EP0178882B1

EP0178882B1 - Ink jet apparatus and method of operating the same

Info

Publication number: EP0178882B1
Application number: EP19850307371
Authority: EP
Inventors: Thomas William Deyoung
Original assignee: Ricoh Printing Systems America Inc
Current assignee: Ricoh Printing Systems America Inc
Priority date: 1984-10-15
Filing date: 1985-10-14
Publication date: 1989-08-30
Also published as: EP0178882A1; JPH0431310B2; JPS6195946A; CA1252670A; DE3572623D1

Description

This invention relates to an ink jet wherein the ink employed within the jet is of the phase change type which may be referred to as a hot melt ink.
A phase change or hot melt ink of the type utilized in an ink jet is characteristically solid at room temperature. When heated, the ink will melt to a consistency so as to be jettable. The hot melt ink may be jetted from a variety of apparatus.
When employing ink in a liquid state, the delivery of the ink is, of course, dictated by the liquid state. Typically, the ink is contained within a closed vessel of some sort prior to delivery to the ink jet. When employing hot melt ink, the delivery of ink requires a different approach in order to provide a reliable supply and minimize operator intervention.
From EP-A-109754 is known an ink jet printer employing a hot melt ink.
According to one aspect of the invention, there is provided a method of operating an ink jet comprising the following steps:

delivering ink in a solid state in the apparatus;
advancing a portion of said ink in the solid state to a melting location;
melting the ink at the melting location so as to change the ink from a solid state to a liquid state;
supplying the ink in the liquid state to the ink jet; and
ejecting droplets of ink from the ink jet.

According to another aspect of the invention, there is provided an ink jet apparatus comprising:

a reservoir for ink;
a carrier means for storing ink in the solid state and for advancing a portion of the ink and then introducing it in the solid state into the reservoir;
heating means for melting ink introduced into the reservoir, so as to change that ink from a solid state to a liquid state;
at least one ink jet; and
means for feeding ink in the liquid state from said reservoir to said ink jet or jets.

With at least some embodiments of the invention, one or more of the following may be achieved:

-a holt melt ink delivery system wherein operator handling of the ink is minimized.
-a hot melt ink delivery system wherein the ink may be reliably supplied to the ink jet apparatus.
-a hot melt ink delivery system wherein human intervention and delivery of the ink is minimized.
-a hot melt ink delivery system wherein the delivery of ink is automated.
-a hot melt ink delivery system wherein a substantial quantity of ink may be stored in a state of readiness for use by the ink jet apparatus.

In accordance with one preferred feature of the invention, the ink in the solid state may be advanced in the form of a plurality of solid state members. The members may comprise pellets which may assume a substantially cylindrical shape.
The pellets may be advanced in a variety of ways including a pushing of the pellets on the cylindrical surfaces along the axis of the pellets or rolling the pellets about the axis of the pellets.
In accordance with another important feature of the invention, the pellets may be advanced by falling under the influence of gravity before reaching the melting location.
In accordance with yet another feature of the invention, the pellets may be supported in a carrier while being advanced to the melting location. The pellets may be substantially conformed to the shape of the carrier. For example, where cylindrical pellets are utilized, the shape of the carrier may also be cylindrical.
It is preferred that the carrier comprise a removable cartridge which is adapted to store a plurality of ink pellets.
In certain embodiments of the invention, the cartridge may support the pellets in a substantially horizontal plane. The cartridge in then revolved about its axis with a supporting surface holding the pellets within the cartridge until the pellets are advanced to a location so as to fall through an opening in the supporting surface. The revolving portion of the cartridge may comprise an articulated means having carrier pockets. In the alternative, the cartridge may comprise a wheel having pockets. In each case, the pockets preferably conform to the shape of the pellets.
In another embodiment of the invention, pellets are supported in a cartridge in a vertical plane. At least a portion of the cartridge comprises a wheel which revolves such that pellets stored within pockets within the wheel may be moved to a discharge location. The pellets may then be pushed from the pockets and moved to a melting location.
In a further embodiment of the invention, the pellets may be stacked in a bin. Preferably, the bin is suitably shaped such that at least one wall of the bin contacts each pellet. A gate means is located at the bottom of the bin for discharging a single pellet at a time for the bin as the gate means revolves.
The invention will be better understood from the following description given by way of example and with reference to the accompanying drawings, wherein:

Fig. 1 is a perspective view of an ink jet apparatus of the phase change type adapted to be used in conjunction with embodiments of this invention;
Fig. 2 is an orifice plate illustrating the array of ink jets employed in the apparatus of Fig. 1;
Fig. 3 is a sectional view of one embodiment of the invention which may be utilized in conjunction with the apparatus of Figs. 1 and 2;
Fig. 4 is a view of the apparatus of Fig. 3 taken along line 4-4;
Fig. 5 is a plan view of another embodiment of the invention capable of use in conjunction with the apparatus of Figs. 1 and 2;
Fig. 6 is a sectional view of the apparatus of Fig. 5 taken along line 6-6;
Fig. 7 is a plan view of yet another embodiment of the invention capable of use with the apparatus of Figs. 1 and 2;
Fig. 8 is a sectional view of the apparatus of Fig. 7 taken along line 8-8;
Fig. 9 is a sectional view of yet another embodiment of the invention adapted for use with the apparatus of Figs. 1 and 2;
Fig. 10 is a sectional view of the apparatus of Fig. 9 at a subsequent point in time when a pellet is being discharged from the apparatus shown in Fig. 9; and
Fig. 11 is a perspective view of the gate means on the apparatus shown in Figs. 9 and 10.

Referring to Fig. 1, a demand ink jet apparatus is disclosed comprising a head containing a reservoir 10 for ink which is adapted to be supplied in solid state form at a trough 12. Ink received in the trough 12 is elevated in temperature by means of a heater 14 located at the base of the reservoir 10 so as to permit the ink to be supplied in a liquid state to jets 16 of an imaging head 17 juxtaposed to an ink receiving sheet 18 supported on a platen. Each jet includes a chamber and a droplet ejecting orifice (20). The jets 16 are arranged in an array with the orifices 20 substantially aligned as shown in Fig. 2.
The trough 12 is supplied by ink from a carrier 22. The carrier may take on a variety of figurations so as to reliably deliver individual members or pellets of ink in solid state form with a minimum of human intervention. The nature of the apparatus 22 will now be discussed with reference to various embodiments of the invention described in various figures herein.
Referring to Figs. 3 and 4, the trough 12 is supplied by a turret 100 containing a plurality of circumferentially disposed cylindrical pockets 102. The turret 100 revolves about an axially located pin 104 supported from the frame 106 of the apparatus. In this connection, turret 100 includes a sleeve 108 which slips over the pin 104. The base of the sleeve 108 includes a flange 110 with sprocket teeth 112.
As shown in Fig. 3, the pellets 114 located within the pockets 102 are supported by a horizontally extending plate 116. The plate 116 which is stationary includes an opening 117 which is located just above the trough 12. As shown in Fig. 3, the pellet 114 drawn in phantom is dropping through the opening 117 into the trough 12.
The drive mechanism for the turret 100 includes the sprocket teeth 112 operating in conjunction with the spring loaded drive dog 118 shown in Figs. 3 and 4. As shown in Fig. 4 by arrows 120a and 120b, the head 111 is movable. When the head 10 advances in the direction of arrowhead 120a, the dog 118 is withdrawn and the turret 100 remains in the position shown. However, as the head 111 moves in the direction depicted by arrow 120b, the advancing dog 118 engages the sprocket 112 so as to revolve the turret 100 a few degrees (a locking pawl not shown prevents a reversal of the turret motion). Such a few degrees of revolution will advance the next pocket 102 to the discharge location of the opening 117 so as to allow the next pellet 114 fall into the trough 12. As shown in Fig. 4, the dog 118 pivots about a pin 122. A spring 124 attached to the end of the dog 118 opposite the sprocket 112 allows the dog 118 to move into and out of engagement with the sprocket 112 so as to only advance the turret 100 and not reverse the turret. As shown in Fig. 3, spring 124 is attached to pins 126 and 128 mounted on the head 10 of the dog 118 respectively.
It will be appreciated that the apparatus of Figs. 3 and 4 provide means for advancing the ink in its solid state pellet form to the melting location of the head. Of course, once the pellets reach the head, they are melted and supplied to the ink jets for ejecting droplets on demand from the jets 16. As shown in Fig. 3, the pellets 114 are substantially cylindrical and the pockets 102 within the turret 100 conform to the pellets and are therefore substantially cylindrical. Accordingly, the pellets 114 may fall through the discharge opening 117 and are advanced along the axes of the pellet as they fall under the influence of gravity into the trough 12.
The turret or wheel 100 may be readily removable such that the carrier of the pellets is in effect a removable cartridge. The cartridge may then be preloaded with pellets 114 before mounting on the pin 104. The pellets 114 may be held in place within the cartridge during mounting by a removable sheet-like material such as a thin cardboard member which may be pulled free of the turret 100 between the plate 115 and the portion of the revolving turret 100 which carries the pellets 114. It will also be appreciated that the turret 100 as well as the sleeve 108 the flange 110 may be removed as a unit along with the plate 116.
As shown in Figs. 3 and 4, the carrier or cartridge comprises a wheel or turret 100 which carries the pellets 114 in a substantially horizontal plane. It will now be appreciated that other mechanisms may be utilized.
Referring to Figs. 5 and 6, a revolving carrier, articulated, chain-like carrier 200 is disclosed. The carrier includes a plurality of pockets 202 which receive pellets 114 of substantially cylindrical shape so as to conform with the shape of the pockets 202. The pockets 202 are interconnected by linkages 204 so as to assume an oval configuration as shown in Fig. 5 by virtue of an oval shaped guide 206 along which the pockets 202 slide. As in the case of the embodiments in Figs. 3 and 4, the pellets 114 are supported within the pockets 202 by a substantially horizontally extending member 215 which includes a discharge opening 216 located above the trough 12. As shown in Fig. 6, the pellet 114 is falling through the discharge opening 217 into the trough 12.
In this embodiment of the invention, the revolving, articulated carrier 200 is driven by a gear 218 having recesses 220 which contact the exterior of the pockets 202. The gear 218 also includes a flange 212 forming a sprocket as shown in Fig. 4 which is engaged by a dog 218 of the type shown in Fig. 4. As the head 10 advances, the sprockets on the flange 212 are advanced which in turn advances the recesses 220 so as to drive the revolving, chain-like carrier 200. The dog mechanism 218, posts 226 and 228 and spring 224 are substantially identical to those shown in Figs. 3 and 4. A locking pawl not shown prevents a reversal in the movement of the dog 218.
As shown in Fig. 6, the carrier 200 is covered by a plate 230. Where the carrier 200 takes the form of a removable cartridge, the plate 230 is removable so as to permit the carrier 200 to be loaded with pellets 114. Where the carrier is to be utilized as a cartridge, the entire carrier including the gear 118 may be removed and replaced by another cartridge filled with pellets 114.
In the embodiments of Figs. 3 through 6, pellets 114 revolve in a horizontal plane and the axes of the pellets are vertical. Reference will now be made to the embodiments of Figs. 7 and 8 where the pellets 114 revolve in a vertical plane and the axes of the pellets are horizontal. A revolving turret 300 is again employed. However, in this embodiment, the turret is supported on two rollers 302 and 304 which not only support but also revolve the turret 300. As best shown in Fig. 8, the roller 302 is coupled to a motor 306. As the roller 302 rotates, the roller 302 engages the exterior of the turret 300 so as to cause the turret 300 to revolve about its axis.
The turret 300 include a plurality of cylindrical pockets 312 which receive the pellets 114. In order to push the pellets 114 along their longitudinal axes, a solenoid 314 is provided. When the particular pocket 312 reaches the discharge position so as to be located above the trough 12 as shown in Fig. 8, a solenoid 314 is energized so as to push pellet 114 along its longitudinal axis, whereupon gravity will allow the pellet 114 to fair into the trough 12.
The turret 300 is enclosed within a housing 316. The entire housing 316 as well as the motors 306 and the solenoid 314 may be removable as a cartridge. In the alternative, the solenoid 314 and the motors 306 may remain with the appropriate coupling to the turret 300 so as to permit the turret 300 as well as the housing 316 to be removed as a cartridge.
Reference will now be made to Figs. 9 through 11 in connection with another embodiment of the invention. As shown in Figs. 9 and 10, the pellets 114 are stacked within a bin 400 having walls 402 with the axes horizontal. The walls 402 are sufficiently closely spaced relative to the diameters of pellets 114 such that one wall 402 is always in contact with at least one pellet 114. In addition, the walls 402 are tapered at 404 into the vertex 406 of the bin where the pellet 114 is received by a gate 408. The gate itself revolves at the base of the bin 400 by virtue of a gear 410 which is engaged by a rack 412 mounted on the head 10. As the head 111 advances into place, the rack 412 will engage the gear 410 and rotate the gear 408 so as to allow the pellet at the vertex of the bin 400 to move to a discharge position as shown in Fig. 10 and fall under the influence of gravity into the trough 12.
Referring to Fig. 11, the configuration of the gate 408 is disclosed. The gate 408 includes a substantially cylindrical member with a recess 416. The gate 408 also includes a shaft 418 coupled to the gear 410. The recess 416 is sufficiently deep so as to receive the pellet 114 and can permit rotation of the gate 408 and discharge of the pellet 114 without interference with the walls of the bin.
As in the other embodiments, the bin-type approach to pellet feeding lends itself to a cartridge. In this connection, the entire bin including the gate 408 may be removable.
It will be appreciated that in each of the embodiments previously described, a plurality of pellets are supported in a carrier which may be a removable cartridge. The pellets are then advanced in the carrier on a sequential basis to a discharge position from where they fall under the influence of gravity and into the trough 12. It will be appreciated that pellets 114 slide as well as roll along the walls of the bin.

Claims

1. A method of operating an ink jet comprising the following steps:

delivering ink in a solid state in the apparatus;

advancing a portion of said ink in the solid state to a melting location;

melting the ink at the melting location so as to change the ink from a solid state to a liquid state;

supplying the ink in the liquid state to the inkjet; and

ejecting droplets of ink from the ink jet.

2. A method according to claim 1, wherein the ink in the solid state comprises a plurality of solid state members.

3. A method according to claim 1, wherein the ink in the solid state comprises a plurality of pellets.

4. A method according to claim 3, wherein each of the pellets includes a surface which is substantially cylindrical.

5. A method according to claim 4, wherein each of the pellets is advanced along its cylindrical surface prior to reaching the melting location.

6. A method according to claim 5, wherein each of the pellets is pushed from one end along its cylindrical surface prior to reaching the melting location.

7. A method according to any preceding claim wherein each of the pellets falls under the influence of gravity before reaching the melting location.

8. A method according to any one of claims 1 to 4, wherein each of the pellets is supported by a carrier while being advanced to the melting location.

9. A method according to claim 8, wherein each of the pellets is conformed at least in part to the shape of the carrier.

10. A method according to claim 9, wherein the shape of the carrier and the shape of the pellets are substantially cylindrical.

11. A method according to claim 4, wherein each of the pellets is rolled on its cylindrical surface before reaching the melting location.

12. An ink jet apparatus comprising:

a reservoir for ink;

a carrier means for storing ink in the solid state and for advancing a portion of said ink and then introducing it in the solid state into the reservoir;

-heating means for melting ink introduced into the reservoir, so as to change that ink from a solid state to a liquid state;

-at least one ink jet; and

-means for feeding ink in the liquid state from said reservoir to said ink jet or jets.

13. An apparatus according to claim 12, wherein said carrier means comprises a removable cartridge.

14. An apparatus according to claim 13, wherein said removable cartridge stores a plurality of ink pellets.