Printer with support shoe and media metering therein

An apparatus for accurately guiding a web of light-sensitive recording media into a cylindrical support shoe of a printer includes a metering roller at the inlet side of a stationary support shoe around which a received media web is wrapped. At least one media guide belt is mounted about a set of pulleys to guide media toward a nip between a pressure roller and the metering roller through which the media is driven into the stationary support shoe. The metering roller is mounted to rotate about a predetermined axis, and the pressure roller has one end held in a frame and is spring loaded into the frame and the metering roller. The other end of the pressure roller is also spring loaded into the metering roller and into an adjustment plate which is pivotal about the axis of the metering roller, whereby the pressure roller can be steered so that the axis of the metering roller and the axis of rotation of the pressure roller are made parallel, and so that the nip between the metering roller and the pressure roller can be adjusted to lie in a plane defined by the axis of the metering roller and the axis of rotation of the pressure roller to cause media to run uniformly and predictably when metering into and out of the cylindrical support shoe.

CROSS-REFERENCE TO RELATED APPLICATIONS 
Reference is made to commonly assigned, co-pending U.S. patent applications 
Ser. No. 08/123,838 entitled LEADSCREW COUPLER, filed in the names of 
Jadrich et al. on Sep. 20, 1993 and now U.S. Pat. No. 5,392,662; Ser. No. 
08/123,839 entitled METHOD AND APATUS FOR EXPOSING PHOTOSENSITIVE MEDIA 
WITH MULTIPLE LIGHT SOURCES, filed in the names of Smith et al. on Sep. 
20, 1993; Ser. No. 371,346, entitled PRINTER WITH SUPPORT SHOE AND 
ANTI-BACKUP ROLLER, filed concurrently herewith in the name of Mark E. 
Bridges; and Ser. No. 08/371,241, entitled DIGITAL PRINTER WITH SUPPORT 
SHOE AND TRANSLATABLE MEDIA GUIDE MEMBER THEREIN, filed concurrently 
herewith in the name of Mark E. Bridges. 
BACKGROUND OF THE INVENTION 
1. Technical Field 
The present invention relates generally to film printers utilizing 
digitized signals, and more particularly to photographic printers that 
form a web of media into a cylindrical shape for exposure by a rotating 
light source. 
2. Background Art 
Photographic printing of digitized images is accomplished by modulating the 
intensity of a light beam that forms a writing spot on photosensitive 
media as the beam moves relative to the photosensitive media. One type of 
printer uses an array of light emitting diodes (LED's) positioned on a 
rotor which spins within a media support cylinder. The rotor is axially 
translated through the support cylinder to index the LED array to the next 
image line or lines. The light emitting diodes can be directly modulated 
with relatively simple electronic drive circuitry, and can be employed 
with relatively inexpensive, compact and reliable hardware. 
Commonly assigned, co-pending U.S. patent application Ser. No. 08/123,839, 
filed in the name of Smith et al. on Sep. 20, 1993, discloses a high speed 
printer capable of producing full color images on conventional 
photographic paper using digitized information and employing simple and 
inexpensive light sources. A write head assembly includes a plurality of 
individually addressable mono-color LED's arranged in columns and rows to 
emit a plurality of light beams, projection optics, and support 
electronics. The write head assembly is resident on a rotor which is 
simultaneously rotated about a fixed axis and linearly translated past 
stationary photosensitive recording media mounted on the inner surface of 
a cylindrical "support shoe" to form a plurality of writing spots moving 
across the photosensitive material in a fast scan direction and in a slow 
scan direction. The disclosure of the Smith et al. patent is hereby 
specifically incorporated herein by reference. 
When using a printer as disclosed in said U.S. patent application Ser. No. 
08/123,839, the photosensitive recording media must be advanced into the 
support shoe without scratching, and accurately positioned relative to the 
exposure source while the rotating exposure source traverses the axial 
length of the cylindrical support shoe. Numerous methods have evolved for 
manipulating the media relative to the cylindrically formed support shoe 
during the printing operation. 
In U.S. Pat. No. 2,511,892, which issued to Wise on Jun. 20, 1950, the end 
of a roll is fed through a single-turn drive roller pair. The media is 
driven between a pair of mandrels and a flexible sheet. The flexible sheet 
opens and closes about the mandrels, sandwiching the media to the 
mandrels. 
U.S. Pat. No. 3,958,250, which issued to Rolon on May 18, 1976, discloses a 
printer in which the end of a roll of film is driven into a curved 
entrance guide shoe. The shoe diverts the film along a curved wall housed 
within an exposure compartment. 
U.S. Pat. No. 4,479,148, which issued to Sheck et al. on Oct. 23, 1984, 
teaches the use of a transport upon which is taped a flap which retains an 
exposure or reading medium in sheet form for newspaper printing apparatus. 
The transport is urged into registration with rotatable mandrels by means 
of drive rollers. As the mandrels rotate, the transport fills a gap 
between the mandrels and a curved wall until the transport is cylindrical 
in form. The media sheets are loaded by hand, necessitating a dark 
environment for photographic use. 
U.S. Pat. No. 4,686,541, which issued to Rosier on Aug. 11, 1987, discloses 
extracting film from a reel with a first set of drive rollers, guiding the 
film along its edge into a cylindrical support, cutting it, holding the 
film to a cylindrical cradle with a vacuum, and exposing it. 
In U.S. Pat. No. 4,698,647, which issued to Gerlach on Oct. 6, 1987, the 
end of a roll of film is fed into a pair of foam covered rollers, around 
sheet metal deflector guides, up and around two axially adjustable 
non-rotating mandrels, back through another set of deflector guides and 
out to another set of foam covered rollers. The rotor/hub sandwich is 
translated the axial length of the curved film. A film guide cap helps 
direct the film around the mandrels during the initial loading of film. 
The mandrels reduce the amount of exposable media. Additional film waste 
occurs at the ends near the mandrels because travel of the 
carriage-mounted hub arrangement is limited by the placement and structure 
of the mandrels. Although the guides and hubs are chromed, an unacceptable 
level of scratching will undoubtedly occur during film transport and 
carriage translation. 
U.S. Pat. No. 4,816,923, filed by Saotome on Mar. 28, 1989, discloses a 
scanning device that uses drive rollers to feed a sheet into a cylindrical 
support. An edge guide at each end of the cylindrical support, spaced to 
allow insertion of the sheet, steers the sheet until it encounters a stop. 
DISCLOSURE OF THE INVENTION 
It is an object of the present invention to provide improved apparatus for 
accurately guiding a web of light sensitive recording media into a 
cylindrical support shoe. 
According to a feature of the present invention, a printer having a 
stationary support shoe with an inlet side, an outlet side, and an 
at-least-partially cylindrical inner surface for receiving a web of light 
sensitive recording media, includes a metering roller at the inlet side of 
the stationary support shoe around which a received media web is wrapped. 
At least one media guide belt is mounted about a set of pulleys to guide 
media toward a nip between a pressure roller and the metering roller 
through which the media is driven into the stationary support shoe. 
According to another feature of the present invention, the metering roller 
is mounted to rotate about a predetermined axis at the inlet side of the 
stationary support shoe and the pressure roller further has one end held 
in a frame. The other end of the pressure roller is pivotal about the axis 
of the metering roller, whereby the pressure roller can be steered so that 
the axis of the metering roller and the axis of rotation of the pressure 
roller are made parallel, and so that a nip formed between the metering 
roller and the pressure roller can be adjusted to lie in a plane defined 
by the axis of the metering roller and the axis of rotation of the 
pressure roller, wherein the media leaves the nip essentially tangent to a 
leading edge of the cylindrical inner surface of the support shoe. 
The invention, and its objects and advantages, will become more apparent in 
the below description of the preferred embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION 
The present description will be directed in particular to elements forming 
part of, or cooperating more directly with, apparatus in accordance with 
the present invention. It is to be understood that elements not 
specifically shown or described may take various forms well known to those 
skilled in the art. 
A rotary printing system employing a multi-position lens assembly is 
illustrated in FIG. 1, and includes a rotor 1 coupled to a drive motor, 
not shown, supported by a rotor support member 2 which hangs from a 
carriage assembly 3 which is supported for movement along a pair of guide 
rods 4 and 4'. The rotor is arranged to spin and move axially within a 
cylindrical support shoe 5 which is provided with a sheet of 
photosensitive material on the inner surface 6 thereof. Rotor 1 is 
attached to a linear translation assembly comprising rotor support member 
2, carriage assembly 3, and a lead screw 7 driven by a stepper motor. See 
commonly assigned, co-pending U.S. patent application Ser. No. 08/123,838 
entitled LEADSCREW COUPLER, filed in the names of Jadrich et al. on Sep. 
20, 1993. The rotor is simultaneously rotated by the drive motor in a fast 
scan direction and is translated past the cylindrical support shoe in the 
slow scan direction (axially) by the stepper motor and lead screw 7, 
thereby achieving a raster scan pattern on the photosensitive media held 
within the support shoe. 
An LED printhead assembly 8 is mounted in rotor 1 and comprises a plurality 
of mono-color light sources such as an array of LED's and a projection 
lens assembly. The printhead assembly is located within the body of rotor 
1 with the LED array package positioned so that the LED aperture output 
surface is located in a plane which is perpendicular to the optical axis 
of the projection lens assembly. The projection lens assembly is arranged 
to simultaneously image (focus) all of the LED's in the array onto a 
surface located in close proximity above the outer surface of the rotor, 
and more particularly, onto the inner surface of the photosensitive 
material held by support shoe 5. A single projection optics lens array 
thereby images the plurality of LED's onto the photosensitive material as 
a plurality of individual images which constitute the writing beams that 
expose the image pixels. Additional details of the LED array and the 
generation of pixel control signals can be found in afore-mentioned U.S. 
patent application Ser. No. 08/123,839. 
Paper Loading 
Referring to FIG. 2, a web 24 of media is fed from an anti-backup roller, 
not shown, to a metering mechanism illustrated in detail in FIGS. 2, 3, 
and 4. The anti-backup roller and other web-supply features are further 
described in my commonly assigned, co-pending U.S. patent application Ser. 
No. 08/371,346, entitled PRINTER WITH SUPPORT SHOE AND ANTI-BACKUP ROLLER, 
filed concurrently herewith; the disclosure of which is specifically 
incorporated herein by reference. 
A metering roller 34, with a covering of a material with a high coefficient 
of friction such as urethane, is supported on a metering roller shaft 36 
by bearings 38 and 40. At the end of shaft 36 is a pulley 44 which is 
rotatably driven by a stepper motor 50 which responds to control signals 
from a stepper motor driver circuit, not shown. 
Situated about metering roller 34 is a series of pliable media guide belts 
52 which are rotatably, but not drivenly, mounted to a corresponding set 
of guide belt pulleys 54. Media guide belts 52 also loop around grooves 56 
located on a pressure roller 58, the outer diameter of which has a low 
coefficient of friction coating, such as for example Delrin AF or anodized 
aluminum. Pressure roller 58 urges media 24 into contact with metering 
roller 34. 
Pressure roller 58 is rotatably mounted on a pressure roller shaft 60, one 
end of which has a flat 62 that is pivotally limited by a slot 64 in an 
end cap 66 of cylindrical support shoe 5. Flat end 62 is further captured 
in a slot 68 in an adjustment plate 70. Adjustment plate 70 is rotatably 
arranged about bearing 38 for metering roller shaft 36. Adjustment is made 
by turning a set screw 72 which impinges on a stop 74 located on 
cylindrical support end cap 66. A spring 76 is arranged to bias flat end 
62 against slot 68, to urge pressure roller 58 into metering roller 34, 
and to keep set screw 72 against stop 74. Adjustability is provided so 
that the axes of pressure roller 58 and metering roller 34 can be made 
parallel during assembly. The adjustment and exact constraint of pressure 
roller 58 maintains the nip between metering roller 34 and pressure roller 
58 in an axially parallel condition regardless of forward or backward 
metering direction. Flat 62 and slot 68 interface keeps shaft 60 from 
rotating during metering. 
On the other end of pressure roller shaft 60, a round 80 is loosely 
captured by slot 82 in cylindrical support end cap 84. The round end is 
axially held by a retaining ring 86. A spring 88 is arranged to bias round 
end 80 against a flat edge of slot 82, and to urge pressure roller 58 into 
metering roller 34. 
As shown in FIG. 2, media 24 is fed between metering roller 34 and media 
guide belts 52, causing media 24 to be drawn into the nip between metering 
roller 34 and pressure roller 58. The arrangement of these rollers is such 
that, when media 24 leaves the roller nip, the media is essentially 
tangent to the leading edge of cylindrical support shoe 5. 
Cylindrical Support Shoe 
Cylindrical support shoe 5 is constructed so that numerous intermediate 
walls 92 and an outer wall 94 form individual triangularly-shaped manifold 
chambers A, B, C, D, and E, and non-manifold chambers 98, which contribute 
substantially to the self-rigidity of cylindrical support shoe 5. Two end 
caps (only end cap 66 is shown in FIG. 4) are secured at each end of 
support shoe 5 and have holes 100 opening onto manifold chambers A to E, 
to which are attached means to selectively connect a vacuum source, not 
shown. 
The arcuate inner surface of support shoe 5 has radial slots 102, best seen 
in FIG. 4, which communicate the vacuum distributed by manifold chambers A 
to E to the back side of media 24. The vacuum intimately holds media 24 to 
the arcuate inner surface. 
A second set of media guide belts 112, rotatably supported, but not driven 
by, guide belt pulleys, serve to guide media 24 around cylindrical 
manifold chamber E. A first cutting edge 114 of a knife is attached to 
cylindrical support shoe 5. A second cutting edge 116 is slidably mounted 
to impinge upon first cutting edge 114 to thereby create knife means to 
separate a media sheet from media web 24. 
Carriage Assembly 
A translator base assembly 120 is attached via vibration absorbing mounts, 
not shown, to the framework of the light-tight cabinet 10 and supports 
guide rods 4 and 4'. Two sets of wheels 124 and 124' are rotatably 
attached to a carriage 126 which translates along guide rods 4 and 4' by 
means of lead screw 7 turned by a lead screw motor, not shown. See 
afore-mentioned U.S. patent application Ser. No. 08/123,838 entitled 
LEADSCREW COUPLER. Rotor support member 2 is rigidly attached to carriage 
126, and carries a rotor 132 depicted by the dashed circle upon which is 
mounted the illumination means, not shown. Also attached to rotor support 
member 2 is a media guide member 134 that carries a plurality of rollers 
136 angularly distributed around the periphery of media guide member 134. 
Operation 
A leader of media 24 is urged into a guide way formed by media guide belt 
52 and metering roller 34. A sensor means 158 signals the presence of 
media 24 in it's location and signals metering roller 34 to drive in a 
clockwise direction. This has the effect of drawing media 24 into the nip 
between metering roller 34 and pressure roller 58. A second sensor means 
160 is located downstream of the roller nip and turns off drive signals to 
metering roller 34 when the leading edge of media 24 is present. 
Metering roller 34 is rotated by stepper motor 50 in response to control 
signals which causes media 24 to be driven into the space gap created by 
rollers 136 of media guide member 134 and the cylindrical support surface 
of support shoe 5. 
Operation of support shoe 5 to expose media 24 is fully described in my 
commonly assigned, co-pending U.S. patent application Ser. No. 08/371,241, 
entitled DIGITAL PRINTER WITH SUPPORT SHOE AND TRANSLATABLE MEDIA GUIDE 
MEMBER THEREIN, filed concurrently herewith, the disclosure of which is 
specifically incorporated herein by reference. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.