WO1992001563A1

WO1992001563A1 - Device for drying and guiding the printed material in an inkjet printing device

Info

Publication number: WO1992001563A1
Application number: PCT/DE1991/000505
Authority: WO
Inventors: Hans Kusmierz; Otmar Irro
Original assignee: Mannesmann Ag
Priority date: 1990-07-26
Filing date: 1991-06-14
Publication date: 1992-02-06
Also published as: EP0540531A1; JPH05509044A

Abstract

In order to dry and guide printed material in an ink-jet printing device (8), the invention calls for a guide element (4) to be detachably or rigidly mounted on an ink-drying unit (1, 1a) in the printed-material (3) output zone (AB) between the printing station (5) and the printing-device output (ATB). The guide element (4) has a clip-on device (411) with two cheeks (410) which is moulded out to form a shaped body (41) and is made preferably of plastic. Rotatably mounted between the cheeks (410) is a notched wheel (40) with sharp-edged, obtuse-angled serrations (400). Part (401) of the notched wheel (40) projects into an opening (101) at the output end of a heated shaft (100) in the ink-drying unit (1, 1a). The function of the notched wheel (40) is to guide the printed material (3) conveyed through the heated shaft (100) and the output opening (101) out of the printing device (8) without it being smudged.

Description

Device for drying and guiding printed record carriers in inkjet printing devices

The invention relates to a device for guiding printed record carriers in printing devices according to claim 1.

The management of printed record carriers, such as single sheets or continuous formats made of paper, film and cardboard, in printing devices, e.g. B. needle, type, thermal transfer, inkjet and electrophotographic printers, then proves to be problematic when the freshly printed record carrier is to be guided along the printed image side. This problem occurs particularly with inkjet printers. It is particularly striking in those inkjet printers which work with non-penetrating ink, for example water ink. The advantage of water ink over penetrating ink, e.g. B. glycol ink, is that the print image created with water ink is of better quality. In contrast, however, the drying time of the non-penetrating ink is significantly longer than that of the glycol ink, so that the risk of blurring of the printed image during transport of the "freshly" printed recording medium extremely corrugated by the water content of the ink (80%) in the Ink jet printer exists. In the inkjet printer, printed image blurring occurs particularly where the record carrier to be transported has to overcome bottlenecks on the transport route. Such problem areas are in the ink jet printer in the area of the ink print head, at the outlet opening of the ink jet printer for the recording medium and in the immediate vicinity of a heating device. The problem of the heating device is necessary in inkjet printers working with non-penetrating ink in order to accelerate the drying process of the ink. The printed record carrier For this purpose, the heating device must be guided as close as possible to the heating device with a limited length of time. Heating devices used in ink jet printers include, for example, specially designed heating saddles and an ink drying aid, as described in European patent application 89118830.2. The ink drying aid then consists of an electrical heater, which is arranged in a heat shaft for receiving the printed recording medium. Targeted activation of the electrical heating creates a homogeneous temperature distribution in the heat shaft. The ink drying aid is arranged from several components directly above the ink print head in a holder of the ink jet printer.

The object of the invention is to construct a device for drying and guiding printed record carriers in ink jet printing devices, which is designed with little effort, requires a relatively low power consumption for drying, in which deformation of the record carrier prevents drying and in which the printed carrier Record carrier without visible print image disturbances for different materials and formats of the record carrier is guided through bottlenecks in an outlet area of the printing device.

The object according to the invention is achieved by the features specified in patent claim 1.

Advantageous developments of the invention are specified in the subclaims.

In the invention, the paper printed with the aid of an ink print head is passed through a heat shaft with opposing heating surfaces which are black due to better radiation. The mutual illumination in the heat shaft achieves a homogeneous temperature distribution in the heat shaft with a low power requirement. The record carrier heats up due to heat radiation and heat transfer the dark ink absorbs the heat quickly on the printed side and thus dries quickly. The rising air flow in the heat shaft, which acts as a chimney, promotes drying and the moisture is removed.

Due to the heating on both sides in connection with heating foils arranged on heating plates, the drying temperature is quickly reached after switching on the printing device. Furthermore, the heating capacity can be regulated simply and safely due to the relatively low heat capacity of the heating plates.

In an advantageous embodiment of the invention, the heating foil can be designed in such a way that it is designed as a continuous heating foil for both heating surfaces and as a result the effort is considerably reduced.

The heat generated is used effectively for drying without significant losses. Harmful heating of the printing device can thereby be prevented.

The heat shaft can also serve as an additional paper guide and is suitable for a wide variety of paper widths.

A smudge-free guidance of recording media in printing devices, in particular in ink printing devices working with non-penetrating ink, is advantageously achieved by a plurality of toothed wheels. Since the toothed wheels have sharp-edged teeth, transfer printing onto the "freshly" printed recording medium, which is extremely wavy due to the water content of the ink, can be limited to the minimum, barely visible.

The fact that the toothed wheels are arranged on an ink drying aid provided for drying the ink results in an inexpensive fastening of the toothed wheels without having to resort to additional fastening elements. The Order of the toothed wheels on the ink drying aid also ensures that the toothed wheels are precisely assigned in the critical outlet area of the printing device. With the toothed wheels arranged on the ink drying aid, the recording medium can be guided through bottlenecks without blurring printed images, for example a heat shaft with heating elements or outlet opening with tear-off edge.

By using a molded part that is easy to produce by injection molding, preferably made of plastic, as the toothed wheel holder, the toothed wheels can be easily mounted on the ink drying aid with a small installation space.

Since the molded part also has a latching device for attachment to the ink drying aid, the molded parts with the toothed wheels can be used universally. The latching device also enables a fully automated assembly of the toothed wheel holder to be attached to the ink drying aid.

In addition, the toothed wheels can be assembled fully automatically with the molded parts to form a unit. As a result, a large number of molded parts to be mounted on the drying aid can be achieved. Thanks to the self-clawing internal toothing of the toothed wheels, the toothed wheels can be installed in a functionally reliable manner by pressing them onto a plastic bearing bush. The bearing bush can in turn be fastened by a bearing pin that can be pressed fully automatically into the molded part. By means of a collar arranged on the bearing bush with a recess excavated at the base point, the plastic shavings produced when the toothed wheel is pressed onto the bearing bush can be caught and a flush contact of the toothed wheel with the collar can be achieved.

An embodiment of the invention is explained with reference to the drawings. Show it: FIG. 1 shows a front view of a continuous paper of different widths transported by an ink drying aid according to an arrow direction I in FIG. 5,

FIG. 2 shows a side view of a guide element fastened to the ink drying aid,

3 shows a section through the guide element along a section line III ... III in FIG. 2,

FIG. 4 shows a section through the guide element along a section line IV ... IV in FIG. 3,

5 shows a sectional view of a partial section of the ink drying aid fastened to the guide element in an inkjet printing device, FIG.

FIG. 6 shows a side view of a partial section of the ink drying aid fastened with the firmly integrated guide element in the inkjet printing device.

FIG. 1 shows a front view of an ink drying aid 1 of the type used, for example, in inkjet printing devices. The ink drying aid 1 preferably has a plastic housing 10 with a heat shaft 100, in which heating elements (not shown) are arranged. Instead of plastic, however, other heat-insulating materials are also possible for the production of the housing 10 of the ink drying aid 1. Through the heat shaft 100 of the ink drying aid 1, an endless paper 3, which is transported by a platen roller 2 and has a fold 30, is pushed with a paper edge 31, an edge perforation 32 and a perforation 33 (edge-perforated folded paper) for the direction of the arrow shown. In addition to the perforated continuous paper 3, other recording media, such as, for. B. single sheets of paper, film or cardboard and film webs are pushed through the ink drying aid 1. However, the prerequisite for this is that the mentioned recording media do not exceed a predetermined maximum width.

A maximum paper width bmax must not be exceeded for the continuous perforated continuous paper 3 pushed through in the ink drying aid 1 according to FIG. 1. So that the perforated continuous paper 3 during the feed through the heat shaft 100 of the ink drying aid 1 with the "freshly" printed side does not have the heating elements arranged in the heat shaft 100 and during further feed in an exit area of the continuous paper 3 from the inkjet printing device 1 not an ab¬ Touched tear edge, several guide elements 4 are arranged on the side of the ink drying aid 1 facing the "fresh" printed image of the continuous paper 3 in the exit region of the continuous paper 3 from the heat shaft 100. The number of the guide elements 4 arranged on the ink drying aid 1 is determined according to the maximum paper widths bmax of the perforated continuous paper 3 with which the ink drying aid 1 is designed. In the present exemplary embodiment with eight guide elements 4 arranged on the ink drying aid 1, for example edge-punched continuous paper 3 in A3 or A4 landscape format with a length of 297 mm can be processed. The guide elements 4 are arranged on the housing 10 of the ink drying aid 1 on a plastic strip 11. For this purpose, the plastic strip 11 and the housing 10 have several cutouts 12 corresponding to the number of guide elements 4. The cutouts 12 are arranged on the ink drying aid 1 at an edge distance RA and a pitch TA such that the edge-perforated continuous paper 3 with the paper edge 31, the edge perforation 32 and the perforation 33 lies outside a contact area KB of the guide elements 4 is arranged with the perforated continuous paper 3.

In addition, the arrangement of the guide elements 4 on the ink drying aid 1 is selected such that even edge-perforated endospo paper 3 with a standard paper width bl with the paper edge 31, the edge perforation 32 and the perforation 33 outside of the contact area KB of the guide elements 4 with the edge-perforated continuous paper 3. The standard paper width bl of the perforated continuous paper 3 corresponds to a length of 250 mm according to the Euro standard or a length of 240 mm according to the US standard. Less a double-sided strip between the paper edge 31 and the perforation 33 of 2x20 mm (Euro standard) or 2x15 mm (US standard) results in a net width of 210 mm available for printing. This width corresponds to that of a single sheet in A4 format. In the event that edge-punched continuous paper 3 is used, the paper width of which is larger than that of the standard paper width b1 and, for example, smaller than the maximum paper width bmax, the guide elements 4 can also be spaced apart from one another on the ink drying aid 1 to be ordered. It would then be avoided again that the respective paper edge 30, edge perforation 31 and perforation 32 lie in the contact area KB of the guide elements 4 with the edge-perforated continuous paper 3.

FIG. 2 shows a side view of the guide element 4. A toothed wheel 40, which is rotatably mounted in a molded part 41 between two cheeks 410 of the molded part 41, is characteristic of the construction of the guide element 4. The toothed wheel 40 preferably consists of thin spring plate and has sharp-edged, obtuse-angled teeth 400 for forming the contact area KB. The prongs 400 are therefore preferably obtuse-angled in order to a) prevent the paper from jamming when the edge-perforated continuous paper 3 comes into contact with the toothed wheel 40, b) when the edge-perforated continuous paper 3 is fed through the heat shaft 100 the tines 400 remain in the fold 30, and for other endless papers whose paper edge, edge perforation, perforation is not matched to the predetermined pitch TA of the toothed wheels 40, in the edge perforation 32 and perforation 33 and c) according to FIG 5 and 6 when the edge-punched continuous paper 3 is torn off at a tear-off edge of the ink jet printing device, an imprint of the prongs 400 on the edge-perforated continuous paper 3 avoid. The sharp-edged teeth 401 furthermore produce an excellent grip between the toothed wheel 40 and the continuous paper 3, by means of which the toothed wheel 40 is rotated with the slightest contact with the continuous paper 3 and thus a visible transfer printing or blurring of a printed image is avoided.

The cheeks 410 of the molded part 41 are designed such that the toothed wheel 40 with a toothed wheel segment 401 protrudes from the molded part 41. As a result, the continuous paper 3 is brought specifically to the toothed wheel 40 and it is prevented that a paper jam occurs at the toothed wheel 40. In addition, the cheeks 410 represent a protective function against the sharp-edged toothed wheel 40, for example against the risk of injury. To fasten the guide element 4 to the ink drying aid 1 according to FIG. 1, the molded part 41 has a latching device 411. The latching device 411 consists of two, differently long, elastic latching legs 413, 414 which are separated from one another by a cutout 412 and which are bent at right angles to the cheeks 410 of the molded part 41. The longer latching leg 414 has a latching nose which is bent to the shorter latching leg 413 415 on. A groove 416 is provided on the inside of the molded part 41 at the connection point between the locking device 411 and the cheeks 410. The guide element 4 is suspended on the housing 10 of the ink drying aid 1 and the plastic strip 11 between the cutouts 12 via the cutout 412 and the groove 416. How the guide element 4 is attached in detail to the ink drying aid 1 is explained in the description of FIG. 5.

Figure 3 shows a section through the guide element 4 according to Figure 2 along a section line III ... III. The toothed wheel 40 is then arranged on a bearing bush 42 against a radial projection 420 coming to the system 421. On the side where the toothed wheel 40 is pushed onto the bearing bush 42 up to the radial projection 420, the bearing bush 42 is formed in steps by a step 422 to the radial projection 420, with an increasing outer radius of the bearing bush 42. The The task of paragraph 422 is that, in the case of automated assembly, the toothed wheel 40 is first pre-centered at an angle to the axis of rotation of the toothed wheel 40 and then pressed on as far as the radial projection 420. To fix the toothed wheel 40 on the bearing bush 42, the toothed wheel 40 has an internal toothing 402 which, after the toothing wheel 40 has been pre-centered, grips into the bearing bush 42 when it is pressed onto the bearing bush 42. So that the teeth of the internal toothing 402 securely claw into the bearing bush 42, the bearing bush 42, like the molded part 41, is preferably made of plastic.

The chips produced when the toothed wheel 40 is pressed onto the bearing bush 42 are received by a trough 423 arranged at the base of the radial projection 420. This ensures a secure contact of the toothed wheel 40 with the radial projection 420. A bearing pin 43 is provided for mounting the toothed wheel 40 between the cheeks 410, onto which the bearing bush 42 is pushed with a slight play between the cheeks 410 of the molded part 41. In order to make it easier to push the bearing bush 42 onto the bearing pin 43, mounting chamfers 424 are arranged on the inside of the bearing bush 42 on both end faces. In addition, the assembly chamfer 424 has the functionally important task that the toothed wheel 40 arranged on the bearing bush 42 rotates smoothly with the slightest contact with the continuous paper 3, in order to avoid visible transfer printing or blurring of the printed image. For easy rotation of the toothed wheel 40 or the bearing bush 42, however, it is equally important to have good frictional relationships between the bearing bush 42 and the bearing pin 43. Since the bearing bush 42 is preferably made of plastic, it is therefore expedient to design the bearing pin 43 to be metallic. However, it is also possible to manufacture the bearing bush 42 and the bearing pin 43 from other materials with similarly good friction conditions during storage. The ends of the bearing pin 43 can also be inserted into passage openings 417 of the cheeks 410. Forms for the axial fixing of the bearing pin 43 one of the passage openings 417 with the bearing pin 43 an interference fit.

Figure 4 shows a section through the guide element 4 of Figure 3 along a section line IV ... IV. The locking device 411 of the molded part 41 is produced as a solid plastic part, on which the cheeks 410 are molded from plastic. FIG. 4 also shows that the groove 416 is formed in the cheeks 410, at the connection point between the latching device 411 and the cheeks 410.

FIG. 5 shows a partial section of the ink drying aid 1 fastened with the guide element 4 in a paper outlet area AB of an inkjet printing device 8. The paper outlet area AB comprises the path of the continuous paper 3 between a printing station 5 and an exit area ATB of the continuous paper 3 at a tear-off edge 70 of an additional device 7, which is detachably arranged on the inkjet printing device 8. In a first embodiment, the guide element 4 is detachably fastened to the housing 10 of the ink drying aid 1 according to FIGS. The symmetrically constructed ink drying aid 1 is fastened above the printing station 5 to a holder 6 of the inkjet printing device 8 in such a way that the edge-punched continuous paper 3 advanced for the indicated direction of rotation of the platen roller 2 after the printing process at the printing station 5 into the heat shaft 100 of the ink drying aid 1 is guided. To attach the ink drying aid 1 to the holder 6 and to receive the guide element 4, the plastic strip 11 is T-shaped and is arranged symmetrically orthogonally to the heat shaft 100 on two opposite sides of the housing 10. The plastic strip 11 provided for receiving the guide element 4 has the cutouts 12 on the side facing away from the outlet opening 101 of the heat shaft 100, in the area of which the catch 415 engages behind the plastic strip 11. As a result, as shown in FIG. 5, this is done via the groove 416 on the housing 10 of the ink drying aid and via the locking legs 413, 414 locked on the plastic strip 11 guide element 4 locked. In the heat shaft 100, the edge-perforated endospo paper 3 is passed between two electrically heatable heating elements 13 located opposite each other in the heat shaft 100. The heating element 13 consists of a U-shaped heating plate 130 arranged on the inside of the housing 10 of the ink drying aid 1 and a heating foil 131 attached to the inside of the heating plate 130. Like the drying process and the drying aid 1 in detail is functioning or constructed, is described in the European patent application 89118830.2.

The continuous perforated continuous paper 3 pushed through the heat shaft 100 between the heating elements 13 meets at an outlet opening 101 of the heat shaft 100 with the toothed wheel segment 401 of the guide element 4 which projects into the outlet opening 101 and is uncovered by the cheeks 410. In the event that Edge-punched continuous paper 3 does not run directly tangentially past the toothed wheel 40 of the guide element 4, but rather sticks in the paper path with the top edge of the paper between the teeth 400, the teeth 400 have to be obtuse-angled and the toothed wheel 40 must be able to be rotated smoothly in order to avoid a paper jam due to the continuous paper getting stuck 3 in the peaks 400 to avoid. An incoming paper jam on the guide element 4 would result in the blurring of printed images due to contact with the heating element 13 if the ink on the continuous paper 3 is not yet completely dried. So that the perforated continuous paper 3 can be pushed through the heat shaft 100 without contact for optimum drying conditions, the toothed wheel 40 of the guide element 4 extends into the exit opening 101 up to the center. The contact-free pushing of the edge-punched continuous paper 3 is given for a paper running direction, in which the edge-punched continuous paper 3 with the "freshly" printed side is guided out of the ink jet printing device 8 both visually and invisibly. In addition, the non-contact pushing-through is ensured even when the edge-perforated continuous paper 3 is separated at the tear-off edge 70 of the ink jet printing device 8. As a result of the tensile stress arising when the continuous paper 3 is torn off, the endless paper 3 is pressed against the toothed wheel 40 of the guide element 4. If the teeth 400 of the toothed wheel 40 were formed too acute, they would press into the edge-perforated continuous paper 3 and leave an undesired impression.

FIG. 5 also shows various paper runs PLl... PL3 of the continuous paper 3. The paper run PLl is decisive when the continuous paper 3 is led out of the ink jet printing device 8 to the rear. The paper path PL2 is decisive for leading outward from the inkjet printing device 8. The paper path PL3 describes the course of the continuous paper 3 when tearing off at the tear-off edge 70. In addition, a paper path PL4 for a single-sheet paper 9 is shown, which is decisive when the single-sheet paper 9 is placed in a for the additional device 7 on the inkjet printing device 8 arranged storage device according to the international application PCT / DE 88/00554.

FIG. 6, based on FIG. 5, shows in a second embodiment how a guide element 4a is integrated in a stationary manner in a housing 10a of an ink drying aid 1a. The structure and arrangement of the ink drying aid 1a in the inkjet printing device 8 is identical to the ink drying aid 1 according to FIG. 5. The difference between the guide element 4a and the guide element 4 is that cheeks 410a are now provided, in which one side open slot 417a tapering toward the closed end. To support the toothed wheels 40 arranged on the bearing bushes 42, a bearing wire 43a is provided, which is inserted into the slots 417a of the cheeks 410a formed on the ink drying aid la. Because of the larger number of toothed wheels 40, for example eight, which are arranged on the ink drying aid 1 a, the bearing wire 43 a is clamped axially.

Claims

1. Device for drying and guiding printed recording media in inkjet printing devices with the following features: a) an ink drying aid (1, la) with a heatable heat shaft (100) that extends over the width of the printed recording medium (3) is for receiving the printed recording medium (3) in such a way that an approximately homogeneous temperature distribution occurs when heating in the heat shaft (100), b) the ink drying aid (1, la) is in an outlet area (AB) of the printing device (8) between a Printing station (5) and an exit area (ATB) of the printed record carrier (3) from the inkjet printing device (8) are arranged, c) the ink drying aid (1, la) are assigned guide elements (4, 4a) which are designed in this way. are that a blurring of the printed image is prevented.

2. Apparatus according to claim 1, d a d u r c h g e k e n n ¬ z e i c h n e t that the heat shaft (100) has opposite electrically heated heating elements (13) between which the recording medium (3) is passed.

3. Apparatus according to claim 1 or 2, d a d u r c h g e ¬ k e n n z e i c h n e t that the guide elements (4, 4a) are designed as rotatable toothed wheels (40).

4. Apparatus according to claim 3, d a d u r c h g e k e n n ¬ z e i c h n e t that the toothed wheels (40) made of thin Feder¬ sheet with sharp-edged, obtuse-angled pronounced teeth (400).

5. Apparatus according to claim 3 or 4, dadurchge ¬ indicates that the toothed wheel (40) has a self-locking internal toothing (402).

6. The device according to claim 5, characterized in that for the mounting of the toothed wheel (40), a bearing bush (42) with a shoulder (422) is provided, via which the toothed wheel (40) with the self-locking internal toothing ( 422) is pushed up to a collar (420) and fastened and that the collar (420) has a trough (423) on the side facing the toothed wheel (40) at the base point.

7. Device according to one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that the guide elements (4,

4a) are arranged on an outlet opening (101) of the heat shaft (100).

8. Device according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t that the guide elements (4,

4a) are covered except for a toothed wheel segment (401).

9. Device according to one of claims 1 to 8, so that the guide element (4) can be latched on the ink drying aid (1) via a latching device (411).

10. The device according to one of claims 1 to 8, that the guide element (4a) is firmly integrated in the ink drying aid (la).