is disposed over the belt
70, and a rectangular flat platen 45, made of rubber is disposed
parallel to the belt within an area bounded by the belt 70. The
driving head 64 moves in the line direction, driven by a driving
apparatus (not shown). The flat platen 45 extends along the belt
70, in the line direction, so as to support the pressure of the
driving head 64. The surface of the belt 70 is smoother than the
surface of the recording sheet 19, being of normal or plain paper,
and due to the smooth surface, no discharged ink or dye is fixed
thereon and all discharged ink or dye transfer accurately to the
recording sheet 19.
[0032] An ink ribbon 20 having a layer of micro-capsules is
disposed above and in parallel with the belt 70, and has a width
substantially equal to the width of the belt 70. The ink ribbon 20
is wound around a pair of spool spindles 29, and runs from one
spindle to the other as the spindles 29 rotate.
[0033] Under the path P, there are disposed a transfer roller 71
corresponding and parallel to the conveyer roller 73 at the insert
slit 12 side, and a sheet-feeding roller 72 corresponding and
parallel to the conveyer roller 73 at the outlet slit 13 side. The
recording sheet 19 and the belt 70 are vertically supported, by the
rollers 73 and 71 upstream of the driving head 64, and by the
rollers 73 and 72 downstream of the driving head 64 and by a guide
plate (not shown) disposed between the rollers 71 and 72. The
recording sheet 19 is conveyed by the rollers 71, 72 and 73 in the
direction A along the guide plate.
[0034] The spools 29, and the rollers 71, 72 and 73 are driven at
predetermined speeds by a motor, such as a stepping motor or the
like (not shown). The driving apparatus for the driving head 64,
and the motor for the spools 29 and rollers 71 to 73 are controlled
by a controller (not shown), which is mounted on a printed circuit
board 62 on a lower inner surface of the housing 11. A battery 63
for supplying electric power to the components of the color printer
10, such as the motor and the control circuit, is disposed in a
compartment of the housing 11 at a side opposite to the surface
with the outlet slit 13.
[0035] The image transfer apparatus used in the first embodiment of
the color printer is described with reference to FIG. 2. FIG. 2 is
a conceptual view of the printer 10.
[0036] The driving head 64 is provided with thermal heads 31, 32
and 33 which are resiliently biased to contact an interposed
recording sheet 19 at different pressures p1, p2 and p3,
respectively, by means of spring units (not shown). The thermal
head 31 is provided with a plurality of heating elements 34 aligned
in the direction A, which is heated to a predetermined temperature
t1. Similarly, the thermal heads 32 and 33 are provided with a
plurality of heating elements 35 and 36, respectively, which are
heated to respective predetermined temperatures t2 and t3. The
temperatures t1, t2 and t3 are different from one another. The
heating elements 34, 35 and 36 are heated under a control of a
controller (not shown).
[0037] In this case, the thermal heads 31, 32 and 33 correspond to
colors of cyan, magenta and yellow, respectively, but the number of
thermal heads is determined according to a number of the types of
ink or dye to be used.
[0038] The ink ribbon 20 is intermittently conveyed in a direction
shown by an arrow B, and the driving head 64 is driven in a
direction shown by an arrow X. The ink ribbon 20 is pressed by the
thermal heads 31, 32 and 33, with the pressures p1, p2 and p3,
respectively, against the belt 70, which in turn is pressed against
the flat platen 45. The ribbon 20, and thus the belt 70 also, are
selectively and locally heated to the temperatures t1, t2 and t3.
The ink or dye thus discharges from the respective broken
micro-capsules and is transferred to a surface of the belt 70. An
image is thus formed on the belt 70, and hereinafter an area where
the image is formed is called "imaging area" K1. Since the belt 70
is made of resin or the suitable metal, the transferred ink or dye
is not fixed.
[0039] The belt 70 is transported by the conveyer rollers 73
rotating in a direction shown by an arrow C. The imaging area K1 is
moved to "transfer area" K2. The transfer roller 71 rotates in
synchronization with the belt-conveyer rollers 73, shown by arrow
D. At the transfer area K2, the adjacent rollers 71 and 73 press
the interposed recording sheet 19 and the interposed belt 70 with a
pressure higher than a critical breaking pressure P.sub.UL, being
described hereinafter, which is higher than the pressures p1, p2
and p3. Since the surface of the recording sheet 19 is smoothed by
the pressure, the image formed on the belt 70 is uniformly and
reliably transferred to the surface of the recording sheet 19.
Further, one of the rollers 71 and 73 can be heated to a
temperature being higher than the temperatures t1, t2 and t3 by a
heating element disposed in or near the roller (71 or 73), so that
the image formed on the belt 70 is more accurately transferred to
the surface or the recording sheet 19.
[0040] The recording sheet 19 is conveyed in the direction A by the
rollers 71 and 73 rotating in the directions D and C, respectively,
before being introduced to a nip by the guide plate (not shown)
between adjacent rollers 72 and 73, rotating in directions E and C,
respectively, at a synchronous speed, such that the recording sheet
19 is transported to the outlet slit 13 (FIG. 1) and ejected.
[0041] The image formed on the belt is a reflected image of a real
image to be recorded on the recording sheet 19.
[0042] The temperatures t1, t2 and t3 of the heating elements 34,
35 and 36 are set to increase in order, that is, t2 is higher than
t1 and t3 is higher than t2. Since the above serial color printer
10 performs a recording operation as the driving head 64 moves in
the direction X, the temperatures t2 and t3 are readily obtainable
by additional heating of the heating elements 35 and 36,
respectively, thus making thermal control of the heating elements
34, 35 and 36 simple. Conversely, the pressures p1, p2 and p3 are
set to decrease in order, that is, p2 is lower than p1 and p3 is
lower than p2.
[0043] If the recording operation is to be performed during
movement of the driving head 64 in direction X and also in an
opposite direction, the driving head 64 should be pivotally mounted
enabling the order of the heating elements 34, 35 and 36 to be
maintained with respect to a required printing direction of the
driving head 64. It is also possible that the order of the
temperatures t1, t2 and t3 is reversed by changing a connection of
the thermal heads 31, 32 and 33 with a controller (not shown). In
this case, the order of the pressures p1, p2 and p3 for the thermal
heads 31, 32 and 33 are also reversed.
[0044] The ribbon 20 used in the pressure-sensitive and
heat-sensitive color printer 10 is now described in detail with
reference to FIG. 3. FIG. 3 is a cross-sectioned elevational view
of the ribbon 20.
[0045] The ribbon 20 includes a base layer 21 made of, for example,
PET-based resin, a capsule layer 22, and a layer of separation
material 104 made of, for example, teflon-based resin or
silicon-based resin interposed between the base layer 21 and the
capsule layer 22.
[0046] The separation material 104 improves transferability of the
ink or dye to the belt 70 as well as preventing reverse-fixing of
the ink or dye on the base layer 21. The capsule layer 22 is formed
on the layer of separation material 104, by a well-known method not
described herein.
[0047] The capsule layer 22 includes three types of micro-capsules
24, 25 and 26, being, in this case, a cyan type of micro-capsule, a
magenta type of micro-capsule and a yellow type of micro-capsule,
respectively, and is disposed on the layer of the separation
material 104 with a suitable binder or fixing material. The ribbon
20 is disposed adjacent to the belt 70 so that the capsule layer 22
contacts the belt 70 (FIG. 2) during a recording operation.
[0048] In FIG. 3, for the convenience of illustration, although the
capsule layer 22 is shown as having a thickness corresponding to
the diameter of the micro-capsules 24, 25 and 26, in reality, the
three types of micro-capsules 24, 25 and 26 may overlay each other
due to the formation process, and thus the capsule layer 22 may
have a larger thickness than the diameter of a single micro-capsule
24, 25 or 26.
[0049] The three types of micro-capsule are described in detail
with reference to FIGS. 3, 4, 5 and 6. For the material of each
type of micro-capsule (24, 25, 26), a shape memory resin is
utilized. For example, the shape memory resin is represented by a
polyurethane-based-resin, such as polynorbornene, trans-1,
4-polyisoprene polyurethane. As other types of shape memory resin,
a polyimide-based resin, a polyamide-based resin, a
polyvinyl-chloride-based resin, a polyester-based resin and so on
are also known.
[0050] In general, as shown in a graph of FIG. 5, the shape memory
resin exhibits a coefficient of elasticity, which abruptly changes
at a glass-transition temperature boundary Tg. In the shape memory
resin, Brownian movement of the molecular chains is stopped in a
low-temperature area "a", which is less than the glass-transition
temperature Tg, and thus the shape memory resin exhibits a
glass-like phase. On the other hand, Brownian movement of the
molecular chains becomes increasingly energetic in a
high-temperature area "b", which is higher than the
glass-transition temperature Tg, and thus the shape memory resin
exhibits a rubber elasticity.
[0051] The shape memory resin is named due to the following shape
memory characteristic: after a mass of the shape memory resin is
worked into a shaped article in the low-temperature area "a", when
such a shaped article is heated over the glass-transition
temperature Tg, the article becomes freely deformable. After the
shaped article is deformed into another shape, when the deformed
article is cooled to below the glass-transition temperature Tg, the
other shape of the article is fixed and maintained. Nevertheless,
when the deformed article is again heated to above the
glass-transition temperature Tg, without being subjected to any
load or external force, the deformed article returns to the
original shape.
[0052] In the ribbon 20 according to this invention, the shape
memory characteristic per se is not utilized, but the
characteristic abrupt change of the shape memory resin in the
elasticity coefficient is utilized, such that the three types of
micro-capsules 24, 25 and 26 can be selectively broken and squashed
at different temperatures and under different pressures,
respectively.
[0053] As shown in a graph of FIG. 6, a shape memory resin of the
cyan micro-capsules 24 is prepared so as to exhibit a
characteristic elasticity coefficient, indicated by a solid line
(24a), having a glass-transition temperature T1; a shape memory
resin of the magenta micro-capsules 25 is prepared so as to exhibit
a characteristic elasticity coefficient, indicated by a
single-chained line (25a), having a glass-transition temperature
T2; and a shape memory resin of the yellow micro-capsules 26 is
prepared so as to exhibit a characteristic elasticity coefficient,
indicated by a double-chained line (26a), having a glass-transition
temperature T3.
[0054] Note, by suitably varying compositions of the shape memory
resin and/or by selecting a suitable one from among various types
of shape memory resin, it is possible to obtain the respective
shape memory resins, with the glass-transition temperatures T1, T2
and T3.
[0055] As best shown in FIG. 4, the micro-capsule walls 24a, 25a
and 26a of the cyan micro-capsules 24, magenta micro-capsules 25,
and yellow micro-capsules 26, respectively, have differing
thicknesses. The thickness d4 of cyan micro-capsules 24 is larger
than the thickness d5 of magenta micro-capsules 25, and the
thickness d5 of magenta micro-capsules 25 is larger than the
thickness d6 of yellow micro-capsules 26.
[0056] Also, the wall thickness d4 of the cyan micro-capsules 24 is
selected such that each cyan micro-capsule 24 is broken and
compacted under a breaking pressure p1 that lies between a critical
breaking pressure P1 and an upper limit pressure P.sub.UL (FIG. 6),
when each cyan micro-capsule 24 is heated to a temperature t1
between the glass-transition temperatures T1 and T2; the wall
thickness d5 of the magenta micro-capsules 25 is selected such that
each magenta micro-capsule 25 is broken and compacted under a
breaking pressure p2 that lies between a critical breaking pressure
P2 and the critical breaking pressure P1 (FIG. 6), when each
magenta micro-capsule 25 is heated to a temperature t2 between the
glass-transition temperatures T2 and T3; and the wall thickness d6
of the yellow micro-capsules 26 is selected such that each yellow
micro-capsule 26 is broken and compacted under a breaking pressure
p3 that lies between a critical breaking pressure P3 and the
critical breaking pressure P2 (FIG. 6), when each yellow
micro-capsule 26 is heated to a temperature t3 between the
glass-transition temperature T3 and an upper limit temperature
T.sub.UL.
[0057] Note, the upper limit pressure P.sub.UL and the upper limit
temperature T.sub.UL are suitably set in view of the
characteristics of the used shape memory resins.
[0058] As is apparent from the foregoing, by suitably selecting
heating temperatures t1, t2 and t3 and breaking pressures p1, p2
and p3, which should be exerted by the thermal heads 31, 32 and 33
on the ribbon 20, it is possible to selectively break and squash
the cyan, magenta and yellow micro-capsules 24, 25 and 26.
[0059] For example, the heating temperature t1 and breaking
pressure p1 fall within a hatched cyan area C (FIG. 6), defined by
a temperature range between the glass-transition temperatures T1
and T2 and by a pressure range between the critical breaking
pressure P1 and the upper limit pressure P.sub.UL, thus only the
cyan type of micro-capsule 24 is broken and squashed, thereby
seeping the cyan ink or dye 24b (FIGS. 3 and 4). Also, the heating
temperature t2 and breaking pressure p2 fall within a hatched
magenta area M, defined by a temperature range between the
glass-transition temperatures T2 and T3 and by a pressure range
between the critical breaking pressures P2 and P1, thus only the
magenta type of micro-capsule 25 is broken and squashed, thereby
seeping the magenta dye or ink 25b (FIGS. 3 and 4). Further, the
heating temperature t3 and breaking pressure p3 fall within a
hatched yellow area Y, defined by a temperature range between the
glass-transition temperature T3 and the upper limit temperature
T.sub.UL and by a pressure range between the critical breaking
pressures P2 and P3, thus only the yellow type of micro-capsule 26
is broken and squashed, thereby seeping the yellow dye or ink 26b
(FIGS. 3 and 4).
[0060] Accordingly, when the heating temperatures t1, t2 and t3 of
the heating elements 34, 35 and 36 are suitably controlled in
accordance with digital color image-pixel signals: digital cyan
image-pixel signals, digital magenta image-pixel signals and
digital yellow image-pixel signals inputted to the color printer
10, it is possible to form a color image on the recording sheet 19
on the basis of the digital color image-pixel signals.
[0061] As mentioned above, in the first embodiment, the image is
formed once on the belt 70 by the ink or dye 24b, 25b and 26b
discharged from the micro-capsules 24, 25 and 26 selectively broken
by the thermal heads 31, 32 and 33, applying localized pressures
p1, p2, p3 and selective heating at temperatures t1, t2 and t3. The
image on the belt 70 is transferred onto the recording sheet 19 by
pressing the belt 70 against the recording sheet 19. Therefore, the
image is transferred twice, being from the ink ribbon 20 to the
belt 70 and from the belt 70 to the recording sheet 19.
[0062] If it is necessary to further smooth an uneven surface of
the recording sheet 19 in order to improve the transferability of
the ink or dye 24b, 25b and 26b, the smoothing can be performed by
pre-coating. However, due to the complicated nature of the
pre-coating operation, it is preferable to supply a high pressure
between rollers 71 and 73 (FIG. 2) to improve a surface condition
for the transfer of the ink or dye 24b, 25b and 26b to the
recording sheet 19. Since the transfer of the ink or dye 24b, 25b
and 26b from the belt 70 to the recording sheet 19 is independent
of the forming of the image on the belt 70, the pressure for a
high-accuracy transfer of the image from the belt 70 to the
recording sheet 19 is not limited by the critical breaking
pressures P3 to P.sub.UL of the capsules 24, 25 and 26.
[0063] If excessive pressure were supplied to the ribbon 20,
selective breaking of the micro-capsules would be impossible, and
an exact image would not be producible.
[0064] In the first embodiment, the recording sheet 19 can be
pressed with a much higher pressure than the critical breaking
pressure P.sub.UL when the image is transferred from the belt 70 to
the recording sheet 19, so the unevenness of the recording sheet is
sufficiently smoothed and the transferability becomes higher. Since
the surface of the belt 70 is smoother than that of the recording
sheet 19, the pressures p1, p2 and p3 applied to the capsule layer
22 are accurately determined and preset, allowing the image to be
reliably generated on the belt 70.
[0065] Therefore, the transfer performance is high due to good
transferability and accurate pressure application regardless of a
surface condition of a recording sheet, and a high quality image is
reproducible.
[0066] A second embodiment is described with reference to FIGS. 7
and 8. The second embodiment only differs from the first embodiment
in that the image is transferred to the recording sheet 19 via a
roller platen 74, and as such descriptions of the other identical
portions are omitted.
[0067] FIG. 7 is a conceptual view of an image transfer apparatus
used in a color printer of the second embodiment. The color printer
is a line printer. There is provided a thermal head 30, extending
over substantially a width of the recording sheet 19, having a
plurality of heating elements 37, 38 and 39 at a bottom surface
thereof. The heating elements 37, 38 and 39 are linearly aligned in
respective parallel rows in the lateral (line) direction of the
recording sheet 19. The temperatures of the heating elements 37, 38
and 39 are set to be the glass-transition temperatures t1, t2 and
t3 of the micro-capsules 24, 25 and 26, similarly to the first
embodiment.
[0068] Under and in contact with the heating elements 37, 38 and
39, an ink ribbon 20 is disposed in the longitudinal direction of
the recording sheet 19. The ink ribbon 20 is wound on a pair of
spools 29 extending in the line direction of the recording sheet
19, and is conveyed in direction B from one spool 29 to the other
spool 29, similar to the first embodiment. The roller platen 74 is
provided under the ribbon 20, extending in the line direction of
the recording sheet 19, and is made of a hard rubber coated with a
film of resin, similar to that used in the first embodiment. The
roller platen 74 may alternatively be a metal roller with a smooth
surface.
[0069] An image transfer roller 75 is disposed parallel to and
adjacently below the roller platen 74. The recording sheet 19, when
interposed, is pressed by the image transfer roller 75 against the
roller platen 74, and is transported in the direction A by the
rotational movements of the transfer roller 75 and the roller
platen 74. An electric motor, such as a stepping motor (not shown),
drives the roller platen 74 in a rotational direction F, which in
turn drives the transfer roller 75 in a direction G via frictional
traction forces generated between the rollers 74, 75 and the
surfaces of the recording sheet 19.
[0070] FIG. 8 is an elevational view of the roller platen 74 and
the thermal head 30. The thermal head 30 is tangentially aligned to
an outer circumferential surface of the roller platen 74, the rows
of heating elements 37, 38 and 39 being parallel to the
circumferential surface of the roller platen 74. The rows of the
heating elements 37 is positioned vertically above a rotational
axis of the roller platen 74, and the row of the heating elements
38 and 39 are coplanar to the heating elements 37 horizontally
arranged in this order offset from vertically above the rotational
axis of the roller platen 74. The distance from the row of heating
elements 37 to the heating elements 39 is greater than the distance
to the row of heating elements 38. The clearance between the
thermal head 30 and the circumferential surface of the roller
platen 74 increases from the position of the heating element 37 to
the position of the heating element 39, and as the distance
decreases, the pressure supplied to the interposed ink ribbon 20 by
the heating elements 37, 38 and 39 increases. The pressure p1
applied to the ink ribbon 20 by the heating element 37 is higher
than the pressure p2 applied by the heating element 38, and the
pressure p2 applied by the heating element 38 is higher than the
pressure p3 applied by the heating element 39. The pressures p1, p2
and p3 identically correspond to the breaking pressures p1, p2 and
p3 of the micro-capsules 24, 25 and 26, similar to the first
embodiment.
[0071] As shown in FIG. 7, the ink ribbon 20 is heated and pressed
between the heating elements 37, 38, 39 and the roller platen 74 in
an imaging area K3. The micro-capsules 24, 25, 26 held on the
ribbon 20 are selectively heated to the glass-transition
temperatures t1, t2, t3 and pressed by the breaking pressures p1,
p2, p3, so that the ink or dye 24b, 25b, 26b is discharged. The ink
or dye 24b, 25b, 26b is transferred to the roller platen 74 as an
image which is then displaced to a transfer area K4 as the roller
platen 74 rotates. The image is thus transferred to a recording
sheet 19, which is interposed and pressed between the transfer
roller 75 and the roller platen 74 with a pressure higher than the
critical breaking pressure P.sub.UL of the micro-capsules 24, 25,
26.
[0072] Similarly to the first embodiment, the ink or dye 24b, 25b,
26b is discharged from the micro-capsules 24, 25, 26 due to the
localized pressure application and selectively controlled heating
in accordance with inputted digital image-pixel signals, and thus
the image is readily reproducible. The image is transferred via two
stages, being from the ink ribbon 20 to the roller platen 74 and
from the roller platen 74 to the recording sheet 19. Since the
recording sheet 19 is smoothed by the pressure between the rollers
74 and 75, the transferability is good. The surface of the roller
platen 74, being much smoother than the surface of the recording
sheet 19, enables a precise predetermined setting of the pressures
p1, p2 and p3 supplied to the capsule layer 22. A fine image can
thus be transferred regardless of the initial unevenness of the
surface of the recording sheet 19. Further, the transfer roller 75
can be heated to a temperature being higher than the temperatures
t1, t2 and t3 by a heating element which is disposed in or near the
transfer roller 75, so that the image is transferred accurately to
the surface of the recording sheet 19.
[0073] Alternatively, in order to simplify a structure, the belt 70
and pair of the belt-conveyer rollers 73 (FIG. 2) of the first
embodiment may be substituted for the roller platen 74 in the
second embodiment. Thus a printing speed is higher due to the
linear arrangement of the heating elements 37, 38, 39 in the line
direction across the width of the recording sheet 19, and due to
the decreased number of components necessary.
[0074] Further, the construction of the second embodiment can also
be applied to a serial printer, such as that of the first
embodiment, by substituting the thermal head 30 for a driving head
60, as shown as modification of the second embodiment in FIG. 9.
The roller platen 74, which is intermittantly rotated by a one
printing line pitch by the aforementioned motor to allow a line by
line serial printing operation to be performed, is positioned
beneath the driving head 60, so that the driving head 60 is in
contact with the upper surface of the ink ribbon 20. The driving
head 60 is movable in a direction H, similar to the line direction
X in the first embodiment. The driving head 60 is provided with
thermal heads 81, 82 and 83, each of which has a plurality of
heating elements 84, 85 and 86, respectively, which are linearly
aligned in the direction H. Thus, a printing operation can be
performed serially in accordance with the second embodiment.
[0075] FIG. 10 shows a third embodiment in which an image is
generated first on the ink ribbon 20. Elements and constructions
similar to those of the previous embodiments have like references
and descriptions are omitted. FIG. 10 is a conceptual view of an
image transfer apparatus used in a color printer. A thermal head
90, an ink ribbon 20 and a platen roller 77 are disposed under the
transport path P (FIG. 1). The thermal head 90 is rectangular
parallelepiped, extending longitudinally in the line direction of
the recording sheet 19. The thermal head 90 is disposed normal to a
printing surface of the recording sheet 19, and includes three rows
of plural heating elements 87, 88 and 89 linearly aligned parallel
to the line direction of the recording sheet 19.
[0076] The ink ribbon 20 is provided with the layer of
micro-capsules 22 and laterally extends substantially across the
width of the recording sheet 19. The thermal heads 87, 88 and 89
contact the width of the ink ribbon 20, similarly to the second
embodiment. The ribbon 20 is wound on a pair of spool spindles 29,
disposed parallel to the line direction with the thermal head 90
interposed therebetween. The ribbon 20 is spooled in an
image-transfer direction J, being perpendicular to both the line
direction and the transport direction A (FIG. 1).
[0077] The roller platen 77 extends in the line direction, parallel
and adjacent to the rows of heating elements 87, 88 and 89. The
outer surface of the roller platen 77, being in resilient contact
with the ribbon 20 under varying pressures due to the tangential
alignment of the thermal head 90, similar to the second embodiment,
is coated with a releasant for preventing any adhesion or transfer
of the ink or dye 24b, 25b, 26b from the micro-capsules 24, 25 and
26. The ink ribbon 20 is pressed by the heating elements 87, 88 and
89 against the roller platen 77 with breaking pressures p1, p2 and
p3, set by varying the distance between the thermal head 90 and the
circumferential surface of the roller platen 77, due to the
tangential positioning of the thermal head 90 with respect to the
roller platen 77. The roller platen 77 rotates in a direction I,
synchronous with the rotation of the spools 29, aiding conveyance
of the ribbon 20 in image-transfer direction J.
[0078] An image transfer roller 76 is disposed above the path P,
with rotational axes of the spools 29 and the image transfer roller
76 being parallel to each other and in vertical alignment. The
recording sheet 19 is pressed by the transfer roller 76 against the
ink ribbon 20 at a transfer area K5. The transfer roller 76 rotates
in a direction H, due to frictional traction forces between the
spool 29, surfaces of the recording sheet 19 and roller 76,
enabling cooperative transportation of the recording sheet 19 in
the direction A. The ink ribbon 20 is selectively and locally
heated to temperatures t1, t2, t3 by the heating elements 87, 88
and 89 in accordance with inputted digital image-pixel signals,
while being locally pressed with breaking pressures p1, p2, p3 by
the heating elements 87, 88 and 89, respectively, against the
platen roller 77. As in the previous embodiments, the
micro-capsules 24, 25, 26 are selectively broken, discharging the
ink or dye 24b, 25b, 26b. The ink or dye 24b, 25b, 26b does not
adhere to the platen roller 77 due to the releasant coating thereon
and remains on the ribbon 20.
[0079] The ink ribbon 20 complete with the selectively and locally
discharged ink or dye 24b, 25b, 26b is conveyed in the
image-transfer direction J to the area K5, so as to be transferred
to the recording sheet 19. The recording sheet 19 is pressed, at
the area K5 by the transfer roller 76, against the ink ribbon 20 at
a normal ambient temperature, such as room temperature
(approximately 25.degree. C.) and under a pressure not greater than
the critical breaking pressure P.sub.UL (FIG. 6). The image on the
ribbon 20 is thus accurately and reliably transferred onto the
recording sheet 19.
[0080] In the third embodiment, due to the ink or dye 24b, 25b and
26b being selectively and locally discharged from the
micro-capsules 24, 25 and 26, the image is accurately and easily
reproducible. The image is transferred via two stages, being the
generation of the image on the ink ribbon 20, and the transfer of
the image from the ink ribbon 20 to the recording sheet 19. One to
the second stage occurring at generally room temperature that is
lower than the glass-transition temperature T1, the unbroken
micro-capsules 24, 25 and 26 on the capsule layer 22 are not broken
on transfer of the image, even when subjected to a pressure at area
K5 that is in the region of the critical breaking pressures P3 to
P.sub.UL, preferably in the region of the critical breaking
pressures P1 to P.sub.UL. Further, due to the smooth outer surface
of the roller platen 77 and precisely set pressures p1, p2 and p3
applied by the thermal head 90, an accurate discharge of the dye or
ink 24b, 25b and 26b on the ink ribbon 20 can be obtained, which
translates into a high-quality image being formed on the recording
sheet 19.
[0081] A modified construction of the third embodiment can be
applied to a serial printer, such as the color printer 10 of FIG.
1, when the thermal head 90 is substituted for a driving head,
similarly to the second embodiment. The image formed on the ink
ribbon 20 is also a real image viewed from the thermal head 90,
which is the same as the image recorded on the recording sheet
19.
[0082] Finally, it will be understood by those skilled in the art
that the foregoing description is of preferred embodiments of the
device, and that various changes and modifications may be made to
the present invention without departing from the spirit and scope
thereof.
[0083] The present disclosure relates to subject matters contained
in Japanese patent Application No.10-20324 (filed on Jan. 16, 1998)
which is expressly incorporated herein, by reference, in its
entirety.
* * * * *