GB2436317A

GB2436317A - Printing apparatus

Info

Publication number: GB2436317A
Application number: GB0605566A
Authority: GB
Inventors: Lain Ansell; Simon Roderick Grover; Nick John Collier; Dominic George Webber
Original assignee: Markem Technologies Ltd
Current assignee: Markem Imaje Industries Ltd
Priority date: 2006-03-20
Filing date: 2006-03-20
Publication date: 2007-09-26
Also published as: GB0605566D0

Abstract

A printing apparatus (10) includes a printing station (11) at which a print head (12) is provided, the print head (12) being moveable in a first direction towards a printing position in which in use the print head (12) is urged towards a substrate on which an image is to be printed to transfer ink from an inked carrier ribbon (14) disposed between the print head (12) and the substrate to the substrate, and a second opposite, rest, position in which in use the print head (12) is spaced away from any substrate to permit substrate to be moved to, through and from the printing station (11), there being a solenoid operated actuator (24) for effecting print head (12) movement under the control of a controller (21), the apparatus (10) further including a storage spool (15) which stores a supply of the inked carrier ribbon (14), a take-up spool (16) for taking up used ribbon, and a ribbon feed path between the storage and take-up spools (15, 16) through the printing station (11), at least the take-up spool (16) being rotatable by a drive motor (56), and wherein the apparatus (10) includes a body member (20), the storage and take-up spools (15, 16), the entire ribbon feed path and the print head (12), being mounted at one side of the body member (20), and the drive motor (56) being mounted at a second side of the body member (20), and wherein the solenoid operated actuator (24) is in direct heat conduction relationship with the body member (20).

Description

Title: Printing Apparatus

Description of Invention

This invention relates to a printing apparatus and more particularly but not exclusively to a printing apparatus of the thermal kind in which there is provided a print head having an array of printing elements which are selectively -energised under computer control, as relative movement is established between the print head and a substrate, to remove pixels of ink from an inked carrier ribbon and to apply them to the substrate to print an image.

Particularly in a factory environment where the printing apparatus may be mounted at or adjacent a production/packaging line such that it is not easily accessible, one problem with such thermal printing apparatus is the threading of the inked carrier ribbon around a ribbon feed path from a storage to a take-up spool, though a printing station where the print head is located, either to replace used ribbon, or for re-threading in the event of ribbon breakage, which is not uncommon. This problem has been solved to a degree in known printing apparatus by providing the ribbon storage and take-up spools, and guide :. rollers of the ribbon feed path, on a cassette which can be removed from the remainder of the printing apparatus, so that the ribbon can be threaded more a...

conveniently. However this solution has a cost penalty. S. S * S S * S.

** 25 Another issue with known thermal printing apparatus arises because of the requirement to move the print head in a first direction towards a printing position in which in use the print head is urged towards a substrate on which * an image is to be printed to transfer ink from the inked carrier ribbon which is disposed between the print head and the substrate to the substrate, and a second opposite, rest, position in which in use the print head is spaced away from any substrate to permit substrate to be moved to, through and from the printing station. Various proposals have been put forward to achieve this, the most successful hithertofore requiring the provision of a pneumatically operated actuator. However a pneumatically operated actuator requires a supply of compressed air which is not always readily available. Proposals have been put forward for moving print heads using electrical actuators, but because a significant force is required to urge the print head towards the substrate for successful printing, and so high power consumption actuators are required, this results in significant heat being produced which needs to be dissipated.

Particularly in a food environment e.g. a food production/packaging facility, it is undesirable to use for example, fans to dissipate heat.

According to a first aspect of the invention we provide a printing apparatus which includes a printing station at which a print head is provided, the print head being moveable in a first direction towards a printing position in which in use the print head is urged towards a substrate on which an image is to be printed to transfer ink from an inked carrier ribbon disposed between the print head and the substrate to the substrafe, and a second opposite, rest, position in which in use the print head is spaced away from any substrate to permit substrate to be moved to, through and from the printing station, there being a solenoid operated actuator for effecting print head movement under the control of a controller, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, the entire ribbon feed path and the print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member, and wherein the solenoid operated actuator is in direct heat conduction relationship with the body member.

The present invention enables a printing apparatus to be provided which does not require the ribbon to be provided on a removable cassette. This is because, with the storage and take-up spools, the ribbon feed path and the print head all being provided at one side of the body member, these are all readily accessible from the one side of the body member. Threading of the inked carrier ribbon may be more difficult, depending upon the location and accessibility of the apparatus in use, than in printing apparatus which have cassettes, but this disadvantage is outweighed by the cost savings of not having a cassette.

Moreover, the printing apparatus of the first aspect of the invention does not require a supply of compressed air to achieve print head movement between the first and second positions as an electrical actuator, i.e. solenoid operated, is provided, but heat produced by solenoid operation is dissipated by the body member as the actuator is in direct heat conducting relationship with the body member.

Desirably, the solenoid operated actuator includes a solenoid body including coils which when energised, move an armature of the actuator so as to move the print head towards the substrate, and there being a return mechanism *..S such as a spring, to move the armature away from the substrate when the *:*. coils are de-energised.

S S'S.

Desirably the solenoid body is mounted at the second side of the body member with at least a part of the solenoid body. For example, the soilenoid body may include a threaded part which is received by a threaded opening of the body member, so that the solenoid body is in direct thermal contact with the body member.

The body member may include at least one mounting pad by which the apparatus may be mounted in use, for example to a mounting bracket in a desired orientation in relation to, for example, a packaging, production line along which substrates are conveyed. The body member may include a main plate-like part and the mounting pad may extend transversely to the plate-like part, e.g. at an edge of the plate-like part. Preferably the mounting pad and plate-like part are integrally provid!d.

Preferably a plurality of such mounting pads are provided, for example at edges of the body member, for maximum flexibility in mounting, and any of the mounting pads may be used for mounting the printing apparatus.

In order to achieve maximum heat dissipation, if desired at least one heat sink device may be provided which may be secured e.g. by one or more fasteners to a mounting pad which is use, is unused for mounting the printing apparatus.

The heat sink device may include a base which may, when the device is mounted to a mounting pad, intimately contacts the mounting pad over a substantial area of the mounting pad, and the base including a plurality of fins which extend from the base outwardly of the mounting pad. S...

For maximum heat dissipation, the body member may be a monolithic cast structure, made for example in aluminium or another highly conductive, preferably metal or alloy, material. The mounting pad or pads may be integrally cast with the remainder of the body member.

According to a second aspect of the invention we provide a printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, and the print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member, and wherein the body member includes at least one integral mounting pad by which the apparatus may be mounted in use.

According to a third aspect of the invention we provide a printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, and the print head, being mounted on the body member at one side of the body member, and the drive motor being mounted on the body member at a : ... second side of the body member, and wherein the body member is a monolithic cast structure. *s * * * S

In each case, the printing apparatus may be of the kind in which both the storage and take-up spools are drivable by motors which are mounted at the second side of the body member. The motors may be DC motors and/or stepper motors, or any combination of these or any other kind of motor, the motors being controlled by the controller to move the ribbon around the ribbon feed path when required.

Desirably a drive shaft of the or each motor extends through the body member, and wherein at least one of the storage and take-up spools is received by a hub which is securable to the drive shaft at the one side of the body member, by a releasable connection.

It will be appreciated that inked carrier ribbon is supplied wound around a former to provide a spool and that different manufacturers of such ribbon may use farmers having different dimensions and constructions. By providing a hub to receive the spool which itself is removable from the drive shaft, different former sizes can be accommodated by changing the hub only to fit the former.

Moreover, because the hub is securable to the drive shaft at the one side of the body member, access is straightforward, and there is no need to access the motor at the second side of the body member to change any component to accommodate spools with differing sizes of farmers.

According to a fourth aspect of the invention we provide a printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on vihich an image is in use to be printed, to the substrate, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used es ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, the entire ribbon feed path and the print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member with a drive shaft thereof extending through the body member, and wherein the take-up spool is received by a hub which is securable to the drive shaft at the one side of the body member, by a releasable connection.

The hub may include a locking mechanism to lock the hub relative to the drive shaft.

To control the movement of ribbon around the ribbon feed path, for example to match ribbon speed to substrate speed as the substrate passes through the printing station and is printed upon, and/or where both the storage and take-up spools are driven by motors, the ribbon feed path may include an encoded roller device including a rotatable sleeve about which the ribbon passes, the encoder being operable to monitor rotation of the sleeve and to provide input to the controller indicative of ribbon speed and/or tension for the purpose of ribbon feed control. It will be appreciated that in the generality, slippage between the ribbon and guides of the ribbon feed path may not be detrimental to apparatus operation, but slippage between the sleeve of the encoded guide roller device and the ribbon could seriously affect ribbon feed control.

Desirably the encoded roller device includes a central member which is attached in use to the body member so as to extend to the one side thereof, and the sleeve being a cylindrical sleeve of frictional material which is receivable on the central member when the central member is attached to the body member. *sla

By virtue of such construction, the sleeve of frictional material may readily be replaced on the central member when worn, from the one side of the body member, again simplifying maintenance of the apparatus. s_s

According to a fifth aspect of the invention we provide a printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, the ribbon feed path including at least one guide roller device for guiding the carrier ribbon, and wherein the apparatus includes a body member, the storage and take-up spools, the entire ribbon feed path and the print head, being mounted at one side of the body member, and the guide roller device including a central member which is attached in use to the body member so as to extend to the one side thereof, and a cylindrical sleeve of frictional material which is receivable on the central member when the central member is attached to the body member, the sleeve being rotatable about the central member in response to ribbon movement around the ribbon feed path.

The guide roller device may include an encoder operable to monitor rotation of the sleeve and to provide input to the controller for the purpose of ribbon feed control.

It will be appreciated that in a printing apparatus in accordance with the invention, all of the components of the apparatus which are non-serviceable, e.g. the motor or motors, and the solenoid body where provided, are all at the second side of the body member, whilst all the components for which S..' maintenance operations may be required to be carried out, such as the print head, the storage and take-up spools, and components of the ribbon feed path, are all located at the one side of the body member.

Preferably the controller is at the second side of the body member, and . .! together with the other components at the second side of the body member, is encased by a cover which together with the body member provides a substantially closed enclosure.

At least the storage and take-up spools at the one side of the body member need not be enclosed, but if desired, at least the printing station may be partially enclosed.

The printing apparatus may be of the kind in which the print head includes an array of printing elements which in use, are selectively energised under computer control, as relative movement is established between the print head and a substrate, to remove pixels of ink from the inked carrier ribbon and to apply them to the substrate to print an image.

The print head may be carried on a mounting plate at the printing station, and the print head may be securable to the mounting plate in a first orientation in which the printing elements of the array are operable to print or optimally to print on a substrate moving in a first relative direction, and in second opposite orientation in which the printing elements of the array are operable to print or optimally to print on a substrate moving in a second relative direction opposite to the first relative direction.

Preferably a peel device is provided to facilitate the removal of pixels of ink from the inked carrier immediately downstream of the print head. The peel device may, when the print head is secured to the mounting plate in the first orientation, be mounted on the mounting plate at a first position immediately downstream of the array, and may be relocatable to a second position immediately downstream of the array when the print head is secured to the mounting plate in the second orientation. I. S * S *S

Thus the print head, and peel device, may be simply re-handed to suit the relative direction of movement of the substrate to the print head.

S S..

In one embodiment relative movement between the print head and the substrate is achieved by substrate movement whilst the print head is maintained stationary at the printing station, and moving the inked carrier ribbon too, relative to the print head. Thus the mounting plate where provided, may be fixed to the one side of the body member at the printing station.

In another example though, relative movement between the print head and substrate is achieved by moving the print head at the printing station along the substrate. Thus the mounting plate may be secured to a motive device, such as a drive belt which is driven by a drive belt motor, which drive belt motor desirably is at the second side of the body member. The drive belt motor may have a shaft which extends through the body member to a drive sprocket at the one side of the body member, there being an idler pulley for the drive belt also mounted to the one side of the body member, the drive belt being entrained about the drive sprocket and idler pulley and being moveable when the drive belt motor is actuated to move the belt and hence the print head.

Desirably a guide rail is provided at the one side of the body member, and the mounting plate includes a carriage which moves along the guide rail as the drive belt is moved, positively to guide the print head.

Of course if desired, relative movement between the pint head and substrate and ribbon, may be achieved by both substrate movement through the printing station and additionally print head movement at the printing station relative to the body member.

S

In each case to effect movement of the print head towards and away from the *5*e. . substrate, a transmission may be provided between the solenoid operated :*. actuator and the print head which permits. some print head universal ** movement for compliance, for example if the substrate surface on which the image is to be printed is not exactly parallel to array of printing elements. S..

Where the print head is moveable at the print station during printing and to return the print head to a start-of-print position after printing, the transmission may include a running bar which is moveable by the solenoid operated actuator to effect print head movement towards and away from the substrate, and the print head or mounting plate may carry a roller which is moveable along the running bar so that print head movement towards and away from the substrate may be effected by the solenoid operated actuator at any position along the substrate to which the print head may be moved at the printing station during printing.

If desired a mechanically operated switch may be provided at the one side of the body member, which is operated when the print head is in a home position prior to or subsequent to performing a print.

Particularly where the printing apparatus includes both a motor to drive the take-up spool and a motor to drive the storage spool, the ribbon feed path may include a ribbon tension sensing mechanism to sense the tension in the inked carrier ribbon and to provide input to the controller for the purpose of ribbon tension control. The tension sensing mechanism may include an elongate ribbon guide which extends perpendicularly to the ribbon feed direction, and is rotatable about a rotational axis and is displaceable about an axis parallel to but spaced from its own rotational axis, against a spring, as carrier ribbon tension increases. The extent of such displacement may be determined by a displacement sensing device, preferably a solid state sensing device such as a Hall effect or similar sensor. S...

The ribbon guide is preferably provided at the one side of the body member but the displacement sensing device may be provided at the second side of . the body member, for example, integrally with a printed circuit board of the controller, or separately therefrom as desired.

* S 30 Embodiments of the invention will now be described with reference to the accompanying drawings in which:-FIGURE 1 is an illustrative perspective view of one side of a printing apparatus in accordance with the invention from a rear, with inked carrier ribbon spools omitted for clarity; FIGURE 2 is an enlarged perspective illustrative view of a print head and mounting plate, from the front, of the apparatus of figure 1; FIGURE 3 is an enlarged perspective illustrative view of the print head and mounting plate of figure 2 from beneath, and a carriage and drive belt; FIGURE 4A is a perspective illustrative view from above of a removable hub for a ribbon spool of the apparatus of figure 1; FIGURE 4B is a perspective illustrative view of the hub of figure 4A from beneath, showing a spool drive motor and a drive shaft connector of the apparatus of figure 1; FIGURE 5 is an illustrative sectional view of an encoded ribbon guide for use in the application of figure 1; FIGURE 6 is an illustrative perspective view of the print head and mounting plate without any protective cover, and a transmission and solenoid operated actuator of the apparatus of figure 1; FIGURE 7 is a cross sectional view through a ribbon guide of a ribbon feed path of the apparatus of figure 1; FIGURE 8 is a view similar to figure 1 of a printing apparatus in accordance with the invention but from the front, and with the inked carrier ribbon spools in place and the ribbon extending around a ribbon feed path; S..

FIGURE 9 is a view of the apparatus of figure 8 from beneath, with an p...

encasement omitted for clarity. p. * * S

Referring to figures 1, 8 and 9 there is shown a printing apparatus 10 which includes a printing station 11 at which a print head 12 is provided. The print head 12 is operable to print an image on the substrate moving relative to the print head 12, by transferring ink from an inked carrier ribbon (shown at 14 in figures 8 and 9 but not seen in figure 1) to the substrate.

The substrate may be an article such as a packaged article from a production/packaging line, passing or positioned adjacent to the printing station 11, or the substrate may be a label or the like which is fed to the printing station 11. In each case the inked carrier ribbon 14 is provided on a ribbon storage spool 15, and passes around a ribbon feed path which will be described in more detail below, through the printing station 11 and hence to a take up spool 16.

According to the present invention, there is provided a body member 20 which in this example is a monolithic cast aluminium member. The storage and take-up spools 15, 16 the entire ribbon feed path, and the print head 12 are all mounted at one side of the body member 20, i.e. the uppermost side as seen in figures 1 and 8, whereas other printer apparatus 10 components such as drive motors for the storage and take up spools 15, 16 and a motor for moving the print head 12 as hereinafter described, as well as a controller 21 (see figure 9) are provided at a second, underside, of the body member 20.

To effect printing, the print head 12 is moveable and is urged towards the substrate with the inked carrier ribbon 14 between the print head 12 and the substrate. After printing, the print head 12 is moved away from the substrate, to facilitate movement of the substrate from the printing station 11, and to ** facilitate movement of another substrate to the printing station 11 for S..

subsequent printing. *5S*

As will be described in more detail with reference to figure 6, this movement of the print head 12 towards and away from the substrate is effected by a solenoid operated actuator 24. The solenoid operated actuator 24 includes a solenoid body 25 including solenoid coils, and an armature 26 which is * 30 moveable when the solenoid coils are electrically energised. A return mechanism, such as a spring may be provided internally of the solenoid body to withdraw the armature 26 into the solenoid body 25 when it is desired to move the print head 12 away from the substrate although this is otherwise achieved in this example as will be explained below. It can be seen from figure 9 that the solenoid body 25 is provided at the second side of the body member 20. The solenoid body 25 is generally cylindrical whereas the body member is in the main, plate-like, the armature 26 being moveable through the body member 20 to a transmission for moving the print head 12 towards and away from the substrate. The cylindrical solenoid body 25 has, towards an axial end thereof, a threaded part which is received in a threaded opening in the body member 20, so that the solenoid body 25 is in intimate contact with the body member 20 so that heat which is created as a result of actuation of the solenoid operated actuator 24 is efficiently dissipated to the body member 20, which desirably is made of a highly conductive material, in the present case, aluminium.

Referring to figure 2, it can been seen that the print head 12 is secured to a mounting plate 28 by four fasteners 29. The print head 12 is of the kind having along an edge thereof, an array 30 of printing elements. A large number of printing elements typically would be provided in the array 30, each printing element being selectably energisable by the computer controller 21, to effect heating in order to soften and remove ink on the inked carrier ribbon 14 which is thus transferred onto the substrate to print a row of pixels selected from the array 30. The substrate and print head 12 then relatively move to S..

another position, where the same or different printing elements of the array 30 are selectively energised in order to print the next row of the image and so on for printing an entire image. It can be seen in figure 2,.that a peel device 32 ** provided, around which the inked carrier ribbon 14 is entrained, to facilitate removal of the softened pixels of ink and their transference to the substrate. S.. S. *

* .: 30 The print head 12 is "handed", i.e. at least optimally prints when the printing elements of the array 30 are particularly positioned relative to the substrate and peel device, depending upon the relative direction of movement of the print head 12 to the substrate. In figure 8, for example, the direction of movement of the substrate relative to the print head 12 is indicated by the arrow A which is the same direction in which the ribbon 14 is moved relative to the punt head 12. In another example, where substrate movement relative to the print head 12 is in a direction opposite to arrow A, the print head 12 would require re-handing and the inked carrier ribbon 14 would require moving in the opposite direction relative to the print head 12.

From figure 2 it will be appreciated that re-handing of the print head 12 can simply be achieved by releasing the fasteners 29 and moving the print head 12 from the first orientation shown in figure 2, to an opposite orientation because at each end of the print head 12 there is a substantially identical fixing plate 33. Thus the fasteners 29 may be re-engaged with the mounting plate 28, but through openings provided onthe opposite fixing plate 33.

The peel device 32 also requires repositioning and this may be easily achieved because the mounting plate 28 has an alternative location 34 to which the peel device 32 may be relocated.

The body member 20 includes three integral mounting pads 35, 36 and 37 provided at edges of the plate-like part of the member 30. Mounting pad 35 extends generally perpendicularly to the plate-like extent of the remainder of :... the body member 20 at a rear edge of the body member 20 opposite to the S...

printing station 11. The mounting pad 36 is provided at one other edge of the plate-like, body member 20 and is a substantially identical in construction to * * the mounting pad 35 at the rear edge.

Mounting pad 37 is provided at an edge of the plate-like part of the body *..: 30 member 20 substantially oppositely mounting pad 36.

Each of the mounting pads 35, 36 and 37 have openings 38, in substantially identical positions. The mounting pads 35, 36 and 37 each permit of mounting the printing apparatus 10 by any one of them so as to give a wide variety of alternative mounting positions of the printing apparatus 10 for example relative to a production/packaging line along which substrates are conveyed. In practice, a bracket may be provided to which any of the mounting pads 35, 36 and 37 may be secured by fasteners. Fine adjustment of the position of the printing apparatus 10 relative to a production line, for example, may be achieved by one or more adjustment mechanisms of the bracket to which the printing apparatus 10 may be mounted.

Each of the mounting pads 35, 36 and 37, being integrally cast with the remainder of the plate-like body member 20, also provide a function of assisting dissipation of heat, particularly heat generated by operation of the solenoid operated actuator 24. Moreover, if desired, as indicated in figure 1, any mounting pad 35, 36 or 37 which is unused for mounting the printing apparatus 10 may have secured to it, a heat sink device 40. In the present example, the heat sink device 40 includes a base member 41 which lies in intimate contact with the mounting pad 35 (or 36 or 37), with there being a plurality of fins 42 extending from the base member 41 to provide a large surface area around which air may circulate, in order to dissipate heat.

In the present example, the printing apparatus 10 is of the kind in which the a...

print head 12 is moveable at the printing station 11 along a substrate which may be stationary at the printing station 11 or moving, in order to effect relative movement between the print head 12 and the substrate, for printing. S.

:: Referring to figure 3, it can be seen that the mounting plate 28 has on a lower surface opposite to that on which the print head 12 is mounted, a carriage 50.

Secured to the one side of the body member 20, is a guide rail 51 (shown isolated from the body member 20 in figure 3) along which guide rail 51, the carriage 50 and hence the mounting plate 28 and print head 12, are guided during movement along the substrate, positively to ensure that the mounting plate 28 at least moves only linearly.

Movement of the mounting plate 28 and carriage 50 relative to the guide rail 51, is achieved by a drive belt 52 which in this case is a toothed belt which is entrained about a drive sprocket 53 and an idler pulley 54. The drive sprocket 53 is carried on a drive shaft of a drive belt motor 49 (see figure 9) which is located at the second side of the body member 20. The drive shaft of the motor 49 extends through the body member 20 and the drive sprocket 53 is provided at the one side of the body member 20.

As the drive belt motor 49 is actuated, the drive sprocket 53 will rotate, as the carriage 50, or a part thereof indicated at 51, is secured to the drive belt 52.

Movement of the drive belt 52 will move the carriage 50, and print head 12 in a direction depending upon the rotational direction of the drive motor 49. Thus during printing, the print head 12 may be moved along the substrate to print the image, with the print head 12 moved towards the substrate by the solenoid operated actuator 24, and after printing, when the print head 12 is moved away from the substrate, the belt drive motor 49 may be rotated in an opposite direction to return the print head 12 to a home position ready for performing the next print. *

It can be seen that the drive belt 52 is provided at the one side of the body member 20 and is thus accessible from the one side of the body member 20, s* as are the storage and take up spools 15, 16 and the print head 12 and mounting plate 28. Thus all parts of the printing apparatus 10 which may require service maintenance or the like, are provided on the one side of the body member 20, whereas all the non-serviceable parts, namely the belt drive motor 54, solenoid operated actuator 24, and storage and take up spool drive motors 56 and 57, are provided at the second side of the body member 20, with the controller 21.

The second side of the body member 20 may be encased by a cover to protect those non-serviceable components although the parts on the one side of the body member 20 need not be so encased unless required. Practically, at least a partial cover of the printing station 11 may be provided and particularly, for example in a food environment, i.e. a food packaging facility, it may be desirable or necessary for each of the components on the one side of the body member 20 to be encased.

Nevertheless, even where the printing apparatus 10 is located in a generally inaccessible position, where any cover covering the components on the one side of the body member 20 is removed, the layout on the body member 20 of the various components and the simplicity of the design, facilitates maintenance and adjustment of the various serviceable parts.

Further features of the printing apparatus 10 further facilitate this. For example, referring to figures 4A and 4B, there is illustrated a ribbon take-up spool motor 56 which is as indicated above, is in practice located at the second side of the body member 20. The drive shaft 57 of the motor 56 extends through the body member 20 and receives a connector 58 at the one side of the body member 20. The ribbon take-up spool 16, i.e. ribbon wound about a former, is mounted on a hub 60 which is removably received on the drive shaft 57, with the connector 58 extending inside an internal opening 61 of the hub 60.

S

Because different manufacturers of ribbon utilise different sizes and configurations of formers around which the ribbon is wound, such a former *..: 30 being illustrated at 62 in figure 8, providing a removable hub 60 enables a hub appropriate for any particular inked carrier ribbon former simply to be provided. The hub 60 is a lightweight component, for example of plastic, so as not to add to the inertia of the ribbon spool carried on the hub 60.

The hub 60 includes a locking mechanism so that the hub 60 positively locks onto the connector 58 and hence the drive shaft 57 of the motor 56 until a resilient tag 64 is urged, for example with a screwdriver or other tool, to release the locking mechanism and permit the hub 60 to be removed from the connector 58 and drive shaft 57.

Although the hub 60 for the take-up spool drive motor 56 has been described, the hub for the storage spool 15 may be of identical construction, the storage spool drive motor 55 having a drive shaft and connector substantially identical to the drive shaft 57 and connector 58 of the take-up spool drive motor 56 described and shown in figures 4A and 4B.

The ribbon feed path around which the inked carrier ribbon 14 passes from the supply spool 15 to the storage spool 16 through the printing station 11 will now be described with particular reference to figures 1 and 8.

In this example, the ribbon 14 is so called, externally wound, i.e. the ink which is to be deposited on the substrate during printing operations, is carried on a radially externally outside wound surface of the ribbon 14 of the storage spool 15.

As the ribbon 14 leaves the storage spool 15, the ribbon passes around an encoded ribbon guide roller device 70 which is shown in more detail in figure 5.

The encoder ribbon guide roller device 70 includes a central member 71 or : 30 spindle, which is journalled in bearings 72 in the body member 20, or at least in a fitment 20a received in an opening or corner recess of the body member as in the example shown, so as to extend from the body member 20 substantially at one side thereof. The central member 71 carries a sleeve 73 of friction material which is retained relative to the central member 71, is a cap 74 which is secured to the central member 71 or spindle, by a screw threaded fastener 76, so that the sleeve 73 is fast with the central member 71. The central member 71 carries at an end thereof at the second side of the body member 20, a dual pole magnet 74 or other element, the rotation of which about a rotational axis D is sensed by rotation sensing device, to monitor rotations of the sleeve 73 and provide input to the controller 21 for the purpose of ribbon feed control.

Because it is important for accurate ribbon feed control for the sleeve 73 and central member 71 to rotate in response to movement of ribbon 14 entrained about the encoder roller device 70, the sleeve 73 is readily replaceable from the one side of the body member 20, by releasing the cap 74 which unscrews.

Thus there is no need for a user or engineer to access the second side of the body member 20 to service and maintain the encoded roller device 70.

After passing around the encoded roller device 70, the ribbon 14 then passes via a ribbon tension sensing mechanism 80, to the printing station 11. The ribbon tension sensing mechanism 80 includes an elongate ribbon roller guide 81, which in this example includes a roller sleeve which is rotatable about a rotational axis E in response to movement of the ribbon 14 which is entrained about the roller 81. The roller ribbon guide 81 is carried by a mounting 83 -V., which is mounted to and rotatable relative to the body member 20 about an * axis C parallel to but spaced from the axis of rotation E of the guide ribbon roller device 81, against the force of a restoring spring (not shown) as ribbon tension in the ribbon feed path increases. The mounting 83 includes a moveable part 84 which is displaced as the roller guide 81 is moved about the . 30 axis C of the ribbon tension sensing mechanism 80.

The extent of such displacement is determined by a displacement sensing device 85 provided at the second side of the body member 20, such as a Hall effect sensor or similar. The moveable part 84 may, for example, carry one or more magnets, the movement of which are sensed, although any other displacement sensing device may be provided. In each case, the displacement sensing device 85 provides input to the controller 21 which controls the operation of the ribbon storage spool motor 55, and the ribbon take-up spool 56 in response, in order to maintain the tension in the ribbon path between the storage and take up spools 15, 16, within acceptable limits.

After passing over the array 30 of printing elements of the print head 12 at the printing station 11, the ribbon 14 is entrained about the peel device 32. In this example, the peel device 32 is constructed as shown in figure 7.

A central member 90, which may be a simple threaded fastener, is received in an opening of the mounting plate 28, after a bearing sleeve 91 has been received on the central member 90. The bearing sleeve 91 may be made of a metallic and low friction material, and in use is held between a head 92 of the fastener central member 90, and the mounting plate 28, with a washer 93 interposed between the sleeve 91 and the mounting plate 28. Over the bearing sleeve 91 there is provided a roller sleeve 95 which is thus free to rotate about the bearing sleeve 91 or with the bearing sleeve 91 about the central member 90, in response to movement of ribbon 14 which is entrained about the friction sleeve 95. A washer 94 is provided beneath the head 92 of * , the central fastener 90 and each of the bearing sleeve 91 and friction sleeve * * 95, again to free the friction sleeve 95 and/or bearing sleeve 91 for rotation. ****

In an embodiment with other guide elements around the ribbon feed path such as rollers for example, preferably such rollers would be constructed similarly to the peel device 32 illustrated in figure 7, so that the guide device may be serviced from the one side of the body member 20 only, e.g. to replace the friction sleeve 35, or indeed the guide device in its entirety.

After passing around the peel device 32, the ribbon is guided around a further guide element 99 which may be similar in construction to the ribbon tension mechanism 80, and hence to a final ribbon guide element 96 adjacent the take up spool 16, and hence onto the take up spool 16.

Referring now particularly to figure 6, the mechanism by which movement is transmitted from the solenoid operated actuator 24 to the print head 12 to move the print head 12 towards and away from the substrate, will be described. Again the body member 20 has been omitted for clarity and the print head 12 is shown without its fixing plates 33 and surrounding cover.

The armature 26 of the solenoid operated actuator 24 is secured to a limb 100 of the transmission, which is generally at right angles to a cable guide 101.

The cable guide 101 has secured to it a running bar 103 which extends for the full extent of permitted print head movement 12 along the guide rail 50. The print head 12 carries a roller 106 which is moveable along the running bar 103 during print head 12 movement, and the roller 106 is carried on a pivot arm 108 which is pivotable about a generally upright axis as seen in figure C, at F, to permit the print head 12 to move towards and away from the substrate, and the pivot arm is moveable, to a smaller extent, about a generally horizontal axis G to permit of compliance of the print head 12, for example where the S.. I * . .. 25 substrate is presented at the print station 11, with a surface of the substrate *:*. on which the image is to be printed, not being exactly parallel to the array 30 * of printing elements of the print head 12. **

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It can be seen that when the armature 26 of the solenoid operated device 25 30 is extended relative to the solenoid body 25, the limb 100, cable guide 101, and running bar 103 will all move about a generally horizontal axis H which is fixed relative to the body member 20, by virtue of the limb 100, cable guide 101 and running bar 103 being carried on a pivot pin which extends along the axis H, ends of the pivot pin 104 being mounted in respective pivot housings and 111 which are fixed to the one side of the body member 20.

The roller 106 carried by the pivot arm 108, can thus not only move along the running bar 103, but as the running bar 103 moves about the horizontal pivot axis H by the action of the armature 26, the roller 106 may move about a central axis of the running bar 103, which is cylindrical.

Thus, the generally vertical movement (as seen in figure 6) of the armature 26 when the coils of the solenoid actuated device 24 are energised, is converted by the transmission into a forward movement of the print head 12 towards the substrate. During printing, the coils of the solenoid actuated device 24 remain energised, so that a constant urging force is applied by the print head 12 when in the printing position, through the adjacent inked carrier ribbon (not seen in figure 6) to the substrate for effective transference of pixels of ink from the inked carrier ribbon 14 to the substrate.

When the coils of the solenoid actuated device 24 are de-energised, the armature 26 may be withdrawn into the solenoid body 25 by the internal spring where provided, and the limb 100, cable guide 101 and running bar 103 will be moved back about horizontal axis H, to permit the print head 12 to move back away from the substrate. S... * S *SS.

In the example though, the solenoid operated actuator 24 does not include any spring of its own to return the armature 26 to the rest position, but the *..* necessary restoring force is provided by a torsion spring or other spring device which acts about upright axis F, to oppose forward movement of the print *** 30 head 12 towards the substrate. Further alternatively, if desired, the coils of the solenoid operated device 24 may be energised temporarily oppositely to when the print head 12 is urged forwards, positively to withdraw the armature back into the solenoid body 25.

Desirably, each of the take-up and pay out spool motors 55, 56 are stepper motors, but one or other of them could be a DC or other kind of motor, or indeed both of the motors 55 and 56 could be other than stepper motors.

The drive belt motor 49 is also preferably a stepper motor, although another kind of motor could be used as desired.

The invention may be applied to a printing apparatus 10 in which relative movement between the print head 12 and the substrate is achieved without movement of the print head 12 along the substrate. In this example, the drive belt motor 54 may not be required, or at least, the print head 12 may be affixed relative to the one side of the body member 20 rather than being carried on a carriage 50 and drive belt 52 arrangement. It is envisaged that a printing apparatus 10 would be provided with the facility for either mounting the print head 12 on a carriage 50 for movement at the printing station 11 along the substrate or for the print head 12 to be affixed to the one side of the body member 20, depending upon the desired application of the printing apparatus 10. In another embodiment, the substrate may move at the printing station 11 during printing, and additionally the print head 12 may be moved along the substrate in either direction in order to achieve an appropriate speed :

. of relative motion between the print head 12 and the substrate for effective * SIS and efficient printing...DTD: S. S -In another example, the inked carrier ribbon 14 may be internally wound, i.e. S...

the ink carried by the ribbon 14 may be provided on an internally wound surface of the ribbon 14 rather than the external surface as in the example *". 30 described in which case, adjustment of the control mechanism for rotating the spools 15, 16 to achieve ribbon 14 movement in an appropriate direction around the ribbon feed path, may need to be undertaken.

Various other modifications are possible without departing from the scope of the invention. For example, instead of a sprung further ribbon guide element 99 in addition to the ribbon tension mechanism 80, a simple guide roller may be sufficient.

In place of guide rollers 96, 99 to guide the ribbon 14 around the ribbon feed path, simple guide pins may be adequate.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. S. *. * S.. SI'S * S S... *S S * I. * II

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Claims

CLAIMS

1. A printing apparatus which includes a printing station at which a print head is provided, the print head being moveable in a first direction towards a printing position in which in use the print head is urged towards a substrate on which an image is to be printed to transfer ink from an inked carrier ribbon disposed between the print head and the substrate to the substrate, and a -second opposite, rest, position in which in use the print head is spaced away from any substrate to permit substrate to be moved to, through and from the printing station, there being a solenoid operated actuator for effecting print head movement under the control of a controller, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, the entire ribbon feed path and the print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member, and wherein the solenoid operated actuator is in direct heat conduction relationship with the body member.

2. An apparatus according to claim I wherein the solenoid operated actuator includes a solenoid body including coils which when energised, move : an armature of the actuator so as to move the print head towards the 25 substrate, and there being a return mechanism to move the armature away from the substrate when the coils are de-energised. I.e

3. An apparatus according to claim I or claim wherein the solenoid body is mounted at the second side of the body member with at least a part of the solenoid body, in direct thermal contact with the body member.

4. An apparatus according to any one of the preceding claims wherein the body member includes at least one mounting pad by which the apparatus may be mounted in use.

5. An apparatus according to claim 4 wherein the body member includes a main plate-like part and the mounting pad extends transversely to the plate-like part, at an edge of the plate like part.

6. An apparatus according to claim 4 or claim 5 wherein the mounting pad and plate-like part are integrally provided.

7. An apparatus according to any one of claims 4 to 6 wherein a plurality of mounting pads are provided at edges of the body member.

8. An apparatus according to claim 7 wherein at least one heat sink device is provided secured to a mounting pad which is use, is unused for mounting the printing apparatus.

9. An apparatus according to claim 8 wherein the heat sink device includes a base which may, when the device is mounted to a mounting pad, intimately contacts the mounting pad over a substantial area of the mounting pad, and the base including a plurality of fins which extend from the base :. outwardly of the mounting pad. *. 25

10. An apparatus according to.any one of the preceding claims wherein the *..: body member is a monolithic cast structure, made in a highly conductive material. * S * S.. S. a SS

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11. An apparatus according to claim 10 wherein dependent upon claim 4 wherein the mounting pad or pads is/are integrally cast with the remainder of the body member.

12. A printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, a storage spool which stores a supply of the inked carrier ribbon, a take- up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, and the print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member, and wherein the body member includes at least one integral mounting pad by which the apparatus may be mounted in use.

13. A printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, a storage spool which stores a supply of the inked carrier ribbon, a take- up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spooi being rotatable by a drive motor, * 25 and wherein the apparatus includes a body member, the storage and take-up spools, and the print head, being mounted on the body member at one side of *** the body member, and the drive motor being mounted on the body member at a second side of the body member, and wherein the body member is a :.*:; monolith, c cast structure.

* .. 30 14. An apparatus according to any one of the preceding claims wherein the printing apparatus is of the kind in which both the storage and take-up spools are drivable by motors which are mounted at the second side of the body member.

15. An apparatus according to claim 14 wherein the motors are controlled by the controller to move the ribbon around the ribbon feed path when required.

16. An apparatus according to any one of the preceding claims wherein a drive shaft of the or each motor extends through the body member, and at least one of the storage and take-up spools is received by a hub which is securable to the drive shaft at the one side of the body member, by a releasable connection.

17. A printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, at least the take-up spool being rotatable by a drive motor, and wherein the apparatus includes a body member, the storage and take-up spools, the entire ribbon feed path and the *::::* 25 print head, being mounted at one side of the body member, and the drive motor being mounted at a second side of the body member with a drive shaft 4. :: thereof extending through the body member, and wherein the take-up spool is s..

received by a hub which is securable to the drive shaft at the one side of the body member, by a releasable connection.

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18. An apparatus according to claim 17 wherein the hub includes a locking mechanism to lock the hub relative to the drive shaft.

19. An apparatus according to any one of the preceding claims wherein the ribbon feed path includes an encoded roller device including a rotatable sleeve about which the ribbon passes, the encoder roller device being operable to monitor rotation of the sleeve and to provide input to the controller indicative of ribbon speed for the purpose of ribbon feed control.

20. An apparatus according to claim 19 wherein the encoded roller device includes a central member which is attached in use to the body member so as to extend to the one side thereof, and the sleeve being a cylindrical sleeve of frictional material which is receivable on the central member when the central member is attached to the body member.

21. A printing apparatus which includes a printing station at which a print head is provided, the print head being operable to transfer ink from an inked carrier ribbon disposed between the print head and a substrate on which an image is in use to be printed, to the substrate, the apparatus further including a storage spool which stores a supply of the inked carrier ribbon, a take-up spool for taking up used ribbon, and a ribbon feed path between the storage and take-up spools through the printing station, the ribbon feed path including at least one guide roller device for guiding the carrier ribbon, and wherein the apparatus includes a body member, the storage and take-up spools, the entire S...

w' 25 ribbon feed path and the print head, being mounted at one side of the body member, and the guide roller device including a central member which is * attached in use to the body member so as to extend to the one side thereof, *.* and a cylindrical sleeve of frictional material which is receivable on the central S.,. member when the central member is attached to the body member, the sleeve 30 being rotatable about the central member in response to ribbon movement around the ribbon feed path.

22. An apparatus according to claim 21 wherein the guide roller device includes an encoder operable to monitor rotation of the sleeve and to provide input to the controller for the purpose of ribbon feed control.

23. an apparatus according to any one of the preceding claims wherein the controller is at the second side of the body member.

24. An apparatus according to any one of the preceding claims in which the print head includes an array of printing elements which in use, are selectively energised under computer control, as relative movement is established between the print head and a substrate, to remove pixels of ink from the inked carrier ribbon and to apply them to the substrate to print an image.

25. An apparatus according to claim 24 wherein the print head is carried on a mounting plate at the printing station, and the print head is securable to the mounting plate in a first orientation in which the printing elements of the array are operable to print or optimally to print on a substrate moving in a first relative direction, and in an opposite second orientation in which the printing elements of the array are operable to print or optimally to print on a substrate moving in a second relative direction opposite to the first relative direction.

26. An apparatus according to claim 25 in which a peel device is provided to facilitate the removal of pixels of ink from the inked carrier immediately *::::* 25 downstream of the print head, the peel device, when the print head is secured to the mounting plate in the first orientation being mounted on the mounting plate at a first position immediately downstream of the array, and being relocatable to a second position immediately downstream of the array when the print head is secured to the mounting plate in the second orientation. *. .

S SS *.

27. An apparatus according to any one of claims 24 to 26 wherein relative movement between the print head and the substrate is achieved by substrate movement whilst the print head is maintained stationary at the printing station, and moving the inked carrier ribbon too, relative to the print head.

28. An apparatus according to claim 27 wherein the mounting plate where provided, is fixed to the one side of the body member at the printing station.

29. An apparatus according to any one of claims 24 to 28 wherein relative movement between the print head and substrate is achieved by moving the print head at the printing station along the substrate.

30. An apparatus according to claim 29 wherein the mounting plate is secured to a motive device, being a drive belt which is driven by a drive belt motor, which drive belt motor at the second side of the body member.

31. An apparatus according to claim 30 wherein the drive belt motor has a shaft which extends through the body member to a drive sprocket at the one side of the body member, there being an idler pulley for the drive belt also mounted to the one side of the body member, the drive belt being entrained about the drive sprocket and idler pulley and being moveable when the drive belt motor is actuated to move the belt and hence the print head.

32. An apparatus according to claim 31 wherein a guide rail is provided at *1S* i... 25 the one side of the body member, and the mounting plate includes a carriage which moves along the guide rail as the drive belt is moved, positively to guide * the print head.

33. An apparatus according to any one of claims 24 to 32 wherein relative *" 30 movement between the print head and substrate and ribbon, is achieved by both substrate movement through the printing station and additionally print head movement at the printing station relative to the body member.

34. An apparatus according to any one of the preceding claims wherein to effect movement of the print head towards and away from the substrate, a transmission is provided between the solenoid operated actuator and the print head which permits some print head universal movement for compliance.

35. An apparatus according to claim 34 wherein where the print head is moveable at the print station during printing and to return the print head to a start-of-print position after printing, the transmission includes a running bar which is moveable by the solenoid operated actuator to effect print head movement towards and away from the substrate, and the print head or mounting plate includes a roller which is moveable along the running bar so that print head movement towards and away from the substrate may be effected by the solenoid operated actuator at any position along the substrate to which the print head may be moved at the printing station during printing.

36. An apparatus according to claim 35 wherein a mechanically operated switch is provided at the one side of the body member, which is operated when the print head is in a home position prior to or subsequent to performing a print.

37. An apparatus according to any one of the preceding claims in which the 25 printing apparatus includes both a motor to drive the take-up spool and a motor to drive the storage spool, the ribbon feed path including a ribbon tension sensing mechanism to sense the tension in the inked carrier ribbon and to provide input to the controller for the purpose of ribbon tension control. S. sa

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 30 38. An apparatus according to claim 37 wherein the tension sensing mechanism includes an elongate ribbon guide which extends perpendicularly to the ribbon feed direction, and is rotatable about a rotational axis and is displaceable about an axis parallel to but spaced from its own rotational axis, against a spring, as carrier ribbon tension increases.

39. An apparatus according to claim 38 wherein the extent of such displacement is determined by a displacement sensing device.

40. An apparatus according to claim 39 wherein the elongate ribbon guide is provided at the one side of the body member and the displacement sensing device is provided at the second side of the body member.

41. A printing apparatus substantially as hereinbefore before described with reference to and/or as shown in the accompany drawings.

42. Any novel feature or novel combination of features described herein and/or in the accompanying drawings. S. * , * S.. *5SS

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