Stencil printer

A stencil printer capable of printing an image on a paper or similar recording medium by causing ink to ooze out via the perforations of a master is disclosed. The printer includes an ink collecting device for collecting the ink from the circumference of an ink drum. The printer therefore maintains the circumference of the ink drum in a desirable condition and thereby reduces the number of waste papers as far as possible so as to reduced a printing cost.

BACKGROUND OF THE INVENTION
 The present invention relates to a printer and more particularly to a
 stencil printer for printing an image on a paper or similar recording
 medium by causing ink to ooze out via perforations formed in a master.
 A digital thermal printer using a stencil is conventional and includes a
 rotatable ink drum. The ink drum is made up of a porous cylindrical base
 and one or more mesh screens wrapped around the base one above the other
 and formed of resin or metal. The stencil has a laminate structure
 consisting of a thermoplastic resin film (generally about 1 .mu.m to 3
 .mu.m thick) and a porous support implemented by Japanese paper fibers or
 synthetic fibers or a mixture thereof. A thermal head selectively
 perforates the film surface of the stencil by heat in accordance with
 image data. After the perforated part of the stencil, i.e., a master has
 been wrapped around the ink drum, ink feeding means arranged in the ink
 drum feeds ink to the inner periphery of the ink drum. Then, a press
 roller or similar pressing means presses a paper against the ink drum. As
 a result, the ink oozes out via the porous portion of the ink drum and the
 perforations of the master, forming an image on the paper.
 In the above conventional stencil printer, after a printing operation using
 a given master, the stencil is perforated in accordance with the next
 document in order to produce a new master. The new master is automatically
 wrapped around the ink drum for effecting the next printing. So long as
 printing is continuously effected with consecutive masters, a sufficient
 amount of ink is held between the base and the mesh screen of the ink drum
 and can be surely fed even to a new master, rendering even the first
 printing attractive.
 On the other hand, assume that a new master is wrapped around the ink drum
 after the printer has been left unused over a long period of time. Then,
 the ink existing between the base and the mesh screen of the ink drum is
 short of water due to evaporation and small in volume. As a result, a
 substantial period of time is necessary for such ink to infiltrate into
 the porous support of the new master and ooze out via the perforations of
 the thermoplastic resin film of the master.
 The above ink short of water is low in viscosity and sticky. Should such
 ink be transferred to a paper via the perforations of the thermoplastic
 resin film, it would blur an image or would be transferred to the rear of
 another paper (so-called offset). Particularly, in a duplex print mode for
 printing images on both sides of a paper, a desirable printing is not
 achievable until the undesirable ink has been fully consumed.
 Consequently, several papers to several tens of papers should be wasted
 before ink capable of forming a desirable image with a new master is fed
 to the ink drum.
 The mesh screen layer is exposed to air and has a great area. The ink
 deposited on the mesh screen layer and the inner periphery of the ink
 drum, among others, noticeably decreases in viscosity when the printer is
 left unused over a long period of time.
 Technologies relating to the present invention are disclosed in, e.g.,
 Japanese Patent Laid-Open Publication Nos. 6-40139, 6-71996, 6-135111,
 7-257005 and 10-95156 as well as in U.S. Pat. No. 5,782,178.
 SUMMARY OF THE INVENTION
 It is therefore an object of the present invention to provide a stencil
 printer capable of reducing the number of waste papers as far as possible
 and thereby reducing the printing cost.
 In accordance with the present invention, a stencil printer for printing an
 image on a paper or similar recording medium by wrapping a perforated
 master around an ink drum, feeding ink to the ink drum, and causing the
 ink to ooze out via the ink drum and includes an ink collecting device for
 collecting the ink deposited on the circumference of the ink drum, and an
 ink storing device for temporarily storing the ink collected by the ink
 collecting device.
 Also, in accordance with the present invention, a stencil printer for
 printing an image on a paper or similar recording medium by wrapping a
 perforated master around an ink drum, feeding ink to the ink drum, and
 causing the ink to ooze out via the ink drum and master includes a timer
 for counting a period of time elapsed since the end of the last printing,
 an ink collecting device for collecting, when the period of time counted
 by the timer is longer than a preselected period of time, the ink from the
 circumference of the ink drum, and an ink storing device for temporarily
 storing the ink collected by the ink collecting device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Preferred embodiments of the stencil printer in accordance with the present
 invention will be described hereinafter.
 First Embodiment
 Referring to FIGS. 1-17, a stencil printer embodying the present invention
 is shown and generally designated by the reference numeral 1. As shown,
 the printer 1 is generally made up of an image reading section 2, a paper
 feeding section 3, a first and a second master making section 4 and 5,
 respectively, a first and a second master discharging section 6 and 7,
 respectively, a paper discharging section 8, a printing section 9, a
 control section 10, and first and second ink collecting means 250 and 270,
 respectively. The ink collecting means 250 and 270 are not shown in FIG. 1
 for the sake of simplicity of illustration.
 The printer 1 includes a casing or body 23. The image reading section 2 is
 arranged in the upper portion of the casing 23 and includes a glass platen
 11 for laying a document thereon, a roller pair 12 and a roller 13 for
 conveying a document, guides 14 and 15 for guiding the document being
 conveyed, a belt 16 for conveying the document along the glass platen 11,
 and a path selector 17 for switching a direction in which the document
 read should be discharged. The image reading section further includes
 mirrors 18 and 19 and a 4 fluorescent lamp 20 for scanning the document, a
 lens 21 for focusing an imagewise reflection from the document, and a CCD
 (Charge Coupled Device) or similar image sensor 22 for processing the
 reflection or document image incident thereto. The image sensor 22 sends
 an image signal to control means 169 (see FIG. 15) included in the control
 section 10.
 The paper feeding section 3 is positioned at the right middle portion of
 the casing 23. The paper feeding section 3 includes a paper tray 24 loaded
 with a stack of papers P, a pick-up roller 25 and separator rollers 26 and
 27 cooperating to feed the papers P one by one, guides 28 and 29 for
 guiding the paper P being fed, a registration roller pair 30 for nipping
 the leading edge of the paper P and then driving it at a preselected
 timing, and guides 31 and 32 for guiding the paper being conveyed by the
 registration roller pair 30.
 The first master making section 4 is positioned above the paper feeding
 section 3 and includes a stencil 33 implemented as a roll 34. A thermal
 head 35 perforates, or cuts, the stencil 33 by heating it. A platen roller
 36 conveys the stencil 33 while pressing it against the thermal head 35
 and constitutes first master making means together with the head 35.
 Cutting means 37 cuts off the perforated part of the stencil 33, i.e., a
 master at a preselected length. Roller pairs 38 and 39 convey the cut
 stencil or master 33 and constitute first master conveying means.
 The roll 34 includes a core 34a rotatably supported by a support member not
 shown. A stepping motor, not shown, causes the platen roller 36 to rotate.
 The cutting means 37 is made up of a movable edge 37a and a stationary
 edge 37b. The movable edge 37a is rotatable or movable up and down
 relative to the stationary edge 37b.
 The second master making section 5 is arranged at the left middle portion
 of the casing 23 and also includes a stencil 40 in the form of a roll 41.
 The roll 41 has its core 41a rotatably supported by a support member not
 shown. A thermal head 42 and a platen roller 43 constitute second master
 making means. A stepping motor, not shown, causes the platen roller 43 to
 rotate. Cutting means 44 is made up of a movable edge 44a and a stationary
 edge 44b. Roller pairs 45 and 46 constitute second master conveying means.
 Disposed above the second master making section 5 are the first master
 discharging section 6 and first ink collecting means 250 (see FIG. 2) for
 collecting ink from the outer periphery of an ink drum 79. The first
 master discharging section 6 mainly consists of an upper and a lower
 discharge member 47 and 48, respectively, a box 49, and a compressor 50.
 The upper discharge member 47 has a drive roller 51, a driven roller 52,
 and an endless belt 53 passed over the two rollers 51 and 52. The drive
 roller 51 is caused to rotate clockwise, as viewed in FIG. 1, causing the
 belt 53 to move in a direction indicated by an arrow in FIG. 1. The lower
 discharge member 48 also has a drive roller 54, a driven roller 55, and an
 endless belt 56 passed over the two rollers 54 and 55. The drive roller 54
 is caused to rotate counterclockwise, as viewed in FIG. 1, causing the
 belt 56 to move in a direction indicated by an arrow in FIG. 1. Moving
 means, not shown, selectively moves the lower discharge member 48 to a
 position shown in FIG. 1 or a position where the circumference of the
 drive roller 54 contacts the outer periphery of the ink drum 79, as will
 be described specifically later. The box 49 is used to store used masters
 and removably mounted to the casing 23. The compressor 50 compresses a
 used master introduced into the box 49 and is moved up and down by
 elevating means not shown.
 As shown in FIGS. 2 and 3, the first ink collecting means 250 includes a
 roller 251 movable into and out of contact with the outer periphery of the
 ink drum 79 for collecting ink. A backup roller 252 held in contact with
 the inner periphery of the ink drum 79 and faces the roller 251. A blade
 253 scrapes off ink from the circumference of the roller 251. Roller
 moving means 255 moves the roller 251 into and out of contact with the
 outer periphery of the ink drum 79. The control means 169 mentioned
 earlier forms a part of the first ink collecting means 250.
 The roller moving means 255 includes a pair of arms 256 supporting opposite
 axial ends of the roller 251. A solenoid 258 causes the arms 256 to rotate
 about a shaft 257. Specifically, each arm 256 is rotatably supported by
 the casing 23 via the shaft 257 at its intermediate portion. One end 256a
 of the arm 256 is generally L-shaped and supports the roller 251 and blade
 253. The blade 253 is formed of rubber or similar elastic material and
 held in contact with the surface of the roller 251. The solenoid 258 has
 its plunger 258a connected to the other end 256b of the arm 256.
 The control means 169 controls the operation of the solenoid 258.
 Specifically, when the control means 169 does not energize the solenoid
 258, the solenoid 258 maintains the roller 251 spaced from the ink drum
 79, as indicated by a dash-and-dots line in FIG. 3. When the control means
 169 energizes the solenoid 258, the solenoid 258 presses the roller 251
 against the ink drum 79, as indicated by a solid line in FIG. 3.
 The roller 251 and backup roller 252 are formed of rubber or similar
 elastic material. A pair of brackets 259 are affixed to a shaft 82, which
 will be described later, and rotatably support opposite ends of the backup
 roller 252. The backup roller 252 is therefore rotated by the ink drum 79
 when the ink drum 79 is in rotation. In FIGS. 2 and 3, only one of the
 arms 256 and only one of the brackets 259 are shown.
 A waste ink box 254 is removably mounted to the casing 23 below the blade
 253. A block 260 is formed of a highly ink-absorptive material and
 disposed in the waste ink box 254 for preventing collected ink from
 dropping when it is discarded. The block 260 is sponge-like and may be
 formed of polyurethane by way of example. A weight sensor 261 responsive
 to the weight of the block 260 is positioned on the bottom of the waste
 ink box 254. When the weight of the block 260 absorbed collected ink
 exceeds a preselected weight, the weight sensor 261 sends a signal to the
 control means 169 for informing it of such an occurrence.
 A compressor 262 is positioned above the waste ink box 254 for causing the
 block 260 to positively absorb ink collected in the waste ink box 254. The
 compressor 262, like the compressor 50, is movable up and down by being
 driven by elevating means not shown.
 The second ink collecting means 270 is positioned below and at the
 right-hand side of another ink drum 80 for collecting ink from the outer
 periphery of the drum 80. The second ink collecting means 270 is
 substantially identical in configuration with the first ink collecting
 means 250 and will not be described specifically in order to avoid
 redundancy. The control means 169 forms a part of the second ink
 collecting means 270 as well.
 The second master discharging section 7 is arranged below and at the
 right-hand side of the second master making section 5, as viewed in FIG.
 1. The second master discharging section 7, like the first master
 discharging section 6, has an upper and a lower discharge member 57 and
 58, respectively, a box 59, and a compressor 60. The discharge members 57
 and 58 are identical in configuration with the discharge members 47 and
 48, respectively. Specifically, the discharge members 57 and 48 are
 respectively made up of a drive roller 61, a driven roller 62 and an
 endless belt 63 and a drive roller 64, a driven roller 65, and an endless
 belt 66. The drive rollers 61 and 64 respectively cause the belts 63 and
 66 to move in directions indicated by arrows in FIG. 1. Moving means, not
 shown, selectively moves the lower discharge member 58 to a position shown
 in FIG. 1 and a position where the circumference of the drive roller 64
 contacts the outer periphery of the ink drum 80. The box 59 is removably
 mounted to the casing 23 while the compressor 60 is movable up and down by
 being driven by elevating means not shown.
 The paper discharging section 8 is positioned between the second master
 making section 5 and the first master discharging section 6. The paper
 discharging section 8 includes peelers 67 and 68, guides 69 and 70, a
 paper conveyor 71, and a tray 72.
 The peeler 67 is PivotTable supported by opposite side walls, not shown, of
 the casing 23 such that its edge is movable toward and away from the outer
 periphery of the ink drum 79. The peeler 67 is used to separate the paper
 or printing P from the outer periphery of the ink drum 79. This is also
 true with the peeler 68 except that the edge of the peeler 68 is movable
 toward and away from the outer periphery of the ink drum 80. The guides 69
 and 70 are supported by the side walls of the casing 23 and respectively
 guide the printings P removed by the peelers 67 and 68. The paper conveyor
 71 is made up of a drive roller 73, a driven roller 74, an endless belt
 75, and a suction fan 76. While the suction fan 76 retains the paper P on
 the belt 75 by suction, the belt 75 is caused to rotate by the driven
 roller 73 for conveying the paper P in a direction indicated by an arrow
 in FIG. 1. The tray 72 for stacking such papers or printings P includes an
 end fence 78 and a pair of side fences 77 movable toward and away from
 each other in the widthwise direction of the papers P (perpendicularly to
 the direction of paper transport). The tray 72 is foldable to be
 accommodated in the casing 23, as desired.
 The printing section 9 is arranged at the center portion of the casing 23
 and generally made up of the first and second ink drums 79 and 80,
 respectively, and drum drive means 81. The ink drum 79 has a shaft 82 at
 its center that plays the role of a main pipe for feeding ink at the same
 time. A porous support plate 83 is positioned on the outer periphery of
 the ink drum 79 as a first master support plate. First ink feeding means
 84 and ink roller moving means 81 (see FIGS. 7 and 9) are arranged in the
 ink drum 79.
 Specifically, as shown in FIG. 4, two flanges 85 symmetrical in the
 right-and-left direction are rotatably mounted on opposite end portions of
 the shaft 82 via bearings that will be described. As shown in FIGS. 5 and
 6, the flanges 85 each has a part of its circumference implemented as a
 flat portion 85a. A hole 85b greater than the contour of the shaft 82 is
 formed in the center of the flange 85. A cam portion 85c similar in
 configuration to the contour of the flange 85 is formed in the inner
 surface of the flange 85.
 As shown in FIG. 7, identical gears 87 and 142 are respectively mounted on
 the flanges 85 radially inward of the cam portions 85c. The flanges 85 are
 rotatably mounted on the shaft 82 via bearings 88 affixed to the gears 87
 and 142 such that their flat portions 85a lie in the same plane. A stage
 86 is affixed to the flat portions 85a by, e.g., screws and has a bent
 portion 86b at one end. Two hook-shaped pieces 86a are affixed to the
 stage 86 at a preselected distance from each other.
 The porous support plate 83 is wrapped around the flanges 85 with opposite
 ends thereof contacting the flanges 85. The support plate 83 is
 implemented by a thin metal sheet formed with a great number of pores
 therein. Two holes 83a are formed in one end portion of the support plate
 83 in positions corresponding to the pieces 86a and are respectively
 engaged with the pieces 86a. The other end of the support plate 83 is held
 between the circumferences of the flanges 85 and the bent portion 86b of
 the stage 86. In this configuration, when a stress tending to increase the
 radius of the support plate 83 acts from the inside of the ink drum 79,
 the support plate 83 is easily displaceable radially away from the
 circumferences of the flanges 85.
 As shown in FIG. 8, a mesh screen 89 is wrapped around the above support
 plate 83 and formed of resin or metal. A thin mount plate 89a and a thin
 movable mount plate 89b are respectively affixed to opposite ends of the
 mesh screen 89, as illustrated. The mount plate 89a is affixed to the
 stage 86 by, e.g., screws while the movable mount plate 89b is movably
 retained by the stage 86 via two tension springs 89c. The mesh screen 89
 is therefore displaceable radially away from the circumferences of the
 flanges 85 like the support plate 83.
 A damper 90 for clamping the leading edge of the stencil or master 33 has
 its one end pivotally supported by the stage 86. A magnet, not shown, is
 fitted on the other or free end of the damper 90 and allows the damper 90
 to magnetically contact the stage 86. When the ink drum 79 is set in the
 casing 23, the damper 90 is opened and closed at a preselected position by
 opening and closing means not shown.
 As shown in FIGS. 7 and 9, the ink feeding means 84 and ink roller moving
 means 91 are disposed in the ink drum 79. The ink feeding means 84
 includes a pair of flat bases 92, a first support member 93, a second
 support member or ink roller support member 94, a first ink roller 95, and
 a doctor roller 96. The ink roller moving means 91 mainly consists of a
 support plate 97, a solenoid 98, and a stop 99. The bases 92 are mounted
 on the shaft 82 at a preselected distance from each other, and each is
 affixed to the shaft 82 by a respective mount member 100.
 The first support member 93 intervenes between the two bases 92. As shown
 in FIG. 10, the first support member 93 has ears 93a and 93b at opposite
 sides thereof. The ears 93a and 93b each is formed with a hole 93b. A hole
 93c is formed in the intermediate portion of the support member 93 for
 receiving a shaft 102. A shaft 101 is passed through the holes 93b and
 allows the support member 93 to rotate thereabout. A tension spring 104 is
 anchored at one end to one of the bases 92 and at the other end to the
 support member 93. The tension spring 104 constantly biases the support
 member 93 in the counterclockwise direction, as viewed in FIG. 9, about
 the shaft 101. The bias of the tension spring 104 is selected to be
 greater than the bias of the tension springs 89c.
 The second support member 94 mainly consists of two side plates 94a
 positioned outside of the bases 92, a reinforcing member 94b connecting
 the side plates 94a, and a locking rod 94c positioned between the side
 plates 94a. The support member 94 is rotatably mounted on a shaft 102 via
 a bearing 94d positioned at the center of the reinforcing member 94b.
 The ink roller 95 is positioned between the side plates 94a and rotatably
 supported by the side plates 94a via a shaft 95a. Drive means, not shown,
 causes the ink roller 95 to rotate in the same direction as the ink drum
 79. Two cam followers 95b are mounted on opposite ends of the shaft 95a
 and respectively held in contact with the cam portions 85c. When the cam
 followers 95b contact protuberances included in the associated cam
 portions 85c, the circumference of the ink roller 95 is moved away from
 the inner periphery of the porous support plate 83. As soon as the cam
 followers 95b leave the above protuberances, the circumference of the ink
 roller 95 protrudes outward from the circumferences of the flanges 85.
 The doctor roller 96 is positioned such that its circumference adjoins the
 circumference of the ink roller 95. The doctor roller 96 is rotatably
 supported by the side plates 94a and caused to rotate in the opposite
 direction to the ink roller 95 by drive means not shown. Ink fed via the
 shaft or main pipe 82 and a feed pipe 120, which will be described later,
 forms a generally wedge-shaped ink well 96a in the vicinity of the
 circumference of the ink roller 95 and that of the doctor roller 96.
 As shown in FIG. 7, a sensor or ink sensing means 170 is positioned above
 the ink well 96a in order to determined the amount of ink existing in the
 ink well 96a. The sensor 170 is affixed to the side plate 94a via an
 affixing member not shown.
 The support plate 97 is mounted on the shaft 82 between the bases 92 by
 mount members, not shown, similar to the mount member 100. The solenoid 98
 and stop 99 and a sensor 152 are mounted on the support plate 97. The stop
 99 has one end 99a implemented as an outwardly bent hook engageable with
 the locking rod 94c. The stop 99 has its bent port ion 99b rotatably
 supported by a shaft 103. An elongate slot 99c is formed in the stop 99
 between the end 99a and the bent portion 99b. The stop 99 is connected to
 the plunger 98a of the solenoid 98 via the slot 99c. Biasing means, not
 shown, constantly biases the stop 99 in the clockwise direction, as viewed
 in FIG. 9, about the shaft 103. The sensor 152 determines the position of
 the ink roller 95 in terms of the position of the locking rod 94c and is
 implemented by a microswitch.
 The ink drum 80 is positioned below the ink drum 79. A shaft or main pipe
 105 is positioned at the center within the ink drum 80. A porous support
 plate or second master support plate 106 is wrapped around the ink drum
 80. Second ink feeding means 107 and ink roller moving means 108 are
 arranged in the ink drum 80. The ink drum 80 is positioned such that the
 circumference of the porous support plate 106 is spaced from the
 circumference of the porous support plate 83 by a preselected gap of about
 2 mm to 3 mm.
 Flanges 109 and 110 substantially identical with the flanges 85 are
 rotatably mounted on opposite end portions of the shaft 105 via bearings
 and are substantially symmetrical in the right-and-left direction. The
 flanges 109 and 110, like the flanges 85, have flat portions, not shown,
 and cam portions 109b and 110b, respectively. The difference is that, as
 shown in FIG. 7, the flanges 109 and 110 include bosses 109a and 110a,
 respectively. Identical gears 111 and 143 are mounted on the bosses 109a
 and 110a, respectively. The flange 109 is rotatably mounted on the shaft
 105 via a bearing 112 affixed to the gear 111. The flange 110 is rotatably
 mounted on the shaft 105 via a bearing 112 affixed to the gear 143 and a
 bearing 113 affixed to the flange 110.
 The flanges 109 and 110, like the flanges 85, are positioned on the shaft
 105 such that their flat portions lie in the same plane. A stage, not
 shown, is mounted on the flat portions of the flanges 109 and 110 and
 includes hook-like pieces, not shown, and a damper 114. The porous support
 plate 106 and a mesh screen, not shown, are wrapped around the flanges 109
 and 110 in such a manner as to be displaceable radially outward of the
 circumferences of the flanges 109 and 110.
 The ink feeding means 107 and ink roller moving means 108 are disposed in
 the ink drum 80. The ink feeding means 107 includes a base 115, an ink
 roller support member 116, a second ink roller 117, and a doctor roller
 118. The ink roller moving means 108 includes a support member 119, a
 solenoid 120, and a stop 121.
 As shown in FIG. 11, the base 15 has opposite side walls 115a each of which
 is formed with a generally U-shaped notch 115b for receiving the shaft
 105. A rod 115c connects the front portions of the two side walls 115a for
 reinforcement. A notch 115d is formed in the intermediate portion of the
 front end of the base 115. The base 115 is fixed in place by mount members
 similar to the mount members 100 with the notches 115b receiving the shaft
 105.
 The ink roller support member 116 includes two side plates 116a positioned
 outside of the opposite side walls 115a of the base 115, a tie rod 116b
 connecting the side plates 116a, and a locking rod 116c positioned between
 the side plates 116a. The support member 116 is angularly movably mounted
 on the base 115 via a shaft 122. A tension spring 123 is anchored at one
 end to the base 115 and at the other end to the support member 116. The
 tension spring 123 constantly biases the support member 116 in the
 clockwise direction, as viewed in FIG. 9, about the shaft 122. The bias of
 the tension spring 123 is selected to be greater than the bias of the
 tension springs 104.
 The ink roller 117 is positioned between the side plates 116a and rotatably
 supported by the side plates 116a via a shaft 117a. Drive means, not
 shown, causes the ink roller 117 to rotate in the same direction as the
 ink drum 80. Two cam followers 117b are mounted on opposite ends of the
 shaft 117a and respectively held in contact with the cam portions 109b and
 110b. When the cam followers 117b contact protuberances included in the
 associated cam portions 109b and 110b, the circumference of the ink roller
 117 is moved away from the inner periphery of the porous support plate
 106. As soon as the cam followers 117b leave the above protuberances, the
 circumference of the ink roller 117 protrudes outward from the
 circumferences of the flanges 109 and 110.
 The doctor roller 118 is positioned such that its circumference adjoins the
 circumference of the ink roller 117. The doctor roller 118 is rotatably
 supported by the side plates 116a and caused to rotate in the opposite
 direction to the ink roller 117 by drive means not shown. Ink fed via the
 shaft or main pipe 105 and an ink feed pipe 130, which will be described
 later, forms a generally wedge-shaped ink well 118a in the vicinity of the
 circumference of the ink roller 117 and that of the doctor roller 118.
 As shown in FIG. 7, a sensor or ink sensing means 171 is positioned above
 the ink well 118a in order to determined the amount of ink existing in the
 ink well 118a. The sensor 171 is affixed to the side plate 116a via an
 affixing member not shown.
 The support member 119 formed by bending a flat member is affixed to the
 inner periphery of the base 115 by, e.g., screws. The solenoid 120 is
 mounted on the support member 119.
 As shown in FIG. 12, the stop 121 is made up of two legs 121a, a projecting
 portion 121b, a tongue 121c, and a tie rod 121d. The legs 121a are
 rotatably supported by two brackets 124 via a shaft 125. The brackets 124
 are affixed to the base 115. Tension springs 126 are respectively anchored
 to the two legs 121a and two brackets 124. The tension springs 126
 constantly bias the stop 121 in the counterclockwise direction, as viewed
 in FIG. 9, about the shaft 125. The projecting portion 121b connects the
 two legs 121a and projects from the legs 121a. The projecting portion 121b
 is engageable with the locking rod 116c at its stepped portions merging
 into the legs 121a. The tongue 121c protrudes from the projecting portion
 121b and is so positioned as to contact the locking rod 116c when the ink
 roller support member 116 rotates. The tie rod 121d is affixed to
 substantially the centers of the legs 121a at its opposite ends. An
 operating piece 127 is angularly movably supported at one end by a plunger
 120a extending out from the solenoid 120. A pin 127a is studded on the
 other end of the operating piece 127 and engaged with the tie rod 121d.
 The operating piece 127 is angularly movably supported by a shaft 128a
 which is mounted on a mount member 128 affixed to the solenoid 120.
 The feed pipe 129 and a feed pipe 130 are respectively disposed in the ink
 drums 79 and 80 for feeding ink from the shaft or main pipe 82 and a shaft
 or main pipe 105 to the ink well 96a and an ink well 118a. The feed pipes
 129 and 130 each has a single inlet port and four branched outlet ports.
 Feed pumps 265 and 266 (see FIG. 15) are respectively assigned to the ink
 drum 79 and 80 and deliver ink under pressure from an ink pack, not shown,
 to the feed pipes 129 and 130. The ink is fed from the feed pipes 129 and
 130 to the ink wells 96a and 118a, respectively.
 As shown in FIG. 7, the shafts 82 and 105 of the ink drums 79 and 80,
 respectively, each is affixed at one end to a respective positioning
 member 134 mounted on a side wall 133 which forms a part of the casing 23.
 The other end of each of the shafts 82 and 105 is supported by a
 respective mount member 136 via a side wall 135 removably mounted to the
 casing 23. In this configuration, the shafts 82 and 105 are positioned
 relative to the casing 23. Toothed pulleys 137 and 144 are respectively
 rotatably mounted on one end portions of the shafts 82 and 105 outside of
 and integrally with the flanges 85 and 109 via bearings 138. A spacer 139
 is rotatably mounted on the other end portion of the shaft 82 outside of
 and integrally with the flange 85 via a bearing 140, forming a gap between
 the side wall 135 and the flange 85.
 Rotation transmitted to the toothed pulley 137 is applied to a transmission
 member 141 disposed in the ink drum 79. The transmission member 141
 transfers the rotation from one flange 85 to the other flange 85 via the
 gears 87 and 142. The transmission member 141 is made up of a shaft 141a
 rotatably supported by the two bases 92 and gears 141b and 141c mounted on
 opposite ends of the shaft 141a. The gears 141b and 141c are held in mesh
 with the gears 87 and 142, respectively. Rotation transmitted to the other
 toothed pulley 144 is applied to a transmission member 145 disposed in the
 ink drum 80. The transmission member 145 transfers the rotation from one
 flange 109 to the other flange 110 via gears 111 and 143. The transmission
 member 145 is made up of a shaft 145a rotatably supported by the opposite
 side walls 115a and gears 145b and 145c mounted on opposite ends of the
 shaft 145a. The gears 145b and 145c are held in mesh with the gears 111
 and 143, respectively.
 The drum drive means 81 is positioned below and at the right-hand side of
 the ink drum 80. As shown in FIG. 13, the drum drive means 81 includes two
 motors 146 and 147 rotatable in opposite directions to each other. Toothed
 pulleys 148 and 149 are respectively mounted on the output shafts 146a and
 147a of the motors 146 and 147. Timing belts 150 and 151 are respectively
 passed over the toothed pulleys 148 and 137 and the toothed pulleys 149
 and 144. The rotation of the motor and that of the motor 147 are
 respectively transmitted to the ink drums 79 and 80 via the timing belts
 150 and 151, causing them to rotate in opposite directions in synchronism
 with each other.
 An operation panel 153 is positioned at the front portion of the top of the
 casing 23. As shown in FIG. 14 specifically, various conventional keys
 including a perforation start key 154, a print start key 155, a trial
 print key 156, a stop key 157, numeral keys 158, a clear key 159, an
 enlarge (ENL) and a reduce (RED) key 160, a print speed key 161 and a
 continuous print key 162 are arranged on the operation panel 153. Also
 arranged on the operation panel 153 are a display 163 implemented by
 seven-segment LEDs (Light Emitting Diodes) and a display 164 implemented
 by an LCD (Liquid Crystal Display). In the illustrative embodiment, the
 operation panel 153 additionally includes a print mode key 165 and print
 mode display means 166. The print mode key 165 allows the operator to
 select desired one of a duplex print mode for printing images on both
 sides of a paper, a front print mode for printing an image on the front of
 a paper, and a rear print mode for printing an image on the rear of a
 paper. The print mode display means 166 displays the print mode selected
 on the print mode key 165 and is implemented by LEDs. A timer, 267 (see
 FIG. 15) is built in the operation panel 153 for counting a period of time
 elapsed since the end of the last printing operation to the next operation
 of the perforation start key 154.
 The control section 10 disposed in the casing 23 includes the control means
 169 implemented by a conventional microcomputer including a CPU (Central
 Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory),
 etc. The control section 10 controls the operation of the entire printer
 1. The control means 169 serves as a part of the first and second ink
 collecting means 250 and 270 as well, as stated earlier.
 As shown in FIG. 15, the control means 169 receives an image data signal
 output from the image reading section 2, a signal output from the sensor
 152, signals output from the ink sensors 170 and 171, signals output from
 the weight sensors 261 and 281, and control signals output from the
 operation panel 153. In response, the control means 169 controls, based on
 an operation program stored in the above ROM, the paper feeding section 3,
 first and second master making sections 4 and 5, first and second master
 discharging sections 6 and 7, paper discharging section 8, feed pumps 265
 and 266, solenoids 258 and 278, and printing section 9. As for the
 printing section 9, the control means 169 controls the drum drive means 81
 including the motors 146 and 147, ink roller moving means 91 including the
 solenoid 98, and ink roller drive means 108 including the solenoid 120.
 The operation of the printer 1 will be described hereinafter. The operator
 stacks two documents on a document tray, not shown, and then presses the
 perforation start key 154. At this instant, the timer 267 started to
 operate at the end of the last printing operation stops operating and
 sends a signal representative of the period of time which it counted to
 the control means 169. In response, the control means 169 compares the
 period of time with a threshold value stored in the ROM. If the period of
 time counted by the timer exceeds the threshold value, the control means
 169 determines that the printer 1 has been left unused over a long time,
 and calls an operation program assigned to such a condition out of the
 ROM. If the above period of time does not exceed the threshold value, the
 control means 169 calls an operation program assigned to usual printing
 out the ROM.
 A usual print mode will be descried first. The usual print mode includes a
 duplex print mode and a simplex print mode which, in turn, is made up of a
 front print mode and a rear print mode.
 In the duplex print mode, the operator presses the print mode key 165 so as
 to select the duplex print mode and then presses the perforation start key
 154. In response, the motor 146 is energized to rotate the ink drum 79
 counterclockwise. The upper and lower discharge members 47 and 48,
 respectively, cooperate to peel off a used master 167 from the outer
 periphery of the ink drum 79. The used master 167 removed from the ink
 drum 79 is introduced into the box 49 and then compressed by the
 compressor 50. The motor 147 starts rotating at the same time as the ink
 drum 79 and causes the ink drum 80 to rotate clockwise. The upper and
 lower discharge members 57 and 58, respectively, cooperate to peel off a
 used master 168 from the outer periphery of the ink drum 80. The used
 master 168 is introduced into the box 59 and then compressed by the
 compressor 60. The ink drum 79 and 80 each is brought to a stop on
 reaching the respective position for waiting for a master.
 After the discharge of the used masters 167 and 168, the roller pair 12
 included in the image reading section 2 start rotating and feed upper one
 of the two documents to the glass platen 11. While the document is
 conveyed along the glass platen 11, the fluorescent lamp 20 illuminates
 the document. The resulting imagewise reflection from the document is
 reflected by the mirrors 18 and 19 and then focused by the lens 21 on the
 image sensor 22. The image sensor 22 outputs an electric image signal by
 photoelectric conversion. The image signal is input to an
 analog-to-digital (AD) converter, not shown, disposed in the casing 23.
 The document scanned by the image reading section 2 is driven out to a
 tray, not shown, positioned above the belt 16 by the belt 16 and roller
 13.
 The first master making section 4 perforates the stencil 33 in parallel
 with the above document reading operation. Specifically, after the
 discharge of the used masters 167 and 168, the platen roller 36 and roller
 pairs 38 and 39 start rotating in order to pay out the stencil 33 from the
 roll 34. The thermal head 35 perforates the stencil 33 being conveyed.
 That is, a number of heating elements arranged on the head 35 selectively
 generate heat in accordance with a digital image signal routed through the
 AD converter and an image processing section not shown. As a result, a
 thermoplastic resin film forming a part of the stencil 33 is selectively
 perforated by heat.
 Assume that the control means 169 determines, based on the number of steps
 of a stepping motor, not shown, driving the platen roller 36, that the
 leading edge of the stencil 33 has reached a preselected position between
 the stage 86 and the damper 90. Then, the control means 169 sends a signal
 to the opening and closing means in order to close the damper 90 toward
 the stage 86. As a result, the leading edge of the stencil 33 is clamped
 by the stage 86 and damper 90.
 The ink drum 79 is rotated clockwise, as viewed in FIG. 1, at a peripheral
 speed equal to the speed at which the stencil 33 is conveyed, so that the
 stencil 33 is sequentially wrapped around the ink drum 79. When the
 control means 169 determines, again based on the number of steps of the
 stepping motor, that the stencil 33 has been perforated over an area
 corresponding to a single master, it stops the rotation of the platen
 roller 39 and roller pairs 38 and 39. At the same time, the control means
 169 causes the movable edge 37a to rotate and cut off the perforated part
 of the stencil 33, i.e., a master. The master, also labeled 33, is pulled
 out by the rotation of the ink drum 79. When the ink drum 79 again reaches
 its home position, the control means 169 deenergizes the motor 146 and
 thereby positions the ink drum 79.
 Subsequently, the roller pair 12 again starts rotating and conveys the
 other document along the glass platen 11. The document is read in the same
 manner as the previous document and then driven out to the tray. To read a
 single document carrying images on both sides thereof, as distinguished
 from the above two documents, after one side of the document has been
 read, the belt 16 and roller 13 start rotating. At the same time, the path
 selector 17 is angularly moved counterclockwise by a mechanism, not shown,
 so as to steer the document toward the glass platen 11. As a result, the
 other side of the document is read.
 The second master making section 5 operates in the same manner as the first
 master making section 4 in parallel with the operation for reading the
 second document. Specifically, after the discharge of the used master, the
 platen roller 43 and roller pairs 45 and 46 start rotating in order to pay
 out the stencil 40 from the roll 41. The stencil 40 is perforated by the
 thermal head 42 in the same manner as the stencil 33 is perforated by the
 thermal head 35.
 Assume that the control means 169 determines, based on the number of steps
 of a stepping motor, not shown, driving the platen roller 43, that the
 leading edge of the stencil 40 has reached a preselected position. Then,
 the control means 169 sends a signal to the opening and closing means in
 order to close the damper 114 toward the associated stage. As a result,
 the leading edge of the stencil 40 is clamped by the stage and damper 114.
 The ink drum 80 is rotated clockwise, as viewed in FIG. 1, at a peripheral
 speed equal to the speed at which the stencil 40 is conveyed, so that the
 stencil 40 is sequentially wrapped around the ink drum 80. When the
 control means 169 determines, again based on the number of steps of the
 stepping motor, that the stencil 40 has been perforated over an area
 corresponding to a single master, it stops the rotation of the platen
 roller 43 and roller pairs 45 and 46. At the same time, the control means
 169 causes the movable edge 44a to rotate and cut off the perforated part
 of the stencil 40, i.e., a master. The master, also labeled 40, is pulled
 out by the rotation of the ink drum 80. When the ink drum 80 again reaches
 its home position, the control means 169 deenergizes the motor 147 and
 thereby positions the ink drum 80.
 When the masters 33 and 40 have been respectively wrapped around the ink
 drums 79 and 80, the pick-up roller 25 and separator rollers 26 and 27
 rotate while the motors 146 and 147 start operating. As a result, a single
 paper P is fed from the top of the stack loaded on the paper tray 24
 toward the registration roller pair 30, and the ink drums 79 and 80 start
 rotating at a low speed. The registration roller pair 30 nips the leading
 edge of the paper P and then drives it to a position between the ink drums
 79 and 80 at a preselected timing.
 The ink rollers 95 and 117 disposed in the ink drums 79 and 80,
 respectively, are rotated by drive means, not shown, and then caused to
 angularly move in accordance with the rotation of the associated drums 79
 and 80. Specifically, while the solenoid 98 is energized, the ink drum 79
 (flanges 85) is rotated. When the protuberances of the two cam portions
 85c contact the associated cam followers 95b, the ink roller 95 is moved
 upward, as viewed in FIG. 9, forming a clearance between one end 99a of
 the stop 99 and the locking rod 94c. Then, the plunger 98a is pulled into
 the solenoid 98 in order to cause the stop 99 to rotate counterclockwise,
 as viewed in FIG. 9, about the shaft 103. When the cam followers 95b move
 away from the protuberances of the associated cam portions 85c, the first
 and second support members 93 and 94 rotate counterclockwise, as viewed in
 FIG. 9, about the shaft 101 due to the act ion of the tension spring 104.
 Consequently, the circumference of the ink roller 95 contacts the porous
 support plate 83 and causes the support plate 83 and mesh screen 89 to
 bulge out downward, as viewed in FIG. 9. The control means 169 recognizes
 the above movement of the ink roller 95 in response to the output of the
 sensor 152.
 Also, while the solenoid 120 is energized, the ink drum 80 (flanges 109) is
 rotated. When the protuberances of the two cam portions 109b and 110b
 contact the associated cam followers 117b, the ink roller 117 is moved
 downward, as viewed in FIG. 9, forming a clearance between the projecting
 portion 121b of the stop 121 and the A locking rod 116c. Then, the plunger
 120a is pulled into the solenoid 120 in order to cause the stop 121 to
 rotate clockwise, as viewed in FIG. 9, about the shaft 125. When the cam
 followers 117b move away from the protuberances of the associated cam
 portions 109b and 110b, the ink roller support member 116 rotates
 clockwise, as viewed in FIG. 9, about the shaft 122 due to the action of
 the tension spring 123. Consequently, the circumference of the ink roller
 117 contacts the porous support plate 106 and causes the support plate 106
 and mesh screen, not shown, to bulge out upward, as viewed in FIG. 9.
 The registration roller pair 30 feeds the paper P to the position between
 the ink drums 79 and 90 slightly later than the angular movement of the
 ink rollers 95 and 117. As a result, the ink rollers 95 and 117 contact
 each other with the intermediary of the porous support plates 83 and 106,
 mesh screen 89, mesh screen, not shown, masters 33 and 40, and paper P,
 transferring images to both sides of the paper P. At this instant, the
 second support member 94 pivots about the shaft 102, allowing the ink
 roller 95 to evenly contact the ink roller 117 in the axial direction.
 This condition is illustrated in FIGS. 7 and 16.
 The paper with the images, i.e., a printing P is peeled off from the ink
 drum 79 or 80 by the peeler 67 or 68, guided by the guides 69 and 70, and
 conveyed by the paper conveyor 71 to the tray 72.
 The ink drums 79 and 80 are continuously rotated even after the printing
 operation. After the angular movement of the ink rollers 95 and 117, the
 control means 169 deenergizes the solenoids 98 and 120. As a result, the
 stops 99 and 121 are respectively brought to positions where they abut
 against the locking rods 94c and 116c, as indicated by dash-and-dots lines
 in FIG. 16, due to the action of the associated biasing means.
 When the cam followers 95b again contacts the protuberances of the
 associated cam portions 85c due to the rotation of the ink drum 79, the
 first and second support members 93 and 94 rotate clockwise, as viewed in
 FIG. 16, about the shaft 101. As soon as the locking rod 94c and one end
 99a of the stop 99 are released from each other, the stop 99 is caused to
 angularly move by biasing means, not shown, and return to the position
 shown in FIG. 9.
 Likewise, when the cam followers 117b again contact the protuberances of
 the associated cam portions 109b and 110b due to the rotation of the ink
 drum 80, the ink roller support member 116 rotates counterclockwise, as
 viewed in FIG. 16, about the shaft 122. As soon as the locking rod 116c
 and the tongue 121c of the stop 121 are released from each other, the stop
 121 is caused to angularly move by the tension springs 126 and return to
 the position shown in FIG. 9.
 The ink drums 79 and 80 each is brought to a stop on reaching the
 respective home position, completing the master wrapping operation. While
 the printer 1 is held in a stand-by state, the operator presses the trial
 print key 156. In response, the pickup roller 25 and separator rollers 26
 and 27 feed another paper P form the top of the stack on the paper tray
 24. As soon as the registration roller pair 30 nips the leading edge of
 the paper P, the control means 169 energizes the motors 146 and 147 and
 thereby causes the ink drums 79 and 80 to rotate at a high speed. The
 registration roller pair 30 drives the paper P to the position between in
 the ink drums 79 and 80 at the same timing as during master wrapping
 operation. After black images have been transferred to both sides of the
 paper P, the paper or printing P is removed from the ink drum 79 or 80 by
 the peeler 67 or 68. The paper conveyor 71 conveys the paper P to the tray
 72. The drums 79 and 80 are again returned to their home positions and
 stopped there. This is the end of the trial printing operation.
 The operator checks the trial printing P as to the density and position of
 the images and may adjust such factors on the operation panel 153 and
 produce another trial printing. Thereafter, the operator inputs a desired
 number of printings on the numeral keys 158; the number of printings
 appears on the display 163. Subsequently, the operator sets a desired
 printing speed on the print speed key 161 and then presses the print start
 key 155. As a result, papers P are sequentially fed from the paper feeding
 section 3 in order to produce the desired number of printings.
 When the amount of ink in the ink well 96a or 118a decreases during the
 above printing operation, the sensor 170 or 171, respectively, sends a
 signal representative of short ink to the control means 169. In response,
 the control means 169 energizes the feed pump 265 or 266 for replenishing
 fresh ink from the ink pack to the ink well 96a or 118a via the main pipe
 82 or 105 and feed pipe 129 or 130.
 The front print mode belonging to the simplex print mode is as follows. The
 operator selects the front print mode on the print mode key 165, sets a
 single document on the document tray, and then presses the perforation
 start key 154. In response, the first and second master making sections 6
 and 7 each discharges the used master 167 or 168 from the ink drum 79 or
 80 in the same manner as in the duplex print mode. The image reading
 section 2 reads an image out of the document.
 Perforation is executed in parallel with the document reading operation.
 Specifically, the first master making section 4 perforates the stencil 33
 in the same manner as in the duplex print mode. The resulting master 33 is
 wrapped around the ink drum 79. However, the second master making section
 5 does not perforate the stencil 40, so that the resulting master 40 not
 perforated at all is simply wrapped around the ink drum 80.
 After the masters 33 and 40 have been respectively wrapped around the ink
 drums 79 and 80, a single paper P is fed from the paper feeding section 3
 while the ink drums 79 and 80 are caused to rotate at the low speed. The
 registration roller pair 30 drives the paper toward the ink drums 79 and
 80 at the preselected timing stated earlier.
 The ink rollers 95 and 117 are caused to angularly move in accordance with
 the rotation of the ink drums 79 and 80, respectively. The ink rollers 95
 and 117 respectively cause the porous support plates 83 and 106 to bulge
 out and nip the paper P therebetween. In this condition, an image formed
 in the master 33 is transferred to the front or upper surface of the paper
 P because the master 40 is not perforated at all. The paper P carrying the
 image on its front is removed from the ink drum 79 by the peeler 67 and
 then conveyed by the conveyor 71 to the tray 72.
 After the ink drums 79 and 80 have been brought to their home positions and
 stopped there, the operator presses the trial print key 156 in order to
 produce a trial printing. Subsequently, the operator may press the print
 start key 155.
 In the rear print mode also belonging to the simplex print mode, the
 operator selects the rear print mode on the print mode key 165, sets a
 single document on the document tray, and then presses the perforation
 start key 154. In response, the first and second master discharging
 sections 6 and 7 remove the used masters 167 and 168, respectively. On the
 other hand, the image reading section 2 reads an image out of the
 document.
 Perforation is executed in parallel with the document reading operation.
 Specifically, the second master making section 5 perforates the stencil 40
 in the same manner as in the duplex print mode. The resulting master 40 is
 wrapped around the ink drum 80. In this case, the first master making
 section 4 does not perforate the stencil 33, so that the resulting master
 40 not perforated at all is simply wrapped around the ink drum 80.
 After the masters 33 and 40 have been respectively wrapped around the ink
 drums 79 and 80, a single paper P is fed from the paper feeding section 3
 while the ink drums 79 and 80 are caused to rotate at the low speed. The
 registration roller pair 30 drives the paper P toward the ink drums 79 and
 80 at the preselected timing stated earlier.
 The ink rollers 95 and 117 are caused to angularly move in accordance with
 the rotation of the ink drums 79 and 80, respectively. The ink rollers 95
 and 117 respectively cause the porous support plates 83 and 106 to bulge
 out and nip the paper P therebetween. In this condition, an image formed
 in the master 40 is transferred to the rear or lower surface of the paper
 P because the master 33 is not perforated at all. The paper P carrying the
 image on its rear is removed from the ink drum 80 by the peeler 68 and
 then conveyed by the conveyor 71 to the tray 72.
 After the ink drums 79 and 80 have been brought to their home positions and
 stopped there, the operator presses the trial print key 156 in order to
 produce a trial printing. Subsequently, the operator may press the print
 start key 155.
 How the printer 1 operates when the perforation start key 154 is pressed
 after a long time of suspension of the printer 1 will be described
 hereinafter. Generally, the viscosity of ink decreases when the ink is
 left unused over a long period of time. In light of this, after a long
 time of suspension, the ink lowered in viscosity is collected from the
 outer peripheries of the ink drums 79 and 80 in order to reduce the number
 of waste papers ascribable to such undesirable ink. While both the first
 and second ink collecting means 250 and 270 are used for this purpose, the
 following description will concentrate on the operation of the first ink
 collecting means 250 because the two collecting means 250 and 270 are
 identical in operation.
 As shown in FIG. 17, when the operator presses the perforation start key
 154, the control means 169 determines, based on the output of the timer
 267, a period of time elapsed since the end of the last printing
 operation. If the above period of time is longer than a preselected period
 of time (threshold value), then the control means 169 causes an ink
 collect mode operation to start. In the ink collect mode, the used masters
 167 and 168 are respectively removed from the ink drums 79 and 80 as in
 the usual print mode, and the ink drums 70 and 80 are stopped at their
 master waiting positions.
 Subsequently, the ink drums 79 and 80 each is caused to start making a
 preselected number of rotations at the low speed with its outer periphery
 (mesh screen) exposed to the outside. At this instant, the solenoids 98
 and 120 disposed in the ink drums 79 and 80 are not energized. Therefore,
 the locking rods 94c and 116c are respectively stopped by the stops 99 and
 121, maintaining the ink rollers 95 and 117 spaced from the inner
 peripheries of the ink drums 79 and 80, respectively. When the edge of the
 porous portion of the porous support plate 83 arrives at a position where
 it faces the roller 251 of the first ink collecting means 250, the control
 means 169 energizes the solenoid 258 and thereby causes the arms 256 to
 angularly move about the shaft 257. As a result, the roller 251 is moved
 to a position indicated by a solid line in FIG. 3. At this position, the
 roller 251 is pressed against the portion of the outer periphery of the
 ink drum 79 corresponding to the inner periphery of the same which the
 backup roller 252 contacts. When the damper 90 approaches the roller 251,
 the roller 251 is temporarily retracted away from the ink drum 79 to a
 position indicated by a dash-and-dots line in FIG. 3 so as not to contact
 the damper 90.
 In the above condition, the roller 251 and backup roller 252 are
 respectively rotated in directions Al and A2, FIG. 3, in accordance with
 the rotation of the ink drum 79. At the position where the roller 251 and
 backup roller 252 are pressed against each other, the ink lowered in
 viscosity and deposited on the inner periphery of the ink drum 79 is
 forced out to the outer periphery of the drum 79 and transferred to the
 circumference of the roller 251. The blade 253 scrapes off the ink
 deposited on the roller 251. The ink drops from the blade 253 into the
 waste ink box 254 due to its own weight. In FIG. 3, an arrow B indicates
 such transfer of the ink from the ink drum 79 to the waste ink box 254. On
 the elapse of a preselected period of time, the control means 169
 deenergizes the solenoid 258 so as to move the roller 251 away from the
 ink drum 79 to the position indicated by the dash-and-dots line in FIG. 3.
 As stated above, the first and second ink collecting means 250 and 270
 respectively collect the ink lowered in viscosity from the ink drums 79
 and 80 at the above preselected timing. This frees printings from blurring
 and offset during printing and thereby reduces the number of waste papers
 as far as possible so as to reduce the printing cost.
 Even after the collection of the ink, the ink drums 79 and 80 are
 continuously rotated in pressing contact with each other. This
 successfully feeds fresh ink to the ink drums 79 and 80 from which the
 undesirable ink has been collected. Specifically, the control means 169
 energizes the solenoids 98 and 120. As a result, the ink rollers 95 and
 117 being rotated by drive means, not shown, are caused to angularly move
 within the ink drums 79 and 80, respectively.
 The ink rollers 95 and 117 brought into contact with the porous support
 plates 83 and 106, respectively, cause the support plates 83 and 106 to
 bulge out. Consequently, the ink rollers 95 and 117 are pressed against
 each other with the intermediary of the support plates 83 and 106, mesh
 screen 89, and mesh screen not shown. While the ink drums 79 and 80 are
 rotated in the above condition, the control means 169 energize the feed
 pumps 265 and 266 in order to feed fresh ink from the ink pack to the
 inner peripheries of the ink drums 79 and 80 via the ink wells 96a and
 118a, respectively.
 More specifically, when the undesirable ink is collected from the outer
 peripheries of the ink drums 79 and 80, the outer peripheries are short of
 ink. Fresh ink is supplemented to the ink drums 79 and 80 pressed against
 each other in order to make up for the shortage. Therefore, the amount of
 ink to be fed to each of the ink drum 79 and 80 is great enough to fill
 the circumference of the ink drum.
 The ink drums 79 and 80 pressed against each other level the ink left on
 the surface of the mesh screen 89 and that of the mesh screen, not shown,
 due to the perforations of the masters 167 and 168 removed from the ink
 drums 79 and 80. This is successful to substantially uniform the ink
 density on the ink drums 79 and 80. Further, the adequate amount of fresh
 ink fed to the circumferences of the ink drums 79 and 80 fills them, i.e.,
 the mesh screens.
 On completing the predetermined number of rotations, the ink drums 79 and
 80 are brought to a stop at their home positions. Before the stop of
 rotation of the ink drums 79 and 80, the control means 169 deenergizes the
 solenoids 98 and 120. As a result, the stops 99 and 121 return to the
 positions shown in FIG. 9 and retain the ink rollers 95 and 117,
 respectively.
 After the above procedure, the master making operation, master feeding
 operation and printing operation are sequentially executed. At the end of
 the printing operation, the timer 267 again starts counting time. Such a
 sequence of steps are shown in FIG. 17.
 Because the ink density on the ink drums 78 and 80 is substantially uniform
 and because the mesh screens are filled with fresh ink, it is possible to
 start feeding ink smoothly just after the start of a duplex print mode
 operation. In addition, there can be obviated irregularity in density just
 after the start of printing that would increase the number of waste papers
 and therefore the printing cost.
 On the other hand, the ink dropped from the blade 253 into the waste ink
 box 254 infiltrates into the porous block 260. To promote the infiltration
 of the ink into the block 260, the compressor 262 is repeatedly lowered at
 preselected intervals so as to compress the block 260.
 When the ink infiltrates into the block 260 by more than a preselected
 amount, e.g., when the amount of ink absorbed by the block 260
 substantially reaches an allowable limit, the weight sensor 261 responsive
 to the weight of the block 260 sends a signal to the control means 169. In
 response, the control means 169 determines that the block 260 should be
 replaced, and displays a message for urging the operator to replace the
 block 260 on the display 164.
 The operator watching the above message on the display 164 removes the
 waste ink box 254 from the casing 23, discards the block 260, sets a new
 block 260 in the box 254, and again mounts the box 254 to the casing 23.
 Because the ink has infiltrated into and retained by the block 260, the
 block 260 can be easily replaced without the ink dropping or smearing the
 surrounding.
 The weight sensors 261 and 281 are omissible if the time for replacing the
 blocks 260 and 280 is determined on the basis of the number of times of
 ink collection repeated by the ink collecting means 250 and 270. In such a
 case, the number of times of ink collection will be stored in a memory,
 not shown, included in the control means 169, and the message for urging
 the operator to replace the blocks 260 and 280 will be displayed on the
 display 164 when the above number of times coincides with a preselected
 number of times.
 While the illustrative embodiment presses the ink drums 79 and 80 against
 each other after the collection of the ink, the collection of ink may be
 effected at the same time as the pressing of the ink drums 79 and 80.
 Further, in the above embodiment, the control means 169 forms a part of the
 ink collecting means 250 and a part of the ink collecting means 270. If
 desired, an exclusive key, not shown, for ink collection may be added to
 the operation panel 153, so that the operator can cause the ink collecting
 means 250 and 270 to operate without the intermediary of the control means
 169 by pressing the key.
 Second Embodiment
 A second embodiment of the present invention will be described with
 reference to FIGS. 18-22. Because this embodiment is essentially similar
 to the first embodiment, the following description will concentrate only
 on differences. Briefly, this embodiment differs from the first embodiment
 in that it increases, at the time of ink collection, the amounts of ink to
 be fed from the ink wells to the peripheries of the ink drums, temporarily
 stores the I collected ink, and deposits the collected in on used masters.
 As shown in FIG. 18, first ink collecting means 290 is similar to the first
 ink collecting means 250 of the first embodiment and includes a roller or
 ink collecting member 291, a backup roller 292, a blade 293, moving means,
 not shown, for moving the roller 291, and control means 309 (see FIG. 21).
 The ink collected by the blade 293 is temporarily stored in a receptacle
 or ink storing means 294.
 The roller moving means selectively moves the roller 291 to a position
 where it contacts the ink drum 79 (solid line) or a position where it is
 spaced from the ink drum 79 (dash-and-dots line). The backup roller 292
 lightly contacts the inner periphery of the ink drum 79 while facing the
 roller 291. The roller 291, backup roller 292 and blade 293 are formed of
 rubber or similar elastic material.
 The receptacle 294 is positioned below the blade 293 between the first
 master discharging section 6 and the ink drum 79. The receptacle 294
 resembles a box open at its portion facing blade 293.
 A discharge pipe 295 is connected to the bottom of the receptacle 294 for
 depositing the ink collected in the receptacle 294 on the used master 167.
 In this sense, the discharge pipe 295 serves as ink depositing means. As
 shown in FIG. 19, the discharge pipe 295 is configured in the form of a
 letter T and made up of an inlet portion 295a and an outlet portion 295b.
 The outlet portion 295b extends in substantially parallel to the axis of
 the ink drum 79 and is formed with a plurality of holes 295c. The
 dimension of the outlet portion 295b in the axial direction of the ink
 drum 79 is substantially the same as the width of the used master 167.
 A squeeze plate 296 is positioned above the receptacle 294 in order to
 force the ink collected in the receptacle 294 into the discharge pipe 295.
 Squeeze plate drive means 297 (see FIG. 21) moves the squeeze plate 296 up
 and down.
 As shown in FIG. 20, second ink collecting means 300 is positioned between
 the ink drum 80 and the second master discharging section 7 in order to
 collect ink from the outer periphery of the drum 80. The second ink
 collecting means 300 is identical with the first ink collecting means 290
 except for the following. It is to be noted that the control means 309
 forms a part of the second ink collecting means 300 as well.
 The second ink collecting means 300 includes a receptacle 304. A guide
 plate 304a extends out from the edge of the open top of the receptacle 304
 adjoining a blade 303. The guide plate 304a covers the lower portion of
 the blade 303 and guides the ink scraped off by the blade 303 into the
 receptacle 304. A squeeze plate 306 is positioned above the receptacle 304
 and moved up and down by squeeze plate drive means 307 (see FIG. 21).
 An applicator roller pair or ink depositing means 308 is positioned below a
 discharge pipe 305 between the upper and lower discharge members 57 and
 58. The applicator roller pair 308 deposits the collected ink on the used
 master 168.
 As shown in FIGS. 18 and 20, the doctor rollers 96 and 118 are provided
 with ink increasing means 310 and 315, respectively. The ink increasing
 means 310 and 315 respectively increase the amounts of ink to be fed from
 the ink wells 96a and 118a to the circumferences of the ink drums 79 and
 80 at the time of ink collection. Because the ink increasing means 310 and
 315 are substantially identical in configuration, the following
 description wilt concentrate on the ink increasing means 310 by way of
 example. The structural elements of the ink increasing means 315 will be
 simply distinguished from the structural elements of the ink increasing
 means 310 by reference numerals.
 The doctor roller 96 has a shaft 96b supported by a roller arm 311
 angularly movable about a shaft 311a. An arcuate gear portion 312 is
 formed at the top edge of the roller arm 311 and held in mesh with a worm
 gear 314 mounted on the output shaft 313a of a reversible pulse motor 313.
 The pulse motor 313 is connected to the control means 309, FIG. 21. With
 this configuration, it is possible to adjust a so-called doctor gap
 between the ink roller 95 and the doctor roller 96.
 The operation of the illustrative embodiment will be described hereinafter.
 In the usual print mode, the embodiment operates in the same manner as the
 previous embodiment. The following description will therefore concentrate
 on the operation to occur after a long time of suspension of the printer
 1. In the first embodiment, the ink is collected from the circumferences
 of the ink drums 79 and 80. However, even the ink in the ink well 96a and
 118a decrease in viscosity when left unused over a long period of time and
 would bring about waste papers like the ink deposited on the ink drums 79
 and 80. To solve this problem, when the printer 1 is left unused over a
 long period of time, the illustrative embodiment collects the ink not only
 from the circumferences of the ink drums 79 and 80 but also from the ink
 wells 96a and 118a and thereby obviates waste papers more positively.
 First, the collection of ink by the first ink collecting means 290 will be
 described. When the operator presses the perforation start key 154, the
 control means 309 determines, based on the output of the timer 267, how
 long the printer has been left unused since the end of the last printing
 operation. If the period of time counted by the timer is longer than a
 preselected period of time (threshold value), the control means 290 sets
 up an ink collect mode. In the ink collection mode, used masters are
 discharged as in the usual print mode. After the discharge of the used
 masters, the control means 309 rotates the pulse motor 313 in a
 preselected direction and thereby rotates the worm gear 314. The worm gear
 314 causes the roller arm 311 to move about the shaft 311a in a direction
 C1 shown in FIG. 18, increasing a distance D1 between the ink roller 95
 and the doctor roller 96. As a result, the ink layer on the ink roller 95
 increases in thickness and is therefore fed in a greater amount from the
 ink well 96a to the circumference of the ink drum 79.
 Subsequently, the ink drum 79 is caused to start making a preselected
 number of rotations at a low speed. As a result, the ink in the ink well
 96a is transferred to the circumference of the ink drum 79 and then
 collected by the roller 291. The ink collected by the roller 291 is
 temporarily stored in the receptacle 294.
 The operation of the second ink collecting means 300 essentially similar to
 the operation of the first ink collecting means 290 will be briefly
 described. After the discharge of the used master, the control means 309
 drives a pulse motor 318 in a preselected direction and thereby causes a
 roller arm 316 to move about a shaft 316a in a direction C2 shown in FIG.
 20. As a result, a distance D2 between the ink roller 117 and the doctor
 roller 118 and therefore the thickness of the ink layer on the ink roller
 117 increases, increasing the amount of ink to be fed from the ink well
 118a to the circumference of the ink drum 80.
 Thereafter, the ink drum 80 is caused to start making a preselected number
 of rotations at a low speed. As a result, the ink on the ink drum 80 is
 collected by the roller 301 and then scraped off from the roller 301. The
 ink dropped from the roller 301 onto the guide plate 304a is introduced
 into the receptacle 304 along the guide plate 304a and stored therein. At
 the time of collection, the control means 309 energizes the solenoids 98
 and 120 disposed in the ink drums 79 and 80, respectively, so that the ink
 rollers 95 and 117 respectively contact the inner peripheries of the ink
 drums 79 and 80; the ink drums 79 and 80 rotate in pressing contact with
 each other.
 By increasing the distances D1 and D2, as stated above, it is possible to
 rapidly collect even the ink existing in the ink wells 96a and 118a and
 lowered in viscosity due to a long time of suspension, i.e., to collect
 most of such undesirable ink. This renders the printing operation to
 follow desirable.
 After the ink collection performed by the first and second ink collecting
 means 290 and 300, the master making operation, master feeding operation
 and printing operation are sequentially executed. At the time of master
 discharging executed for the next printing operation, the two ink
 depositing means respectively deposit the collected ink on the used
 masters 167 and 168. That is, the ink left in the ink drums 79 and 80
 after the end of printing is collected and temporarily stored and then
 deposited on used masters to be discarded at the time of the next
 printing. The ink is therefore discarded together with the used masters.
 Specifically, the upper and lower discharge members 48 remove the used
 master 167 indicated by a dash-and-dots line in FIG. 18 from the outer
 periphery of the ink drum 79. At this time, the squeeze plate 296 is
 lowered to force out the ink from the receptacle 294 into the discharge
 pipe 295. This ink is routed through the discharge pipe 295 and inlet
 portion 295a to the outlet portion 295b and deposited on the film surface
 (front) of the used master 167 via the holes 295c. The used master 167 is
 conveyed into the box 49 together with the collected ink, compressed by
 the compressor 50, and then discarded.
 On the other hand, the upper and lower discharge members 57 and 58 remove
 the used master 168 indicated by a dash-and-dots line in FIG. 20 from the
 outer circumference of the ink drum 80. When the used master 168 is
 conveyed via the applicator roller pair 308, the squeeze plate 306 is
 lowered to force out the collected ink from the receptacle 304 into the
 discharge pipe 305. This ink flows out via holes, not shown, and deposits
 on the applicator roller pair 308. The applicator roller pair 308 applies
 the ink to the rear of the used master 168. Finally, the used master 168
 carrying the collected ink therewith is introduced into the box 59,
 compressed by the compressor 60, and then discarded.
 It is to be noted that during the discharge of the used masters 167 and
 168, the rollers 291 and 301 are respectively spaced from the ink drums 79
 and 80, as indicated by dash-and-dots lines.
 The applicator roller pair 308 is significant for the following reason. The
 used master 167 being removed from the ink drum 79 is subjected to a
 preselected tension by the cooperative discharge members 47 and 48 and is
 therefore prevented from hanging down despite the deposition of the
 collected ink. However, the deposition of the collected ink on the other
 used master 168 occurs between the discharge members 57 and 58 and the box
 59, so that the used master 168 is apt to hang down due to the collected
 ink. The applicator roller pair 308 is used to apply the collected ink to
 the used master 168 between the discharge members 57 and 58 and the box
 59, thereby preventing the used master 168 from handing down.
 As stated above, when a printing operation is to start with the used
 masters existing on the ink drums 78 and 80 on the elapse of a preselected
 period of time as counted by the timer 267, the ink collecting means 290
 and 300 collect the undesirable ink from the drums 79 and 80,
 respectively. This successfully obviates blurring and offset during
 printing and thereby reduces the number of waste papers as far as possible
 so as to lower the printing cost.
 Moreover, the collected ink is deposited on the used masters 167 and 168
 and discarded together with the used masters 167 and 168. The collected
 ink and used masters 167 and 168 can therefore be discarded by a single
 originally expected step, enhancing efficiency to a significant degree. In
 addition, the illustrative embodiment does not need the porous blocks 260
 and 280 and other disposable members of the previous embodiment and
 further reduces the cost.
 After the above ink collection, the ink drums 79 and 80 are pressed against
 each other such that their circumferences are filled with fresh ink. At
 this instant, the ink increasing means 310 and 315 may be operated in
 order to increase the distances D1 and D2, respectively, so as to increase
 the amounts of ink to be fed to the ink drums 79 and 80. This allows the
 circumferences of the ink drums 79 and 80 to be filled with the fresh ink
 in a short period of time. That is, the fresh ink can fill the mesh
 screens and can be smoothly fed at the time of the next printing
 operation.
 The ink increasing means 310 and 315 are capable of adjusting the distances
 D1 and D2, respectively, in a stepless manner. Alternatively, considering
 the fact that the distances D1 and D2 should only be varied for the usual
 print mode and the ink collect mode, the ink increasing means 310 and 315
 may simply be implemented by, e.g., solenoids.
 In the illustrative embodiment, the ink increasing means 310 and 315 are
 used to feed greater amounts of ink from the ink wells 96a and 118a to the
 ink drums 79 and 80, respectively. Alternatively, if stepless adjustment
 is available for the distances D1 and D2, the means 310 and 315 may be
 used to adjust image density, as taught in Japanese Patent Laid-open
 Publication No. 7-257005.
 In the first and second embodiments, the rollers 251, 271, 291 and 301 for
 ink collection and backup rollers 252, 272, 292 and 302 may be formed of
 metal with or without an elastic material covering the metal.
 If desired, there may be prepared a first ink collection program for
 collecting the ink without operating the ink increasing means 310 and 315
 and a second ink collection program for collecting the ink by operating
 them. In such a case, the two different programs will be selectively used
 in accordance with the period of time elapsed since the end of the last
 printing operation. For example, as shown in FIG. 22, the first program
 and second program may be respectively executed when the above period of
 time is between a first and a second threshold and when it is greater than
 the second threshold.
 While in the illustrated embodiment, the collected ink is deposited on the
 used masters 167 and 168 being removed from the ink drums 79 and 80, it
 may be dropped onto the used masters 167 and 168 respectively discharged
 into the boxes 49 and 59. The crux is that the collected ink be deposited
 on the used masters 167 and 168.
 Third Embodiment
 Reference will be made to FIGS. 23 and 24 for describing a third embodiment
 of the present invention. Because this embodiment is also essentially
 similar to the first embodiment, the following description will
 concentrate on an arrangement unique to this embodiment. Briefly, this
 embodiment is characterized in that it executes the collection, storage
 and deposition of the ink with a single roller.
 As shown in FIG. 23, first ink collecting means 320 is located at a
 position where the upper and lower discharge members 47 and 48 remove the
 used master 167 from the ink drum 79. The ink collecting means 320
 includes a roller or ink collecting member 321, a backup roller 322,
 roller moving means for moving the roller 321 into and out of contact with
 the outer periphery of the ink drum 79, and control means not shown.
 The roller 321 is formed of sponge-like polyurethane or similar highly
 ink-absorptive porous material. The backup roller 322, like the backup
 roller 252, is formed of rubber or similar elastic material and lightly
 contacts the inner periphery of the ink drum 79 while facing the roller
 321. The backup roller 322 is rotatably supported at opposite ends by a
 pair of brackets, not shown, affixed to the shaft 82.
 The roller moving means, like the roller moving means 255, includes a pair
 of pivotable arms rotatably supporting opposite ends of the roller 321,
 and a solenoid causing the arms to angularly move, as needed. The moving
 means moves the roller 321 between a position where the roller 321
 contacts the ink drum 79 (solid line) and a position where it is spaced
 from the ink drum 79 (dash-and-dots line).
 As shown in FIG. 23, second ink collecting means 325 is located at a
 position where the upper and lower discharge members 57 and 58 remove the
 used master 168 from the ink drum 80. The ink collecting means 325
 includes a roller or ink collecting member 326, a backup roller 327,
 roller moving means for moving the roller 326 into and out of contact with
 the outer periphery of the ink drum 80, and the control means. These
 members and means are identical with the members and means of the first
 ink collecting means 320 and will not be described specifically in order
 to avoid redundancy.
 How the roller 321 collects ink will be described first. Assume that the
 perforation start key 154 is pressed after a long time of suspension of
 the printer 1 since the end of the last printing operation. Then, the
 control means, not shown, determines a period of time elapsed since the
 end of the last printing operation on the basis of the output of the timer
 267. If the period of time determined is longer than a preselected period
 of time (threshold value), then the control means sets up an ink collect
 mode. In the ink collect mode, used masters are discharged in the same
 manner as in the usual print mode. After the discharge of the used
 masters, the ink drum 79 is caused to start making a preselected number of
 rotations at a low speed.
 On the rotation of the ink drum 79, the roller 321 is moved from a position
 indicated by a dash-and-dots line in FIG. 23 to a position indicated by a
 solid line. The roller 321 is therefore pressed against the part of the
 outer periphery of the ink drum 49 corresponding to the part of the inner
 periphery which the backup roller 322 contacts. In this condition, as
 shown in FIG. 24A, the roller 321 absorbs ink I deposited on the
 circumference of the ink drum 79 and lowered in viscosity.
 As shown in FIG. 24B, as soon as the ink drum 79 completes the preselected
 number of rotations, the roller 321 is released form the outer periphery
 of the ink drum 79. The ink I has infiltrated into the circumference of
 the roller 321, as indicated by double hatching in FIG. 24B, and is
 temporarily stored in the roller 321.
 After the collection and storage of the ink I by the roller 321, the master
 making operation, master feeding operation and printing operation are
 sequentially executed in the same manner as in the usual print mode. In
 the illustrative embodiment, the operation for causing the ink drums to
 press against each other is omitted. As shown in FIG. 24C, when the master
 discharging operation is executed at the time of the next printing, the
 roller 321 is again pressed against the ink drum 79 with the intermediary
 of the used master 167. As a result, the ink I is squeezed out of the
 roller 321 and transferred to the film surface of the used master 167. The
 used master 167 carrying the ink I therewith is collected in the box 49,
 compressed by the compressor 50, and then discarded.
 As stated above, the rollers 321 and 326 capable of absorbing and retaining
 the ink each plays the role of ink storing means and ink depositing means
 at the same time. The illustrative embodiment therefore renders the device
 for collecting, storing and depositing ink simple and miniature and
 thereby reduces the cost.
 Fourth Embodiment
 Referring to FIGS. 25-31, a fourth embodiment of the present invention will
 be described. This embodiment is essentially similar to the first
 embodiment except that it collects the ink from the inner periphery of
 each ink drum.
 As shown in FIGS. 25 and 26, first ink collecting means 330 for collecting
 the ink from the circumference of the ink drum 79 includes a blade or ink
 collecting member 331. The blade 331 scrapes off the ink deposited on the
 inner periphery of the ink drum 79. A backup roller 332 is positioned to
 face the blade 331 with the intermediary of the circumference of the ink
 79. A suction pump 333 sucks the ink removed by the blade 331. Blade
 moving means 335 moves the blade 331 into and out of contact with the
 inner periphery of the ink drum 79. Roller moving means 336 moves the
 backup roller 332 into and out of contact with the outer periphery of the
 ink drum 79. Control means 329 (see FIG. 31) controls the operation of the
 entire printer 1. A waste ink box or ink storing means 334 is positioned
 outside of the ink drum 79 for storing the ink sucked by the suction pump
 333.
 The blade 331 disposed in the ink drum 79 is pivotable about a shaft 331a
 supported by brackets, not shown, which are affixed to the shaft 82. The
 blade 331 is a flat member formed of rubber or similar elastic material
 and having a length substantially equal to the axial length of the ink
 drum 79.
 An arm 340 is affixed at one end to the shaft 331a and connected at the
 other end to the plunger 341a of a solenoid 341. When the control means
 329 does not energize the solenoid 341, the blade 331 is spaced from the
 inner periphery of the ink drum 79, as indicated by a dash-and-dots line.
 On the energization of the solenoid 341, the blade 331 is pressed against
 the inner periphery of the ink drum 79, as indicated by a solid line. The
 arm 340 and solenoid 341 constitute the blade moving means 335.
 The backup roller 332 is formed of rubber or similar elastic material and
 has a shaft 332a rotatably supported by one end 342a of an arm 342. The
 arm 342 is rotatably supported by the casing 23 via a shaft 343 at its
 substantially intermediate portion. The other end 342b of the arm 342 is
 connected the plunger 344a of a solenoid 344. When the control means 329
 does not energize the solenoid 344, the backup roller 332 is spaced from
 the outer periphery of the ink drum 79, as indicated by a dash-and-dots
 line in FIG. 26. On the energization of the solenoid 344, the backup
 roller 332 is lightly pressed against the outer periphery of the ink drum
 79, as indicated by a solid line in FIG. 26. The arm 342 and solenoid 344
 constitute the roller moving means 336.
 While the blade 331 is pressed against the inner periphery of the ink drum
 79, the ink present on the circumference of the ink drum 79 is collected
 between the blade 331 and the inner periphery of the ink drum 79 in the
 form of a pool 345.
 The shaft 82 has a main pipe 82a (see FIG. 28) therein. A suction pipe 337
 is communicated to the main pipe 82a for sucking the ink from the pool
 345. The suction pump 333 is mounted on the suction pipe 337 for sucking
 the ink from the pool 345. As shown in FIG. 27, the suction pipe 337 has a
 generally T-shaped end portion. To suck the ink from the pool 345
 efficiently, the portion of the suction pipe 337 extending in
 substantially parallel to the axis of the ink drum 79 includes a plurality
 of sucking portions 337a, as illustrated. Each sucking portion 337a is
 formed with a hole 337b for suction at its end.
 As shown in FIG. 28, the suction pipe 337 extends into the shaft 82 and
 terminates at the end portion of the shaft 82 opposite to the end portion
 where the ink inlet port is present. A collection pipe 338 is communicated
 to the suction pipe 337 via a connecting portion 82b formed in the above
 end portion of the shaft 82. As shown in FIG. 29A, the connecting portion
 82b includes a valve 346 for selectively blocking the ink. The valve 346
 is pivotally supported by the shaft 82 via a shaft 346a. A spring 347 is
 mounted on the shaft 346a and constantly biases the valve 346 in the
 closing direction.
 As shown in FIG. 30, the collection pipe 338 is bent at a plurality of
 portions thereof and has an outlet portion 338a positioned above the waste
 ink box 334. The outlet portion 338a has a configuration similar to the
 configuration of the outlet portion 295b of the second embodiment and is
 formed with a plurality of holes 338b.
 The connection of the collection pipe 338 to the suction pipe 337 is as
 follows. When the ink drum 79 is mounted to the printer 1, the collection
 pipe 338 is inserted into the connecting portion 82b until its end abuts
 against the valve 346. As shown in FIG. 29B, when the collection pipe 338
 is inserted deeper into the connecting portion 82b, it causes the valve
 346 to pivot about the shaft 346a and open. As the collection pipe 338 is
 inserted further deeper into the connecting portion 82b, its end abuts
 against the end of the suction pipe 337. As a result, the two pipes 338
 and 338 are fully connected to each other.
 To remove the collection pipe 338, it is released from the connecting
 portion 82b. Consequently, the valve 346 closes due to the action of the
 spring 347 and thereby stops the connecting portion 82b.
 The waste ink box 334 is removably mounted to the casing. A block of highly
 ink-absorptive porous material 339 is disposed in the waste ink box 334
 for preventing the collected ink from dropping when it is discarded. The
 block 339 is sponge-like and may be formed of polyurethane by way of
 example. A weight sensor 349 responsive to the weight of the block 339 is
 positioned on the bottom of the waste ink box 334. When the weight of the
 block 334 absorbed the collected ink exceeds a preselected weight, the
 weight sensor 349 sends a signal to the control means 329 for informing it
 of such an occurrence.
 As shown in FIG. 25, second ink collecting means 350 is associated with the
 ink drum 80. The second ink collecting means 350 is essentially similar to
 the first ink collecting means 330 and will not be described specifically
 in order to avoid redundancy. The structural elements of the second means
 350 identical with the structural elements of the first means 330 are
 simply distinguished by reference numerals. The control means 329 forms a
 part of the second in collecting means 350 as well. As shown in FIG. 31,
 the second ink collecting means 350 includes a blade 351, a backup roller
 352, a solenoid 361 for moving the blade 351, and a solenoid 364 for
 moving the backup roller 352.
 As shown in FIG. 31, the control means 329 controls the various sections of
 the printer 1 in response to the output signals of the various sections
 and various sensors by using the operation programs stored in a ROM.
 The operation of the above embodiment will be described hereinafter.
 Because this embodiment is identical with the first embodiment as to the
 usual print mode operation, the following description will concentrate on
 the operation to occur after a long time of suspension of the printer 1.
 Assume that the operator presses the perforation start key 154 after the
 printer 1 has been left unused over a long period of time. Then, the first
 and second ink collecting means 330 and 350, respectively, are operated to
 collect the ink. Because the two ink collecting means 330 and 350 operate
 in exactly the same manner, only the operation of the first ink collecting
 means 330 will be described by way of example.
 Specifically, when the perforation start key 154 is pressed, the control
 means 329 determines a period of time elapsed since the end of the last
 printing operation on the basis of the output of the timer 267. If the
 period of time elapsed is longer than a preselected period of time
 (threshold value), then the controller 329 sets up the ink collect mode.
 In the ink collect mode, used masters are discharged as in the usual print
 mode. After the discharge of the waste masters, the ink drum 79 is caused
 to start making a preselected number of rotations at a low speed. When the
 edge of the porous part of the porous support plate 83 reaches a position
 where it faces the blade 331, the control means 329 energizes the
 solenoids 341 and 344. As a result, the blade 331 and backup roller 332
 each is moved from the dash-and-dots line position to the solid line
 position shown in FIG. 26, nipping the circumference of the ink drum 79.
 Stated another way, the blade 331 and backup roller 332 are pressed
 against each other via the circumference of the ink drum 79.
 At the position where the blade 331 and backup roller 332 are pressed
 against each other, the ink present on the circumference of the ink drum
 79 and lowered in viscosity is squeezed out to the inner periphery of the
 ink drum 79 by the backup roller 332. The blade 331 scrapes off this ink
 from the inner periphery of the ink drum 79. The ink removed by the blade
 331 forms the pool 345 between the blade 331 and the inner periphery of
 the ink drum 79.
 The control means 329 turns on the suction pump 333 at the same time as it
 energizes the solenoids 341 and 344. The suction pump 333 sucks the ink
 from the pool 345 via the suction pipe 337 and delivers it to the
 collection pipe 338 via the shaft 82. As the pump 333 further sucks the
 ink, the ink in the collection pipe 338 is discharged into the waste ink
 box 334.
 Specifically, the ink drops from the holes 338b of the collection pipe 338
 onto the porous block 339 existing in the waste ink box 334 and
 infiltrates into the block 339. It is noteworthy that the plurality of
 holes 338b allow the ink to efficiently infiltrate into the block 339.
 When the ink drum 79 completes the preselected number of rotations, the
 control means 329 turns off the suction pump 333 and then deenergizes the
 solenoids 341 and 344. Consequently, the blade 331 and backup roller 332
 each returns to the dash-and-dots line position away from the ink drum 79.
 After the collection of the ink, the master making operation, master
 feeding operation and printing operation are sequentially executed in the
 same manner as in the usual print mode. In the illustrative embodiment,
 the operation for collecting the ink and the operation for pressing the
 ink drums 79 and 80 are executed at the same time.
 When the weight of the porous block 339 absorbed the collected ink exceeds
 a preselected amount, e.g., when the amount of ink absorbed by the block
 339 substantially reaches an allowable limit, the weight sensor 349
 responsive to the weight of the block 339 sends a signal to the control
 means 329. In response, the control means 329 determines that the block
 339 should be replaced, and displays a message for urging the operator to
 replace the block 339 on the display 164.
 The operator watching the above message on the display 164 removes the
 waste ink box 334 from the casing 23, discards the block 339, sets a new
 block 339 in the box 334, and then mounts the box 334 to the casing 23.
 Because the ink has infiltrated into and retained by the block 339, the
 block 339 can be easily replaced without the ink dropping or smearing the
 surrounding.
 With the above construction and operation, this embodiment also obviates
 blurring and offset during printing and thereby reduces the number of
 waste papers as far as possible so as to reduce the printing cost.
 In the illustrative embodiment, the backup rollers 332 and 352 are located
 to face the blades 331 and 351, respectively. Alternatively, to omit the
 backup rollers 332 and 352, the blades 331 and 351 may be formed of a
 flexible material so as to collect (scrape off) the ink alone. This is
 because the flexibility of the blades 331 and 351 can replace the pressure
 to be exerted by the backup rollers 332 and 352. When the blades 331 and
 351 collect the ink alone, the ink may be collected at any suitable time
 other than the time for discharging the used masters. For example, the ink
 collection may be automatically effected when the timer 267 counts more
 than a preselected period of time or may be manually effected on an
 exclusive key, not shown, provided on the operation panel 153.
 Fifth Embodiment
 Reference will be made to FIGS. 32-34 for describing a fifth embodiment of
 the present invention. This embodiment is essentially similar to the
 fourth embodiment except that it temporarily stores the collected ink and
 deposits it on the used master. The structural elements of this embodiment
 identical with those of the fourth embodiment will not be described
 specifically in order to avoid redundancy.
 As shown in FIG. 32, first ink collecting means 370 and second ink
 collecting means 380 are associated with the ink drums 79 and 80,
 respectively. Because the first and second ink collecting means 370 and
 380 are essentially similar in construction to each other, the following
 description will concentrate on the first ink collecting means 370 by way
 of example. The structural elements of the second ink collecting means 380
 are simply distinguished from those of the i first ink collecting means
 370 by reference numerals. The operation of the second ink collecting
 means 380 for collecting, storing and applying the ink is identical with
 the operation of the first ink collecting means 380 and will not be
 described specifically.
 As shown in FIG. 32, the first ink collecting means 370, like the first ink
 collecting means of the fourth embodiment, includes a blade or ink
 collecting member 371 for scraping off the ink from the inner periphery of
 the ink drum 79. A backup roller 372 is positioned to face the blade 371
 with the intermediary of the circumference of the ink drum 79. A suction
 pump 373 sucks the ink removed by the blade 371. Blade moving means, not
 shown, moves the blade 371 into and out of contact with the inner
 periphery of the ink drum 79. Roller moving means, not shown, moves the
 backup roller 372 into and out of contact with the outer periphery of the
 ink drum 79. Control means 379 (see FIG. 34) controls the operation of the
 entire printer 1. A box-like receptacle or ink storing means 374 is
 positioned in the vicinity of the ink collecting means 370 for storing the
 ink sucked by the suction pump 373. The control means 379 forms a part of
 the second ink collecting means 380 as well.
 The receptacle 374 is disposed in the ink drum 79 and supported by
 brackets, not shown, affixed to the shaft 82. A suction pipe 375 is
 communicated to the receptacle 374 for transferring the ink collected by
 the blade 371 to the receptacle 374. The suction pump 373 is mounted on
 the suction pipe 375, as illustrated.
 A discharge pipe 376 is also communicated to the receptacle 374 for
 delivering the collected ink to an applicator roller pair 378 which will
 be described later. A discharge pump 377 is mounted on the discharge pipe
 376 for delivering the ink from the receptacle 374 to the applicator
 roller pair 378. The applicator roller pair or ink depositing means 378 is
 positioned between the upper and lower discharge members 47 and 48 for
 depositing the collected ink on the used master 167.
 The discharge pipe 376 is made up of a first pipe 376a and a second pipe
 376b. The first pipe 376a is partly disposed in the shaft 82 and extends
 from the receptacle 374 to the end portion of the shaft 82 remote from the
 end portion where the ink inlet port is present. The second pipe 376b
 extends from the above end portion of the shaft to the applicator roller
 pair 378.
 The shaft 82 has the connecting portion 82b, FIG. 29, where the first and
 second pipes 376a and 376b are connected together. In the illustrative
 embodiment, the first and second pipes 376a and 376b are respectively
 substituted for the suction pipe 337 and collection pipe 338 shown in FIG.
 29.
 The second pipe 376b has an outlet portion, not shown, similar to the
 outlet portion 295b of the pipe 295 of the second embodiment for
 discharging the collected ink. Control means 379 shown in FIG. 34 controls
 the two pumps 373 and 377.
 The operation of the above embodiment will be described hereinafter.
 Because this embodiment is identical with the first embodiment as to the
 usual print mode operation, the following description will concentrate on
 the operation to occur after a long time of suspension of the printer 1.
 Assume that the operator presses the perforation start key 154 after the
 printer 1 has been left unused over a long period of time. Then, the first
 and second ink collecting means 370 and 380, respectively, are operated to
 collect the ink. Because the two ink collecting means 370 and 380 operate
 in exactly the same manner, only the operation of the first ink collecting
 means 370 will be described by way of example. Even the operation of the
 first ink collecting means 370 will be only briefly described because it
 is similar to the operation performed in the fourth embodiment.
 Specifically, when the perforation start key 154 is pressed, the control
 means 379 causes used masters to be discharged and then causes the ink
 drum 79 to start rotating. At this instant, the control means 379 causes
 the blade 371 and backup roller 372 to press themselves against the
 circumference of the ink drum 79. In this condition, the blade 371 scrapes
 off the ink lowered in viscosity from the circumference of the ink drum
 79. The ink removed by the blade 371 is sucked by the suction pump 373 and
 delivered to the receptacle 374 via the suction pipe 375.
 The second ink collecting means 380 collects the ink from the ink drum 80.
 After the collection of the ink by the ink collecting means 370 and 380,
 the master making operation, master feeding operation and printing
 operation are sequentially executed in the same manner as in the usual
 print mode. In the illustrative embodiment, the operation for collecting
 ink and the operation for pressing the ink drums 79 and 80 are effected at
 the same time. At the time of the next discharge of used masters following
 the above procedure, the ink depositing means deposits the collected ink
 on the used master 167.
 Specifically, the cooperative discharge members 47 and 48 peel off the used
 master 167 indicated by a dash-and-dots line in FIG. 32 from the outer
 periphery of the ink drum 79. When the master 167 removed from the ink
 drum 79 is conveyed toward the box 49, the control means 379 turns on the
 discharge pump 377. The discharge pump 377 delivers the collected ink from
 the receptacle 374 to the applicator roller 378 via the first and second
 pipes 376a and 376b.
 As the used masters 167 is conveyed via the applicator roller pair 378, the
 roller pair 378 applies the collected ink to the film surface of the
 master 167. The used master 167 carrying the ink therewith is introduced
 into the box 49, compressed by the compressor 50, and then discarded.
 This embodiment, like the previous embodiments, successfully obviates
 blurring and offset during printing and thereby reduces the number of
 waste papers and therefore the printing cost as far as possible. Further,
 the collected ink is deposited on the used masters 167 and 168 and
 discarded together with the masters 167 and 168, enhancing the efficiency
 of the printer 1. In addition, this embodiment reduces the number of
 disposable members including the porous blocks 260, 280, 339 and 359 and
 therefore the cost, compared to the first and fourth embodiments.
 In the illustrative embodiment, the backup rollers 372 and 382 are also
 located to face the blades 371 and 381, respectively. Alternatively, to
 omit the backup rollers 372 and 382, the blades 371 and 381 may be formed
 of a flexible material so as to collect the ink alone. Again, when the
 blades 371 and 381 collect the ink alone, the ink may be collected at any
 suitable time other than the time for discharging the used masters. For
 example, the ink collection may be automatically effected when the timer
 267 counts more than a preselected period of time or may be manually
 effected on an exclusive key, not shown, provided on the operation panel
 153, as stated earlier.
 Sixth Embodiment
 A sixth embodiment of the present invention will be described with
 reference to FIGS. 35 and 36. This embodiment is essentially similar to
 the fifth embodiment except that it refeeds the collected ink into the
 main pipe and includes unique control means. The following description
 will concentrate on arrangements unique to the sixth embodiment.
 As shown in FIG. 35, a refeed pipe 390 is connected to the receptacle 374
 for refeeding the collected ink to the main pipe 82a of the shaft 82. The
 refeed pipe 390 is partly disposed in the shaft 82 and connected to the
 main pipe 82a within the shaft 82. A refeed pump 391 is mounted on the
 refeed pipe 390 for delivering the collected ink from the receptacle 374
 into the main pipe 82a.
 The refeed pump 391 has the same performance and capacity as the feed pump
 265 and is controlled by control means 392 shown in FIG. 36. The refeed
 pipe 390 and refeed pump 391 constitute ink refeeding means. A refeed pipe
 395 and a refeed pump 396 for refeeding collected ink are also disposed in
 the ink drum 80.
 A temperature sensor or temperature sensing means 393 (see FIG. 36) is
 disposed in the printer 1 for sensing temperature inside the printer 1. As
 shown in FIG. 36, the temperature sensor 393 sends its output
 representative of temperature to the control means 392.
 The operation of the illustrative embodiment will be described hereinafter.
 Because this embodiment is identical with the first embodiment as to the
 usual print mode operation, the following description will concentrate on
 the operation to occur after a long time of suspension of the printer 1,
 i.e., the refeed of the collected ink. The ink collecting operation of
 this embodiment is similar to the operation of the fifth embodiment and
 will not be described specifically. Further, because the operations to
 occur within the ink drums 79 and 80 are identical, only the operation to
 occur in the ink drum 79 will be described.
 After the discharge of used masters, ink is collected from the
 circumference of the ink drum 79 and stored in the receptacle 374. This is
 followed by the master making operation, master feeding operation and
 printing operation as in the usual print mode. In the illustrative
 embodiment, the operation for collecting ink and the operation for
 pressing the ink drums 79 and 80 are effected at the same time. When the
 amount of ink in the ink well 96a decreases during printing, the sensor
 170 sends its output to the control means 392. In response, the control
 means 392 turns on the two pumps 265 and 391.
 The feed pump 265 delivers fresh ink from the ink pack to the ink well 96a
 via the main pipe 82a of the shaft 82. At the same time, the refeed pump
 391 refeeds the collected ink from the receptacle 374 to the main pipe 82a
 via the refeed pipe 390. The fresh ink and collected ink are mixed
 together at the position where the main pipe 82a and refeed pipe 390 join
 each other. The mixed ink is fed to the ink well 96a via the feed pipe
 129. In this manner, the collected ink is fed to the ink well 96a and
 again used for printing. This promotes the efficient use of the ink other
 than the ink discarded together with the used master 167 and reduces ink
 consumption and therefore cost.
 The fresh ink from the ink pack and the collected ink from the receptacle
 374 are mixed together in a particular ration, as follows. Generally, the
 viscosity of ink is dependent on temperature. When temperature is low, the
 viscosity of ink increases and makes it difficult for the ink to penetrate
 the perforations of a master, rendering image density low. When
 temperature is high, the viscosity decreases and allows ink to easily
 penetrate the perforations, rendering image density high. In light of
 this, this embodiment adjusts the mixture ratio of the fresh ink and
 collected ink whose viscosity is low, and thereby adjusts the viscosity of
 the mixed ink.
 Specifically, when ink should be fed to the ink well 96a, the controller
 392 reads temperature represented by the output of the temperature sensor
 393. If temperature inside the printer 1 is medium, e.g., between
 15.degree. C. and 30.degree. C., then the control means 392 mixes the
 fresh ink and collected ink in a ratio of 10:2. Although the resulting
 mixture is slightly lower in viscosity than the fresh ink, such a decrease
 in density does not render image density excessively high or aggravate
 blurring or offset.
 When temperature inside the printer 1 is low, the control means 392
 increases the ratio of the collected ink to the total mixture. For
 example, when temperature inside the printer 1 is lower than 15.degree.
 C., the control means 392 mixes the fresh ink and collected ink in a ratio
 of 10:3. By so increasing the amount of the collected ink, it is possible
 to lower the viscosity of the mixture and prevent image density from
 decreasing.
 When temperature inside the printer 1 is high, the control means 392
 reduces the ratio of the collected ink to the total mixture. For example,
 when temperature inside the printer 1 is higher than 30.degree. C., the
 control means 392 mixes the fresh ink and collected ink in a ratio of
 10:1. By so reducing the amount of the collected ink, it is possible to
 raise the viscosity of the mixture and prevent image density from
 increasing. In addition, the collected ink can be reused.
 When the mixture ratio between the fresh ink and the collected ink is
 adjusted in accordance with temperature, the ink in the ink well can
 maintain substantially constant viscosity without regard to the ambient
 temperature, insuring stable image density at all times.
 In the illustrative embodiment, the backup rollers are also located to face
 the associated blades. Alternatively, to omit the backup rollers, the
 blades may be formed of a flexible material so as to collect the ink
 alone. Again, when the blades collect the ink alone, the ink may be
 collected at any suitable time other than the time for discharging the
 used masters. For example, the ink collection may be automatically
 effected when the timer 267 counts more than a preselected period of time
 or may be manually effected on an exclusive key, not shown, provided on
 the operation panel 153, as stated earlier.
 Seventh Embodiment
 A seventh embodiment of the present invention will be described with
 reference to FIGS. 37-39. This embodiment is essentially similar to the
 fifth embodiment except that it combines the deposition of the collected
 ink on the used master 167 of the fifth embodiment and the refeed of the
 collected ink to the main pipe 82a of the sixth embodiment.
 As shown in FIG. 37, the main pipe 82 of the shaft 82 is connected to the
 connecting port ion 82b. A directional control valve or selector 400 is
 positioned between the connecting portion 82b of the main pipe 82a and the
 feed pipe 129. A first discharge pipe 401 is connected to the valve 400
 and communicated to the receptacle 374. A discharge pump 402 is mounted on
 the first discharge pipe 401 for de delivering the collected ink from the
 receptacle 374 to the valve 400. The second pipe 403 for delivering the
 collected ink to the applicator roller pair 378, as stated in relation to
 the fifth embodiment, is connected to the connecting portion 82b.
 Controller 404 (see FIG. 39) causes the directional control valve 400 to
 selectively feed the collected ink from the receptacle 374 to the main
 pipe 82a or the applicator roller pair 378.
 As shown in FIG. 38, collected ink sensing means 405 is associated with the
 receptacle 374 for determining whether or not the receptacle 374 has been
 filled up with the collected ink. The collected ink sensing means 405
 mainly consists of a float 406 floating on the surface of the collected
 ink, a support arm 408 supporting the float 406 and rotatable about the
 shaft 407, and a photosensor 408 for sensing the end of the support arm
 408a. When the ink collected in the receptacle 374 rises to a preselected
 level and causes the support arm 408 to angularly move, the photosensor
 409 senses the end 408a of the support arm 408 and sends its output to the
 control means 404.
 A first discharge pipe 411, a second discharge pipe 413, a d discharge pump
 412 and collected ink sensing means 415 are also disposed in the ink drum
 80. A directional control valve 410 identical with the valve 400 is
 disposed in the shaft 105.
 As for the usual print mode operation, this embodiment is similar to the
 first embodiment. The following description will concentrate on the
 operation to occur after a long time of suspension. While this embodiment
 first collects ink, the collection of ink will not be described because it
 is identical with the collection of ink executed in the fifth embodiment.
 Further, only the operation to occur within the ink drum 79 will be
 described by way of example.
 After the discharge of used masters, the ink is collected from the
 circumference of the ink drum 79 and stored in the receptacle 374. This is
 followed by the master making operation, master feeding operation and
 printing operation as in the usual print mode. In the illustrative
 embodiment, the operation for collecting the ink and the operation for
 pressing the ink drums 79 and 80 are effected at the same time. When the
 controller 404 determines, based on the output of the sensor 170, that the
 amount of ink in the ink well 96a is short, it operates the directional
 control valve 400 so as to communicate the first discharge pipe 401 to the
 main pipe 82a. Subsequently, the control means 404 turns on the feed pumps
 265 and discharge pump 402.
 The feed pump 265 delivers fresh ink from the ink pack to the ink well 96a
 via the main pipe 82a of the shaft 82. At the same time, the discharge
 pump 402 delivers the collected ink from the receptacle 374 to the main
 pipe 82a via the discharge pipe 401. The fresh ink and collected ink are
 mixed together at the position where the main pipe 82a and discharge pipe
 401 join each other. The mixed ink is fed to the ink well 96a via the feed
 pipe 129. In this manner, the co collected ink is again fed to the ink
 well 96a and used for printing. This promotes the efficient use of the ink
 other than the ink discarded together with the used master 167 and reduces
 ink consumption and therefore cost.
 However when temperature inside the printer 1 is high and the amount of
 collected ink refed to the ink well 96a is short or when the ink
 collection is frequency repeated within a short period of time, the amount
 of ink collected in the receptacle 374 increases. It follows that when the
 ink is collected more than it is refed, the amount of ink in the
 receptacle 374 increases and is apt to fill up the receptacle 374.
 In light of the above, the collected ink sensing means 405 senses the ink
 level in the receptacle 374. If the receptacle 374 is full at the time of
 discharge of used masters, the control means 404 operates the valve 400 so
 as to communicate the first discharge pipe 401 to the second discharge
 pipe 403. Then, the control means 404 turns on the discharge pump 402. The
 discharge pump 402 delivers the collected ink from the receptacle 374 to
 the applicator roller pair 378 via the first and second discharge pipes
 401 and 402. The applicator roller pair 378 deposits the collected ink on
 the used master 167. As a result, the collected ink is discarded together
 with the used master 167.
 As stated above, the illustrative embodiment monitors the amount of ink
 collected in the receptacle 374. When the ink is collected more than it is
 refed and increases the ink level in the receptacle 374, the ink in the
 receptacle 374 is discarded. Therefore, even when the space available in
 the receptacle 374 for the collected ink decreases, the embodiment
 successfully operates and effectively uses the collected ink.
 In the first to seventh embodiments shown and described, both of the ink
 feeding means 84 and 107 are constructed to be movable. Alternatively. an
 arrangement may be made such that one of the two ink feeding means 84 and
 107 is fixed in place with its ink roller adjoining the inner periphery of
 the porous support plate while the other ink feeding means is movable.
 This is also successful to press the porous support plates of the ink
 drums 79 and 80 against each other. In such a case, the movable ink
 feeding means 84 or 107, like the ink feeding means 84, will be allowed to
 angularly move about the shaft 82 or 105.
 Further, the ink collecting means of the present invention achieves the
 above various advantages even when applied to a stencil printer of the
 type moving one ink drum relative to the other or stationary ink drum for
 producing duplex printings, as taught in, e. g., Japanese Patent Laid-Open
 Publication No. 6-71996 or 6-135111 mentioned earlier. Of course, the ink
 collecting means of the present invention is applicable to a stencil
 printer having only a simplex printing capability as distinguished form
 the duplex printing capability shown and described.
 In summary, it will be seen that the present invention provides a stencil
 printer having various unprecedented advantages, as enumerated below.
 (1) Ink collecting means collects ink from the circumference of an ink drum
 and thereby maintains the circumference in a desirable condition.
 (2) When a period of time counted by time counting means exceeds a
 preselected period of time, the ink collecting means collects ink
 deposited on the circumference of the ink drum and lowered in viscosity
 due to a long time of suspension of the printer. This obviates blurring
 and offset during printing and thereby reduces the number of waste papers
 as far as possible so as to reduce the printing cost.
 (3) Ink collected in ink storing means is applied to a used master. The
 collected ink is therefore absorbed by the used master and discarded
 together with the used master, enhancing operation efficiency.
 (4) Ink stored in the ink storing means is refed to an ink well formed in
 the ink drum and again used for printing. This promotes the efficient use
 of ink and reduces ink consumption and therefore cost.
 (5) Ink collected in the ink storing means is selectively refed to the ink
 well or deposited on the used master, depending on the amount of ink
 collected in the ink storing means. The collected ink can therefore be
 reused. Further, the collected ink can be discarded together with the used
 master. In addition, when the ink is collected more than it is reused and
 raises the ink level in the ink storing means, the collected ink is
 discarded in order to guarantee a space in the ink storing means for
 storing the ink.
 (6) The amount of collected ink to be refed to the ink well is adjusted in
 accordance with temperature inside the printer, so that a mixture ratio
 between the collected ink and fresh ink is adequately adjusted. Ink in the
 ink well can therefore maintain substantially constant viscosity without
 regard to the ambient temperature, insuring stable image density at all
 times.
 (7) At the time of ink collection, the amount of ink to be fed from the ink
 well to the circumference of the ink drum is increased. This allows the
 ink in the ink well and lowered in viscosity to be rapidly collected. As a
 result, most of the ink existing in the printer and lowered in viscosity
 is collected, so that desirable printings can be produced thereafter. In
 addition, the number of waste papers and therefore cost can be reduced
 more positively.
 (8) Two ink drums are caused to make a preselected number of rotations in
 pressing contact with each other. This is successful to level the ink left
 on the outer peripheries of the ink drums due to the perforations of used
 masters. As a result, the ink on each drum is uniformed in density and
 fills the outer periphery of the drum. Therefore, the ink can be smoothly
 fed at the beginning of printing in a duplex print mode. In addition,
 there can be obviated irregularity in density just after the beginning of
 printing. Consequently, the number of waste papers and therefore printing
 cost can be reduced.
 (9) Ink can be surely collected at a preselected timing matching with the
 movement of the ink drum.
 (10) A blade is capable of scraping off ink from the periphery of the ink
 drum alone, using its own property. The arrangement is therefore simpler
 and lower in cost than the arrangement using a backup roller in
 combination with a blade for ink collection.
 (11) The ink collecting means playing the role of ink storing means and ink
 depositing means at the same time further simplifies the arrangement and
 reduces the production cost.
 Various modifications will become possible for those skilled in the art
 after receiving the teachings of the present disclosure without departing
 from the scope thereof.