Multi-pass thermal printer

A thermal printer accepting an ink ribbon cartridge includes a chassis, a thermal head secured to the chassis and a platen roller which is rotatably supported in the chassis and swingably movable relative to the thermal head. The platen roller is rotated by a first platen driving mechanism and is moved toward and away from the thermal head by a second platen driving mechanism. When the platen roller is moved to contact the thermal head via an ink ribbon intervened therebetween, an image is printed on a printing medium fed between the platen roller and the ink ribbon. The printer accomplished aligned overprinting on the printing medium via a paper supply mode, a printing mode, a paper retract mode and a paper discharge mode effected by the first and second platen driving mechanisms.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to a thermal printing apparatus. 
Particularly, the invention relates to a printer which prints different 
parts of an image over a previously printed part such as in a four color 
printing process or the like. Specifically, the present invention relates 
to a color video printer. 
2. Description of the Prior Art 
Thermal head type printers are well known in the art in which a thermal 
head is pressed against a sheet of material supported on platen roller for 
printing an image on the material. In order to release heat generated by 
energization of the thermal head, a radiator, or heat radiating fin is 
provided on a rear portion of the thermal head. Generally, the thermal 
head is mounted on a shaft so as to be enabled to move in and out of 
contact with the platen roller. Upon printing, the thermal head is 
sufficiently heated so that an image is printed on the sheet. Heat 
generated in the thermal head is radiated by the heat radiating fin within 
a housing of the apparatus. An example of such a printing apparatus, is 
disclosed in Japanese Utility Model application (First Publication) No. 
62-45145. 
However, such a know printing apparatus employs a motor-driven cooling fan 
or the like in order to exhaust air heated by heat radiation from the 
printer housing. Therefore, the apparatus must be of a size for 
accommodating such a fan and manufacturing costs and complexity become 
increased. Further, the above type of printer requires a two reel type ink 
arrangement for positioning of an ink cartridge, further increasing size 
of the printer. 
SUMMARY OF THE INVENTION 
It is therefore a principal object of the present invention to overcome the 
drawbacks of the prior art. 
It is a further objection of the invention to provide a printer which has 
efficient heat discharge characteristic and which operates with high 
reliability. 
It is also an object of the present invention to provide a video printer 
which is compact in size and which may be made thinner, and more 
lightweight while reducing manufacturing costs. 
In order to accomplish the aforementioned and other objects, a printer is 
provided, comprising: a housing, a chassis forming a base for the housing, 
a thermal head fixedly mounted in the housing, a platen roller rotatably 
supported in the chassis and being movable relative to the thermal head, 
first platen driving means swingably movable of the platen to second third 
and fourth orientations relative the thermal head, second platen driving 
means driving the plate to rotate in clockwise an counterclockwise 
directions association with movement of the first platen driving means a 
receptacle for receiving an ink ribbon cartridge containing and ink 
ribbon, extracting means, extracting the ink ribbon from the ink ribbon 
cartridge, ink ribbon guide means guiding the ink ribbon extracted by the 
extracting means around the platen so as to be between the platen and the 
thermal head, take-up means for retaining ink ribbon as ink ribbon is 
extracted from the ink ribbon cartridge according to printing and chucking 
operation by the printer, control means for controlling operation of the 
first and second platen driving means, the ink ribbon guide means and the 
take-up means for effecting printing operation on a sheet printing medium 
such that aligned overprinting is accomplished on the printing medium 
according to movement of the printing medium via the first through fourth 
positions of the first platen driving means in conjunction with rotation 
by the second platen driving means the aligned overprinting comprising at 
least a first printing operation corresponding to one extracted position 
of the ink ribbon cartridge and a second printing operation on the 
printing medium in alignment with the first printing operation and 
corresponding to another extracted position of the ink ribbon cartridge, 
the first platen driving means effecting separation between the printing 
medium and the thermal head between the first and the second printing 
operations.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, particularly to FIG. 1, a thermal transfer 
type color video printer 1 according to the invention, is shown. The color 
video printer 1 includes a rectangular casing 2, left and right side 
plates 4 and 6 disposed at opposite ends of the casing 2, and a 
channel-shaped main chassis 3 connected at opposite ends thereof to the 
left and right side plates 4 and 6. The main chassis 3 has a bottom wall 
and front and rear walls oppositely and upwardly extending from the bottom 
wall. Between the front and rear walls of the chassis 3, the left and 
right side plates 4 and 6 are extended. Supporting bars 7 and 8 are 
disposed between the left and right side plates 4 and 6 and fastened 
thereto by screws 9. 
A left inner plate 5 is disposed proximate, and substantially parallel to 
the left side plate 4 and extends between the front and rear walls of the 
main chassis 3. A platen roller 21, formed of a resilient material such as 
rubber, is rotatably disposed between the left inner plate 5 and the right 
side plate 6, within the casing 2, for accepting a sheet 10 of a material 
to be printed on, such as paper, for example. For guiding the sheet 
material 10 to the platen roller 21, a guide plate 11 is provided. Below 
the guide plate, extending parallel to the platen roller 21, a 
substantially cylindrical, open-ended ink ribbon cartridge receptacle 13 
is mounted in a forward portion of the interior of the casing 2. Further, 
a pair of sheet guide rollers. 12a, 12a, also made of a resilient 
material, are rotatably disposed on the front side of the sheet guide 
plate 11 so that a sheet 10, disposed on the guide plate 11 and which 
passes between the sheet guide rollers 12a, 12a, is fed to the platen 
roller 21 by rotation of the sheet guide rollers 12a, 12a. A guide roller 
12b is disposed at the end of the guide plate closest to the platen roller 
21 in the manner shown in FIG. 1. A sheet discharge guide plate 14 is 
disposed over the sheet guide plate 11 and guides the sheet 10, after 
traveling around the platen roller 21, to discharge the sheet 10 outside 
of the printer casing 2. FIGS. 21 and 25 show the positions of the guide 
rollers 12a, 12a in a state of guiding a sheet 10 to the platen roller 21 
and after guiding a sheet 10 to the platen roller 21, respectively. 
As seen in FIG. 1, a sub-chassis 15 is attached to the main chassis 3. The 
sub-chassis 15 is substantially L-shaped in lateral cross section so as to 
extend along a rear bottom corner portion of the main chassis 3. A thermal 
head 16 is attached to the sub-chassis 15 by set screws, or the like, so 
as to upwardly incline at a predetermined angle relative to the bottom 
wall of the main chassis 3 and longitudinally extends along the rear 
bottom corner portion of the main chassis 3. The sub-chassis 15 serves as 
a mount for installation of the thermal head 16, and the main chassis 3 
serves as a heat radiator for releasing heat generated by the thermal 
head, from the casing 2. 
As seen in FIG. 2, a take-up reel shaft receiving portion 19 forms a 
support axis for a take-up reel 17 for used ink ribbon 94 unwound from an 
ink ribbon cartridge 90 in the ink ribbon cartridge receptacle 13. The 
take-up reel shaft receiving portion 19 is attached to the right side 
plate 6. At the other end of the take-up reel 17, proximate the left inner 
side plate 5, a rotatable take-up reel support projection 69 is interposed 
between the left inner side plate 5 and the take-up reel 17, so as to 
oppose the take-up reel shaft receiving portion 19. The take-up reel 17 
extends longitudinally between the take-up reel shaft receiving portion 19 
and the support projection 69, parallel to the platen roller 21 and 
includes a cylindrical body portion 17a therearound and has, at a 
mid-portion of its peripheral surface a recess 17b. As best seen in FIGS. 
3 and 10 the recess 17b mounts a substantially L-shaped claw member 18 is 
mounted. As shown in FIG. 3, the claw member 18 is biased by a coil spring 
18a to project outwardly from the recess of the body portion 17a so as to 
be engaged with a through hole 95a of the ink ribbon 94, for chucking the 
ink ribbon 94 upon loading of a new ink ribbon cartridge 90 in the ink 
ribbon cartridge receptacle 13. The platen 21 is associated with a platen 
driving mechanism 30, and a gear assembly 20 for driving the platen in 
both clockwise and counterclockwise directions for effecting printing on a 
sheet 10 by bringing the sheet into contact with the thermal head 16 by 
swinging action of the platen 21. 
As seen in FIGS. 3 and 7 the platen driving mechanism comprises a shaft 31 
journaled on the left inner and right side plates 5 and 6, and left and 
right support arms 32, 32 which are rotatably supported by the shaft 31 in 
the printer casing 2. Between the left and right support arms 32, 32, a 
support shaft 22 supporting the platen roller 21 is rotatably mounted. 
Each of the support arms 32, 32 is of a substantially triangular shape. 
The shaft 22 of the platen roller 21 extends through and beyond the plane 
of each of the supports arms 32 such that ends thereof project slightly 
outwardly from the support arms 32, 32. The ends of the shaft 31 extend 
through portions of the triangular shape of each of the support arms 32, 
32 and are respectively mounted in the left inner side plate 5 and the 
right (inner) side plate 6. First and second corner portions of the lower 
part of the triangular shape of the support arms 32, 32 are provided with 
elliptical openings 32a and 32b respectively. Upper and lower pinch 
rollers 45a, 45 extend substantially parallel to the shaft 22 of the 
platen roller 21 and pass through the elliptical openings 32a and 32b 
opposingly provided in each of the support arms 32, 32. The upper and 
lower pinch rollers 4S, 45 are supported in the elliptical openings 32a 
and 32b such that both ends thereof are slidable in a radial direction. 
The pinch rollers 45, 45 urge the sheet 10 against a circumferential 
surface of the platen roller 21. Both ends of each pinch roller 45 are 
connected via resilient means, in this ease, coil springs 46, 46 to each 
end of the platen roller 21 support shaft 22, projected outwardly from an 
outer side of each of the support arms 32. The support arms 32, 32 are 
positioned such that the upper corners of the triangular shapes of the 
support arms 32, 32 are spaced forwardly of the lower corners thereof 
having the elliptical openings 32a, 32b. The forwardly spaced upper corner 
of each of the support arms 32, 32 supports an end of a bar 33, extending 
in parallel with the support shaft 22 of the platen roller 21. 
Substantially, L-shaped sub-support arms 34, 34 are rotatably mounted on 
both ends of the shaft 31 so as to project from the support arms 32, 32. 
Each of the sub-support arms 34, 34 has one end mounted on the shaft 31 
and the other end supporting a bar 35. The bar 35 passes through each of 
the sub-support arms and is securely supported at both ends thereby. Each 
end of the bar 35, projecting outwardly From each of the sub-support arms 
34, 34 is connected via coil springs 36, 36 to respective ends of the bar 
33 projecting outwardly from the support arms 32, 32. 
As seen in FIGS. 2, 3 and 7, the platen roller driving mechanism 30 also 
includes a drive shaft 37 which is rotatably supported at both ends 
thereof by the left inner side plate 5 and the right side plate 6, 
substantially parallel to the bar 35 of the sub-support arms 34, 34. The 
drive shaft 37 and the bar 35 are connected with each other via an oval 
shaped link member 38. The link member 38 has an end secured to a 
mid-portion of the drive shaft 37 and a tapered end having an elongated 
hole through which the bar 35 passes. A driving arm 39 is mounted on the 
drive shaft 37 adjacent and inside of the right side plate 6. The driving 
arm 39 has one end secured to the driving shaft 37 and the other end 
provided with a pin 40 which extends outwardly therefrom so as to project 
from an outer face of the right side plate 6. On the outer face of the 
right side plate 6 is mounted a shaft 42 on which a cam gear 41 is 
rotatably supported (see FIGS. 1 and 2). As seen FIGS. 1 and 2, the cam 
gear 41 has, on an inner face thereof, a first cam groove 41a into which 
the pin 40 is fitted to act as a cam follower. The cam gear 41 is engaged 
with a driving gear 44 driven by a motor 43 which is secured to an upper 
portion of the outer face of the right side plate 6. 
As seen in FIGS. 4 and 7, a platen gear 23 is secured to the left side of 
the platen roller 21. The platen gear 23 is associated with a platen 
rotating mechanism 20, which is essentially a gear assembly as will be 
described hereinbelow. 
Referring to FIGS. 8 and 9, the gear 23 is opposed to an inner face of the 
left support arm 32. The platen gear 23 is operably associated with the 
gear assembly of the platen rotating mechanism 20 arranged inside the left 
inner plate 5. The platen rotating mechanism 20 comprises first through 
sixth gears 24 to 29. The first gear 24 is rotatably mounted on the shaft 
31 arranged between the support arms 32, 32 and is engaged with the platen 
gear 23 fixed on the side of the platen roller 21. The second gear 25 is 
rotatably supported on a capstan shaft 50 extending longitudinally and 
disposed over an inlet/outlet 13b of the ink ribbon cartridge receptacle 
13 through which the ink ribbon 94 passes. The second gear 25 is engaged 
with the first gear 24 and the third gear 26. The third to sixth gears 26 
to 29 are rotatably supported on respective shafts disposed on an inner 
face of the left inner plate 5. The sixth gear 29 is engaged with a 
driving gear 47a disposed inside the left inner plate 5. The driving gear 
47a is connected to a motor 47 mounted on an outer face of the left inner 
plate 5, so that the gear assembly comprising the platen rotating 
mechanism 20 is rotated via the driving gear 47a by the motor 47. 
According to the above construction, the platen driving mechanism 30 
enables rotation of the platen roller 21 while the platen is moved toward 
and away from the thermal head 16. 
The ribbon cartridge receptacle 13 is arranged between the left inner plate 
5 and the right side plate 6 with an opening for insertion of a ribbon 
cartridge 90 facing in an upward direction. The capstan shaft 50 is 
rotatably positioned near the opening 13b of the ribbon cartridge 
receptacle 13 so as to contact a pinch roller 51 for cooperatively 
rotating together for extracting the ink ribbon 94 From the ink ribbon 
cartridge 90 held in the ribbon cartridge receptacle 13. In addition, a 
supply reel mount 52 operatively engages a supply reel 93 within the 
ribbon cartridge 90 for rotating the supply reel 98, extracting the ink 
ribbon 94 for effecting printing operation. The supply reel mount 52 and 
the capstan shaft 50 are driven by a motor 53 mounted between the left 
side plate 4 and the left inner plate 5. As seen in FIG. 4, a driving gear 
54 is driven by the motor 53 and engaged with a first intermediate gear 55 
disposed on the outer face of the left inner plate 5. Rotation of the 
first intermediate gear 55 is transmitted to a second intermediate gear 56 
disposed on a inner face of the left side plate 4. The second intermediate 
gear 56 is engaged with a gear 57 secured to an end of the capstan shaft 
50. As a result, the capstan shaft 50 is rotated by the motor 53. As shown 
in FIG. 2, intermediate gears 58, 58 are disposed on inner and outer faces 
of the left inner plate 5, respectively. As shown in FIG. 4, the gear 58 
on the outer face of the left inner plate 5 is engaged with the first 
intermediate gear 55 while the gear 58 on the inner face of the left inner 
plate 5 is engaged with a gear 59 secured to the ink ribbon supply reel 
mount 52. Thus the ink ribbon supply reel mount 52 is also driven by the 
motor 53. 
Referring to FIG. 6, the pinch roller 51, disposed between the left inner 
plate 5 and the side plate 6 is positioned near a shaft 60 to which a 
oscillating plate 61 is attached which is movable in upward and downward 
directlobs. The edge portion of the oscillating plate 61 is provided with 
a pair of cut-out portions for accommodating ribbon guide portions 91a, 
91a of the ink ribbon cartridge 90. Corresponding to the cut-out portions 
of the oscillating plate 61, a pair of shaft receiving plates 61a, 61a are 
provided, the shaft receiving plates 61a, 61a rotatably mount the pinch 
roller 51 therebetween. Further, a coil spring 60a is provided for biasing 
the oscillating plate 61 in the upward direction. 
Referring to FIGS. 1 and 15, the oscillating plate 61 is provided, at its 
right end, with an arcuate rack 62. The rack 62 is engaged with a rack 64a 
which is formed on a lower-front portion of a slider 64. The slider 64 is 
substantially vertically slidable along pins 63, 63 which are projected 
inwardly from an inner face of the right side plate 6. As seen in FIG. 15, 
a sliding plate 65 is arranged adjacent the rack 64a to be slidable in a 
substantially vertical direction along the pins 63, 63. Both the slider 64 
and the slide plate 65 have corresponding longitudinally extended openings 
64d, 64d and 65d, 65d respectively for receiving the pins 63, 63. The 
sliding plate 65 is penetrated, at an upper end portion thereof, with a 
pin 66 having ends 66a, 66b projecting therefrom in both outward and 
inward directions respectively (upward and downward directions in FIG. 
15). The outward facing end 66a of the pin 66 passes through an enlongate 
opening 6a of the right side plate 6 so as to engage a second cam groove 
41b which is formed on an inner face of the cam gear 41. On the other 
hand, the inward facing end 66b of the pin 66 is connected to a lower end 
portion 64b of the slider 64 via a coil spring 67. The slider 64 and the 
slide plate 65 are held to the side plate 6 via washers 68, 68 attached 
over the pins 63, 63. Also, at a central upper portion of the pin 66, a 
flange 66c is provided. The flange 66c serves as a limiter, contacting an 
upper edge 64c of the slider 64, for establishing an uppermost position of 
the slider 64 and the slide plate 65. 
As seen in FIG. 3, a bracket 70 is disposed on the bottom wall of the main 
chassis 3 so as to be positioned below the platen roller 21. An ink ribbon 
guide plate 71 is pivotally supported around a pin disposed on the bracket 
70. The guide plate 71 has a top end 71a biased downwardly by a spring 72. 
A lower ink ribbon guide 73, biased in the upward direction by a spring 
74, is attached to the bracket 70. The lower ink ribbon guide is provided 
with an ink ribbon guide roller 75 which is rotatably supported at a top 
end of the lower ink ribbon guide 73. An upper ink ribbon guide 77 is 
rotatably supported on a shaft 76 at a position over the thermal head 16 
and has an ink ribbon guide roller 79 near a top end thereof. The upper 
ink ribbon guide 77 is biased toward the platen roller 21 by a spring 78 
such that the ink ribbon guide roller 79 is urged against the 
circumferential surface of the platen roller 21. 
Furthermore, as seen in FIGS. 10, 11 and 12, on the shaft 76 an ink ribbon 
guide control plate 80 is supported. The ink ribbon guide control plate 80 
has a distal end portion 80b and a protrudent portion 80a at a lower-right 
portion thereof, as shown in FIG. 1. The protrudent portion 80a cooperates 
with a circumferential face of a cam projection 41c projecting outwardly 
from an outer face of the cam gear 41. The ink ribbon guide control plate 
80 is biased toward the body portion 17 of the take-up reel 17 by a spring 
(not shown). Backtensioning provided by the spring allows the ribbon guide 
control plate 80 to remain in pressing contact with the ink ribbon 94 as 
it is wound around the cylindrical body portion 17a of the take-up reel 
17, as the diametric profile of the outer circumference thereof is changed 
due to winding of the ink ribbon 94. As can be seen in FIGS. 11 and 12, 
shaft 17d of the take-up reel 17 projects from one side of the take-up 
reel 17, while a U-shaped indentation 17c is formed in the other end 
thereof. 
As shown in FIGS. 13 and 14, the left end of the take-up reel 17, provided 
with the U-shaped indentation 17c is positioned such that the take-up reel 
support projection 69 is inserted into the U-shaped indentation 17c to 
establish a locking fit therein so as to enable co-rotation of the support 
projection 69 and the take-up reel 17. A gear 81 is rotatably disposed 
around the take-up reel support projection 69 for rotation therewith. The 
take-up reel support projection 69 and the gear 81 are coaxially disposed 
on a shaft 86 which is mounted at one end to the left inner plate 5. A 
flange portion 69a is provided a an end of the take-up reel support 
projection 69 proximate the left inner plate 5 and a coil spring 87 is 
disposed around the take-up reel support projection 69 for biasing the 
gear 81 in a direction toward the take-up reel 17. The face of the gear 81 
facing a flange 17e of the take-up reel 17 is provided with a pad 88, of 
felt material or the like, for protecting the gear 81 and the take-up reel 
17 from damage when the take-up reel 17 is removed from the printer. 
Referring to FIG. 13, the gear 81 is engaged with a gear 82 which is 
mounted on a shaft 89 and held at a position away from the right side 
plate 6 by a spacer 89a. Also mounted on the shaft 89 on the outer face of 
the right side plate 6 a gear 83 is secured for co-rotation with the gear 
82, the gear 83 engages a driving gear 85 driven by a motor 84 mounted on 
an outer side of the right side panel 6. Thus the driving gear 85, drives 
the gears 83 and 82 via the motor 84 to turn the gear 81 for controlling 
rotation of the take-up reel 17. 
The take-up reel shaft receiving portion 19 comprises spacer portions 19d, 
19d separating an upper plate 19b and a lower plate 19a, the upper and 
lower plates 19a and 19b are secured together with the spacers 19d, 19d 
interposed therebetween by screws 19c. The take-up reel shaft receiving 
portion 19 is mounted to the inner face of the right side plate 6 by 
screws, or the like. It will be noted that, alternatively the take-up reel 
shaft receiving portion 19 may be integrally formed of a single material, 
or that the spacer portions 19d may be formed as part of the upper or 
lower plates 19a, 19b. 
As best seen in FIG. 14, for removal operation of the take-up reel 17, the 
take-up reel 17 may be pushed in a direction toward the left inner plate 
5, against the force of the spring 87 biasing the gear 81, thus displacing 
the take-up reel 17 in that direction and freeing the support projection 
17d from the take-up reel shaft receiving portion 19. The end of the 
take-up reel 17 having the support projection 19 may then be lifted from 
the printer apparatus and the take-up reel 19 may be easily extracted 
therefrom. It will be noted that as the end of the take-up reel 17 having 
the support projection 17d is lifted, the angular relationship between the 
support projection 69 and the U-shaped indentation 17c is changed and the 
flange 17e is pressed against the pad 88, further displacing the gear 81 
in a direction toward the right side plate 6 and easy removal of the 
take-up reel 17 is facilitated. 
As seen in FIGS. 17 and 18, light sensors 97, 98 are provided in the 
printer casing 2 at positions above and below the platen roller 21 for 
detecting markers (not shown) provided on the ink ribbon 94 for assuring 
accurate positioning of the ink ribbon 94 in printing operation. In FIG. 
18 the markers are represented by broken line portions of the ink ribbon 
94. If for example, the ink ribbon is cut or broken the markers cannot be 
read by the sensors 97, 98. FIG. 16 shows a control system for the printer 
of the invention controlled by a CPU 100. First markers from the ink 
ribbon 94 are read by the sensors 97, 98 and data indicative thereof is 
transmitted to the CPU 100. Then the CPU sends signals to motor control 
circuits 101, 102 for controlling motor 84, associated with the gears 85, 
83, 82, and 81 for driving the take-up reel support projection 69 and 
motor 58 for controlling a position of a supply reel mount 52 for driving 
the supply reel 93 of the ink ribbon cartridge 90, respectively, for 
driving the motors so as to accurately position the ink ribbon 94 for a 
particular operation, such as printing a first color, printing a second 
color, etc. Further, an alarm circuit 103 is provided for signaling 
failure of operation due to breaking of the ink ribbon, jamming, or 
finishing of the available ink ribbon on the ink ribbon cartridge. 
FIG. 19 shows the construction of a single reel type ink ribbon cartridge 
90 for use with the printer of the invention. As seen in the drawing, the 
ink ribbon cartridge comprises an upper casing 92, a lower casing 91 
including protrudent lower ribbon guide portions 91a. The ink ribbon 94 is 
contained on a supply reel 93 (not shown) disposed between the upper and 
lower casings 92, 91. The supply reel 98 may be spring biased, for 
example, to as to provided backtensioning to an unwound portion of the ink 
ribbon 94. An initial, or end portion of the ink ribbon 94 is attached to 
a pull tab 95 to facilitate chucking of the ink ribbon 94 in the printer. 
1. The pull tab includes a through hole 95a for engaging the claw portion 
18 associated with the take-up reel 17 for enabling winding of the ink 
ribbon 94 around the take-up reel 17. Also provided on the pull tab 95 are 
notches 95c, 95c and a marker 95b. The marker 95b detected, by a sensor 
99, (see FIG. 10) so that an initial winding of the ink ribbon 94 around 
the take-up reel 17 is recognized by the CPU 100. The notches 95c, 95c 
serve for restraining wrinkling of the ink ribbon 94 when being drawn out 
of the ink ribbon cartridge 90. According to the present embodiment, the 
ink ribbon has thereon continuous color regions grouped in repeating 
distinct blocks, such as yellow (Y), magenta (M), cyan (C), yellow (Y), 
magenta (M), . . . for example. FIG. 10 shows a condition in which the ink 
ribbon 94 has been initially extracted from the ink ribbon cartridge 90 
and wound around the body portion 17a of the take-up reel 17 via the 
platen roller 21. 
Referring to FIGS. 5 and 6, when the ink ribbon cartridge 90 is set in the 
semicircular shaded ink ribbon cartridge receptacle 13, retained therein 
by a plate spring member 13c provided at one end of the cartridge 
receptacle 13, a longitudinal projecting portion 96 is projected from the 
rear side of the upper and lower casings 92, 91 along a line at which the 
upper and lower casings 92, 91 meet into a receiving groove 13a of the ink 
ribbon cartridge receptacle 13. As seen in FIG. 5, the longitudinal 
projecting portion 96 is provided with a cut-out portion 96b. Further, the 
receiving groove 13a of the ribbon cartridge receptacle 13 is provided 
with a cut-out portion 13b substantially corresponding to the position of 
the cut-out 96b of the ink ribbon cartridge 90. The cut-out portions 13b 
and 96b are provided for allowing the ink ribbon cartridge 90 to be 
engaged with a lock level 110, as best seen in FIG. 6. The lock lever 110 
has at a center portion thereof a lock 110a for retaining the ink ribbon 
cartridge 90 securely in the ink ribbon cartridge receptacle 13. The lock 
110a is of a tapered configuration. The lock lever 110 is mounted on a 
shaft 111 which is attached to a bracket 112 on the inner face of the 
right side plate 6. The lock lever 110 mounted on the shaft 111 is biased 
by a coil spring 113 in the direction of the arrow in FIG. 6 so as to 
maintain the lock portion 110a always in the cut-out portion 13b of the 
ink ribbon cartridge receptacle 13. According to this arrangement, the ink 
ribbon cartridge receptacle is moved slightly in the direction of the 
arrow of FIG. 6 according to unwinding of the ink ribbon 94 of the ink 
ribbon cartridge 90 for always maintaining secure locking of the ink 
ribbon cartridge 90 when installed in the printer 1. An arm portion 110c 
of the lock lever 110 is projected through the right side plate 6 through 
a cut-out 6b provided the side plate 6. The arm portion 110c is associated 
with a lever (not shown) positioned on the outer side of the right side 
plate 6 for effecting locking of the ink ribbon cartridge 90 in the ink 
ribbon cartridge receptacle 13. 
In addition, in FIG. 1, numeral 186 refers to a guide plate, associated 
with the sheet guide plate 11 for guiding a sheet 10 of printing material 
to the platen roller 21. Also, a fence plate 187, or synthetic resin or 
the like is provided for maintaining an edge on the sheet 10 in contact 
with the platen during winding of the platen in clockwise and 
counterclockwise directions to prevent tearing or wrinkling of the sheet 
10 during printing operation. 
In the above-described embodiment of a color printer according to the 
invention, the supply sheet guide plate 11 is disposed at a paper supply 
side of the printer casing 2 for guiding sheets 10 of the printing 
material to the platen 21. At a right side of the printer casing 2 the 
lock lever 110 for locking an ink ribbon cartridge 90 in the ink ribbon 
cartridge receptacle 13 is arranged. When the lock lever is engaged the 
slider, including the slide plate 64 etc., disposed at a side of the ink 
ribbon cartridge 90 from which the ink ribbon 94 is extracted, slides in 
the upward direction. By this action the pinch roller 51 rotatably 
disposed between the shaft receiving plates 61a, 61a of the oscillating 
plate 61 is urged in the direction of the capstan shaft 50 for making 
touching contact between the pinch roller 51 and the capstan shaft 50, 
thus gripping the pull tab 95 of the ink ribbon 94 therebetween. In this 
condition the ink ribbon guide portions 91a, 91a of the lower casing 91 of 
the ink ribbon cartridge 90 are positioned between the pair of shaft 
support plates 61a, 61a of the oscillating plate 61. Therefore, when 
touching contact is effected between the capstan shaft 50 and the pinch 
roller 51, the ink ribbon cartridge is smoothly positioned for effecting 
extraction of the ink ribbon 94 from the ink ribbon cartridge. 
Then, rotation of the capstan shaft 50 is effected for pulling the pull tab 
95 and urging same in the direction of the platen 21. The pull tab 95 is 
then wound counterclockwise around the platen 21 extracting the ink ribbon 
94 from the ink ribbon cartridge 90 and the pull tab 95 is urged in the 
direction of the take up reel 17. As seen in FIGS. 10 and 11, the edge 80b 
of the ink ribbon guide plate 80 urges the pull tab 95 toward the body 17a 
of the take-up reel 17. The take-up reel is rotated in the 
counterclockwise direction and the claw 18, outwardly biased by the spring 
18a, catches the through hole 95a of the pull tab 95 thus catching the 
pull tab 95 to effect winding of the ink cartridge 94 around the take-up 
reel 17. At this time, the sensor 99 is effective to detect the marker 95b 
provided on the pull tab 95 for establishing a correct initial winding 
position for the ink ribbon 94 relative the thermal head 16 such that 
printing operation may be undertaken according to control by the CPU 100. 
Thus chucking operation for the ink ribbon 94 is greatly simplified 
according to the invention. 
Also, as shown by a broken line in FIG. 10, after the ink ribbon is 
sufficiently wound around the take-up reel 17, the ink ribbon guide plate 
80 is moved in a direction away from the cylindrical body portion 17a of 
the take-up reel so as to separate from contact with the ink ribbon 94 and 
the take-up reel 17. 
Hereinbelow a printing operation of the preferred embodiment of the 
invention will be described with reference to FIGS. 20-25. 
First, as seen in FIG. 20, the ink ribbon 94 is extracted and supplied to 
the take-up reel 17 as already described above. 
Then, as seen in FIG. 21, a sheet 10 of paper, etc., from the supply sheet 
guide plate 11 is supplied through the guide rollers 12a, 12a to be wound 
counterclockwise around the platen roller 21, being interposed between the 
platen roller 21 and a lower pinch roller 45. Then, as shown in FIG. 22, 
as the paper is engaged between the lower pinch roller 45 and the platen 
roller 21 the platen driving mechanism 30 is operative to swing the platen 
roller forward and downward. While the swinging motion of the platen 
roller is being effected the platen roller is rotated to bring an upper 
edge of the sheet 10 around the platen roller to a point at which the 
upper edge contacts the upper pinch roller 45a, in contact with the platen 
roller 21. Thus, the sheet 10 is positioned for printing a first color 
(i.e. yellow Y) concurrently with the movement of the platen roller 
downwardly for contacting the ink ribbon 94 with the thermal head 16, the 
sheet 10 being interposed between the ink ribbon 94 and the platen roller 
21 in the manner illustrated in FIG. 22. The thermal head 16 is then 
energized and printing of the first Y image is effected while the platen 
roller is rotated in a counterclockwise direction, At an end of the 
energization, or printing time of the thermal head 16, the platen roller 
21 has moved the sheet 10 to a position such that a lower edge of the 
sheet 10 contacts the lower pinch roller 45 and printing of the first 
color (Y) is completed. 
After printing operation of the first color (Y) is completed, the platen 
driving mechanism 30 is operative to swing the platen roller 21 away from 
the thermal head 16 and the platen roller 21 is simultaneously rotated 
clockwise for returning the sheet 10 to a position which the upper edge 
thereof again contacts the lower pinch roller 45. Then, the ink ribbon 94 
is, as depicted in FIG. 24 further extracted from the ink ribbon cartridge 
90 to be taken up on the take up reel 17 until the sensors 97, 98 detect 
via markers (not shown) on the ink ribbon 94, that the ink ribbon is in 
position for printing the next color (i.e. magenta M). When the ink ribbon 
has been positioned for printing the next color the above-described steps 
of FIGS. 21-23 are repeated. 
Thus is a full color printed image consisting of overlaid images of yellow 
Y, magenta M and cyan C is to be printed, the operation of FIGS. 21-23 is 
repeated three times, after which a full color image will have been 
printed on the sheet 10. Optionally, a black B overlay may also be 
printed, in which case of course the printing operation must be performed 
four times and an appropriate (four color block type) ink ribbon must be 
utilized. 
Then, as shown in FIG. 24, after printing of the last color for completing 
the printed image, as the platen roller 21 is moved away from the thermal 
head by the upward swinging motion of the platen driving mechanism 30, the 
platen roller is rotated counterclockwise so as to move the sheet 10 
around the platen roller 21 through the upper pinch roller 45a to be 
engaged by a discharge roller 88, in contact with the platen roller 21 to 
be discharged onto the discharge guide plate 14. 
Thus, basically, as shown in the drawings, FIG. 21 represents a paper 
supply mode, FIG. 22 shows a printing mode, FIG. 23 shows a paper retract 
mode and FIG. 25 shows a paper discharge mode of the printer of the 
invention. 
Also, during printing operation, as seen in FIG. 18 for example, should a 
condition arise which causes the ink ribbon 94 to be cut or broken, the 
break in the ink ribbon 94 is detected by the sensors 97, 98. Upon such 
detection by the sensors 97, 98, the motor 84 drives the reel mount 69, 
and thereby the take-up reel 17 in a counterclockwise direction and, the 
motor 53 is activated for driving the supply reel mount 52 is a clockwise 
direction and the respective portions of the severed ink ribbon 94 are 
wound onto the take-up reel 17 or onto the supply reel 93 within the 
ribbon cartridge 90. At this time the take-up reel 17 may be easily 
removed from the printer, as described in detail hereinbefore, and then 
replaced after the broken ink ribbon wound thereon has been removed. Then 
the old ink ribbon cartridge 90 may be easily removed and a new ink ribbon 
cartridge 90 loaded in the ink ribbon cartridge receptacle 13 and normal 
printing operation can be resumed. 
Moreover, in a case where the ink ribbon cartridge 90 and the printer 1 
function normally with no malfunction, until the ink ribbon 94 in the ink 
ribbon cartridge 90 is used up, the exhausted ink ribbon 94 wound on the 
take-up reel 17 may be efficiently rewound back around the supply reel 93 
within the ink ribbon cartridge 90 for easy removal. For accomplishing 
this operation, as seen in FIGS. 10 and 12, the edge portion 80b of the 
ink ribbon guide plate 80 applies pressure to the cylindrical body 17a of 
the take-up reel 17 for applying suitable backtensioning to the ink ribbon 
94 such that the ink ribbon 94 may be suitably rewound into the supply 
reel 93 of the ink ribbon cartridge 90 tightly, without wrinkling 
according to clockwise rotation of the supply reel 93 via the reel mount 
52 by activation of the motor 53. Also, due to the arrangement of the claw 
portion 18, biased by the coil spring 18a mounted in the recess 17b of the 
cylindrical body 17a of the take-up reel 17, at a time just before 
completion of the rewinding operation of the ink ribbon 94, smooth 
separation of the claw portion 18 and the through hole 95a of the pull tab 
95 of the ink ribbon 94 is assured. The pull tab is then easily wound back 
around the platen 21 and between the capstan shaft 50 and the pinch roller 
51. 
Another structural feature of the present invention is the mounting of the 
thermal head between the sub-chassis 15 and the main chassis 3. As 
described hereinbefore, the thermal head 16 is arranged to oppose the 
platen roller 21 such that the platen driving mechanism 30 may drive the 
platen roller in and out of contact with the thermal head 16. Since, 
separation between the thermal head and the platen roller 32 is 
maintained, this arrangement allows the main chassis 3 to act to dissipate 
heat generated by the thermal head 16 during printing operations with high 
heat dissipation characteristics. This makes powered fans, or the like, 
and driving circuits therefore, as employed in conventional printers 
unnecessary. Thus, space is conserved and the printer 1 may be made more 
compact as well as thinner, lighter and easier to transport. Power 
consumption may also be reduced and manufacturing costs become lower. 
Further, reliability of the printer is enhanced by the structure of the 
platen rotating mechanism 20, working in conjunction with the platen 
driving mechanism 30 for operating the platen swingably and rotatably to a 
paper (or other printing material) supply mode, a print mode, a paper 
retract mode, and a discharge mode. Moreover, the platen rotating 
mechanism, the platen driving mechanism 30, the ink ribbon guide plates 
71, 77, the ink ribbon guide rollers 75, 79 etc., assure clean separation 
of the ink ribbon 94 and the sheet 10 between printing of each color block 
and reliable, high quality printing can be achieved. 
As mentioned above, since cooling fans, driving circuits therefore and the 
like are not required in the printer according to the invention, costs are 
reduced. In addition however, even though the overall size of the printer 
is reduced, additional space is available within the printer casing 2 for 
optimizing installation of the thermal head 16, the platen rotating 
mechanism 20, the platen driving mechanism 30, the platen 21 itself, etc. 
Thus quality may be improved even while size and costs are reduced. 
Moreover, the present invention utilized a single reel type cartridge which 
further conserves space and simplifies printer operation. As the 
longitudinal projecting portion 96 is provided with the cut-out portion 
96b for engaging the lock lever 110 of the ink ribbon cartridge receptacle 
90, the ink ribbon cartridge may be secured in operating position easily 
by an extremely simple mechanism. Also, according to the structure of the 
invention, the ribbon extracting means, that is, the capstan shaft 50 and 
the pinch roller 51, also serve to help assure correct positioning of the 
the ink ribbon cartridge 90, so space may be conserved and weight reduced. 
Also, since the sensor 99 surely detects the marker 95b on the pull tab 95 
of the ink ribbon 94, misplacement of the ink ribbon in printing operation 
and malfunction during chucking of the ink ribbon 94 is avoided and 
printer reliability is improved. It will be noted that, although optical 
sensors are utilized in the preferred embodiment of a printer according to 
the invention, magnetic sensors, or other suitable sensing means may 
alternatively be employed. 
Also, while the preferred embodiment of the invention is drawn to a color 
video printer, the invention may be applied to any type of multi-pass 
printer requiring aligned overprinting on a single sheet of printing 
material and requiring a paper supply mode, a printing mode a paper 
retract mode and a paper discharge mode. 
While the present invention has been disclosed in terms of the preferred 
embodiment in order to facilitate better understanding thereof, it should 
be appreciated that the invention can be embodied in various ways without 
departing from the principle of the invention. Therefore, the invention 
should be understood to include all possible embodiments and modification 
to the shown embodiments which can be embodies without departing from the 
principle of the invention as set forth in the appended claims.